xref: /sqlite-3.40.0/src/sqlite.h.in (revision b39187ae)
1/*
2** 2001 September 15
3**
4** The author disclaims copyright to this source code.  In place of
5** a legal notice, here is a blessing:
6**
7**    May you do good and not evil.
8**    May you find forgiveness for yourself and forgive others.
9**    May you share freely, never taking more than you give.
10**
11*************************************************************************
12** This header file defines the interface that the SQLite library
13** presents to client programs.  If a C-function, structure, datatype,
14** or constant definition does not appear in this file, then it is
15** not a published API of SQLite, is subject to change without
16** notice, and should not be referenced by programs that use SQLite.
17**
18** Some of the definitions that are in this file are marked as
19** "experimental".  Experimental interfaces are normally new
20** features recently added to SQLite.  We do not anticipate changes
21** to experimental interfaces but reserve to make minor changes if
22** experience from use "in the wild" suggest such changes are prudent.
23**
24** The official C-language API documentation for SQLite is derived
25** from comments in this file.  This file is the authoritative source
26** on how SQLite interfaces are suppose to operate.
27**
28** The name of this file under configuration management is "sqlite.h.in".
29** The makefile makes some minor changes to this file (such as inserting
30** the version number) and changes its name to "sqlite3.h" as
31** part of the build process.
32**
33** @(#) $Id: sqlite.h.in,v 1.421 2008/12/30 06:24:58 danielk1977 Exp $
34*/
35#ifndef _SQLITE3_H_
36#define _SQLITE3_H_
37#include <stdarg.h>     /* Needed for the definition of va_list */
38
39/*
40** Make sure we can call this stuff from C++.
41*/
42#ifdef __cplusplus
43extern "C" {
44#endif
45
46
47/*
48** Add the ability to override 'extern'
49*/
50#ifndef SQLITE_EXTERN
51# define SQLITE_EXTERN extern
52#endif
53
54/*
55** These no-op macros are used in front of interfaces to mark those
56** interfaces as either deprecated or experimental.  New applications
57** should not use deprecated intrfaces - they are support for backwards
58** compatibility only.  Application writers should be aware that
59** experimental interfaces are subject to change in point releases.
60**
61** These macros used to resolve to various kinds of compiler magic that
62** would generate warning messages when they were used.  But that
63** compiler magic ended up generating such a flurry of bug reports
64** that we have taken it all out and gone back to using simple
65** noop macros.
66*/
67#define SQLITE_DEPRECATED
68#define SQLITE_EXPERIMENTAL
69
70/*
71** Ensure these symbols were not defined by some previous header file.
72*/
73#ifdef SQLITE_VERSION
74# undef SQLITE_VERSION
75#endif
76#ifdef SQLITE_VERSION_NUMBER
77# undef SQLITE_VERSION_NUMBER
78#endif
79
80/*
81** CAPI3REF: Compile-Time Library Version Numbers {H10010} <S60100>
82**
83** The SQLITE_VERSION and SQLITE_VERSION_NUMBER #defines in
84** the sqlite3.h file specify the version of SQLite with which
85** that header file is associated.
86**
87** The "version" of SQLite is a string of the form "X.Y.Z".
88** The phrase "alpha" or "beta" might be appended after the Z.
89** The X value is major version number always 3 in SQLite3.
90** The X value only changes when backwards compatibility is
91** broken and we intend to never break backwards compatibility.
92** The Y value is the minor version number and only changes when
93** there are major feature enhancements that are forwards compatible
94** but not backwards compatible.
95** The Z value is the release number and is incremented with
96** each release but resets back to 0 whenever Y is incremented.
97**
98** See also: [sqlite3_libversion()] and [sqlite3_libversion_number()].
99**
100** INVARIANTS:
101**
102** {H10011} The SQLITE_VERSION #define in the sqlite3.h header file shall
103**          evaluate to a string literal that is the SQLite version
104**          with which the header file is associated.
105**
106** {H10014} The SQLITE_VERSION_NUMBER #define shall resolve to an integer
107**          with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z
108**          are the major version, minor version, and release number.
109*/
110#define SQLITE_VERSION         "--VERS--"
111#define SQLITE_VERSION_NUMBER  --VERSION-NUMBER--
112
113/*
114** CAPI3REF: Run-Time Library Version Numbers {H10020} <S60100>
115** KEYWORDS: sqlite3_version
116**
117** These features provide the same information as the [SQLITE_VERSION]
118** and [SQLITE_VERSION_NUMBER] #defines in the header, but are associated
119** with the library instead of the header file.  Cautious programmers might
120** include a check in their application to verify that
121** sqlite3_libversion_number() always returns the value
122** [SQLITE_VERSION_NUMBER].
123**
124** The sqlite3_libversion() function returns the same information as is
125** in the sqlite3_version[] string constant.  The function is provided
126** for use in DLLs since DLL users usually do not have direct access to string
127** constants within the DLL.
128**
129** INVARIANTS:
130**
131** {H10021} The [sqlite3_libversion_number()] interface shall return
132**          an integer equal to [SQLITE_VERSION_NUMBER].
133**
134** {H10022} The [sqlite3_version] string constant shall contain
135**          the text of the [SQLITE_VERSION] string.
136**
137** {H10023} The [sqlite3_libversion()] function shall return
138**          a pointer to the [sqlite3_version] string constant.
139*/
140SQLITE_EXTERN const char sqlite3_version[];
141const char *sqlite3_libversion(void);
142int sqlite3_libversion_number(void);
143
144/*
145** CAPI3REF: Test To See If The Library Is Threadsafe {H10100} <S60100>
146**
147** SQLite can be compiled with or without mutexes.  When
148** the [SQLITE_THREADSAFE] C preprocessor macro 1 or 2, mutexes
149** are enabled and SQLite is threadsafe.  When the
150** [SQLITE_THREADSAFE] macro is 0,
151** the mutexes are omitted.  Without the mutexes, it is not safe
152** to use SQLite concurrently from more than one thread.
153**
154** Enabling mutexes incurs a measurable performance penalty.
155** So if speed is of utmost importance, it makes sense to disable
156** the mutexes.  But for maximum safety, mutexes should be enabled.
157** The default behavior is for mutexes to be enabled.
158**
159** This interface can be used by a program to make sure that the
160** version of SQLite that it is linking against was compiled with
161** the desired setting of the [SQLITE_THREADSAFE] macro.
162**
163** This interface only reports on the compile-time mutex setting
164** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
165** SQLITE_THREADSAFE=1 then mutexes are enabled by default but
166** can be fully or partially disabled using a call to [sqlite3_config()]
167** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
168** or [SQLITE_CONFIG_MUTEX].  The return value of this function shows
169** only the default compile-time setting, not any run-time changes
170** to that setting.
171**
172** See the [threading mode] documentation for additional information.
173**
174** INVARIANTS:
175**
176** {H10101} The [sqlite3_threadsafe()] function shall return zero if
177**          and only if SQLite was compiled with mutexing code omitted.
178**
179** {H10102} The value returned by the [sqlite3_threadsafe()] function
180**          shall remain the same across calls to [sqlite3_config()].
181*/
182int sqlite3_threadsafe(void);
183
184/*
185** CAPI3REF: Database Connection Handle {H12000} <S40200>
186** KEYWORDS: {database connection} {database connections}
187**
188** Each open SQLite database is represented by a pointer to an instance of
189** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
190** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
191** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
192** is its destructor.  There are many other interfaces (such as
193** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
194** [sqlite3_busy_timeout()] to name but three) that are methods on an
195** sqlite3 object.
196*/
197typedef struct sqlite3 sqlite3;
198
199/*
200** CAPI3REF: 64-Bit Integer Types {H10200} <S10110>
201** KEYWORDS: sqlite_int64 sqlite_uint64
202**
203** Because there is no cross-platform way to specify 64-bit integer types
204** SQLite includes typedefs for 64-bit signed and unsigned integers.
205**
206** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
207** The sqlite_int64 and sqlite_uint64 types are supported for backwards
208** compatibility only.
209**
210** INVARIANTS:
211**
212** {H10201} The [sqlite_int64] and [sqlite3_int64] type shall specify
213**          a 64-bit signed integer.
214**
215** {H10202} The [sqlite_uint64] and [sqlite3_uint64] type shall specify
216**          a 64-bit unsigned integer.
217*/
218#ifdef SQLITE_INT64_TYPE
219  typedef SQLITE_INT64_TYPE sqlite_int64;
220  typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
221#elif defined(_MSC_VER) || defined(__BORLANDC__)
222  typedef __int64 sqlite_int64;
223  typedef unsigned __int64 sqlite_uint64;
224#else
225  typedef long long int sqlite_int64;
226  typedef unsigned long long int sqlite_uint64;
227#endif
228typedef sqlite_int64 sqlite3_int64;
229typedef sqlite_uint64 sqlite3_uint64;
230
231/*
232** If compiling for a processor that lacks floating point support,
233** substitute integer for floating-point.
234*/
235#ifdef SQLITE_OMIT_FLOATING_POINT
236# define double sqlite3_int64
237#endif
238
239/*
240** CAPI3REF: Closing A Database Connection {H12010} <S30100><S40200>
241**
242** This routine is the destructor for the [sqlite3] object.
243**
244** Applications should [sqlite3_finalize | finalize] all [prepared statements]
245** and [sqlite3_blob_close | close] all [BLOB handles] associated with
246** the [sqlite3] object prior to attempting to close the object.
247** The [sqlite3_next_stmt()] interface can be used to locate all
248** [prepared statements] associated with a [database connection] if desired.
249** Typical code might look like this:
250**
251** <blockquote><pre>
252** sqlite3_stmt *pStmt;
253** while( (pStmt = sqlite3_next_stmt(db, 0))!=0 ){
254** &nbsp;   sqlite3_finalize(pStmt);
255** }
256** </pre></blockquote>
257**
258** If [sqlite3_close()] is invoked while a transaction is open,
259** the transaction is automatically rolled back.
260**
261** INVARIANTS:
262**
263** {H12011} A successful call to [sqlite3_close(C)] shall destroy the
264**          [database connection] object C.
265**
266** {H12012} A successful call to [sqlite3_close(C)] shall return SQLITE_OK.
267**
268** {H12013} A successful call to [sqlite3_close(C)] shall release all
269**          memory and system resources associated with [database connection]
270**          C.
271**
272** {H12014} A call to [sqlite3_close(C)] on a [database connection] C that
273**          has one or more open [prepared statements] shall fail with
274**          an [SQLITE_BUSY] error code.
275**
276** {H12015} A call to [sqlite3_close(C)] where C is a NULL pointer shall
277**          be a harmless no-op returning SQLITE_OK.
278**
279** {H12019} When [sqlite3_close(C)] is invoked on a [database connection] C
280**          that has a pending transaction, the transaction shall be
281**          rolled back.
282**
283** ASSUMPTIONS:
284**
285** {A12016} The C parameter to [sqlite3_close(C)] must be either a NULL
286**          pointer or an [sqlite3] object pointer obtained
287**          from [sqlite3_open()], [sqlite3_open16()], or
288**          [sqlite3_open_v2()], and not previously closed.
289*/
290int sqlite3_close(sqlite3 *);
291
292/*
293** The type for a callback function.
294** This is legacy and deprecated.  It is included for historical
295** compatibility and is not documented.
296*/
297typedef int (*sqlite3_callback)(void*,int,char**, char**);
298
299/*
300** CAPI3REF: One-Step Query Execution Interface {H12100} <S10000>
301**
302** The sqlite3_exec() interface is a convenient way of running one or more
303** SQL statements without having to write a lot of C code.  The UTF-8 encoded
304** SQL statements are passed in as the second parameter to sqlite3_exec().
305** The statements are evaluated one by one until either an error or
306** an interrupt is encountered, or until they are all done.  The 3rd parameter
307** is an optional callback that is invoked once for each row of any query
308** results produced by the SQL statements.  The 5th parameter tells where
309** to write any error messages.
310**
311** The error message passed back through the 5th parameter is held
312** in memory obtained from [sqlite3_malloc()].  To avoid a memory leak,
313** the calling application should call [sqlite3_free()] on any error
314** message returned through the 5th parameter when it has finished using
315** the error message.
316**
317** If the SQL statement in the 2nd parameter is NULL or an empty string
318** or a string containing only whitespace and comments, then no SQL
319** statements are evaluated and the database is not changed.
320**
321** The sqlite3_exec() interface is implemented in terms of
322** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()].
323** The sqlite3_exec() routine does nothing to the database that cannot be done
324** by [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()].
325**
326** INVARIANTS:
327**
328** {H12101} A successful invocation of [sqlite3_exec(D,S,C,A,E)]
329**          shall sequentially evaluate all of the UTF-8 encoded,
330**          semicolon-separated SQL statements in the zero-terminated
331**          string S within the context of the [database connection] D.
332**
333** {H12102} If the S parameter to [sqlite3_exec(D,S,C,A,E)] is NULL then
334**          the actions of the interface shall be the same as if the
335**          S parameter were an empty string.
336**
337** {H12104} The return value of [sqlite3_exec()] shall be [SQLITE_OK] if all
338**          SQL statements run successfully and to completion.
339**
340** {H12105} The return value of [sqlite3_exec()] shall be an appropriate
341**          non-zero [error code] if any SQL statement fails.
342**
343** {H12107} If one or more of the SQL statements handed to [sqlite3_exec()]
344**          return results and the 3rd parameter is not NULL, then
345**          the callback function specified by the 3rd parameter shall be
346**          invoked once for each row of result.
347**
348** {H12110} If the callback returns a non-zero value then [sqlite3_exec()]
349**          shall abort the SQL statement it is currently evaluating,
350**          skip all subsequent SQL statements, and return [SQLITE_ABORT].
351**
352** {H12113} The [sqlite3_exec()] routine shall pass its 4th parameter through
353**          as the 1st parameter of the callback.
354**
355** {H12116} The [sqlite3_exec()] routine shall set the 2nd parameter of its
356**          callback to be the number of columns in the current row of
357**          result.
358**
359** {H12119} The [sqlite3_exec()] routine shall set the 3rd parameter of its
360**          callback to be an array of pointers to strings holding the
361**          values for each column in the current result set row as
362**          obtained from [sqlite3_column_text()].
363**
364** {H12122} The [sqlite3_exec()] routine shall set the 4th parameter of its
365**          callback to be an array of pointers to strings holding the
366**          names of result columns as obtained from [sqlite3_column_name()].
367**
368** {H12125} If the 3rd parameter to [sqlite3_exec()] is NULL then
369**          [sqlite3_exec()] shall silently discard query results.
370**
371** {H12131} If an error occurs while parsing or evaluating any of the SQL
372**          statements in the S parameter of [sqlite3_exec(D,S,C,A,E)] and if
373**          the E parameter is not NULL, then [sqlite3_exec()] shall store
374**          in *E an appropriate error message written into memory obtained
375**          from [sqlite3_malloc()].
376**
377** {H12134} The [sqlite3_exec(D,S,C,A,E)] routine shall set the value of
378**          *E to NULL if E is not NULL and there are no errors.
379**
380** {H12137} The [sqlite3_exec(D,S,C,A,E)] function shall set the [error code]
381**          and message accessible via [sqlite3_errcode()],
382**          [sqlite3_extended_errcode()],
383**          [sqlite3_errmsg()], and [sqlite3_errmsg16()].
384**
385** {H12138} If the S parameter to [sqlite3_exec(D,S,C,A,E)] is NULL or an
386**          empty string or contains nothing other than whitespace, comments,
387**          and/or semicolons, then results of [sqlite3_errcode()],
388**          [sqlite3_extended_errcode()],
389**          [sqlite3_errmsg()], and [sqlite3_errmsg16()]
390**          shall reset to indicate no errors.
391**
392** ASSUMPTIONS:
393**
394** {A12141} The first parameter to [sqlite3_exec()] must be an valid and open
395**          [database connection].
396**
397** {A12142} The database connection must not be closed while
398**          [sqlite3_exec()] is running.
399**
400** {A12143} The calling function should use [sqlite3_free()] to free
401**          the memory that *errmsg is left pointing at once the error
402**          message is no longer needed.
403**
404** {A12145} The SQL statement text in the 2nd parameter to [sqlite3_exec()]
405**          must remain unchanged while [sqlite3_exec()] is running.
406*/
407int sqlite3_exec(
408  sqlite3*,                                  /* An open database */
409  const char *sql,                           /* SQL to be evaluated */
410  int (*callback)(void*,int,char**,char**),  /* Callback function */
411  void *,                                    /* 1st argument to callback */
412  char **errmsg                              /* Error msg written here */
413);
414
415/*
416** CAPI3REF: Result Codes {H10210} <S10700>
417** KEYWORDS: SQLITE_OK {error code} {error codes}
418** KEYWORDS: {result code} {result codes}
419**
420** Many SQLite functions return an integer result code from the set shown
421** here in order to indicates success or failure.
422**
423** New error codes may be added in future versions of SQLite.
424**
425** See also: [SQLITE_IOERR_READ | extended result codes]
426*/
427#define SQLITE_OK           0   /* Successful result */
428/* beginning-of-error-codes */
429#define SQLITE_ERROR        1   /* SQL error or missing database */
430#define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
431#define SQLITE_PERM         3   /* Access permission denied */
432#define SQLITE_ABORT        4   /* Callback routine requested an abort */
433#define SQLITE_BUSY         5   /* The database file is locked */
434#define SQLITE_LOCKED       6   /* A table in the database is locked */
435#define SQLITE_NOMEM        7   /* A malloc() failed */
436#define SQLITE_READONLY     8   /* Attempt to write a readonly database */
437#define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
438#define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
439#define SQLITE_CORRUPT     11   /* The database disk image is malformed */
440#define SQLITE_NOTFOUND    12   /* NOT USED. Table or record not found */
441#define SQLITE_FULL        13   /* Insertion failed because database is full */
442#define SQLITE_CANTOPEN    14   /* Unable to open the database file */
443#define SQLITE_PROTOCOL    15   /* NOT USED. Database lock protocol error */
444#define SQLITE_EMPTY       16   /* Database is empty */
445#define SQLITE_SCHEMA      17   /* The database schema changed */
446#define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
447#define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
448#define SQLITE_MISMATCH    20   /* Data type mismatch */
449#define SQLITE_MISUSE      21   /* Library used incorrectly */
450#define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
451#define SQLITE_AUTH        23   /* Authorization denied */
452#define SQLITE_FORMAT      24   /* Auxiliary database format error */
453#define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
454#define SQLITE_NOTADB      26   /* File opened that is not a database file */
455#define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
456#define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
457/* end-of-error-codes */
458
459/*
460** CAPI3REF: Extended Result Codes {H10220} <S10700>
461** KEYWORDS: {extended error code} {extended error codes}
462** KEYWORDS: {extended result code} {extended result codes}
463**
464** In its default configuration, SQLite API routines return one of 26 integer
465** [SQLITE_OK | result codes].  However, experience has shown that many of
466** these result codes are too coarse-grained.  They do not provide as
467** much information about problems as programmers might like.  In an effort to
468** address this, newer versions of SQLite (version 3.3.8 and later) include
469** support for additional result codes that provide more detailed information
470** about errors. The extended result codes are enabled or disabled
471** on a per database connection basis using the
472** [sqlite3_extended_result_codes()] API.
473**
474** Some of the available extended result codes are listed here.
475** One may expect the number of extended result codes will be expand
476** over time.  Software that uses extended result codes should expect
477** to see new result codes in future releases of SQLite.
478**
479** The SQLITE_OK result code will never be extended.  It will always
480** be exactly zero.
481**
482** INVARIANTS:
483**
484** {H10223} The symbolic name for an extended result code shall contains
485**          a related primary result code as a prefix.
486**
487** {H10224} Primary result code names shall contain a single "_" character.
488**
489** {H10225} Extended result code names shall contain two or more "_" characters.
490**
491** {H10226} The numeric value of an extended result code shall contain the
492**          numeric value of its corresponding primary result code in
493**          its least significant 8 bits.
494*/
495#define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
496#define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
497#define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
498#define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
499#define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
500#define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
501#define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
502#define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
503#define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
504#define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
505#define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
506#define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
507#define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
508#define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
509#define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
510#define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
511#define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
512
513/*
514** CAPI3REF: Flags For File Open Operations {H10230} <H11120> <H12700>
515**
516** These bit values are intended for use in the
517** 3rd parameter to the [sqlite3_open_v2()] interface and
518** in the 4th parameter to the xOpen method of the
519** [sqlite3_vfs] object.
520*/
521#define SQLITE_OPEN_READONLY         0x00000001
522#define SQLITE_OPEN_READWRITE        0x00000002
523#define SQLITE_OPEN_CREATE           0x00000004
524#define SQLITE_OPEN_DELETEONCLOSE    0x00000008
525#define SQLITE_OPEN_EXCLUSIVE        0x00000010
526#define SQLITE_OPEN_MAIN_DB          0x00000100
527#define SQLITE_OPEN_TEMP_DB          0x00000200
528#define SQLITE_OPEN_TRANSIENT_DB     0x00000400
529#define SQLITE_OPEN_MAIN_JOURNAL     0x00000800
530#define SQLITE_OPEN_TEMP_JOURNAL     0x00001000
531#define SQLITE_OPEN_SUBJOURNAL       0x00002000
532#define SQLITE_OPEN_MASTER_JOURNAL   0x00004000
533#define SQLITE_OPEN_NOMUTEX          0x00008000
534#define SQLITE_OPEN_FULLMUTEX        0x00010000
535
536/*
537** CAPI3REF: Device Characteristics {H10240} <H11120>
538**
539** The xDeviceCapabilities method of the [sqlite3_io_methods]
540** object returns an integer which is a vector of the these
541** bit values expressing I/O characteristics of the mass storage
542** device that holds the file that the [sqlite3_io_methods]
543** refers to.
544**
545** The SQLITE_IOCAP_ATOMIC property means that all writes of
546** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
547** mean that writes of blocks that are nnn bytes in size and
548** are aligned to an address which is an integer multiple of
549** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
550** that when data is appended to a file, the data is appended
551** first then the size of the file is extended, never the other
552** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
553** information is written to disk in the same order as calls
554** to xWrite().
555*/
556#define SQLITE_IOCAP_ATOMIC          0x00000001
557#define SQLITE_IOCAP_ATOMIC512       0x00000002
558#define SQLITE_IOCAP_ATOMIC1K        0x00000004
559#define SQLITE_IOCAP_ATOMIC2K        0x00000008
560#define SQLITE_IOCAP_ATOMIC4K        0x00000010
561#define SQLITE_IOCAP_ATOMIC8K        0x00000020
562#define SQLITE_IOCAP_ATOMIC16K       0x00000040
563#define SQLITE_IOCAP_ATOMIC32K       0x00000080
564#define SQLITE_IOCAP_ATOMIC64K       0x00000100
565#define SQLITE_IOCAP_SAFE_APPEND     0x00000200
566#define SQLITE_IOCAP_SEQUENTIAL      0x00000400
567
568/*
569** CAPI3REF: File Locking Levels {H10250} <H11120> <H11310>
570**
571** SQLite uses one of these integer values as the second
572** argument to calls it makes to the xLock() and xUnlock() methods
573** of an [sqlite3_io_methods] object.
574*/
575#define SQLITE_LOCK_NONE          0
576#define SQLITE_LOCK_SHARED        1
577#define SQLITE_LOCK_RESERVED      2
578#define SQLITE_LOCK_PENDING       3
579#define SQLITE_LOCK_EXCLUSIVE     4
580
581/*
582** CAPI3REF: Synchronization Type Flags {H10260} <H11120>
583**
584** When SQLite invokes the xSync() method of an
585** [sqlite3_io_methods] object it uses a combination of
586** these integer values as the second argument.
587**
588** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
589** sync operation only needs to flush data to mass storage.  Inode
590** information need not be flushed. The SQLITE_SYNC_NORMAL flag means
591** to use normal fsync() semantics. The SQLITE_SYNC_FULL flag means
592** to use Mac OS X style fullsync instead of fsync().
593*/
594#define SQLITE_SYNC_NORMAL        0x00002
595#define SQLITE_SYNC_FULL          0x00003
596#define SQLITE_SYNC_DATAONLY      0x00010
597
598/*
599** CAPI3REF: OS Interface Open File Handle {H11110} <S20110>
600**
601** An [sqlite3_file] object represents an open file in the OS
602** interface layer.  Individual OS interface implementations will
603** want to subclass this object by appending additional fields
604** for their own use.  The pMethods entry is a pointer to an
605** [sqlite3_io_methods] object that defines methods for performing
606** I/O operations on the open file.
607*/
608typedef struct sqlite3_file sqlite3_file;
609struct sqlite3_file {
610  const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
611};
612
613/*
614** CAPI3REF: OS Interface File Virtual Methods Object {H11120} <S20110>
615**
616** Every file opened by the [sqlite3_vfs] xOpen method populates an
617** [sqlite3_file] object (or, more commonly, a subclass of the
618** [sqlite3_file] object) with a pointer to an instance of this object.
619** This object defines the methods used to perform various operations
620** against the open file represented by the [sqlite3_file] object.
621**
622** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
623** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
624** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
625** flag may be ORed in to indicate that only the data of the file
626** and not its inode needs to be synced.
627**
628** The integer values to xLock() and xUnlock() are one of
629** <ul>
630** <li> [SQLITE_LOCK_NONE],
631** <li> [SQLITE_LOCK_SHARED],
632** <li> [SQLITE_LOCK_RESERVED],
633** <li> [SQLITE_LOCK_PENDING], or
634** <li> [SQLITE_LOCK_EXCLUSIVE].
635** </ul>
636** xLock() increases the lock. xUnlock() decreases the lock.
637** The xCheckReservedLock() method checks whether any database connection,
638** either in this process or in some other process, is holding a RESERVED,
639** PENDING, or EXCLUSIVE lock on the file.  It returns true
640** if such a lock exists and false otherwise.
641**
642** The xFileControl() method is a generic interface that allows custom
643** VFS implementations to directly control an open file using the
644** [sqlite3_file_control()] interface.  The second "op" argument is an
645** integer opcode.  The third argument is a generic pointer intended to
646** point to a structure that may contain arguments or space in which to
647** write return values.  Potential uses for xFileControl() might be
648** functions to enable blocking locks with timeouts, to change the
649** locking strategy (for example to use dot-file locks), to inquire
650** about the status of a lock, or to break stale locks.  The SQLite
651** core reserves all opcodes less than 100 for its own use.
652** A [SQLITE_FCNTL_LOCKSTATE | list of opcodes] less than 100 is available.
653** Applications that define a custom xFileControl method should use opcodes
654** greater than 100 to avoid conflicts.
655**
656** The xSectorSize() method returns the sector size of the
657** device that underlies the file.  The sector size is the
658** minimum write that can be performed without disturbing
659** other bytes in the file.  The xDeviceCharacteristics()
660** method returns a bit vector describing behaviors of the
661** underlying device:
662**
663** <ul>
664** <li> [SQLITE_IOCAP_ATOMIC]
665** <li> [SQLITE_IOCAP_ATOMIC512]
666** <li> [SQLITE_IOCAP_ATOMIC1K]
667** <li> [SQLITE_IOCAP_ATOMIC2K]
668** <li> [SQLITE_IOCAP_ATOMIC4K]
669** <li> [SQLITE_IOCAP_ATOMIC8K]
670** <li> [SQLITE_IOCAP_ATOMIC16K]
671** <li> [SQLITE_IOCAP_ATOMIC32K]
672** <li> [SQLITE_IOCAP_ATOMIC64K]
673** <li> [SQLITE_IOCAP_SAFE_APPEND]
674** <li> [SQLITE_IOCAP_SEQUENTIAL]
675** </ul>
676**
677** The SQLITE_IOCAP_ATOMIC property means that all writes of
678** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
679** mean that writes of blocks that are nnn bytes in size and
680** are aligned to an address which is an integer multiple of
681** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
682** that when data is appended to a file, the data is appended
683** first then the size of the file is extended, never the other
684** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
685** information is written to disk in the same order as calls
686** to xWrite().
687**
688** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
689** in the unread portions of the buffer with zeros.  A VFS that
690** fails to zero-fill short reads might seem to work.  However,
691** failure to zero-fill short reads will eventually lead to
692** database corruption.
693*/
694typedef struct sqlite3_io_methods sqlite3_io_methods;
695struct sqlite3_io_methods {
696  int iVersion;
697  int (*xClose)(sqlite3_file*);
698  int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
699  int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
700  int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
701  int (*xSync)(sqlite3_file*, int flags);
702  int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
703  int (*xLock)(sqlite3_file*, int);
704  int (*xUnlock)(sqlite3_file*, int);
705  int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
706  int (*xFileControl)(sqlite3_file*, int op, void *pArg);
707  int (*xSectorSize)(sqlite3_file*);
708  int (*xDeviceCharacteristics)(sqlite3_file*);
709  /* Additional methods may be added in future releases */
710};
711
712/*
713** CAPI3REF: Standard File Control Opcodes {H11310} <S30800>
714**
715** These integer constants are opcodes for the xFileControl method
716** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
717** interface.
718**
719** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
720** opcode causes the xFileControl method to write the current state of
721** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
722** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
723** into an integer that the pArg argument points to. This capability
724** is used during testing and only needs to be supported when SQLITE_TEST
725** is defined.
726*/
727#define SQLITE_FCNTL_LOCKSTATE        1
728#define SQLITE_GET_LOCKPROXYFILE      2
729#define SQLITE_SET_LOCKPROXYFILE      3
730#define SQLITE_LAST_ERRNO             4
731
732/*
733** CAPI3REF: Mutex Handle {H17110} <S20130>
734**
735** The mutex module within SQLite defines [sqlite3_mutex] to be an
736** abstract type for a mutex object.  The SQLite core never looks
737** at the internal representation of an [sqlite3_mutex].  It only
738** deals with pointers to the [sqlite3_mutex] object.
739**
740** Mutexes are created using [sqlite3_mutex_alloc()].
741*/
742typedef struct sqlite3_mutex sqlite3_mutex;
743
744/*
745** CAPI3REF: OS Interface Object {H11140} <S20100>
746**
747** An instance of the sqlite3_vfs object defines the interface between
748** the SQLite core and the underlying operating system.  The "vfs"
749** in the name of the object stands for "virtual file system".
750**
751** The value of the iVersion field is initially 1 but may be larger in
752** future versions of SQLite.  Additional fields may be appended to this
753** object when the iVersion value is increased.  Note that the structure
754** of the sqlite3_vfs object changes in the transaction between
755** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
756** modified.
757**
758** The szOsFile field is the size of the subclassed [sqlite3_file]
759** structure used by this VFS.  mxPathname is the maximum length of
760** a pathname in this VFS.
761**
762** Registered sqlite3_vfs objects are kept on a linked list formed by
763** the pNext pointer.  The [sqlite3_vfs_register()]
764** and [sqlite3_vfs_unregister()] interfaces manage this list
765** in a thread-safe way.  The [sqlite3_vfs_find()] interface
766** searches the list.  Neither the application code nor the VFS
767** implementation should use the pNext pointer.
768**
769** The pNext field is the only field in the sqlite3_vfs
770** structure that SQLite will ever modify.  SQLite will only access
771** or modify this field while holding a particular static mutex.
772** The application should never modify anything within the sqlite3_vfs
773** object once the object has been registered.
774**
775** The zName field holds the name of the VFS module.  The name must
776** be unique across all VFS modules.
777**
778** SQLite will guarantee that the zFilename parameter to xOpen
779** is either a NULL pointer or string obtained
780** from xFullPathname().  SQLite further guarantees that
781** the string will be valid and unchanged until xClose() is
782** called. Because of the previous sentense,
783** the [sqlite3_file] can safely store a pointer to the
784** filename if it needs to remember the filename for some reason.
785** If the zFilename parameter is xOpen is a NULL pointer then xOpen
786** must invite its own temporary name for the file.  Whenever the
787** xFilename parameter is NULL it will also be the case that the
788** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
789**
790** The flags argument to xOpen() includes all bits set in
791** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
792** or [sqlite3_open16()] is used, then flags includes at least
793** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE].
794** If xOpen() opens a file read-only then it sets *pOutFlags to
795** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
796**
797** SQLite will also add one of the following flags to the xOpen()
798** call, depending on the object being opened:
799**
800** <ul>
801** <li>  [SQLITE_OPEN_MAIN_DB]
802** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
803** <li>  [SQLITE_OPEN_TEMP_DB]
804** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
805** <li>  [SQLITE_OPEN_TRANSIENT_DB]
806** <li>  [SQLITE_OPEN_SUBJOURNAL]
807** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
808** </ul>
809**
810** The file I/O implementation can use the object type flags to
811** change the way it deals with files.  For example, an application
812** that does not care about crash recovery or rollback might make
813** the open of a journal file a no-op.  Writes to this journal would
814** also be no-ops, and any attempt to read the journal would return
815** SQLITE_IOERR.  Or the implementation might recognize that a database
816** file will be doing page-aligned sector reads and writes in a random
817** order and set up its I/O subsystem accordingly.
818**
819** SQLite might also add one of the following flags to the xOpen method:
820**
821** <ul>
822** <li> [SQLITE_OPEN_DELETEONCLOSE]
823** <li> [SQLITE_OPEN_EXCLUSIVE]
824** </ul>
825**
826** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
827** deleted when it is closed.  The [SQLITE_OPEN_DELETEONCLOSE]
828** will be set for TEMP  databases, journals and for subjournals.
829**
830** The [SQLITE_OPEN_EXCLUSIVE] flag means the file should be opened
831** for exclusive access.  This flag is set for all files except
832** for the main database file.
833**
834** At least szOsFile bytes of memory are allocated by SQLite
835** to hold the  [sqlite3_file] structure passed as the third
836** argument to xOpen.  The xOpen method does not have to
837** allocate the structure; it should just fill it in.
838**
839** The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
840** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
841** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
842** to test whether a file is at least readable.   The file can be a
843** directory.
844**
845** SQLite will always allocate at least mxPathname+1 bytes for the
846** output buffer xFullPathname.  The exact size of the output buffer
847** is also passed as a parameter to both  methods. If the output buffer
848** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
849** handled as a fatal error by SQLite, vfs implementations should endeavor
850** to prevent this by setting mxPathname to a sufficiently large value.
851**
852** The xRandomness(), xSleep(), and xCurrentTime() interfaces
853** are not strictly a part of the filesystem, but they are
854** included in the VFS structure for completeness.
855** The xRandomness() function attempts to return nBytes bytes
856** of good-quality randomness into zOut.  The return value is
857** the actual number of bytes of randomness obtained.
858** The xSleep() method causes the calling thread to sleep for at
859** least the number of microseconds given.  The xCurrentTime()
860** method returns a Julian Day Number for the current date and time.
861**
862*/
863typedef struct sqlite3_vfs sqlite3_vfs;
864struct sqlite3_vfs {
865  int iVersion;            /* Structure version number */
866  int szOsFile;            /* Size of subclassed sqlite3_file */
867  int mxPathname;          /* Maximum file pathname length */
868  sqlite3_vfs *pNext;      /* Next registered VFS */
869  const char *zName;       /* Name of this virtual file system */
870  void *pAppData;          /* Pointer to application-specific data */
871  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
872               int flags, int *pOutFlags);
873  int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
874  int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
875  int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
876  void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
877  void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
878  void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
879  void (*xDlClose)(sqlite3_vfs*, void*);
880  int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
881  int (*xSleep)(sqlite3_vfs*, int microseconds);
882  int (*xCurrentTime)(sqlite3_vfs*, double*);
883  int (*xGetLastError)(sqlite3_vfs*, int, char *);
884  /* New fields may be appended in figure versions.  The iVersion
885  ** value will increment whenever this happens. */
886};
887
888/*
889** CAPI3REF: Flags for the xAccess VFS method {H11190} <H11140>
890**
891** These integer constants can be used as the third parameter to
892** the xAccess method of an [sqlite3_vfs] object. {END}  They determine
893** what kind of permissions the xAccess method is looking for.
894** With SQLITE_ACCESS_EXISTS, the xAccess method
895** simply checks whether the file exists.
896** With SQLITE_ACCESS_READWRITE, the xAccess method
897** checks whether the file is both readable and writable.
898** With SQLITE_ACCESS_READ, the xAccess method
899** checks whether the file is readable.
900*/
901#define SQLITE_ACCESS_EXISTS    0
902#define SQLITE_ACCESS_READWRITE 1
903#define SQLITE_ACCESS_READ      2
904
905/*
906** CAPI3REF: Initialize The SQLite Library {H10130} <S20000><S30100>
907**
908** The sqlite3_initialize() routine initializes the
909** SQLite library.  The sqlite3_shutdown() routine
910** deallocates any resources that were allocated by sqlite3_initialize().
