xref: /sqlite-3.40.0/src/main.c (revision b88eaf16)
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 ** Main file for the SQLite library.  The routines in this file
13 ** implement the programmer interface to the library.  Routines in
14 ** other files are for internal use by SQLite and should not be
15 ** accessed by users of the library.
16 */
17 #include "sqliteInt.h"
18 
19 #ifdef SQLITE_ENABLE_FTS3
20 # include "fts3.h"
21 #endif
22 #ifdef SQLITE_ENABLE_RTREE
23 # include "rtree.h"
24 #endif
25 #if defined(SQLITE_ENABLE_ICU) || defined(SQLITE_ENABLE_ICU_COLLATIONS)
26 # include "sqliteicu.h"
27 #endif
28 #ifdef SQLITE_ENABLE_JSON1
29 int sqlite3Json1Init(sqlite3*);
30 #endif
31 #ifdef SQLITE_ENABLE_STMTVTAB
32 int sqlite3StmtVtabInit(sqlite3*);
33 #endif
34 #ifdef SQLITE_ENABLE_FTS5
35 int sqlite3Fts5Init(sqlite3*);
36 #endif
37 
38 #ifndef SQLITE_AMALGAMATION
39 /* IMPLEMENTATION-OF: R-46656-45156 The sqlite3_version[] string constant
40 ** contains the text of SQLITE_VERSION macro.
41 */
42 const char sqlite3_version[] = SQLITE_VERSION;
43 #endif
44 
45 /* IMPLEMENTATION-OF: R-53536-42575 The sqlite3_libversion() function returns
46 ** a pointer to the to the sqlite3_version[] string constant.
47 */
48 const char *sqlite3_libversion(void){ return sqlite3_version; }
49 
50 /* IMPLEMENTATION-OF: R-25063-23286 The sqlite3_sourceid() function returns a
51 ** pointer to a string constant whose value is the same as the
52 ** SQLITE_SOURCE_ID C preprocessor macro. Except if SQLite is built using
53 ** an edited copy of the amalgamation, then the last four characters of
54 ** the hash might be different from SQLITE_SOURCE_ID.
55 */
56 const char *sqlite3_sourceid(void){ return SQLITE_SOURCE_ID; }
57 
58 /* IMPLEMENTATION-OF: R-35210-63508 The sqlite3_libversion_number() function
59 ** returns an integer equal to SQLITE_VERSION_NUMBER.
60 */
61 int sqlite3_libversion_number(void){ return SQLITE_VERSION_NUMBER; }
62 
63 /* IMPLEMENTATION-OF: R-20790-14025 The sqlite3_threadsafe() function returns
64 ** zero if and only if SQLite was compiled with mutexing code omitted due to
65 ** the SQLITE_THREADSAFE compile-time option being set to 0.
66 */
67 int sqlite3_threadsafe(void){ return SQLITE_THREADSAFE; }
68 
69 /*
70 ** When compiling the test fixture or with debugging enabled (on Win32),
71 ** this variable being set to non-zero will cause OSTRACE macros to emit
72 ** extra diagnostic information.
73 */
74 #ifdef SQLITE_HAVE_OS_TRACE
75 # ifndef SQLITE_DEBUG_OS_TRACE
76 #   define SQLITE_DEBUG_OS_TRACE 0
77 # endif
78   int sqlite3OSTrace = SQLITE_DEBUG_OS_TRACE;
79 #endif
80 
81 #if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
82 /*
83 ** If the following function pointer is not NULL and if
84 ** SQLITE_ENABLE_IOTRACE is enabled, then messages describing
85 ** I/O active are written using this function.  These messages
86 ** are intended for debugging activity only.
87 */
88 SQLITE_API void (SQLITE_CDECL *sqlite3IoTrace)(const char*, ...) = 0;
89 #endif
90 
91 /*
92 ** If the following global variable points to a string which is the
93 ** name of a directory, then that directory will be used to store
94 ** temporary files.
95 **
96 ** See also the "PRAGMA temp_store_directory" SQL command.
97 */
98 char *sqlite3_temp_directory = 0;
99 
100 /*
101 ** If the following global variable points to a string which is the
102 ** name of a directory, then that directory will be used to store
103 ** all database files specified with a relative pathname.
104 **
105 ** See also the "PRAGMA data_store_directory" SQL command.
106 */
107 char *sqlite3_data_directory = 0;
108 
109 /*
110 ** Initialize SQLite.
111 **
112 ** This routine must be called to initialize the memory allocation,
113 ** VFS, and mutex subsystems prior to doing any serious work with
114 ** SQLite.  But as long as you do not compile with SQLITE_OMIT_AUTOINIT
115 ** this routine will be called automatically by key routines such as
116 ** sqlite3_open().
117 **
118 ** This routine is a no-op except on its very first call for the process,
119 ** or for the first call after a call to sqlite3_shutdown.
120 **
121 ** The first thread to call this routine runs the initialization to
122 ** completion.  If subsequent threads call this routine before the first
123 ** thread has finished the initialization process, then the subsequent
124 ** threads must block until the first thread finishes with the initialization.
125 **
126 ** The first thread might call this routine recursively.  Recursive
127 ** calls to this routine should not block, of course.  Otherwise the
128 ** initialization process would never complete.
129 **
130 ** Let X be the first thread to enter this routine.  Let Y be some other
131 ** thread.  Then while the initial invocation of this routine by X is
132 ** incomplete, it is required that:
133 **
134 **    *  Calls to this routine from Y must block until the outer-most
135 **       call by X completes.
136 **
137 **    *  Recursive calls to this routine from thread X return immediately
138 **       without blocking.
139 */
140 int sqlite3_initialize(void){
141   MUTEX_LOGIC( sqlite3_mutex *pMaster; )       /* The main static mutex */
142   int rc;                                      /* Result code */
143 #ifdef SQLITE_EXTRA_INIT
144   int bRunExtraInit = 0;                       /* Extra initialization needed */
145 #endif
146 
147 #ifdef SQLITE_OMIT_WSD
148   rc = sqlite3_wsd_init(4096, 24);
149   if( rc!=SQLITE_OK ){
150     return rc;
151   }
152 #endif
153 
154   /* If the following assert() fails on some obscure processor/compiler
155   ** combination, the work-around is to set the correct pointer
156   ** size at compile-time using -DSQLITE_PTRSIZE=n compile-time option */
157   assert( SQLITE_PTRSIZE==sizeof(char*) );
158 
159   /* If SQLite is already completely initialized, then this call
160   ** to sqlite3_initialize() should be a no-op.  But the initialization
161   ** must be complete.  So isInit must not be set until the very end
162   ** of this routine.
163   */
164   if( sqlite3GlobalConfig.isInit ) return SQLITE_OK;
165 
166   /* Make sure the mutex subsystem is initialized.  If unable to
167   ** initialize the mutex subsystem, return early with the error.
168   ** If the system is so sick that we are unable to allocate a mutex,
169   ** there is not much SQLite is going to be able to do.
170   **
171   ** The mutex subsystem must take care of serializing its own
172   ** initialization.
173   */
174   rc = sqlite3MutexInit();
175   if( rc ) return rc;
176 
177   /* Initialize the malloc() system and the recursive pInitMutex mutex.
178   ** This operation is protected by the STATIC_MASTER mutex.  Note that
179   ** MutexAlloc() is called for a static mutex prior to initializing the
180   ** malloc subsystem - this implies that the allocation of a static
181   ** mutex must not require support from the malloc subsystem.
182   */
183   MUTEX_LOGIC( pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
184   sqlite3_mutex_enter(pMaster);
185   sqlite3GlobalConfig.isMutexInit = 1;
186   if( !sqlite3GlobalConfig.isMallocInit ){
187     rc = sqlite3MallocInit();
188   }
189   if( rc==SQLITE_OK ){
190     sqlite3GlobalConfig.isMallocInit = 1;
191     if( !sqlite3GlobalConfig.pInitMutex ){
192       sqlite3GlobalConfig.pInitMutex =
193            sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
194       if( sqlite3GlobalConfig.bCoreMutex && !sqlite3GlobalConfig.pInitMutex ){
195         rc = SQLITE_NOMEM_BKPT;
196       }
197     }
198   }
199   if( rc==SQLITE_OK ){
200     sqlite3GlobalConfig.nRefInitMutex++;
201   }
202   sqlite3_mutex_leave(pMaster);
203 
204   /* If rc is not SQLITE_OK at this point, then either the malloc
205   ** subsystem could not be initialized or the system failed to allocate
206   ** the pInitMutex mutex. Return an error in either case.  */
207   if( rc!=SQLITE_OK ){
208     return rc;
209   }
210 
211   /* Do the rest of the initialization under the recursive mutex so
212   ** that we will be able to handle recursive calls into
213   ** sqlite3_initialize().  The recursive calls normally come through
214   ** sqlite3_os_init() when it invokes sqlite3_vfs_register(), but other
215   ** recursive calls might also be possible.
216   **
217   ** IMPLEMENTATION-OF: R-00140-37445 SQLite automatically serializes calls
218   ** to the xInit method, so the xInit method need not be threadsafe.
219   **
220   ** The following mutex is what serializes access to the appdef pcache xInit
221   ** methods.  The sqlite3_pcache_methods.xInit() all is embedded in the
222   ** call to sqlite3PcacheInitialize().
223   */
224   sqlite3_mutex_enter(sqlite3GlobalConfig.pInitMutex);
225   if( sqlite3GlobalConfig.isInit==0 && sqlite3GlobalConfig.inProgress==0 ){
226     sqlite3GlobalConfig.inProgress = 1;
227 #ifdef SQLITE_ENABLE_SQLLOG
228     {
229       extern void sqlite3_init_sqllog(void);
230       sqlite3_init_sqllog();
231     }
232 #endif
233     memset(&sqlite3BuiltinFunctions, 0, sizeof(sqlite3BuiltinFunctions));
234     sqlite3RegisterBuiltinFunctions();
235     if( sqlite3GlobalConfig.isPCacheInit==0 ){
236       rc = sqlite3PcacheInitialize();
237     }
238     if( rc==SQLITE_OK ){
239       sqlite3GlobalConfig.isPCacheInit = 1;
240       rc = sqlite3OsInit();
241     }
242 #ifdef SQLITE_ENABLE_DESERIALIZE
243     if( rc==SQLITE_OK ){
244       rc = sqlite3MemdbInit();
245     }
246 #endif
247     if( rc==SQLITE_OK ){
248       sqlite3PCacheBufferSetup( sqlite3GlobalConfig.pPage,
249           sqlite3GlobalConfig.szPage, sqlite3GlobalConfig.nPage);
250       sqlite3GlobalConfig.isInit = 1;
251 #ifdef SQLITE_EXTRA_INIT
252       bRunExtraInit = 1;
253 #endif
254     }
255     sqlite3GlobalConfig.inProgress = 0;
256   }
257   sqlite3_mutex_leave(sqlite3GlobalConfig.pInitMutex);
258 
259   /* Go back under the static mutex and clean up the recursive
260   ** mutex to prevent a resource leak.
261   */
262   sqlite3_mutex_enter(pMaster);
263   sqlite3GlobalConfig.nRefInitMutex--;
264   if( sqlite3GlobalConfig.nRefInitMutex<=0 ){
265     assert( sqlite3GlobalConfig.nRefInitMutex==0 );
266     sqlite3_mutex_free(sqlite3GlobalConfig.pInitMutex);
267     sqlite3GlobalConfig.pInitMutex = 0;
268   }
269   sqlite3_mutex_leave(pMaster);
270 
271   /* The following is just a sanity check to make sure SQLite has
272   ** been compiled correctly.  It is important to run this code, but
273   ** we don't want to run it too often and soak up CPU cycles for no
274   ** reason.  So we run it once during initialization.
275   */
276 #ifndef NDEBUG
277 #ifndef SQLITE_OMIT_FLOATING_POINT
278   /* This section of code's only "output" is via assert() statements. */
279   if( rc==SQLITE_OK ){
280     u64 x = (((u64)1)<<63)-1;
281     double y;
282     assert(sizeof(x)==8);
283     assert(sizeof(x)==sizeof(y));
284     memcpy(&y, &x, 8);
285     assert( sqlite3IsNaN(y) );
286   }
287 #endif
288 #endif
289 
290   /* Do extra initialization steps requested by the SQLITE_EXTRA_INIT
291   ** compile-time option.
292   */
293 #ifdef SQLITE_EXTRA_INIT
294   if( bRunExtraInit ){
295     int SQLITE_EXTRA_INIT(const char*);
296     rc = SQLITE_EXTRA_INIT(0);
297   }
298 #endif
299 
300   return rc;
301 }
302 
303 /*
304 ** Undo the effects of sqlite3_initialize().  Must not be called while
305 ** there are outstanding database connections or memory allocations or
306 ** while any part of SQLite is otherwise in use in any thread.  This
307 ** routine is not threadsafe.  But it is safe to invoke this routine
308 ** on when SQLite is already shut down.  If SQLite is already shut down
309 ** when this routine is invoked, then this routine is a harmless no-op.
