xref: /sqlite-3.40.0/src/sqliteInt.h (revision 74e4352a)
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 ** Internal interface definitions for SQLite.
13 **
14 ** @(#) $Id: sqliteInt.h,v 1.541 2007/03/02 06:24:19 danielk1977 Exp $
15 */
16 #ifndef _SQLITEINT_H_
17 #define _SQLITEINT_H_
18 
19 /*
20 ** Extra interface definitions for those who need them
21 */
22 #ifdef SQLITE_EXTRA
23 # include "sqliteExtra.h"
24 #endif
25 
26 /*
27 ** Many people are failing to set -DNDEBUG=1 when compiling SQLite.
28 ** Setting NDEBUG makes the code smaller and run faster.  So the following
29 ** lines are added to automatically set NDEBUG unless the -DSQLITE_DEBUG=1
30 ** option is set.  Thus NDEBUG becomes an opt-in rather than an opt-out
31 ** feature.
32 */
33 #if !defined(NDEBUG) && !defined(SQLITE_DEBUG)
34 # define NDEBUG 1
35 #endif
36 
37 /*
38 ** These #defines should enable >2GB file support on Posix if the
39 ** underlying operating system supports it.  If the OS lacks
40 ** large file support, or if the OS is windows, these should be no-ops.
41 **
42 ** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
43 ** on the compiler command line.  This is necessary if you are compiling
44 ** on a recent machine (ex: RedHat 7.2) but you want your code to work
45 ** on an older machine (ex: RedHat 6.0).  If you compile on RedHat 7.2
46 ** without this option, LFS is enable.  But LFS does not exist in the kernel
47 ** in RedHat 6.0, so the code won't work.  Hence, for maximum binary
48 ** portability you should omit LFS.
49 **
50 ** Similar is true for MacOS.  LFS is only supported on MacOS 9 and later.
51 */
52 #ifndef SQLITE_DISABLE_LFS
53 # define _LARGE_FILE       1
54 # ifndef _FILE_OFFSET_BITS
55 #   define _FILE_OFFSET_BITS 64
56 # endif
57 # define _LARGEFILE_SOURCE 1
58 #endif
59 
60 #include "sqlite3.h"
61 #include "hash.h"
62 #include "parse.h"
63 #include <stdio.h>
64 #include <stdlib.h>
65 #include <string.h>
66 #include <assert.h>
67 #include <stddef.h>
68 
69 /*
70 ** If compiling for a processor that lacks floating point support,
71 ** substitute integer for floating-point
72 */
73 #ifdef SQLITE_OMIT_FLOATING_POINT
74 # define double sqlite_int64
75 # define LONGDOUBLE_TYPE sqlite_int64
76 # ifndef SQLITE_BIG_DBL
77 #   define SQLITE_BIG_DBL (0x7fffffffffffffff)
78 # endif
79 # define SQLITE_OMIT_DATETIME_FUNCS 1
80 # define SQLITE_OMIT_TRACE 1
81 #endif
82 #ifndef SQLITE_BIG_DBL
83 # define SQLITE_BIG_DBL (1e99)
84 #endif
85 
86 /*
87 ** The maximum number of in-memory pages to use for the main database
88 ** table and for temporary tables. Internally, the MAX_PAGES and
89 ** TEMP_PAGES macros are used. To override the default values at
90 ** compilation time, the SQLITE_DEFAULT_CACHE_SIZE and
91 ** SQLITE_DEFAULT_TEMP_CACHE_SIZE macros should be set.
92 */
93 #ifdef SQLITE_DEFAULT_CACHE_SIZE
94 # define MAX_PAGES SQLITE_DEFAULT_CACHE_SIZE
95 #else
96 # define MAX_PAGES   2000
97 #endif
98 #ifdef SQLITE_DEFAULT_TEMP_CACHE_SIZE
99 # define TEMP_PAGES SQLITE_DEFAULT_TEMP_CACHE_SIZE
100 #else
101 # define TEMP_PAGES   500
102 #endif
103 
104 /*
105 ** OMIT_TEMPDB is set to 1 if SQLITE_OMIT_TEMPDB is defined, or 0
106 ** afterward. Having this macro allows us to cause the C compiler
107 ** to omit code used by TEMP tables without messy #ifndef statements.
108 */
109 #ifdef SQLITE_OMIT_TEMPDB
110 #define OMIT_TEMPDB 1
111 #else
112 #define OMIT_TEMPDB 0
113 #endif
114 
115 /*
116 ** If the following macro is set to 1, then NULL values are considered
117 ** distinct when determining whether or not two entries are the same
118 ** in a UNIQUE index.  This is the way PostgreSQL, Oracle, DB2, MySQL,
119 ** OCELOT, and Firebird all work.  The SQL92 spec explicitly says this
120 ** is the way things are suppose to work.
121 **
122 ** If the following macro is set to 0, the NULLs are indistinct for
123 ** a UNIQUE index.  In this mode, you can only have a single NULL entry
124 ** for a column declared UNIQUE.  This is the way Informix and SQL Server
125 ** work.
126 */
127 #define NULL_DISTINCT_FOR_UNIQUE 1
128 
129 /*
130 ** The maximum number of attached databases.  This must be at least 2
131 ** in order to support the main database file (0) and the file used to
132 ** hold temporary tables (1).  And it must be less than 32 because
133 ** we use a bitmask of databases with a u32 in places (for example
134 ** the Parse.cookieMask field).
135 */
136 #define MAX_ATTACHED 10
137 
138 /*
139 ** The maximum value of a ?nnn wildcard that the parser will accept.
140 */
141 #define SQLITE_MAX_VARIABLE_NUMBER 999
142 
143 /*
144 ** The "file format" number is an integer that is incremented whenever
145 ** the VDBE-level file format changes.  The following macros define the
146 ** the default file format for new databases and the maximum file format
147 ** that the library can read.
148 */
149 #define SQLITE_MAX_FILE_FORMAT 4
150 #ifndef SQLITE_DEFAULT_FILE_FORMAT
151 # define SQLITE_DEFAULT_FILE_FORMAT 1
152 #endif
153 
154 /*
155 ** Provide a default value for TEMP_STORE in case it is not specified
156 ** on the command-line
157 */
158 #ifndef TEMP_STORE
159 # define TEMP_STORE 1
160 #endif
161 
162 /*
163 ** GCC does not define the offsetof() macro so we'll have to do it
164 ** ourselves.
165 */
166 #ifndef offsetof
167 #define offsetof(STRUCTURE,FIELD) ((int)((char*)&((STRUCTURE*)0)->FIELD))
168 #endif
169 
170 /*
171 ** Check to see if this machine uses EBCDIC.  (Yes, believe it or
172 ** not, there are still machines out there that use EBCDIC.)
173 */
174 #if 'A' == '\301'
175 # define SQLITE_EBCDIC 1
176 #else
177 # define SQLITE_ASCII 1
178 #endif
179 
180 /*
181 ** Integers of known sizes.  These typedefs might change for architectures
182 ** where the sizes very.  Preprocessor macros are available so that the
183 ** types can be conveniently redefined at compile-type.  Like this:
184 **
185 **         cc '-DUINTPTR_TYPE=long long int' ...
186 */
187 #ifndef UINT32_TYPE
188 # define UINT32_TYPE unsigned int
189 #endif
190 #ifndef UINT16_TYPE
191 # define UINT16_TYPE unsigned short int
192 #endif
193 #ifndef INT16_TYPE
194 # define INT16_TYPE short int
195 #endif
196 #ifndef UINT8_TYPE
197 # define UINT8_TYPE unsigned char
198 #endif
199 #ifndef INT8_TYPE
200 # define INT8_TYPE signed char
201 #endif
202 #ifndef LONGDOUBLE_TYPE
203 # define LONGDOUBLE_TYPE long double
204 #endif
205 typedef sqlite_int64 i64;          /* 8-byte signed integer */
206 typedef sqlite_uint64 u64;         /* 8-byte unsigned integer */
207 typedef UINT32_TYPE u32;           /* 4-byte unsigned integer */
208 typedef UINT16_TYPE u16;           /* 2-byte unsigned integer */
209 typedef INT16_TYPE i16;            /* 2-byte signed integer */
210 typedef UINT8_TYPE u8;             /* 1-byte unsigned integer */
211 typedef UINT8_TYPE i8;             /* 1-byte signed integer */
212 
213 /*
214 ** Macros to determine whether the machine is big or little endian,
215 ** evaluated at runtime.
216 */
217 extern const int sqlite3one;
218 #define SQLITE_BIGENDIAN    (*(char *)(&sqlite3one)==0)
219 #define SQLITE_LITTLEENDIAN (*(char *)(&sqlite3one)==1)
220 
221 /*
222 ** An instance of the following structure is used to store the busy-handler
223 ** callback for a given sqlite handle.
224 **
225 ** The sqlite.busyHandler member of the sqlite struct contains the busy
226 ** callback for the database handle. Each pager opened via the sqlite
227 ** handle is passed a pointer to sqlite.busyHandler. The busy-handler
228 ** callback is currently invoked only from within pager.c.
229 */
230 typedef struct BusyHandler BusyHandler;
231 struct BusyHandler {
232   int (*xFunc)(void *,int);  /* The busy callback */
233   void *pArg;                /* First arg to busy callback */
234   int nBusy;                 /* Incremented with each busy call */
235 };
236 
237 /*
238 ** Defer sourcing vdbe.h and btree.h until after the "u8" and
239 ** "BusyHandler typedefs.
240 */
241 #include "vdbe.h"
242 #include "btree.h"
243 #include "pager.h"
244 
245 #ifdef SQLITE_MEMDEBUG
246 /*
247 ** The following global variables are used for testing and debugging
248 ** only.  They only work if SQLITE_MEMDEBUG is defined.
249 */
250 extern int sqlite3_nMalloc;      /* Number of sqliteMalloc() calls */
251 extern int sqlite3_nFree;        /* Number of sqliteFree() calls */
252 extern int sqlite3_iMallocFail;  /* Fail sqliteMalloc() after this many calls */
253 extern int sqlite3_iMallocReset; /* Set iMallocFail to this when it reaches 0 */
254 
255 extern void *sqlite3_pFirst;         /* Pointer to linked list of allocations */
256 extern int sqlite3_nMaxAlloc;        /* High water mark of ThreadData.nAlloc */
257 extern int sqlite3_mallocDisallowed; /* assert() in sqlite3Malloc() if set */
258 extern int sqlite3_isFail;           /* True if all malloc calls should fail */
259 extern const char *sqlite3_zFile;    /* Filename to associate debug info with */
260 extern int sqlite3_iLine;            /* Line number for debug info */
261 
262 #define ENTER_MALLOC (sqlite3_zFile = __FILE__, sqlite3_iLine = __LINE__)
263 #define sqliteMalloc(x)          (ENTER_MALLOC, sqlite3Malloc(x,1))
264 #define sqliteMallocRaw(x)       (ENTER_MALLOC, sqlite3MallocRaw(x,1))
265 #define sqliteRealloc(x,y)       (ENTER_MALLOC, sqlite3Realloc(x,y))
266 #define sqliteStrDup(x)          (ENTER_MALLOC, sqlite3StrDup(x))
267 #define sqliteStrNDup(x,y)       (ENTER_MALLOC, sqlite3StrNDup(x,y))
268 #define sqliteReallocOrFree(x,y) (ENTER_MALLOC, sqlite3ReallocOrFree(x,y))
269 
270 #else
271 
272 #define ENTER_MALLOC 0
273 #define sqliteMalloc(x)          sqlite3Malloc(x,1)
274 #define sqliteMallocRaw(x)       sqlite3MallocRaw(x,1)
275 #define sqliteRealloc(x,y)       sqlite3Realloc(x,y)
276 #define sqliteStrDup(x)          sqlite3StrDup(x)
277 #define sqliteStrNDup(x,y)       sqlite3StrNDup(x,y)
278 #define sqliteReallocOrFree(x,y) sqlite3ReallocOrFree(x,y)
279 
280 #endif
281 
282 #define sqliteFree(x)          sqlite3FreeX(x)
283 #define sqliteAllocSize(x)     sqlite3AllocSize(x)
284 
285 
286 /*
287 ** An instance of this structure might be allocated to store information
288 ** specific to a single thread.