911**
912** A call to sqlite3_initialize() is an "effective" call if it is
913** the first time sqlite3_initialize() is invoked during the lifetime of
914** the process, or if it is the first time sqlite3_initialize() is invoked
915** following a call to sqlite3_shutdown().  Only an effective call
916** of sqlite3_initialize() does any initialization.  All other calls
917** are harmless no-ops.
918**
919** Among other things, sqlite3_initialize() shall invoke
920** sqlite3_os_init().  Similarly, sqlite3_shutdown()
921** shall invoke sqlite3_os_end().
922**
923** The sqlite3_initialize() routine returns [SQLITE_OK] on success.
924** If for some reason, sqlite3_initialize() is unable to initialize
925** the library (perhaps it is unable to allocate a needed resource such
926** as a mutex) it returns an [error code] other than [SQLITE_OK].
927**
928** The sqlite3_initialize() routine is called internally by many other
929** SQLite interfaces so that an application usually does not need to
930** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
931** calls sqlite3_initialize() so the SQLite library will be automatically
932** initialized when [sqlite3_open()] is called if it has not be initialized
933** already.  However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
934** compile-time option, then the automatic calls to sqlite3_initialize()
935** are omitted and the application must call sqlite3_initialize() directly
936** prior to using any other SQLite interface.  For maximum portability,
937** it is recommended that applications always invoke sqlite3_initialize()
938** directly prior to using any other SQLite interface.  Future releases
939** of SQLite may require this.  In other words, the behavior exhibited
940** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
941** default behavior in some future release of SQLite.
942**
943** The sqlite3_os_init() routine does operating-system specific
944** initialization of the SQLite library.  The sqlite3_os_end()
945** routine undoes the effect of sqlite3_os_init().  Typical tasks
946** performed by these routines include allocation or deallocation
947** of static resources, initialization of global variables,
948** setting up a default [sqlite3_vfs] module, or setting up
949** a default configuration using [sqlite3_config()].
950**
951** The application should never invoke either sqlite3_os_init()
952** or sqlite3_os_end() directly.  The application should only invoke
953** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
954** interface is called automatically by sqlite3_initialize() and
955** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
956** implementations for sqlite3_os_init() and sqlite3_os_end()
957** are built into SQLite when it is compiled for unix, windows, or os/2.
958** When built for other platforms (using the [SQLITE_OS_OTHER=1] compile-time
959** option) the application must supply a suitable implementation for
960** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
961** implementation of sqlite3_os_init() or sqlite3_os_end()
962** must return [SQLITE_OK] on success and some other [error code] upon
963** failure.
964*/
965int sqlite3_initialize(void);
966int sqlite3_shutdown(void);
967int sqlite3_os_init(void);
968int sqlite3_os_end(void);
969
970/*
971** CAPI3REF: Configuring The SQLite Library {H14100} <S20000><S30200>
972** EXPERIMENTAL
973**
974** The sqlite3_config() interface is used to make global configuration
975** changes to SQLite in order to tune SQLite to the specific needs of
976** the application.  The default configuration is recommended for most
977** applications and so this routine is usually not necessary.  It is
978** provided to support rare applications with unusual needs.
979**
980** The sqlite3_config() interface is not threadsafe.  The application
981** must insure that no other SQLite interfaces are invoked by other
982** threads while sqlite3_config() is running.  Furthermore, sqlite3_config()
983** may only be invoked prior to library initialization using
984** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
985** Note, however, that sqlite3_config() can be called as part of the
986** implementation of an application-defined [sqlite3_os_init()].
987**
988** The first argument to sqlite3_config() is an integer
989** [SQLITE_CONFIG_SINGLETHREAD | configuration option] that determines
990** what property of SQLite is to be configured.  Subsequent arguments
991** vary depending on the [SQLITE_CONFIG_SINGLETHREAD | configuration option]
992** in the first argument.
993**
994** When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
995** If the option is unknown or SQLite is unable to set the option
996** then this routine returns a non-zero [error code].
997**
998** INVARIANTS:
999**
1000** {H14103} A successful invocation of [sqlite3_config()] shall return
1001**          [SQLITE_OK].
1002**
1003** {H14106} The [sqlite3_config()] interface shall return [SQLITE_MISUSE]
1004**          if it is invoked in between calls to [sqlite3_initialize()] and
1005**          [sqlite3_shutdown()].
1006**
1007** {H14120} A successful call to [sqlite3_config]([SQLITE_CONFIG_SINGLETHREAD])
1008**          shall set the default [threading mode] to Single-thread.
1009**
1010** {H14123} A successful call to [sqlite3_config]([SQLITE_CONFIG_MULTITHREAD])
1011**          shall set the default [threading mode] to Multi-thread.
1012**
1013** {H14126} A successful call to [sqlite3_config]([SQLITE_CONFIG_SERIALIZED])
1014**          shall set the default [threading mode] to Serialized.
1015**
1016** {H14129} A successful call to [sqlite3_config]([SQLITE_CONFIG_MUTEX],X)
1017**          where X is a pointer to an initialized [sqlite3_mutex_methods]
1018**          object shall cause all subsequent mutex operations performed
1019**          by SQLite to use the mutex methods that were present in X
1020**          during the call to [sqlite3_config()].
1021**
1022** {H14132} A successful call to [sqlite3_config]([SQLITE_CONFIG_GETMUTEX],X)
1023**          where X is a pointer to an [sqlite3_mutex_methods] object
1024**          shall overwrite the content of [sqlite3_mutex_methods] object
1025**          with the mutex methods currently in use by SQLite.
1026**
1027** {H14135} A successful call to [sqlite3_config]([SQLITE_CONFIG_MALLOC],M)
1028**          where M is a pointer to an initialized [sqlite3_mem_methods]
1029**          object shall cause all subsequent memory allocation operations
1030**          performed by SQLite to use the methods that were present in
1031**          M during the call to [sqlite3_config()].
1032**
1033** {H14138} A successful call to [sqlite3_config]([SQLITE_CONFIG_GETMALLOC],M)
1034**          where M is a pointer to an [sqlite3_mem_methods] object shall
1035**          overwrite the content of [sqlite3_mem_methods] object with
1036**          the memory allocation methods currently in use by
1037**          SQLite.
1038**
1039** {H14141} A successful call to [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],1)
1040**          shall enable the memory allocation status collection logic.
1041**
1042** {H14144} A successful call to [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],0)
1043**          shall disable the memory allocation status collection logic.
1044**
1045** {H14147} The memory allocation status collection logic shall be
1046**          enabled by default.
1047**
1048** {H14150} A successful call to [sqlite3_config]([SQLITE_CONFIG_SCRATCH],S,Z,N)
1049**          where Z and N are non-negative integers and
1050**          S is a pointer to an aligned memory buffer not less than
1051**          Z*N bytes in size shall cause S to be used by the
1052**          [scratch memory allocator] for as many as N simulataneous
1053**          allocations each of size (Z & ~7).
1054**
1055** {H14153} A successful call to [sqlite3_config]([SQLITE_CONFIG_SCRATCH],S,Z,N)
1056**          where S is a NULL pointer shall disable the
1057**          [scratch memory allocator].
1058**
1059** {H14156} A successful call to
1060**          [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],S,Z,N)
1061**          where Z and N are non-negative integers and
1062**          S is a pointer to an aligned memory buffer not less than
1063**          Z*N bytes in size shall cause S to be used by the
1064**          [pagecache memory allocator] for as many as N simulataneous
1065**          allocations each of size (Z & ~7).
1066**
1067** {H14159} A successful call to
1068**          [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],S,Z,N)
1069**          where S is a NULL pointer shall disable the
1070**          [pagecache memory allocator].
1071**
1072** {H14162} A successful call to [sqlite3_config]([SQLITE_CONFIG_HEAP],H,Z,N)
1073**          where Z and N are non-negative integers and
1074**          H is a pointer to an aligned memory buffer not less than
1075**          Z bytes in size shall enable the [memsys5] memory allocator
1076**          and cause it to use buffer S as its memory source and to use
1077**          a minimum allocation size of N.
1078**
1079** {H14165} A successful call to [sqlite3_config]([SQLITE_CONFIG_HEAP],H,Z,N)
1080**          where H is a NULL pointer shall disable the
1081**          [memsys5] memory allocator.
1082**
1083** {H14168} A successful call to [sqlite3_config]([SQLITE_CONFIG_LOOKASIDE],Z,N)
1084**          shall cause the default [lookaside memory allocator] configuration
1085**          for new [database connections] to be N slots of Z bytes each.
1086*/
1087SQLITE_EXPERIMENTAL int sqlite3_config(int, ...);
1088
1089/*
1090** CAPI3REF: Configure database connections  {H14200} <S20000>
1091** EXPERIMENTAL
1092**
1093** The sqlite3_db_config() interface is used to make configuration
1094** changes to a [database connection].  The interface is similar to
1095** [sqlite3_config()] except that the changes apply to a single
1096** [database connection] (specified in the first argument).  The
1097** sqlite3_db_config() interface can only be used immediately after
1098** the database connection is created using [sqlite3_open()],
1099** [sqlite3_open16()], or [sqlite3_open_v2()].
1100**
1101** The second argument to sqlite3_db_config(D,V,...)  is the
1102** configuration verb - an integer code that indicates what
1103** aspect of the [database connection] is being configured.
1104** The only choice for this value is [SQLITE_DBCONFIG_LOOKASIDE].
1105** New verbs are likely to be added in future releases of SQLite.
1106** Additional arguments depend on the verb.
1107**
1108** INVARIANTS:
1109**
1110** {H14203} A call to [sqlite3_db_config(D,V,...)] shall return [SQLITE_OK]
1111**          if and only if the call is successful.
1112**
1113** {H14206} If one or more slots of the [lookaside memory allocator] for
1114**          [database connection] D are in use, then a call to
1115**          [sqlite3_db_config](D,[SQLITE_DBCONFIG_LOOKASIDE],...) shall
1116**          fail with an [SQLITE_BUSY] return code.
1117**
1118** {H14209} A successful call to
1119**          [sqlite3_db_config](D,[SQLITE_DBCONFIG_LOOKASIDE],B,Z,N) where
1120**          D is an open [database connection] and Z and N are positive
1121**          integers and B is an aligned buffer at least Z*N bytes in size
1122**          shall cause the [lookaside memory allocator] for D to use buffer B
1123**          with N slots of Z bytes each.
1124**
1125** {H14212} A successful call to
1126**          [sqlite3_db_config](D,[SQLITE_DBCONFIG_LOOKASIDE],B,Z,N) where
1127**          D is an open [database connection] and Z and N are positive
1128**          integers and B is NULL pointer shall cause the
1129**          [lookaside memory allocator] for D to a obtain Z*N byte buffer
1130**          from the primary memory allocator and use that buffer
1131**          with N lookaside slots of Z bytes each.
1132**
1133** {H14215} A successful call to
1134**          [sqlite3_db_config](D,[SQLITE_DBCONFIG_LOOKASIDE],B,Z,N) where
1135**          D is an open [database connection] and Z and N are zero shall
1136**          disable the [lookaside memory allocator] for D.
1137**
1138**
1139*/
1140SQLITE_EXPERIMENTAL int sqlite3_db_config(sqlite3*, int op, ...);
1141
1142/*
1143** CAPI3REF: Memory Allocation Routines {H10155} <S20120>
1144** EXPERIMENTAL
1145**
1146** An instance of this object defines the interface between SQLite
1147** and low-level memory allocation routines.
1148**
1149** This object is used in only one place in the SQLite interface.
1150** A pointer to an instance of this object is the argument to
1151** [sqlite3_config()] when the configuration option is
1152** [SQLITE_CONFIG_MALLOC].  By creating an instance of this object
1153** and passing it to [sqlite3_config()] during configuration, an
1154** application can specify an alternative memory allocation subsystem
1155** for SQLite to use for all of its dynamic memory needs.
1156**
1157** Note that SQLite comes with a built-in memory allocator that is
1158** perfectly adequate for the overwhelming majority of applications
1159** and that this object is only useful to a tiny minority of applications
1160** with specialized memory allocation requirements.  This object is
1161** also used during testing of SQLite in order to specify an alternative
1162** memory allocator that simulates memory out-of-memory conditions in
1163** order to verify that SQLite recovers gracefully from such
1164** conditions.
1165**
1166** The xMalloc, xFree, and xRealloc methods must work like the
1167** malloc(), free(), and realloc() functions from the standard library.
1168**
1169** xSize should return the allocated size of a memory allocation
1170** previously obtained from xMalloc or xRealloc.  The allocated size
1171** is always at least as big as the requested size but may be larger.
1172**
1173** The xRoundup method returns what would be the allocated size of
1174** a memory allocation given a particular requested size.  Most memory
1175** allocators round up memory allocations at least to the next multiple
1176** of 8.  Some allocators round up to a larger multiple or to a power of 2.
1177**
1178** The xInit method initializes the memory allocator.  (For example,
1179** it might allocate any require mutexes or initialize internal data
1180** structures.  The xShutdown method is invoked (indirectly) by
1181** [sqlite3_shutdown()] and should deallocate any resources acquired
1182** by xInit.  The pAppData pointer is used as the only parameter to
1183** xInit and xShutdown.
1184*/
1185typedef struct sqlite3_mem_methods sqlite3_mem_methods;
1186struct sqlite3_mem_methods {
1187  void *(*xMalloc)(int);         /* Memory allocation function */
1188  void (*xFree)(void*);          /* Free a prior allocation */
1189  void *(*xRealloc)(void*,int);  /* Resize an allocation */
1190  int (*xSize)(void*);           /* Return the size of an allocation */
1191  int (*xRoundup)(int);          /* Round up request size to allocation size */
1192  int (*xInit)(void*);           /* Initialize the memory allocator */
1193  void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
1194  void *pAppData;                /* Argument to xInit() and xShutdown() */
1195};
1196
1197/*
1198** CAPI3REF: Configuration Options {H10160} <S20000>
1199** EXPERIMENTAL
1200**
1201** These constants are the available integer configuration options that
1202** can be passed as the first argument to the [sqlite3_config()] interface.
1203**
1204** New configuration options may be added in future releases of SQLite.
1205** Existing configuration options might be discontinued.  Applications
1206** should check the return code from [sqlite3_config()] to make sure that
1207** the call worked.  The [sqlite3_config()] interface will return a
1208** non-zero [error code] if a discontinued or unsupported configuration option
1209** is invoked.
1210**
1211** <dl>
1212** <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
1213** <dd>There are no arguments to this option.  This option disables
1214** all mutexing and puts SQLite into a mode where it can only be used
1215** by a single thread.</dd>
1216**
1217** <dt>SQLITE_CONFIG_MULTITHREAD</dt>
1218** <dd>There are no arguments to this option.  This option disables
1219** mutexing on [database connection] and [prepared statement] objects.
1220** The application is responsible for serializing access to
1221** [database connections] and [prepared statements].  But other mutexes
1222** are enabled so that SQLite will be safe to use in a multi-threaded
1223** environment as long as no two threads attempt to use the same
1224** [database connection] at the same time.  See the [threading mode]
1225** documentation for additional information.</dd>
1226**
1227** <dt>SQLITE_CONFIG_SERIALIZED</dt>
1228** <dd>There are no arguments to this option.  This option enables
1229** all mutexes including the recursive
1230** mutexes on [database connection] and [prepared statement] objects.
1231** In this mode (which is the default when SQLite is compiled with
1232** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
1233** to [database connections] and [prepared statements] so that the
1234** application is free to use the same [database connection] or the
1235** same [prepared statement] in different threads at the same time.
1236** See the [threading mode] documentation for additional information.</dd>
1237**
1238** <dt>SQLITE_CONFIG_MALLOC</dt>
1239** <dd>This option takes a single argument which is a pointer to an
1240** instance of the [sqlite3_mem_methods] structure.  The argument specifies
1241** alternative low-level memory allocation routines to be used in place of
1242** the memory allocation routines built into SQLite.</dd>
1243**
1244** <dt>SQLITE_CONFIG_GETMALLOC</dt>
1245** <dd>This option takes a single argument which is a pointer to an
1246** instance of the [sqlite3_mem_methods] structure.  The [sqlite3_mem_methods]
1247** structure is filled with the currently defined memory allocation routines.
1248** This option can be used to overload the default memory allocation
1249** routines with a wrapper that simulations memory allocation failure or
1250** tracks memory usage, for example.</dd>
1251**
1252** <dt>SQLITE_CONFIG_MEMSTATUS</dt>
1253** <dd>This option takes single argument of type int, interpreted as a
1254** boolean, which enables or disables the collection of memory allocation
1255** statistics. When disabled, the following SQLite interfaces become
1256** non-operational:
1257**   <ul>
1258**   <li> [sqlite3_memory_used()]
1259**   <li> [sqlite3_memory_highwater()]
1260**   <li> [sqlite3_soft_heap_limit()]
1261**   <li> [sqlite3_status()]
1262**   </ul>
1263** </dd>
1264**
1265** <dt>SQLITE_CONFIG_SCRATCH</dt>
1266** <dd>This option specifies a static memory buffer that SQLite can use for
1267** scratch memory.  There are three arguments:  A pointer to the memory, the
1268** size of each scratch buffer (sz), and the number of buffers (N).  The sz
1269** argument must be a multiple of 16. The sz parameter should be a few bytes
1270** larger than the actual scratch space required due internal overhead.
1271** The first
1272** argument should point to an allocation of at least sz*N bytes of memory.
1273** SQLite will use no more than one scratch buffer at once per thread, so
1274** N should be set to the expected maximum number of threads.  The sz
1275** parameter should be 6 times the size of the largest database page size.
1276** Scratch buffers are used as part of the btree balance operation.  If
1277** The btree balancer needs additional memory beyond what is provided by
1278** scratch buffers or if no scratch buffer space is specified, then SQLite
1279** goes to [sqlite3_malloc()] to obtain the memory it needs.</dd>
1280**
1281** <dt>SQLITE_CONFIG_PAGECACHE</dt>
1282** <dd>This option specifies a static memory buffer that SQLite can use for
1283** the database page cache with the default page cache implemenation.
1284** This configuration should not be used if an application-define page
1285** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option.
1286** There are three arguments to this option: A pointer to the
1287** memory, the size of each page buffer (sz), and the number of pages (N).
1288** The sz argument must be a power of two between 512 and 32768.  The first
1289** argument should point to an allocation of at least sz*N bytes of memory.
1290** SQLite will use the memory provided by the first argument to satisfy its
1291** memory needs for the first N pages that it adds to cache.  If additional
1292** page cache memory is needed beyond what is provided by this option, then
1293** SQLite goes to [sqlite3_malloc()] for the additional storage space.
1294** The implementation might use one or more of the N buffers to hold
1295** memory accounting information. </dd>
1296**
1297** <dt>SQLITE_CONFIG_HEAP</dt>
1298** <dd>This option specifies a static memory buffer that SQLite will use
1299** for all of its dynamic memory allocation needs beyond those provided
1300** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
1301** There are three arguments: A pointer to the memory, the number of
1302** bytes in the memory buffer, and the minimum allocation size.  If
1303** the first pointer (the memory pointer) is NULL, then SQLite reverts
1304** to using its default memory allocator (the system malloc() implementation),
1305** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  If the
1306** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
1307** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
1308** allocator is engaged to handle all of SQLites memory allocation needs.</dd>
1309**
1310** <dt>SQLITE_CONFIG_MUTEX</dt>
1311** <dd>This option takes a single argument which is a pointer to an
1312** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
1313** alternative low-level mutex routines to be used in place
1314** the mutex routines built into SQLite.</dd>
1315**
1316** <dt>SQLITE_CONFIG_GETMUTEX</dt>
1317** <dd>This option takes a single argument which is a pointer to an
1318** instance of the [sqlite3_mutex_methods] structure.  The
1319** [sqlite3_mutex_methods]
1320** structure is filled with the currently defined mutex routines.
1321** This option can be used to overload the default mutex allocation
1322** routines with a wrapper used to track mutex usage for performance
1323** profiling or testing, for example.</dd>
1324**
1325** <dt>SQLITE_CONFIG_LOOKASIDE</dt>
1326** <dd>This option takes two arguments that determine the default
1327** memory allcation lookaside optimization.  The first argument is the
1328** size of each lookaside buffer slot and the second is the number of
1329** slots allocated to each database connection.</dd>
1330**
1331** <dt>SQLITE_CONFIG_PCACHE</dt>
1332** <dd>This option takes a single argument which is a pointer to
1333** an [sqlite3_pcache_methods] object.  This object specifies the interface
1334** to a custom page cache implementation.  SQLite makes a copy of the
1335** object and uses it for page cache memory allocations.</dd>
1336**
1337** <dt>SQLITE_CONFIG_GETPCACHE</dt>
1338** <dd>This option takes a single argument which is a pointer to an
1339** [sqlite3_pcache_methods] object.  SQLite copies of the current
1340** page cache implementation into that object.</dd>
1341**
1342** </dl>
1343*/
1344#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
1345#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
1346#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
1347#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
1348#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
1349#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
1350#define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
1351#define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
1352#define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
1353#define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
1354#define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
1355/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */
1356#define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
1357#define SQLITE_CONFIG_PCACHE       14  /* sqlite3_pcache_methods* */
1358#define SQLITE_CONFIG_GETPCACHE    15  /* sqlite3_pcache_methods* */
1359
1360/*
1361** CAPI3REF: Configuration Options {H10170} <S20000>
1362** EXPERIMENTAL
1363**
1364** These constants are the available integer configuration options that
1365** can be passed as the second argument to the [sqlite3_db_config()] interface.
1366**
1367** New configuration options may be added in future releases of SQLite.
1368** Existing configuration options might be discontinued.  Applications
1369** should check the return code from [sqlite3_db_config()] to make sure that
1370** the call worked.  The [sqlite3_db_config()] interface will return a
1371** non-zero [error code] if a discontinued or unsupported configuration option
1372** is invoked.
1373**
1374** <dl>
1375** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
1376** <dd>This option takes three additional arguments that determine the
1377** [lookaside memory allocator] configuration for the [database connection].
1378** The first argument (the third parameter to [sqlite3_db_config()] is a
1379** pointer to a memory buffer to use for lookaside memory.  The first
1380** argument may be NULL in which case SQLite will allocate the lookaside
1381** buffer itself using [sqlite3_malloc()].  The second argument is the
1382** size of each lookaside buffer slot and the third argument is the number of
1383** slots.  The size of the buffer in the first argument must be greater than
1384** or equal to the product of the second and third arguments.</dd>
1385**
1386** </dl>
1387*/
1388#define SQLITE_DBCONFIG_LOOKASIDE    1001  /* void* int int */
1389
1390
1391/*
1392** CAPI3REF: Enable Or Disable Extended Result Codes {H12200} <S10700>
1393**
1394** The sqlite3_extended_result_codes() routine enables or disables the
1395** [extended result codes] feature of SQLite. The extended result
1396** codes are disabled by default for historical compatibility considerations.
1397**
1398** INVARIANTS:
1399**
1400** {H12201} Each new [database connection] shall have the
1401**          [extended result codes] feature disabled by default.
1402**
1403** {H12202} The [sqlite3_extended_result_codes(D,F)] interface shall enable
1404**          [extended result codes] for the  [database connection] D
1405**          if the F parameter is true, or disable them if F is false.
1406*/
1407int sqlite3_extended_result_codes(sqlite3*, int onoff);
1408
1409/*
1410** CAPI3REF: Last Insert Rowid {H12220} <S10700>
1411**
1412** Each entry in an SQLite table has a unique 64-bit signed
1413** integer key called the [ROWID | "rowid"]. The rowid is always available
1414** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
1415** names are not also used by explicitly declared columns. If
1416** the table has a column of type [INTEGER PRIMARY KEY] then that column
1417** is another alias for the rowid.
1418**
1419** This routine returns the [rowid] of the most recent
1420** successful [INSERT] into the database from the [database connection]
1421** in the first argument.  If no successful [INSERT]s
1422** have ever occurred on that database connection, zero is returned.
1423**
1424** If an [INSERT] occurs within a trigger, then the [rowid] of the inserted
1425** row is returned by this routine as long as the trigger is running.
1426** But once the trigger terminates, the value returned by this routine
1427** reverts to the last value inserted before the trigger fired.
1428**
1429** An [INSERT] that fails due to a constraint violation is not a
1430** successful [INSERT] and does not change the value returned by this
1431** routine.  Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
1432** and INSERT OR ABORT make no changes to the return value of this
1433** routine when their insertion fails.  When INSERT OR REPLACE
1434** encounters a constraint violation, it does not fail.  The
1435** INSERT continues to completion after deleting rows that caused
1436** the constraint problem so INSERT OR REPLACE will always change
1437** the return value of this interface.
1438**
1439** For the purposes of this routine, an [INSERT] is considered to
1440** be successful even if it is subsequently rolled back.
1441**
1442** INVARIANTS:
1443**
1444** {H12221} The [sqlite3_last_insert_rowid()] function shall return
1445**          the [rowid]
1446**          of the most recent successful [INSERT] performed on the same
1447**          [database connection] and within the same or higher level
1448**          trigger context, or zero if there have been no qualifying
1449**          [INSERT] statements.
1450**
1451** {H12223} The [sqlite3_last_insert_rowid()] function shall return the
1452**          same value when called from the same trigger context
1453**          immediately before and after a [ROLLBACK].
1454**
1455** ASSUMPTIONS:
1456**
1457** {A12232} If a separate thread performs a new [INSERT] on the same
1458**          database connection while the [sqlite3_last_insert_rowid()]
1459**          function is running and thus changes the last insert [rowid],
1460**          then the value returned by [sqlite3_last_insert_rowid()] is
1461**          unpredictable and might not equal either the old or the new
1462**          last insert [rowid].
1463*/
1464sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
1465
1466/*
1467** CAPI3REF: Count The Number Of Rows Modified {H12240} <S10600>
1468**
1469** This function returns the number of database rows that were changed
1470** or inserted or deleted by the most recently completed SQL statement
1471** on the [database connection] specified by the first parameter.
1472** Only changes that are directly specified by the [INSERT], [UPDATE],
1473** or [DELETE] statement are counted.  Auxiliary changes caused by
1474** triggers are not counted. Use the [sqlite3_total_changes()] function
1475** to find the total number of changes including changes caused by triggers.
1476**
1477** A "row change" is a change to a single row of a single table
1478** caused by an INSERT, DELETE, or UPDATE statement.  Rows that
1479** are changed as side effects of REPLACE constraint resolution,
1480** rollback, ABORT processing, DROP TABLE, or by any other
1481** mechanisms do not count as direct row changes.
1482**
1483** A "trigger context" is a scope of execution that begins and
1484** ends with the script of a trigger.  Most SQL statements are
1485** evaluated outside of any trigger.  This is the "top level"
1486** trigger context.  If a trigger fires from the top level, a
1487** new trigger context is entered for the duration of that one
1488** trigger.  Subtriggers create subcontexts for their duration.
1489**
1490** Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
1491** not create a new trigger context.
1492**
1493** This function returns the number of direct row changes in the
1494** most recent INSERT, UPDATE, or DELETE statement within the same
1495** trigger context.
1496**
1497** Thus, when called from the top level, this function returns the
1498** number of changes in the most recent INSERT, UPDATE, or DELETE
1499** that also occurred at the top level.  Within the body of a trigger,
1500** the sqlite3_changes() interface can be called to find the number of
1501** changes in the most recently completed INSERT, UPDATE, or DELETE
1502** statement within the body of the same trigger.
1503** However, the number returned does not include changes
1504** caused by subtriggers since those have their own context.
1505**
1506** SQLite implements the command "DELETE FROM table" without a WHERE clause
1507** by dropping and recreating the table.  Doing so is much faster than going
1508** through and deleting individual elements from the table.  Because of this
1509** optimization, the deletions in "DELETE FROM table" are not row changes and
1510** will not be counted by the sqlite3_changes() or [sqlite3_total_changes()]
1511** functions, regardless of the number of elements that were originally
1512** in the table.  To get an accurate count of the number of rows deleted, use
1513** "DELETE FROM table WHERE 1" instead.  Or recompile using the
1514** [SQLITE_OMIT_TRUNCATE_OPTIMIZATION] compile-time option to disable the
1515** optimization on all queries.
1516**
1517** INVARIANTS:
1518**
1519** {H12241} The [sqlite3_changes()] function shall return the number of
1520**          row changes caused by the most recent INSERT, UPDATE,
1521**          or DELETE statement on the same database connection and
1522**          within the same or higher trigger context, or zero if there have
1523**          not been any qualifying row changes.
1524**
1525** {H12243} Statements of the form "DELETE FROM tablename" with no
1526**          WHERE clause shall cause subsequent calls to
1527**          [sqlite3_changes()] to return zero, regardless of the
1528**          number of rows originally in the table.
1529**
1530** ASSUMPTIONS:
1531**
1532** {A12252} If a separate thread makes changes on the same database connection
1533**          while [sqlite3_changes()] is running then the value returned
1534**          is unpredictable and not meaningful.
1535*/
1536int sqlite3_changes(sqlite3*);
1537
1538/*
1539** CAPI3REF: Total Number Of Rows Modified {H12260} <S10600>
1540**
1541** This function returns the number of row changes caused by INSERT,
1542** UPDATE or DELETE statements since the [database connection] was opened.
1543** The count includes all changes from all trigger contexts.  However,
1544** the count does not include changes used to implement REPLACE constraints,
1545** do rollbacks or ABORT processing, or DROP table processing.
1546** The changes are counted as soon as the statement that makes them is
1547** completed (when the statement handle is passed to [sqlite3_reset()] or
1548** [sqlite3_finalize()]).
1549**
1550** SQLite implements the command "DELETE FROM table" without a WHERE clause
1551** by dropping and recreating the table.  (This is much faster than going
1552** through and deleting individual elements from the table.)  Because of this
1553** optimization, the deletions in "DELETE FROM table" are not row changes and
1554** will not be counted by the sqlite3_changes() or [sqlite3_total_changes()]
1555** functions, regardless of the number of elements that were originally
1556** in the table.  To get an accurate count of the number of rows deleted, use
1557** "DELETE FROM table WHERE 1" instead.   Or recompile using the
1558** [SQLITE_OMIT_TRUNCATE_OPTIMIZATION] compile-time option to disable the
1559** optimization on all queries.
1560**
1561** See also the [sqlite3_changes()] interface.
1562**
1563** INVARIANTS:
1564**
1565** {H12261} The [sqlite3_total_changes()] returns the total number
1566**          of row changes caused by INSERT, UPDATE, and/or DELETE
1567**          statements on the same [database connection], in any
1568**          trigger context, since the database connection was created.
1569**
1570** {H12263} Statements of the form "DELETE FROM tablename" with no
1571**          WHERE clause shall not change the value returned
1572**          by [sqlite3_total_changes()].
1573**
1574** ASSUMPTIONS:
1575**
1576** {A12264} If a separate thread makes changes on the same database connection
1577**          while [sqlite3_total_changes()] is running then the value
1578**          returned is unpredictable and not meaningful.
1579*/
1580int sqlite3_total_changes(sqlite3*);
1581
1582/*
1583** CAPI3REF: Interrupt A Long-Running Query {H12270} <S30500>
1584**
1585** This function causes any pending database operation to abort and
1586** return at its earliest opportunity. This routine is typically
1587** called in response to a user action such as pressing "Cancel"
1588** or Ctrl-C where the user wants a long query operation to halt
1589** immediately.
1590**
1591** It is safe to call this routine from a thread different from the
1592** thread that is currently running the database operation.  But it
1593** is not safe to call this routine with a [database connection] that
1594** is closed or might close before sqlite3_interrupt() returns.
1595**
1596** If an SQL operation is very nearly finished at the time when
1597** sqlite3_interrupt() is called, then it might not have an opportunity
1598** to be interrupted and might continue to completion.
1599**
1600** An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
1601** If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
1602** that is inside an explicit transaction, then the entire transaction
1603** will be rolled back automatically.
1604**
1605** A call to sqlite3_interrupt() has no effect on SQL statements
1606** that are started after sqlite3_interrupt() returns.
1607**
1608** INVARIANTS:
1609**
1610** {H12271} The [sqlite3_interrupt()] interface will force all running
1611**          SQL statements associated with the same database connection
1612**          to halt after processing at most one additional row of data.
1613**
1614** {H12272} Any SQL statement that is interrupted by [sqlite3_interrupt()]
1615**          will return [SQLITE_INTERRUPT].
1616**
1617** ASSUMPTIONS:
1618**
1619** {A12279} If the database connection closes while [sqlite3_interrupt()]
1620**          is running then bad things will likely happen.
1621*/
1622void sqlite3_interrupt(sqlite3*);
1623
1624/*
1625** CAPI3REF: Determine If An SQL Statement Is Complete {H10510} <S70200>
1626**
1627** These routines are useful for command-line input to determine if the
1628** currently entered text seems to form complete a SQL statement or
1629** if additional input is needed before sending the text into
1630** SQLite for parsing.  These routines return true if the input string
1631** appears to be a complete SQL statement.  A statement is judged to be
1632** complete if it ends with a semicolon token and is not a fragment of a
1633** CREATE TRIGGER statement.  Semicolons that are embedded within
1634** string literals or quoted identifier names or comments are not
1635** independent tokens (they are part of the token in which they are
1636** embedded) and thus do not count as a statement terminator.
1637**
1638** These routines do not parse the SQL statements thus
1639** will not detect syntactically incorrect SQL.
1640**
1641** INVARIANTS:
1642**
1643** {H10511} A successful evaluation of [sqlite3_complete()] or
1644**          [sqlite3_complete16()] functions shall
1645**          return a numeric 1 if and only if the last non-whitespace
1646**          token in their input is a semicolon that is not in between
1647**          the BEGIN and END of a CREATE TRIGGER statement.
1648**
1649** {H10512} If a memory allocation error occurs during an invocation
1650**          of [sqlite3_complete()] or [sqlite3_complete16()] then the
1651**          routine shall return [SQLITE_NOMEM].
1652**
1653** ASSUMPTIONS:
1654**
1655** {A10512} The input to [sqlite3_complete()] must be a zero-terminated
1656**          UTF-8 string.
1657**
1658** {A10513} The input to [sqlite3_complete16()] must be a zero-terminated
1659**          UTF-16 string in native byte order.
1660*/
1661int sqlite3_complete(const char *sql);
1662int sqlite3_complete16(const void *sql);
1663
1664/*
1665** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors {H12310} <S40400>
1666**
1667** This routine sets a callback function that might be invoked whenever
1668** an attempt is made to open a database table that another thread
1669** or process has locked.
1670**
1671** If the busy callback is NULL, then [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED]
1672** is returned immediately upon encountering the lock. If the busy callback
1673** is not NULL, then the callback will be invoked with two arguments.
1674**
1675** The first argument to the handler is a copy of the void* pointer which
1676** is the third argument to sqlite3_busy_handler().  The second argument to
1677** the handler callback is the number of times that the busy handler has
1678** been invoked for this locking event.  If the
1679** busy callback returns 0, then no additional attempts are made to
1680** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned.
1681** If the callback returns non-zero, then another attempt
1682** is made to open the database for reading and the cycle repeats.
1683**
1684** The presence of a busy handler does not guarantee that it will be invoked
1685** when there is lock contention. If SQLite determines that invoking the busy
1686** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
1687** or [SQLITE_IOERR_BLOCKED] instead of invoking the busy handler.
1688** Consider a scenario where one process is holding a read lock that
1689** it is trying to promote to a reserved lock and
1690** a second process is holding a reserved lock that it is trying
1691** to promote to an exclusive lock.  The first process cannot proceed
1692** because it is blocked by the second and the second process cannot
1693** proceed because it is blocked by the first.  If both processes
1694** invoke the busy handlers, neither will make any progress.  Therefore,
1695** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
1696** will induce the first process to release its read lock and allow
1697** the second process to proceed.
1698**
1699** The default busy callback is NULL.
1700**
1701** The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED]
1702** when SQLite is in the middle of a large transaction where all the
1703** changes will not fit into the in-memory cache.  SQLite will
1704** already hold a RESERVED lock on the database file, but it needs
1705** to promote this lock to EXCLUSIVE so that it can spill cache
1706** pages into the database file without harm to concurrent
1707** readers.  If it is unable to promote the lock, then the in-memory
1708** cache will be left in an inconsistent state and so the error
1709** code is promoted from the relatively benign [SQLITE_BUSY] to
1710** the more severe [SQLITE_IOERR_BLOCKED].  This error code promotion
1711** forces an automatic rollback of the changes.  See the
1712** <a href="/cvstrac/wiki?p=CorruptionFollowingBusyError">
1713** CorruptionFollowingBusyError</a> wiki page for a discussion of why
1714** this is important.