310 */
311 int sqlite3_shutdown(void){
312 #ifdef SQLITE_OMIT_WSD
313   int rc = sqlite3_wsd_init(4096, 24);
314   if( rc!=SQLITE_OK ){
315     return rc;
316   }
317 #endif
318 
319   if( sqlite3GlobalConfig.isInit ){
320 #ifdef SQLITE_EXTRA_SHUTDOWN
321     void SQLITE_EXTRA_SHUTDOWN(void);
322     SQLITE_EXTRA_SHUTDOWN();
323 #endif
324     sqlite3_os_end();
325     sqlite3_reset_auto_extension();
326     sqlite3GlobalConfig.isInit = 0;
327   }
328   if( sqlite3GlobalConfig.isPCacheInit ){
329     sqlite3PcacheShutdown();
330     sqlite3GlobalConfig.isPCacheInit = 0;
331   }
332   if( sqlite3GlobalConfig.isMallocInit ){
333     sqlite3MallocEnd();
334     sqlite3GlobalConfig.isMallocInit = 0;
335 
336 #ifndef SQLITE_OMIT_SHUTDOWN_DIRECTORIES
337     /* The heap subsystem has now been shutdown and these values are supposed
338     ** to be NULL or point to memory that was obtained from sqlite3_malloc(),
339     ** which would rely on that heap subsystem; therefore, make sure these
340     ** values cannot refer to heap memory that was just invalidated when the
341     ** heap subsystem was shutdown.  This is only done if the current call to
342     ** this function resulted in the heap subsystem actually being shutdown.
343     */
344     sqlite3_data_directory = 0;
345     sqlite3_temp_directory = 0;
346 #endif
347   }
348   if( sqlite3GlobalConfig.isMutexInit ){
349     sqlite3MutexEnd();
350     sqlite3GlobalConfig.isMutexInit = 0;
351   }
352 
353   return SQLITE_OK;
354 }
355 
356 /*
357 ** This API allows applications to modify the global configuration of
358 ** the SQLite library at run-time.
359 **
360 ** This routine should only be called when there are no outstanding
361 ** database connections or memory allocations.  This routine is not
362 ** threadsafe.  Failure to heed these warnings can lead to unpredictable
363 ** behavior.
364 */
365 int sqlite3_config(int op, ...){
366   va_list ap;
367   int rc = SQLITE_OK;
368 
369   /* sqlite3_config() shall return SQLITE_MISUSE if it is invoked while
370   ** the SQLite library is in use. */
371   if( sqlite3GlobalConfig.isInit ) return SQLITE_MISUSE_BKPT;
372 
373   va_start(ap, op);
374   switch( op ){
375 
376     /* Mutex configuration options are only available in a threadsafe
377     ** compile.
378     */
379 #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0  /* IMP: R-54466-46756 */
380     case SQLITE_CONFIG_SINGLETHREAD: {
381       /* EVIDENCE-OF: R-02748-19096 This option sets the threading mode to
382       ** Single-thread. */
383       sqlite3GlobalConfig.bCoreMutex = 0;  /* Disable mutex on core */
384       sqlite3GlobalConfig.bFullMutex = 0;  /* Disable mutex on connections */
385       break;
386     }
387 #endif
388 #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-20520-54086 */
389     case SQLITE_CONFIG_MULTITHREAD: {
390       /* EVIDENCE-OF: R-14374-42468 This option sets the threading mode to
391       ** Multi-thread. */
392       sqlite3GlobalConfig.bCoreMutex = 1;  /* Enable mutex on core */
393       sqlite3GlobalConfig.bFullMutex = 0;  /* Disable mutex on connections */
394       break;
395     }
396 #endif
397 #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-59593-21810 */
398     case SQLITE_CONFIG_SERIALIZED: {
399       /* EVIDENCE-OF: R-41220-51800 This option sets the threading mode to
400       ** Serialized. */
401       sqlite3GlobalConfig.bCoreMutex = 1;  /* Enable mutex on core */
402       sqlite3GlobalConfig.bFullMutex = 1;  /* Enable mutex on connections */
403       break;
404     }
405 #endif
406 #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-63666-48755 */
407     case SQLITE_CONFIG_MUTEX: {
408       /* Specify an alternative mutex implementation */
409       sqlite3GlobalConfig.mutex = *va_arg(ap, sqlite3_mutex_methods*);
410       break;
411     }
412 #endif
413 #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-14450-37597 */
414     case SQLITE_CONFIG_GETMUTEX: {
415       /* Retrieve the current mutex implementation */
416       *va_arg(ap, sqlite3_mutex_methods*) = sqlite3GlobalConfig.mutex;
417       break;
418     }
419 #endif
420 
421     case SQLITE_CONFIG_MALLOC: {
422       /* EVIDENCE-OF: R-55594-21030 The SQLITE_CONFIG_MALLOC option takes a
423       ** single argument which is a pointer to an instance of the
424       ** sqlite3_mem_methods structure. The argument specifies alternative
425       ** low-level memory allocation routines to be used in place of the memory
426       ** allocation routines built into SQLite. */
427       sqlite3GlobalConfig.m = *va_arg(ap, sqlite3_mem_methods*);
428       break;
429     }
430     case SQLITE_CONFIG_GETMALLOC: {
431       /* EVIDENCE-OF: R-51213-46414 The SQLITE_CONFIG_GETMALLOC option takes a
432       ** single argument which is a pointer to an instance of the
433       ** sqlite3_mem_methods structure. The sqlite3_mem_methods structure is
434       ** filled with the currently defined memory allocation routines. */
435       if( sqlite3GlobalConfig.m.xMalloc==0 ) sqlite3MemSetDefault();
436       *va_arg(ap, sqlite3_mem_methods*) = sqlite3GlobalConfig.m;
437       break;
438     }
439     case SQLITE_CONFIG_MEMSTATUS: {
440       /* EVIDENCE-OF: R-61275-35157 The SQLITE_CONFIG_MEMSTATUS option takes
441       ** single argument of type int, interpreted as a boolean, which enables
442       ** or disables the collection of memory allocation statistics. */
443       sqlite3GlobalConfig.bMemstat = va_arg(ap, int);
444       break;
445     }
446     case SQLITE_CONFIG_SMALL_MALLOC: {
447       sqlite3GlobalConfig.bSmallMalloc = va_arg(ap, int);
448       break;
449     }
450     case SQLITE_CONFIG_PAGECACHE: {
451       /* EVIDENCE-OF: R-18761-36601 There are three arguments to
452       ** SQLITE_CONFIG_PAGECACHE: A pointer to 8-byte aligned memory (pMem),
453       ** the size of each page cache line (sz), and the number of cache lines
454       ** (N). */
455       sqlite3GlobalConfig.pPage = va_arg(ap, void*);
456       sqlite3GlobalConfig.szPage = va_arg(ap, int);
457       sqlite3GlobalConfig.nPage = va_arg(ap, int);
458       break;
459     }
460     case SQLITE_CONFIG_PCACHE_HDRSZ: {
461       /* EVIDENCE-OF: R-39100-27317 The SQLITE_CONFIG_PCACHE_HDRSZ option takes
462       ** a single parameter which is a pointer to an integer and writes into
463       ** that integer the number of extra bytes per page required for each page
464       ** in SQLITE_CONFIG_PAGECACHE. */
465       *va_arg(ap, int*) =
466           sqlite3HeaderSizeBtree() +
467           sqlite3HeaderSizePcache() +
468           sqlite3HeaderSizePcache1();
469       break;
470     }
471 
472     case SQLITE_CONFIG_PCACHE: {
473       /* no-op */
474       break;
475     }
476     case SQLITE_CONFIG_GETPCACHE: {
477       /* now an error */
478       rc = SQLITE_ERROR;
479       break;
480     }
481 
482     case SQLITE_CONFIG_PCACHE2: {
483       /* EVIDENCE-OF: R-63325-48378 The SQLITE_CONFIG_PCACHE2 option takes a
484       ** single argument which is a pointer to an sqlite3_pcache_methods2
485       ** object. This object specifies the interface to a custom page cache
486       ** implementation. */
487       sqlite3GlobalConfig.pcache2 = *va_arg(ap, sqlite3_pcache_methods2*);
488       break;
489     }
490     case SQLITE_CONFIG_GETPCACHE2: {
491       /* EVIDENCE-OF: R-22035-46182 The SQLITE_CONFIG_GETPCACHE2 option takes a
492       ** single argument which is a pointer to an sqlite3_pcache_methods2
493       ** object. SQLite copies of the current page cache implementation into
494       ** that object. */
495       if( sqlite3GlobalConfig.pcache2.xInit==0 ){
496         sqlite3PCacheSetDefault();
497       }
498       *va_arg(ap, sqlite3_pcache_methods2*) = sqlite3GlobalConfig.pcache2;
499       break;
500     }
501 
502 /* EVIDENCE-OF: R-06626-12911 The SQLITE_CONFIG_HEAP option is only
503 ** available if SQLite is compiled with either SQLITE_ENABLE_MEMSYS3 or
504 ** SQLITE_ENABLE_MEMSYS5 and returns SQLITE_ERROR if invoked otherwise. */
505 #if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
506     case SQLITE_CONFIG_HEAP: {
507       /* EVIDENCE-OF: R-19854-42126 There are three arguments to
508       ** SQLITE_CONFIG_HEAP: An 8-byte aligned pointer to the memory, the
509       ** number of bytes in the memory buffer, and the minimum allocation size.
510       */
511       sqlite3GlobalConfig.pHeap = va_arg(ap, void*);
512       sqlite3GlobalConfig.nHeap = va_arg(ap, int);
513       sqlite3GlobalConfig.mnReq = va_arg(ap, int);
514 
515       if( sqlite3GlobalConfig.mnReq<1 ){
516         sqlite3GlobalConfig.mnReq = 1;
517       }else if( sqlite3GlobalConfig.mnReq>(1<<12) ){
518         /* cap min request size at 2^12 */
519         sqlite3GlobalConfig.mnReq = (1<<12);
520       }
521 
522       if( sqlite3GlobalConfig.pHeap==0 ){
523         /* EVIDENCE-OF: R-49920-60189 If the first pointer (the memory pointer)
524         ** is NULL, then SQLite reverts to using its default memory allocator
525         ** (the system malloc() implementation), undoing any prior invocation of
526         ** SQLITE_CONFIG_MALLOC.
527         **
528         ** Setting sqlite3GlobalConfig.m to all zeros will cause malloc to
529         ** revert to its default implementation when sqlite3_initialize() is run
530         */
531         memset(&sqlite3GlobalConfig.m, 0, sizeof(sqlite3GlobalConfig.m));
532       }else{
533         /* EVIDENCE-OF: R-61006-08918 If the memory pointer is not NULL then the
534         ** alternative memory allocator is engaged to handle all of SQLites
535         ** memory allocation needs. */
536 #ifdef SQLITE_ENABLE_MEMSYS3
537         sqlite3GlobalConfig.m = *sqlite3MemGetMemsys3();
538 #endif
539 #ifdef SQLITE_ENABLE_MEMSYS5
540         sqlite3GlobalConfig.m = *sqlite3MemGetMemsys5();
541 #endif
542       }
543       break;
544     }
545 #endif
546 
547     case SQLITE_CONFIG_LOOKASIDE: {
548       sqlite3GlobalConfig.szLookaside = va_arg(ap, int);
549       sqlite3GlobalConfig.nLookaside = va_arg(ap, int);
550       break;
551     }
552 
553     /* Record a pointer to the logger function and its first argument.
554     ** The default is NULL.  Logging is disabled if the function pointer is
555     ** NULL.
556     */
557     case SQLITE_CONFIG_LOG: {
558       /* MSVC is picky about pulling func ptrs from va lists.
559       ** http://support.microsoft.com/kb/47961
560       ** sqlite3GlobalConfig.xLog = va_arg(ap, void(*)(void*,int,const char*));
561       */
562       typedef void(*LOGFUNC_t)(void*,int,const char*);
563       sqlite3GlobalConfig.xLog = va_arg(ap, LOGFUNC_t);
564       sqlite3GlobalConfig.pLogArg = va_arg(ap, void*);
565       break;
566     }
567 
568     /* EVIDENCE-OF: R-55548-33817 The compile-time setting for URI filenames
569     ** can be changed at start-time using the
570     ** sqlite3_config(SQLITE_CONFIG_URI,1) or
571     ** sqlite3_config(SQLITE_CONFIG_URI,0) configuration calls.