289 */
290 struct ThreadData {
291   int dummy;               /* So that this structure is never empty */
292 
293 #ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
294   int nSoftHeapLimit;      /* Suggested max mem allocation.  No limit if <0 */
295   int nAlloc;              /* Number of bytes currently allocated */
296   Pager *pPager;           /* Linked list of all pagers in this thread */
297 #endif
298 
299 #ifndef SQLITE_OMIT_SHARED_CACHE
300   u8 useSharedData;        /* True if shared pagers and schemas are enabled */
301   BtShared *pBtree;        /* Linked list of all currently open BTrees */
302 #endif
303 };
304 
305 /*
306 ** Name of the master database table.  The master database table
307 ** is a special table that holds the names and attributes of all
308 ** user tables and indices.
309 */
310 #define MASTER_NAME       "sqlite_master"
311 #define TEMP_MASTER_NAME  "sqlite_temp_master"
312 
313 /*
314 ** The root-page of the master database table.
315 */
316 #define MASTER_ROOT       1
317 
318 /*
319 ** The name of the schema table.
320 */
321 #define SCHEMA_TABLE(x)  ((!OMIT_TEMPDB)&&(x==1)?TEMP_MASTER_NAME:MASTER_NAME)
322 
323 /*
324 ** A convenience macro that returns the number of elements in
325 ** an array.
326 */
327 #define ArraySize(X)    (sizeof(X)/sizeof(X[0]))
328 
329 /*
330 ** Forward references to structures
331 */
332 typedef struct AggInfo AggInfo;
333 typedef struct AuthContext AuthContext;
334 typedef struct CollSeq CollSeq;
335 typedef struct Column Column;
336 typedef struct Db Db;
337 typedef struct Schema Schema;
338 typedef struct Expr Expr;
339 typedef struct ExprList ExprList;
340 typedef struct FKey FKey;
341 typedef struct FuncDef FuncDef;
342 typedef struct IdList IdList;
343 typedef struct Index Index;
344 typedef struct KeyClass KeyClass;
345 typedef struct KeyInfo KeyInfo;
346 typedef struct Module Module;
347 typedef struct NameContext NameContext;
348 typedef struct Parse Parse;
349 typedef struct Select Select;
350 typedef struct SrcList SrcList;
351 typedef struct ThreadData ThreadData;
352 typedef struct Table Table;
353 typedef struct TableLock TableLock;
354 typedef struct Token Token;
355 typedef struct TriggerStack TriggerStack;
356 typedef struct TriggerStep TriggerStep;
357 typedef struct Trigger Trigger;
358 typedef struct WhereInfo WhereInfo;
359 typedef struct WhereLevel WhereLevel;
360 
361 /*
362 ** Each database file to be accessed by the system is an instance
363 ** of the following structure.  There are normally two of these structures
364 ** in the sqlite.aDb[] array.  aDb[0] is the main database file and
365 ** aDb[1] is the database file used to hold temporary tables.  Additional
366 ** databases may be attached.
367 */
368 struct Db {
369   char *zName;         /* Name of this database */
370   Btree *pBt;          /* The B*Tree structure for this database file */
371   u8 inTrans;          /* 0: not writable.  1: Transaction.  2: Checkpoint */
372   u8 safety_level;     /* How aggressive at synching data to disk */
373   void *pAux;               /* Auxiliary data.  Usually NULL */
374   void (*xFreeAux)(void*);  /* Routine to free pAux */
375   Schema *pSchema;     /* Pointer to database schema (possibly shared) */
376 };
377 
378 /*
379 ** An instance of the following structure stores a database schema.
380 */
381 struct Schema {
382   int schema_cookie;   /* Database schema version number for this file */
383   Hash tblHash;        /* All tables indexed by name */
384   Hash idxHash;        /* All (named) indices indexed by name */
385   Hash trigHash;       /* All triggers indexed by name */
386   Hash aFKey;          /* Foreign keys indexed by to-table */
387   Table *pSeqTab;      /* The sqlite_sequence table used by AUTOINCREMENT */
388   u8 file_format;      /* Schema format version for this file */
389   u8 enc;              /* Text encoding used by this database */
390   u16 flags;           /* Flags associated with this schema */
391   int cache_size;      /* Number of pages to use in the cache */
392 };
393 
394 /*
395 ** These macros can be used to test, set, or clear bits in the
396 ** Db.flags field.
397 */
398 #define DbHasProperty(D,I,P)     (((D)->aDb[I].pSchema->flags&(P))==(P))
399 #define DbHasAnyProperty(D,I,P)  (((D)->aDb[I].pSchema->flags&(P))!=0)
400 #define DbSetProperty(D,I,P)     (D)->aDb[I].pSchema->flags|=(P)
401 #define DbClearProperty(D,I,P)   (D)->aDb[I].pSchema->flags&=~(P)
402 
403 /*
404 ** Allowed values for the DB.flags field.
405 **
406 ** The DB_SchemaLoaded flag is set after the database schema has been
407 ** read into internal hash tables.
408 **
409 ** DB_UnresetViews means that one or more views have column names that
410 ** have been filled out.  If the schema changes, these column names might
411 ** changes and so the view will need to be reset.
412 */
413 #define DB_SchemaLoaded    0x0001  /* The schema has been loaded */
414 #define DB_UnresetViews    0x0002  /* Some views have defined column names */
415 #define DB_Empty           0x0004  /* The file is empty (length 0 bytes) */
416 
417 #define SQLITE_UTF16NATIVE (SQLITE_BIGENDIAN?SQLITE_UTF16BE:SQLITE_UTF16LE)
418 
419 /*
420 ** Each database is an instance of the following structure.
421 **
422 ** The sqlite.lastRowid records the last insert rowid generated by an
423 ** insert statement.  Inserts on views do not affect its value.  Each
424 ** trigger has its own context, so that lastRowid can be updated inside
425 ** triggers as usual.  The previous value will be restored once the trigger
426 ** exits.  Upon entering a before or instead of trigger, lastRowid is no
427 ** longer (since after version 2.8.12) reset to -1.
428 **
429 ** The sqlite.nChange does not count changes within triggers and keeps no
430 ** context.  It is reset at start of sqlite3_exec.
431 ** The sqlite.lsChange represents the number of changes made by the last
432 ** insert, update, or delete statement.  It remains constant throughout the
433 ** length of a statement and is then updated by OP_SetCounts.  It keeps a
434 ** context stack just like lastRowid so that the count of changes
435 ** within a trigger is not seen outside the trigger.  Changes to views do not
436 ** affect the value of lsChange.
437 ** The sqlite.csChange keeps track of the number of current changes (since
438 ** the last statement) and is used to update sqlite_lsChange.
439 **
440 ** The member variables sqlite.errCode, sqlite.zErrMsg and sqlite.zErrMsg16
441 ** store the most recent error code and, if applicable, string. The
442 ** internal function sqlite3Error() is used to set these variables
443 ** consistently.
444 */
445 struct sqlite3 {
446   int nDb;                      /* Number of backends currently in use */
447   Db *aDb;                      /* All backends */
448   int flags;                    /* Miscellanous flags. See below */
449   int errCode;                  /* Most recent error code (SQLITE_*) */
450   int errMask;                  /* & result codes with this before returning */
451   u8 autoCommit;                /* The auto-commit flag. */
452   u8 temp_store;                /* 1: file 2: memory 0: default */
453   int nTable;                   /* Number of tables in the database */
454   CollSeq *pDfltColl;           /* The default collating sequence (BINARY) */
455   i64 lastRowid;                /* ROWID of most recent insert (see above) */
456   i64 priorNewRowid;            /* Last randomly generated ROWID */
457   int magic;                    /* Magic number for detect library misuse */
458   int nChange;                  /* Value returned by sqlite3_changes() */
459   int nTotalChange;             /* Value returned by sqlite3_total_changes() */
460   struct sqlite3InitInfo {      /* Information used during initialization */
461     int iDb;                    /* When back is being initialized */
462     int newTnum;                /* Rootpage of table being initialized */
463     u8 busy;                    /* TRUE if currently initializing */
464   } init;
465   int nExtension;               /* Number of loaded extensions */
466   void **aExtension;            /* Array of shared libraray handles */
467   struct Vdbe *pVdbe;           /* List of active virtual machines */
468   int activeVdbeCnt;            /* Number of vdbes currently executing */
469   void (*xTrace)(void*,const char*);        /* Trace function */
470   void *pTraceArg;                          /* Argument to the trace function */
471   void (*xProfile)(void*,const char*,u64);  /* Profiling function */
472   void *pProfileArg;                        /* Argument to profile function */
473   void *pCommitArg;                 /* Argument to xCommitCallback() */
474   int (*xCommitCallback)(void*);    /* Invoked at every commit. */
475   void *pRollbackArg;               /* Argument to xRollbackCallback() */
476   void (*xRollbackCallback)(void*); /* Invoked at every commit. */
477   void *pUpdateArg;
478   void (*xUpdateCallback)(void*,int, const char*,const char*,sqlite_int64);
479   void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*);
480   void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*);
481   void *pCollNeededArg;
482   sqlite3_value *pErr;          /* Most recent error message */
483   char *zErrMsg;                /* Most recent error message (UTF-8 encoded) */
484   char *zErrMsg16;              /* Most recent error message (UTF-16 encoded) */
485   union {
486     int isInterrupted;          /* True if sqlite3_interrupt has been called */
487     double notUsed1;            /* Spacer */
488   } u1;
489 #ifndef SQLITE_OMIT_AUTHORIZATION
490   int (*xAuth)(void*,int,const char*,const char*,const char*,const char*);
491                                 /* Access authorization function */
492   void *pAuthArg;               /* 1st argument to the access auth function */
493 #endif
494 #ifndef SQLITE_OMIT_PROGRESS_CALLBACK
495   int (*xProgress)(void *);     /* The progress callback */
496   void *pProgressArg;           /* Argument to the progress callback */
497   int nProgressOps;             /* Number of opcodes for progress callback */
498 #endif
499 #ifndef SQLITE_OMIT_VIRTUALTABLE
500   Hash aModule;                 /* populated by sqlite3_create_module() */
501   Table *pVTab;                 /* vtab with active Connect/Create method */
502   sqlite3_vtab **aVTrans;       /* Virtual tables with open transactions */
503   int nVTrans;                  /* Allocated size of aVTrans */
504 #endif
505   Hash aFunc;                   /* All functions that can be in SQL exprs */
506   Hash aCollSeq;                /* All collating sequences */
507   BusyHandler busyHandler;      /* Busy callback */
508   int busyTimeout;              /* Busy handler timeout, in msec */
509   Db aDbStatic[2];              /* Static space for the 2 default backends */
510 #ifdef SQLITE_SSE
511   sqlite3_stmt *pFetch;         /* Used by SSE to fetch stored statements */
512 #endif
513 };
514 
515 /*
516 ** A macro to discover the encoding of a database.
517 */
518 #define ENC(db) ((db)->aDb[0].pSchema->enc)
519 
520 /*
521 ** Possible values for the sqlite.flags and or Db.flags fields.
522 **
523 ** On sqlite.flags, the SQLITE_InTrans value means that we have
524 ** executed a BEGIN.  On Db.flags, SQLITE_InTrans means a statement
525 ** transaction is active on that particular database file.
526 */
527 #define SQLITE_VdbeTrace      0x00000001  /* True to trace VDBE execution */
528 #define SQLITE_InTrans        0x00000008  /* True if in a transaction */
529 #define SQLITE_InternChanges  0x00000010  /* Uncommitted Hash table changes */
530 #define SQLITE_FullColNames   0x00000020  /* Show full column names on SELECT */
531 #define SQLITE_ShortColNames  0x00000040  /* Show short columns names */
532 #define SQLITE_CountRows      0x00000080  /* Count rows changed by INSERT, */
533                                           /*   DELETE, or UPDATE and return */
534                                           /*   the count using a callback. */
535 #define SQLITE_NullCallback   0x00000100  /* Invoke the callback once if the */
536                                           /*   result set is empty */
537 #define SQLITE_SqlTrace       0x00000200  /* Debug print SQL as it executes */
538 #define SQLITE_VdbeListing    0x00000400  /* Debug listings of VDBE programs */
539 #define SQLITE_WriteSchema    0x00000800  /* OK to update SQLITE_MASTER */
540 #define SQLITE_NoReadlock     0x00001000  /* Readlocks are omitted when
541                                           ** accessing read-only databases */
542 #define SQLITE_IgnoreChecks   0x00002000  /* Do not enforce check constraints */
543 #define SQLITE_ReadUncommitted 0x00004000 /* For shared-cache mode */
544 #define SQLITE_LegacyFileFmt  0x00008000  /* Create new databases in format 1 */
545 #define SQLITE_FullFSync      0x00010000  /* Use full fsync on the backend */
546 #define SQLITE_LoadExtension  0x00020000  /* Enable load_extension */
547 
548 /*
549 ** Possible values for the sqlite.magic field.