1715**
1716** There can only be a single busy handler defined for each
1717** [database connection].  Setting a new busy handler clears any
1718** previously set handler.  Note that calling [sqlite3_busy_timeout()]
1719** will also set or clear the busy handler.
1720**
1721** The busy callback should not take any actions which modify the
1722** database connection that invoked the busy handler.  Any such actions
1723** result in undefined behavior.
1724**
1725** INVARIANTS:
1726**
1727** {H12311} The [sqlite3_busy_handler(D,C,A)] function shall replace
1728**          busy callback in the [database connection] D with a new
1729**          a new busy handler C and application data pointer A.
1730**
1731** {H12312} Newly created [database connections] shall have a busy
1732**          handler of NULL.
1733**
1734** {H12314} When two or more [database connections] share a
1735**          [sqlite3_enable_shared_cache | common cache],
1736**          the busy handler for the database connection currently using
1737**          the cache shall be invoked when the cache encounters a lock.
1738**
1739** {H12316} If a busy handler callback returns zero, then the SQLite interface
1740**          that provoked the locking event shall return [SQLITE_BUSY].
1741**
1742** {H12318} SQLite shall invokes the busy handler with two arguments which
1743**          are a copy of the pointer supplied by the 3rd parameter to
1744**          [sqlite3_busy_handler()] and a count of the number of prior
1745**          invocations of the busy handler for the same locking event.
1746**
1747** ASSUMPTIONS:
1748**
1749** {A12319} A busy handler must not close the database connection
1750**          or [prepared statement] that invoked the busy handler.
1751*/
1752int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);
1753
1754/*
1755** CAPI3REF: Set A Busy Timeout {H12340} <S40410>
1756**
1757** This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
1758** for a specified amount of time when a table is locked.  The handler
1759** will sleep multiple times until at least "ms" milliseconds of sleeping
1760** have accumulated. {H12343} After "ms" milliseconds of sleeping,
1761** the handler returns 0 which causes [sqlite3_step()] to return
1762** [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED].
1763**
1764** Calling this routine with an argument less than or equal to zero
1765** turns off all busy handlers.
1766**
1767** There can only be a single busy handler for a particular
1768** [database connection] any any given moment.  If another busy handler
1769** was defined  (using [sqlite3_busy_handler()]) prior to calling
1770** this routine, that other busy handler is cleared.
1771**
1772** INVARIANTS:
1773**
1774** {H12341} The [sqlite3_busy_timeout()] function shall override any prior
1775**          [sqlite3_busy_timeout()] or [sqlite3_busy_handler()] setting
1776**          on the same [database connection].
1777**
1778** {H12343} If the 2nd parameter to [sqlite3_busy_timeout()] is less than
1779**          or equal to zero, then the busy handler shall be cleared so that
1780**          all subsequent locking events immediately return [SQLITE_BUSY].
1781**
1782** {H12344} If the 2nd parameter to [sqlite3_busy_timeout()] is a positive
1783**          number N, then a busy handler shall be set that repeatedly calls
1784**          the xSleep() method in the [sqlite3_vfs | VFS interface] until
1785**          either the lock clears or until the cumulative sleep time
1786**          reported back by xSleep() exceeds N milliseconds.
1787*/
1788int sqlite3_busy_timeout(sqlite3*, int ms);
1789
1790/*
1791** CAPI3REF: Convenience Routines For Running Queries {H12370} <S10000>
1792**
1793** Definition: A <b>result table</b> is memory data structure created by the
1794** [sqlite3_get_table()] interface.  A result table records the
1795** complete query results from one or more queries.
1796**
1797** The table conceptually has a number of rows and columns.  But
1798** these numbers are not part of the result table itself.  These
1799** numbers are obtained separately.  Let N be the number of rows
1800** and M be the number of columns.
1801**
1802** A result table is an array of pointers to zero-terminated UTF-8 strings.
1803** There are (N+1)*M elements in the array.  The first M pointers point
1804** to zero-terminated strings that  contain the names of the columns.
1805** The remaining entries all point to query results.  NULL values result
1806** in NULL pointers.  All other values are in their UTF-8 zero-terminated
1807** string representation as returned by [sqlite3_column_text()].
1808**
1809** A result table might consist of one or more memory allocations.
1810** It is not safe to pass a result table directly to [sqlite3_free()].
1811** A result table should be deallocated using [sqlite3_free_table()].
1812**
1813** As an example of the result table format, suppose a query result
1814** is as follows:
1815**
1816** <blockquote><pre>
1817**        Name        | Age
1818**        -----------------------
1819**        Alice       | 43
1820**        Bob         | 28
1821**        Cindy       | 21
1822** </pre></blockquote>
1823**
1824** There are two column (M==2) and three rows (N==3).  Thus the
1825** result table has 8 entries.  Suppose the result table is stored
1826** in an array names azResult.  Then azResult holds this content:
1827**
1828** <blockquote><pre>
1829**        azResult&#91;0] = "Name";
1830**        azResult&#91;1] = "Age";
1831**        azResult&#91;2] = "Alice";
1832**        azResult&#91;3] = "43";
1833**        azResult&#91;4] = "Bob";
1834**        azResult&#91;5] = "28";
1835**        azResult&#91;6] = "Cindy";
1836**        azResult&#91;7] = "21";
1837** </pre></blockquote>
1838**
1839** The sqlite3_get_table() function evaluates one or more
1840** semicolon-separated SQL statements in the zero-terminated UTF-8
1841** string of its 2nd parameter.  It returns a result table to the
1842** pointer given in its 3rd parameter.
1843**
1844** After the calling function has finished using the result, it should
1845** pass the pointer to the result table to sqlite3_free_table() in order to
1846** release the memory that was malloced.  Because of the way the
1847** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
1848** function must not try to call [sqlite3_free()] directly.  Only
1849** [sqlite3_free_table()] is able to release the memory properly and safely.
1850**
1851** The sqlite3_get_table() interface is implemented as a wrapper around
1852** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
1853** to any internal data structures of SQLite.  It uses only the public
1854** interface defined here.  As a consequence, errors that occur in the
1855** wrapper layer outside of the internal [sqlite3_exec()] call are not
1856** reflected in subsequent calls to [sqlite3_errcode()] or [sqlite3_errmsg()].
1857**
1858** INVARIANTS:
1859**
1860** {H12371} If a [sqlite3_get_table()] fails a memory allocation, then
1861**          it shall free the result table under construction, abort the
1862**          query in process, skip any subsequent queries, set the
1863**          *pazResult output pointer to NULL and return [SQLITE_NOMEM].
1864**
1865** {H12373} If the pnColumn parameter to [sqlite3_get_table()] is not NULL
1866**          then a successful invocation of [sqlite3_get_table()] shall
1867**          write the number of columns in the
1868**          result set of the query into *pnColumn.
1869**
1870** {H12374} If the pnRow parameter to [sqlite3_get_table()] is not NULL
1871**          then a successful invocation of [sqlite3_get_table()] shall
1872**          writes the number of rows in the
1873**          result set of the query into *pnRow.
1874**
1875** {H12376} A successful invocation of [sqlite3_get_table()] that computes
1876**          N rows of result with C columns per row shall make *pazResult
1877**          point to an array of pointers to (N+1)*C strings where the first
1878**          C strings are column names as obtained from
1879**          [sqlite3_column_name()] and the rest are column result values
1880**          obtained from [sqlite3_column_text()].
1881**
1882** {H12379} The values in the pazResult array returned by [sqlite3_get_table()]
1883**          shall remain valid until cleared by [sqlite3_free_table()].
1884**
1885** {H12382} When an error occurs during evaluation of [sqlite3_get_table()]
1886**          the function shall set *pazResult to NULL, write an error message
1887**          into memory obtained from [sqlite3_malloc()], make
1888**          **pzErrmsg point to that error message, and return a
1889**          appropriate [error code].
1890*/
1891int sqlite3_get_table(
1892  sqlite3 *db,          /* An open database */
1893  const char *zSql,     /* SQL to be evaluated */
1894  char ***pazResult,    /* Results of the query */
1895  int *pnRow,           /* Number of result rows written here */
1896  int *pnColumn,        /* Number of result columns written here */
1897  char **pzErrmsg       /* Error msg written here */
1898);
1899void sqlite3_free_table(char **result);
1900
1901/*
1902** CAPI3REF: Formatted String Printing Functions {H17400} <S70000><S20000>
1903**
1904** These routines are workalikes of the "printf()" family of functions
1905** from the standard C library.
1906**
1907** The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
1908** results into memory obtained from [sqlite3_malloc()].
1909** The strings returned by these two routines should be
1910** released by [sqlite3_free()].  Both routines return a
1911** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
1912** memory to hold the resulting string.
1913**
1914** In sqlite3_snprintf() routine is similar to "snprintf()" from
1915** the standard C library.  The result is written into the
1916** buffer supplied as the second parameter whose size is given by
1917** the first parameter. Note that the order of the
1918** first two parameters is reversed from snprintf().  This is an
1919** historical accident that cannot be fixed without breaking
1920** backwards compatibility.  Note also that sqlite3_snprintf()
1921** returns a pointer to its buffer instead of the number of
1922** characters actually written into the buffer.  We admit that
1923** the number of characters written would be a more useful return
1924** value but we cannot change the implementation of sqlite3_snprintf()
1925** now without breaking compatibility.
1926**
1927** As long as the buffer size is greater than zero, sqlite3_snprintf()
1928** guarantees that the buffer is always zero-terminated.  The first
1929** parameter "n" is the total size of the buffer, including space for
1930** the zero terminator.  So the longest string that can be completely
1931** written will be n-1 characters.
1932**
1933** These routines all implement some additional formatting
1934** options that are useful for constructing SQL statements.
1935** All of the usual printf() formatting options apply.  In addition, there
1936** is are "%q", "%Q", and "%z" options.
1937**
1938** The %q option works like %s in that it substitutes a null-terminated
1939** string from the argument list.  But %q also doubles every '\'' character.
1940** %q is designed for use inside a string literal.  By doubling each '\''
1941** character it escapes that character and allows it to be inserted into
1942** the string.
1943**
1944** For example, assume the string variable zText contains text as follows:
1945**
1946** <blockquote><pre>
1947**  char *zText = "It's a happy day!";
1948** </pre></blockquote>
1949**
1950** One can use this text in an SQL statement as follows:
1951**
1952** <blockquote><pre>
1953**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
1954**  sqlite3_exec(db, zSQL, 0, 0, 0);
1955**  sqlite3_free(zSQL);
1956** </pre></blockquote>
1957**
1958** Because the %q format string is used, the '\'' character in zText
1959** is escaped and the SQL generated is as follows:
1960**
1961** <blockquote><pre>
1962**  INSERT INTO table1 VALUES('It''s a happy day!')
1963** </pre></blockquote>
1964**
1965** This is correct.  Had we used %s instead of %q, the generated SQL
1966** would have looked like this:
1967**
1968** <blockquote><pre>
1969**  INSERT INTO table1 VALUES('It's a happy day!');
1970** </pre></blockquote>
1971**
1972** This second example is an SQL syntax error.  As a general rule you should
1973** always use %q instead of %s when inserting text into a string literal.
1974**
1975** The %Q option works like %q except it also adds single quotes around
1976** the outside of the total string.  Additionally, if the parameter in the
1977** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
1978** single quotes) in place of the %Q option.  So, for example, one could say:
1979**
1980** <blockquote><pre>
1981**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
1982**  sqlite3_exec(db, zSQL, 0, 0, 0);
1983**  sqlite3_free(zSQL);
1984** </pre></blockquote>
1985**
1986** The code above will render a correct SQL statement in the zSQL
1987** variable even if the zText variable is a NULL pointer.
1988**
1989** The "%z" formatting option works exactly like "%s" with the
1990** addition that after the string has been read and copied into
1991** the result, [sqlite3_free()] is called on the input string. {END}
1992**
1993** INVARIANTS:
1994**
1995** {H17403}  The [sqlite3_mprintf()] and [sqlite3_vmprintf()] interfaces
1996**           return either pointers to zero-terminated UTF-8 strings held in
1997**           memory obtained from [sqlite3_malloc()] or NULL pointers if
1998**           a call to [sqlite3_malloc()] fails.
1999**
2000** {H17406}  The [sqlite3_snprintf()] interface writes a zero-terminated
2001**           UTF-8 string into the buffer pointed to by the second parameter
2002**           provided that the first parameter is greater than zero.
2003**
2004** {H17407}  The [sqlite3_snprintf()] interface does not write slots of
2005**           its output buffer (the second parameter) outside the range
2006**           of 0 through N-1 (where N is the first parameter)
2007**           regardless of the length of the string
2008**           requested by the format specification.
2009*/
2010char *sqlite3_mprintf(const char*,...);
2011char *sqlite3_vmprintf(const char*, va_list);
2012char *sqlite3_snprintf(int,char*,const char*, ...);
2013
2014/*
2015** CAPI3REF: Memory Allocation Subsystem {H17300} <S20000>
2016**
2017** The SQLite core  uses these three routines for all of its own
2018** internal memory allocation needs. "Core" in the previous sentence
2019** does not include operating-system specific VFS implementation.  The
2020** Windows VFS uses native malloc() and free() for some operations.
2021**
2022** The sqlite3_malloc() routine returns a pointer to a block
2023** of memory at least N bytes in length, where N is the parameter.
2024** If sqlite3_malloc() is unable to obtain sufficient free
2025** memory, it returns a NULL pointer.  If the parameter N to
2026** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
2027** a NULL pointer.
2028**
2029** Calling sqlite3_free() with a pointer previously returned
2030** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
2031** that it might be reused.  The sqlite3_free() routine is
2032** a no-op if is called with a NULL pointer.  Passing a NULL pointer
2033** to sqlite3_free() is harmless.  After being freed, memory
2034** should neither be read nor written.  Even reading previously freed
2035** memory might result in a segmentation fault or other severe error.
2036** Memory corruption, a segmentation fault, or other severe error
2037** might result if sqlite3_free() is called with a non-NULL pointer that
2038** was not obtained from sqlite3_malloc() or sqlite3_realloc().
2039**
2040** The sqlite3_realloc() interface attempts to resize a
2041** prior memory allocation to be at least N bytes, where N is the
2042** second parameter.  The memory allocation to be resized is the first
2043** parameter.  If the first parameter to sqlite3_realloc()
2044** is a NULL pointer then its behavior is identical to calling
2045** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc().
2046** If the second parameter to sqlite3_realloc() is zero or
2047** negative then the behavior is exactly the same as calling
2048** sqlite3_free(P) where P is the first parameter to sqlite3_realloc().
2049** sqlite3_realloc() returns a pointer to a memory allocation
2050** of at least N bytes in size or NULL if sufficient memory is unavailable.
2051** If M is the size of the prior allocation, then min(N,M) bytes
2052** of the prior allocation are copied into the beginning of buffer returned
2053** by sqlite3_realloc() and the prior allocation is freed.
2054** If sqlite3_realloc() returns NULL, then the prior allocation
2055** is not freed.
2056**
2057** The memory returned by sqlite3_malloc() and sqlite3_realloc()
2058** is always aligned to at least an 8 byte boundary. {END}
2059**
2060** The default implementation of the memory allocation subsystem uses
2061** the malloc(), realloc() and free() provided by the standard C library.
2062** {H17382} However, if SQLite is compiled with the
2063** SQLITE_MEMORY_SIZE=<i>NNN</i> C preprocessor macro (where <i>NNN</i>
2064** is an integer), then SQLite create a static array of at least
2065** <i>NNN</i> bytes in size and uses that array for all of its dynamic
2066** memory allocation needs. {END}  Additional memory allocator options
2067** may be added in future releases.
2068**
2069** In SQLite version 3.5.0 and 3.5.1, it was possible to define
2070** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
2071** implementation of these routines to be omitted.  That capability
2072** is no longer provided.  Only built-in memory allocators can be used.
2073**
2074** The Windows OS interface layer calls
2075** the system malloc() and free() directly when converting
2076** filenames between the UTF-8 encoding used by SQLite
2077** and whatever filename encoding is used by the particular Windows
2078** installation.  Memory allocation errors are detected, but
2079** they are reported back as [SQLITE_CANTOPEN] or
2080** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
2081**
2082** INVARIANTS:
2083**
2084** {H17303}  The [sqlite3_malloc(N)] interface returns either a pointer to
2085**           a newly checked-out block of at least N bytes of memory
2086**           that is 8-byte aligned, or it returns NULL if it is unable
2087**           to fulfill the request.
2088**
2089** {H17304}  The [sqlite3_malloc(N)] interface returns a NULL pointer if
2090**           N is less than or equal to zero.
2091**
2092** {H17305}  The [sqlite3_free(P)] interface releases memory previously
2093**           returned from [sqlite3_malloc()] or [sqlite3_realloc()],
2094**           making it available for reuse.
2095**
2096** {H17306}  A call to [sqlite3_free(NULL)] is a harmless no-op.
2097**
2098** {H17310}  A call to [sqlite3_realloc(0,N)] is equivalent to a call
2099**           to [sqlite3_malloc(N)].
2100**
2101** {H17312}  A call to [sqlite3_realloc(P,0)] is equivalent to a call
2102**           to [sqlite3_free(P)].
2103**
2104** {H17315}  The SQLite core uses [sqlite3_malloc()], [sqlite3_realloc()],
2105**           and [sqlite3_free()] for all of its memory allocation and
2106**           deallocation needs.
2107**
2108** {H17318}  The [sqlite3_realloc(P,N)] interface returns either a pointer
2109**           to a block of checked-out memory of at least N bytes in size
2110**           that is 8-byte aligned, or a NULL pointer.
2111**
2112** {H17321}  When [sqlite3_realloc(P,N)] returns a non-NULL pointer, it first
2113**           copies the first K bytes of content from P into the newly
2114**           allocated block, where K is the lesser of N and the size of
2115**           the buffer P.
2116**
2117** {H17322}  When [sqlite3_realloc(P,N)] returns a non-NULL pointer, it first
2118**           releases the buffer P.
2119**
2120** {H17323}  When [sqlite3_realloc(P,N)] returns NULL, the buffer P is
2121**           not modified or released.
2122**
2123** ASSUMPTIONS:
2124**
2125** {A17350}  The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
2126**           must be either NULL or else pointers obtained from a prior
2127**           invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
2128**           not yet been released.
2129**
2130** {A17351}  The application must not read or write any part of
2131**           a block of memory after it has been released using
2132**           [sqlite3_free()] or [sqlite3_realloc()].
2133*/
2134void *sqlite3_malloc(int);
2135void *sqlite3_realloc(void*, int);
2136void sqlite3_free(void*);
2137
2138/*
2139** CAPI3REF: Memory Allocator Statistics {H17370} <S30210>
2140**
2141** SQLite provides these two interfaces for reporting on the status
2142** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
2143** routines, which form the built-in memory allocation subsystem.
2144**
2145** INVARIANTS:
2146**
2147** {H17371} The [sqlite3_memory_used()] routine returns the number of bytes
2148**          of memory currently outstanding (malloced but not freed).
2149**
2150** {H17373} The [sqlite3_memory_highwater()] routine returns the maximum
2151**          value of [sqlite3_memory_used()] since the high-water mark
2152**          was last reset.
2153**
2154** {H17374} The values returned by [sqlite3_memory_used()] and
2155**          [sqlite3_memory_highwater()] include any overhead
2156**          added by SQLite in its implementation of [sqlite3_malloc()],
2157**          but not overhead added by the any underlying system library
2158**          routines that [sqlite3_malloc()] may call.
2159**
2160** {H17375} The memory high-water mark is reset to the current value of
2161**          [sqlite3_memory_used()] if and only if the parameter to
2162**          [sqlite3_memory_highwater()] is true.  The value returned
2163**          by [sqlite3_memory_highwater(1)] is the high-water mark
2164**          prior to the reset.
2165*/
2166sqlite3_int64 sqlite3_memory_used(void);
2167sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
2168
2169/*
2170** CAPI3REF: Pseudo-Random Number Generator {H17390} <S20000>
2171**
2172** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
2173** select random [ROWID | ROWIDs] when inserting new records into a table that
2174** already uses the largest possible [ROWID].  The PRNG is also used for
2175** the build-in random() and randomblob() SQL functions.  This interface allows
2176** applications to access the same PRNG for other purposes.
2177**
2178** A call to this routine stores N bytes of randomness into buffer P.
2179**
2180** The first time this routine is invoked (either internally or by
2181** the application) the PRNG is seeded using randomness obtained
2182** from the xRandomness method of the default [sqlite3_vfs] object.
2183** On all subsequent invocations, the pseudo-randomness is generated
2184** internally and without recourse to the [sqlite3_vfs] xRandomness
2185** method.
2186**
2187** INVARIANTS:
2188**
2189** {H17392} The [sqlite3_randomness(N,P)] interface writes N bytes of
2190**          high-quality pseudo-randomness into buffer P.
2191*/
2192void sqlite3_randomness(int N, void *P);
2193
2194/*
2195** CAPI3REF: Compile-Time Authorization Callbacks {H12500} <S70100>
2196**
2197** This routine registers a authorizer callback with a particular
2198** [database connection], supplied in the first argument.
2199** The authorizer callback is invoked as SQL statements are being compiled
2200** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
2201** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  At various
2202** points during the compilation process, as logic is being created
2203** to perform various actions, the authorizer callback is invoked to
2204** see if those actions are allowed.  The authorizer callback should
2205** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
2206** specific action but allow the SQL statement to continue to be
2207** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
2208** rejected with an error.  If the authorizer callback returns
2209** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
2210** then the [sqlite3_prepare_v2()] or equivalent call that triggered
2211** the authorizer will fail with an error message.
2212**
2213** When the callback returns [SQLITE_OK], that means the operation
2214** requested is ok.  When the callback returns [SQLITE_DENY], the
2215** [sqlite3_prepare_v2()] or equivalent call that triggered the
2216** authorizer will fail with an error message explaining that
2217** access is denied.  If the authorizer code is [SQLITE_READ]
2218** and the callback returns [SQLITE_IGNORE] then the
2219** [prepared statement] statement is constructed to substitute
2220** a NULL value in place of the table column that would have
2221** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
2222** return can be used to deny an untrusted user access to individual
2223** columns of a table.
2224**
2225** The first parameter to the authorizer callback is a copy of the third
2226** parameter to the sqlite3_set_authorizer() interface. The second parameter
2227** to the callback is an integer [SQLITE_COPY | action code] that specifies
2228** the particular action to be authorized. The third through sixth parameters
2229** to the callback are zero-terminated strings that contain additional
2230** details about the action to be authorized.
2231**
2232** An authorizer is used when [sqlite3_prepare | preparing]
2233** SQL statements from an untrusted source, to ensure that the SQL statements
2234** do not try to access data they are not allowed to see, or that they do not
2235** try to execute malicious statements that damage the database.  For
2236** example, an application may allow a user to enter arbitrary
2237** SQL queries for evaluation by a database.  But the application does
2238** not want the user to be able to make arbitrary changes to the
2239** database.  An authorizer could then be put in place while the
2240** user-entered SQL is being [sqlite3_prepare | prepared] that
2241** disallows everything except [SELECT] statements.
2242**
2243** Applications that need to process SQL from untrusted sources
2244** might also consider lowering resource limits using [sqlite3_limit()]
2245** and limiting database size using the [max_page_count] [PRAGMA]
2246** in addition to using an authorizer.
2247**
2248** Only a single authorizer can be in place on a database connection
2249** at a time.  Each call to sqlite3_set_authorizer overrides the
2250** previous call.  Disable the authorizer by installing a NULL callback.
2251** The authorizer is disabled by default.
2252**
2253** The authorizer callback must not do anything that will modify
2254** the database connection that invoked the authorizer callback.
2255** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
2256** database connections for the meaning of "modify" in this paragraph.
2257**
2258** When [sqlite3_prepare_v2()] is used to prepare a statement, the
2259** statement might be reprepared during [sqlite3_step()] due to a
2260** schema change.  Hence, the application should ensure that the
2261** correct authorizer callback remains in place during the [sqlite3_step()].
2262**
2263** Note that the authorizer callback is invoked only during
2264** [sqlite3_prepare()] or its variants.  Authorization is not
2265** performed during statement evaluation in [sqlite3_step()].
2266**
2267** INVARIANTS:
2268**
2269** {H12501} The [sqlite3_set_authorizer(D,...)] interface registers a
2270**          authorizer callback with database connection D.
2271**
2272** {H12502} The authorizer callback is invoked as SQL statements are
2273**          being parseed and compiled.
2274**
2275** {H12503} If the authorizer callback returns any value other than
2276**          [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY], then
2277**          the application interface call that caused
2278**          the authorizer callback to run shall fail with an
2279**          [SQLITE_ERROR] error code and an appropriate error message.
2280**
2281** {H12504} When the authorizer callback returns [SQLITE_OK], the operation
2282**          described is processed normally.
2283**
2284** {H12505} When the authorizer callback returns [SQLITE_DENY], the
2285**          application interface call that caused the
2286**          authorizer callback to run shall fail
2287**          with an [SQLITE_ERROR] error code and an error message
2288**          explaining that access is denied.
2289**
2290** {H12506} If the authorizer code (the 2nd parameter to the authorizer
2291**          callback) is [SQLITE_READ] and the authorizer callback returns
2292**          [SQLITE_IGNORE], then the prepared statement is constructed to
2293**          insert a NULL value in place of the table column that would have
2294**          been read if [SQLITE_OK] had been returned.
2295**
2296** {H12507} If the authorizer code (the 2nd parameter to the authorizer
2297**          callback) is anything other than [SQLITE_READ], then
2298**          a return of [SQLITE_IGNORE] has the same effect as [SQLITE_DENY].
2299**
2300** {H12510} The first parameter to the authorizer callback is a copy of
2301**          the third parameter to the [sqlite3_set_authorizer()] interface.
2302**
2303** {H12511} The second parameter to the callback is an integer
2304**          [SQLITE_COPY | action code] that specifies the particular action
2305**          to be authorized.
2306**
2307** {H12512} The third through sixth parameters to the callback are
2308**          zero-terminated strings that contain
2309**          additional details about the action to be authorized.
2310**
2311** {H12520} Each call to [sqlite3_set_authorizer()] overrides
2312**          any previously installed authorizer.
2313**
2314** {H12521} A NULL authorizer means that no authorization
2315**          callback is invoked.
2316**
2317** {H12522} The default authorizer is NULL.
2318*/
2319int sqlite3_set_authorizer(
2320  sqlite3*,
2321  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
2322  void *pUserData
2323);
2324
2325/*
2326** CAPI3REF: Authorizer Return Codes {H12590} <H12500>
2327**
2328** The [sqlite3_set_authorizer | authorizer callback function] must
2329** return either [SQLITE_OK] or one of these two constants in order
2330** to signal SQLite whether or not the action is permitted.  See the
2331** [sqlite3_set_authorizer | authorizer documentation] for additional
2332** information.
2333*/
2334#define SQLITE_DENY   1   /* Abort the SQL statement with an error */
2335#define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */
2336
2337/*
2338** CAPI3REF: Authorizer Action Codes {H12550} <H12500>
2339**
2340** The [sqlite3_set_authorizer()] interface registers a callback function
2341** that is invoked to authorize certain SQL statement actions.  The
2342** second parameter to the callback is an integer code that specifies
2343** what action is being authorized.  These are the integer action codes that
2344** the authorizer callback may be passed.
2345**
2346** These action code values signify what kind of operation is to be
2347** authorized.  The 3rd and 4th parameters to the authorization
2348** callback function will be parameters or NULL depending on which of these
2349** codes is used as the second parameter.  The 5th parameter to the
2350** authorizer callback is the name of the database ("main", "temp",
2351** etc.) if applicable.  The 6th parameter to the authorizer callback
2352** is the name of the inner-most trigger or view that is responsible for
2353** the access attempt or NULL if this access attempt is directly from
2354** top-level SQL code.
2355**
2356** INVARIANTS:
2357**
2358** {H12551} The second parameter to an
2359**          [sqlite3_set_authorizer | authorizer callback] shall be an integer
2360**          [SQLITE_COPY | authorizer code] that specifies what action
2361**          is being authorized.
2362**
2363** {H12552} The 3rd and 4th parameters to the
2364**          [sqlite3_set_authorizer | authorization callback]
2365**          shall be parameters or NULL depending on which
2366**          [SQLITE_COPY | authorizer code] is used as the second parameter.
2367**
2368** {H12553} The 5th parameter to the
2369**          [sqlite3_set_authorizer | authorizer callback] shall be the name
2370**          of the database (example: "main", "temp", etc.) if applicable.
2371**
2372** {H12554} The 6th parameter to the
2373**          [sqlite3_set_authorizer | authorizer callback] shall be the name
2374**          of the inner-most trigger or view that is responsible for
2375**          the access attempt or NULL if this access attempt is directly from
2376**          top-level SQL code.
2377*/
2378/******************************************* 3rd ************ 4th ***********/
2379#define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
2380#define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
2381#define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
2382#define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
2383#define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
2384#define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
2385#define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
2386#define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
2387#define SQLITE_DELETE                9   /* Table Name      NULL            */
2388#define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
2389#define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
2390#define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
2391#define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
2392#define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
2393#define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
2394#define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
2395#define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
2396#define SQLITE_INSERT               18   /* Table Name      NULL            */
2397#define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
2398#define SQLITE_READ                 20   /* Table Name      Column Name     */
2399#define SQLITE_SELECT               21   /* NULL            NULL            */
2400#define SQLITE_TRANSACTION          22   /* Operation       NULL            */
2401#define SQLITE_UPDATE               23   /* Table Name      Column Name     */
2402#define SQLITE_ATTACH               24   /* Filename        NULL            */
2403#define SQLITE_DETACH               25   /* Database Name   NULL            */
2404#define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
2405#define SQLITE_REINDEX              27   /* Index Name      NULL            */
2406#define SQLITE_ANALYZE              28   /* Table Name      NULL            */
2407#define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
2408#define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
2409#define SQLITE_FUNCTION             31   /* NULL            Function Name   */
2410#define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
2411#define SQLITE_COPY                  0   /* No longer used */
2412
2413/*
2414** CAPI3REF: Tracing And Profiling Functions {H12280} <S60400>
2415** EXPERIMENTAL
2416**
2417** These routines register callback functions that can be used for
2418** tracing and profiling the execution of SQL statements.
2419**
2420** The callback function registered by sqlite3_trace() is invoked at
2421** various times when an SQL statement is being run by [sqlite3_step()].
2422** The callback returns a UTF-8 rendering of the SQL statement text
2423** as the statement first begins executing.  Additional callbacks occur
2424** as each triggered subprogram is entered.  The callbacks for triggers
2425** contain a UTF-8 SQL comment that identifies the trigger.
2426**
2427** The callback function registered by sqlite3_profile() is invoked
2428** as each SQL statement finishes.  The profile callback contains
2429** the original statement text and an estimate of wall-clock time
2430** of how long that statement took to run.
2431**
2432** INVARIANTS:
2433**
2434** {H12281} The callback function registered by [sqlite3_trace()]
2435**          shall be invoked
2436**          whenever an SQL statement first begins to execute and
2437**          whenever a trigger subprogram first begins to run.
2438**
2439** {H12282} Each call to [sqlite3_trace()] shall override the previously
2440**          registered trace callback.
2441**
2442** {H12283} A NULL trace callback shall disable tracing.
2443**
2444** {H12284} The first argument to the trace callback shall be a copy of
2445**          the pointer which was the 3rd argument to [sqlite3_trace()].
2446**
2447** {H12285} The second argument to the trace callback is a
2448**          zero-terminated UTF-8 string containing the original text
2449**          of the SQL statement as it was passed into [sqlite3_prepare_v2()]
2450**          or the equivalent, or an SQL comment indicating the beginning
2451**          of a trigger subprogram.
2452**
2453** {H12287} The callback function registered by [sqlite3_profile()] is invoked
2454**          as each SQL statement finishes.
2455**
2456** {H12288} The first parameter to the profile callback is a copy of
2457**          the 3rd parameter to [sqlite3_profile()].
2458**
2459** {H12289} The second parameter to the profile callback is a
2460**          zero-terminated UTF-8 string that contains the complete text of
2461**          the SQL statement as it was processed by [sqlite3_prepare_v2()]
2462**          or the equivalent.
2463**
2464** {H12290} The third parameter to the profile callback is an estimate
2465**          of the number of nanoseconds of wall-clock time required to
2466**          run the SQL statement from start to finish.
2467*/
2468SQLITE_EXPERIMENTAL void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
2469SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
2470   void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
2471
2472/*
2473** CAPI3REF: Query Progress Callbacks {H12910} <S60400>
2474**
2475** This routine configures a callback function - the
2476** progress callback - that is invoked periodically during long
2477** running calls to [sqlite3_exec()], [sqlite3_step()] and
2478** [sqlite3_get_table()].  An example use for this
2479** interface is to keep a GUI updated during a large query.
2480**
2481** If the progress callback returns non-zero, the operation is
2482** interrupted.  This feature can be used to implement a
2483** "Cancel" button on a GUI progress dialog box.
2484**
2485** The progress handler must not do anything that will modify
2486** the database connection that invoked the progress handler.
2487** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
2488** database connections for the meaning of "modify" in this paragraph.
2489**
2490** INVARIANTS:
2491**
2492** {H12911} The callback function registered by sqlite3_progress_handler()
2493**          is invoked periodically during long running calls to
2494**          [sqlite3_step()].
2495**
2496** {H12912} The progress callback is invoked once for every N virtual
2497**          machine opcodes, where N is the second argument to
2498**          the [sqlite3_progress_handler()] call that registered
2499**          the callback.  If N is less than 1, sqlite3_progress_handler()
2500**          acts as if a NULL progress handler had been specified.
2501**
2502** {H12913} The progress callback itself is identified by the third
2503**          argument to sqlite3_progress_handler().
2504**
2505** {H12914} The fourth argument to sqlite3_progress_handler() is a
2506**          void pointer passed to the progress callback
2507**          function each time it is invoked.
2508**
2509** {H12915} If a call to [sqlite3_step()] results in fewer than N opcodes
2510**          being executed, then the progress callback is never invoked.
2511**
2512** {H12916} Every call to [sqlite3_progress_handler()]
2513**          overwrites any previously registered progress handler.
2514**
2515** {H12917} If the progress handler callback is NULL then no progress
2516**          handler is invoked.
2517**
2518** {H12918} If the progress callback returns a result other than 0, then
2519**          the behavior is a if [sqlite3_interrupt()] had been called.
2520**          <S30500>
2521*/
2522void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
2523
2524/*
2525** CAPI3REF: Opening A New Database Connection {H12700} <S40200>
2526**
2527** These routines open an SQLite database file whose name is given by the
2528** filename argument. The filename argument is interpreted as UTF-8 for
2529** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
2530** order for sqlite3_open16(). A [database connection] handle is usually
2531** returned in *ppDb, even if an error occurs.  The only exception is that
2532** if SQLite is unable to allocate memory to hold the [sqlite3] object,
2533** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
2534** object. If the database is opened (and/or created) successfully, then
2535** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.  The
2536** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
2537** an English language description of the error.
2538**
2539** The default encoding for the database will be UTF-8 if
2540** sqlite3_open() or sqlite3_open_v2() is called and
2541** UTF-16 in the native byte order if sqlite3_open16() is used.
2542**
2543** Whether or not an error occurs when it is opened, resources
2544** associated with the [database connection] handle should be released by
2545** passing it to [sqlite3_close()] when it is no longer required.
2546**
2547** The sqlite3_open_v2() interface works like sqlite3_open()
2548** except that it accepts two additional parameters for additional control
2549** over the new database connection.  The flags parameter can take one of
2550** the following three values, optionally combined with the
2551** [SQLITE_OPEN_NOMUTEX] or [SQLITE_OPEN_FULLMUTEX] flags:
2552**
2553** <dl>
2554** <dt>[SQLITE_OPEN_READONLY]</dt>
2555** <dd>The database is opened in read-only mode.  If the database does not
2556** already exist, an error is returned.</dd>
2557**
2558** <dt>[SQLITE_OPEN_READWRITE]</dt>
2559** <dd>The database is opened for reading and writing if possible, or reading
2560** only if the file is write protected by the operating system.  In either
2561** case the database must already exist, otherwise an error is returned.</dd>
2562**
2563** <dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
2564** <dd>The database is opened for reading and writing, and is creates it if
2565** it does not already exist. This is the behavior that is always used for
2566** sqlite3_open() and sqlite3_open16().</dd>
2567** </dl>
2568**
2569** If the 3rd parameter to sqlite3_open_v2() is not one of the
2570** combinations shown above or one of the combinations shown above combined
2571** with the [SQLITE_OPEN_NOMUTEX] or [SQLITE_OPEN_FULLMUTEX] flags,
2572** then the behavior is undefined.