572     */
573     case SQLITE_CONFIG_URI: {
574       /* EVIDENCE-OF: R-25451-61125 The SQLITE_CONFIG_URI option takes a single
575       ** argument of type int. If non-zero, then URI handling is globally
576       ** enabled. If the parameter is zero, then URI handling is globally
577       ** disabled. */
578       sqlite3GlobalConfig.bOpenUri = va_arg(ap, int);
579       break;
580     }
581 
582     case SQLITE_CONFIG_COVERING_INDEX_SCAN: {
583       /* EVIDENCE-OF: R-36592-02772 The SQLITE_CONFIG_COVERING_INDEX_SCAN
584       ** option takes a single integer argument which is interpreted as a
585       ** boolean in order to enable or disable the use of covering indices for
586       ** full table scans in the query optimizer. */
587       sqlite3GlobalConfig.bUseCis = va_arg(ap, int);
588       break;
589     }
590 
591 #ifdef SQLITE_ENABLE_SQLLOG
592     case SQLITE_CONFIG_SQLLOG: {
593       typedef void(*SQLLOGFUNC_t)(void*, sqlite3*, const char*, int);
594       sqlite3GlobalConfig.xSqllog = va_arg(ap, SQLLOGFUNC_t);
595       sqlite3GlobalConfig.pSqllogArg = va_arg(ap, void *);
596       break;
597     }
598 #endif
599 
600     case SQLITE_CONFIG_MMAP_SIZE: {
601       /* EVIDENCE-OF: R-58063-38258 SQLITE_CONFIG_MMAP_SIZE takes two 64-bit
602       ** integer (sqlite3_int64) values that are the default mmap size limit
603       ** (the default setting for PRAGMA mmap_size) and the maximum allowed
604       ** mmap size limit. */
605       sqlite3_int64 szMmap = va_arg(ap, sqlite3_int64);
606       sqlite3_int64 mxMmap = va_arg(ap, sqlite3_int64);
607       /* EVIDENCE-OF: R-53367-43190 If either argument to this option is
608       ** negative, then that argument is changed to its compile-time default.
609       **
610       ** EVIDENCE-OF: R-34993-45031 The maximum allowed mmap size will be
611       ** silently truncated if necessary so that it does not exceed the
612       ** compile-time maximum mmap size set by the SQLITE_MAX_MMAP_SIZE
613       ** compile-time option.
614       */
615       if( mxMmap<0 || mxMmap>SQLITE_MAX_MMAP_SIZE ){
616         mxMmap = SQLITE_MAX_MMAP_SIZE;
617       }
618       if( szMmap<0 ) szMmap = SQLITE_DEFAULT_MMAP_SIZE;
619       if( szMmap>mxMmap) szMmap = mxMmap;
620       sqlite3GlobalConfig.mxMmap = mxMmap;
621       sqlite3GlobalConfig.szMmap = szMmap;
622       break;
623     }
624 
625 #if SQLITE_OS_WIN && defined(SQLITE_WIN32_MALLOC) /* IMP: R-04780-55815 */
626     case SQLITE_CONFIG_WIN32_HEAPSIZE: {
627       /* EVIDENCE-OF: R-34926-03360 SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit
628       ** unsigned integer value that specifies the maximum size of the created
629       ** heap. */
630       sqlite3GlobalConfig.nHeap = va_arg(ap, int);
631       break;
632     }
633 #endif
634 
635     case SQLITE_CONFIG_PMASZ: {
636       sqlite3GlobalConfig.szPma = va_arg(ap, unsigned int);
637       break;
638     }
639 
640     case SQLITE_CONFIG_STMTJRNL_SPILL: {
641       sqlite3GlobalConfig.nStmtSpill = va_arg(ap, int);
642       break;
643     }
644 
645 #ifdef SQLITE_ENABLE_SORTER_REFERENCES
646     case SQLITE_CONFIG_SORTERREF_SIZE: {
647       int iVal = va_arg(ap, int);
648       if( iVal<0 ){
649         iVal = SQLITE_DEFAULT_SORTERREF_SIZE;
650       }
651       sqlite3GlobalConfig.szSorterRef = (u32)iVal;
652       break;
653     }
654 #endif /* SQLITE_ENABLE_SORTER_REFERENCES */
655 
656 #ifdef SQLITE_ENABLE_DESERIALIZE
657     case SQLITE_CONFIG_MEMDB_MAXSIZE: {
658       sqlite3GlobalConfig.mxMemdbSize = va_arg(ap, sqlite3_int64);
659       break;
660     }
661 #endif /* SQLITE_ENABLE_DESERIALIZE */
662 
663     default: {
664       rc = SQLITE_ERROR;
665       break;
666     }
667   }
668   va_end(ap);
669   return rc;
670 }
671 
672 /*
673 ** Set up the lookaside buffers for a database connection.
674 ** Return SQLITE_OK on success.
675 ** If lookaside is already active, return SQLITE_BUSY.
676 **
677 ** The sz parameter is the number of bytes in each lookaside slot.
678 ** The cnt parameter is the number of slots.  If pStart is NULL the
679 ** space for the lookaside memory is obtained from sqlite3_malloc().
680 ** If pStart is not NULL then it is sz*cnt bytes of memory to use for
681 ** the lookaside memory.
682 */
683 static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
684 #ifndef SQLITE_OMIT_LOOKASIDE
685   void *pStart;
686 
687   if( sqlite3LookasideUsed(db,0)>0 ){
688     return SQLITE_BUSY;
689   }
690   /* Free any existing lookaside buffer for this handle before
691   ** allocating a new one so we don't have to have space for
692   ** both at the same time.
693   */
694   if( db->lookaside.bMalloced ){
695     sqlite3_free(db->lookaside.pStart);
696   }
697   /* The size of a lookaside slot after ROUNDDOWN8 needs to be larger
698   ** than a pointer to be useful.
699   */
700   sz = ROUNDDOWN8(sz);  /* IMP: R-33038-09382 */
701   if( sz<=(int)sizeof(LookasideSlot*) ) sz = 0;
702   if( cnt<0 ) cnt = 0;
703   if( sz==0 || cnt==0 ){
704     sz = 0;
705     pStart = 0;
706   }else if( pBuf==0 ){
707     sqlite3BeginBenignMalloc();
708     pStart = sqlite3Malloc( sz*(sqlite3_int64)cnt );  /* IMP: R-61949-35727 */
709     sqlite3EndBenignMalloc();
710     if( pStart ) cnt = sqlite3MallocSize(pStart)/sz;
711   }else{
712     pStart = pBuf;
713   }
714   db->lookaside.pStart = pStart;
715   db->lookaside.pInit = 0;
716   db->lookaside.pFree = 0;
717   db->lookaside.sz = (u16)sz;
718   db->lookaside.szTrue = (u16)sz;
719   if( pStart ){
720     int i;
721     LookasideSlot *p;
722     assert( sz > (int)sizeof(LookasideSlot*) );
723     db->lookaside.nSlot = cnt;
724     p = (LookasideSlot*)pStart;
725     for(i=cnt-1; i>=0; i--){
726       p->pNext = db->lookaside.pInit;
727       db->lookaside.pInit = p;
728       p = (LookasideSlot*)&((u8*)p)[sz];
729     }
730     db->lookaside.pEnd = p;
731     db->lookaside.bDisable = 0;
732     db->lookaside.bMalloced = pBuf==0 ?1:0;
733   }else{
734     db->lookaside.pStart = db;
735     db->lookaside.pEnd = db;
736     db->lookaside.bDisable = 1;
737     db->lookaside.sz = 0;
738     db->lookaside.bMalloced = 0;
739     db->lookaside.nSlot = 0;
740   }
741 #endif /* SQLITE_OMIT_LOOKASIDE */
742   return SQLITE_OK;
743 }
744 
745 /*
746 ** Return the mutex associated with a database connection.
747 */
748 sqlite3_mutex *sqlite3_db_mutex(sqlite3 *db){
749 #ifdef SQLITE_ENABLE_API_ARMOR
750   if( !sqlite3SafetyCheckOk(db) ){
751     (void)SQLITE_MISUSE_BKPT;
752     return 0;
753   }
754 #endif
755   return db->mutex;
756 }
757 
758 /*
759 ** Free up as much memory as we can from the given database
760 ** connection.
761 */
762 int sqlite3_db_release_memory(sqlite3 *db){
763   int i;
764 
765 #ifdef SQLITE_ENABLE_API_ARMOR
766   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
767 #endif
768   sqlite3_mutex_enter(db->mutex);
769   sqlite3BtreeEnterAll(db);
770   for(i=0; i<db->nDb; i++){
771     Btree *pBt = db->aDb[i].pBt;
772     if( pBt ){
773       Pager *pPager = sqlite3BtreePager(pBt);
774       sqlite3PagerShrink(pPager);
775     }
776   }
777   sqlite3BtreeLeaveAll(db);
778   sqlite3_mutex_leave(db->mutex);
779   return SQLITE_OK;
780 }
781 
782 /*
783 ** Flush any dirty pages in the pager-cache for any attached database
784 ** to disk.
785 */
786 int sqlite3_db_cacheflush(sqlite3 *db){
787   int i;
788   int rc = SQLITE_OK;
789   int bSeenBusy = 0;
790 
791 #ifdef SQLITE_ENABLE_API_ARMOR
792   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
793 #endif
794   sqlite3_mutex_enter(db->mutex);
795   sqlite3BtreeEnterAll(db);
796   for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
797     Btree *pBt = db->aDb[i].pBt;
798     if( pBt && sqlite3BtreeIsInTrans(pBt) ){
799       Pager *pPager = sqlite3BtreePager(pBt);
800       rc = sqlite3PagerFlush(pPager);
801       if( rc==SQLITE_BUSY ){
802         bSeenBusy = 1;
803         rc = SQLITE_OK;
804       }
805     }
806   }
807   sqlite3BtreeLeaveAll(db);
808   sqlite3_mutex_leave(db->mutex);
809   return ((rc==SQLITE_OK && bSeenBusy) ? SQLITE_BUSY : rc);
810 }
811 
812 /*
813 ** Configuration settings for an individual database connection
814 */
815 int sqlite3_db_config(sqlite3 *db, int op, ...){
816   va_list ap;
817   int rc;
818   va_start(ap, op);
819   switch( op ){
820     case SQLITE_DBCONFIG_MAINDBNAME: {
821       /* IMP: R-06824-28531 */
822       /* IMP: R-36257-52125 */
823       db->aDb[0].zDbSName = va_arg(ap,char*);
824       rc = SQLITE_OK;
825       break;
826     }
827     case SQLITE_DBCONFIG_LOOKASIDE: {
828       void *pBuf = va_arg(ap, void*); /* IMP: R-26835-10964 */
829       int sz = va_arg(ap, int);       /* IMP: R-47871-25994 */
830       int cnt = va_arg(ap, int);      /* IMP: R-04460-53386 */
831       rc = setupLookaside(db, pBuf, sz, cnt);
832       break;
833     }
834     default: {
835       static const struct {
836         int op;      /* The opcode */
837         u32 mask;    /* Mask of the bit in sqlite3.flags to set/clear */
838       } aFlagOp[] = {
839         { SQLITE_DBCONFIG_ENABLE_FKEY,           SQLITE_ForeignKeys    },
840         { SQLITE_DBCONFIG_ENABLE_TRIGGER,        SQLITE_EnableTrigger  },
841         { SQLITE_DBCONFIG_ENABLE_VIEW,           SQLITE_EnableView     },
842         { SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER, SQLITE_Fts3Tokenizer  },
843         { SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, SQLITE_LoadExtension  },
844         { SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE,      SQLITE_NoCkptOnClose  },
845         { SQLITE_DBCONFIG_ENABLE_QPSG,           SQLITE_EnableQPSG     },
846         { SQLITE_DBCONFIG_TRIGGER_EQP,           SQLITE_TriggerEQP     },
847         { SQLITE_DBCONFIG_RESET_DATABASE,        SQLITE_ResetDatabase  },
848         { SQLITE_DBCONFIG_DEFENSIVE,             SQLITE_Defensive      },
849         { SQLITE_DBCONFIG_WRITABLE_SCHEMA,       SQLITE_WriteSchema|
850                                                  SQLITE_NoSchemaError  },
851         { SQLITE_DBCONFIG_LEGACY_ALTER_TABLE,    SQLITE_LegacyAlter    },
852         { SQLITE_DBCONFIG_DQS_DDL,               SQLITE_DqsDDL         },
853         { SQLITE_DBCONFIG_DQS_DML,               SQLITE_DqsDML         },
854         { SQLITE_DBCONFIG_LEGACY_FILE_FORMAT,    SQLITE_LegacyFileFmt  },
855       };
856       unsigned int i;
857       rc = SQLITE_ERROR; /* IMP: R-42790-23372 */
858       for(i=0; i<ArraySize(aFlagOp); i++){
859         if( aFlagOp[i].op==op ){
860           int onoff = va_arg(ap, int);
861           int *pRes = va_arg(ap, int*);
862           u64 oldFlags = db->flags;
863           if( onoff>0 ){
864             db->flags |= aFlagOp[i].mask;
865           }else if( onoff==0 ){
866             db->flags &= ~(u64)aFlagOp[i].mask;
867           }
868           if( oldFlags!=db->flags ){
869             sqlite3ExpirePreparedStatements(db, 0);
870           }
871           if( pRes ){
872             *pRes = (db->flags & aFlagOp[i].mask)!=0;
873           }
874           rc = SQLITE_OK;
875           break;
876         }
877       }
878       break;
879     }
880   }
881   va_end(ap);
882   return rc;
883 }
884 
885 /*
886 ** This is the default collating function named "BINARY" which is always
887 ** available.