550 ** The numbers are obtained at random and have no special meaning, other
551 ** than being distinct from one another.
552 */
553 #define SQLITE_MAGIC_OPEN     0xa029a697  /* Database is open */
554 #define SQLITE_MAGIC_CLOSED   0x9f3c2d33  /* Database is closed */
555 #define SQLITE_MAGIC_BUSY     0xf03b7906  /* Database currently in use */
556 #define SQLITE_MAGIC_ERROR    0xb5357930  /* An SQLITE_MISUSE error occurred */
557 
558 /*
559 ** Each SQL function is defined by an instance of the following
560 ** structure.  A pointer to this structure is stored in the sqlite.aFunc
561 ** hash table.  When multiple functions have the same name, the hash table
562 ** points to a linked list of these structures.
563 */
564 struct FuncDef {
565   i16 nArg;            /* Number of arguments.  -1 means unlimited */
566   u8 iPrefEnc;         /* Preferred text encoding (SQLITE_UTF8, 16LE, 16BE) */
567   u8 needCollSeq;      /* True if sqlite3GetFuncCollSeq() might be called */
568   u8 flags;            /* Some combination of SQLITE_FUNC_* */
569   void *pUserData;     /* User data parameter */
570   FuncDef *pNext;      /* Next function with same name */
571   void (*xFunc)(sqlite3_context*,int,sqlite3_value**); /* Regular function */
572   void (*xStep)(sqlite3_context*,int,sqlite3_value**); /* Aggregate step */
573   void (*xFinalize)(sqlite3_context*);                /* Aggregate finializer */
574   char zName[1];       /* SQL name of the function.  MUST BE LAST */
575 };
576 
577 /*
578 ** Each SQLite module (virtual table definition) is defined by an
579 ** instance of the following structure, stored in the sqlite3.aModule
580 ** hash table.
581 */
582 struct Module {
583   const sqlite3_module *pModule;       /* Callback pointers */
584   const char *zName;                   /* Name passed to create_module() */
585   void *pAux;                          /* pAux passed to create_module() */
586 };
587 
588 /*
589 ** Possible values for FuncDef.flags
590 */
591 #define SQLITE_FUNC_LIKE   0x01  /* Candidate for the LIKE optimization */
592 #define SQLITE_FUNC_CASE   0x02  /* Case-sensitive LIKE-type function */
593 #define SQLITE_FUNC_EPHEM  0x04  /* Ephermeral.  Delete with VDBE */
594 
595 /*
596 ** information about each column of an SQL table is held in an instance
597 ** of this structure.
598 */
599 struct Column {
600   char *zName;     /* Name of this column */
601   Expr *pDflt;     /* Default value of this column */
602   char *zType;     /* Data type for this column */
603   char *zColl;     /* Collating sequence.  If NULL, use the default */
604   u8 notNull;      /* True if there is a NOT NULL constraint */
605   u8 isPrimKey;    /* True if this column is part of the PRIMARY KEY */
606   char affinity;   /* One of the SQLITE_AFF_... values */
607 };
608 
609 /*
610 ** A "Collating Sequence" is defined by an instance of the following
611 ** structure. Conceptually, a collating sequence consists of a name and
612 ** a comparison routine that defines the order of that sequence.
613 **
614 ** There may two seperate implementations of the collation function, one
615 ** that processes text in UTF-8 encoding (CollSeq.xCmp) and another that
616 ** processes text encoded in UTF-16 (CollSeq.xCmp16), using the machine
617 ** native byte order. When a collation sequence is invoked, SQLite selects
618 ** the version that will require the least expensive encoding
619 ** translations, if any.
620 **
621 ** The CollSeq.pUser member variable is an extra parameter that passed in
622 ** as the first argument to the UTF-8 comparison function, xCmp.
623 ** CollSeq.pUser16 is the equivalent for the UTF-16 comparison function,
624 ** xCmp16.
625 **
626 ** If both CollSeq.xCmp and CollSeq.xCmp16 are NULL, it means that the
627 ** collating sequence is undefined.  Indices built on an undefined
628 ** collating sequence may not be read or written.
629 */
630 struct CollSeq {
631   char *zName;         /* Name of the collating sequence, UTF-8 encoded */
632   u8 enc;              /* Text encoding handled by xCmp() */
633   u8 type;             /* One of the SQLITE_COLL_... values below */
634   void *pUser;         /* First argument to xCmp() */
635   int (*xCmp)(void*,int, const void*, int, const void*);
636 };
637 
638 /*
639 ** Allowed values of CollSeq flags:
640 */
641 #define SQLITE_COLL_BINARY  1  /* The default memcmp() collating sequence */
642 #define SQLITE_COLL_NOCASE  2  /* The built-in NOCASE collating sequence */
643 #define SQLITE_COLL_REVERSE 3  /* The built-in REVERSE collating sequence */
644 #define SQLITE_COLL_USER    0  /* Any other user-defined collating sequence */
645 
646 /*
647 ** A sort order can be either ASC or DESC.
648 */
649 #define SQLITE_SO_ASC       0  /* Sort in ascending order */
650 #define SQLITE_SO_DESC      1  /* Sort in ascending order */
651 
652 /*
653 ** Column affinity types.
654 **
655 ** These used to have mnemonic name like 'i' for SQLITE_AFF_INTEGER and
656 ** 't' for SQLITE_AFF_TEXT.  But we can save a little space and improve
657 ** the speed a little by number the values consecutively.
658 **
659 ** But rather than start with 0 or 1, we begin with 'a'.  That way,
660 ** when multiple affinity types are concatenated into a string and
661 ** used as the P3 operand, they will be more readable.
662 **
663 ** Note also that the numeric types are grouped together so that testing
664 ** for a numeric type is a single comparison.
665 */
666 #define SQLITE_AFF_TEXT     'a'
667 #define SQLITE_AFF_NONE     'b'
668 #define SQLITE_AFF_NUMERIC  'c'
669 #define SQLITE_AFF_INTEGER  'd'
670 #define SQLITE_AFF_REAL     'e'
671 
672 #define sqlite3IsNumericAffinity(X)  ((X)>=SQLITE_AFF_NUMERIC)
673 
674 /*
675 ** Each SQL table is represented in memory by an instance of the
676 ** following structure.
677 **
678 ** Table.zName is the name of the table.  The case of the original
679 ** CREATE TABLE statement is stored, but case is not significant for
680 ** comparisons.
681 **
682 ** Table.nCol is the number of columns in this table.  Table.aCol is a
683 ** pointer to an array of Column structures, one for each column.
684 **
685 ** If the table has an INTEGER PRIMARY KEY, then Table.iPKey is the index of
686 ** the column that is that key.   Otherwise Table.iPKey is negative.  Note
687 ** that the datatype of the PRIMARY KEY must be INTEGER for this field to
688 ** be set.  An INTEGER PRIMARY KEY is used as the rowid for each row of
689 ** the table.  If a table has no INTEGER PRIMARY KEY, then a random rowid
690 ** is generated for each row of the table.  Table.hasPrimKey is true if
691 ** the table has any PRIMARY KEY, INTEGER or otherwise.
692 **
693 ** Table.tnum is the page number for the root BTree page of the table in the
694 ** database file.  If Table.iDb is the index of the database table backend
695 ** in sqlite.aDb[].  0 is for the main database and 1 is for the file that
696 ** holds temporary tables and indices.  If Table.isEphem
697 ** is true, then the table is stored in a file that is automatically deleted
698 ** when the VDBE cursor to the table is closed.  In this case Table.tnum
699 ** refers VDBE cursor number that holds the table open, not to the root
700 ** page number.  Transient tables are used to hold the results of a
701 ** sub-query that appears instead of a real table name in the FROM clause
702 ** of a SELECT statement.
703 */
704 struct Table {
705   char *zName;     /* Name of the table */
706   int nCol;        /* Number of columns in this table */
707   Column *aCol;    /* Information about each column */
708   int iPKey;       /* If not less then 0, use aCol[iPKey] as the primary key */
709   Index *pIndex;   /* List of SQL indexes on this table. */
710   int tnum;        /* Root BTree node for this table (see note above) */
711   Select *pSelect; /* NULL for tables.  Points to definition if a view. */
712   int nRef;          /* Number of pointers to this Table */
713   Trigger *pTrigger; /* List of SQL triggers on this table */
714   FKey *pFKey;       /* Linked list of all foreign keys in this table */
715   char *zColAff;     /* String defining the affinity of each column */
716 #ifndef SQLITE_OMIT_CHECK
717   Expr *pCheck;      /* The AND of all CHECK constraints */
718 #endif
719 #ifndef SQLITE_OMIT_ALTERTABLE
720   int addColOffset;  /* Offset in CREATE TABLE statement to add a new column */
721 #endif
722   u8 readOnly;     /* True if this table should not be written by the user */
723   u8 isEphem;      /* True if created using OP_OpenEphermeral */
724   u8 hasPrimKey;   /* True if there exists a primary key */
725   u8 keyConf;      /* What to do in case of uniqueness conflict on iPKey */
726   u8 autoInc;      /* True if the integer primary key is autoincrement */
727 #ifndef SQLITE_OMIT_VIRTUALTABLE
728   u8 isVirtual;             /* True if this is a virtual table */
729   u8 isCommit;              /* True once the CREATE TABLE has been committed */
730   Module *pMod;             /* Pointer to the implementation of the module */
731   sqlite3_vtab *pVtab;      /* Pointer to the module instance */
732   int nModuleArg;           /* Number of arguments to the module */
733   char **azModuleArg;       /* Text of all module args. [0] is module name */
734 #endif
735   Schema *pSchema;
736 };
737 
738 /*
739 ** Test to see whether or not a table is a virtual table.  This is
740 ** done as a macro so that it will be optimized out when virtual
741 ** table support is omitted from the build.
742 */
743 #ifndef SQLITE_OMIT_VIRTUALTABLE
744 #  define IsVirtual(X) ((X)->isVirtual)
745 #else
746 #  define IsVirtual(X) 0
747 #endif
748 
749 /*
750 ** Each foreign key constraint is an instance of the following structure.
751 **
752 ** A foreign key is associated with two tables.  The "from" table is
753 ** the table that contains the REFERENCES clause that creates the foreign
754 ** key.  The "to" table is the table that is named in the REFERENCES clause.
755 ** Consider this example:
756 **
757 **     CREATE TABLE ex1(
758 **       a INTEGER PRIMARY KEY,
759 **       b INTEGER CONSTRAINT fk1 REFERENCES ex2(x)
760 **     );
761 **
762 ** For foreign key "fk1", the from-table is "ex1" and the to-table is "ex2".
763 **
764 ** Each REFERENCES clause generates an instance of the following structure
765 ** which is attached to the from-table.  The to-table need not exist when
766 ** the from-table is created.  The existance of the to-table is not checked
767 ** until an attempt is made to insert data into the from-table.
768 **
769 ** The sqlite.aFKey hash table stores pointers to this structure
770 ** given the name of a to-table.  For each to-table, all foreign keys
771 ** associated with that table are on a linked list using the FKey.pNextTo
772 ** field.
773 */
774 struct FKey {
775   Table *pFrom;     /* The table that constains the REFERENCES clause */
776   FKey *pNextFrom;  /* Next foreign key in pFrom */
777   char *zTo;        /* Name of table that the key points to */
778   FKey *pNextTo;    /* Next foreign key that points to zTo */
779   int nCol;         /* Number of columns in this key */
780   struct sColMap {  /* Mapping of columns in pFrom to columns in zTo */
781     int iFrom;         /* Index of column in pFrom */
782     char *zCol;        /* Name of column in zTo.  If 0 use PRIMARY KEY */
783   } *aCol;          /* One entry for each of nCol column s */
784   u8 isDeferred;    /* True if constraint checking is deferred till COMMIT */
785   u8 updateConf;    /* How to resolve conflicts that occur on UPDATE */
786   u8 deleteConf;    /* How to resolve conflicts that occur on DELETE */
787   u8 insertConf;    /* How to resolve conflicts that occur on INSERT */
788 };
789 
790 /*
791 ** SQLite supports many different ways to resolve a contraint
792 ** error.  ROLLBACK processing means that a constraint violation
793 ** causes the operation in process to fail and for the current transaction
794 ** to be rolled back.  ABORT processing means the operation in process
795 ** fails and any prior changes from that one operation are backed out,
796 ** but the transaction is not rolled back.  FAIL processing means that
797 ** the operation in progress stops and returns an error code.  But prior
798 ** changes due to the same operation are not backed out and no rollback
799 ** occurs.  IGNORE means that the particular row that caused the constraint
800 ** error is not inserted or updated.  Processing continues and no error
801 ** is returned.  REPLACE means that preexisting database rows that caused
802 ** a UNIQUE constraint violation are removed so that the new insert or
803 ** update can proceed.  Processing continues and no error is reported.