2573**
2574** If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
2575** opens in the multi-thread [threading mode] as long as the single-thread
2576** mode has not been set at compile-time or start-time.  If the
2577** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
2578** in the serialized [threading mode] unless single-thread was
2579** previously selected at compile-time or start-time.
2580**
2581** If the filename is ":memory:", then a private, temporary in-memory database
2582** is created for the connection.  This in-memory database will vanish when
2583** the database connection is closed.  Future versions of SQLite might
2584** make use of additional special filenames that begin with the ":" character.
2585** It is recommended that when a database filename actually does begin with
2586** a ":" character you should prefix the filename with a pathname such as
2587** "./" to avoid ambiguity.
2588**
2589** If the filename is an empty string, then a private, temporary
2590** on-disk database will be created.  This private database will be
2591** automatically deleted as soon as the database connection is closed.
2592**
2593** The fourth parameter to sqlite3_open_v2() is the name of the
2594** [sqlite3_vfs] object that defines the operating system interface that
2595** the new database connection should use.  If the fourth parameter is
2596** a NULL pointer then the default [sqlite3_vfs] object is used.
2597**
2598** <b>Note to Windows users:</b>  The encoding used for the filename argument
2599** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
2600** codepage is currently defined.  Filenames containing international
2601** characters must be converted to UTF-8 prior to passing them into
2602** sqlite3_open() or sqlite3_open_v2().
2603**
2604** INVARIANTS:
2605**
2606** {H12701} The [sqlite3_open()], [sqlite3_open16()], and
2607**          [sqlite3_open_v2()] interfaces create a new
2608**          [database connection] associated with
2609**          the database file given in their first parameter.
2610**
2611** {H12702} The filename argument is interpreted as UTF-8
2612**          for [sqlite3_open()] and [sqlite3_open_v2()] and as UTF-16
2613**          in the native byte order for [sqlite3_open16()].
2614**
2615** {H12703} A successful invocation of [sqlite3_open()], [sqlite3_open16()],
2616**          or [sqlite3_open_v2()] writes a pointer to a new
2617**          [database connection] into *ppDb.
2618**
2619** {H12704} The [sqlite3_open()], [sqlite3_open16()], and
2620**          [sqlite3_open_v2()] interfaces return [SQLITE_OK] upon success,
2621**          or an appropriate [error code] on failure.
2622**
2623** {H12706} The default text encoding for a new database created using
2624**          [sqlite3_open()] or [sqlite3_open_v2()] will be UTF-8.
2625**
2626** {H12707} The default text encoding for a new database created using
2627**          [sqlite3_open16()] will be UTF-16.
2628**
2629** {H12709} The [sqlite3_open(F,D)] interface is equivalent to
2630**          [sqlite3_open_v2(F,D,G,0)] where the G parameter is
2631**          [SQLITE_OPEN_READWRITE]|[SQLITE_OPEN_CREATE].
2632**
2633** {H12711} If the G parameter to [sqlite3_open_v2(F,D,G,V)] contains the
2634**          bit value [SQLITE_OPEN_READONLY] then the database is opened
2635**          for reading only.
2636**
2637** {H12712} If the G parameter to [sqlite3_open_v2(F,D,G,V)] contains the
2638**          bit value [SQLITE_OPEN_READWRITE] then the database is opened
2639**          reading and writing if possible, or for reading only if the
2640**          file is write protected by the operating system.
2641**
2642** {H12713} If the G parameter to [sqlite3_open_v2(F,D,G,V)] omits the
2643**          bit value [SQLITE_OPEN_CREATE] and the database does not
2644**          previously exist, an error is returned.
2645**
2646** {H12714} If the G parameter to [sqlite3_open_v2(F,D,G,V)] contains the
2647**          bit value [SQLITE_OPEN_CREATE] and the database does not
2648**          previously exist, then an attempt is made to create and
2649**          initialize the database.
2650**
2651** {H12717} If the filename argument to [sqlite3_open()], [sqlite3_open16()],
2652**          or [sqlite3_open_v2()] is ":memory:", then an private,
2653**          ephemeral, in-memory database is created for the connection.
2654**          <todo>Is SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE required
2655**          in sqlite3_open_v2()?</todo>
2656**
2657** {H12719} If the filename is NULL or an empty string, then a private,
2658**          ephemeral on-disk database will be created.
2659**          <todo>Is SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE required
2660**          in sqlite3_open_v2()?</todo>
2661**
2662** {H12721} The [database connection] created by [sqlite3_open_v2(F,D,G,V)]
2663**          will use the [sqlite3_vfs] object identified by the V parameter,
2664**          or the default [sqlite3_vfs] object if V is a NULL pointer.
2665**
2666** {H12723} Two [database connections] will share a common cache if both were
2667**          opened with the same VFS while [shared cache mode] was enabled and
2668**          if both filenames compare equal using memcmp() after having been
2669**          processed by the [sqlite3_vfs | xFullPathname] method of the VFS.
2670*/
2671int sqlite3_open(
2672  const char *filename,   /* Database filename (UTF-8) */
2673  sqlite3 **ppDb          /* OUT: SQLite db handle */
2674);
2675int sqlite3_open16(
2676  const void *filename,   /* Database filename (UTF-16) */
2677  sqlite3 **ppDb          /* OUT: SQLite db handle */
2678);
2679int sqlite3_open_v2(
2680  const char *filename,   /* Database filename (UTF-8) */
2681  sqlite3 **ppDb,         /* OUT: SQLite db handle */
2682  int flags,              /* Flags */
2683  const char *zVfs        /* Name of VFS module to use */
2684);
2685
2686/*
2687** CAPI3REF: Error Codes And Messages {H12800} <S60200>
2688**
2689** The sqlite3_errcode() interface returns the numeric [result code] or
2690** [extended result code] for the most recent failed sqlite3_* API call
2691** associated with a [database connection]. If a prior API call failed
2692** but the most recent API call succeeded, the return value from
2693** sqlite3_errcode() is undefined.  The sqlite3_extended_errcode()
2694** interface is the same except that it always returns the
2695** [extended result code] even when extended result codes are
2696** disabled.
2697**
2698** The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
2699** text that describes the error, as either UTF-8 or UTF-16 respectively.
2700** Memory to hold the error message string is managed internally.
2701** The application does not need to worry about freeing the result.
2702** However, the error string might be overwritten or deallocated by
2703** subsequent calls to other SQLite interface functions.
2704**
2705** When the serialized [threading mode] is in use, it might be the
2706** case that a second error occurs on a separate thread in between
2707** the time of the first error and the call to these interfaces.
2708** When that happens, the second error will be reported since these
2709** interfaces always report the most recent result.  To avoid
2710** this, each thread can obtain exclusive use of the [database connection] D
2711** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
2712** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
2713** all calls to the interfaces listed here are completed.
2714**
2715** If an interface fails with SQLITE_MISUSE, that means the interface
2716** was invoked incorrectly by the application.  In that case, the
2717** error code and message may or may not be set.
2718**
2719** INVARIANTS:
2720**
2721** {H12801} The [sqlite3_errcode(D)] interface returns the numeric
2722**          [result code] or [extended result code] for the most recently
2723**          failed interface call associated with the [database connection] D.
2724**
2725** {H12802} The [sqlite3_extended_errcode(D)] interface returns the numeric
2726**          [extended result code] for the most recently
2727**          failed interface call associated with the [database connection] D.
2728**
2729** {H12803} The [sqlite3_errmsg(D)] and [sqlite3_errmsg16(D)]
2730**          interfaces return English-language text that describes
2731**          the error in the mostly recently failed interface call,
2732**          encoded as either UTF-8 or UTF-16 respectively.
2733**
2734** {H12807} The strings returned by [sqlite3_errmsg()] and [sqlite3_errmsg16()]
2735**          are valid until the next SQLite interface call.
2736**
2737** {H12808} Calls to API routines that do not return an error code
2738**          (example: [sqlite3_data_count()]) do not
2739**          change the error code or message returned by
2740**          [sqlite3_errcode()], [sqlite3_extended_errcode()],
2741**          [sqlite3_errmsg()], or [sqlite3_errmsg16()].
2742**
2743** {H12809} Interfaces that are not associated with a specific
2744**          [database connection] (examples:
2745**          [sqlite3_mprintf()] or [sqlite3_enable_shared_cache()]
2746**          do not change the values returned by
2747**          [sqlite3_errcode()], [sqlite3_extended_errcode()],
2748**          [sqlite3_errmsg()], or [sqlite3_errmsg16()].
2749*/
2750int sqlite3_errcode(sqlite3 *db);
2751int sqlite3_extended_errcode(sqlite3 *db);
2752const char *sqlite3_errmsg(sqlite3*);
2753const void *sqlite3_errmsg16(sqlite3*);
2754
2755/*
2756** CAPI3REF: SQL Statement Object {H13000} <H13010>
2757** KEYWORDS: {prepared statement} {prepared statements}
2758**
2759** An instance of this object represents a single SQL statement.
2760** This object is variously known as a "prepared statement" or a
2761** "compiled SQL statement" or simply as a "statement".
2762**
2763** The life of a statement object goes something like this:
2764**
2765** <ol>
2766** <li> Create the object using [sqlite3_prepare_v2()] or a related
2767**      function.
2768** <li> Bind values to [host parameters] using the sqlite3_bind_*()
2769**      interfaces.
2770** <li> Run the SQL by calling [sqlite3_step()] one or more times.
2771** <li> Reset the statement using [sqlite3_reset()] then go back
2772**      to step 2.  Do this zero or more times.
2773** <li> Destroy the object using [sqlite3_finalize()].
2774** </ol>
2775**
2776** Refer to documentation on individual methods above for additional
2777** information.
2778*/
2779typedef struct sqlite3_stmt sqlite3_stmt;
2780
2781/*
2782** CAPI3REF: Run-time Limits {H12760} <S20600>
2783**
2784** This interface allows the size of various constructs to be limited
2785** on a connection by connection basis.  The first parameter is the
2786** [database connection] whose limit is to be set or queried.  The
2787** second parameter is one of the [limit categories] that define a
2788** class of constructs to be size limited.  The third parameter is the
2789** new limit for that construct.  The function returns the old limit.
2790**
2791** If the new limit is a negative number, the limit is unchanged.
2792** For the limit category of SQLITE_LIMIT_XYZ there is a hard upper
2793** bound set by a compile-time C preprocessor macro named SQLITE_MAX_XYZ.
2794** (The "_LIMIT_" in the name is changed to "_MAX_".)
2795** Attempts to increase a limit above its hard upper bound are
2796** silently truncated to the hard upper limit.
2797**
2798** Run time limits are intended for use in applications that manage
2799** both their own internal database and also databases that are controlled
2800** by untrusted external sources.  An example application might be a
2801** webbrowser that has its own databases for storing history and
2802** separate databases controlled by JavaScript applications downloaded
2803** off the Internet.  The internal databases can be given the
2804** large, default limits.  Databases managed by external sources can
2805** be given much smaller limits designed to prevent a denial of service
2806** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
2807** interface to further control untrusted SQL.  The size of the database
2808** created by an untrusted script can be contained using the
2809** [max_page_count] [PRAGMA].
2810**
2811** New run-time limit categories may be added in future releases.
2812**
2813** INVARIANTS:
2814**
2815** {H12762} A successful call to [sqlite3_limit(D,C,V)] where V is
2816**          positive changes the limit on the size of construct C in the
2817**          [database connection] D to the lesser of V and the hard upper
2818**          bound on the size of C that is set at compile-time.
2819**
2820** {H12766} A successful call to [sqlite3_limit(D,C,V)] where V is negative
2821**          leaves the state of the [database connection] D unchanged.
2822**
2823** {H12769} A successful call to [sqlite3_limit(D,C,V)] returns the
2824**          value of the limit on the size of construct C in the
2825**          [database connection] D as it was prior to the call.
2826*/
2827int sqlite3_limit(sqlite3*, int id, int newVal);
2828
2829/*
2830** CAPI3REF: Run-Time Limit Categories {H12790} <H12760>
2831** KEYWORDS: {limit category} {limit categories}
2832**
2833** These constants define various aspects of a [database connection]
2834** that can be limited in size by calls to [sqlite3_limit()].
2835** The meanings of the various limits are as follows:
2836**
2837** <dl>
2838** <dt>SQLITE_LIMIT_LENGTH</dt>
2839** <dd>The maximum size of any string or BLOB or table row.<dd>
2840**
2841** <dt>SQLITE_LIMIT_SQL_LENGTH</dt>
2842** <dd>The maximum length of an SQL statement.</dd>
2843**
2844** <dt>SQLITE_LIMIT_COLUMN</dt>
2845** <dd>The maximum number of columns in a table definition or in the
2846** result set of a SELECT or the maximum number of columns in an index
2847** or in an ORDER BY or GROUP BY clause.</dd>
2848**
2849** <dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
2850** <dd>The maximum depth of the parse tree on any expression.</dd>
2851**
2852** <dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
2853** <dd>The maximum number of terms in a compound SELECT statement.</dd>
2854**
2855** <dt>SQLITE_LIMIT_VDBE_OP</dt>
2856** <dd>The maximum number of instructions in a virtual machine program
2857** used to implement an SQL statement.</dd>
2858**
2859** <dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
2860** <dd>The maximum number of arguments on a function.</dd>
2861**
2862** <dt>SQLITE_LIMIT_ATTACHED</dt>
2863** <dd>The maximum number of attached databases.</dd>
2864**
2865** <dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
2866** <dd>The maximum length of the pattern argument to the LIKE or
2867** GLOB operators.</dd>
2868**
2869** <dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
2870** <dd>The maximum number of variables in an SQL statement that can
2871** be bound.</dd>
2872** </dl>
2873*/
2874#define SQLITE_LIMIT_LENGTH                    0
2875#define SQLITE_LIMIT_SQL_LENGTH                1
2876#define SQLITE_LIMIT_COLUMN                    2
2877#define SQLITE_LIMIT_EXPR_DEPTH                3
2878#define SQLITE_LIMIT_COMPOUND_SELECT           4
2879#define SQLITE_LIMIT_VDBE_OP                   5
2880#define SQLITE_LIMIT_FUNCTION_ARG              6
2881#define SQLITE_LIMIT_ATTACHED                  7
2882#define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
2883#define SQLITE_LIMIT_VARIABLE_NUMBER           9
2884
2885/*
2886** CAPI3REF: Compiling An SQL Statement {H13010} <S10000>
2887** KEYWORDS: {SQL statement compiler}
2888**
2889** To execute an SQL query, it must first be compiled into a byte-code
2890** program using one of these routines.
2891**
2892** The first argument, "db", is a [database connection] obtained from a
2893** prior call to [sqlite3_open()], [sqlite3_open_v2()] or [sqlite3_open16()].
2894**
2895** The second argument, "zSql", is the statement to be compiled, encoded
2896** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
2897** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
2898** use UTF-16.
2899**
2900** If the nByte argument is less than zero, then zSql is read up to the
2901** first zero terminator. If nByte is non-negative, then it is the maximum
2902** number of  bytes read from zSql.  When nByte is non-negative, the
2903** zSql string ends at either the first '\000' or '\u0000' character or
2904** the nByte-th byte, whichever comes first. If the caller knows
2905** that the supplied string is nul-terminated, then there is a small
2906** performance advantage to be gained by passing an nByte parameter that
2907** is equal to the number of bytes in the input string <i>including</i>
2908** the nul-terminator bytes.
2909**
2910** *pzTail is made to point to the first byte past the end of the
2911** first SQL statement in zSql.  These routines only compile the first
2912** statement in zSql, so *pzTail is left pointing to what remains
2913** uncompiled.
2914**
2915** *ppStmt is left pointing to a compiled [prepared statement] that can be
2916** executed using [sqlite3_step()].  If there is an error, *ppStmt is set
2917** to NULL.  If the input text contains no SQL (if the input is an empty
2918** string or a comment) then *ppStmt is set to NULL.
2919** {A13018} The calling procedure is responsible for deleting the compiled
2920** SQL statement using [sqlite3_finalize()] after it has finished with it.
2921**
2922** On success, [SQLITE_OK] is returned, otherwise an [error code] is returned.
2923**
2924** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
2925** recommended for all new programs. The two older interfaces are retained
2926** for backwards compatibility, but their use is discouraged.
2927** In the "v2" interfaces, the prepared statement
2928** that is returned (the [sqlite3_stmt] object) contains a copy of the
2929** original SQL text. This causes the [sqlite3_step()] interface to
2930** behave a differently in two ways:
2931**
2932** <ol>
2933** <li>
2934** If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
2935** always used to do, [sqlite3_step()] will automatically recompile the SQL
2936** statement and try to run it again.  If the schema has changed in
2937** a way that makes the statement no longer valid, [sqlite3_step()] will still
2938** return [SQLITE_SCHEMA].  But unlike the legacy behavior, [SQLITE_SCHEMA] is
2939** now a fatal error.  Calling [sqlite3_prepare_v2()] again will not make the
2940** error go away.  Note: use [sqlite3_errmsg()] to find the text
2941** of the parsing error that results in an [SQLITE_SCHEMA] return.
2942** </li>
2943**
2944** <li>
2945** When an error occurs, [sqlite3_step()] will return one of the detailed
2946** [error codes] or [extended error codes].  The legacy behavior was that
2947** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
2948** and you would have to make a second call to [sqlite3_reset()] in order
2949** to find the underlying cause of the problem. With the "v2" prepare
2950** interfaces, the underlying reason for the error is returned immediately.
2951** </li>
2952** </ol>
2953**
2954** INVARIANTS:
2955**
2956** {H13011} The [sqlite3_prepare(db,zSql,...)] and
2957**          [sqlite3_prepare_v2(db,zSql,...)] interfaces interpret the
2958**          text in their zSql parameter as UTF-8.
2959**
2960** {H13012} The [sqlite3_prepare16(db,zSql,...)] and
2961**          [sqlite3_prepare16_v2(db,zSql,...)] interfaces interpret the
2962**          text in their zSql parameter as UTF-16 in the native byte order.
2963**
2964** {H13013} If the nByte argument to [sqlite3_prepare_v2(db,zSql,nByte,...)]
2965**          and its variants is less than zero, the SQL text is
2966**          read from zSql is read up to the first zero terminator.
2967**
2968** {H13014} If the nByte argument to [sqlite3_prepare_v2(db,zSql,nByte,...)]
2969**          and its variants is non-negative, then at most nBytes bytes of
2970**          SQL text is read from zSql.
2971**
2972** {H13015} In [sqlite3_prepare_v2(db,zSql,N,P,pzTail)] and its variants
2973**          if the zSql input text contains more than one SQL statement
2974**          and pzTail is not NULL, then *pzTail is made to point to the
2975**          first byte past the end of the first SQL statement in zSql.
2976**          <todo>What does *pzTail point to if there is one statement?</todo>
2977**
2978** {H13016} A successful call to [sqlite3_prepare_v2(db,zSql,N,ppStmt,...)]
2979**          or one of its variants writes into *ppStmt a pointer to a new
2980**          [prepared statement] or a pointer to NULL if zSql contains
2981**          nothing other than whitespace or comments.
2982**
2983** {H13019} The [sqlite3_prepare_v2()] interface and its variants return
2984**          [SQLITE_OK] or an appropriate [error code] upon failure.
2985**
2986** {H13021} Before [sqlite3_prepare(db,zSql,nByte,ppStmt,pzTail)] or its
2987**          variants returns an error (any value other than [SQLITE_OK]),
2988**          they first set *ppStmt to NULL.
2989*/
2990int sqlite3_prepare(
2991  sqlite3 *db,            /* Database handle */
2992  const char *zSql,       /* SQL statement, UTF-8 encoded */
2993  int nByte,              /* Maximum length of zSql in bytes. */
2994  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
2995  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
2996);
2997int sqlite3_prepare_v2(
2998  sqlite3 *db,            /* Database handle */
2999  const char *zSql,       /* SQL statement, UTF-8 encoded */
3000  int nByte,              /* Maximum length of zSql in bytes. */
3001  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
3002  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
3003);
3004int sqlite3_prepare16(
3005  sqlite3 *db,            /* Database handle */
3006  const void *zSql,       /* SQL statement, UTF-16 encoded */
3007  int nByte,              /* Maximum length of zSql in bytes. */
3008  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
3009  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
3010);
3011int sqlite3_prepare16_v2(
3012  sqlite3 *db,            /* Database handle */
3013  const void *zSql,       /* SQL statement, UTF-16 encoded */
3014  int nByte,              /* Maximum length of zSql in bytes. */
3015  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
3016  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
3017);
3018
3019/*
3020** CAPI3REF: Retrieving Statement SQL {H13100} <H13000>
3021**
3022** This interface can be used to retrieve a saved copy of the original
3023** SQL text used to create a [prepared statement] if that statement was
3024** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
3025**
3026** INVARIANTS:
3027**
3028** {H13101} If the [prepared statement] passed as the argument to
3029**          [sqlite3_sql()] was compiled using either [sqlite3_prepare_v2()] or
3030**          [sqlite3_prepare16_v2()], then [sqlite3_sql()] returns
3031**          a pointer to a zero-terminated string containing a UTF-8 rendering
3032**          of the original SQL statement.
3033**
3034** {H13102} If the [prepared statement] passed as the argument to
3035**          [sqlite3_sql()] was compiled using either [sqlite3_prepare()] or
3036**          [sqlite3_prepare16()], then [sqlite3_sql()] returns a NULL pointer.
3037**
3038** {H13103} The string returned by [sqlite3_sql(S)] is valid until the
3039**          [prepared statement] S is deleted using [sqlite3_finalize(S)].
3040*/
3041const char *sqlite3_sql(sqlite3_stmt *pStmt);
3042
3043/*
3044** CAPI3REF: Dynamically Typed Value Object {H15000} <S20200>
3045** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
3046**
3047** SQLite uses the sqlite3_value object to represent all values
3048** that can be stored in a database table. SQLite uses dynamic typing
3049** for the values it stores. Values stored in sqlite3_value objects
3050** can be integers, floating point values, strings, BLOBs, or NULL.
3051**
3052** An sqlite3_value object may be either "protected" or "unprotected".
3053** Some interfaces require a protected sqlite3_value.  Other interfaces
3054** will accept either a protected or an unprotected sqlite3_value.
3055** Every interface that accepts sqlite3_value arguments specifies
3056** whether or not it requires a protected sqlite3_value.
3057**
3058** The terms "protected" and "unprotected" refer to whether or not
3059** a mutex is held.  A internal mutex is held for a protected
3060** sqlite3_value object but no mutex is held for an unprotected
3061** sqlite3_value object.  If SQLite is compiled to be single-threaded
3062** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
3063** or if SQLite is run in one of reduced mutex modes
3064** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
3065** then there is no distinction between protected and unprotected
3066** sqlite3_value objects and they can be used interchangeably.  However,
3067** for maximum code portability it is recommended that applications
3068** still make the distinction between between protected and unprotected
3069** sqlite3_value objects even when not strictly required.
3070**
3071** The sqlite3_value objects that are passed as parameters into the
3072** implementation of [application-defined SQL functions] are protected.
3073** The sqlite3_value object returned by
3074** [sqlite3_column_value()] is unprotected.
3075** Unprotected sqlite3_value objects may only be used with
3076** [sqlite3_result_value()] and [sqlite3_bind_value()].
3077** The [sqlite3_value_blob | sqlite3_value_type()] family of
3078** interfaces require protected sqlite3_value objects.
3079*/
3080typedef struct Mem sqlite3_value;
3081
3082/*
3083** CAPI3REF: SQL Function Context Object {H16001} <S20200>
3084**
3085** The context in which an SQL function executes is stored in an
3086** sqlite3_context object.  A pointer to an sqlite3_context object
3087** is always first parameter to [application-defined SQL functions].
3088** The application-defined SQL function implementation will pass this
3089** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
3090** [sqlite3_aggregate_context()], [sqlite3_user_data()],
3091** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
3092** and/or [sqlite3_set_auxdata()].
3093*/
3094typedef struct sqlite3_context sqlite3_context;
3095
3096/*
3097** CAPI3REF: Binding Values To Prepared Statements {H13500} <S70300>
3098** KEYWORDS: {host parameter} {host parameters} {host parameter name}
3099** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
3100**
3101** In the SQL strings input to [sqlite3_prepare_v2()] and its variants,
3102** literals may be replaced by a parameter in one of these forms:
3103**
3104** <ul>
3105** <li>  ?
3106** <li>  ?NNN
3107** <li>  :VVV
3108** <li>  @VVV
3109** <li>  $VVV
3110** </ul>
3111**
3112** In the parameter forms shown above NNN is an integer literal,
3113** and VVV is an alpha-numeric parameter name. The values of these
3114** parameters (also called "host parameter names" or "SQL parameters")
3115** can be set using the sqlite3_bind_*() routines defined here.
3116**
3117** The first argument to the sqlite3_bind_*() routines is always
3118** a pointer to the [sqlite3_stmt] object returned from
3119** [sqlite3_prepare_v2()] or its variants.
3120**
3121** The second argument is the index of the SQL parameter to be set.
3122** The leftmost SQL parameter has an index of 1.  When the same named
3123** SQL parameter is used more than once, second and subsequent
3124** occurrences have the same index as the first occurrence.
3125** The index for named parameters can be looked up using the
3126** [sqlite3_bind_parameter_index()] API if desired.  The index
3127** for "?NNN" parameters is the value of NNN.
3128** The NNN value must be between 1 and the [sqlite3_limit()]
3129** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
3130**
3131** The third argument is the value to bind to the parameter.
3132**
3133** In those routines that have a fourth argument, its value is the
3134** number of bytes in the parameter.  To be clear: the value is the
3135** number of <u>bytes</u> in the value, not the number of characters.
3136** If the fourth parameter is negative, the length of the string is
3137** the number of bytes up to the first zero terminator.
3138**
3139** The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
3140** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
3141** string after SQLite has finished with it. If the fifth argument is
3142** the special value [SQLITE_STATIC], then SQLite assumes that the
3143** information is in static, unmanaged space and does not need to be freed.
3144** If the fifth argument has the value [SQLITE_TRANSIENT], then
3145** SQLite makes its own private copy of the data immediately, before
3146** the sqlite3_bind_*() routine returns.
3147**
3148** The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
3149** is filled with zeroes.  A zeroblob uses a fixed amount of memory
3150** (just an integer to hold its size) while it is being processed.
3151** Zeroblobs are intended to serve as placeholders for BLOBs whose
3152** content is later written using
3153** [sqlite3_blob_open | incremental BLOB I/O] routines.
3154** A negative value for the zeroblob results in a zero-length BLOB.
3155**
3156** The sqlite3_bind_*() routines must be called after
3157** [sqlite3_prepare_v2()] (and its variants) or [sqlite3_reset()] and
3158** before [sqlite3_step()].
3159** Bindings are not cleared by the [sqlite3_reset()] routine.
3160** Unbound parameters are interpreted as NULL.
3161**
3162** These routines return [SQLITE_OK] on success or an error code if
3163** anything goes wrong.  [SQLITE_RANGE] is returned if the parameter
3164** index is out of range.  [SQLITE_NOMEM] is returned if malloc() fails.
3165** [SQLITE_MISUSE] might be returned if these routines are called on a
3166** virtual machine that is the wrong state or which has already been finalized.
3167** Detection of misuse is unreliable.  Applications should not depend
3168** on SQLITE_MISUSE returns.  SQLITE_MISUSE is intended to indicate a
3169** a logic error in the application.  Future versions of SQLite might
3170** panic rather than return SQLITE_MISUSE.
3171**
3172** See also: [sqlite3_bind_parameter_count()],
3173** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
3174**
3175** INVARIANTS:
3176**
3177** {H13506} The [SQL statement compiler] recognizes tokens of the forms
3178**          "?", "?NNN", "$VVV", ":VVV", and "@VVV" as SQL parameters,
3179**          where NNN is any sequence of one or more digits
3180**          and where VVV is any sequence of one or more alphanumeric
3181**          characters or "::" optionally followed by a string containing
3182**          no spaces and contained within parentheses.
3183**
3184** {H13509} The initial value of an SQL parameter is NULL.
3185**
3186** {H13512} The index of an "?" SQL parameter is one larger than the
3187**          largest index of SQL parameter to the left, or 1 if
3188**          the "?" is the leftmost SQL parameter.
3189**
3190** {H13515} The index of an "?NNN" SQL parameter is the integer NNN.
3191**
3192** {H13518} The index of an ":VVV", "$VVV", or "@VVV" SQL parameter is
3193**          the same as the index of leftmost occurrences of the same
3194**          parameter, or one more than the largest index over all
3195**          parameters to the left if this is the first occurrence
3196**          of this parameter, or 1 if this is the leftmost parameter.
3197**
3198** {H13521} The [SQL statement compiler] fails with an [SQLITE_RANGE]
3199**          error if the index of an SQL parameter is less than 1
3200**          or greater than the compile-time SQLITE_MAX_VARIABLE_NUMBER
3201**          parameter.
3202**
3203** {H13524} Calls to [sqlite3_bind_text | sqlite3_bind(S,N,V,...)]
3204**          associate the value V with all SQL parameters having an
3205**          index of N in the [prepared statement] S.
3206**
3207** {H13527} Calls to [sqlite3_bind_text | sqlite3_bind(S,N,...)]
3208**          override prior calls with the same values of S and N.
3209**
3210** {H13530} Bindings established by [sqlite3_bind_text | sqlite3_bind(S,...)]
3211**          persist across calls to [sqlite3_reset(S)].
3212**
3213** {H13533} In calls to [sqlite3_bind_blob(S,N,V,L,D)],
3214**          [sqlite3_bind_text(S,N,V,L,D)], or
3215**          [sqlite3_bind_text16(S,N,V,L,D)] SQLite binds the first L
3216**          bytes of the BLOB or string pointed to by V, when L
3217**          is non-negative.
3218**
3219** {H13536} In calls to [sqlite3_bind_text(S,N,V,L,D)] or
3220**          [sqlite3_bind_text16(S,N,V,L,D)] SQLite binds characters
3221**          from V through the first zero character when L is negative.
3222**
3223** {H13539} In calls to [sqlite3_bind_blob(S,N,V,L,D)],
3224**          [sqlite3_bind_text(S,N,V,L,D)], or
3225**          [sqlite3_bind_text16(S,N,V,L,D)] when D is the special
3226**          constant [SQLITE_STATIC], SQLite assumes that the value V
3227**          is held in static unmanaged space that will not change
3228**          during the lifetime of the binding.
3229**
3230** {H13542} In calls to [sqlite3_bind_blob(S,N,V,L,D)],
3231**          [sqlite3_bind_text(S,N,V,L,D)], or
3232**          [sqlite3_bind_text16(S,N,V,L,D)] when D is the special
3233**          constant [SQLITE_TRANSIENT], the routine makes a
3234**          private copy of the value V before it returns.
3235**
3236** {H13545} In calls to [sqlite3_bind_blob(S,N,V,L,D)],
3237**          [sqlite3_bind_text(S,N,V,L,D)], or
3238**          [sqlite3_bind_text16(S,N,V,L,D)] when D is a pointer to
3239**          a function, SQLite invokes that function to destroy the
3240**          value V after it has finished using the value V.
3241**
3242** {H13548} In calls to [sqlite3_bind_zeroblob(S,N,V,L)] the value bound
3243**          is a BLOB of L bytes, or a zero-length BLOB if L is negative.
3244**
3245** {H13551} In calls to [sqlite3_bind_value(S,N,V)] the V argument may
3246**          be either a [protected sqlite3_value] object or an
3247**          [unprotected sqlite3_value] object.
3248*/
3249int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
3250int sqlite3_bind_double(sqlite3_stmt*, int, double);
3251int sqlite3_bind_int(sqlite3_stmt*, int, int);
3252int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
3253int sqlite3_bind_null(sqlite3_stmt*, int);
3254int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*));
3255int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
3256int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
3257int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
3258
3259/*
3260** CAPI3REF: Number Of SQL Parameters {H13600} <S70300>
3261**
3262** This routine can be used to find the number of [SQL parameters]
3263** in a [prepared statement].  SQL parameters are tokens of the
3264** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
3265** placeholders for values that are [sqlite3_bind_blob | bound]
3266** to the parameters at a later time.
3267**
3268** This routine actually returns the index of the largest (rightmost)
3269** parameter. For all forms except ?NNN, this will correspond to the
3270** number of unique parameters.  If parameters of the ?NNN are used,
3271** there may be gaps in the list.
3272**
3273** See also: [sqlite3_bind_blob|sqlite3_bind()],
3274** [sqlite3_bind_parameter_name()], and
3275** [sqlite3_bind_parameter_index()].
3276**
3277** INVARIANTS:
3278**
3279** {H13601} The [sqlite3_bind_parameter_count(S)] interface returns
3280**          the largest index of all SQL parameters in the
3281**          [prepared statement] S, or 0 if S contains no SQL parameters.
3282*/
3283int sqlite3_bind_parameter_count(sqlite3_stmt*);
3284
3285/*
3286** CAPI3REF: Name Of A Host Parameter {H13620} <S70300>
3287**
3288** This routine returns a pointer to the name of the n-th
3289** [SQL parameter] in a [prepared statement].
3290** SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
3291** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
3292** respectively.
3293** In other words, the initial ":" or "$" or "@" or "?"
3294** is included as part of the name.
3295** Parameters of the form "?" without a following integer have no name
3296** and are also referred to as "anonymous parameters".
3297**
3298** The first host parameter has an index of 1, not 0.
3299**
3300** If the value n is out of range or if the n-th parameter is
3301** nameless, then NULL is returned.  The returned string is
3302** always in UTF-8 encoding even if the named parameter was
3303** originally specified as UTF-16 in [sqlite3_prepare16()] or
3304** [sqlite3_prepare16_v2()].
3305**
3306** See also: [sqlite3_bind_blob|sqlite3_bind()],
3307** [sqlite3_bind_parameter_count()], and
3308** [sqlite3_bind_parameter_index()].
3309**
3310** INVARIANTS:
3311**
3312** {H13621} The [sqlite3_bind_parameter_name(S,N)] interface returns
3313**          a UTF-8 rendering of the name of the SQL parameter in
3314**          the [prepared statement] S having index N, or
3315**          NULL if there is no SQL parameter with index N or if the
3316**          parameter with index N is an anonymous parameter "?".
3317*/
3318const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);
3319
3320/*
3321** CAPI3REF: Index Of A Parameter With A Given Name {H13640} <S70300>
3322**
3323** Return the index of an SQL parameter given its name.  The
3324** index value returned is suitable for use as the second
3325** parameter to [sqlite3_bind_blob|sqlite3_bind()].  A zero
3326** is returned if no matching parameter is found.  The parameter
3327** name must be given in UTF-8 even if the original statement
3328** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
3329**
3330** See also: [sqlite3_bind_blob|sqlite3_bind()],
3331** [sqlite3_bind_parameter_count()], and
3332** [sqlite3_bind_parameter_index()].
3333**
3334** INVARIANTS:
3335**
3336** {H13641} The [sqlite3_bind_parameter_index(S,N)] interface returns
3337**          the index of SQL parameter in the [prepared statement]
3338**          S whose name matches the UTF-8 string N, or 0 if there is
3339**          no match.
3340*/
3341int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
3342
3343/*
3344** CAPI3REF: Reset All Bindings On A Prepared Statement {H13660} <S70300>
3345**
3346** Contrary to the intuition of many, [sqlite3_reset()] does not reset
3347** the [sqlite3_bind_blob | bindings] on a [prepared statement].
3348** Use this routine to reset all host parameters to NULL.
3349**
3350** INVARIANTS:
3351**
3352** {H13661} The [sqlite3_clear_bindings(S)] interface resets all SQL
3353**          parameter bindings in the [prepared statement] S back to NULL.
3354*/
3355int sqlite3_clear_bindings(sqlite3_stmt*);
3356
3357/*
3358** CAPI3REF: Number Of Columns In A Result Set {H13710} <S10700>
3359**
3360** Return the number of columns in the result set returned by the
3361** [prepared statement]. This routine returns 0 if pStmt is an SQL
3362** statement that does not return data (for example an [UPDATE]).
3363**
3364** INVARIANTS:
3365**
3366** {H13711} The [sqlite3_column_count(S)] interface returns the number of
3367**          columns in the result set generated by the [prepared statement] S,
3368**          or 0 if S does not generate a result set.
3369*/
3370int sqlite3_column_count(sqlite3_stmt *pStmt);
3371
3372/*
3373** CAPI3REF: Column Names In A Result Set {H13720} <S10700>
3374**
3375** These routines return the name assigned to a particular column
3376** in the result set of a [SELECT] statement.  The sqlite3_column_name()
3377** interface returns a pointer to a zero-terminated UTF-8 string
3378** and sqlite3_column_name16() returns a pointer to a zero-terminated
3379** UTF-16 string.  The first parameter is the [prepared statement]
3380** that implements the [SELECT] statement. The second parameter is the
3381** column number.  The leftmost column is number 0.