888 */
889 static int binCollFunc(
890   void *NotUsed,
891   int nKey1, const void *pKey1,
892   int nKey2, const void *pKey2
893 ){
894   int rc, n;
895   UNUSED_PARAMETER(NotUsed);
896   n = nKey1<nKey2 ? nKey1 : nKey2;
897   /* EVIDENCE-OF: R-65033-28449 The built-in BINARY collation compares
898   ** strings byte by byte using the memcmp() function from the standard C
899   ** library. */
900   assert( pKey1 && pKey2 );
901   rc = memcmp(pKey1, pKey2, n);
902   if( rc==0 ){
903     rc = nKey1 - nKey2;
904   }
905   return rc;
906 }
907 
908 /*
909 ** This is the collating function named "RTRIM" which is always
910 ** available.  Ignore trailing spaces.
911 */
912 static int rtrimCollFunc(
913   void *pUser,
914   int nKey1, const void *pKey1,
915   int nKey2, const void *pKey2
916 ){
917   const u8 *pK1 = (const u8*)pKey1;
918   const u8 *pK2 = (const u8*)pKey2;
919   while( nKey1 && pK1[nKey1-1]==' ' ) nKey1--;
920   while( nKey2 && pK2[nKey2-1]==' ' ) nKey2--;
921   return binCollFunc(pUser, nKey1, pKey1, nKey2, pKey2);
922 }
923 
924 /*
925 ** Return true if CollSeq is the default built-in BINARY.
926 */
927 int sqlite3IsBinary(const CollSeq *p){
928   assert( p==0 || p->xCmp!=binCollFunc || strcmp(p->zName,"BINARY")==0 );
929   return p==0 || p->xCmp==binCollFunc;
930 }
931 
932 /*
933 ** Another built-in collating sequence: NOCASE.
934 **
935 ** This collating sequence is intended to be used for "case independent
936 ** comparison". SQLite's knowledge of upper and lower case equivalents
937 ** extends only to the 26 characters used in the English language.
938 **
939 ** At the moment there is only a UTF-8 implementation.
940 */
941 static int nocaseCollatingFunc(
942   void *NotUsed,
943   int nKey1, const void *pKey1,
944   int nKey2, const void *pKey2
945 ){
946   int r = sqlite3StrNICmp(
947       (const char *)pKey1, (const char *)pKey2, (nKey1<nKey2)?nKey1:nKey2);
948   UNUSED_PARAMETER(NotUsed);
949   if( 0==r ){
950     r = nKey1-nKey2;
951   }
952   return r;
953 }
954 
955 /*
956 ** Return the ROWID of the most recent insert
957 */
958 sqlite_int64 sqlite3_last_insert_rowid(sqlite3 *db){
959 #ifdef SQLITE_ENABLE_API_ARMOR
960   if( !sqlite3SafetyCheckOk(db) ){
961     (void)SQLITE_MISUSE_BKPT;
962     return 0;
963   }
964 #endif
965   return db->lastRowid;
966 }
967 
968 /*
969 ** Set the value returned by the sqlite3_last_insert_rowid() API function.
970 */
971 void sqlite3_set_last_insert_rowid(sqlite3 *db, sqlite3_int64 iRowid){
972 #ifdef SQLITE_ENABLE_API_ARMOR
973   if( !sqlite3SafetyCheckOk(db) ){
974     (void)SQLITE_MISUSE_BKPT;
975     return;
976   }
977 #endif
978   sqlite3_mutex_enter(db->mutex);
979   db->lastRowid = iRowid;
980   sqlite3_mutex_leave(db->mutex);
981 }
982 
983 /*
984 ** Return the number of changes in the most recent call to sqlite3_exec().
985 */
986 int sqlite3_changes(sqlite3 *db){
987 #ifdef SQLITE_ENABLE_API_ARMOR
988   if( !sqlite3SafetyCheckOk(db) ){
989     (void)SQLITE_MISUSE_BKPT;
990     return 0;
991   }
992 #endif
993   return db->nChange;
994 }
995 
996 /*
997 ** Return the number of changes since the database handle was opened.
998 */
999 int sqlite3_total_changes(sqlite3 *db){
1000 #ifdef SQLITE_ENABLE_API_ARMOR
1001   if( !sqlite3SafetyCheckOk(db) ){
1002     (void)SQLITE_MISUSE_BKPT;
1003     return 0;
1004   }
1005 #endif
1006   return db->nTotalChange;
1007 }
1008 
1009 /*
1010 ** Close all open savepoints. This function only manipulates fields of the
1011 ** database handle object, it does not close any savepoints that may be open
1012 ** at the b-tree/pager level.
1013 */
1014 void sqlite3CloseSavepoints(sqlite3 *db){
1015   while( db->pSavepoint ){
1016     Savepoint *pTmp = db->pSavepoint;
1017     db->pSavepoint = pTmp->pNext;
1018     sqlite3DbFree(db, pTmp);
1019   }
1020   db->nSavepoint = 0;
1021   db->nStatement = 0;
1022   db->isTransactionSavepoint = 0;
1023 }
1024 
1025 /*
1026 ** Invoke the destructor function associated with FuncDef p, if any. Except,
1027 ** if this is not the last copy of the function, do not invoke it. Multiple
1028 ** copies of a single function are created when create_function() is called
1029 ** with SQLITE_ANY as the encoding.
1030 */
1031 static void functionDestroy(sqlite3 *db, FuncDef *p){
1032   FuncDestructor *pDestructor = p->u.pDestructor;
1033   if( pDestructor ){
1034     pDestructor->nRef--;
1035     if( pDestructor->nRef==0 ){
1036       pDestructor->xDestroy(pDestructor->pUserData);
1037       sqlite3DbFree(db, pDestructor);
1038     }
1039   }
1040 }
1041 
1042 /*
1043 ** Disconnect all sqlite3_vtab objects that belong to database connection
1044 ** db. This is called when db is being closed.
1045 */
1046 static void disconnectAllVtab(sqlite3 *db){
1047 #ifndef SQLITE_OMIT_VIRTUALTABLE
1048   int i;
1049   HashElem *p;
1050   sqlite3BtreeEnterAll(db);
1051   for(i=0; i<db->nDb; i++){
1052     Schema *pSchema = db->aDb[i].pSchema;
1053     if( pSchema ){
1054       for(p=sqliteHashFirst(&pSchema->tblHash); p; p=sqliteHashNext(p)){
1055         Table *pTab = (Table *)sqliteHashData(p);
1056         if( IsVirtual(pTab) ) sqlite3VtabDisconnect(db, pTab);
1057       }
1058     }
1059   }
1060   for(p=sqliteHashFirst(&db->aModule); p; p=sqliteHashNext(p)){
1061     Module *pMod = (Module *)sqliteHashData(p);
1062     if( pMod->pEpoTab ){
1063       sqlite3VtabDisconnect(db, pMod->pEpoTab);
1064     }
1065   }
1066   sqlite3VtabUnlockList(db);
1067   sqlite3BtreeLeaveAll(db);
1068 #else
1069   UNUSED_PARAMETER(db);
1070 #endif
1071 }
1072 
1073 /*
1074 ** Return TRUE if database connection db has unfinalized prepared
1075 ** statements or unfinished sqlite3_backup objects.
1076 */
1077 static int connectionIsBusy(sqlite3 *db){
1078   int j;
1079   assert( sqlite3_mutex_held(db->mutex) );
1080   if( db->pVdbe ) return 1;
1081   for(j=0; j<db->nDb; j++){
1082     Btree *pBt = db->aDb[j].pBt;
1083     if( pBt && sqlite3BtreeIsInBackup(pBt) ) return 1;
1084   }
1085   return 0;
1086 }
1087 
1088 /*
1089 ** Close an existing SQLite database
1090 */
1091 static int sqlite3Close(sqlite3 *db, int forceZombie){
1092   if( !db ){
1093     /* EVIDENCE-OF: R-63257-11740 Calling sqlite3_close() or
1094     ** sqlite3_close_v2() with a NULL pointer argument is a harmless no-op. */
1095     return SQLITE_OK;
1096   }
1097   if( !sqlite3SafetyCheckSickOrOk(db) ){
1098     return SQLITE_MISUSE_BKPT;
1099   }
1100   sqlite3_mutex_enter(db->mutex);
1101   if( db->mTrace & SQLITE_TRACE_CLOSE ){
1102     db->xTrace(SQLITE_TRACE_CLOSE, db->pTraceArg, db, 0);
1103   }
1104 
1105   /* Force xDisconnect calls on all virtual tables */
1106   disconnectAllVtab(db);
1107 
1108   /* If a transaction is open, the disconnectAllVtab() call above
1109   ** will not have called the xDisconnect() method on any virtual
1110   ** tables in the db->aVTrans[] array. The following sqlite3VtabRollback()
1111   ** call will do so. We need to do this before the check for active
1112   ** SQL statements below, as the v-table implementation may be storing
1113   ** some prepared statements internally.
1114   */
1115   sqlite3VtabRollback(db);
1116 
1117   /* Legacy behavior (sqlite3_close() behavior) is to return
1118   ** SQLITE_BUSY if the connection can not be closed immediately.
1119   */
1120   if( !forceZombie && connectionIsBusy(db) ){
1121     sqlite3ErrorWithMsg(db, SQLITE_BUSY, "unable to close due to unfinalized "
1122        "statements or unfinished backups");
1123     sqlite3_mutex_leave(db->mutex);
1124     return SQLITE_BUSY;
1125   }
1126 
1127 #ifdef SQLITE_ENABLE_SQLLOG
1128   if( sqlite3GlobalConfig.xSqllog ){
1129     /* Closing the handle. Fourth parameter is passed the value 2. */
1130     sqlite3GlobalConfig.xSqllog(sqlite3GlobalConfig.pSqllogArg, db, 0, 2);
1131   }
1132 #endif
1133 
1134   /* Convert the connection into a zombie and then close it.
1135   */
1136   db->magic = SQLITE_MAGIC_ZOMBIE;
1137   sqlite3LeaveMutexAndCloseZombie(db);
1138   return SQLITE_OK;
1139 }
1140 
1141 /*
1142 ** Two variations on the public interface for closing a database
1143 ** connection. The sqlite3_close() version returns SQLITE_BUSY and
1144 ** leaves the connection option if there are unfinalized prepared
1145 ** statements or unfinished sqlite3_backups.  The sqlite3_close_v2()
1146 ** version forces the connection to become a zombie if there are
1147 ** unclosed resources, and arranges for deallocation when the last
1148 ** prepare statement or sqlite3_backup closes.
1149 */
1150 int sqlite3_close(sqlite3 *db){ return sqlite3Close(db,0); }
1151 int sqlite3_close_v2(sqlite3 *db){ return sqlite3Close(db,1); }
1152 
1153 
1154 /*
1155 ** Close the mutex on database connection db.
1156 **
1157 ** Furthermore, if database connection db is a zombie (meaning that there
1158 ** has been a prior call to sqlite3_close(db) or sqlite3_close_v2(db)) and
1159 ** every sqlite3_stmt has now been finalized and every sqlite3_backup has
1160 ** finished, then free all resources.
1161 */
1162 void sqlite3LeaveMutexAndCloseZombie(sqlite3 *db){
1163   HashElem *i;                    /* Hash table iterator */
1164   int j;
1165 
1166   /* If there are outstanding sqlite3_stmt or sqlite3_backup objects
1167   ** or if the connection has not yet been closed by sqlite3_close_v2(),
1168   ** then just leave the mutex and return.
1169   */
1170   if( db->magic!=SQLITE_MAGIC_ZOMBIE || connectionIsBusy(db) ){
1171     sqlite3_mutex_leave(db->mutex);
1172     return;
1173   }
1174 
1175   /* If we reach this point, it means that the database connection has
1176   ** closed all sqlite3_stmt and sqlite3_backup objects and has been
1177   ** passed to sqlite3_close (meaning that it is a zombie).  Therefore,
1178   ** go ahead and free all resources.