804 **
805 ** RESTRICT, SETNULL, and CASCADE actions apply only to foreign keys.
806 ** RESTRICT is the same as ABORT for IMMEDIATE foreign keys and the
807 ** same as ROLLBACK for DEFERRED keys.  SETNULL means that the foreign
808 ** key is set to NULL.  CASCADE means that a DELETE or UPDATE of the
809 ** referenced table row is propagated into the row that holds the
810 ** foreign key.
811 **
812 ** The following symbolic values are used to record which type
813 ** of action to take.
814 */
815 #define OE_None     0   /* There is no constraint to check */
816 #define OE_Rollback 1   /* Fail the operation and rollback the transaction */
817 #define OE_Abort    2   /* Back out changes but do no rollback transaction */
818 #define OE_Fail     3   /* Stop the operation but leave all prior changes */
819 #define OE_Ignore   4   /* Ignore the error. Do not do the INSERT or UPDATE */
820 #define OE_Replace  5   /* Delete existing record, then do INSERT or UPDATE */
821 
822 #define OE_Restrict 6   /* OE_Abort for IMMEDIATE, OE_Rollback for DEFERRED */
823 #define OE_SetNull  7   /* Set the foreign key value to NULL */
824 #define OE_SetDflt  8   /* Set the foreign key value to its default */
825 #define OE_Cascade  9   /* Cascade the changes */
826 
827 #define OE_Default  99  /* Do whatever the default action is */
828 
829 
830 /*
831 ** An instance of the following structure is passed as the first
832 ** argument to sqlite3VdbeKeyCompare and is used to control the
833 ** comparison of the two index keys.
834 **
835 ** If the KeyInfo.incrKey value is true and the comparison would
836 ** otherwise be equal, then return a result as if the second key
837 ** were larger.
838 */
839 struct KeyInfo {
840   u8 enc;             /* Text encoding - one of the TEXT_Utf* values */
841   u8 incrKey;         /* Increase 2nd key by epsilon before comparison */
842   int nField;         /* Number of entries in aColl[] */
843   u8 *aSortOrder;     /* If defined an aSortOrder[i] is true, sort DESC */
844   CollSeq *aColl[1];  /* Collating sequence for each term of the key */
845 };
846 
847 /*
848 ** Each SQL index is represented in memory by an
849 ** instance of the following structure.
850 **
851 ** The columns of the table that are to be indexed are described
852 ** by the aiColumn[] field of this structure.  For example, suppose
853 ** we have the following table and index:
854 **
855 **     CREATE TABLE Ex1(c1 int, c2 int, c3 text);
856 **     CREATE INDEX Ex2 ON Ex1(c3,c1);
857 **
858 ** In the Table structure describing Ex1, nCol==3 because there are
859 ** three columns in the table.  In the Index structure describing
860 ** Ex2, nColumn==2 since 2 of the 3 columns of Ex1 are indexed.
861 ** The value of aiColumn is {2, 0}.  aiColumn[0]==2 because the
862 ** first column to be indexed (c3) has an index of 2 in Ex1.aCol[].
863 ** The second column to be indexed (c1) has an index of 0 in
864 ** Ex1.aCol[], hence Ex2.aiColumn[1]==0.
865 **
866 ** The Index.onError field determines whether or not the indexed columns
867 ** must be unique and what to do if they are not.  When Index.onError=OE_None,
868 ** it means this is not a unique index.  Otherwise it is a unique index
869 ** and the value of Index.onError indicate the which conflict resolution
870 ** algorithm to employ whenever an attempt is made to insert a non-unique
871 ** element.
872 */
873 struct Index {
874   char *zName;     /* Name of this index */
875   int nColumn;     /* Number of columns in the table used by this index */
876   int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
877   unsigned *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
878   Table *pTable;   /* The SQL table being indexed */
879   int tnum;        /* Page containing root of this index in database file */
880   u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
881   u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */
882   char *zColAff;   /* String defining the affinity of each column */
883   Index *pNext;    /* The next index associated with the same table */
884   Schema *pSchema; /* Schema containing this index */
885   u8 *aSortOrder;  /* Array of size Index.nColumn. True==DESC, False==ASC */
886   char **azColl;   /* Array of collation sequence names for index */
887 };
888 
889 /*
890 ** Each token coming out of the lexer is an instance of
891 ** this structure.  Tokens are also used as part of an expression.
892 **
893 ** Note if Token.z==0 then Token.dyn and Token.n are undefined and
894 ** may contain random values.  Do not make any assuptions about Token.dyn
895 ** and Token.n when Token.z==0.
896 */
897 struct Token {
898   const unsigned char *z; /* Text of the token.  Not NULL-terminated! */
899   unsigned dyn  : 1;      /* True for malloced memory, false for static */
900   unsigned n    : 31;     /* Number of characters in this token */
901 };
902 
903 /*
904 ** An instance of this structure contains information needed to generate
905 ** code for a SELECT that contains aggregate functions.
906 **
907 ** If Expr.op==TK_AGG_COLUMN or TK_AGG_FUNCTION then Expr.pAggInfo is a
908 ** pointer to this structure.  The Expr.iColumn field is the index in
909 ** AggInfo.aCol[] or AggInfo.aFunc[] of information needed to generate
910 ** code for that node.
911 **
912 ** AggInfo.pGroupBy and AggInfo.aFunc.pExpr point to fields within the
913 ** original Select structure that describes the SELECT statement.  These
914 ** fields do not need to be freed when deallocating the AggInfo structure.
915 */
916 struct AggInfo {
917   u8 directMode;          /* Direct rendering mode means take data directly
918                           ** from source tables rather than from accumulators */
919   u8 useSortingIdx;       /* In direct mode, reference the sorting index rather
920                           ** than the source table */
921   int sortingIdx;         /* Cursor number of the sorting index */
922   ExprList *pGroupBy;     /* The group by clause */
923   int nSortingColumn;     /* Number of columns in the sorting index */
924   struct AggInfo_col {    /* For each column used in source tables */
925     Table *pTab;             /* Source table */
926     int iTable;              /* Cursor number of the source table */
927     int iColumn;             /* Column number within the source table */
928     int iSorterColumn;       /* Column number in the sorting index */
929     int iMem;                /* Memory location that acts as accumulator */
930     Expr *pExpr;             /* The original expression */
931   } *aCol;
932   int nColumn;            /* Number of used entries in aCol[] */
933   int nColumnAlloc;       /* Number of slots allocated for aCol[] */
934   int nAccumulator;       /* Number of columns that show through to the output.
935                           ** Additional columns are used only as parameters to
936                           ** aggregate functions */
937   struct AggInfo_func {   /* For each aggregate function */
938     Expr *pExpr;             /* Expression encoding the function */
939     FuncDef *pFunc;          /* The aggregate function implementation */
940     int iMem;                /* Memory location that acts as accumulator */
941     int iDistinct;           /* Ephermeral table used to enforce DISTINCT */
942   } *aFunc;
943   int nFunc;              /* Number of entries in aFunc[] */
944   int nFuncAlloc;         /* Number of slots allocated for aFunc[] */
945 };
946 
947 /*
948 ** Each node of an expression in the parse tree is an instance
949 ** of this structure.
950 **
951 ** Expr.op is the opcode.  The integer parser token codes are reused
952 ** as opcodes here.  For example, the parser defines TK_GE to be an integer
953 ** code representing the ">=" operator.  This same integer code is reused
954 ** to represent the greater-than-or-equal-to operator in the expression
955 ** tree.
956 **
957 ** Expr.pRight and Expr.pLeft are subexpressions.  Expr.pList is a list
958 ** of argument if the expression is a function.
959 **
960 ** Expr.token is the operator token for this node.  For some expressions
961 ** that have subexpressions, Expr.token can be the complete text that gave
962 ** rise to the Expr.  In the latter case, the token is marked as being
963 ** a compound token.
964 **
965 ** An expression of the form ID or ID.ID refers to a column in a table.
966 ** For such expressions, Expr.op is set to TK_COLUMN and Expr.iTable is
967 ** the integer cursor number of a VDBE cursor pointing to that table and
968 ** Expr.iColumn is the column number for the specific column.  If the
969 ** expression is used as a result in an aggregate SELECT, then the
970 ** value is also stored in the Expr.iAgg column in the aggregate so that
971 ** it can be accessed after all aggregates are computed.
972 **
973 ** If the expression is a function, the Expr.iTable is an integer code
974 ** representing which function.  If the expression is an unbound variable
975 ** marker (a question mark character '?' in the original SQL) then the
976 ** Expr.iTable holds the index number for that variable.
977 **
978 ** If the expression is a subquery then Expr.iColumn holds an integer
979 ** register number containing the result of the subquery.  If the
980 ** subquery gives a constant result, then iTable is -1.  If the subquery
981 ** gives a different answer at different times during statement processing
982 ** then iTable is the address of a subroutine that computes the subquery.
983 **
984 ** The Expr.pSelect field points to a SELECT statement.  The SELECT might
985 ** be the right operand of an IN operator.  Or, if a scalar SELECT appears
986 ** in an expression the opcode is TK_SELECT and Expr.pSelect is the only
987 ** operand.
988 **
989 ** If the Expr is of type OP_Column, and the table it is selecting from
990 ** is a disk table or the "old.*" pseudo-table, then pTab points to the
991 ** corresponding table definition.
992 */
993 struct Expr {
994   u8 op;                 /* Operation performed by this node */
995   char affinity;         /* The affinity of the column or 0 if not a column */
996   u16 flags;             /* Various flags.  See below */
997   CollSeq *pColl;        /* The collation type of the column or 0 */
998   Expr *pLeft, *pRight;  /* Left and right subnodes */
999   ExprList *pList;       /* A list of expressions used as function arguments
1000                          ** or in "<expr> IN (<expr-list)" */
1001   Token token;           /* An operand token */
1002   Token span;            /* Complete text of the expression */
1003   int iTable, iColumn;   /* When op==TK_COLUMN, then this expr node means the
1004                          ** iColumn-th field of the iTable-th table. */
1005   AggInfo *pAggInfo;     /* Used by TK_AGG_COLUMN and TK_AGG_FUNCTION */
1006   int iAgg;              /* Which entry in pAggInfo->aCol[] or ->aFunc[] */
1007   int iRightJoinTable;   /* If EP_FromJoin, the right table of the join */
1008   Select *pSelect;       /* When the expression is a sub-select.  Also the
1009                          ** right side of "<expr> IN (<select>)" */
1010   Table *pTab;           /* Table for OP_Column expressions. */
1011   Schema *pSchema;
1012 };
1013 
1014 /*
1015 ** The following are the meanings of bits in the Expr.flags field.
1016 */
1017 #define EP_FromJoin     0x01  /* Originated in ON or USING clause of a join */
1018 #define EP_Agg          0x02  /* Contains one or more aggregate functions */
1019 #define EP_Resolved     0x04  /* IDs have been resolved to COLUMNs */
1020 #define EP_Error        0x08  /* Expression contains one or more errors */
1021 #define EP_Distinct     0x10  /* Aggregate function with DISTINCT keyword */
1022 #define EP_VarSelect    0x20  /* pSelect is correlated, not constant */
1023 #define EP_Dequoted     0x40  /* True if the string has been dequoted */
1024 #define EP_InfixFunc    0x80  /* True for an infix function: LIKE, GLOB, etc */
1025 #define EP_ExpCollate  0x100  /* Collating sequence specified explicitly */
1026 
1027 /*
1028 ** These macros can be used to test, set, or clear bits in the
1029 ** Expr.flags field.