3382**
3383** The returned string pointer is valid until either the [prepared statement]
3384** is destroyed by [sqlite3_finalize()] or until the next call to
3385** sqlite3_column_name() or sqlite3_column_name16() on the same column.
3386**
3387** If sqlite3_malloc() fails during the processing of either routine
3388** (for example during a conversion from UTF-8 to UTF-16) then a
3389** NULL pointer is returned.
3390**
3391** The name of a result column is the value of the "AS" clause for
3392** that column, if there is an AS clause.  If there is no AS clause
3393** then the name of the column is unspecified and may change from
3394** one release of SQLite to the next.
3395**
3396** INVARIANTS:
3397**
3398** {H13721} A successful invocation of the [sqlite3_column_name(S,N)]
3399**          interface returns the name of the Nth column (where 0 is
3400**          the leftmost column) for the result set of the
3401**          [prepared statement] S as a zero-terminated UTF-8 string.
3402**
3403** {H13723} A successful invocation of the [sqlite3_column_name16(S,N)]
3404**          interface returns the name of the Nth column (where 0 is
3405**          the leftmost column) for the result set of the
3406**          [prepared statement] S as a zero-terminated UTF-16 string
3407**          in the native byte order.
3408**
3409** {H13724} The [sqlite3_column_name()] and [sqlite3_column_name16()]
3410**          interfaces return a NULL pointer if they are unable to
3411**          allocate memory to hold their normal return strings.
3412**
3413** {H13725} If the N parameter to [sqlite3_column_name(S,N)] or
3414**          [sqlite3_column_name16(S,N)] is out of range, then the
3415**          interfaces return a NULL pointer.
3416**
3417** {H13726} The strings returned by [sqlite3_column_name(S,N)] and
3418**          [sqlite3_column_name16(S,N)] are valid until the next
3419**          call to either routine with the same S and N parameters
3420**          or until [sqlite3_finalize(S)] is called.
3421**
3422** {H13727} When a result column of a [SELECT] statement contains
3423**          an AS clause, the name of that column is the identifier
3424**          to the right of the AS keyword.
3425*/
3426const char *sqlite3_column_name(sqlite3_stmt*, int N);
3427const void *sqlite3_column_name16(sqlite3_stmt*, int N);
3428
3429/*
3430** CAPI3REF: Source Of Data In A Query Result {H13740} <S10700>
3431**
3432** These routines provide a means to determine what column of what
3433** table in which database a result of a [SELECT] statement comes from.
3434** The name of the database or table or column can be returned as
3435** either a UTF-8 or UTF-16 string.  The _database_ routines return
3436** the database name, the _table_ routines return the table name, and
3437** the origin_ routines return the column name.
3438** The returned string is valid until the [prepared statement] is destroyed
3439** using [sqlite3_finalize()] or until the same information is requested
3440** again in a different encoding.
3441**
3442** The names returned are the original un-aliased names of the
3443** database, table, and column.
3444**
3445** The first argument to the following calls is a [prepared statement].
3446** These functions return information about the Nth column returned by
3447** the statement, where N is the second function argument.
3448**
3449** If the Nth column returned by the statement is an expression or
3450** subquery and is not a column value, then all of these functions return
3451** NULL.  These routine might also return NULL if a memory allocation error
3452** occurs.  Otherwise, they return the name of the attached database, table
3453** and column that query result column was extracted from.
3454**
3455** As with all other SQLite APIs, those postfixed with "16" return
3456** UTF-16 encoded strings, the other functions return UTF-8. {END}
3457**
3458** These APIs are only available if the library was compiled with the
3459** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
3460**
3461** {A13751}
3462** If two or more threads call one or more of these routines against the same
3463** prepared statement and column at the same time then the results are
3464** undefined.
3465**
3466** INVARIANTS:
3467**
3468** {H13741} The [sqlite3_column_database_name(S,N)] interface returns either
3469**          the UTF-8 zero-terminated name of the database from which the
3470**          Nth result column of the [prepared statement] S is extracted,
3471**          or NULL if the Nth column of S is a general expression
3472**          or if unable to allocate memory to store the name.
3473**
3474** {H13742} The [sqlite3_column_database_name16(S,N)] interface returns either
3475**          the UTF-16 native byte order zero-terminated name of the database
3476**          from which the Nth result column of the [prepared statement] S is
3477**          extracted, or NULL if the Nth column of S is a general expression
3478**          or if unable to allocate memory to store the name.
3479**
3480** {H13743} The [sqlite3_column_table_name(S,N)] interface returns either
3481**          the UTF-8 zero-terminated name of the table from which the
3482**          Nth result column of the [prepared statement] S is extracted,
3483**          or NULL if the Nth column of S is a general expression
3484**          or if unable to allocate memory to store the name.
3485**
3486** {H13744} The [sqlite3_column_table_name16(S,N)] interface returns either
3487**          the UTF-16 native byte order zero-terminated name of the table
3488**          from which the Nth result column of the [prepared statement] S is
3489**          extracted, or NULL if the Nth column of S is a general expression
3490**          or if unable to allocate memory to store the name.
3491**
3492** {H13745} The [sqlite3_column_origin_name(S,N)] interface returns either
3493**          the UTF-8 zero-terminated name of the table column from which the
3494**          Nth result column of the [prepared statement] S is extracted,
3495**          or NULL if the Nth column of S is a general expression
3496**          or if unable to allocate memory to store the name.
3497**
3498** {H13746} The [sqlite3_column_origin_name16(S,N)] interface returns either
3499**          the UTF-16 native byte order zero-terminated name of the table
3500**          column from which the Nth result column of the
3501**          [prepared statement] S is extracted, or NULL if the Nth column
3502**          of S is a general expression or if unable to allocate memory
3503**          to store the name.
3504**
3505** {H13748} The return values from
3506**          [sqlite3_column_database_name | column metadata interfaces]
3507**          are valid for the lifetime of the [prepared statement]
3508**          or until the encoding is changed by another metadata
3509**          interface call for the same prepared statement and column.
3510**
3511** ASSUMPTIONS:
3512**
3513** {A13751} If two or more threads call one or more
3514**          [sqlite3_column_database_name | column metadata interfaces]
3515**          for the same [prepared statement] and result column
3516**          at the same time then the results are undefined.
3517*/
3518const char *sqlite3_column_database_name(sqlite3_stmt*,int);
3519const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
3520const char *sqlite3_column_table_name(sqlite3_stmt*,int);
3521const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
3522const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
3523const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);
3524
3525/*
3526** CAPI3REF: Declared Datatype Of A Query Result {H13760} <S10700>
3527**
3528** The first parameter is a [prepared statement].
3529** If this statement is a [SELECT] statement and the Nth column of the
3530** returned result set of that [SELECT] is a table column (not an
3531** expression or subquery) then the declared type of the table
3532** column is returned.  If the Nth column of the result set is an
3533** expression or subquery, then a NULL pointer is returned.
3534** The returned string is always UTF-8 encoded. {END}
3535**
3536** For example, given the database schema:
3537**
3538** CREATE TABLE t1(c1 VARIANT);
3539**
3540** and the following statement to be compiled:
3541**
3542** SELECT c1 + 1, c1 FROM t1;
3543**
3544** this routine would return the string "VARIANT" for the second result
3545** column (i==1), and a NULL pointer for the first result column (i==0).
3546**
3547** SQLite uses dynamic run-time typing.  So just because a column
3548** is declared to contain a particular type does not mean that the
3549** data stored in that column is of the declared type.  SQLite is
3550** strongly typed, but the typing is dynamic not static.  Type
3551** is associated with individual values, not with the containers
3552** used to hold those values.
3553**
3554** INVARIANTS:
3555**
3556** {H13761}  A successful call to [sqlite3_column_decltype(S,N)] returns a
3557**           zero-terminated UTF-8 string containing the declared datatype
3558**           of the table column that appears as the Nth column (numbered
3559**           from 0) of the result set to the [prepared statement] S.
3560**
3561** {H13762}  A successful call to [sqlite3_column_decltype16(S,N)]
3562**           returns a zero-terminated UTF-16 native byte order string
3563**           containing the declared datatype of the table column that appears
3564**           as the Nth column (numbered from 0) of the result set to the
3565**           [prepared statement] S.
3566**
3567** {H13763}  If N is less than 0 or N is greater than or equal to
3568**           the number of columns in the [prepared statement] S,
3569**           or if the Nth column of S is an expression or subquery rather
3570**           than a table column, or if a memory allocation failure
3571**           occurs during encoding conversions, then
3572**           calls to [sqlite3_column_decltype(S,N)] or
3573**           [sqlite3_column_decltype16(S,N)] return NULL.
3574*/
3575const char *sqlite3_column_decltype(sqlite3_stmt*,int);
3576const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
3577
3578/*
3579** CAPI3REF: Evaluate An SQL Statement {H13200} <S10000>
3580**
3581** After a [prepared statement] has been prepared using either
3582** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
3583** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
3584** must be called one or more times to evaluate the statement.
3585**
3586** The details of the behavior of the sqlite3_step() interface depend
3587** on whether the statement was prepared using the newer "v2" interface
3588** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
3589** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
3590** new "v2" interface is recommended for new applications but the legacy
3591** interface will continue to be supported.
3592**
3593** In the legacy interface, the return value will be either [SQLITE_BUSY],
3594** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
3595** With the "v2" interface, any of the other [result codes] or
3596** [extended result codes] might be returned as well.
3597**
3598** [SQLITE_BUSY] means that the database engine was unable to acquire the
3599** database locks it needs to do its job.  If the statement is a [COMMIT]
3600** or occurs outside of an explicit transaction, then you can retry the
3601** statement.  If the statement is not a [COMMIT] and occurs within a
3602** explicit transaction then you should rollback the transaction before
3603** continuing.
3604**
3605** [SQLITE_DONE] means that the statement has finished executing
3606** successfully.  sqlite3_step() should not be called again on this virtual
3607** machine without first calling [sqlite3_reset()] to reset the virtual
3608** machine back to its initial state.
3609**
3610** If the SQL statement being executed returns any data, then [SQLITE_ROW]
3611** is returned each time a new row of data is ready for processing by the
3612** caller. The values may be accessed using the [column access functions].
3613** sqlite3_step() is called again to retrieve the next row of data.
3614**
3615** [SQLITE_ERROR] means that a run-time error (such as a constraint
3616** violation) has occurred.  sqlite3_step() should not be called again on
3617** the VM. More information may be found by calling [sqlite3_errmsg()].
3618** With the legacy interface, a more specific error code (for example,
3619** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
3620** can be obtained by calling [sqlite3_reset()] on the
3621** [prepared statement].  In the "v2" interface,
3622** the more specific error code is returned directly by sqlite3_step().
3623**
3624** [SQLITE_MISUSE] means that the this routine was called inappropriately.
3625** Perhaps it was called on a [prepared statement] that has
3626** already been [sqlite3_finalize | finalized] or on one that had
3627** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
3628** be the case that the same database connection is being used by two or
3629** more threads at the same moment in time.
3630**
3631** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
3632** API always returns a generic error code, [SQLITE_ERROR], following any
3633** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
3634** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
3635** specific [error codes] that better describes the error.
3636** We admit that this is a goofy design.  The problem has been fixed
3637** with the "v2" interface.  If you prepare all of your SQL statements
3638** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
3639** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
3640** then the more specific [error codes] are returned directly
3641** by sqlite3_step().  The use of the "v2" interface is recommended.
3642**
3643** INVARIANTS:
3644**
3645** {H13202}  If the [prepared statement] S is ready to be run, then
3646**           [sqlite3_step(S)] advances that prepared statement until
3647**           completion or until it is ready to return another row of the
3648**           result set, or until an [sqlite3_interrupt | interrupt]
3649**           or a run-time error occurs.
3650**
3651** {H15304}  When a call to [sqlite3_step(S)] causes the [prepared statement]
3652**           S to run to completion, the function returns [SQLITE_DONE].
3653**
3654** {H15306}  When a call to [sqlite3_step(S)] stops because it is ready to
3655**           return another row of the result set, it returns [SQLITE_ROW].
3656**
3657** {H15308}  If a call to [sqlite3_step(S)] encounters an
3658**           [sqlite3_interrupt | interrupt] or a run-time error,
3659**           it returns an appropriate error code that is not one of
3660**           [SQLITE_OK], [SQLITE_ROW], or [SQLITE_DONE].
3661**
3662** {H15310}  If an [sqlite3_interrupt | interrupt] or a run-time error
3663**           occurs during a call to [sqlite3_step(S)]
3664**           for a [prepared statement] S created using
3665**           legacy interfaces [sqlite3_prepare()] or
3666**           [sqlite3_prepare16()], then the function returns either
3667**           [SQLITE_ERROR], [SQLITE_BUSY], or [SQLITE_MISUSE].
3668*/
3669int sqlite3_step(sqlite3_stmt*);
3670
3671/*
3672** CAPI3REF: Number of columns in a result set {H13770} <S10700>
3673**
3674** Returns the number of values in the current row of the result set.
3675**
3676** INVARIANTS:
3677**
3678** {H13771}  After a call to [sqlite3_step(S)] that returns [SQLITE_ROW],
3679**           the [sqlite3_data_count(S)] routine will return the same value
3680**           as the [sqlite3_column_count(S)] function.
3681**
3682** {H13772}  After [sqlite3_step(S)] has returned any value other than
3683**           [SQLITE_ROW] or before [sqlite3_step(S)] has been called on the
3684**           [prepared statement] for the first time since it was
3685**           [sqlite3_prepare | prepared] or [sqlite3_reset | reset],
3686**           the [sqlite3_data_count(S)] routine returns zero.
3687*/
3688int sqlite3_data_count(sqlite3_stmt *pStmt);
3689
3690/*
3691** CAPI3REF: Fundamental Datatypes {H10265} <S10110><S10120>
3692** KEYWORDS: SQLITE_TEXT
3693**
3694** {H10266} Every value in SQLite has one of five fundamental datatypes:
3695**
3696** <ul>
3697** <li> 64-bit signed integer
3698** <li> 64-bit IEEE floating point number
3699** <li> string
3700** <li> BLOB
3701** <li> NULL
3702** </ul> {END}
3703**
3704** These constants are codes for each of those types.
3705**
3706** Note that the SQLITE_TEXT constant was also used in SQLite version 2
3707** for a completely different meaning.  Software that links against both
3708** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
3709** SQLITE_TEXT.
3710*/
3711#define SQLITE_INTEGER  1
3712#define SQLITE_FLOAT    2
3713#define SQLITE_BLOB     4
3714#define SQLITE_NULL     5
3715#ifdef SQLITE_TEXT
3716# undef SQLITE_TEXT
3717#else
3718# define SQLITE_TEXT     3
3719#endif
3720#define SQLITE3_TEXT     3
3721
3722/*
3723** CAPI3REF: Result Values From A Query {H13800} <S10700>
3724** KEYWORDS: {column access functions}
3725**
3726** These routines form the "result set query" interface.
3727**
3728** These routines return information about a single column of the current
3729** result row of a query.  In every case the first argument is a pointer
3730** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
3731** that was returned from [sqlite3_prepare_v2()] or one of its variants)
3732** and the second argument is the index of the column for which information
3733** should be returned.  The leftmost column of the result set has the index 0.
3734**
3735** If the SQL statement does not currently point to a valid row, or if the
3736** column index is out of range, the result is undefined.
3737** These routines may only be called when the most recent call to
3738** [sqlite3_step()] has returned [SQLITE_ROW] and neither
3739** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
3740** If any of these routines are called after [sqlite3_reset()] or
3741** [sqlite3_finalize()] or after [sqlite3_step()] has returned
3742** something other than [SQLITE_ROW], the results are undefined.
3743** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
3744** are called from a different thread while any of these routines
3745** are pending, then the results are undefined.
3746**
3747** The sqlite3_column_type() routine returns the
3748** [SQLITE_INTEGER | datatype code] for the initial data type
3749** of the result column.  The returned value is one of [SQLITE_INTEGER],
3750** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
3751** returned by sqlite3_column_type() is only meaningful if no type
3752** conversions have occurred as described below.  After a type conversion,
3753** the value returned by sqlite3_column_type() is undefined.  Future
3754** versions of SQLite may change the behavior of sqlite3_column_type()
3755** following a type conversion.
3756**
3757** If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
3758** routine returns the number of bytes in that BLOB or string.
3759** If the result is a UTF-16 string, then sqlite3_column_bytes() converts
3760** the string to UTF-8 and then returns the number of bytes.
3761** If the result is a numeric value then sqlite3_column_bytes() uses
3762** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
3763** the number of bytes in that string.
3764** The value returned does not include the zero terminator at the end
3765** of the string.  For clarity: the value returned is the number of
3766** bytes in the string, not the number of characters.
3767**
3768** Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
3769** even empty strings, are always zero terminated.  The return
3770** value from sqlite3_column_blob() for a zero-length BLOB is an arbitrary
3771** pointer, possibly even a NULL pointer.
3772**
3773** The sqlite3_column_bytes16() routine is similar to sqlite3_column_bytes()
3774** but leaves the result in UTF-16 in native byte order instead of UTF-8.
3775** The zero terminator is not included in this count.
3776**
3777** The object returned by [sqlite3_column_value()] is an
3778** [unprotected sqlite3_value] object.  An unprotected sqlite3_value object
3779** may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()].
3780** If the [unprotected sqlite3_value] object returned by
3781** [sqlite3_column_value()] is used in any other way, including calls
3782** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
3783** or [sqlite3_value_bytes()], then the behavior is undefined.
3784**
3785** These routines attempt to convert the value where appropriate.  For
3786** example, if the internal representation is FLOAT and a text result
3787** is requested, [sqlite3_snprintf()] is used internally to perform the
3788** conversion automatically.  The following table details the conversions
3789** that are applied:
3790**
3791** <blockquote>
3792** <table border="1">
3793** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
3794**
3795** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
3796** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
3797** <tr><td>  NULL    <td>   TEXT    <td> Result is NULL pointer
3798** <tr><td>  NULL    <td>   BLOB    <td> Result is NULL pointer
3799** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
3800** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
3801** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
3802** <tr><td>  FLOAT   <td> INTEGER   <td> Convert from float to integer
3803** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
3804** <tr><td>  FLOAT   <td>   BLOB    <td> Same as FLOAT->TEXT
3805** <tr><td>  TEXT    <td> INTEGER   <td> Use atoi()
3806** <tr><td>  TEXT    <td>  FLOAT    <td> Use atof()
3807** <tr><td>  TEXT    <td>   BLOB    <td> No change
3808** <tr><td>  BLOB    <td> INTEGER   <td> Convert to TEXT then use atoi()
3809** <tr><td>  BLOB    <td>  FLOAT    <td> Convert to TEXT then use atof()
3810** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
3811** </table>
3812** </blockquote>
3813**
3814** The table above makes reference to standard C library functions atoi()
3815** and atof().  SQLite does not really use these functions.  It has its
3816** own equivalent internal routines.  The atoi() and atof() names are
3817** used in the table for brevity and because they are familiar to most
3818** C programmers.
3819**
3820** Note that when type conversions occur, pointers returned by prior
3821** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
3822** sqlite3_column_text16() may be invalidated.
3823** Type conversions and pointer invalidations might occur
3824** in the following cases:
3825**
3826** <ul>
3827** <li> The initial content is a BLOB and sqlite3_column_text() or
3828**      sqlite3_column_text16() is called.  A zero-terminator might
3829**      need to be added to the string.</li>
3830** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
3831**      sqlite3_column_text16() is called.  The content must be converted
3832**      to UTF-16.</li>
3833** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
3834**      sqlite3_column_text() is called.  The content must be converted
3835**      to UTF-8.</li>
3836** </ul>
3837**
3838** Conversions between UTF-16be and UTF-16le are always done in place and do
3839** not invalidate a prior pointer, though of course the content of the buffer
3840** that the prior pointer points to will have been modified.  Other kinds
3841** of conversion are done in place when it is possible, but sometimes they
3842** are not possible and in those cases prior pointers are invalidated.
3843**
3844** The safest and easiest to remember policy is to invoke these routines
3845** in one of the following ways:
3846**
3847** <ul>
3848**  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
3849**  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
3850**  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
3851** </ul>
3852**
3853** In other words, you should call sqlite3_column_text(),
3854** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
3855** into the desired format, then invoke sqlite3_column_bytes() or
3856** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
3857** to sqlite3_column_text() or sqlite3_column_blob() with calls to
3858** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
3859** with calls to sqlite3_column_bytes().
3860**
3861** The pointers returned are valid until a type conversion occurs as
3862** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
3863** [sqlite3_finalize()] is called.  The memory space used to hold strings
3864** and BLOBs is freed automatically.  Do <b>not</b> pass the pointers returned
3865** [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
3866** [sqlite3_free()].
3867**
3868** If a memory allocation error occurs during the evaluation of any
3869** of these routines, a default value is returned.  The default value
3870** is either the integer 0, the floating point number 0.0, or a NULL
3871** pointer.  Subsequent calls to [sqlite3_errcode()] will return
3872** [SQLITE_NOMEM].
3873**
3874** INVARIANTS:
3875**
3876** {H13803} The [sqlite3_column_blob(S,N)] interface converts the
3877**          Nth column in the current row of the result set for
3878**          the [prepared statement] S into a BLOB and then returns a
3879**          pointer to the converted value.
3880**
3881** {H13806} The [sqlite3_column_bytes(S,N)] interface returns the
3882**          number of bytes in the BLOB or string (exclusive of the
3883**          zero terminator on the string) that was returned by the
3884**          most recent call to [sqlite3_column_blob(S,N)] or
3885**          [sqlite3_column_text(S,N)].
3886**
3887** {H13809} The [sqlite3_column_bytes16(S,N)] interface returns the
3888**          number of bytes in the string (exclusive of the
3889**          zero terminator on the string) that was returned by the
3890**          most recent call to [sqlite3_column_text16(S,N)].
3891**
3892** {H13812} The [sqlite3_column_double(S,N)] interface converts the
3893**          Nth column in the current row of the result set for the
3894**          [prepared statement] S into a floating point value and
3895**          returns a copy of that value.
3896**
3897** {H13815} The [sqlite3_column_int(S,N)] interface converts the
3898**          Nth column in the current row of the result set for the
3899**          [prepared statement] S into a 64-bit signed integer and
3900**          returns the lower 32 bits of that integer.
3901**
3902** {H13818} The [sqlite3_column_int64(S,N)] interface converts the
3903**          Nth column in the current row of the result set for the
3904**          [prepared statement] S into a 64-bit signed integer and
3905**          returns a copy of that integer.
3906**
3907** {H13821} The [sqlite3_column_text(S,N)] interface converts the
3908**          Nth column in the current row of the result set for
3909**          the [prepared statement] S into a zero-terminated UTF-8
3910**          string and returns a pointer to that string.
3911**
3912** {H13824} The [sqlite3_column_text16(S,N)] interface converts the
3913**          Nth column in the current row of the result set for the
3914**          [prepared statement] S into a zero-terminated 2-byte
3915**          aligned UTF-16 native byte order string and returns
3916**          a pointer to that string.
3917**
3918** {H13827} The [sqlite3_column_type(S,N)] interface returns
3919**          one of [SQLITE_NULL], [SQLITE_INTEGER], [SQLITE_FLOAT],
3920**          [SQLITE_TEXT], or [SQLITE_BLOB] as appropriate for
3921**          the Nth column in the current row of the result set for
3922**          the [prepared statement] S.
3923**
3924** {H13830} The [sqlite3_column_value(S,N)] interface returns a
3925**          pointer to an [unprotected sqlite3_value] object for the
3926**          Nth column in the current row of the result set for
3927**          the [prepared statement] S.
3928*/
3929const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
3930int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
3931int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
3932double sqlite3_column_double(sqlite3_stmt*, int iCol);
3933int sqlite3_column_int(sqlite3_stmt*, int iCol);
3934sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
3935const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
3936const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
3937int sqlite3_column_type(sqlite3_stmt*, int iCol);
3938sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
3939
3940/*
3941** CAPI3REF: Destroy A Prepared Statement Object {H13300} <S70300><S30100>
3942**
3943** The sqlite3_finalize() function is called to delete a [prepared statement].
3944** If the statement was executed successfully or not executed at all, then
3945** SQLITE_OK is returned. If execution of the statement failed then an
3946** [error code] or [extended error code] is returned.
3947**
3948** This routine can be called at any point during the execution of the
3949** [prepared statement].  If the virtual machine has not
3950** completed execution when this routine is called, that is like
3951** encountering an error or an [sqlite3_interrupt | interrupt].
3952** Incomplete updates may be rolled back and transactions canceled,
3953** depending on the circumstances, and the
3954** [error code] returned will be [SQLITE_ABORT].
3955**
3956** INVARIANTS:
3957**
3958** {H11302} The [sqlite3_finalize(S)] interface destroys the
3959**          [prepared statement] S and releases all
3960**          memory and file resources held by that object.
3961**
3962** {H11304} If the most recent call to [sqlite3_step(S)] for the
3963**          [prepared statement] S returned an error,
3964**          then [sqlite3_finalize(S)] returns that same error.
3965*/
3966int sqlite3_finalize(sqlite3_stmt *pStmt);
3967
3968/*
3969** CAPI3REF: Reset A Prepared Statement Object {H13330} <S70300>
3970**
3971** The sqlite3_reset() function is called to reset a [prepared statement]
3972** object back to its initial state, ready to be re-executed.
3973** Any SQL statement variables that had values bound to them using
3974** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
3975** Use [sqlite3_clear_bindings()] to reset the bindings.
3976**
3977** {H11332} The [sqlite3_reset(S)] interface resets the [prepared statement] S
3978**          back to the beginning of its program.
3979**
3980** {H11334} If the most recent call to [sqlite3_step(S)] for the
3981**          [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
3982**          or if [sqlite3_step(S)] has never before been called on S,
3983**          then [sqlite3_reset(S)] returns [SQLITE_OK].
3984**
3985** {H11336} If the most recent call to [sqlite3_step(S)] for the
3986**          [prepared statement] S indicated an error, then
3987**          [sqlite3_reset(S)] returns an appropriate [error code].
3988**
3989** {H11338} The [sqlite3_reset(S)] interface does not change the values
3990**          of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
3991*/
3992int sqlite3_reset(sqlite3_stmt *pStmt);
3993
3994/*
3995** CAPI3REF: Create Or Redefine SQL Functions {H16100} <S20200>
3996** KEYWORDS: {function creation routines}
3997** KEYWORDS: {application-defined SQL function}
3998** KEYWORDS: {application-defined SQL functions}
3999**
4000** These two functions (collectively known as "function creation routines")
4001** are used to add SQL functions or aggregates or to redefine the behavior
4002** of existing SQL functions or aggregates.  The only difference between the
4003** two is that the second parameter, the name of the (scalar) function or
4004** aggregate, is encoded in UTF-8 for sqlite3_create_function() and UTF-16
4005** for sqlite3_create_function16().
4006**
4007** The first parameter is the [database connection] to which the SQL
4008** function is to be added.  If a single program uses more than one database
4009** connection internally, then SQL functions must be added individually to
4010** each database connection.
4011**
4012** The second parameter is the name of the SQL function to be created or
4013** redefined.  The length of the name is limited to 255 bytes, exclusive of
4014** the zero-terminator.  Note that the name length limit is in bytes, not
4015** characters.  Any attempt to create a function with a longer name
4016** will result in [SQLITE_ERROR] being returned.
4017**
4018** The third parameter (nArg)
4019** is the number of arguments that the SQL function or
4020** aggregate takes. If this parameter is negative, then the SQL function or
4021** aggregate may take any number of arguments.
4022**
4023** The fourth parameter, eTextRep, specifies what
4024** [SQLITE_UTF8 | text encoding] this SQL function prefers for
4025** its parameters.  Any SQL function implementation should be able to work
4026** work with UTF-8, UTF-16le, or UTF-16be.  But some implementations may be
4027** more efficient with one encoding than another.  It is allowed to
4028** invoke sqlite3_create_function() or sqlite3_create_function16() multiple
4029** times with the same function but with different values of eTextRep.
4030** When multiple implementations of the same function are available, SQLite
4031** will pick the one that involves the least amount of data conversion.
4032** If there is only a single implementation which does not care what text
4033** encoding is used, then the fourth argument should be [SQLITE_ANY].
4034**
4035** The fifth parameter is an arbitrary pointer.  The implementation of the
4036** function can gain access to this pointer using [sqlite3_user_data()].
4037**
4038** The seventh, eighth and ninth parameters, xFunc, xStep and xFinal, are
4039** pointers to C-language functions that implement the SQL function or
4040** aggregate. A scalar SQL function requires an implementation of the xFunc
4041** callback only, NULL pointers should be passed as the xStep and xFinal
4042** parameters. An aggregate SQL function requires an implementation of xStep
4043** and xFinal and NULL should be passed for xFunc. To delete an existing
4044** SQL function or aggregate, pass NULL for all three function callbacks.
4045**
4046** It is permitted to register multiple implementations of the same
4047** functions with the same name but with either differing numbers of
4048** arguments or differing preferred text encodings.  SQLite will use
4049** the implementation most closely matches the way in which the
4050** SQL function is used.  A function implementation with a non-negative
4051** nArg parameter is a better match than a function implementation with
4052** a negative nArg.  A function where the preferred text encoding
4053** matches the database encoding is a better
4054** match than a function where the encoding is different.
4055** A function where the encoding difference is between UTF16le and UTF16be
4056** is a closer match than a function where the encoding difference is
4057** between UTF8 and UTF16.
4058**
4059** Built-in functions may be overloaded by new application-defined functions.
4060** The first application-defined function with a given name overrides all
4061** built-in functions in the same [database connection] with the same name.
4062** Subsequent application-defined functions of the same name only override
4063** prior application-defined functions that are an exact match for the
4064** number of parameters and preferred encoding.
4065**
4066** An application-defined function is permitted to call other
4067** SQLite interfaces.  However, such calls must not
4068** close the database connection nor finalize or reset the prepared
4069** statement in which the function is running.
4070**
4071** INVARIANTS:
4072**
4073** {H16103} The [sqlite3_create_function16(D,X,...)] interface shall behave
4074**          as [sqlite3_create_function(D,X,...)] in every way except that it
4075**          interprets the X argument as zero-terminated UTF-16
4076**          native byte order instead of as zero-terminated UTF-8.
4077**
4078** {H16106} A successful invocation of the
4079**          [sqlite3_create_function(D,X,N,E,...)] interface shall register
4080**          or replaces callback functions in the [database connection] D
4081**          used to implement the SQL function named X with N parameters
4082**          and having a preferred text encoding of E.
4083**
4084** {H16109} A successful call to [sqlite3_create_function(D,X,N,E,P,F,S,L)]
4085**          shall replace the P, F, S, and L values from any prior calls with
4086**          the same D, X, N, and E values.
4087**
4088** {H16112} The [sqlite3_create_function(D,X,...)] interface shall fail
4089**          if the SQL function name X is
4090**          longer than 255 bytes exclusive of the zero terminator.
4091**
4092** {H16118} The [sqlite3_create_function(D,X,N,E,P,F,S,L)] interface
4093**          shall fail unless either F is NULL and S and L are non-NULL or
4094***         F is non-NULL and S and L are NULL.
4095**
4096** {H16121} The [sqlite3_create_function(D,...)] interface shall fails with an
4097**          error code of [SQLITE_BUSY] if there exist [prepared statements]
4098**          associated with the [database connection] D.
4099**
4100** {H16124} The [sqlite3_create_function(D,X,N,...)] interface shall fail with
4101**          an error code of [SQLITE_ERROR] if parameter N is less
4102**          than -1 or greater than 127.
4103**
4104** {H16127} When N is non-negative, the [sqlite3_create_function(D,X,N,...)]
4105**          interface shall register callbacks to be invoked for the
4106**          SQL function
4107**          named X when the number of arguments to the SQL function is
4108**          exactly N.
4109**
4110** {H16130} When N is -1, the [sqlite3_create_function(D,X,N,...)]
4111**          interface shall register callbacks to be invoked for the SQL
4112**          function named X with any number of arguments.
4113**
4114** {H16133} When calls to [sqlite3_create_function(D,X,N,...)]
4115**          specify multiple implementations of the same function X
4116**          and when one implementation has N>=0 and the other has N=(-1)
4117**          the implementation with a non-zero N shall be preferred.
4118**
4119** {H16136} When calls to [sqlite3_create_function(D,X,N,E,...)]
4120**          specify multiple implementations of the same function X with
4121**          the same number of arguments N but with different
4122**          encodings E, then the implementation where E matches the
4123**          database encoding shall preferred.
4124**
4125** {H16139} For an aggregate SQL function created using
4126**          [sqlite3_create_function(D,X,N,E,P,0,S,L)] the finalizer
4127**          function L shall always be invoked exactly once if the
4128**          step function S is called one or more times.
4129**
4130** {H16142} When SQLite invokes either the xFunc or xStep function of
4131**          an application-defined SQL function or aggregate created
4132**          by [sqlite3_create_function()] or [sqlite3_create_function16()],
4133**          then the array of [sqlite3_value] objects passed as the
4134**          third parameter shall be [protected sqlite3_value] objects.
4135*/
4136int sqlite3_create_function(
4137  sqlite3 *db,
4138  const char *zFunctionName,
4139  int nArg,
4140  int eTextRep,
4141  void *pApp,
4142  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
4143  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
4144  void (*xFinal)(sqlite3_context*)
4145);
4146int sqlite3_create_function16(
4147  sqlite3 *db,
4148  const void *zFunctionName,
4149  int nArg,
4150  int eTextRep,
4151  void *pApp,
4152  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
4153  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
4154  void (*xFinal)(sqlite3_context*)
4155);
4156
4157/*
4158** CAPI3REF: Text Encodings {H10267} <S50200> <H16100>
4159**
4160** These constant define integer codes that represent the various
4161** text encodings supported by SQLite.
4162*/
4163#define SQLITE_UTF8           1
4164#define SQLITE_UTF16LE        2
4165#define SQLITE_UTF16BE        3
4166#define SQLITE_UTF16          4    /* Use native byte order */
4167#define SQLITE_ANY            5    /* sqlite3_create_function only */
4168#define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */
4169
4170/*
4171** CAPI3REF: Deprecated Functions
4172** DEPRECATED
4173**
4174** These functions are [deprecated].  In order to maintain
4175** backwards compatibility with older code, these functions continue
4176** to be supported.  However, new applications should avoid
4177** the use of these functions.  To help encourage people to avoid
4178** using these functions, we are not going to tell you what they do.
4179*/
4180#ifndef SQLITE_OMIT_DEPRECATED
4181SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
4182SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
4183SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
4184SQLITE_DEPRECATED int sqlite3_global_recover(void);
4185SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
4186SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),void*,sqlite3_int64);
4187#endif
4188
4189/*
4190** CAPI3REF: Obtaining SQL Function Parameter Values {H15100} <S20200>
4191**
4192** The C-language implementation of SQL functions and aggregates uses
4193** this set of interface routines to access the parameter values on
4194** the function or aggregate.
4195**
4196** The xFunc (for scalar functions) or xStep (for aggregates) parameters
4197** to [sqlite3_create_function()] and [sqlite3_create_function16()]
4198** define callbacks that implement the SQL functions and aggregates.
4199** The 4th parameter to these callbacks is an array of pointers to
4200** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
4201** each parameter to the SQL function.  These routines are used to
4202** extract values from the [sqlite3_value] objects.
4203**
4204** These routines work only with [protected sqlite3_value] objects.
4205** Any attempt to use these routines on an [unprotected sqlite3_value]
4206** object results in undefined behavior.
4207**
4208** These routines work just like the corresponding [column access functions]
4209** except that  these routines take a single [protected sqlite3_value] object
4210** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
4211**
4212** The sqlite3_value_text16() interface extracts a UTF-16 string
4213** in the native byte-order of the host machine.  The
4214** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
4215** extract UTF-16 strings as big-endian and little-endian respectively.
4216**
4217** The sqlite3_value_numeric_type() interface attempts to apply
4218** numeric affinity to the value.  This means that an attempt is
4219** made to convert the value to an integer or floating point.  If
4220** such a conversion is possible without loss of information (in other
4221** words, if the value is a string that looks like a number)
4222** then the conversion is performed.  Otherwise no conversion occurs.
4223** The [SQLITE_INTEGER | datatype] after conversion is returned.
4224**
4225** Please pay particular attention to the fact that the pointer returned
4226** from [sqlite3_value_blob()], [sqlite3_value_text()], or
4227** [sqlite3_value_text16()] can be invalidated by a subsequent call to
4228** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
4229** or [sqlite3_value_text16()].