1179   */
1180 
1181   /* If a transaction is open, roll it back. This also ensures that if
1182   ** any database schemas have been modified by an uncommitted transaction
1183   ** they are reset. And that the required b-tree mutex is held to make
1184   ** the pager rollback and schema reset an atomic operation. */
1185   sqlite3RollbackAll(db, SQLITE_OK);
1186 
1187   /* Free any outstanding Savepoint structures. */
1188   sqlite3CloseSavepoints(db);
1189 
1190   /* Close all database connections */
1191   for(j=0; j<db->nDb; j++){
1192     struct Db *pDb = &db->aDb[j];
1193     if( pDb->pBt ){
1194       sqlite3BtreeClose(pDb->pBt);
1195       pDb->pBt = 0;
1196       if( j!=1 ){
1197         pDb->pSchema = 0;
1198       }
1199     }
1200   }
1201   /* Clear the TEMP schema separately and last */
1202   if( db->aDb[1].pSchema ){
1203     sqlite3SchemaClear(db->aDb[1].pSchema);
1204   }
1205   sqlite3VtabUnlockList(db);
1206 
1207   /* Free up the array of auxiliary databases */
1208   sqlite3CollapseDatabaseArray(db);
1209   assert( db->nDb<=2 );
1210   assert( db->aDb==db->aDbStatic );
1211 
1212   /* Tell the code in notify.c that the connection no longer holds any
1213   ** locks and does not require any further unlock-notify callbacks.
1214   */
1215   sqlite3ConnectionClosed(db);
1216 
1217   for(i=sqliteHashFirst(&db->aFunc); i; i=sqliteHashNext(i)){
1218     FuncDef *pNext, *p;
1219     p = sqliteHashData(i);
1220     do{
1221       functionDestroy(db, p);
1222       pNext = p->pNext;
1223       sqlite3DbFree(db, p);
1224       p = pNext;
1225     }while( p );
1226   }
1227   sqlite3HashClear(&db->aFunc);
1228   for(i=sqliteHashFirst(&db->aCollSeq); i; i=sqliteHashNext(i)){
1229     CollSeq *pColl = (CollSeq *)sqliteHashData(i);
1230     /* Invoke any destructors registered for collation sequence user data. */
1231     for(j=0; j<3; j++){
1232       if( pColl[j].xDel ){
1233         pColl[j].xDel(pColl[j].pUser);
1234       }
1235     }
1236     sqlite3DbFree(db, pColl);
1237   }
1238   sqlite3HashClear(&db->aCollSeq);
1239 #ifndef SQLITE_OMIT_VIRTUALTABLE
1240   for(i=sqliteHashFirst(&db->aModule); i; i=sqliteHashNext(i)){
1241     Module *pMod = (Module *)sqliteHashData(i);
1242     sqlite3VtabEponymousTableClear(db, pMod);
1243     sqlite3VtabModuleUnref(db, pMod);
1244   }
1245   sqlite3HashClear(&db->aModule);
1246 #endif
1247 
1248   sqlite3Error(db, SQLITE_OK); /* Deallocates any cached error strings. */
1249   sqlite3ValueFree(db->pErr);
1250   sqlite3CloseExtensions(db);
1251 #if SQLITE_USER_AUTHENTICATION
1252   sqlite3_free(db->auth.zAuthUser);
1253   sqlite3_free(db->auth.zAuthPW);
1254 #endif
1255 
1256   db->magic = SQLITE_MAGIC_ERROR;
1257 
1258   /* The temp-database schema is allocated differently from the other schema
1259   ** objects (using sqliteMalloc() directly, instead of sqlite3BtreeSchema()).
1260   ** So it needs to be freed here. Todo: Why not roll the temp schema into
1261   ** the same sqliteMalloc() as the one that allocates the database
1262   ** structure?
1263   */
1264   sqlite3DbFree(db, db->aDb[1].pSchema);
1265   sqlite3_mutex_leave(db->mutex);
1266   db->magic = SQLITE_MAGIC_CLOSED;
1267   sqlite3_mutex_free(db->mutex);
1268   assert( sqlite3LookasideUsed(db,0)==0 );
1269   if( db->lookaside.bMalloced ){
1270     sqlite3_free(db->lookaside.pStart);
1271   }
1272   sqlite3_free(db);
1273 }
1274 
1275 /*
1276 ** Rollback all database files.  If tripCode is not SQLITE_OK, then
1277 ** any write cursors are invalidated ("tripped" - as in "tripping a circuit
1278 ** breaker") and made to return tripCode if there are any further
1279 ** attempts to use that cursor.  Read cursors remain open and valid
1280 ** but are "saved" in case the table pages are moved around.
1281 */
1282 void sqlite3RollbackAll(sqlite3 *db, int tripCode){
1283   int i;
1284   int inTrans = 0;
1285   int schemaChange;
1286   assert( sqlite3_mutex_held(db->mutex) );
1287   sqlite3BeginBenignMalloc();
1288 
1289   /* Obtain all b-tree mutexes before making any calls to BtreeRollback().
1290   ** This is important in case the transaction being rolled back has
1291   ** modified the database schema. If the b-tree mutexes are not taken
1292   ** here, then another shared-cache connection might sneak in between
1293   ** the database rollback and schema reset, which can cause false
1294   ** corruption reports in some cases.  */
1295   sqlite3BtreeEnterAll(db);
1296   schemaChange = (db->mDbFlags & DBFLAG_SchemaChange)!=0 && db->init.busy==0;
1297 
1298   for(i=0; i<db->nDb; i++){
1299     Btree *p = db->aDb[i].pBt;
1300     if( p ){
1301       if( sqlite3BtreeIsInTrans(p) ){
1302         inTrans = 1;
1303       }
1304       sqlite3BtreeRollback(p, tripCode, !schemaChange);
1305     }
1306   }
1307   sqlite3VtabRollback(db);
1308   sqlite3EndBenignMalloc();
1309 
1310   if( schemaChange ){
1311     sqlite3ExpirePreparedStatements(db, 0);
1312     sqlite3ResetAllSchemasOfConnection(db);
1313   }
1314   sqlite3BtreeLeaveAll(db);
1315 
1316   /* Any deferred constraint violations have now been resolved. */
1317   db->nDeferredCons = 0;
1318   db->nDeferredImmCons = 0;
1319   db->flags &= ~(u64)SQLITE_DeferFKs;
1320 
1321   /* If one has been configured, invoke the rollback-hook callback */
1322   if( db->xRollbackCallback && (inTrans || !db->autoCommit) ){
1323     db->xRollbackCallback(db->pRollbackArg);
1324   }
1325 }
1326 
1327 /*
1328 ** Return a static string containing the name corresponding to the error code
1329 ** specified in the argument.
1330 */
1331 #if defined(SQLITE_NEED_ERR_NAME)
1332 const char *sqlite3ErrName(int rc){
1333   const char *zName = 0;
1334   int i, origRc = rc;
1335   for(i=0; i<2 && zName==0; i++, rc &= 0xff){
1336     switch( rc ){
1337       case SQLITE_OK:                 zName = "SQLITE_OK";                break;
1338       case SQLITE_ERROR:              zName = "SQLITE_ERROR";             break;
1339       case SQLITE_ERROR_SNAPSHOT:     zName = "SQLITE_ERROR_SNAPSHOT";    break;
1340       case SQLITE_INTERNAL:           zName = "SQLITE_INTERNAL";          break;
1341       case SQLITE_PERM:               zName = "SQLITE_PERM";              break;
1342       case SQLITE_ABORT:              zName = "SQLITE_ABORT";             break;
1343       case SQLITE_ABORT_ROLLBACK:     zName = "SQLITE_ABORT_ROLLBACK";    break;
1344       case SQLITE_BUSY:               zName = "SQLITE_BUSY";              break;
1345       case SQLITE_BUSY_RECOVERY:      zName = "SQLITE_BUSY_RECOVERY";     break;
1346       case SQLITE_BUSY_SNAPSHOT:      zName = "SQLITE_BUSY_SNAPSHOT";     break;
1347       case SQLITE_LOCKED:             zName = "SQLITE_LOCKED";            break;
1348       case SQLITE_LOCKED_SHAREDCACHE: zName = "SQLITE_LOCKED_SHAREDCACHE";break;
1349       case SQLITE_NOMEM:              zName = "SQLITE_NOMEM";             break;
1350       case SQLITE_READONLY:           zName = "SQLITE_READONLY";          break;
1351       case SQLITE_READONLY_RECOVERY:  zName = "SQLITE_READONLY_RECOVERY"; break;
1352       case SQLITE_READONLY_CANTINIT:  zName = "SQLITE_READONLY_CANTINIT"; break;
1353       case SQLITE_READONLY_ROLLBACK:  zName = "SQLITE_READONLY_ROLLBACK"; break;
1354       case SQLITE_READONLY_DBMOVED:   zName = "SQLITE_READONLY_DBMOVED";  break;
1355       case SQLITE_READONLY_DIRECTORY: zName = "SQLITE_READONLY_DIRECTORY";break;
1356       case SQLITE_INTERRUPT:          zName = "SQLITE_INTERRUPT";         break;
1357       case SQLITE_IOERR:              zName = "SQLITE_IOERR";             break;
1358       case SQLITE_IOERR_READ:         zName = "SQLITE_IOERR_READ";        break;
1359       case SQLITE_IOERR_SHORT_READ:   zName = "SQLITE_IOERR_SHORT_READ";  break;
1360       case SQLITE_IOERR_WRITE:        zName = "SQLITE_IOERR_WRITE";       break;
1361       case SQLITE_IOERR_FSYNC:        zName = "SQLITE_IOERR_FSYNC";       break;
1362       case SQLITE_IOERR_DIR_FSYNC:    zName = "SQLITE_IOERR_DIR_FSYNC";   break;
1363       case SQLITE_IOERR_TRUNCATE:     zName = "SQLITE_IOERR_TRUNCATE";    break;
1364       case SQLITE_IOERR_FSTAT:        zName = "SQLITE_IOERR_FSTAT";       break;
1365       case SQLITE_IOERR_UNLOCK:       zName = "SQLITE_IOERR_UNLOCK";      break;
1366       case SQLITE_IOERR_RDLOCK:       zName = "SQLITE_IOERR_RDLOCK";      break;
1367       case SQLITE_IOERR_DELETE:       zName = "SQLITE_IOERR_DELETE";      break;
1368       case SQLITE_IOERR_NOMEM:        zName = "SQLITE_IOERR_NOMEM";       break;
1369       case SQLITE_IOERR_ACCESS:       zName = "SQLITE_IOERR_ACCESS";      break;
1370       case SQLITE_IOERR_CHECKRESERVEDLOCK:
1371                                 zName = "SQLITE_IOERR_CHECKRESERVEDLOCK"; break;
1372       case SQLITE_IOERR_LOCK:         zName = "SQLITE_IOERR_LOCK";        break;
1373       case SQLITE_IOERR_CLOSE:        zName = "SQLITE_IOERR_CLOSE";       break;
1374       case SQLITE_IOERR_DIR_CLOSE:    zName = "SQLITE_IOERR_DIR_CLOSE";   break;
1375       case SQLITE_IOERR_SHMOPEN:      zName = "SQLITE_IOERR_SHMOPEN";     break;
1376       case SQLITE_IOERR_SHMSIZE:      zName = "SQLITE_IOERR_SHMSIZE";     break;
1377       case SQLITE_IOERR_SHMLOCK:      zName = "SQLITE_IOERR_SHMLOCK";     break;
1378       case SQLITE_IOERR_SHMMAP:       zName = "SQLITE_IOERR_SHMMAP";      break;
1379       case SQLITE_IOERR_SEEK:         zName = "SQLITE_IOERR_SEEK";        break;
1380       case SQLITE_IOERR_DELETE_NOENT: zName = "SQLITE_IOERR_DELETE_NOENT";break;
1381       case SQLITE_IOERR_MMAP:         zName = "SQLITE_IOERR_MMAP";        break;
1382       case SQLITE_IOERR_GETTEMPPATH:  zName = "SQLITE_IOERR_GETTEMPPATH"; break;
1383       case SQLITE_IOERR_CONVPATH:     zName = "SQLITE_IOERR_CONVPATH";    break;
1384       case SQLITE_CORRUPT:            zName = "SQLITE_CORRUPT";           break;
1385       case SQLITE_CORRUPT_VTAB:       zName = "SQLITE_CORRUPT_VTAB";      break;
1386       case SQLITE_NOTFOUND:           zName = "SQLITE_NOTFOUND";          break;
1387       case SQLITE_FULL:               zName = "SQLITE_FULL";              break;
1388       case SQLITE_CANTOPEN:           zName = "SQLITE_CANTOPEN";          break;
1389       case SQLITE_CANTOPEN_NOTEMPDIR: zName = "SQLITE_CANTOPEN_NOTEMPDIR";break;
1390       case SQLITE_CANTOPEN_ISDIR:     zName = "SQLITE_CANTOPEN_ISDIR";    break;
1391       case SQLITE_CANTOPEN_FULLPATH:  zName = "SQLITE_CANTOPEN_FULLPATH"; break;
1392       case SQLITE_CANTOPEN_CONVPATH:  zName = "SQLITE_CANTOPEN_CONVPATH"; break;
1393       case SQLITE_PROTOCOL:           zName = "SQLITE_PROTOCOL";          break;
1394       case SQLITE_EMPTY:              zName = "SQLITE_EMPTY";             break;
1395       case SQLITE_SCHEMA:             zName = "SQLITE_SCHEMA";            break;
1396       case SQLITE_TOOBIG:             zName = "SQLITE_TOOBIG";            break;
1397       case SQLITE_CONSTRAINT:         zName = "SQLITE_CONSTRAINT";        break;
1398       case SQLITE_CONSTRAINT_UNIQUE:  zName = "SQLITE_CONSTRAINT_UNIQUE"; break;
1399       case SQLITE_CONSTRAINT_TRIGGER: zName = "SQLITE_CONSTRAINT_TRIGGER";break;
1400       case SQLITE_CONSTRAINT_FOREIGNKEY:
1401                                 zName = "SQLITE_CONSTRAINT_FOREIGNKEY";   break;
1402       case SQLITE_CONSTRAINT_CHECK:   zName = "SQLITE_CONSTRAINT_CHECK";  break;
1403       case SQLITE_CONSTRAINT_PRIMARYKEY:
1404                                 zName = "SQLITE_CONSTRAINT_PRIMARYKEY";   break;
1405       case SQLITE_CONSTRAINT_NOTNULL: zName = "SQLITE_CONSTRAINT_NOTNULL";break;
1406       case SQLITE_CONSTRAINT_COMMITHOOK:
1407                                 zName = "SQLITE_CONSTRAINT_COMMITHOOK";   break;
1408       case SQLITE_CONSTRAINT_VTAB:    zName = "SQLITE_CONSTRAINT_VTAB";   break;
1409       case SQLITE_CONSTRAINT_FUNCTION:
1410                                 zName = "SQLITE_CONSTRAINT_FUNCTION";     break;
1411       case SQLITE_CONSTRAINT_ROWID:   zName = "SQLITE_CONSTRAINT_ROWID";  break;
1412       case SQLITE_MISMATCH:           zName = "SQLITE_MISMATCH";          break;
1413       case SQLITE_MISUSE:             zName = "SQLITE_MISUSE";            break;
1414       case SQLITE_NOLFS:              zName = "SQLITE_NOLFS";             break;
1415       case SQLITE_AUTH:               zName = "SQLITE_AUTH";              break;
1416       case SQLITE_FORMAT:             zName = "SQLITE_FORMAT";            break;
1417       case SQLITE_RANGE:              zName = "SQLITE_RANGE";             break;
1418       case SQLITE_NOTADB:             zName = "SQLITE_NOTADB";            break;
1419       case SQLITE_ROW:                zName = "SQLITE_ROW";               break;
1420       case SQLITE_NOTICE:             zName = "SQLITE_NOTICE";            break;
1421       case SQLITE_NOTICE_RECOVER_WAL: zName = "SQLITE_NOTICE_RECOVER_WAL";break;
1422       case SQLITE_NOTICE_RECOVER_ROLLBACK:
1423                                 zName = "SQLITE_NOTICE_RECOVER_ROLLBACK"; break;
1424       case SQLITE_WARNING:            zName = "SQLITE_WARNING";           break;
1425       case SQLITE_WARNING_AUTOINDEX:  zName = "SQLITE_WARNING_AUTOINDEX"; break;
1426       case SQLITE_DONE:               zName = "SQLITE_DONE";              break;
1427     }
1428   }
1429   if( zName==0 ){
1430     static char zBuf[50];
1431     sqlite3_snprintf(sizeof(zBuf), zBuf, "SQLITE_UNKNOWN(%d)", origRc);
1432     zName = zBuf;
1433   }
1434   return zName;
1435 }
1436 #endif
1437 
1438 /*
1439 ** Return a static string that describes the kind of error specified in the
1440 ** argument.