1030 */
1031 #define ExprHasProperty(E,P)     (((E)->flags&(P))==(P))
1032 #define ExprHasAnyProperty(E,P)  (((E)->flags&(P))!=0)
1033 #define ExprSetProperty(E,P)     (E)->flags|=(P)
1034 #define ExprClearProperty(E,P)   (E)->flags&=~(P)
1035 
1036 /*
1037 ** A list of expressions.  Each expression may optionally have a
1038 ** name.  An expr/name combination can be used in several ways, such
1039 ** as the list of "expr AS ID" fields following a "SELECT" or in the
1040 ** list of "ID = expr" items in an UPDATE.  A list of expressions can
1041 ** also be used as the argument to a function, in which case the a.zName
1042 ** field is not used.
1043 */
1044 struct ExprList {
1045   int nExpr;             /* Number of expressions on the list */
1046   int nAlloc;            /* Number of entries allocated below */
1047   int iECursor;          /* VDBE Cursor associated with this ExprList */
1048   struct ExprList_item {
1049     Expr *pExpr;           /* The list of expressions */
1050     char *zName;           /* Token associated with this expression */
1051     u8 sortOrder;          /* 1 for DESC or 0 for ASC */
1052     u8 isAgg;              /* True if this is an aggregate like count(*) */
1053     u8 done;               /* A flag to indicate when processing is finished */
1054   } *a;                  /* One entry for each expression */
1055 };
1056 
1057 /*
1058 ** An instance of this structure can hold a simple list of identifiers,
1059 ** such as the list "a,b,c" in the following statements:
1060 **
1061 **      INSERT INTO t(a,b,c) VALUES ...;
1062 **      CREATE INDEX idx ON t(a,b,c);
1063 **      CREATE TRIGGER trig BEFORE UPDATE ON t(a,b,c) ...;
1064 **
1065 ** The IdList.a.idx field is used when the IdList represents the list of
1066 ** column names after a table name in an INSERT statement.  In the statement
1067 **
1068 **     INSERT INTO t(a,b,c) ...
1069 **
1070 ** If "a" is the k-th column of table "t", then IdList.a[0].idx==k.
1071 */
1072 struct IdList {
1073   struct IdList_item {
1074     char *zName;      /* Name of the identifier */
1075     int idx;          /* Index in some Table.aCol[] of a column named zName */
1076   } *a;
1077   int nId;         /* Number of identifiers on the list */
1078   int nAlloc;      /* Number of entries allocated for a[] below */
1079 };
1080 
1081 /*
1082 ** The bitmask datatype defined below is used for various optimizations.
1083 **
1084 ** Changing this from a 64-bit to a 32-bit type limits the number of
1085 ** tables in a join to 32 instead of 64.  But it also reduces the size
1086 ** of the library by 738 bytes on ix86.
1087 */
1088 typedef u64 Bitmask;
1089 
1090 /*
1091 ** The following structure describes the FROM clause of a SELECT statement.
1092 ** Each table or subquery in the FROM clause is a separate element of
1093 ** the SrcList.a[] array.
1094 **
1095 ** With the addition of multiple database support, the following structure
1096 ** can also be used to describe a particular table such as the table that
1097 ** is modified by an INSERT, DELETE, or UPDATE statement.  In standard SQL,
1098 ** such a table must be a simple name: ID.  But in SQLite, the table can
1099 ** now be identified by a database name, a dot, then the table name: ID.ID.
1100 **
1101 ** The jointype starts out showing the join type between the current table
1102 ** and the next table on the list.  The parser builds the list this way.
1103 ** But sqlite3SrcListShiftJoinType() later shifts the jointypes so that each
1104 ** jointype expresses the join between the table and the previous table.
1105 */
1106 struct SrcList {
1107   i16 nSrc;        /* Number of tables or subqueries in the FROM clause */
1108   i16 nAlloc;      /* Number of entries allocated in a[] below */
1109   struct SrcList_item {
1110     char *zDatabase;  /* Name of database holding this table */
1111     char *zName;      /* Name of the table */
1112     char *zAlias;     /* The "B" part of a "A AS B" phrase.  zName is the "A" */
1113     Table *pTab;      /* An SQL table corresponding to zName */
1114     Select *pSelect;  /* A SELECT statement used in place of a table name */
1115     u8 isPopulated;   /* Temporary table associated with SELECT is populated */
1116     u8 jointype;      /* Type of join between this able and the previous */
1117     int iCursor;      /* The VDBE cursor number used to access this table */
1118     Expr *pOn;        /* The ON clause of a join */
1119     IdList *pUsing;   /* The USING clause of a join */
1120     Bitmask colUsed;  /* Bit N (1<<N) set if column N or pTab is used */
1121   } a[1];             /* One entry for each identifier on the list */
1122 };
1123 
1124 /*
1125 ** Permitted values of the SrcList.a.jointype field
1126 */
1127 #define JT_INNER     0x0001    /* Any kind of inner or cross join */
1128 #define JT_CROSS     0x0002    /* Explicit use of the CROSS keyword */
1129 #define JT_NATURAL   0x0004    /* True for a "natural" join */
1130 #define JT_LEFT      0x0008    /* Left outer join */
1131 #define JT_RIGHT     0x0010    /* Right outer join */
1132 #define JT_OUTER     0x0020    /* The "OUTER" keyword is present */
1133 #define JT_ERROR     0x0040    /* unknown or unsupported join type */
1134 
1135 /*
1136 ** For each nested loop in a WHERE clause implementation, the WhereInfo
1137 ** structure contains a single instance of this structure.  This structure
1138 ** is intended to be private the the where.c module and should not be
1139 ** access or modified by other modules.
1140 **
1141 ** The pIdxInfo and pBestIdx fields are used to help pick the best
1142 ** index on a virtual table.  The pIdxInfo pointer contains indexing
1143 ** information for the i-th table in the FROM clause before reordering.
1144 ** All the pIdxInfo pointers are freed by whereInfoFree() in where.c.
1145 ** The pBestIdx pointer is a copy of pIdxInfo for the i-th table after
1146 ** FROM clause ordering.  This is a little confusing so I will repeat
1147 ** it in different words.  WhereInfo.a[i].pIdxInfo is index information
1148 ** for WhereInfo.pTabList.a[i].  WhereInfo.a[i].pBestInfo is the
1149 ** index information for the i-th loop of the join.  pBestInfo is always
1150 ** either NULL or a copy of some pIdxInfo.  So for cleanup it is
1151 ** sufficient to free all of the pIdxInfo pointers.
1152 **
1153 */
1154 struct WhereLevel {
1155   int iFrom;            /* Which entry in the FROM clause */
1156   int flags;            /* Flags associated with this level */
1157   int iMem;             /* First memory cell used by this level */
1158   int iLeftJoin;        /* Memory cell used to implement LEFT OUTER JOIN */
1159   Index *pIdx;          /* Index used.  NULL if no index */
1160   int iTabCur;          /* The VDBE cursor used to access the table */
1161   int iIdxCur;          /* The VDBE cursor used to acesss pIdx */
1162   int brk;              /* Jump here to break out of the loop */
1163   int cont;             /* Jump here to continue with the next loop cycle */
1164   int top;              /* First instruction of interior of the loop */
1165   int op, p1, p2;       /* Opcode used to terminate the loop */
1166   int nEq;              /* Number of == or IN constraints on this loop */
1167   int nIn;              /* Number of IN operators constraining this loop */
1168   int *aInLoop;         /* Loop terminators for IN operators */
1169   sqlite3_index_info *pBestIdx;  /* Index information for this level */
1170 
1171   /* The following field is really not part of the current level.  But
1172   ** we need a place to cache index information for each table in the
1173   ** FROM clause and the WhereLevel structure is a convenient place.
1174   */
1175   sqlite3_index_info *pIdxInfo;  /* Index info for n-th source table */
1176 };
1177 
1178 /*
1179 ** The WHERE clause processing routine has two halves.  The
1180 ** first part does the start of the WHERE loop and the second
1181 ** half does the tail of the WHERE loop.  An instance of
1182 ** this structure is returned by the first half and passed
1183 ** into the second half to give some continuity.
1184 */
1185 struct WhereInfo {
1186   Parse *pParse;
1187   SrcList *pTabList;   /* List of tables in the join */
1188   int iTop;            /* The very beginning of the WHERE loop */
1189   int iContinue;       /* Jump here to continue with next record */
1190   int iBreak;          /* Jump here to break out of the loop */
1191   int nLevel;          /* Number of nested loop */
1192   sqlite3_index_info **apInfo;  /* Array of pointers to index info structures */
1193   WhereLevel a[1];     /* Information about each nest loop in the WHERE */
1194 };
1195 
1196 /*
1197 ** A NameContext defines a context in which to resolve table and column
1198 ** names.  The context consists of a list of tables (the pSrcList) field and
1199 ** a list of named expression (pEList).  The named expression list may
1200 ** be NULL.  The pSrc corresponds to the FROM clause of a SELECT or
1201 ** to the table being operated on by INSERT, UPDATE, or DELETE.  The
1202 ** pEList corresponds to the result set of a SELECT and is NULL for
1203 ** other statements.
1204 **
1205 ** NameContexts can be nested.  When resolving names, the inner-most
1206 ** context is searched first.  If no match is found, the next outer
1207 ** context is checked.  If there is still no match, the next context
1208 ** is checked.  This process continues until either a match is found
1209 ** or all contexts are check.  When a match is found, the nRef member of
1210 ** the context containing the match is incremented.
1211 **
1212 ** Each subquery gets a new NameContext.  The pNext field points to the
1213 ** NameContext in the parent query.  Thus the process of scanning the
1214 ** NameContext list corresponds to searching through successively outer
1215 ** subqueries looking for a match.
1216 */
1217 struct NameContext {
1218   Parse *pParse;       /* The parser */
1219   SrcList *pSrcList;   /* One or more tables used to resolve names */
1220   ExprList *pEList;    /* Optional list of named expressions */
1221   int nRef;            /* Number of names resolved by this context */
1222   int nErr;            /* Number of errors encountered while resolving names */
1223   u8 allowAgg;         /* Aggregate functions allowed here */
1224   u8 hasAgg;           /* True if aggregates are seen */
1225   u8 isCheck;          /* True if resolving names in a CHECK constraint */
1226   int nDepth;          /* Depth of subquery recursion. 1 for no recursion */
1227   AggInfo *pAggInfo;   /* Information about aggregates at this level */
1228   NameContext *pNext;  /* Next outer name context.  NULL for outermost */
1229 };
1230 
1231 /*
1232 ** An instance of the following structure contains all information
1233 ** needed to generate code for a single SELECT statement.
1234 **
1235 ** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
1236 ** If there is a LIMIT clause, the parser sets nLimit to the value of the
1237 ** limit and nOffset to the value of the offset (or 0 if there is not
1238 ** offset).  But later on, nLimit and nOffset become the memory locations
1239 ** in the VDBE that record the limit and offset counters.
1240 **
1241 ** addrOpenEphm[] entries contain the address of OP_OpenEphemeral opcodes.
1242 ** These addresses must be stored so that we can go back and fill in
1243 ** the P3_KEYINFO and P2 parameters later.  Neither the KeyInfo nor
1244 ** the number of columns in P2 can be computed at the same time
1245 ** as the OP_OpenEphm instruction is coded because not
1246 ** enough information about the compound query is known at that point.
1247 ** The KeyInfo for addrOpenTran[0] and [1] contains collating sequences
1248 ** for the result set.  The KeyInfo for addrOpenTran[2] contains collating
1249 ** sequences for the ORDER BY clause.
1250 */
1251 struct Select {
1252   ExprList *pEList;      /* The fields of the result */
1253   u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
1254   u8 isDistinct;         /* True if the DISTINCT keyword is present */
1255   u8 isResolved;         /* True once sqlite3SelectResolve() has run. */
1256   u8 isAgg;              /* True if this is an aggregate query */
1257   u8 usesEphm;           /* True if uses an OpenEphemeral opcode */
1258   u8 disallowOrderBy;    /* Do not allow an ORDER BY to be attached if TRUE */
1259   SrcList *pSrc;         /* The FROM clause */
1260   Expr *pWhere;          /* The WHERE clause */
1261   ExprList *pGroupBy;    /* The GROUP BY clause */
1262   Expr *pHaving;         /* The HAVING clause */
1263   ExprList *pOrderBy;    /* The ORDER BY clause */
1264   Select *pPrior;        /* Prior select in a compound select statement */
1265   Select *pRightmost;    /* Right-most select in a compound select statement */
1266   Expr *pLimit;          /* LIMIT expression. NULL means not used. */
1267   Expr *pOffset;         /* OFFSET expression. NULL means not used. */
1268   int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
1269   int addrOpenEphm[3];   /* OP_OpenEphem opcodes related to this select */
1270 };
1271 
1272 /*
1273 ** The results of a select can be distributed in several ways.