4230**
4231** These routines must be called from the same thread as
4232** the SQL function that supplied the [sqlite3_value*] parameters.
4233**
4234** INVARIANTS:
4235**
4236** {H15103} The [sqlite3_value_blob(V)] interface converts the
4237**          [protected sqlite3_value] object V into a BLOB and then
4238**          returns a pointer to the converted value.
4239**
4240** {H15106} The [sqlite3_value_bytes(V)] interface returns the
4241**          number of bytes in the BLOB or string (exclusive of the
4242**          zero terminator on the string) that was returned by the
4243**          most recent call to [sqlite3_value_blob(V)] or
4244**          [sqlite3_value_text(V)].
4245**
4246** {H15109} The [sqlite3_value_bytes16(V)] interface returns the
4247**          number of bytes in the string (exclusive of the
4248**          zero terminator on the string) that was returned by the
4249**          most recent call to [sqlite3_value_text16(V)],
4250**          [sqlite3_value_text16be(V)], or [sqlite3_value_text16le(V)].
4251**
4252** {H15112} The [sqlite3_value_double(V)] interface converts the
4253**          [protected sqlite3_value] object V into a floating point value and
4254**          returns a copy of that value.
4255**
4256** {H15115} The [sqlite3_value_int(V)] interface converts the
4257**          [protected sqlite3_value] object V into a 64-bit signed integer and
4258**          returns the lower 32 bits of that integer.
4259**
4260** {H15118} The [sqlite3_value_int64(V)] interface converts the
4261**          [protected sqlite3_value] object V into a 64-bit signed integer and
4262**          returns a copy of that integer.
4263**
4264** {H15121} The [sqlite3_value_text(V)] interface converts the
4265**          [protected sqlite3_value] object V into a zero-terminated UTF-8
4266**          string and returns a pointer to that string.
4267**
4268** {H15124} The [sqlite3_value_text16(V)] interface converts the
4269**          [protected sqlite3_value] object V into a zero-terminated 2-byte
4270**          aligned UTF-16 native byte order
4271**          string and returns a pointer to that string.
4272**
4273** {H15127} The [sqlite3_value_text16be(V)] interface converts the
4274**          [protected sqlite3_value] object V into a zero-terminated 2-byte
4275**          aligned UTF-16 big-endian
4276**          string and returns a pointer to that string.
4277**
4278** {H15130} The [sqlite3_value_text16le(V)] interface converts the
4279**          [protected sqlite3_value] object V into a zero-terminated 2-byte
4280**          aligned UTF-16 little-endian
4281**          string and returns a pointer to that string.
4282**
4283** {H15133} The [sqlite3_value_type(V)] interface returns
4284**          one of [SQLITE_NULL], [SQLITE_INTEGER], [SQLITE_FLOAT],
4285**          [SQLITE_TEXT], or [SQLITE_BLOB] as appropriate for
4286**          the [sqlite3_value] object V.
4287**
4288** {H15136} The [sqlite3_value_numeric_type(V)] interface converts
4289**          the [protected sqlite3_value] object V into either an integer or
4290**          a floating point value if it can do so without loss of
4291**          information, and returns one of [SQLITE_NULL],
4292**          [SQLITE_INTEGER], [SQLITE_FLOAT], [SQLITE_TEXT], or
4293**          [SQLITE_BLOB] as appropriate for the
4294**          [protected sqlite3_value] object V after the conversion attempt.
4295*/
4296const void *sqlite3_value_blob(sqlite3_value*);
4297int sqlite3_value_bytes(sqlite3_value*);
4298int sqlite3_value_bytes16(sqlite3_value*);
4299double sqlite3_value_double(sqlite3_value*);
4300int sqlite3_value_int(sqlite3_value*);
4301sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
4302const unsigned char *sqlite3_value_text(sqlite3_value*);
4303const void *sqlite3_value_text16(sqlite3_value*);
4304const void *sqlite3_value_text16le(sqlite3_value*);
4305const void *sqlite3_value_text16be(sqlite3_value*);
4306int sqlite3_value_type(sqlite3_value*);
4307int sqlite3_value_numeric_type(sqlite3_value*);
4308
4309/*
4310** CAPI3REF: Obtain Aggregate Function Context {H16210} <S20200>
4311**
4312** The implementation of aggregate SQL functions use this routine to allocate
4313** a structure for storing their state.
4314**
4315** The first time the sqlite3_aggregate_context() routine is called for a
4316** particular aggregate, SQLite allocates nBytes of memory, zeroes out that
4317** memory, and returns a pointer to it. On second and subsequent calls to
4318** sqlite3_aggregate_context() for the same aggregate function index,
4319** the same buffer is returned. The implementation of the aggregate can use
4320** the returned buffer to accumulate data.
4321**
4322** SQLite automatically frees the allocated buffer when the aggregate
4323** query concludes.
4324**
4325** The first parameter should be a copy of the
4326** [sqlite3_context | SQL function context] that is the first parameter
4327** to the callback routine that implements the aggregate function.
4328**
4329** This routine must be called from the same thread in which
4330** the aggregate SQL function is running.
4331**
4332** INVARIANTS:
4333**
4334** {H16211} The first invocation of [sqlite3_aggregate_context(C,N)] for
4335**          a particular instance of an aggregate function (for a particular
4336**          context C) causes SQLite to allocate N bytes of memory,
4337**          zero that memory, and return a pointer to the allocated memory.
4338**
4339** {H16213} If a memory allocation error occurs during
4340**          [sqlite3_aggregate_context(C,N)] then the function returns 0.
4341**
4342** {H16215} Second and subsequent invocations of
4343**          [sqlite3_aggregate_context(C,N)] for the same context pointer C
4344**          ignore the N parameter and return a pointer to the same
4345**          block of memory returned by the first invocation.
4346**
4347** {H16217} The memory allocated by [sqlite3_aggregate_context(C,N)] is
4348**          automatically freed on the next call to [sqlite3_reset()]
4349**          or [sqlite3_finalize()] for the [prepared statement] containing
4350**          the aggregate function associated with context C.
4351*/
4352void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);
4353
4354/*
4355** CAPI3REF: User Data For Functions {H16240} <S20200>
4356**
4357** The sqlite3_user_data() interface returns a copy of
4358** the pointer that was the pUserData parameter (the 5th parameter)
4359** of the [sqlite3_create_function()]
4360** and [sqlite3_create_function16()] routines that originally
4361** registered the application defined function. {END}
4362**
4363** This routine must be called from the same thread in which
4364** the application-defined function is running.
4365**
4366** INVARIANTS:
4367**
4368** {H16243} The [sqlite3_user_data(C)] interface returns a copy of the
4369**          P pointer from the [sqlite3_create_function(D,X,N,E,P,F,S,L)]
4370**          or [sqlite3_create_function16(D,X,N,E,P,F,S,L)] call that
4371**          registered the SQL function associated with [sqlite3_context] C.
4372*/
4373void *sqlite3_user_data(sqlite3_context*);
4374
4375/*
4376** CAPI3REF: Database Connection For Functions {H16250} <S60600><S20200>
4377**
4378** The sqlite3_context_db_handle() interface returns a copy of
4379** the pointer to the [database connection] (the 1st parameter)
4380** of the [sqlite3_create_function()]
4381** and [sqlite3_create_function16()] routines that originally
4382** registered the application defined function.
4383**
4384** INVARIANTS:
4385**
4386** {H16253} The [sqlite3_context_db_handle(C)] interface returns a copy of the
4387**          D pointer from the [sqlite3_create_function(D,X,N,E,P,F,S,L)]
4388**          or [sqlite3_create_function16(D,X,N,E,P,F,S,L)] call that
4389**          registered the SQL function associated with [sqlite3_context] C.
4390*/
4391sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
4392
4393/*
4394** CAPI3REF: Function Auxiliary Data {H16270} <S20200>
4395**
4396** The following two functions may be used by scalar SQL functions to
4397** associate metadata with argument values. If the same value is passed to
4398** multiple invocations of the same SQL function during query execution, under
4399** some circumstances the associated metadata may be preserved. This may
4400** be used, for example, to add a regular-expression matching scalar
4401** function. The compiled version of the regular expression is stored as
4402** metadata associated with the SQL value passed as the regular expression
4403** pattern.  The compiled regular expression can be reused on multiple
4404** invocations of the same function so that the original pattern string
4405** does not need to be recompiled on each invocation.
4406**
4407** The sqlite3_get_auxdata() interface returns a pointer to the metadata
4408** associated by the sqlite3_set_auxdata() function with the Nth argument
4409** value to the application-defined function. If no metadata has been ever
4410** been set for the Nth argument of the function, or if the corresponding
4411** function parameter has changed since the meta-data was set,
4412** then sqlite3_get_auxdata() returns a NULL pointer.
4413**
4414** The sqlite3_set_auxdata() interface saves the metadata
4415** pointed to by its 3rd parameter as the metadata for the N-th
4416** argument of the application-defined function.  Subsequent
4417** calls to sqlite3_get_auxdata() might return this data, if it has
4418** not been destroyed.
4419** If it is not NULL, SQLite will invoke the destructor
4420** function given by the 4th parameter to sqlite3_set_auxdata() on
4421** the metadata when the corresponding function parameter changes
4422** or when the SQL statement completes, whichever comes first.
4423**
4424** SQLite is free to call the destructor and drop metadata on any
4425** parameter of any function at any time.  The only guarantee is that
4426** the destructor will be called before the metadata is dropped.
4427**
4428** In practice, metadata is preserved between function calls for
4429** expressions that are constant at compile time. This includes literal
4430** values and SQL variables.
4431**
4432** These routines must be called from the same thread in which
4433** the SQL function is running.
4434**
4435** INVARIANTS:
4436**
4437** {H16272} The [sqlite3_get_auxdata(C,N)] interface returns a pointer
4438**          to metadata associated with the Nth parameter of the SQL function
4439**          whose context is C, or NULL if there is no metadata associated
4440**          with that parameter.
4441**
4442** {H16274} The [sqlite3_set_auxdata(C,N,P,D)] interface assigns a metadata
4443**          pointer P to the Nth parameter of the SQL function with context C.
4444**
4445** {H16276} SQLite will invoke the destructor D with a single argument
4446**          which is the metadata pointer P following a call to
4447**          [sqlite3_set_auxdata(C,N,P,D)] when SQLite ceases to hold
4448**          the metadata.
4449**
4450** {H16277} SQLite ceases to hold metadata for an SQL function parameter
4451**          when the value of that parameter changes.
4452**
4453** {H16278} When [sqlite3_set_auxdata(C,N,P,D)] is invoked, the destructor
4454**          is called for any prior metadata associated with the same function
4455**          context C and parameter N.
4456**
4457** {H16279} SQLite will call destructors for any metadata it is holding
4458**          in a particular [prepared statement] S when either
4459**          [sqlite3_reset(S)] or [sqlite3_finalize(S)] is called.
4460*/
4461void *sqlite3_get_auxdata(sqlite3_context*, int N);
4462void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
4463
4464
4465/*
4466** CAPI3REF: Constants Defining Special Destructor Behavior {H10280} <S30100>
4467**
4468** These are special values for the destructor that is passed in as the
4469** final argument to routines like [sqlite3_result_blob()].  If the destructor
4470** argument is SQLITE_STATIC, it means that the content pointer is constant
4471** and will never change.  It does not need to be destroyed.  The
4472** SQLITE_TRANSIENT value means that the content will likely change in
4473** the near future and that SQLite should make its own private copy of
4474** the content before returning.
4475**
4476** The typedef is necessary to work around problems in certain
4477** C++ compilers.  See ticket #2191.
4478*/
4479typedef void (*sqlite3_destructor_type)(void*);
4480#define SQLITE_STATIC      ((sqlite3_destructor_type)0)
4481#define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)
4482
4483/*
4484** CAPI3REF: Setting The Result Of An SQL Function {H16400} <S20200>
4485**
4486** These routines are used by the xFunc or xFinal callbacks that
4487** implement SQL functions and aggregates.  See
4488** [sqlite3_create_function()] and [sqlite3_create_function16()]
4489** for additional information.
4490**
4491** These functions work very much like the [parameter binding] family of
4492** functions used to bind values to host parameters in prepared statements.
4493** Refer to the [SQL parameter] documentation for additional information.
4494**
4495** The sqlite3_result_blob() interface sets the result from
4496** an application-defined function to be the BLOB whose content is pointed
4497** to by the second parameter and which is N bytes long where N is the
4498** third parameter.
4499**
4500** The sqlite3_result_zeroblob() interfaces set the result of
4501** the application-defined function to be a BLOB containing all zero
4502** bytes and N bytes in size, where N is the value of the 2nd parameter.
4503**
4504** The sqlite3_result_double() interface sets the result from
4505** an application-defined function to be a floating point value specified
4506** by its 2nd argument.
4507**
4508** The sqlite3_result_error() and sqlite3_result_error16() functions
4509** cause the implemented SQL function to throw an exception.
4510** SQLite uses the string pointed to by the
4511** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
4512** as the text of an error message.  SQLite interprets the error
4513** message string from sqlite3_result_error() as UTF-8. SQLite
4514** interprets the string from sqlite3_result_error16() as UTF-16 in native
4515** byte order.  If the third parameter to sqlite3_result_error()
4516** or sqlite3_result_error16() is negative then SQLite takes as the error
4517** message all text up through the first zero character.
4518** If the third parameter to sqlite3_result_error() or
4519** sqlite3_result_error16() is non-negative then SQLite takes that many
4520** bytes (not characters) from the 2nd parameter as the error message.
4521** The sqlite3_result_error() and sqlite3_result_error16()
4522** routines make a private copy of the error message text before
4523** they return.  Hence, the calling function can deallocate or
4524** modify the text after they return without harm.
4525** The sqlite3_result_error_code() function changes the error code
4526** returned by SQLite as a result of an error in a function.  By default,
4527** the error code is SQLITE_ERROR.  A subsequent call to sqlite3_result_error()
4528** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
4529**
4530** The sqlite3_result_toobig() interface causes SQLite to throw an error
4531** indicating that a string or BLOB is to long to represent.
4532**
4533** The sqlite3_result_nomem() interface causes SQLite to throw an error
4534** indicating that a memory allocation failed.
4535**
4536** The sqlite3_result_int() interface sets the return value
4537** of the application-defined function to be the 32-bit signed integer
4538** value given in the 2nd argument.
4539** The sqlite3_result_int64() interface sets the return value
4540** of the application-defined function to be the 64-bit signed integer
4541** value given in the 2nd argument.
4542**
4543** The sqlite3_result_null() interface sets the return value
4544** of the application-defined function to be NULL.
4545**
4546** The sqlite3_result_text(), sqlite3_result_text16(),
4547** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
4548** set the return value of the application-defined function to be
4549** a text string which is represented as UTF-8, UTF-16 native byte order,
4550** UTF-16 little endian, or UTF-16 big endian, respectively.
4551** SQLite takes the text result from the application from
4552** the 2nd parameter of the sqlite3_result_text* interfaces.
4553** If the 3rd parameter to the sqlite3_result_text* interfaces
4554** is negative, then SQLite takes result text from the 2nd parameter
4555** through the first zero character.
4556** If the 3rd parameter to the sqlite3_result_text* interfaces
4557** is non-negative, then as many bytes (not characters) of the text
4558** pointed to by the 2nd parameter are taken as the application-defined
4559** function result.
4560** If the 4th parameter to the sqlite3_result_text* interfaces
4561** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
4562** function as the destructor on the text or BLOB result when it has
4563** finished using that result.
4564** If the 4th parameter to the sqlite3_result_text* interfaces or
4565** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
4566** assumes that the text or BLOB result is in constant space and does not
4567** copy the it or call a destructor when it has finished using that result.
4568** If the 4th parameter to the sqlite3_result_text* interfaces
4569** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
4570** then SQLite makes a copy of the result into space obtained from
4571** from [sqlite3_malloc()] before it returns.
4572**
4573** The sqlite3_result_value() interface sets the result of
4574** the application-defined function to be a copy the
4575** [unprotected sqlite3_value] object specified by the 2nd parameter.  The
4576** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
4577** so that the [sqlite3_value] specified in the parameter may change or
4578** be deallocated after sqlite3_result_value() returns without harm.
4579** A [protected sqlite3_value] object may always be used where an
4580** [unprotected sqlite3_value] object is required, so either
4581** kind of [sqlite3_value] object can be used with this interface.
4582**
4583** If these routines are called from within the different thread
4584** than the one containing the application-defined function that received
4585** the [sqlite3_context] pointer, the results are undefined.
4586**
4587** INVARIANTS:
4588**
4589** {H16403} The default return value from any SQL function is NULL.
4590**
4591** {H16406} The [sqlite3_result_blob(C,V,N,D)] interface changes the
4592**          return value of function C to be a BLOB that is N bytes
4593**          in length and with content pointed to by V.
4594**
4595** {H16409} The [sqlite3_result_double(C,V)] interface changes the
4596**          return value of function C to be the floating point value V.
4597**
4598** {H16412} The [sqlite3_result_error(C,V,N)] interface changes the return
4599**          value of function C to be an exception with error code
4600**          [SQLITE_ERROR] and a UTF-8 error message copied from V up to the
4601**          first zero byte or until N bytes are read if N is positive.
4602**
4603** {H16415} The [sqlite3_result_error16(C,V,N)] interface changes the return
4604**          value of function C to be an exception with error code
4605**          [SQLITE_ERROR] and a UTF-16 native byte order error message
4606**          copied from V up to the first zero terminator or until N bytes
4607**          are read if N is positive.
4608**
4609** {H16418} The [sqlite3_result_error_toobig(C)] interface changes the return
4610**          value of the function C to be an exception with error code
4611**          [SQLITE_TOOBIG] and an appropriate error message.
4612**
4613** {H16421} The [sqlite3_result_error_nomem(C)] interface changes the return
4614**          value of the function C to be an exception with error code
4615**          [SQLITE_NOMEM] and an appropriate error message.
4616**
4617** {H16424} The [sqlite3_result_error_code(C,E)] interface changes the return
4618**          value of the function C to be an exception with error code E.
4619**          The error message text is unchanged.
4620**
4621** {H16427} The [sqlite3_result_int(C,V)] interface changes the
4622**          return value of function C to be the 32-bit integer value V.
4623**
4624** {H16430} The [sqlite3_result_int64(C,V)] interface changes the
4625**          return value of function C to be the 64-bit integer value V.
4626**
4627** {H16433} The [sqlite3_result_null(C)] interface changes the
4628**          return value of function C to be NULL.
4629**
4630** {H16436} The [sqlite3_result_text(C,V,N,D)] interface changes the
4631**          return value of function C to be the UTF-8 string
4632**          V up to the first zero if N is negative
4633**          or the first N bytes of V if N is non-negative.
4634**
4635** {H16439} The [sqlite3_result_text16(C,V,N,D)] interface changes the
4636**          return value of function C to be the UTF-16 native byte order
4637**          string V up to the first zero if N is negative
4638**          or the first N bytes of V if N is non-negative.
4639**
4640** {H16442} The [sqlite3_result_text16be(C,V,N,D)] interface changes the
4641**          return value of function C to be the UTF-16 big-endian
4642**          string V up to the first zero if N is negative
4643**          or the first N bytes or V if N is non-negative.
4644**
4645** {H16445} The [sqlite3_result_text16le(C,V,N,D)] interface changes the
4646**          return value of function C to be the UTF-16 little-endian
4647**          string V up to the first zero if N is negative
4648**          or the first N bytes of V if N is non-negative.
4649**
4650** {H16448} The [sqlite3_result_value(C,V)] interface changes the
4651**          return value of function C to be the [unprotected sqlite3_value]
4652**          object V.
4653**
4654** {H16451} The [sqlite3_result_zeroblob(C,N)] interface changes the
4655**          return value of function C to be an N-byte BLOB of all zeros.
4656**
4657** {H16454} The [sqlite3_result_error()] and [sqlite3_result_error16()]
4658**          interfaces make a copy of their error message strings before
4659**          returning.
4660**
4661** {H16457} If the D destructor parameter to [sqlite3_result_blob(C,V,N,D)],
4662**          [sqlite3_result_text(C,V,N,D)], [sqlite3_result_text16(C,V,N,D)],
4663**          [sqlite3_result_text16be(C,V,N,D)], or
4664**          [sqlite3_result_text16le(C,V,N,D)] is the constant [SQLITE_STATIC]
4665**          then no destructor is ever called on the pointer V and SQLite
4666**          assumes that V is immutable.
4667**
4668** {H16460} If the D destructor parameter to [sqlite3_result_blob(C,V,N,D)],
4669**          [sqlite3_result_text(C,V,N,D)], [sqlite3_result_text16(C,V,N,D)],
4670**          [sqlite3_result_text16be(C,V,N,D)], or
4671**          [sqlite3_result_text16le(C,V,N,D)] is the constant
4672**          [SQLITE_TRANSIENT] then the interfaces makes a copy of the
4673**          content of V and retains the copy.
4674**
4675** {H16463} If the D destructor parameter to [sqlite3_result_blob(C,V,N,D)],
4676**          [sqlite3_result_text(C,V,N,D)], [sqlite3_result_text16(C,V,N,D)],
4677**          [sqlite3_result_text16be(C,V,N,D)], or
4678**          [sqlite3_result_text16le(C,V,N,D)] is some value other than
4679**          the constants [SQLITE_STATIC] and [SQLITE_TRANSIENT] then
4680**          SQLite will invoke the destructor D with V as its only argument
4681**          when it has finished with the V value.
4682*/
4683void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
4684void sqlite3_result_double(sqlite3_context*, double);
4685void sqlite3_result_error(sqlite3_context*, const char*, int);
4686void sqlite3_result_error16(sqlite3_context*, const void*, int);
4687void sqlite3_result_error_toobig(sqlite3_context*);
4688void sqlite3_result_error_nomem(sqlite3_context*);
4689void sqlite3_result_error_code(sqlite3_context*, int);
4690void sqlite3_result_int(sqlite3_context*, int);
4691void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
4692void sqlite3_result_null(sqlite3_context*);
4693void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
4694void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
4695void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
4696void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
4697void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
4698void sqlite3_result_zeroblob(sqlite3_context*, int n);
4699
4700/*
4701** CAPI3REF: Define New Collating Sequences {H16600} <S20300>
4702**
4703** These functions are used to add new collation sequences to the
4704** [database connection] specified as the first argument.
4705**
4706** The name of the new collation sequence is specified as a UTF-8 string
4707** for sqlite3_create_collation() and sqlite3_create_collation_v2()
4708** and a UTF-16 string for sqlite3_create_collation16(). In all cases
4709** the name is passed as the second function argument.
4710**
4711** The third argument may be one of the constants [SQLITE_UTF8],
4712** [SQLITE_UTF16LE] or [SQLITE_UTF16BE], indicating that the user-supplied
4713** routine expects to be passed pointers to strings encoded using UTF-8,
4714** UTF-16 little-endian, or UTF-16 big-endian, respectively. The
4715** third argument might also be [SQLITE_UTF16_ALIGNED] to indicate that
4716** the routine expects pointers to 16-bit word aligned strings
4717** of UTF-16 in the native byte order of the host computer.
4718**
4719** A pointer to the user supplied routine must be passed as the fifth
4720** argument.  If it is NULL, this is the same as deleting the collation
4721** sequence (so that SQLite cannot call it anymore).
4722** Each time the application supplied function is invoked, it is passed
4723** as its first parameter a copy of the void* passed as the fourth argument
4724** to sqlite3_create_collation() or sqlite3_create_collation16().
4725**
4726** The remaining arguments to the application-supplied routine are two strings,
4727** each represented by a (length, data) pair and encoded in the encoding
4728** that was passed as the third argument when the collation sequence was
4729** registered. {END}  The application defined collation routine should
4730** return negative, zero or positive if the first string is less than,
4731** equal to, or greater than the second string. i.e. (STRING1 - STRING2).
4732**
4733** The sqlite3_create_collation_v2() works like sqlite3_create_collation()
4734** except that it takes an extra argument which is a destructor for
4735** the collation.  The destructor is called when the collation is
4736** destroyed and is passed a copy of the fourth parameter void* pointer
4737** of the sqlite3_create_collation_v2().
4738** Collations are destroyed when they are overridden by later calls to the
4739** collation creation functions or when the [database connection] is closed
4740** using [sqlite3_close()].
4741**
4742** INVARIANTS:
4743**
4744** {H16603} A successful call to the
4745**          [sqlite3_create_collation_v2(B,X,E,P,F,D)] interface
4746**          registers function F as the comparison function used to
4747**          implement collation X on the [database connection] B for
4748**          databases having encoding E.
4749**
4750** {H16604} SQLite understands the X parameter to
4751**          [sqlite3_create_collation_v2(B,X,E,P,F,D)] as a zero-terminated
4752**          UTF-8 string in which case is ignored for ASCII characters and
4753**          is significant for non-ASCII characters.
4754**
4755** {H16606} Successive calls to [sqlite3_create_collation_v2(B,X,E,P,F,D)]
4756**          with the same values for B, X, and E, override prior values
4757**          of P, F, and D.
4758**
4759** {H16609} If the destructor D in [sqlite3_create_collation_v2(B,X,E,P,F,D)]
4760**          is not NULL then it is called with argument P when the
4761**          collating function is dropped by SQLite.
4762**
4763** {H16612} A collating function is dropped when it is overloaded.
4764**
4765** {H16615} A collating function is dropped when the database connection
4766**          is closed using [sqlite3_close()].
4767**
4768** {H16618} The pointer P in [sqlite3_create_collation_v2(B,X,E,P,F,D)]
4769**          is passed through as the first parameter to the comparison
4770**          function F for all subsequent invocations of F.
4771**
4772** {H16621} A call to [sqlite3_create_collation(B,X,E,P,F)] is exactly
4773**          the same as a call to [sqlite3_create_collation_v2()] with
4774**          the same parameters and a NULL destructor.
4775**
4776** {H16624} Following a [sqlite3_create_collation_v2(B,X,E,P,F,D)],
4777**          SQLite uses the comparison function F for all text comparison
4778**          operations on the [database connection] B on text values that
4779**          use the collating sequence named X.
4780**
4781** {H16627} The [sqlite3_create_collation16(B,X,E,P,F)] works the same
4782**          as [sqlite3_create_collation(B,X,E,P,F)] except that the
4783**          collation name X is understood as UTF-16 in native byte order
4784**          instead of UTF-8.
4785**
4786** {H16630} When multiple comparison functions are available for the same
4787**          collating sequence, SQLite chooses the one whose text encoding
4788**          requires the least amount of conversion from the default
4789**          text encoding of the database.
4790*/
4791int sqlite3_create_collation(
4792  sqlite3*,
4793  const char *zName,
4794  int eTextRep,
4795  void*,
4796  int(*xCompare)(void*,int,const void*,int,const void*)
4797);
4798int sqlite3_create_collation_v2(
4799  sqlite3*,
4800  const char *zName,
4801  int eTextRep,
4802  void*,
4803  int(*xCompare)(void*,int,const void*,int,const void*),
4804  void(*xDestroy)(void*)
4805);
4806int sqlite3_create_collation16(
4807  sqlite3*,
4808  const void *zName,
4809  int eTextRep,
4810  void*,
4811  int(*xCompare)(void*,int,const void*,int,const void*)
4812);
4813
4814/*
4815** CAPI3REF: Collation Needed Callbacks {H16700} <S20300>
4816**
4817** To avoid having to register all collation sequences before a database
4818** can be used, a single callback function may be registered with the
4819** [database connection] to be called whenever an undefined collation
4820** sequence is required.
4821**
4822** If the function is registered using the sqlite3_collation_needed() API,
4823** then it is passed the names of undefined collation sequences as strings
4824** encoded in UTF-8. {H16703} If sqlite3_collation_needed16() is used,
4825** the names are passed as UTF-16 in machine native byte order.
4826** A call to either function replaces any existing callback.
4827**
4828** When the callback is invoked, the first argument passed is a copy
4829** of the second argument to sqlite3_collation_needed() or
4830** sqlite3_collation_needed16().  The second argument is the database
4831** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
4832** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
4833** sequence function required.  The fourth parameter is the name of the
4834** required collation sequence.
4835**
4836** The callback function should register the desired collation using
4837** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
4838** [sqlite3_create_collation_v2()].
4839**
4840** INVARIANTS:
4841**
4842** {H16702} A successful call to [sqlite3_collation_needed(D,P,F)]
4843**          or [sqlite3_collation_needed16(D,P,F)] causes
4844**          the [database connection] D to invoke callback F with first
4845**          parameter P whenever it needs a comparison function for a
4846**          collating sequence that it does not know about.
4847**
4848** {H16704} Each successful call to [sqlite3_collation_needed()] or
4849**          [sqlite3_collation_needed16()] overrides the callback registered
4850**          on the same [database connection] by prior calls to either
4851**          interface.
4852**
4853** {H16706} The name of the requested collating function passed in the
4854**          4th parameter to the callback is in UTF-8 if the callback
4855**          was registered using [sqlite3_collation_needed()] and
4856**          is in UTF-16 native byte order if the callback was
4857**          registered using [sqlite3_collation_needed16()].
4858*/
4859int sqlite3_collation_needed(
4860  sqlite3*,
4861  void*,
4862  void(*)(void*,sqlite3*,int eTextRep,const char*)
4863);
4864int sqlite3_collation_needed16(
4865  sqlite3*,
4866  void*,
4867  void(*)(void*,sqlite3*,int eTextRep,const void*)
4868);
4869
4870/*
4871** Specify the key for an encrypted database.  This routine should be
4872** called right after sqlite3_open().
4873**
4874** The code to implement this API is not available in the public release
4875** of SQLite.
4876*/
4877int sqlite3_key(
4878  sqlite3 *db,                   /* Database to be rekeyed */
4879  const void *pKey, int nKey     /* The key */
4880);
4881
4882/*
4883** Change the key on an open database.  If the current database is not
4884** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
4885** database is decrypted.
4886**
4887** The code to implement this API is not available in the public release
4888** of SQLite.
4889*/
4890int sqlite3_rekey(
4891  sqlite3 *db,                   /* Database to be rekeyed */
4892  const void *pKey, int nKey     /* The new key */
4893);
4894
4895/*
4896** CAPI3REF: Suspend Execution For A Short Time {H10530} <S40410>
4897**
4898** The sqlite3_sleep() function causes the current thread to suspend execution
4899** for at least a number of milliseconds specified in its parameter.
4900**
4901** If the operating system does not support sleep requests with
4902** millisecond time resolution, then the time will be rounded up to
4903** the nearest second. The number of milliseconds of sleep actually
4904** requested from the operating system is returned.
4905**
4906** SQLite implements this interface by calling the xSleep()
4907** method of the default [sqlite3_vfs] object.
4908**
4909** INVARIANTS:
4910**
4911** {H10533} The [sqlite3_sleep(M)] interface invokes the xSleep
4912**          method of the default [sqlite3_vfs|VFS] in order to
4913**          suspend execution of the current thread for at least
4914**          M milliseconds.
4915**
4916** {H10536} The [sqlite3_sleep(M)] interface returns the number of
4917**          milliseconds of sleep actually requested of the operating
4918**          system, which might be larger than the parameter M.
4919*/
4920int sqlite3_sleep(int);
4921
4922/*
4923** CAPI3REF: Name Of The Folder Holding Temporary Files {H10310} <S20000>
4924**
4925** If this global variable is made to point to a string which is
4926** the name of a folder (a.k.a. directory), then all temporary files
4927** created by SQLite will be placed in that directory.  If this variable
4928** is a NULL pointer, then SQLite performs a search for an appropriate
4929** temporary file directory.
4930**
4931** It is not safe to modify this variable once a [database connection]
4932** has been opened.  It is intended that this variable be set once
4933** as part of process initialization and before any SQLite interface
4934** routines have been call and remain unchanged thereafter.
4935*/
4936SQLITE_EXTERN char *sqlite3_temp_directory;
4937
4938/*
4939** CAPI3REF: Test For Auto-Commit Mode {H12930} <S60200>
4940** KEYWORDS: {autocommit mode}
4941**
4942** The sqlite3_get_autocommit() interface returns non-zero or
4943** zero if the given database connection is or is not in autocommit mode,
4944** respectively.  Autocommit mode is on by default.
4945** Autocommit mode is disabled by a [BEGIN] statement.
4946** Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
4947**
4948** If certain kinds of errors occur on a statement within a multi-statement
4949** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
4950** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
4951** transaction might be rolled back automatically.  The only way to
4952** find out whether SQLite automatically rolled back the transaction after
4953** an error is to use this function.
4954**
4955** INVARIANTS:
4956**
4957** {H12931} The [sqlite3_get_autocommit(D)] interface returns non-zero or
4958**          zero if the [database connection] D is or is not in autocommit
4959**          mode, respectively.
4960**
4961** {H12932} Autocommit mode is on by default.
4962**
4963** {H12933} Autocommit mode is disabled by a successful [BEGIN] statement.
4964**
4965** {H12934} Autocommit mode is enabled by a successful [COMMIT] or [ROLLBACK]
4966**          statement.
4967**
4968** ASSUMPTIONS:
4969**
4970** {A12936} If another thread changes the autocommit status of the database
4971**          connection while this routine is running, then the return value
4972**          is undefined.
4973*/
4974int sqlite3_get_autocommit(sqlite3*);
4975
4976/*
4977** CAPI3REF: Find The Database Handle Of A Prepared Statement {H13120} <S60600>
4978**
4979** The sqlite3_db_handle interface returns the [database connection] handle
4980** to which a [prepared statement] belongs.  The database handle returned by
4981** sqlite3_db_handle is the same database handle that was the first argument
4982** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
4983** create the statement in the first place.
4984**
4985** INVARIANTS:
4986**
4987** {H13123} The [sqlite3_db_handle(S)] interface returns a pointer
4988**          to the [database connection] associated with the
4989**          [prepared statement] S.
4990*/
4991sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
4992
4993/*
4994** CAPI3REF: Find the next prepared statement {H13140} <S60600>
4995**
4996** This interface returns a pointer to the next [prepared statement] after
4997** pStmt associated with the [database connection] pDb.  If pStmt is NULL
4998** then this interface returns a pointer to the first prepared statement
4999** associated with the database connection pDb.  If no prepared statement
5000** satisfies the conditions of this routine, it returns NULL.
5001**
5002** INVARIANTS:
5003**
5004** {H13143} If D is a [database connection] that holds one or more
5005**          unfinalized [prepared statements] and S is a NULL pointer,
5006**          then [sqlite3_next_stmt(D, S)] routine shall return a pointer
5007**          to one of the prepared statements associated with D.
5008**
5009** {H13146} If D is a [database connection] that holds no unfinalized
5010**          [prepared statements] and S is a NULL pointer, then
5011**          [sqlite3_next_stmt(D, S)] routine shall return a NULL pointer.
5012**
5013** {H13149} If S is a [prepared statement] in the [database connection] D
5014**          and S is not the last prepared statement in D, then
5015**          [sqlite3_next_stmt(D, S)] routine shall return a pointer
5016**          to the next prepared statement in D after S.
5017**
5018** {H13152} If S is the last [prepared statement] in the
5019**          [database connection] D then the [sqlite3_next_stmt(D, S)]
5020**          routine shall return a NULL pointer.
5021**
5022** ASSUMPTIONS:
5023**
5024** {A13154} The [database connection] pointer D in a call to
5025**          [sqlite3_next_stmt(D,S)] must refer to an open database
5026**          connection and in particular must not be a NULL pointer.
5027*/
5028sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
5029
5030/*
5031** CAPI3REF: Commit And Rollback Notification Callbacks {H12950} <S60400>
5032**
5033** The sqlite3_commit_hook() interface registers a callback
5034** function to be invoked whenever a transaction is committed.
5035** Any callback set by a previous call to sqlite3_commit_hook()
5036** for the same database connection is overridden.
5037** The sqlite3_rollback_hook() interface registers a callback
5038** function to be invoked whenever a transaction is committed.
5039** Any callback set by a previous call to sqlite3_commit_hook()
5040** for the same database connection is overridden.
5041** The pArg argument is passed through to the callback.
5042** If the callback on a commit hook function returns non-zero,
5043** then the commit is converted into a rollback.
5044**
5045** If another function was previously registered, its
5046** pArg value is returned.  Otherwise NULL is returned.
5047**
5048** The callback implementation must not do anything that will modify
5049** the database connection that invoked the callback.  Any actions
5050** to modify the database connection must be deferred until after the
5051** completion of the [sqlite3_step()] call that triggered the commit
5052** or rollback hook in the first place.
5053** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
5054** database connections for the meaning of "modify" in this paragraph.
5055**
5056** Registering a NULL function disables the callback.
5057**
5058** For the purposes of this API, a transaction is said to have been
5059** rolled back if an explicit "ROLLBACK" statement is executed, or
5060** an error or constraint causes an implicit rollback to occur.