1441 */
1442 const char *sqlite3ErrStr(int rc){
1443   static const char* const aMsg[] = {
1444     /* SQLITE_OK          */ "not an error",
1445     /* SQLITE_ERROR       */ "SQL logic error",
1446     /* SQLITE_INTERNAL    */ 0,
1447     /* SQLITE_PERM        */ "access permission denied",
1448     /* SQLITE_ABORT       */ "query aborted",
1449     /* SQLITE_BUSY        */ "database is locked",
1450     /* SQLITE_LOCKED      */ "database table is locked",
1451     /* SQLITE_NOMEM       */ "out of memory",
1452     /* SQLITE_READONLY    */ "attempt to write a readonly database",
1453     /* SQLITE_INTERRUPT   */ "interrupted",
1454     /* SQLITE_IOERR       */ "disk I/O error",
1455     /* SQLITE_CORRUPT     */ "database disk image is malformed",
1456     /* SQLITE_NOTFOUND    */ "unknown operation",
1457     /* SQLITE_FULL        */ "database or disk is full",
1458     /* SQLITE_CANTOPEN    */ "unable to open database file",
1459     /* SQLITE_PROTOCOL    */ "locking protocol",
1460     /* SQLITE_EMPTY       */ 0,
1461     /* SQLITE_SCHEMA      */ "database schema has changed",
1462     /* SQLITE_TOOBIG      */ "string or blob too big",
1463     /* SQLITE_CONSTRAINT  */ "constraint failed",
1464     /* SQLITE_MISMATCH    */ "datatype mismatch",
1465     /* SQLITE_MISUSE      */ "bad parameter or other API misuse",
1466 #ifdef SQLITE_DISABLE_LFS
1467     /* SQLITE_NOLFS       */ "large file support is disabled",
1468 #else
1469     /* SQLITE_NOLFS       */ 0,
1470 #endif
1471     /* SQLITE_AUTH        */ "authorization denied",
1472     /* SQLITE_FORMAT      */ 0,
1473     /* SQLITE_RANGE       */ "column index out of range",
1474     /* SQLITE_NOTADB      */ "file is not a database",
1475     /* SQLITE_NOTICE      */ "notification message",
1476     /* SQLITE_WARNING     */ "warning message",
1477   };
1478   const char *zErr = "unknown error";
1479   switch( rc ){
1480     case SQLITE_ABORT_ROLLBACK: {
1481       zErr = "abort due to ROLLBACK";
1482       break;
1483     }
1484     case SQLITE_ROW: {
1485       zErr = "another row available";
1486       break;
1487     }
1488     case SQLITE_DONE: {
1489       zErr = "no more rows available";
1490       break;
1491     }
1492     default: {
1493       rc &= 0xff;
1494       if( ALWAYS(rc>=0) && rc<ArraySize(aMsg) && aMsg[rc]!=0 ){
1495         zErr = aMsg[rc];
1496       }
1497       break;
1498     }
1499   }
1500   return zErr;
1501 }
1502 
1503 /*
1504 ** This routine implements a busy callback that sleeps and tries
1505 ** again until a timeout value is reached.  The timeout value is
1506 ** an integer number of milliseconds passed in as the first
1507 ** argument.
1508 **
1509 ** Return non-zero to retry the lock.  Return zero to stop trying
1510 ** and cause SQLite to return SQLITE_BUSY.
1511 */
1512 static int sqliteDefaultBusyCallback(
1513   void *ptr,               /* Database connection */
1514   int count,               /* Number of times table has been busy */
1515   sqlite3_file *pFile      /* The file on which the lock occurred */
1516 ){
1517 #if SQLITE_OS_WIN || HAVE_USLEEP
1518   /* This case is for systems that have support for sleeping for fractions of
1519   ** a second.  Examples:  All windows systems, unix systems with usleep() */
1520   static const u8 delays[] =
1521      { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
1522   static const u8 totals[] =
1523      { 0, 1, 3,  8, 18, 33, 53, 78, 103, 128, 178, 228 };
1524 # define NDELAY ArraySize(delays)
1525   sqlite3 *db = (sqlite3 *)ptr;
1526   int tmout = db->busyTimeout;
1527   int delay, prior;
1528 
1529 #ifdef SQLITE_ENABLE_SETLK_TIMEOUT
1530   if( sqlite3OsFileControl(pFile,SQLITE_FCNTL_LOCK_TIMEOUT,&tmout)==SQLITE_OK ){
1531     if( count ){
1532       tmout = 0;
1533       sqlite3OsFileControl(pFile, SQLITE_FCNTL_LOCK_TIMEOUT, &tmout);
1534       return 0;
1535     }else{
1536       return 1;
1537     }
1538   }
1539 #else
1540   UNUSED_PARAMETER(pFile);
1541 #endif
1542   assert( count>=0 );
1543   if( count < NDELAY ){
1544     delay = delays[count];
1545     prior = totals[count];
1546   }else{
1547     delay = delays[NDELAY-1];
1548     prior = totals[NDELAY-1] + delay*(count-(NDELAY-1));
1549   }
1550   if( prior + delay > tmout ){
1551     delay = tmout - prior;
1552     if( delay<=0 ) return 0;
1553   }
1554   sqlite3OsSleep(db->pVfs, delay*1000);
1555   return 1;
1556 #else
1557   /* This case for unix systems that lack usleep() support.  Sleeping
1558   ** must be done in increments of whole seconds */
1559   sqlite3 *db = (sqlite3 *)ptr;
1560   int tmout = ((sqlite3 *)ptr)->busyTimeout;
1561   UNUSED_PARAMETER(pFile);
1562   if( (count+1)*1000 > tmout ){
1563     return 0;
1564   }
1565   sqlite3OsSleep(db->pVfs, 1000000);
1566   return 1;
1567 #endif
1568 }
1569 
1570 /*
1571 ** Invoke the given busy handler.
1572 **
1573 ** This routine is called when an operation failed to acquire a
1574 ** lock on VFS file pFile.
1575 **
1576 ** If this routine returns non-zero, the lock is retried.  If it
1577 ** returns 0, the operation aborts with an SQLITE_BUSY error.
1578 */
1579 int sqlite3InvokeBusyHandler(BusyHandler *p, sqlite3_file *pFile){
1580   int rc;
1581   if( p->xBusyHandler==0 || p->nBusy<0 ) return 0;
1582   if( p->bExtraFileArg ){
1583     /* Add an extra parameter with the pFile pointer to the end of the
1584     ** callback argument list */
1585     int (*xTra)(void*,int,sqlite3_file*);
1586     xTra = (int(*)(void*,int,sqlite3_file*))p->xBusyHandler;
1587     rc = xTra(p->pBusyArg, p->nBusy, pFile);
1588   }else{
1589     /* Legacy style busy handler callback */
1590     rc = p->xBusyHandler(p->pBusyArg, p->nBusy);
1591   }
1592   if( rc==0 ){
1593     p->nBusy = -1;
1594   }else{
1595     p->nBusy++;
1596   }
1597   return rc;
1598 }
1599 
1600 /*
1601 ** This routine sets the busy callback for an Sqlite database to the
1602 ** given callback function with the given argument.
1603 */
1604 int sqlite3_busy_handler(
1605   sqlite3 *db,
1606   int (*xBusy)(void*,int),
1607   void *pArg
1608 ){
1609 #ifdef SQLITE_ENABLE_API_ARMOR
1610   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
1611 #endif
1612   sqlite3_mutex_enter(db->mutex);
1613   db->busyHandler.xBusyHandler = xBusy;
1614   db->busyHandler.pBusyArg = pArg;
1615   db->busyHandler.nBusy = 0;
1616   db->busyHandler.bExtraFileArg = 0;
1617   db->busyTimeout = 0;
1618   sqlite3_mutex_leave(db->mutex);
1619   return SQLITE_OK;
1620 }
1621 
1622 #ifndef SQLITE_OMIT_PROGRESS_CALLBACK
1623 /*
1624 ** This routine sets the progress callback for an Sqlite database to the
1625 ** given callback function with the given argument. The progress callback will
1626 ** be invoked every nOps opcodes.
1627 */
1628 void sqlite3_progress_handler(
1629   sqlite3 *db,
1630   int nOps,
1631   int (*xProgress)(void*),
1632   void *pArg
1633 ){
1634 #ifdef SQLITE_ENABLE_API_ARMOR
1635   if( !sqlite3SafetyCheckOk(db) ){
1636     (void)SQLITE_MISUSE_BKPT;
1637     return;
1638   }
1639 #endif
1640   sqlite3_mutex_enter(db->mutex);
1641   if( nOps>0 ){
1642     db->xProgress = xProgress;
1643     db->nProgressOps = (unsigned)nOps;
1644     db->pProgressArg = pArg;
1645   }else{
1646     db->xProgress = 0;
1647     db->nProgressOps = 0;
1648     db->pProgressArg = 0;
1649   }
1650   sqlite3_mutex_leave(db->mutex);
1651 }
1652 #endif
1653 
1654 
1655 /*
1656 ** This routine installs a default busy handler that waits for the
1657 ** specified number of milliseconds before returning 0.
1658 */
1659 int sqlite3_busy_timeout(sqlite3 *db, int ms){
1660 #ifdef SQLITE_ENABLE_API_ARMOR
1661   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
1662 #endif
1663   if( ms>0 ){
1664     sqlite3_busy_handler(db, (int(*)(void*,int))sqliteDefaultBusyCallback,
1665                              (void*)db);
1666     db->busyTimeout = ms;
1667     db->busyHandler.bExtraFileArg = 1;
1668   }else{
1669     sqlite3_busy_handler(db, 0, 0);
1670   }
1671   return SQLITE_OK;
1672 }
1673 
1674 /*
1675 ** Cause any pending operation to stop at its earliest opportunity.