1274 */
1275 #define SRT_Union        1  /* Store result as keys in an index */
1276 #define SRT_Except       2  /* Remove result from a UNION index */
1277 #define SRT_Discard      3  /* Do not save the results anywhere */
1278 
1279 /* The ORDER BY clause is ignored for all of the above */
1280 #define IgnorableOrderby(X) (X<=SRT_Discard)
1281 
1282 #define SRT_Callback     4  /* Invoke a callback with each row of result */
1283 #define SRT_Mem          5  /* Store result in a memory cell */
1284 #define SRT_Set          6  /* Store non-null results as keys in an index */
1285 #define SRT_Table        7  /* Store result as data with an automatic rowid */
1286 #define SRT_EphemTab     8  /* Create transient tab and store like SRT_Table */
1287 #define SRT_Subroutine   9  /* Call a subroutine to handle results */
1288 #define SRT_Exists      10  /* Store 1 if the result is not empty */
1289 
1290 /*
1291 ** An SQL parser context.  A copy of this structure is passed through
1292 ** the parser and down into all the parser action routine in order to
1293 ** carry around information that is global to the entire parse.
1294 **
1295 ** The structure is divided into two parts.  When the parser and code
1296 ** generate call themselves recursively, the first part of the structure
1297 ** is constant but the second part is reset at the beginning and end of
1298 ** each recursion.
1299 **
1300 ** The nTableLock and aTableLock variables are only used if the shared-cache
1301 ** feature is enabled (if sqlite3Tsd()->useSharedData is true). They are
1302 ** used to store the set of table-locks required by the statement being
1303 ** compiled. Function sqlite3TableLock() is used to add entries to the
1304 ** list.
1305 */
1306 struct Parse {
1307   sqlite3 *db;         /* The main database structure */
1308   int rc;              /* Return code from execution */
1309   char *zErrMsg;       /* An error message */
1310   Vdbe *pVdbe;         /* An engine for executing database bytecode */
1311   u8 colNamesSet;      /* TRUE after OP_ColumnName has been issued to pVdbe */
1312   u8 nameClash;        /* A permanent table name clashes with temp table name */
1313   u8 checkSchema;      /* Causes schema cookie check after an error */
1314   u8 nested;           /* Number of nested calls to the parser/code generator */
1315   u8 parseError;       /* True if a parsing error has been seen */
1316   int nErr;            /* Number of errors seen */
1317   int nTab;            /* Number of previously allocated VDBE cursors */
1318   int nMem;            /* Number of memory cells used so far */
1319   int nSet;            /* Number of sets used so far */
1320   int ckOffset;        /* Stack offset to data used by CHECK constraints */
1321   u32 writeMask;       /* Start a write transaction on these databases */
1322   u32 cookieMask;      /* Bitmask of schema verified databases */
1323   int cookieGoto;      /* Address of OP_Goto to cookie verifier subroutine */
1324   int cookieValue[MAX_ATTACHED+2];  /* Values of cookies to verify */
1325 #ifndef SQLITE_OMIT_SHARED_CACHE
1326   int nTableLock;        /* Number of locks in aTableLock */
1327   TableLock *aTableLock; /* Required table locks for shared-cache mode */
1328 #endif
1329 
1330   /* Above is constant between recursions.  Below is reset before and after
1331   ** each recursion */
1332 
1333   int nVar;            /* Number of '?' variables seen in the SQL so far */
1334   int nVarExpr;        /* Number of used slots in apVarExpr[] */
1335   int nVarExprAlloc;   /* Number of allocated slots in apVarExpr[] */
1336   Expr **apVarExpr;    /* Pointers to :aaa and $aaaa wildcard expressions */
1337   u8 explain;          /* True if the EXPLAIN flag is found on the query */
1338   Token sErrToken;     /* The token at which the error occurred */
1339   Token sNameToken;    /* Token with unqualified schema object name */
1340   Token sLastToken;    /* The last token parsed */
1341   const char *zSql;    /* All SQL text */
1342   const char *zTail;   /* All SQL text past the last semicolon parsed */
1343   Table *pNewTable;    /* A table being constructed by CREATE TABLE */
1344   Trigger *pNewTrigger;     /* Trigger under construct by a CREATE TRIGGER */
1345   TriggerStack *trigStack;  /* Trigger actions being coded */
1346   const char *zAuthContext; /* The 6th parameter to db->xAuth callbacks */
1347 #ifndef SQLITE_OMIT_VIRTUALTABLE
1348   Token sArg;                /* Complete text of a module argument */
1349   u8 declareVtab;            /* True if inside sqlite3_declare_vtab() */
1350   Table *pVirtualLock;       /* Require virtual table lock on this table */
1351 #endif
1352 };
1353 
1354 #ifdef SQLITE_OMIT_VIRTUALTABLE
1355   #define IN_DECLARE_VTAB 0
1356 #else
1357   #define IN_DECLARE_VTAB (pParse->declareVtab)
1358 #endif
1359 
1360 /*
1361 ** An instance of the following structure can be declared on a stack and used
1362 ** to save the Parse.zAuthContext value so that it can be restored later.
1363 */
1364 struct AuthContext {
1365   const char *zAuthContext;   /* Put saved Parse.zAuthContext here */
1366   Parse *pParse;              /* The Parse structure */
1367 };
1368 
1369 /*
1370 ** Bitfield flags for P2 value in OP_Insert and OP_Delete
1371 */
1372 #define OPFLAG_NCHANGE   1    /* Set to update db->nChange */
1373 #define OPFLAG_LASTROWID 2    /* Set to update db->lastRowid */
1374 #define OPFLAG_ISUPDATE  4    /* This OP_Insert is an sql UPDATE */
1375 
1376 /*
1377  * Each trigger present in the database schema is stored as an instance of
1378  * struct Trigger.
1379  *
1380  * Pointers to instances of struct Trigger are stored in two ways.
1381  * 1. In the "trigHash" hash table (part of the sqlite3* that represents the
1382  *    database). This allows Trigger structures to be retrieved by name.
1383  * 2. All triggers associated with a single table form a linked list, using the
1384  *    pNext member of struct Trigger. A pointer to the first element of the
1385  *    linked list is stored as the "pTrigger" member of the associated
1386  *    struct Table.
1387  *
1388  * The "step_list" member points to the first element of a linked list
1389  * containing the SQL statements specified as the trigger program.
1390  */
1391 struct Trigger {
1392   char *name;             /* The name of the trigger                        */
1393   char *table;            /* The table or view to which the trigger applies */
1394   u8 op;                  /* One of TK_DELETE, TK_UPDATE, TK_INSERT         */
1395   u8 tr_tm;               /* One of TRIGGER_BEFORE, TRIGGER_AFTER */
1396   Expr *pWhen;            /* The WHEN clause of the expresion (may be NULL) */
1397   IdList *pColumns;       /* If this is an UPDATE OF <column-list> trigger,
1398                              the <column-list> is stored here */
1399   int foreach;            /* One of TK_ROW or TK_STATEMENT */
1400   Token nameToken;        /* Token containing zName. Use during parsing only */
1401   Schema *pSchema;        /* Schema containing the trigger */
1402   Schema *pTabSchema;     /* Schema containing the table */
1403   TriggerStep *step_list; /* Link list of trigger program steps             */
1404   Trigger *pNext;         /* Next trigger associated with the table */
1405 };
1406 
1407 /*
1408 ** A trigger is either a BEFORE or an AFTER trigger.  The following constants
1409 ** determine which.
1410 **
1411 ** If there are multiple triggers, you might of some BEFORE and some AFTER.
1412 ** In that cases, the constants below can be ORed together.
1413 */
1414 #define TRIGGER_BEFORE  1
1415 #define TRIGGER_AFTER   2
1416 
1417 /*
1418  * An instance of struct TriggerStep is used to store a single SQL statement
1419  * that is a part of a trigger-program.
1420  *
1421  * Instances of struct TriggerStep are stored in a singly linked list (linked
1422  * using the "pNext" member) referenced by the "step_list" member of the
1423  * associated struct Trigger instance. The first element of the linked list is
1424  * the first step of the trigger-program.
1425  *
1426  * The "op" member indicates whether this is a "DELETE", "INSERT", "UPDATE" or
1427  * "SELECT" statement. The meanings of the other members is determined by the
1428  * value of "op" as follows:
1429  *
1430  * (op == TK_INSERT)
1431  * orconf    -> stores the ON CONFLICT algorithm
1432  * pSelect   -> If this is an INSERT INTO ... SELECT ... statement, then
1433  *              this stores a pointer to the SELECT statement. Otherwise NULL.
1434  * target    -> A token holding the name of the table to insert into.
1435  * pExprList -> If this is an INSERT INTO ... VALUES ... statement, then
1436  *              this stores values to be inserted. Otherwise NULL.
1437  * pIdList   -> If this is an INSERT INTO ... (<column-names>) VALUES ...
1438  *              statement, then this stores the column-names to be
1439  *              inserted into.
1440  *
1441  * (op == TK_DELETE)
1442  * target    -> A token holding the name of the table to delete from.
1443  * pWhere    -> The WHERE clause of the DELETE statement if one is specified.
1444  *              Otherwise NULL.
1445  *
1446  * (op == TK_UPDATE)
1447  * target    -> A token holding the name of the table to update rows of.
1448  * pWhere    -> The WHERE clause of the UPDATE statement if one is specified.
1449  *              Otherwise NULL.
1450  * pExprList -> A list of the columns to update and the expressions to update
1451  *              them to. See sqlite3Update() documentation of "pChanges"
1452  *              argument.
1453  *
1454  */
1455 struct TriggerStep {
1456   int op;              /* One of TK_DELETE, TK_UPDATE, TK_INSERT, TK_SELECT */
1457   int orconf;          /* OE_Rollback etc. */
1458   Trigger *pTrig;      /* The trigger that this step is a part of */
1459 
1460   Select *pSelect;     /* Valid for SELECT and sometimes
1461 			  INSERT steps (when pExprList == 0) */
1462   Token target;        /* Valid for DELETE, UPDATE, INSERT steps */
1463   Expr *pWhere;        /* Valid for DELETE, UPDATE steps */
1464   ExprList *pExprList; /* Valid for UPDATE statements and sometimes
1465 			   INSERT steps (when pSelect == 0)         */
1466   IdList *pIdList;     /* Valid for INSERT statements only */
1467   TriggerStep *pNext;  /* Next in the link-list */
1468   TriggerStep *pLast;  /* Last element in link-list. Valid for 1st elem only */
1469 };
1470 
1471 /*
1472  * An instance of struct TriggerStack stores information required during code
1473  * generation of a single trigger program. While the trigger program is being
1474  * coded, its associated TriggerStack instance is pointed to by the
1475  * "pTriggerStack" member of the Parse structure.
1476  *
1477  * The pTab member points to the table that triggers are being coded on. The
1478  * newIdx member contains the index of the vdbe cursor that points at the temp
1479  * table that stores the new.* references. If new.* references are not valid
1480  * for the trigger being coded (for example an ON DELETE trigger), then newIdx
1481  * is set to -1. The oldIdx member is analogous to newIdx, for old.* references.
1482  *
1483  * The ON CONFLICT policy to be used for the trigger program steps is stored
1484  * as the orconf member. If this is OE_Default, then the ON CONFLICT clause
1485  * specified for individual triggers steps is used.
1486  *
1487  * struct TriggerStack has a "pNext" member, to allow linked lists to be
1488  * constructed. When coding nested triggers (triggers fired by other triggers)
1489  * each nested trigger stores its parent trigger's TriggerStack as the "pNext"
1490  * pointer. Once the nested trigger has been coded, the pNext value is restored
1491  * to the pTriggerStack member of the Parse stucture and coding of the parent
1492  * trigger continues.
1493  *
1494  * Before a nested trigger is coded, the linked list pointed to by the
1495  * pTriggerStack is scanned to ensure that the trigger is not about to be coded
1496  * recursively. If this condition is detected, the nested trigger is not coded.