5061** The rollback callback is not invoked if a transaction is
5062** automatically rolled back because the database connection is closed.
5063** The rollback callback is not invoked if a transaction is
5064** rolled back because a commit callback returned non-zero.
5065** <todo> Check on this </todo>
5066**
5067** INVARIANTS:
5068**
5069** {H12951} The [sqlite3_commit_hook(D,F,P)] interface registers the
5070**          callback function F to be invoked with argument P whenever
5071**          a transaction commits on the [database connection] D.
5072**
5073** {H12952} The [sqlite3_commit_hook(D,F,P)] interface returns the P argument
5074**          from the previous call with the same [database connection] D,
5075**          or NULL on the first call for a particular database connection D.
5076**
5077** {H12953} Each call to [sqlite3_commit_hook()] overwrites the callback
5078**          registered by prior calls.
5079**
5080** {H12954} If the F argument to [sqlite3_commit_hook(D,F,P)] is NULL
5081**          then the commit hook callback is canceled and no callback
5082**          is invoked when a transaction commits.
5083**
5084** {H12955} If the commit callback returns non-zero then the commit is
5085**          converted into a rollback.
5086**
5087** {H12961} The [sqlite3_rollback_hook(D,F,P)] interface registers the
5088**          callback function F to be invoked with argument P whenever
5089**          a transaction rolls back on the [database connection] D.
5090**
5091** {H12962} The [sqlite3_rollback_hook(D,F,P)] interface returns the P
5092**          argument from the previous call with the same
5093**          [database connection] D, or NULL on the first call
5094**          for a particular database connection D.
5095**
5096** {H12963} Each call to [sqlite3_rollback_hook()] overwrites the callback
5097**          registered by prior calls.
5098**
5099** {H12964} If the F argument to [sqlite3_rollback_hook(D,F,P)] is NULL
5100**          then the rollback hook callback is canceled and no callback
5101**          is invoked when a transaction rolls back.
5102*/
5103void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
5104void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
5105
5106/*
5107** CAPI3REF: Data Change Notification Callbacks {H12970} <S60400>
5108**
5109** The sqlite3_update_hook() interface registers a callback function
5110** with the [database connection] identified by the first argument
5111** to be invoked whenever a row is updated, inserted or deleted.
5112** Any callback set by a previous call to this function
5113** for the same database connection is overridden.
5114**
5115** The second argument is a pointer to the function to invoke when a
5116** row is updated, inserted or deleted.
5117** The first argument to the callback is a copy of the third argument
5118** to sqlite3_update_hook().
5119** The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
5120** or [SQLITE_UPDATE], depending on the operation that caused the callback
5121** to be invoked.
5122** The third and fourth arguments to the callback contain pointers to the
5123** database and table name containing the affected row.
5124** The final callback parameter is the [rowid] of the row.
5125** In the case of an update, this is the [rowid] after the update takes place.
5126**
5127** The update hook is not invoked when internal system tables are
5128** modified (i.e. sqlite_master and sqlite_sequence).
5129**
5130** The update hook implementation must not do anything that will modify
5131** the database connection that invoked the update hook.  Any actions
5132** to modify the database connection must be deferred until after the
5133** completion of the [sqlite3_step()] call that triggered the update hook.
5134** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
5135** database connections for the meaning of "modify" in this paragraph.
5136**
5137** If another function was previously registered, its pArg value
5138** is returned.  Otherwise NULL is returned.
5139**
5140** INVARIANTS:
5141**
5142** {H12971} The [sqlite3_update_hook(D,F,P)] interface causes the callback
5143**          function F to be invoked with first parameter P whenever
5144**          a table row is modified, inserted, or deleted on
5145**          the [database connection] D.
5146**
5147** {H12973} The [sqlite3_update_hook(D,F,P)] interface returns the value
5148**          of P for the previous call on the same [database connection] D,
5149**          or NULL for the first call.
5150**
5151** {H12975} If the update hook callback F in [sqlite3_update_hook(D,F,P)]
5152**          is NULL then the no update callbacks are made.
5153**
5154** {H12977} Each call to [sqlite3_update_hook(D,F,P)] overrides prior calls
5155**          to the same interface on the same [database connection] D.
5156**
5157** {H12979} The update hook callback is not invoked when internal system
5158**          tables such as sqlite_master and sqlite_sequence are modified.
5159**
5160** {H12981} The second parameter to the update callback
5161**          is one of [SQLITE_INSERT], [SQLITE_DELETE] or [SQLITE_UPDATE],
5162**          depending on the operation that caused the callback to be invoked.
5163**
5164** {H12983} The third and fourth arguments to the callback contain pointers
5165**          to zero-terminated UTF-8 strings which are the names of the
5166**          database and table that is being updated.
5167
5168** {H12985} The final callback parameter is the [rowid] of the row after
5169**          the change occurs.
5170*/
5171void *sqlite3_update_hook(
5172  sqlite3*,
5173  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
5174  void*
5175);
5176
5177/*
5178** CAPI3REF: Enable Or Disable Shared Pager Cache {H10330} <S30900>
5179** KEYWORDS: {shared cache} {shared cache mode}
5180**
5181** This routine enables or disables the sharing of the database cache
5182** and schema data structures between [database connection | connections]
5183** to the same database. Sharing is enabled if the argument is true
5184** and disabled if the argument is false.
5185**
5186** Cache sharing is enabled and disabled for an entire process. {END}
5187** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
5188** sharing was enabled or disabled for each thread separately.
5189**
5190** The cache sharing mode set by this interface effects all subsequent
5191** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
5192** Existing database connections continue use the sharing mode
5193** that was in effect at the time they were opened.
5194**
5195** Virtual tables cannot be used with a shared cache.  When shared
5196** cache is enabled, the [sqlite3_create_module()] API used to register
5197** virtual tables will always return an error.
5198**
5199** This routine returns [SQLITE_OK] if shared cache was enabled or disabled
5200** successfully.  An [error code] is returned otherwise.
5201**
5202** Shared cache is disabled by default. But this might change in
5203** future releases of SQLite.  Applications that care about shared
5204** cache setting should set it explicitly.
5205**
5206** INVARIANTS:
5207**
5208** {H10331} A successful invocation of [sqlite3_enable_shared_cache(B)]
5209**          will enable or disable shared cache mode for any subsequently
5210**          created [database connection] in the same process.
5211**
5212** {H10336} When shared cache is enabled, the [sqlite3_create_module()]
5213**          interface will always return an error.
5214**
5215** {H10337} The [sqlite3_enable_shared_cache(B)] interface returns
5216**          [SQLITE_OK] if shared cache was enabled or disabled successfully.
5217**
5218** {H10339} Shared cache is disabled by default.
5219*/
5220int sqlite3_enable_shared_cache(int);
5221
5222/*
5223** CAPI3REF: Attempt To Free Heap Memory {H17340} <S30220>
5224**
5225** The sqlite3_release_memory() interface attempts to free N bytes
5226** of heap memory by deallocating non-essential memory allocations
5227** held by the database library. {END}  Memory used to cache database
5228** pages to improve performance is an example of non-essential memory.
5229** sqlite3_release_memory() returns the number of bytes actually freed,
5230** which might be more or less than the amount requested.
5231**
5232** INVARIANTS:
5233**
5234** {H17341} The [sqlite3_release_memory(N)] interface attempts to
5235**          free N bytes of heap memory by deallocating non-essential
5236**          memory allocations held by the database library.
5237**
5238** {H16342} The [sqlite3_release_memory(N)] returns the number
5239**          of bytes actually freed, which might be more or less
5240**          than the amount requested.
5241*/
5242int sqlite3_release_memory(int);
5243
5244/*
5245** CAPI3REF: Impose A Limit On Heap Size {H17350} <S30220>
5246**
5247** The sqlite3_soft_heap_limit() interface places a "soft" limit
5248** on the amount of heap memory that may be allocated by SQLite.
5249** If an internal allocation is requested that would exceed the
5250** soft heap limit, [sqlite3_release_memory()] is invoked one or
5251** more times to free up some space before the allocation is performed.
5252**
5253** The limit is called "soft", because if [sqlite3_release_memory()]
5254** cannot free sufficient memory to prevent the limit from being exceeded,
5255** the memory is allocated anyway and the current operation proceeds.
5256**
5257** A negative or zero value for N means that there is no soft heap limit and
5258** [sqlite3_release_memory()] will only be called when memory is exhausted.
5259** The default value for the soft heap limit is zero.
5260**
5261** SQLite makes a best effort to honor the soft heap limit.
5262** But if the soft heap limit cannot be honored, execution will
5263** continue without error or notification.  This is why the limit is
5264** called a "soft" limit.  It is advisory only.
5265**
5266** Prior to SQLite version 3.5.0, this routine only constrained the memory
5267** allocated by a single thread - the same thread in which this routine
5268** runs.  Beginning with SQLite version 3.5.0, the soft heap limit is
5269** applied to all threads. The value specified for the soft heap limit
5270** is an upper bound on the total memory allocation for all threads. In
5271** version 3.5.0 there is no mechanism for limiting the heap usage for
5272** individual threads.
5273**
5274** INVARIANTS:
5275**
5276** {H16351} The [sqlite3_soft_heap_limit(N)] interface places a soft limit
5277**          of N bytes on the amount of heap memory that may be allocated
5278**          using [sqlite3_malloc()] or [sqlite3_realloc()] at any point
5279**          in time.
5280**
5281** {H16352} If a call to [sqlite3_malloc()] or [sqlite3_realloc()] would
5282**          cause the total amount of allocated memory to exceed the
5283**          soft heap limit, then [sqlite3_release_memory()] is invoked
5284**          in an attempt to reduce the memory usage prior to proceeding
5285**          with the memory allocation attempt.
5286**
5287** {H16353} Calls to [sqlite3_malloc()] or [sqlite3_realloc()] that trigger
5288**          attempts to reduce memory usage through the soft heap limit
5289**          mechanism continue even if the attempt to reduce memory
5290**          usage is unsuccessful.
5291**
5292** {H16354} A negative or zero value for N in a call to
5293**          [sqlite3_soft_heap_limit(N)] means that there is no soft
5294**          heap limit and [sqlite3_release_memory()] will only be
5295**          called when memory is completely exhausted.
5296**
5297** {H16355} The default value for the soft heap limit is zero.
5298**
5299** {H16358} Each call to [sqlite3_soft_heap_limit(N)] overrides the
5300**          values set by all prior calls.
5301*/
5302void sqlite3_soft_heap_limit(int);
5303
5304/*
5305** CAPI3REF: Extract Metadata About A Column Of A Table {H12850} <S60300>
5306**
5307** This routine returns metadata about a specific column of a specific
5308** database table accessible using the [database connection] handle
5309** passed as the first function argument.
5310**
5311** The column is identified by the second, third and fourth parameters to
5312** this function. The second parameter is either the name of the database
5313** (i.e. "main", "temp" or an attached database) containing the specified
5314** table or NULL. If it is NULL, then all attached databases are searched
5315** for the table using the same algorithm used by the database engine to
5316** resolve unqualified table references.
5317**
5318** The third and fourth parameters to this function are the table and column
5319** name of the desired column, respectively. Neither of these parameters
5320** may be NULL.
5321**
5322** Metadata is returned by writing to the memory locations passed as the 5th
5323** and subsequent parameters to this function. Any of these arguments may be
5324** NULL, in which case the corresponding element of metadata is omitted.
5325**
5326** <blockquote>
5327** <table border="1">
5328** <tr><th> Parameter <th> Output<br>Type <th>  Description
5329**
5330** <tr><td> 5th <td> const char* <td> Data type
5331** <tr><td> 6th <td> const char* <td> Name of default collation sequence
5332** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
5333** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
5334** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
5335** </table>
5336** </blockquote>
5337**
5338** The memory pointed to by the character pointers returned for the
5339** declaration type and collation sequence is valid only until the next
5340** call to any SQLite API function.
5341**
5342** If the specified table is actually a view, an [error code] is returned.
5343**
5344** If the specified column is "rowid", "oid" or "_rowid_" and an
5345** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
5346** parameters are set for the explicitly declared column. If there is no
5347** explicitly declared [INTEGER PRIMARY KEY] column, then the output
5348** parameters are set as follows:
5349**
5350** <pre>
5351**     data type: "INTEGER"
5352**     collation sequence: "BINARY"
5353**     not null: 0
5354**     primary key: 1
5355**     auto increment: 0
5356** </pre>
5357**
5358** This function may load one or more schemas from database files. If an
5359** error occurs during this process, or if the requested table or column
5360** cannot be found, an [error code] is returned and an error message left
5361** in the [database connection] (to be retrieved using sqlite3_errmsg()).
5362**
5363** This API is only available if the library was compiled with the
5364** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
5365*/
5366int sqlite3_table_column_metadata(
5367  sqlite3 *db,                /* Connection handle */
5368  const char *zDbName,        /* Database name or NULL */
5369  const char *zTableName,     /* Table name */
5370  const char *zColumnName,    /* Column name */
5371  char const **pzDataType,    /* OUTPUT: Declared data type */
5372  char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
5373  int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
5374  int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
5375  int *pAutoinc               /* OUTPUT: True if column is auto-increment */
5376);
5377
5378/*
5379** CAPI3REF: Load An Extension {H12600} <S20500>
5380**
5381** This interface loads an SQLite extension library from the named file.
5382**
5383** {H12601} The sqlite3_load_extension() interface attempts to load an
5384**          SQLite extension library contained in the file zFile.
5385**
5386** {H12602} The entry point is zProc.
5387**
5388** {H12603} zProc may be 0, in which case the name of the entry point
5389**          defaults to "sqlite3_extension_init".
5390**
5391** {H12604} The sqlite3_load_extension() interface shall return
5392**          [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
5393**
5394** {H12605} If an error occurs and pzErrMsg is not 0, then the
5395**          [sqlite3_load_extension()] interface shall attempt to
5396**          fill *pzErrMsg with error message text stored in memory
5397**          obtained from [sqlite3_malloc()]. {END}  The calling function
5398**          should free this memory by calling [sqlite3_free()].
5399**
5400** {H12606} Extension loading must be enabled using
5401**          [sqlite3_enable_load_extension()] prior to calling this API,
5402**          otherwise an error will be returned.
5403*/
5404int sqlite3_load_extension(
5405  sqlite3 *db,          /* Load the extension into this database connection */
5406  const char *zFile,    /* Name of the shared library containing extension */
5407  const char *zProc,    /* Entry point.  Derived from zFile if 0 */
5408  char **pzErrMsg       /* Put error message here if not 0 */
5409);
5410
5411/*
5412** CAPI3REF: Enable Or Disable Extension Loading {H12620} <S20500>
5413**
5414** So as not to open security holes in older applications that are
5415** unprepared to deal with extension loading, and as a means of disabling
5416** extension loading while evaluating user-entered SQL, the following API
5417** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
5418**
5419** Extension loading is off by default. See ticket #1863.
5420**
5421** {H12621} Call the sqlite3_enable_load_extension() routine with onoff==1
5422**          to turn extension loading on and call it with onoff==0 to turn
5423**          it back off again.
5424**
5425** {H12622} Extension loading is off by default.
5426*/
5427int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
5428
5429/*
5430** CAPI3REF: Automatically Load An Extensions {H12640} <S20500>
5431**
5432** This API can be invoked at program startup in order to register
5433** one or more statically linked extensions that will be available
5434** to all new [database connections]. {END}
5435**
5436** This routine stores a pointer to the extension in an array that is
5437** obtained from [sqlite3_malloc()].  If you run a memory leak checker
5438** on your program and it reports a leak because of this array, invoke
5439** [sqlite3_reset_auto_extension()] prior to shutdown to free the memory.
5440**
5441** {H12641} This function registers an extension entry point that is
5442**          automatically invoked whenever a new [database connection]
5443**          is opened using [sqlite3_open()], [sqlite3_open16()],
5444**          or [sqlite3_open_v2()].
5445**
5446** {H12642} Duplicate extensions are detected so calling this routine
5447**          multiple times with the same extension is harmless.
5448**
5449** {H12643} This routine stores a pointer to the extension in an array
5450**          that is obtained from [sqlite3_malloc()].
5451**
5452** {H12644} Automatic extensions apply across all threads.
5453*/
5454int sqlite3_auto_extension(void (*xEntryPoint)(void));
5455
5456/*
5457** CAPI3REF: Reset Automatic Extension Loading {H12660} <S20500>
5458**
5459** This function disables all previously registered automatic
5460** extensions. {END}  It undoes the effect of all prior
5461** [sqlite3_auto_extension()] calls.
5462**
5463** {H12661} This function disables all previously registered
5464**          automatic extensions.
5465**
5466** {H12662} This function disables automatic extensions in all threads.
5467*/
5468void sqlite3_reset_auto_extension(void);
5469
5470/*
5471****** EXPERIMENTAL - subject to change without notice **************
5472**
5473** The interface to the virtual-table mechanism is currently considered
5474** to be experimental.  The interface might change in incompatible ways.
5475** If this is a problem for you, do not use the interface at this time.
5476**
5477** When the virtual-table mechanism stabilizes, we will declare the
5478** interface fixed, support it indefinitely, and remove this comment.
5479*/
5480
5481/*
5482** Structures used by the virtual table interface
5483*/
5484typedef struct sqlite3_vtab sqlite3_vtab;
5485typedef struct sqlite3_index_info sqlite3_index_info;
5486typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
5487typedef struct sqlite3_module sqlite3_module;
5488
5489/*
5490** CAPI3REF: Virtual Table Object {H18000} <S20400>
5491** KEYWORDS: sqlite3_module
5492** EXPERIMENTAL
5493**
5494** A module is a class of virtual tables.  Each module is defined
5495** by an instance of the following structure.  This structure consists
5496** mostly of methods for the module.
5497**
5498** This interface is experimental and is subject to change or
5499** removal in future releases of SQLite.
5500*/
5501struct sqlite3_module {
5502  int iVersion;
5503  int (*xCreate)(sqlite3*, void *pAux,
5504               int argc, const char *const*argv,
5505               sqlite3_vtab **ppVTab, char**);
5506  int (*xConnect)(sqlite3*, void *pAux,
5507               int argc, const char *const*argv,
5508               sqlite3_vtab **ppVTab, char**);
5509  int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
5510  int (*xDisconnect)(sqlite3_vtab *pVTab);
5511  int (*xDestroy)(sqlite3_vtab *pVTab);
5512  int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
5513  int (*xClose)(sqlite3_vtab_cursor*);
5514  int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
5515                int argc, sqlite3_value **argv);
5516  int (*xNext)(sqlite3_vtab_cursor*);
5517  int (*xEof)(sqlite3_vtab_cursor*);
5518  int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
5519  int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
5520  int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
5521  int (*xBegin)(sqlite3_vtab *pVTab);
5522  int (*xSync)(sqlite3_vtab *pVTab);
5523  int (*xCommit)(sqlite3_vtab *pVTab);
5524  int (*xRollback)(sqlite3_vtab *pVTab);
5525  int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
5526                       void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
5527                       void **ppArg);
5528  int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
5529};
5530
5531/*
5532** CAPI3REF: Virtual Table Indexing Information {H18100} <S20400>
5533** KEYWORDS: sqlite3_index_info
5534** EXPERIMENTAL
5535**
5536** The sqlite3_index_info structure and its substructures is used to
5537** pass information into and receive the reply from the xBestIndex
5538** method of an sqlite3_module.  The fields under **Inputs** are the
5539** inputs to xBestIndex and are read-only.  xBestIndex inserts its
5540** results into the **Outputs** fields.
5541**
5542** The aConstraint[] array records WHERE clause constraints of the form:
5543**
5544** <pre>column OP expr</pre>
5545**
5546** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.  The particular operator is
5547** stored in aConstraint[].op.  The index of the column is stored in
5548** aConstraint[].iColumn.  aConstraint[].usable is TRUE if the
5549** expr on the right-hand side can be evaluated (and thus the constraint
5550** is usable) and false if it cannot.
5551**
5552** The optimizer automatically inverts terms of the form "expr OP column"
5553** and makes other simplifications to the WHERE clause in an attempt to
5554** get as many WHERE clause terms into the form shown above as possible.
5555** The aConstraint[] array only reports WHERE clause terms in the correct
5556** form that refer to the particular virtual table being queried.
5557**
5558** Information about the ORDER BY clause is stored in aOrderBy[].
5559** Each term of aOrderBy records a column of the ORDER BY clause.
5560**
5561** The xBestIndex method must fill aConstraintUsage[] with information
5562** about what parameters to pass to xFilter.  If argvIndex>0 then
5563** the right-hand side of the corresponding aConstraint[] is evaluated
5564** and becomes the argvIndex-th entry in argv.  If aConstraintUsage[].omit
5565** is true, then the constraint is assumed to be fully handled by the
5566** virtual table and is not checked again by SQLite.
5567**
5568** The idxNum and idxPtr values are recorded and passed into xFilter.
5569** sqlite3_free() is used to free idxPtr if needToFreeIdxPtr is true.
5570**
5571** The orderByConsumed means that output from xFilter will occur in
5572** the correct order to satisfy the ORDER BY clause so that no separate
5573** sorting step is required.
5574**
5575** The estimatedCost value is an estimate of the cost of doing the
5576** particular lookup.  A full scan of a table with N entries should have
5577** a cost of N.  A binary search of a table of N entries should have a
5578** cost of approximately log(N).
5579**
5580** This interface is experimental and is subject to change or
5581** removal in future releases of SQLite.
5582*/
5583struct sqlite3_index_info {
5584  /* Inputs */
5585  int nConstraint;           /* Number of entries in aConstraint */
5586  struct sqlite3_index_constraint {
5587     int iColumn;              /* Column on left-hand side of constraint */
5588     unsigned char op;         /* Constraint operator */
5589     unsigned char usable;     /* True if this constraint is usable */
5590     int iTermOffset;          /* Used internally - xBestIndex should ignore */
5591  } *aConstraint;            /* Table of WHERE clause constraints */
5592  int nOrderBy;              /* Number of terms in the ORDER BY clause */
5593  struct sqlite3_index_orderby {
5594     int iColumn;              /* Column number */
5595     unsigned char desc;       /* True for DESC.  False for ASC. */
5596  } *aOrderBy;               /* The ORDER BY clause */
5597  /* Outputs */
5598  struct sqlite3_index_constraint_usage {
5599    int argvIndex;           /* if >0, constraint is part of argv to xFilter */
5600    unsigned char omit;      /* Do not code a test for this constraint */
5601  } *aConstraintUsage;
5602  int idxNum;                /* Number used to identify the index */
5603  char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
5604  int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
5605  int orderByConsumed;       /* True if output is already ordered */
5606  double estimatedCost;      /* Estimated cost of using this index */
5607};
5608#define SQLITE_INDEX_CONSTRAINT_EQ    2
5609#define SQLITE_INDEX_CONSTRAINT_GT    4
5610#define SQLITE_INDEX_CONSTRAINT_LE    8
5611#define SQLITE_INDEX_CONSTRAINT_LT    16
5612#define SQLITE_INDEX_CONSTRAINT_GE    32
5613#define SQLITE_INDEX_CONSTRAINT_MATCH 64
5614
5615/*
5616** CAPI3REF: Register A Virtual Table Implementation {H18200} <S20400>
5617** EXPERIMENTAL
5618**
5619** This routine is used to register a new module name with a
5620** [database connection].  Module names must be registered before
5621** creating new virtual tables on the module, or before using
5622** preexisting virtual tables of the module.
5623**
5624** This interface is experimental and is subject to change or
5625** removal in future releases of SQLite.
5626*/
5627SQLITE_EXPERIMENTAL int sqlite3_create_module(
5628  sqlite3 *db,               /* SQLite connection to register module with */
5629  const char *zName,         /* Name of the module */
5630  const sqlite3_module *,    /* Methods for the module */
5631  void *                     /* Client data for xCreate/xConnect */
5632);
5633
5634/*
5635** CAPI3REF: Register A Virtual Table Implementation {H18210} <S20400>
5636** EXPERIMENTAL
5637**
5638** This routine is identical to the [sqlite3_create_module()] method above,
5639** except that it allows a destructor function to be specified. It is
5640** even more experimental than the rest of the virtual tables API.
5641*/
5642SQLITE_EXPERIMENTAL int sqlite3_create_module_v2(
5643  sqlite3 *db,               /* SQLite connection to register module with */
5644  const char *zName,         /* Name of the module */
5645  const sqlite3_module *,    /* Methods for the module */
5646  void *,                    /* Client data for xCreate/xConnect */
5647  void(*xDestroy)(void*)     /* Module destructor function */
5648);
5649
5650/*
5651** CAPI3REF: Virtual Table Instance Object {H18010} <S20400>
5652** KEYWORDS: sqlite3_vtab
5653** EXPERIMENTAL
5654**
5655** Every module implementation uses a subclass of the following structure
5656** to describe a particular instance of the module.  Each subclass will
5657** be tailored to the specific needs of the module implementation.
5658** The purpose of this superclass is to define certain fields that are
5659** common to all module implementations.
5660**
5661** Virtual tables methods can set an error message by assigning a
5662** string obtained from [sqlite3_mprintf()] to zErrMsg.  The method should
5663** take care that any prior string is freed by a call to [sqlite3_free()]
5664** prior to assigning a new string to zErrMsg.  After the error message
5665** is delivered up to the client application, the string will be automatically
5666** freed by sqlite3_free() and the zErrMsg field will be zeroed.  Note
5667** that sqlite3_mprintf() and sqlite3_free() are used on the zErrMsg field
5668** since virtual tables are commonly implemented in loadable extensions which
5669** do not have access to sqlite3MPrintf() or sqlite3Free().
5670**
5671** This interface is experimental and is subject to change or
5672** removal in future releases of SQLite.
5673*/
5674struct sqlite3_vtab {
5675  const sqlite3_module *pModule;  /* The module for this virtual table */
5676  int nRef;                       /* Used internally */
5677  char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
5678  /* Virtual table implementations will typically add additional fields */
5679};
5680
5681/*
5682** CAPI3REF: Virtual Table Cursor Object  {H18020} <S20400>
5683** KEYWORDS: sqlite3_vtab_cursor
5684** EXPERIMENTAL
5685**
5686** Every module implementation uses a subclass of the following structure
5687** to describe cursors that point into the virtual table and are used
5688** to loop through the virtual table.  Cursors are created using the
5689** xOpen method of the module.  Each module implementation will define
5690** the content of a cursor structure to suit its own needs.
5691**
5692** This superclass exists in order to define fields of the cursor that
5693** are common to all implementations.
5694**
5695** This interface is experimental and is subject to change or
5696** removal in future releases of SQLite.
5697*/
5698struct sqlite3_vtab_cursor {
5699  sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
5700  /* Virtual table implementations will typically add additional fields */
5701};
5702
5703/*
5704** CAPI3REF: Declare The Schema Of A Virtual Table {H18280} <S20400>
5705** EXPERIMENTAL
5706**
5707** The xCreate and xConnect methods of a module use the following API
5708** to declare the format (the names and datatypes of the columns) of
5709** the virtual tables they implement.
5710**
5711** This interface is experimental and is subject to change or
5712** removal in future releases of SQLite.
5713*/
5714SQLITE_EXPERIMENTAL int sqlite3_declare_vtab(sqlite3*, const char *zCreateTable);
5715
5716/*
5717** CAPI3REF: Overload A Function For A Virtual Table {H18300} <S20400>
5718** EXPERIMENTAL
5719**
5720** Virtual tables can provide alternative implementations of functions
5721** using the xFindFunction method.  But global versions of those functions
5722** must exist in order to be overloaded.
5723**
5724** This API makes sure a global version of a function with a particular
5725** name and number of parameters exists.  If no such function exists
5726** before this API is called, a new function is created.  The implementation
5727** of the new function always causes an exception to be thrown.  So
5728** the new function is not good for anything by itself.  Its only
5729** purpose is to be a placeholder function that can be overloaded
5730** by virtual tables.
5731**
5732** This API should be considered part of the virtual table interface,
5733** which is experimental and subject to change.
5734*/
5735SQLITE_EXPERIMENTAL int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);
5736
5737/*
5738** The interface to the virtual-table mechanism defined above (back up
5739** to a comment remarkably similar to this one) is currently considered
5740** to be experimental.  The interface might change in incompatible ways.
5741** If this is a problem for you, do not use the interface at this time.
5742**
5743** When the virtual-table mechanism stabilizes, we will declare the
5744** interface fixed, support it indefinitely, and remove this comment.
5745**
5746****** EXPERIMENTAL - subject to change without notice **************
5747*/
5748
5749/*
5750** CAPI3REF: A Handle To An Open BLOB {H17800} <S30230>
5751** KEYWORDS: {BLOB handle} {BLOB handles}
5752**
5753** An instance of this object represents an open BLOB on which
5754** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
5755** Objects of this type are created by [sqlite3_blob_open()]
5756** and destroyed by [sqlite3_blob_close()].
5757** The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
5758** can be used to read or write small subsections of the BLOB.
5759** The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
5760*/
5761typedef struct sqlite3_blob sqlite3_blob;
5762
5763/*
5764** CAPI3REF: Open A BLOB For Incremental I/O {H17810} <S30230>
5765**
5766** This interfaces opens a [BLOB handle | handle] to the BLOB located
5767** in row iRow, column zColumn, table zTable in database zDb;
5768** in other words, the same BLOB that would be selected by:
5769**
5770** <pre>
5771**     SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
5772** </pre> {END}
5773**
5774** If the flags parameter is non-zero, the the BLOB is opened for read
5775** and write access. If it is zero, the BLOB is opened for read access.
5776**
5777** Note that the database name is not the filename that contains
5778** the database but rather the symbolic name of the database that
5779** is assigned when the database is connected using [ATTACH].
5780** For the main database file, the database name is "main".
5781** For TEMP tables, the database name is "temp".
5782**
5783** On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
5784** to *ppBlob. Otherwise an [error code] is returned and any value written
5785** to *ppBlob should not be used by the caller.
5786** This function sets the [database connection] error code and message
5787** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()].
5788**
5789** If the row that a BLOB handle points to is modified by an
5790** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
5791** then the BLOB handle is marked as "expired".
5792** This is true if any column of the row is changed, even a column
5793** other than the one the BLOB handle is open on.
5794** Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
5795** a expired BLOB handle fail with an return code of [SQLITE_ABORT].
5796** Changes written into a BLOB prior to the BLOB expiring are not
5797** rollback by the expiration of the BLOB.  Such changes will eventually
5798** commit if the transaction continues to completion.
5799**
5800** INVARIANTS:
5801**
5802** {H17813} A successful invocation of the [sqlite3_blob_open(D,B,T,C,R,F,P)]
5803**          interface shall open an [sqlite3_blob] object P on the BLOB
5804**          in column C of the table T in the database B on
5805**          the [database connection] D.
5806**
5807** {H17814} A successful invocation of [sqlite3_blob_open(D,...)] shall start
5808**          a new transaction on the [database connection] D if that
5809**          connection is not already in a transaction.
5810**
5811** {H17816} The [sqlite3_blob_open(D,B,T,C,R,F,P)] interface shall open
5812**          the BLOB for read and write access if and only if the F
5813**          parameter is non-zero.
5814**
5815** {H17819} The [sqlite3_blob_open()] interface shall return [SQLITE_OK] on
5816**          success and an appropriate [error code] on failure.
5817**
5818** {H17821} If an error occurs during evaluation of [sqlite3_blob_open(D,...)]
5819**          then subsequent calls to [sqlite3_errcode(D)],
5820**          [sqlite3_extended_errcode()],
5821**          [sqlite3_errmsg(D)], and [sqlite3_errmsg16(D)] shall return
5822**          information appropriate for that error.
5823**
5824** {H17824} If any column in the row that a [sqlite3_blob] has open is
5825**          changed by a separate [UPDATE] or [DELETE] statement or by
5826**          an [ON CONFLICT] side effect, then the [sqlite3_blob] shall
5827**          be marked as invalid.
5828*/
5829int sqlite3_blob_open(
5830  sqlite3*,
5831  const char *zDb,
5832  const char *zTable,
5833  const char *zColumn,
5834  sqlite3_int64 iRow,
5835  int flags,
5836  sqlite3_blob **ppBlob
5837);
5838
5839/*
5840** CAPI3REF: Close A BLOB Handle {H17830} <S30230>
5841**
5842** Closes an open [BLOB handle].
5843**
5844** Closing a BLOB shall cause the current transaction to commit
5845** if there are no other BLOBs, no pending prepared statements, and the
5846** database connection is in [autocommit mode].
5847** If any writes were made to the BLOB, they might be held in cache
5848** until the close operation if they will fit. {END}
5849**
5850** Closing the BLOB often forces the changes
5851** out to disk and so if any I/O errors occur, they will likely occur
5852** at the time when the BLOB is closed.  {H17833} Any errors that occur during
5853** closing are reported as a non-zero return value.
5854**
5855** The BLOB is closed unconditionally.  Even if this routine returns
5856** an error code, the BLOB is still closed.
5857**
5858** INVARIANTS:
5859**
5860** {H17833} The [sqlite3_blob_close(P)] interface closes an [sqlite3_blob]
5861**          object P previously opened using [sqlite3_blob_open()].
5862**
5863** {H17836} Closing an [sqlite3_blob] object using
5864**          [sqlite3_blob_close()] shall cause the current transaction to
5865**          commit if there are no other open [sqlite3_blob] objects
5866**          or [prepared statements] on the same [database connection] and
5867**          the database connection is in [autocommit mode].
5868**
5869** {H17839} The [sqlite3_blob_close(P)] interfaces shall close the
5870**          [sqlite3_blob] object P unconditionally, even if
5871**          [sqlite3_blob_close(P)] returns something other than [SQLITE_OK].
5872*/
5873int sqlite3_blob_close(sqlite3_blob *);
5874
5875/*
5876** CAPI3REF: Return The Size Of An Open BLOB {H17840} <S30230>
5877**
5878** Returns the size in bytes of the BLOB accessible via the open
5879** []BLOB handle] in its only argument.
5880**
5881** INVARIANTS:
5882**
5883** {H17843} The [sqlite3_blob_bytes(P)] interface returns the size
5884**          in bytes of the BLOB that the [sqlite3_blob] object P
5885**          refers to.
5886*/
5887int sqlite3_blob_bytes(sqlite3_blob *);
5888
5889/*
5890** CAPI3REF: Read Data From A BLOB Incrementally {H17850} <S30230>
5891**
5892** This function is used to read data from an open [BLOB handle] into a
5893** caller-supplied buffer. N bytes of data are copied into buffer Z
5894** from the open BLOB, starting at offset iOffset.
5895**
5896** If offset iOffset is less than N bytes from the end of the BLOB,
5897** [SQLITE_ERROR] is returned and no data is read.  If N or iOffset is
5898** less than zero, [SQLITE_ERROR] is returned and no data is read.
5899**
5900** An attempt to read from an expired [BLOB handle] fails with an
5901** error code of [SQLITE_ABORT].
5902**
5903** On success, SQLITE_OK is returned.
5904** Otherwise, an [error code] or an [extended error code] is returned.
5905**
5906** INVARIANTS:
5907**
5908** {H17853} A successful invocation of [sqlite3_blob_read(P,Z,N,X)]
5909**          shall reads N bytes of data out of the BLOB referenced by
5910**          [BLOB handle] P beginning at offset X and store those bytes
5911**          into buffer Z.
5912**
5913** {H17856} In [sqlite3_blob_read(P,Z,N,X)] if the size of the BLOB
5914**          is less than N+X bytes, then the function shall leave the
5915**          Z buffer unchanged and return [SQLITE_ERROR].
5916**
5917** {H17859} In [sqlite3_blob_read(P,Z,N,X)] if X or N is less than zero
5918**          then the function shall leave the Z buffer unchanged
5919**          and return [SQLITE_ERROR].
5920**
5921** {H17862} The [sqlite3_blob_read(P,Z,N,X)] interface shall return [SQLITE_OK]
5922**          if N bytes are successfully read into buffer Z.
5923**
5924** {H17863} If the [BLOB handle] P is expired and X and N are within bounds
5925**          then [sqlite3_blob_read(P,Z,N,X)] shall leave the Z buffer
5926**          unchanged and return [SQLITE_ABORT].
5927**
5928** {H17865} If the requested read could not be completed,
5929**          the [sqlite3_blob_read(P,Z,N,X)] interface shall return an
5930**          appropriate [error code] or [extended error code].
5931**
5932** {H17868} If an error occurs during evaluation of [sqlite3_blob_read(P,...)]
5933**          then subsequent calls to [sqlite3_errcode(D)],
5934**          [sqlite3_extended_errcode()],
5935**          [sqlite3_errmsg(D)], and [sqlite3_errmsg16(D)] shall return
5936**          information appropriate for that error, where D is the
5937**          [database connection] that was used to open the [BLOB handle] P.