1676 */
1677 void sqlite3_interrupt(sqlite3 *db){
1678 #ifdef SQLITE_ENABLE_API_ARMOR
1679   if( !sqlite3SafetyCheckOk(db) && (db==0 || db->magic!=SQLITE_MAGIC_ZOMBIE) ){
1680     (void)SQLITE_MISUSE_BKPT;
1681     return;
1682   }
1683 #endif
1684   db->u1.isInterrupted = 1;
1685 }
1686 
1687 
1688 /*
1689 ** This function is exactly the same as sqlite3_create_function(), except
1690 ** that it is designed to be called by internal code. The difference is
1691 ** that if a malloc() fails in sqlite3_create_function(), an error code
1692 ** is returned and the mallocFailed flag cleared.
1693 */
1694 int sqlite3CreateFunc(
1695   sqlite3 *db,
1696   const char *zFunctionName,
1697   int nArg,
1698   int enc,
1699   void *pUserData,
1700   void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
1701   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1702   void (*xFinal)(sqlite3_context*),
1703   void (*xValue)(sqlite3_context*),
1704   void (*xInverse)(sqlite3_context*,int,sqlite3_value **),
1705   FuncDestructor *pDestructor
1706 ){
1707   FuncDef *p;
1708   int nName;
1709   int extraFlags;
1710 
1711   assert( sqlite3_mutex_held(db->mutex) );
1712   assert( xValue==0 || xSFunc==0 );
1713   if( zFunctionName==0                /* Must have a valid name */
1714    || (xSFunc!=0 && xFinal!=0)        /* Not both xSFunc and xFinal */
1715    || ((xFinal==0)!=(xStep==0))       /* Both or neither of xFinal and xStep */
1716    || ((xValue==0)!=(xInverse==0))    /* Both or neither of xValue, xInverse */
1717    || (nArg<-1 || nArg>SQLITE_MAX_FUNCTION_ARG)
1718    || (255<(nName = sqlite3Strlen30( zFunctionName)))
1719   ){
1720     return SQLITE_MISUSE_BKPT;
1721   }
1722 
1723   assert( SQLITE_FUNC_CONSTANT==SQLITE_DETERMINISTIC );
1724   assert( SQLITE_FUNC_DIRECT==SQLITE_DIRECTONLY );
1725   extraFlags = enc &  (SQLITE_DETERMINISTIC|SQLITE_DIRECTONLY|SQLITE_SUBTYPE);
1726   enc &= (SQLITE_FUNC_ENCMASK|SQLITE_ANY);
1727 
1728 #ifndef SQLITE_OMIT_UTF16
1729   /* If SQLITE_UTF16 is specified as the encoding type, transform this
1730   ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
1731   ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
1732   **
1733   ** If SQLITE_ANY is specified, add three versions of the function
1734   ** to the hash table.
1735   */
1736   if( enc==SQLITE_UTF16 ){
1737     enc = SQLITE_UTF16NATIVE;
1738   }else if( enc==SQLITE_ANY ){
1739     int rc;
1740     rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF8|extraFlags,
1741          pUserData, xSFunc, xStep, xFinal, xValue, xInverse, pDestructor);
1742     if( rc==SQLITE_OK ){
1743       rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF16LE|extraFlags,
1744           pUserData, xSFunc, xStep, xFinal, xValue, xInverse, pDestructor);
1745     }
1746     if( rc!=SQLITE_OK ){
1747       return rc;
1748     }
1749     enc = SQLITE_UTF16BE;
1750   }
1751 #else
1752   enc = SQLITE_UTF8;
1753 #endif
1754 
1755   /* Check if an existing function is being overridden or deleted. If so,
1756   ** and there are active VMs, then return SQLITE_BUSY. If a function
1757   ** is being overridden/deleted but there are no active VMs, allow the
1758   ** operation to continue but invalidate all precompiled statements.
1759   */
1760   p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 0);
1761   if( p && (p->funcFlags & SQLITE_FUNC_ENCMASK)==(u32)enc && p->nArg==nArg ){
1762     if( db->nVdbeActive ){
1763       sqlite3ErrorWithMsg(db, SQLITE_BUSY,
1764         "unable to delete/modify user-function due to active statements");
1765       assert( !db->mallocFailed );
1766       return SQLITE_BUSY;
1767     }else{
1768       sqlite3ExpirePreparedStatements(db, 0);
1769     }
1770   }
1771 
1772   p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 1);
1773   assert(p || db->mallocFailed);
1774   if( !p ){
1775     return SQLITE_NOMEM_BKPT;
1776   }
1777 
1778   /* If an older version of the function with a configured destructor is
1779   ** being replaced invoke the destructor function here. */
1780   functionDestroy(db, p);
1781 
1782   if( pDestructor ){
1783     pDestructor->nRef++;
1784   }
1785   p->u.pDestructor = pDestructor;
1786   p->funcFlags = (p->funcFlags & SQLITE_FUNC_ENCMASK) | extraFlags;
1787   testcase( p->funcFlags & SQLITE_DETERMINISTIC );
1788   testcase( p->funcFlags & SQLITE_DIRECTONLY );
1789   p->xSFunc = xSFunc ? xSFunc : xStep;
1790   p->xFinalize = xFinal;
1791   p->xValue = xValue;
1792   p->xInverse = xInverse;
1793   p->pUserData = pUserData;
1794   p->nArg = (u16)nArg;
1795   return SQLITE_OK;
1796 }
1797 
1798 /*
1799 ** Worker function used by utf-8 APIs that create new functions:
1800 **
1801 **    sqlite3_create_function()
1802 **    sqlite3_create_function_v2()
1803 **    sqlite3_create_window_function()
1804 */
1805 static int createFunctionApi(
1806   sqlite3 *db,
1807   const char *zFunc,
1808   int nArg,
1809   int enc,
1810   void *p,
1811   void (*xSFunc)(sqlite3_context*,int,sqlite3_value**),
1812   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
1813   void (*xFinal)(sqlite3_context*),
1814   void (*xValue)(sqlite3_context*),
1815   void (*xInverse)(sqlite3_context*,int,sqlite3_value**),
1816   void(*xDestroy)(void*)
1817 ){
1818   int rc = SQLITE_ERROR;
1819   FuncDestructor *pArg = 0;
1820 
1821 #ifdef SQLITE_ENABLE_API_ARMOR
1822   if( !sqlite3SafetyCheckOk(db) ){
1823     return SQLITE_MISUSE_BKPT;
1824   }
1825 #endif
1826   sqlite3_mutex_enter(db->mutex);
1827   if( xDestroy ){
1828     pArg = (FuncDestructor *)sqlite3Malloc(sizeof(FuncDestructor));
1829     if( !pArg ){
1830       sqlite3OomFault(db);
1831       xDestroy(p);
1832       goto out;
1833     }
1834     pArg->nRef = 0;
1835     pArg->xDestroy = xDestroy;
1836     pArg->pUserData = p;
1837   }
1838   rc = sqlite3CreateFunc(db, zFunc, nArg, enc, p,
1839       xSFunc, xStep, xFinal, xValue, xInverse, pArg
1840   );
1841   if( pArg && pArg->nRef==0 ){
1842     assert( rc!=SQLITE_OK );
1843     xDestroy(p);
1844     sqlite3_free(pArg);
1845   }
1846 
1847  out:
1848   rc = sqlite3ApiExit(db, rc);
1849   sqlite3_mutex_leave(db->mutex);
1850   return rc;
1851 }
1852 
1853 /*
1854 ** Create new user functions.
1855 */
1856 int sqlite3_create_function(
1857   sqlite3 *db,
1858   const char *zFunc,
1859   int nArg,
1860   int enc,
1861   void *p,
1862   void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
1863   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1864   void (*xFinal)(sqlite3_context*)
1865 ){
1866   return createFunctionApi(db, zFunc, nArg, enc, p, xSFunc, xStep,
1867                                     xFinal, 0, 0, 0);
1868 }
1869 int sqlite3_create_function_v2(
1870   sqlite3 *db,
1871   const char *zFunc,
1872   int nArg,
1873   int enc,
1874   void *p,
1875   void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
1876   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1877   void (*xFinal)(sqlite3_context*),
1878   void (*xDestroy)(void *)
1879 ){
1880   return createFunctionApi(db, zFunc, nArg, enc, p, xSFunc, xStep,
1881                                     xFinal, 0, 0, xDestroy);
1882 }
1883 int sqlite3_create_window_function(
1884   sqlite3 *db,
1885   const char *zFunc,
1886   int nArg,
1887   int enc,
1888   void *p,
1889   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1890   void (*xFinal)(sqlite3_context*),
1891   void (*xValue)(sqlite3_context*),
1892   void (*xInverse)(sqlite3_context*,int,sqlite3_value **),
1893   void (*xDestroy)(void *)
1894 ){
1895   return createFunctionApi(db, zFunc, nArg, enc, p, 0, xStep,
1896                                     xFinal, xValue, xInverse, xDestroy);
1897 }
1898 
1899 #ifndef SQLITE_OMIT_UTF16
1900 int sqlite3_create_function16(
1901   sqlite3 *db,
1902   const void *zFunctionName,
1903   int nArg,
1904   int eTextRep,
1905   void *p,
1906   void (*xSFunc)(sqlite3_context*,int,sqlite3_value**),
1907   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
1908   void (*xFinal)(sqlite3_context*)
1909 ){
1910   int rc;
1911   char *zFunc8;
1912 
1913 #ifdef SQLITE_ENABLE_API_ARMOR
1914   if( !sqlite3SafetyCheckOk(db) || zFunctionName==0 ) return SQLITE_MISUSE_BKPT;
1915 #endif
1916   sqlite3_mutex_enter(db->mutex);
1917   assert( !db->mallocFailed );
1918   zFunc8 = sqlite3Utf16to8(db, zFunctionName, -1, SQLITE_UTF16NATIVE);
1919   rc = sqlite3CreateFunc(db, zFunc8, nArg, eTextRep, p, xSFunc,xStep,xFinal,0,0,0);
1920   sqlite3DbFree(db, zFunc8);
1921   rc = sqlite3ApiExit(db, rc);
1922   sqlite3_mutex_leave(db->mutex);
1923   return rc;
1924 }
1925 #endif
1926 
1927 
1928 /*
1929 ** The following is the implementation of an SQL function that always
1930 ** fails with an error message stating that the function is used in the
1931 ** wrong context.  The sqlite3_overload_function() API might construct
1932 ** SQL function that use this routine so that the functions will exist
1933 ** for name resolution but are actually overloaded by the xFindFunction
1934 ** method of virtual tables.
1935 */
1936 static void sqlite3InvalidFunction(
1937   sqlite3_context *context,  /* The function calling context */
1938   int NotUsed,               /* Number of arguments to the function */
1939   sqlite3_value **NotUsed2   /* Value of each argument */
1940 ){
1941   const char *zName = (const char*)sqlite3_user_data(context);
1942   char *zErr;
1943   UNUSED_PARAMETER2(NotUsed, NotUsed2);
1944   zErr = sqlite3_mprintf(
1945       "unable to use function %s in the requested context", zName);
1946   sqlite3_result_error(context, zErr, -1);
1947   sqlite3_free(zErr);
1948 }
1949 
1950 /*
1951 ** Declare that a function has been overloaded by a virtual table.
1952 **
1953 ** If the function already exists as a regular global function, then
1954 ** this routine is a no-op.  If the function does not exist, then create
1955 ** a new one that always throws a run-time error.
1956 **
1957 ** When virtual tables intend to provide an overloaded function, they
1958 ** should call this routine to make sure the global function exists.
1959 ** A global function must exist in order for name resolution to work
1960 ** properly.
1961 */
1962 int sqlite3_overload_function(
1963   sqlite3 *db,
1964   const char *zName,
1965   int nArg
1966 ){
1967   int rc;
1968   char *zCopy;
1969 
1970 #ifdef SQLITE_ENABLE_API_ARMOR
1971   if( !sqlite3SafetyCheckOk(db) || zName==0 || nArg<-2 ){
1972     return SQLITE_MISUSE_BKPT;
1973   }
1974 #endif
1975   sqlite3_mutex_enter(db->mutex);
1976   rc = sqlite3FindFunction(db, zName, nArg, SQLITE_UTF8, 0)!=0;
1977   sqlite3_mutex_leave(db->mutex);
1978   if( rc ) return SQLITE_OK;
1979   zCopy = sqlite3_mprintf(zName);
1980   if( zCopy==0 ) return SQLITE_NOMEM;
1981   return sqlite3_create_function_v2(db, zName, nArg, SQLITE_UTF8,
1982                            zCopy, sqlite3InvalidFunction, 0, 0, sqlite3_free);
1983 }
1984 
1985 #ifndef SQLITE_OMIT_TRACE
1986 /*
1987 ** Register a trace function.  The pArg from the previously registered trace
1988 ** is returned.