1497  */
1498 struct TriggerStack {
1499   Table *pTab;         /* Table that triggers are currently being coded on */
1500   int newIdx;          /* Index of vdbe cursor to "new" temp table */
1501   int oldIdx;          /* Index of vdbe cursor to "old" temp table */
1502   int orconf;          /* Current orconf policy */
1503   int ignoreJump;      /* where to jump to for a RAISE(IGNORE) */
1504   Trigger *pTrigger;   /* The trigger currently being coded */
1505   TriggerStack *pNext; /* Next trigger down on the trigger stack */
1506 };
1507 
1508 /*
1509 ** The following structure contains information used by the sqliteFix...
1510 ** routines as they walk the parse tree to make database references
1511 ** explicit.
1512 */
1513 typedef struct DbFixer DbFixer;
1514 struct DbFixer {
1515   Parse *pParse;      /* The parsing context.  Error messages written here */
1516   const char *zDb;    /* Make sure all objects are contained in this database */
1517   const char *zType;  /* Type of the container - used for error messages */
1518   const Token *pName; /* Name of the container - used for error messages */
1519 };
1520 
1521 /*
1522 ** A pointer to this structure is used to communicate information
1523 ** from sqlite3Init and OP_ParseSchema into the sqlite3InitCallback.
1524 */
1525 typedef struct {
1526   sqlite3 *db;        /* The database being initialized */
1527   int iDb;            /* 0 for main database.  1 for TEMP, 2.. for ATTACHed */
1528   char **pzErrMsg;    /* Error message stored here */
1529   int rc;             /* Result code stored here */
1530 } InitData;
1531 
1532 /*
1533  * This global flag is set for performance testing of triggers. When it is set
1534  * SQLite will perform the overhead of building new and old trigger references
1535  * even when no triggers exist
1536  */
1537 extern int sqlite3_always_code_trigger_setup;
1538 
1539 /*
1540 ** The SQLITE_CORRUPT_BKPT macro can be either a constant (for production
1541 ** builds) or a function call (for debugging).  If it is a function call,
1542 ** it allows the operator to set a breakpoint at the spot where database
1543 ** corruption is first detected.
1544 */
1545 #ifdef SQLITE_DEBUG
1546   extern int sqlite3Corrupt(void);
1547 # define SQLITE_CORRUPT_BKPT sqlite3Corrupt()
1548 #else
1549 # define SQLITE_CORRUPT_BKPT SQLITE_CORRUPT
1550 #endif
1551 
1552 /*
1553 ** Internal function prototypes
1554 */
1555 int sqlite3StrICmp(const char *, const char *);
1556 int sqlite3StrNICmp(const char *, const char *, int);
1557 int sqlite3HashNoCase(const char *, int);
1558 int sqlite3IsNumber(const char*, int*, u8);
1559 int sqlite3Compare(const char *, const char *);
1560 int sqlite3SortCompare(const char *, const char *);
1561 void sqlite3RealToSortable(double r, char *);
1562 
1563 void *sqlite3Malloc(int,int);
1564 void *sqlite3MallocRaw(int,int);
1565 void sqlite3Free(void*);
1566 void *sqlite3Realloc(void*,int);
1567 char *sqlite3StrDup(const char*);
1568 char *sqlite3StrNDup(const char*, int);
1569 # define sqlite3CheckMemory(a,b)
1570 void sqlite3ReallocOrFree(void**,int);
1571 void sqlite3FreeX(void*);
1572 void *sqlite3MallocX(int);
1573 int sqlite3AllocSize(void *);
1574 
1575 char *sqlite3MPrintf(const char*, ...);
1576 char *sqlite3VMPrintf(const char*, va_list);
1577 void sqlite3DebugPrintf(const char*, ...);
1578 void *sqlite3TextToPtr(const char*);
1579 void sqlite3SetString(char **, ...);
1580 void sqlite3ErrorMsg(Parse*, const char*, ...);
1581 void sqlite3ErrorClear(Parse*);
1582 void sqlite3Dequote(char*);
1583 void sqlite3DequoteExpr(Expr*);
1584 int sqlite3KeywordCode(const unsigned char*, int);
1585 int sqlite3RunParser(Parse*, const char*, char **);
1586 void sqlite3FinishCoding(Parse*);
1587 Expr *sqlite3Expr(int, Expr*, Expr*, const Token*);
1588 Expr *sqlite3ExprOrFree(int, Expr*, Expr*, const Token*);
1589 Expr *sqlite3RegisterExpr(Parse*,Token*);
1590 Expr *sqlite3ExprAnd(Expr*, Expr*);
1591 void sqlite3ExprSpan(Expr*,Token*,Token*);
1592 Expr *sqlite3ExprFunction(ExprList*, Token*);
1593 void sqlite3ExprAssignVarNumber(Parse*, Expr*);
1594 void sqlite3ExprDelete(Expr*);
1595 ExprList *sqlite3ExprListAppend(ExprList*,Expr*,Token*);
1596 void sqlite3ExprListDelete(ExprList*);
1597 int sqlite3Init(sqlite3*, char**);
1598 int sqlite3InitCallback(void*, int, char**, char**);
1599 void sqlite3Pragma(Parse*,Token*,Token*,Token*,int);
1600 void sqlite3ResetInternalSchema(sqlite3*, int);
1601 void sqlite3BeginParse(Parse*,int);
1602 void sqlite3RollbackInternalChanges(sqlite3*);
1603 void sqlite3CommitInternalChanges(sqlite3*);
1604 Table *sqlite3ResultSetOfSelect(Parse*,char*,Select*);
1605 void sqlite3OpenMasterTable(Parse *, int);
1606 void sqlite3StartTable(Parse*,Token*,Token*,int,int,int,int);
1607 void sqlite3AddColumn(Parse*,Token*);
1608 void sqlite3AddNotNull(Parse*, int);
1609 void sqlite3AddPrimaryKey(Parse*, ExprList*, int, int, int);
1610 void sqlite3AddCheckConstraint(Parse*, Expr*);
1611 void sqlite3AddColumnType(Parse*,Token*);
1612 void sqlite3AddDefaultValue(Parse*,Expr*);
1613 void sqlite3AddCollateType(Parse*, const char*, int);
1614 void sqlite3EndTable(Parse*,Token*,Token*,Select*);
1615 
1616 void sqlite3CreateView(Parse*,Token*,Token*,Token*,Select*,int,int);
1617 
1618 #if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
1619   int sqlite3ViewGetColumnNames(Parse*,Table*);
1620 #else
1621 # define sqlite3ViewGetColumnNames(A,B) 0
1622 #endif
1623 
1624 void sqlite3DropTable(Parse*, SrcList*, int, int);
1625 void sqlite3DeleteTable(sqlite3*, Table*);
1626 void sqlite3Insert(Parse*, SrcList*, ExprList*, Select*, IdList*, int);
1627 int sqlite3ArrayAllocate(void**,int,int);
1628 IdList *sqlite3IdListAppend(IdList*, Token*);
1629 int sqlite3IdListIndex(IdList*,const char*);
1630 SrcList *sqlite3SrcListAppend(SrcList*, Token*, Token*);
1631 SrcList *sqlite3SrcListAppendFromTerm(SrcList*, Token*, Token*, Token*,
1632                                       Select*, Expr*, IdList*);
1633 void sqlite3SrcListShiftJoinType(SrcList*);
1634 void sqlite3SrcListAssignCursors(Parse*, SrcList*);
1635 void sqlite3IdListDelete(IdList*);
1636 void sqlite3SrcListDelete(SrcList*);
1637 void sqlite3CreateIndex(Parse*,Token*,Token*,SrcList*,ExprList*,int,Token*,
1638                         Token*, int, int);
1639 void sqlite3DropIndex(Parse*, SrcList*, int);
1640 void sqlite3AddKeyType(Vdbe*, ExprList*);
1641 void sqlite3AddIdxKeyType(Vdbe*, Index*);
1642 int sqlite3Select(Parse*, Select*, int, int, Select*, int, int*, char *aff);
1643 Select *sqlite3SelectNew(ExprList*,SrcList*,Expr*,ExprList*,Expr*,ExprList*,
1644                         int,Expr*,Expr*);
1645 void sqlite3SelectDelete(Select*);
1646 void sqlite3SelectUnbind(Select*);
1647 Table *sqlite3SrcListLookup(Parse*, SrcList*);
1648 int sqlite3IsReadOnly(Parse*, Table*, int);
1649 void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int);
1650 void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
1651 void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
1652 WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, ExprList**);
1653 void sqlite3WhereEnd(WhereInfo*);
1654 void sqlite3ExprCodeGetColumn(Vdbe*, Table*, int, int);
1655 void sqlite3ExprCode(Parse*, Expr*);
1656 void sqlite3ExprCodeAndCache(Parse*, Expr*);
1657 int sqlite3ExprCodeExprList(Parse*, ExprList*);
1658 void sqlite3ExprIfTrue(Parse*, Expr*, int, int);
1659 void sqlite3ExprIfFalse(Parse*, Expr*, int, int);
1660 void sqlite3NextedParse(Parse*, const char*, ...);
1661 Table *sqlite3FindTable(sqlite3*,const char*, const char*);
1662 Table *sqlite3LocateTable(Parse*,const char*, const char*);
1663 Index *sqlite3FindIndex(sqlite3*,const char*, const char*);
1664 void sqlite3UnlinkAndDeleteTable(sqlite3*,int,const char*);
1665 void sqlite3UnlinkAndDeleteIndex(sqlite3*,int,const char*);
1666 void sqlite3Vacuum(Parse*);
1667 int sqlite3RunVacuum(char**, sqlite3*);
1668 char *sqlite3NameFromToken(Token*);
1669 int sqlite3ExprCheck(Parse*, Expr*, int, int*);
1670 int sqlite3ExprCompare(Expr*, Expr*);
1671 int sqliteFuncId(Token*);
1672 int sqlite3ExprResolveNames(NameContext *, Expr *);
1673 int sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);
1674 int sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
1675 Vdbe *sqlite3GetVdbe(Parse*);
1676 Expr *sqlite3CreateIdExpr(const char*);
1677 void sqlite3Randomness(int, void*);
1678 void sqlite3RollbackAll(sqlite3*);
1679 void sqlite3CodeVerifySchema(Parse*, int);
1680 void sqlite3BeginTransaction(Parse*, int);
1681 void sqlite3CommitTransaction(Parse*);
1682 void sqlite3RollbackTransaction(Parse*);
1683 int sqlite3ExprIsConstant(Expr*);
1684 int sqlite3ExprIsConstantOrFunction(Expr*);
1685 int sqlite3ExprIsInteger(Expr*, int*);
1686 int sqlite3IsRowid(const char*);
1687 void sqlite3GenerateRowDelete(sqlite3*, Vdbe*, Table*, int, int);
1688 void sqlite3GenerateRowIndexDelete(Vdbe*, Table*, int, char*);
1689 void sqlite3GenerateIndexKey(Vdbe*, Index*, int);
1690 void sqlite3GenerateConstraintChecks(Parse*,Table*,int,char*,int,int,int,int);
1691 void sqlite3CompleteInsertion(Parse*, Table*, int, char*, int, int, int);
1692 void sqlite3OpenTableAndIndices(Parse*, Table*, int, int);
1693 void sqlite3BeginWriteOperation(Parse*, int, int);
1694 Expr *sqlite3ExprDup(Expr*);
1695 void sqlite3TokenCopy(Token*, Token*);
1696 ExprList *sqlite3ExprListDup(ExprList*);
1697 SrcList *sqlite3SrcListDup(SrcList*);
1698 IdList *sqlite3IdListDup(IdList*);
1699 Select *sqlite3SelectDup(Select*);
1700 FuncDef *sqlite3FindFunction(sqlite3*,const char*,int,int,u8,int);
1701 void sqlite3RegisterBuiltinFunctions(sqlite3*);