5938*/
5939int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);
5940
5941/*
5942** CAPI3REF: Write Data Into A BLOB Incrementally {H17870} <S30230>
5943**
5944** This function is used to write data into an open [BLOB handle] from a
5945** caller-supplied buffer. N bytes of data are copied from the buffer Z
5946** into the open BLOB, starting at offset iOffset.
5947**
5948** If the [BLOB handle] passed as the first argument was not opened for
5949** writing (the flags parameter to [sqlite3_blob_open()] was zero),
5950** this function returns [SQLITE_READONLY].
5951**
5952** This function may only modify the contents of the BLOB; it is
5953** not possible to increase the size of a BLOB using this API.
5954** If offset iOffset is less than N bytes from the end of the BLOB,
5955** [SQLITE_ERROR] is returned and no data is written.  If N is
5956** less than zero [SQLITE_ERROR] is returned and no data is written.
5957**
5958** An attempt to write to an expired [BLOB handle] fails with an
5959** error code of [SQLITE_ABORT].  Writes to the BLOB that occurred
5960** before the [BLOB handle] expired are not rolled back by the
5961** expiration of the handle, though of course those changes might
5962** have been overwritten by the statement that expired the BLOB handle
5963** or by other independent statements.
5964**
5965** On success, SQLITE_OK is returned.
5966** Otherwise, an  [error code] or an [extended error code] is returned.
5967**
5968** INVARIANTS:
5969**
5970** {H17873} A successful invocation of [sqlite3_blob_write(P,Z,N,X)]
5971**          shall write N bytes of data from buffer Z into the BLOB
5972**          referenced by [BLOB handle] P beginning at offset X into
5973**          the BLOB.
5974**
5975** {H17874} In the absence of other overridding changes, the changes
5976**          written to a BLOB by [sqlite3_blob_write()] shall
5977**          remain in effect after the associated [BLOB handle] expires.
5978**
5979** {H17875} If the [BLOB handle] P was opened for reading only then
5980**          an invocation of [sqlite3_blob_write(P,Z,N,X)] shall leave
5981**          the referenced BLOB unchanged and return [SQLITE_READONLY].
5982**
5983** {H17876} If the size of the BLOB referenced by [BLOB handle] P is
5984**          less than N+X bytes then [sqlite3_blob_write(P,Z,N,X)] shall
5985**          leave the BLOB unchanged and return [SQLITE_ERROR].
5986**
5987** {H17877} If the [BLOB handle] P is expired and X and N are within bounds
5988**          then [sqlite3_blob_read(P,Z,N,X)] shall leave the BLOB
5989**          unchanged and return [SQLITE_ABORT].
5990**
5991** {H17879} If X or N are less than zero then [sqlite3_blob_write(P,Z,N,X)]
5992**          shall leave the BLOB referenced by [BLOB handle] P unchanged
5993**          and return [SQLITE_ERROR].
5994**
5995** {H17882} The [sqlite3_blob_write(P,Z,N,X)] interface shall return
5996**          [SQLITE_OK] if N bytes where successfully written into the BLOB.
5997**
5998** {H17885} If the requested write could not be completed,
5999**          the [sqlite3_blob_write(P,Z,N,X)] interface shall return an
6000**          appropriate [error code] or [extended error code].
6001**
6002** {H17888} If an error occurs during evaluation of [sqlite3_blob_write(D,...)]
6003**          then subsequent calls to [sqlite3_errcode(D)],
6004**          [sqlite3_extended_errcode()],
6005**          [sqlite3_errmsg(D)], and [sqlite3_errmsg16(D)] shall return
6006**          information appropriate for that error.
6007*/
6008int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);
6009
6010/*
6011** CAPI3REF: Virtual File System Objects {H11200} <S20100>
6012**
6013** A virtual filesystem (VFS) is an [sqlite3_vfs] object
6014** that SQLite uses to interact
6015** with the underlying operating system.  Most SQLite builds come with a
6016** single default VFS that is appropriate for the host computer.
6017** New VFSes can be registered and existing VFSes can be unregistered.
6018** The following interfaces are provided.
6019**
6020** The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
6021** Names are case sensitive.
6022** Names are zero-terminated UTF-8 strings.
6023** If there is no match, a NULL pointer is returned.
6024** If zVfsName is NULL then the default VFS is returned.
6025**
6026** New VFSes are registered with sqlite3_vfs_register().
6027** Each new VFS becomes the default VFS if the makeDflt flag is set.
6028** The same VFS can be registered multiple times without injury.
6029** To make an existing VFS into the default VFS, register it again
6030** with the makeDflt flag set.  If two different VFSes with the
6031** same name are registered, the behavior is undefined.  If a
6032** VFS is registered with a name that is NULL or an empty string,
6033** then the behavior is undefined.
6034**
6035** Unregister a VFS with the sqlite3_vfs_unregister() interface.
6036** If the default VFS is unregistered, another VFS is chosen as
6037** the default.  The choice for the new VFS is arbitrary.
6038**
6039** INVARIANTS:
6040**
6041** {H11203} The [sqlite3_vfs_find(N)] interface returns a pointer to the
6042**          registered [sqlite3_vfs] object whose name exactly matches
6043**          the zero-terminated UTF-8 string N, or it returns NULL if
6044**          there is no match.
6045**
6046** {H11206} If the N parameter to [sqlite3_vfs_find(N)] is NULL then
6047**          the function returns a pointer to the default [sqlite3_vfs]
6048**          object if there is one, or NULL if there is no default
6049**          [sqlite3_vfs] object.
6050**
6051** {H11209} The [sqlite3_vfs_register(P,F)] interface registers the
6052**          well-formed [sqlite3_vfs] object P using the name given
6053**          by the zName field of the object.
6054**
6055** {H11212} Using the [sqlite3_vfs_register(P,F)] interface to register
6056**          the same [sqlite3_vfs] object multiple times is a harmless no-op.
6057**
6058** {H11215} The [sqlite3_vfs_register(P,F)] interface makes the [sqlite3_vfs]
6059**          object P the default [sqlite3_vfs] object if F is non-zero.
6060**
6061** {H11218} The [sqlite3_vfs_unregister(P)] interface unregisters the
6062**          [sqlite3_vfs] object P so that it is no longer returned by
6063**          subsequent calls to [sqlite3_vfs_find()].
6064*/
6065sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
6066int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
6067int sqlite3_vfs_unregister(sqlite3_vfs*);
6068
6069/*
6070** CAPI3REF: Mutexes {H17000} <S20000>
6071**
6072** The SQLite core uses these routines for thread
6073** synchronization. Though they are intended for internal
6074** use by SQLite, code that links against SQLite is
6075** permitted to use any of these routines.
6076**
6077** The SQLite source code contains multiple implementations
6078** of these mutex routines.  An appropriate implementation
6079** is selected automatically at compile-time.  The following
6080** implementations are available in the SQLite core:
6081**
6082** <ul>
6083** <li>   SQLITE_MUTEX_OS2
6084** <li>   SQLITE_MUTEX_PTHREAD
6085** <li>   SQLITE_MUTEX_W32
6086** <li>   SQLITE_MUTEX_NOOP
6087** </ul>
6088**
6089** The SQLITE_MUTEX_NOOP implementation is a set of routines
6090** that does no real locking and is appropriate for use in
6091** a single-threaded application.  The SQLITE_MUTEX_OS2,
6092** SQLITE_MUTEX_PTHREAD, and SQLITE_MUTEX_W32 implementations
6093** are appropriate for use on OS/2, Unix, and Windows.
6094**
6095** If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
6096** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
6097** implementation is included with the library. In this case the
6098** application must supply a custom mutex implementation using the
6099** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
6100** before calling sqlite3_initialize() or any other public sqlite3_
6101** function that calls sqlite3_initialize().
6102**
6103** {H17011} The sqlite3_mutex_alloc() routine allocates a new
6104** mutex and returns a pointer to it. {H17012} If it returns NULL
6105** that means that a mutex could not be allocated. {H17013} SQLite
6106** will unwind its stack and return an error. {H17014} The argument
6107** to sqlite3_mutex_alloc() is one of these integer constants:
6108**
6109** <ul>
6110** <li>  SQLITE_MUTEX_FAST
6111** <li>  SQLITE_MUTEX_RECURSIVE
6112** <li>  SQLITE_MUTEX_STATIC_MASTER
6113** <li>  SQLITE_MUTEX_STATIC_MEM
6114** <li>  SQLITE_MUTEX_STATIC_MEM2
6115** <li>  SQLITE_MUTEX_STATIC_PRNG
6116** <li>  SQLITE_MUTEX_STATIC_LRU
6117** <li>  SQLITE_MUTEX_STATIC_LRU2
6118** </ul>
6119**
6120** {H17015} The first two constants cause sqlite3_mutex_alloc() to create
6121** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
6122** is used but not necessarily so when SQLITE_MUTEX_FAST is used. {END}
6123** The mutex implementation does not need to make a distinction
6124** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
6125** not want to.  {H17016} But SQLite will only request a recursive mutex in
6126** cases where it really needs one.  {END} If a faster non-recursive mutex
6127** implementation is available on the host platform, the mutex subsystem
6128** might return such a mutex in response to SQLITE_MUTEX_FAST.
6129**
6130** {H17017} The other allowed parameters to sqlite3_mutex_alloc() each return
6131** a pointer to a static preexisting mutex. {END}  Four static mutexes are
6132** used by the current version of SQLite.  Future versions of SQLite
6133** may add additional static mutexes.  Static mutexes are for internal
6134** use by SQLite only.  Applications that use SQLite mutexes should
6135** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
6136** SQLITE_MUTEX_RECURSIVE.
6137**
6138** {H17018} Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
6139** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
6140** returns a different mutex on every call.  {H17034} But for the static
6141** mutex types, the same mutex is returned on every call that has
6142** the same type number.
6143**
6144** {H17019} The sqlite3_mutex_free() routine deallocates a previously
6145** allocated dynamic mutex. {H17020} SQLite is careful to deallocate every
6146** dynamic mutex that it allocates. {A17021} The dynamic mutexes must not be in
6147** use when they are deallocated. {A17022} Attempting to deallocate a static
6148** mutex results in undefined behavior. {H17023} SQLite never deallocates
6149** a static mutex. {END}
6150**
6151** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
6152** to enter a mutex. {H17024} If another thread is already within the mutex,
6153** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
6154** SQLITE_BUSY. {H17025}  The sqlite3_mutex_try() interface returns [SQLITE_OK]
6155** upon successful entry.  {H17026} Mutexes created using
6156** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
6157** {H17027} In such cases the,
6158** mutex must be exited an equal number of times before another thread
6159** can enter.  {A17028} If the same thread tries to enter any other
6160** kind of mutex more than once, the behavior is undefined.
6161** {H17029} SQLite will never exhibit
6162** such behavior in its own use of mutexes.
6163**
6164** Some systems (for example, Windows 95) do not support the operation
6165** implemented by sqlite3_mutex_try().  On those systems, sqlite3_mutex_try()
6166** will always return SQLITE_BUSY.  {H17030} The SQLite core only ever uses
6167** sqlite3_mutex_try() as an optimization so this is acceptable behavior.
6168**
6169** {H17031} The sqlite3_mutex_leave() routine exits a mutex that was
6170** previously entered by the same thread.  {A17032} The behavior
6171** is undefined if the mutex is not currently entered by the
6172** calling thread or is not currently allocated.  {H17033} SQLite will
6173** never do either. {END}
6174**
6175** If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
6176** sqlite3_mutex_leave() is a NULL pointer, then all three routines
6177** behave as no-ops.
6178**
6179** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
6180*/
6181sqlite3_mutex *sqlite3_mutex_alloc(int);
6182void sqlite3_mutex_free(sqlite3_mutex*);
6183void sqlite3_mutex_enter(sqlite3_mutex*);
6184int sqlite3_mutex_try(sqlite3_mutex*);
6185void sqlite3_mutex_leave(sqlite3_mutex*);
6186
6187/*
6188** CAPI3REF: Mutex Methods Object {H17120} <S20130>
6189** EXPERIMENTAL
6190**
6191** An instance of this structure defines the low-level routines
6192** used to allocate and use mutexes.
6193**
6194** Usually, the default mutex implementations provided by SQLite are
6195** sufficient, however the user has the option of substituting a custom
6196** implementation for specialized deployments or systems for which SQLite
6197** does not provide a suitable implementation. In this case, the user
6198** creates and populates an instance of this structure to pass
6199** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.
6200** Additionally, an instance of this structure can be used as an
6201** output variable when querying the system for the current mutex
6202** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.
6203**
6204** The xMutexInit method defined by this structure is invoked as
6205** part of system initialization by the sqlite3_initialize() function.
6206** {H17001} The xMutexInit routine shall be called by SQLite once for each
6207** effective call to [sqlite3_initialize()].
6208**
6209** The xMutexEnd method defined by this structure is invoked as
6210** part of system shutdown by the sqlite3_shutdown() function. The
6211** implementation of this method is expected to release all outstanding
6212** resources obtained by the mutex methods implementation, especially
6213** those obtained by the xMutexInit method. {H17003} The xMutexEnd()
6214** interface shall be invoked once for each call to [sqlite3_shutdown()].
6215**
6216** The remaining seven methods defined by this structure (xMutexAlloc,
6217** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and
6218** xMutexNotheld) implement the following interfaces (respectively):
6219**
6220** <ul>
6221**   <li>  [sqlite3_mutex_alloc()] </li>
6222**   <li>  [sqlite3_mutex_free()] </li>
6223**   <li>  [sqlite3_mutex_enter()] </li>
6224**   <li>  [sqlite3_mutex_try()] </li>
6225**   <li>  [sqlite3_mutex_leave()] </li>
6226**   <li>  [sqlite3_mutex_held()] </li>
6227**   <li>  [sqlite3_mutex_notheld()] </li>
6228** </ul>
6229**
6230** The only difference is that the public sqlite3_XXX functions enumerated
6231** above silently ignore any invocations that pass a NULL pointer instead
6232** of a valid mutex handle. The implementations of the methods defined
6233** by this structure are not required to handle this case, the results
6234** of passing a NULL pointer instead of a valid mutex handle are undefined
6235** (i.e. it is acceptable to provide an implementation that segfaults if
6236** it is passed a NULL pointer).
6237*/
6238typedef struct sqlite3_mutex_methods sqlite3_mutex_methods;
6239struct sqlite3_mutex_methods {
6240  int (*xMutexInit)(void);
6241  int (*xMutexEnd)(void);
6242  sqlite3_mutex *(*xMutexAlloc)(int);
6243  void (*xMutexFree)(sqlite3_mutex *);
6244  void (*xMutexEnter)(sqlite3_mutex *);
6245  int (*xMutexTry)(sqlite3_mutex *);
6246  void (*xMutexLeave)(sqlite3_mutex *);
6247  int (*xMutexHeld)(sqlite3_mutex *);
6248  int (*xMutexNotheld)(sqlite3_mutex *);
6249};
6250
6251/*
6252** CAPI3REF: Mutex Verification Routines {H17080} <S20130> <S30800>
6253**
6254** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
6255** are intended for use inside assert() statements. {H17081} The SQLite core
6256** never uses these routines except inside an assert() and applications
6257** are advised to follow the lead of the core.  {H17082} The core only
6258** provides implementations for these routines when it is compiled
6259** with the SQLITE_DEBUG flag.  {A17087} External mutex implementations
6260** are only required to provide these routines if SQLITE_DEBUG is
6261** defined and if NDEBUG is not defined.
6262**
6263** {H17083} These routines should return true if the mutex in their argument
6264** is held or not held, respectively, by the calling thread.
6265**
6266** {X17084} The implementation is not required to provided versions of these
6267** routines that actually work. If the implementation does not provide working
6268** versions of these routines, it should at least provide stubs that always
6269** return true so that one does not get spurious assertion failures.
6270**
6271** {H17085} If the argument to sqlite3_mutex_held() is a NULL pointer then
6272** the routine should return 1.  {END} This seems counter-intuitive since
6273** clearly the mutex cannot be held if it does not exist.  But the
6274** the reason the mutex does not exist is because the build is not
6275** using mutexes.  And we do not want the assert() containing the
6276** call to sqlite3_mutex_held() to fail, so a non-zero return is
6277** the appropriate thing to do.  {H17086} The sqlite3_mutex_notheld()
6278** interface should also return 1 when given a NULL pointer.
6279*/
6280int sqlite3_mutex_held(sqlite3_mutex*);
6281int sqlite3_mutex_notheld(sqlite3_mutex*);
6282
6283/*
6284** CAPI3REF: Mutex Types {H17001} <H17000>
6285**
6286** The [sqlite3_mutex_alloc()] interface takes a single argument
6287** which is one of these integer constants.
6288**
6289** The set of static mutexes may change from one SQLite release to the
6290** next.  Applications that override the built-in mutex logic must be
6291** prepared to accommodate additional static mutexes.
6292*/
6293#define SQLITE_MUTEX_FAST             0
6294#define SQLITE_MUTEX_RECURSIVE        1
6295#define SQLITE_MUTEX_STATIC_MASTER    2
6296#define SQLITE_MUTEX_STATIC_MEM       3  /* sqlite3_malloc() */
6297#define SQLITE_MUTEX_STATIC_MEM2      4  /* sqlite3_release_memory() */
6298#define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_random() */
6299#define SQLITE_MUTEX_STATIC_LRU       6  /* lru page list */
6300#define SQLITE_MUTEX_STATIC_LRU2      7  /* lru page list */
6301
6302/*
6303** CAPI3REF: Retrieve the mutex for a database connection {H17002} <H17000>
6304**
6305** This interface returns a pointer the [sqlite3_mutex] object that
6306** serializes access to the [database connection] given in the argument
6307** when the [threading mode] is Serialized.
6308** If the [threading mode] is Single-thread or Multi-thread then this
6309** routine returns a NULL pointer.
6310*/
6311sqlite3_mutex *sqlite3_db_mutex(sqlite3*);
6312
6313/*
6314** CAPI3REF: Low-Level Control Of Database Files {H11300} <S30800>
6315**
6316** {H11301} The [sqlite3_file_control()] interface makes a direct call to the
6317** xFileControl method for the [sqlite3_io_methods] object associated
6318** with a particular database identified by the second argument. {H11302} The
6319** name of the database is the name assigned to the database by the
6320** <a href="lang_attach.html">ATTACH</a> SQL command that opened the
6321** database. {H11303} To control the main database file, use the name "main"
6322** or a NULL pointer. {H11304} The third and fourth parameters to this routine
6323** are passed directly through to the second and third parameters of
6324** the xFileControl method.  {H11305} The return value of the xFileControl
6325** method becomes the return value of this routine.
6326**
6327** {H11306} If the second parameter (zDbName) does not match the name of any
6328** open database file, then SQLITE_ERROR is returned. {H11307} This error
6329** code is not remembered and will not be recalled by [sqlite3_errcode()]
6330** or [sqlite3_errmsg()]. {A11308} The underlying xFileControl method might
6331** also return SQLITE_ERROR.  {A11309} There is no way to distinguish between
6332** an incorrect zDbName and an SQLITE_ERROR return from the underlying
6333** xFileControl method. {END}
6334**
6335** See also: [SQLITE_FCNTL_LOCKSTATE]
6336*/
6337int sqlite3_file_control(sqlite3*, const char *zDbName, int op, void*);
6338
6339/*
6340** CAPI3REF: Testing Interface {H11400} <S30800>
6341**
6342** The sqlite3_test_control() interface is used to read out internal
6343** state of SQLite and to inject faults into SQLite for testing
6344** purposes.  The first parameter is an operation code that determines
6345** the number, meaning, and operation of all subsequent parameters.
6346**
6347** This interface is not for use by applications.  It exists solely
6348** for verifying the correct operation of the SQLite library.  Depending
6349** on how the SQLite library is compiled, this interface might not exist.
6350**
6351** The details of the operation codes, their meanings, the parameters
6352** they take, and what they do are all subject to change without notice.
6353** Unlike most of the SQLite API, this function is not guaranteed to
6354** operate consistently from one release to the next.
6355*/
6356int sqlite3_test_control(int op, ...);
6357
6358/*
6359** CAPI3REF: Testing Interface Operation Codes {H11410} <H11400>
6360**
6361** These constants are the valid operation code parameters used
6362** as the first argument to [sqlite3_test_control()].
6363**
6364** These parameters and their meanings are subject to change
6365** without notice.  These values are for testing purposes only.
6366** Applications should not use any of these parameters or the
6367** [sqlite3_test_control()] interface.
6368*/
6369#define SQLITE_TESTCTRL_PRNG_SAVE                5
6370#define SQLITE_TESTCTRL_PRNG_RESTORE             6
6371#define SQLITE_TESTCTRL_PRNG_RESET               7
6372#define SQLITE_TESTCTRL_BITVEC_TEST              8
6373#define SQLITE_TESTCTRL_FAULT_INSTALL            9
6374#define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS     10
6375
6376/*
6377** CAPI3REF: SQLite Runtime Status {H17200} <S60200>
6378** EXPERIMENTAL
6379**
6380** This interface is used to retrieve runtime status information
6381** about the preformance of SQLite, and optionally to reset various
6382** highwater marks.  The first argument is an integer code for
6383** the specific parameter to measure.  Recognized integer codes
6384** are of the form [SQLITE_STATUS_MEMORY_USED | SQLITE_STATUS_...].
6385** The current value of the parameter is returned into *pCurrent.
6386** The highest recorded value is returned in *pHighwater.  If the
6387** resetFlag is true, then the highest record value is reset after
6388** *pHighwater is written. Some parameters do not record the highest
6389** value.  For those parameters
6390** nothing is written into *pHighwater and the resetFlag is ignored.
6391** Other parameters record only the highwater mark and not the current
6392** value.  For these latter parameters nothing is written into *pCurrent.
6393**
6394** This routine returns SQLITE_OK on success and a non-zero
6395** [error code] on failure.
6396**
6397** This routine is threadsafe but is not atomic.  This routine can
6398** called while other threads are running the same or different SQLite
6399** interfaces.  However the values returned in *pCurrent and
6400** *pHighwater reflect the status of SQLite at different points in time
6401** and it is possible that another thread might change the parameter
6402** in between the times when *pCurrent and *pHighwater are written.
6403**
6404** See also: [sqlite3_db_status()]
6405*/
6406SQLITE_EXPERIMENTAL int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag);
6407
6408
6409/*
6410** CAPI3REF: Status Parameters {H17250} <H17200>
6411** EXPERIMENTAL
6412**
6413** These integer constants designate various run-time status parameters
6414** that can be returned by [sqlite3_status()].
6415**
6416** <dl>
6417** <dt>SQLITE_STATUS_MEMORY_USED</dt>
6418** <dd>This parameter is the current amount of memory checked out
6419** using [sqlite3_malloc()], either directly or indirectly.  The
6420** figure includes calls made to [sqlite3_malloc()] by the application
6421** and internal memory usage by the SQLite library.  Scratch memory
6422** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache
6423** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in
6424** this parameter.  The amount returned is the sum of the allocation
6425** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>
6426**
6427** <dt>SQLITE_STATUS_MALLOC_SIZE</dt>
6428** <dd>This parameter records the largest memory allocation request
6429** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their
6430** internal equivalents).  Only the value returned in the
6431** *pHighwater parameter to [sqlite3_status()] is of interest.
6432** The value written into the *pCurrent parameter is undefined.</dd>
6433**
6434** <dt>SQLITE_STATUS_PAGECACHE_USED</dt>
6435** <dd>This parameter returns the number of pages used out of the
6436** [pagecache memory allocator] that was configured using
6437** [SQLITE_CONFIG_PAGECACHE].  The
6438** value returned is in pages, not in bytes.</dd>
6439**
6440** <dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt>
6441** <dd>This parameter returns the number of bytes of page cache
6442** allocation which could not be statisfied by the [SQLITE_CONFIG_PAGECACHE]
6443** buffer and where forced to overflow to [sqlite3_malloc()].  The
6444** returned value includes allocations that overflowed because they
6445** where too large (they were larger than the "sz" parameter to
6446** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because
6447** no space was left in the page cache.</dd>
6448**
6449** <dt>SQLITE_STATUS_PAGECACHE_SIZE</dt>
6450** <dd>This parameter records the largest memory allocation request
6451** handed to [pagecache memory allocator].  Only the value returned in the
6452** *pHighwater parameter to [sqlite3_status()] is of interest.
6453** The value written into the *pCurrent parameter is undefined.</dd>
6454**
6455** <dt>SQLITE_STATUS_SCRATCH_USED</dt>
6456** <dd>This parameter returns the number of allocations used out of the
6457** [scratch memory allocator] configured using
6458** [SQLITE_CONFIG_SCRATCH].  The value returned is in allocations, not
6459** in bytes.  Since a single thread may only have one scratch allocation
6460** outstanding at time, this parameter also reports the number of threads
6461** using scratch memory at the same time.</dd>
6462**
6463** <dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt>
6464** <dd>This parameter returns the number of bytes of scratch memory
6465** allocation which could not be statisfied by the [SQLITE_CONFIG_SCRATCH]
6466** buffer and where forced to overflow to [sqlite3_malloc()].  The values
6467** returned include overflows because the requested allocation was too
6468** larger (that is, because the requested allocation was larger than the
6469** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer
6470** slots were available.
6471** </dd>
6472**
6473** <dt>SQLITE_STATUS_SCRATCH_SIZE</dt>
6474** <dd>This parameter records the largest memory allocation request
6475** handed to [scratch memory allocator].  Only the value returned in the
6476** *pHighwater parameter to [sqlite3_status()] is of interest.
6477** The value written into the *pCurrent parameter is undefined.</dd>
6478**
6479** <dt>SQLITE_STATUS_PARSER_STACK</dt>
6480** <dd>This parameter records the deepest parser stack.  It is only
6481** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>
6482** </dl>
6483**
6484** New status parameters may be added from time to time.
6485*/
6486#define SQLITE_STATUS_MEMORY_USED          0
6487#define SQLITE_STATUS_PAGECACHE_USED       1
6488#define SQLITE_STATUS_PAGECACHE_OVERFLOW   2
6489#define SQLITE_STATUS_SCRATCH_USED         3
6490#define SQLITE_STATUS_SCRATCH_OVERFLOW     4
6491#define SQLITE_STATUS_MALLOC_SIZE          5
6492#define SQLITE_STATUS_PARSER_STACK         6
6493#define SQLITE_STATUS_PAGECACHE_SIZE       7
6494#define SQLITE_STATUS_SCRATCH_SIZE         8
6495
6496/*
6497** CAPI3REF: Database Connection Status {H17500} <S60200>
6498** EXPERIMENTAL
6499**
6500** This interface is used to retrieve runtime status information
6501** about a single [database connection].  The first argument is the
6502** database connection object to be interrogated.  The second argument
6503** is the parameter to interrogate.  Currently, the only allowed value
6504** for the second parameter is [SQLITE_DBSTATUS_LOOKASIDE_USED].
6505** Additional options will likely appear in future releases of SQLite.
6506**
6507** The current value of the requested parameter is written into *pCur
6508** and the highest instantaneous value is written into *pHiwtr.  If
6509** the resetFlg is true, then the highest instantaneous value is
6510** reset back down to the current value.
6511**
6512** See also: [sqlite3_status()] and [sqlite3_stmt_status()].
6513*/
6514SQLITE_EXPERIMENTAL int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);
6515
6516/*
6517** CAPI3REF: Status Parameters for database connections {H17520} <H17500>
6518** EXPERIMENTAL
6519**
6520** Status verbs for [sqlite3_db_status()].
6521**
6522** <dl>
6523** <dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
6524** <dd>This parameter returns the number of lookaside memory slots currently
6525** checked out.</dd>
6526** </dl>
6527*/
6528#define SQLITE_DBSTATUS_LOOKASIDE_USED     0
6529
6530
6531/*
6532** CAPI3REF: Prepared Statement Status {H17550} <S60200>
6533** EXPERIMENTAL
6534**
6535** Each prepared statement maintains various
6536** [SQLITE_STMTSTATUS_SORT | counters] that measure the number
6537** of times it has performed specific operations.  These counters can
6538** be used to monitor the performance characteristics of the prepared
6539** statements.  For example, if the number of table steps greatly exceeds
6540** the number of table searches or result rows, that would tend to indicate
6541** that the prepared statement is using a full table scan rather than
6542** an index.
6543**
6544** This interface is used to retrieve and reset counter values from
6545** a [prepared statement].  The first argument is the prepared statement
6546** object to be interrogated.  The second argument
6547** is an integer code for a specific [SQLITE_STMTSTATUS_SORT | counter]
6548** to be interrogated.
6549** The current value of the requested counter is returned.
6550** If the resetFlg is true, then the counter is reset to zero after this
6551** interface call returns.
6552**
6553** See also: [sqlite3_status()] and [sqlite3_db_status()].
6554*/
6555SQLITE_EXPERIMENTAL int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);
6556
6557/*
6558** CAPI3REF: Status Parameters for prepared statements {H17570} <H17550>
6559** EXPERIMENTAL
6560**
6561** These preprocessor macros define integer codes that name counter
6562** values associated with the [sqlite3_stmt_status()] interface.
6563** The meanings of the various counters are as follows:
6564**
6565** <dl>
6566** <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt>
6567** <dd>This is the number of times that SQLite has stepped forward in
6568** a table as part of a full table scan.  Large numbers for this counter
6569** may indicate opportunities for performance improvement through
6570** careful use of indices.</dd>
6571**
6572** <dt>SQLITE_STMTSTATUS_SORT</dt>
6573** <dd>This is the number of sort operations that have occurred.
6574** A non-zero value in this counter may indicate an opportunity to
6575** improvement performance through careful use of indices.</dd>
6576**
6577** </dl>
6578*/
6579#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
6580#define SQLITE_STMTSTATUS_SORT              2
6581
6582/*
6583** CAPI3REF: Custom Page Cache Object
6584** EXPERIMENTAL
6585**
6586** The sqlite3_pcache type is opaque.  It is implemented by
6587** the pluggable module.  The SQLite core has no knowledge of
6588** its size or internal structure and never deals with the
6589** sqlite3_pcache object except by holding and passing pointers
6590** to the object.
6591**
6592** See [sqlite3_pcache_methods] for additional information.
6593*/
6594typedef struct sqlite3_pcache sqlite3_pcache;
6595
6596/*
6597** CAPI3REF: Application Defined Page Cache.
6598** EXPERIMENTAL
6599**
6600** The [sqlite3_config]([SQLITE_CONFIG_PCACHE], ...) interface can
6601** register an alternative page cache implementation by passing in an
6602** instance of the sqlite3_pcache_methods structure. The majority of the
6603** heap memory used by sqlite is used by the page cache to cache data read
6604** from, or ready to be written to, the database file. By implementing a
6605** custom page cache using this API, an application can control more
6606** precisely the amount of memory consumed by sqlite, the way in which
6607** said memory is allocated and released, and the policies used to
6608** determine exactly which parts of a database file are cached and for
6609** how long.
6610**
6611** The contents of the structure are copied to an internal buffer by sqlite
6612** within the call to [sqlite3_config].
6613**
6614** The xInit() method is called once for each call to [sqlite3_initialize()]
6615** (usually only once during the lifetime of the process). It is passed
6616** a copy of the sqlite3_pcache_methods.pArg value. It can be used to set
6617** up global structures and mutexes required by the custom page cache
6618** implementation. The xShutdown() method is called from within
6619** [sqlite3_shutdown()], if the application invokes this API. It can be used
6620** to clean up any outstanding resources before process shutdown, if required.
6621**
6622** The xCreate() method is used to construct a new cache instance. The
6623** first parameter, szPage, is the size in bytes of the pages that must
6624** be allocated by the cache. szPage will not be a power of two. The
6625** second argument, bPurgeable, is true if the cache being created will
6626** be used to cache database pages read from a file stored on disk, or
6627** false if it is used for an in-memory database. The cache implementation
6628** does not have to do anything special based on the value of bPurgeable,
6629** it is purely advisory.
6630**
6631** The xCachesize() method may be called at any time by SQLite to set the
6632** suggested maximum cache-size (number of pages stored by) the cache
6633** instance passed as the first argument. This is the value configured using
6634** the SQLite "[PRAGMA cache_size]" command. As with the bPurgeable parameter,
6635** the implementation is not required to do anything special with this
6636** value, it is advisory only.
6637**
6638** The xPagecount() method should return the number of pages currently
6639** stored in the cache supplied as an argument.
6640**
6641** The xFetch() method is used to fetch a page and return a pointer to it.
6642** A 'page', in this context, is a buffer of szPage bytes aligned at an
6643** 8-byte boundary. The page to be fetched is determined by the key. The
6644** mimimum key value is 1. After it has been retrieved using xFetch, the page
6645** is considered to be pinned.
6646**
6647** If the requested page is already in the page cache, then a pointer to
6648** the cached buffer should be returned with its contents intact. If the
6649** page is not already in the cache, then the expected behaviour of the
6650** cache is determined by the value of the createFlag parameter passed
6651** to xFetch, according to the following table:
6652**
6653** <table border=1 width=85% align=center>
6654**   <tr><th>createFlag<th>Expected Behaviour
6655**   <tr><td>0<td>NULL should be returned. No new cache entry is created.
6656**   <tr><td>1<td>If createFlag is set to 1, this indicates that
6657**                SQLite is holding pinned pages that can be unpinned
6658**                by writing their contents to the database file (a
6659**                relatively expensive operation). In this situation the
6660**                cache implementation has two choices: it can return NULL,
6661**                in which case SQLite will attempt to unpin one or more
6662**                pages before re-requesting the same page, or it can
6663**                allocate a new page and return a pointer to it. If a new
6664**                page is allocated, then it must be completely zeroed before
6665**                it is returned.
6666**   <tr><td>2<td>If createFlag is set to 2, then SQLite is not holding any
6667**                pinned pages associated with the specific cache passed
6668**                as the first argument to xFetch() that can be unpinned. The
6669**                cache implementation should attempt to allocate a new
6670**                cache entry and return a pointer to it. Again, the new
6671**                page should be zeroed before it is returned. If the xFetch()
6672**                method returns NULL when createFlag==2, SQLite assumes that
6673**                a memory allocation failed and returns SQLITE_NOMEM to the
6674**                user.
6675** </table>
6676**
6677** xUnpin() is called by SQLite with a pointer to a currently pinned page
6678** as its second argument. If the third parameter, discard, is non-zero,
6679** then the page should be evicted from the cache. In this case SQLite
6680** assumes that the next time the page is retrieved from the cache using
6681** the xFetch() method, it will be zeroed. If the discard parameter is
6682** zero, then the page is considered to be unpinned. The cache implementation
6683** may choose to reclaim (free or recycle) unpinned pages at any time.
6684** SQLite assumes that next time the page is retrieved from the cache
6685** it will either be zeroed, or contain the same data that it did when it
6686** was unpinned.
6687**
6688** The cache is not required to perform any reference counting. A single
6689** call to xUnpin() unpins the page regardless of the number of prior calls
6690** to xFetch().
6691**
6692** The xRekey() method is used to change the key value associated with the
6693** page passed as the second argument from oldKey to newKey. If the cache
6694** previously contains an entry associated with newKey, it should be
6695** discarded. Any prior cache entry associated with newKey is guaranteed not
6696** to be pinned.
6697**
6698** When SQLite calls the xTruncate() method, the cache must discard all
6699** existing cache entries with page numbers (keys) greater than or equal
6700** to the value of the iLimit parameter passed to xTruncate(). If any
6701** of these pages are pinned, they are implicitly unpinned, meaning that
6702** they can be safely discarded.
6703**
6704** The xDestroy() method is used to delete a cache allocated by xCreate().
6705** All resources associated with the specified cache should be freed. After
6706** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]
6707** handle invalid, and will not use it with any other sqlite3_pcache_methods
6708** functions.
6709*/
6710typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;
6711struct sqlite3_pcache_methods {
6712  void *pArg;
6713  int (*xInit)(void*);
6714  void (*xShutdown)(void*);
6715  sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable);
6716  void (*xCachesize)(sqlite3_pcache*, int nCachesize);
6717  int (*xPagecount)(sqlite3_pcache*);
6718  void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
6719  void (*xUnpin)(sqlite3_pcache*, void*, int discard);
6720  void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
6721  void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
6722  void (*xDestroy)(sqlite3_pcache*);
6723};
6724
6725/*
6726** Undo the hack that converts floating point types to integer for
6727** builds on processors without floating point support.
6728*/
6729#ifdef SQLITE_OMIT_FLOATING_POINT
6730# undef double
6731#endif
6732
6733#ifdef __cplusplus
6734}  /* End of the 'extern "C"' block */
6735#endif
6736#endif
6737