1702 void sqlite3RegisterDateTimeFunctions(sqlite3*);
1703 int sqlite3SafetyOn(sqlite3*);
1704 int sqlite3SafetyOff(sqlite3*);
1705 int sqlite3SafetyCheck(sqlite3*);
1706 void sqlite3ChangeCookie(sqlite3*, Vdbe*, int);
1707 
1708 #ifndef SQLITE_OMIT_TRIGGER
1709   void sqlite3BeginTrigger(Parse*, Token*,Token*,int,int,IdList*,SrcList*,
1710                            int,Expr*,int, int);
1711   void sqlite3FinishTrigger(Parse*, TriggerStep*, Token*);
1712   void sqlite3DropTrigger(Parse*, SrcList*, int);
1713   void sqlite3DropTriggerPtr(Parse*, Trigger*);
1714   int sqlite3TriggersExist(Parse*, Table*, int, ExprList*);
1715   int sqlite3CodeRowTrigger(Parse*, int, ExprList*, int, Table *, int, int,
1716                            int, int);
1717   void sqliteViewTriggers(Parse*, Table*, Expr*, int, ExprList*);
1718   void sqlite3DeleteTriggerStep(TriggerStep*);
1719   TriggerStep *sqlite3TriggerSelectStep(Select*);
1720   TriggerStep *sqlite3TriggerInsertStep(Token*, IdList*, ExprList*,Select*,int);
1721   TriggerStep *sqlite3TriggerUpdateStep(Token*, ExprList*, Expr*, int);
1722   TriggerStep *sqlite3TriggerDeleteStep(Token*, Expr*);
1723   void sqlite3DeleteTrigger(Trigger*);
1724   void sqlite3UnlinkAndDeleteTrigger(sqlite3*,int,const char*);
1725 #else
1726 # define sqlite3TriggersExist(A,B,C,D,E,F) 0
1727 # define sqlite3DeleteTrigger(A)
1728 # define sqlite3DropTriggerPtr(A,B)
1729 # define sqlite3UnlinkAndDeleteTrigger(A,B,C)
1730 # define sqlite3CodeRowTrigger(A,B,C,D,E,F,G,H,I) 0
1731 #endif
1732 
1733 int sqlite3JoinType(Parse*, Token*, Token*, Token*);
1734 void sqlite3CreateForeignKey(Parse*, ExprList*, Token*, ExprList*, int);
1735 void sqlite3DeferForeignKey(Parse*, int);
1736 #ifndef SQLITE_OMIT_AUTHORIZATION
1737   void sqlite3AuthRead(Parse*,Expr*,SrcList*);
1738   int sqlite3AuthCheck(Parse*,int, const char*, const char*, const char*);
1739   void sqlite3AuthContextPush(Parse*, AuthContext*, const char*);
1740   void sqlite3AuthContextPop(AuthContext*);
1741 #else
1742 # define sqlite3AuthRead(a,b,c)
1743 # define sqlite3AuthCheck(a,b,c,d,e)    SQLITE_OK
1744 # define sqlite3AuthContextPush(a,b,c)
1745 # define sqlite3AuthContextPop(a)  ((void)(a))
1746 #endif
1747 void sqlite3Attach(Parse*, Expr*, Expr*, Expr*);
1748 void sqlite3Detach(Parse*, Expr*);
1749 int sqlite3BtreeFactory(const sqlite3 *db, const char *zFilename,
1750                        int omitJournal, int nCache, Btree **ppBtree);
1751 int sqlite3FixInit(DbFixer*, Parse*, int, const char*, const Token*);
1752 int sqlite3FixSrcList(DbFixer*, SrcList*);
1753 int sqlite3FixSelect(DbFixer*, Select*);
1754 int sqlite3FixExpr(DbFixer*, Expr*);
1755 int sqlite3FixExprList(DbFixer*, ExprList*);
1756 int sqlite3FixTriggerStep(DbFixer*, TriggerStep*);
1757 int sqlite3AtoF(const char *z, double*);
1758 char *sqlite3_snprintf(int,char*,const char*,...);
1759 int sqlite3GetInt32(const char *, int*);
1760 int sqlite3FitsIn64Bits(const char *);
1761 int sqlite3utf16ByteLen(const void *pData, int nChar);
1762 int sqlite3utf8CharLen(const char *pData, int nByte);
1763 int sqlite3ReadUtf8(const unsigned char *);
1764 int sqlite3PutVarint(unsigned char *, u64);
1765 int sqlite3GetVarint(const unsigned char *, u64 *);
1766 int sqlite3GetVarint32(const unsigned char *, u32 *);
1767 int sqlite3VarintLen(u64 v);
1768 void sqlite3IndexAffinityStr(Vdbe *, Index *);
1769 void sqlite3TableAffinityStr(Vdbe *, Table *);
1770 char sqlite3CompareAffinity(Expr *pExpr, char aff2);
1771 int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity);
1772 char sqlite3ExprAffinity(Expr *pExpr);
1773 int sqlite3atoi64(const char*, i64*);
1774 void sqlite3Error(sqlite3*, int, const char*,...);
1775 void *sqlite3HexToBlob(const char *z);
1776 int sqlite3TwoPartName(Parse *, Token *, Token *, Token **);
1777 const char *sqlite3ErrStr(int);
1778 int sqlite3ReadUniChar(const char *zStr, int *pOffset, u8 *pEnc, int fold);
1779 int sqlite3ReadSchema(Parse *pParse);
1780 CollSeq *sqlite3FindCollSeq(sqlite3*,u8 enc, const char *,int,int);
1781 CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char *zName, int nName);
1782 CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);
1783 Expr *sqlite3ExprSetColl(Parse *pParse, Expr *, Token *);
1784 int sqlite3CheckCollSeq(Parse *, CollSeq *);
1785 int sqlite3CheckIndexCollSeq(Parse *, Index *);
1786 int sqlite3CheckObjectName(Parse *, const char *);
1787 void sqlite3VdbeSetChanges(sqlite3 *, int);
1788 void sqlite3utf16Substr(sqlite3_context *,int,sqlite3_value **);
1789 
1790 const void *sqlite3ValueText(sqlite3_value*, u8);
1791 int sqlite3ValueBytes(sqlite3_value*, u8);
1792 void sqlite3ValueSetStr(sqlite3_value*, int, const void *,u8, void(*)(void*));
1793 void sqlite3ValueFree(sqlite3_value*);
1794 sqlite3_value *sqlite3ValueNew(void);
1795 char *sqlite3utf16to8(const void*, int);
1796 int sqlite3ValueFromExpr(Expr *, u8, u8, sqlite3_value **);
1797 void sqlite3ValueApplyAffinity(sqlite3_value *, u8, u8);
1798 extern const unsigned char sqlite3UpperToLower[];
1799 void sqlite3RootPageMoved(Db*, int, int);
1800 void sqlite3Reindex(Parse*, Token*, Token*);
1801 void sqlite3AlterFunctions(sqlite3*);
1802 void sqlite3AlterRenameTable(Parse*, SrcList*, Token*);
1803 int sqlite3GetToken(const unsigned char *, int *);
1804 void sqlite3NestedParse(Parse*, const char*, ...);
1805 void sqlite3ExpirePreparedStatements(sqlite3*);
1806 void sqlite3CodeSubselect(Parse *, Expr *);
1807 int sqlite3SelectResolve(Parse *, Select *, NameContext *);
1808 void sqlite3ColumnDefault(Vdbe *, Table *, int);
1809 void sqlite3AlterFinishAddColumn(Parse *, Token *);
1810 void sqlite3AlterBeginAddColumn(Parse *, SrcList *);
1811 const char *sqlite3TestErrorName(int);
1812 CollSeq *sqlite3GetCollSeq(sqlite3*, CollSeq *, const char *, int);
1813 char sqlite3AffinityType(const Token*);
1814 void sqlite3Analyze(Parse*, Token*, Token*);
1815 int sqlite3InvokeBusyHandler(BusyHandler*);
1816 int sqlite3FindDb(sqlite3*, Token*);
1817 void sqlite3AnalysisLoad(sqlite3*,int iDB);
1818 void sqlite3DefaultRowEst(Index*);
1819 void sqlite3RegisterLikeFunctions(sqlite3*, int);
1820 int sqlite3IsLikeFunction(sqlite3*,Expr*,int*,char*);
1821 ThreadData *sqlite3ThreadData(void);
1822 const ThreadData *sqlite3ThreadDataReadOnly(void);
1823 void sqlite3ReleaseThreadData(void);
1824 void sqlite3AttachFunctions(sqlite3 *);
1825 void sqlite3MinimumFileFormat(Parse*, int, int);
1826 void sqlite3SchemaFree(void *);
1827 Schema *sqlite3SchemaGet(Btree *);
1828 int sqlite3SchemaToIndex(sqlite3 *db, Schema *);
1829 KeyInfo *sqlite3IndexKeyinfo(Parse *, Index *);
1830 int sqlite3CreateFunc(sqlite3 *, const char *, int, int, void *,
1831   void (*)(sqlite3_context*,int,sqlite3_value **),
1832   void (*)(sqlite3_context*,int,sqlite3_value **), void (*)(sqlite3_context*));
1833 int sqlite3ApiExit(sqlite3 *db, int);
1834 int sqlite3MallocFailed(void);
1835 void sqlite3FailedMalloc(void);
1836 void sqlite3AbortOtherActiveVdbes(sqlite3 *, Vdbe *);
1837 int sqlite3OpenTempDatabase(Parse *);
1838 
1839 #ifndef SQLITE_OMIT_LOAD_EXTENSION
1840   void sqlite3CloseExtensions(sqlite3*);
1841   int sqlite3AutoLoadExtensions(sqlite3*);
1842 #else
1843 # define sqlite3CloseExtensions(X)
1844 # define sqlite3AutoLoadExtensions(X)  SQLITE_OK
1845 #endif
1846 
1847 #ifndef SQLITE_OMIT_SHARED_CACHE
1848   void sqlite3TableLock(Parse *, int, int, u8, const char *);
1849 #else
1850   #define sqlite3TableLock(v,w,x,y,z)
1851 #endif
1852 
1853 #ifdef SQLITE_MEMDEBUG
1854   void sqlite3MallocDisallow(void);
1855   void sqlite3MallocAllow(void);
1856   int sqlite3TestMallocFail(void);
1857 #else
1858   #define sqlite3TestMallocFail() 0
1859   #define sqlite3MallocDisallow()
1860   #define sqlite3MallocAllow()
1861 #endif
1862 
1863 #ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
1864   void *sqlite3ThreadSafeMalloc(int);
1865   void sqlite3ThreadSafeFree(void *);
1866 #else
1867   #define sqlite3ThreadSafeMalloc sqlite3MallocX
1868   #define sqlite3ThreadSafeFree sqlite3FreeX
1869 #endif
1870 
1871 #ifdef SQLITE_OMIT_VIRTUALTABLE
1872 #  define sqlite3VtabClear(X)
1873 #  define sqlite3VtabSync(X,Y) (Y)
1874 #  define sqlite3VtabRollback(X)
1875 #  define sqlite3VtabCommit(X)
1876 #else
1877    void sqlite3VtabClear(Table*);
1878    int sqlite3VtabSync(sqlite3 *db, int rc);
1879    int sqlite3VtabRollback(sqlite3 *db);
1880    int sqlite3VtabCommit(sqlite3 *db);
1881 #endif
1882 void sqlite3VtabLock(sqlite3_vtab*);
1883 void sqlite3VtabUnlock(sqlite3_vtab*);
1884 void sqlite3VtabBeginParse(Parse*, Token*, Token*, Token*);
1885 void sqlite3VtabFinishParse(Parse*, Token*);
1886 void sqlite3VtabArgInit(Parse*);
1887 void sqlite3VtabArgExtend(Parse*, Token*);
1888 int sqlite3VtabCallCreate(sqlite3*, int, const char *, char **);
1889 int sqlite3VtabCallConnect(Parse*, Table*);
1890 int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
1891 int sqlite3VtabBegin(sqlite3 *, sqlite3_vtab *);
1892 FuncDef *sqlite3VtabOverloadFunction(FuncDef*, int nArg, Expr*);
1893 void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
1894 int sqlite3Reprepare(Vdbe*);
1895 
1896 #ifdef SQLITE_SSE
1897 #include "sseInt.h"
1898 #endif
1899 
1900 /*
1901 ** If the SQLITE_ENABLE IOTRACE exists then the global variable
1902 ** sqlite3_io_trace is a pointer to a printf-like routine used to
1903 ** print I/O tracing messages.
1904 */
1905 #ifdef SQLITE_ENABLE_IOTRACE
1906 # define IOTRACE(A)  if( sqlite3_io_trace ){ sqlite3_io_trace A; }
1907   void sqlite3VdbeIOTraceSql(Vdbe*);
1908 #else
1909 # define IOTRACE(A)
1910 # define sqlite3VdbeIOTraceSql(X)
1911 #endif
1912 extern void (*sqlite3_io_trace)(const char*,...);
1913 
1914 #endif
1915