1989 **
1990 ** A NULL trace function means that no tracing is executes.  A non-NULL
1991 ** trace is a pointer to a function that is invoked at the start of each
1992 ** SQL statement.
1993 */
1994 #ifndef SQLITE_OMIT_DEPRECATED
1995 void *sqlite3_trace(sqlite3 *db, void(*xTrace)(void*,const char*), void *pArg){
1996   void *pOld;
1997 
1998 #ifdef SQLITE_ENABLE_API_ARMOR
1999   if( !sqlite3SafetyCheckOk(db) ){
2000     (void)SQLITE_MISUSE_BKPT;
2001     return 0;
2002   }
2003 #endif
2004   sqlite3_mutex_enter(db->mutex);
2005   pOld = db->pTraceArg;
2006   db->mTrace = xTrace ? SQLITE_TRACE_LEGACY : 0;
2007   db->xTrace = (int(*)(u32,void*,void*,void*))xTrace;
2008   db->pTraceArg = pArg;
2009   sqlite3_mutex_leave(db->mutex);
2010   return pOld;
2011 }
2012 #endif /* SQLITE_OMIT_DEPRECATED */
2013 
2014 /* Register a trace callback using the version-2 interface.
2015 */
2016 int sqlite3_trace_v2(
2017   sqlite3 *db,                               /* Trace this connection */
2018   unsigned mTrace,                           /* Mask of events to be traced */
2019   int(*xTrace)(unsigned,void*,void*,void*),  /* Callback to invoke */
2020   void *pArg                                 /* Context */
2021 ){
2022 #ifdef SQLITE_ENABLE_API_ARMOR
2023   if( !sqlite3SafetyCheckOk(db) ){
2024     return SQLITE_MISUSE_BKPT;
2025   }
2026 #endif
2027   sqlite3_mutex_enter(db->mutex);
2028   if( mTrace==0 ) xTrace = 0;
2029   if( xTrace==0 ) mTrace = 0;
2030   db->mTrace = mTrace;
2031   db->xTrace = xTrace;
2032   db->pTraceArg = pArg;
2033   sqlite3_mutex_leave(db->mutex);
2034   return SQLITE_OK;
2035 }
2036 
2037 #ifndef SQLITE_OMIT_DEPRECATED
2038 /*
2039 ** Register a profile function.  The pArg from the previously registered
2040 ** profile function is returned.
2041 **
2042 ** A NULL profile function means that no profiling is executes.  A non-NULL
2043 ** profile is a pointer to a function that is invoked at the conclusion of
2044 ** each SQL statement that is run.
2045 */
2046 void *sqlite3_profile(
2047   sqlite3 *db,
2048   void (*xProfile)(void*,const char*,sqlite_uint64),
2049   void *pArg
2050 ){
2051   void *pOld;
2052 
2053 #ifdef SQLITE_ENABLE_API_ARMOR
2054   if( !sqlite3SafetyCheckOk(db) ){
2055     (void)SQLITE_MISUSE_BKPT;
2056     return 0;
2057   }
2058 #endif
2059   sqlite3_mutex_enter(db->mutex);
2060   pOld = db->pProfileArg;
2061   db->xProfile = xProfile;
2062   db->pProfileArg = pArg;
2063   db->mTrace &= SQLITE_TRACE_NONLEGACY_MASK;
2064   if( db->xProfile ) db->mTrace |= SQLITE_TRACE_XPROFILE;
2065   sqlite3_mutex_leave(db->mutex);
2066   return pOld;
2067 }
2068 #endif /* SQLITE_OMIT_DEPRECATED */
2069 #endif /* SQLITE_OMIT_TRACE */
2070 
2071 /*
2072 ** Register a function to be invoked when a transaction commits.
2073 ** If the invoked function returns non-zero, then the commit becomes a
2074 ** rollback.
2075 */
2076 void *sqlite3_commit_hook(
2077   sqlite3 *db,              /* Attach the hook to this database */
2078   int (*xCallback)(void*),  /* Function to invoke on each commit */
2079   void *pArg                /* Argument to the function */
2080 ){
2081   void *pOld;
2082 
2083 #ifdef SQLITE_ENABLE_API_ARMOR
2084   if( !sqlite3SafetyCheckOk(db) ){
2085     (void)SQLITE_MISUSE_BKPT;
2086     return 0;
2087   }
2088 #endif
2089   sqlite3_mutex_enter(db->mutex);
2090   pOld = db->pCommitArg;
2091   db->xCommitCallback = xCallback;
2092   db->pCommitArg = pArg;
2093   sqlite3_mutex_leave(db->mutex);
2094   return pOld;
2095 }
2096 
2097 /*
2098 ** Register a callback to be invoked each time a row is updated,
2099 ** inserted or deleted using this database connection.
2100 */
2101 void *sqlite3_update_hook(
2102   sqlite3 *db,              /* Attach the hook to this database */
2103   void (*xCallback)(void*,int,char const *,char const *,sqlite_int64),
2104   void *pArg                /* Argument to the function */
2105 ){
2106   void *pRet;
2107 
2108 #ifdef SQLITE_ENABLE_API_ARMOR
2109   if( !sqlite3SafetyCheckOk(db) ){
2110     (void)SQLITE_MISUSE_BKPT;
2111     return 0;
2112   }
2113 #endif
2114   sqlite3_mutex_enter(db->mutex);
2115   pRet = db->pUpdateArg;
2116   db->xUpdateCallback = xCallback;
2117   db->pUpdateArg = pArg;
2118   sqlite3_mutex_leave(db->mutex);
2119   return pRet;
2120 }
2121 
2122 /*
2123 ** Register a callback to be invoked each time a transaction is rolled
2124 ** back by this database connection.
2125 */
2126 void *sqlite3_rollback_hook(
2127   sqlite3 *db,              /* Attach the hook to this database */
2128   void (*xCallback)(void*), /* Callback function */
2129   void *pArg                /* Argument to the function */
2130 ){
2131   void *pRet;
2132 
2133 #ifdef SQLITE_ENABLE_API_ARMOR
2134   if( !sqlite3SafetyCheckOk(db) ){
2135     (void)SQLITE_MISUSE_BKPT;
2136     return 0;
2137   }
2138 #endif
2139   sqlite3_mutex_enter(db->mutex);
2140   pRet = db->pRollbackArg;
2141   db->xRollbackCallback = xCallback;
2142   db->pRollbackArg = pArg;
2143   sqlite3_mutex_leave(db->mutex);
2144   return pRet;
2145 }
2146 
2147 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
2148 /*
2149 ** Register a callback to be invoked each time a row is updated,
2150 ** inserted or deleted using this database connection.
2151 */
2152 void *sqlite3_preupdate_hook(
2153   sqlite3 *db,              /* Attach the hook to this database */
2154   void(*xCallback)(         /* Callback function */
2155     void*,sqlite3*,int,char const*,char const*,sqlite3_int64,sqlite3_int64),
2156   void *pArg                /* First callback argument */
2157 ){
2158   void *pRet;
2159   sqlite3_mutex_enter(db->mutex);
2160   pRet = db->pPreUpdateArg;
2161   db->xPreUpdateCallback = xCallback;
2162   db->pPreUpdateArg = pArg;
2163   sqlite3_mutex_leave(db->mutex);
2164   return pRet;
2165 }
2166 #endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
2167 
2168 #ifndef SQLITE_OMIT_WAL
2169 /*
2170 ** The sqlite3_wal_hook() callback registered by sqlite3_wal_autocheckpoint().
2171 ** Invoke sqlite3_wal_checkpoint if the number of frames in the log file
2172 ** is greater than sqlite3.pWalArg cast to an integer (the value configured by
2173 ** wal_autocheckpoint()).
2174 */
2175 int sqlite3WalDefaultHook(
2176   void *pClientData,     /* Argument */
2177   sqlite3 *db,           /* Connection */
2178   const char *zDb,       /* Database */
2179   int nFrame             /* Size of WAL */
2180 ){
2181   if( nFrame>=SQLITE_PTR_TO_INT(pClientData) ){
2182     sqlite3BeginBenignMalloc();
2183     sqlite3_wal_checkpoint(db, zDb);
2184     sqlite3EndBenignMalloc();
2185   }
2186   return SQLITE_OK;
2187 }
2188 #endif /* SQLITE_OMIT_WAL */
2189 
2190 /*
2191 ** Configure an sqlite3_wal_hook() callback to automatically checkpoint
2192 ** a database after committing a transaction if there are nFrame or
2193 ** more frames in the log file. Passing zero or a negative value as the
2194 ** nFrame parameter disables automatic checkpoints entirely.
2195 **
2196 ** The callback registered by this function replaces any existing callback
2197 ** registered using sqlite3_wal_hook(). Likewise, registering a callback
2198 ** using sqlite3_wal_hook() disables the automatic checkpoint mechanism
2199 ** configured by this function.
2200 */
2201 int sqlite3_wal_autocheckpoint(sqlite3 *db, int nFrame){
2202 #ifdef SQLITE_OMIT_WAL
2203   UNUSED_PARAMETER(db);
2204   UNUSED_PARAMETER(nFrame);
2205 #else
2206 #ifdef SQLITE_ENABLE_API_ARMOR
2207   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
2208 #endif
2209   if( nFrame>0 ){
2210     sqlite3_wal_hook(db, sqlite3WalDefaultHook, SQLITE_INT_TO_PTR(nFrame));
2211   }else{
2212     sqlite3_wal_hook(db, 0, 0);
2213   }
2214 #endif
2215   return SQLITE_OK;
2216 }
2217 
2218 /*
2219 ** Register a callback to be invoked each time a transaction is written
2220 ** into the write-ahead-log by this database connection.
2221 */
2222 void *sqlite3_wal_hook(
2223   sqlite3 *db,                    /* Attach the hook to this db handle */
2224   int(*xCallback)(void *, sqlite3*, const char*, int),
2225   void *pArg                      /* First argument passed to xCallback() */
2226 ){
2227 #ifndef SQLITE_OMIT_WAL
2228   void *pRet;
2229 #ifdef SQLITE_ENABLE_API_ARMOR
2230   if( !sqlite3SafetyCheckOk(db) ){
2231     (void)SQLITE_MISUSE_BKPT;
2232     return 0;
2233   }
2234 #endif
2235   sqlite3_mutex_enter(db->mutex);
2236   pRet = db->pWalArg;
2237   db->xWalCallback = xCallback;
2238   db->pWalArg = pArg;
2239   sqlite3_mutex_leave(db->mutex);
2240   return pRet;
2241 #else
2242   return 0;
2243 #endif
2244 }
2245 
2246 /*
2247 ** Checkpoint database zDb.
2248 */
2249 int sqlite3_wal_checkpoint_v2(
2250   sqlite3 *db,                    /* Database handle */
2251   const char *zDb,                /* Name of attached database (or NULL) */
2252   int eMode,                      /* SQLITE_CHECKPOINT_* value */
2253   int *pnLog,                     /* OUT: Size of WAL log in frames */
2254   int *pnCkpt                     /* OUT: Total number of frames checkpointed */
2255 ){
2256 #ifdef SQLITE_OMIT_WAL
2257   return SQLITE_OK;
2258 #else
2259   int rc;                         /* Return code */
2260   int iDb = SQLITE_MAX_ATTACHED;  /* sqlite3.aDb[] index of db to checkpoint */
2261 
2262 #ifdef SQLITE_ENABLE_API_ARMOR
2263   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
2264 #endif
2265 
2266   /* Initialize the output variables to -1 in case an error occurs. */
2267   if( pnLog ) *pnLog = -1;
2268   if( pnCkpt ) *pnCkpt = -1;
2269 
2270   assert( SQLITE_CHECKPOINT_PASSIVE==0 );
2271   assert( SQLITE_CHECKPOINT_FULL==1 );
2272   assert( SQLITE_CHECKPOINT_RESTART==2 );
2273   assert( SQLITE_CHECKPOINT_TRUNCATE==3 );
2274   if( eMode<SQLITE_CHECKPOINT_PASSIVE || eMode>SQLITE_CHECKPOINT_TRUNCATE ){
2275     /* EVIDENCE-OF: R-03996-12088 The M parameter must be a valid checkpoint
2276     ** mode: */
2277     return SQLITE_MISUSE;
2278   }
2279 
2280   sqlite3_mutex_enter(db->mutex);
2281   if( zDb && zDb[0] ){
2282     iDb = sqlite3FindDbName(db, zDb);
2283   }
2284   if( iDb<0 ){
2285     rc = SQLITE_ERROR;
2286     sqlite3ErrorWithMsg(db, SQLITE_ERROR, "unknown database: %s", zDb);
2287   }else{
2288     db->busyHandler.nBusy = 0;
2289     rc = sqlite3Checkpoint(db, iDb, eMode, pnLog, pnCkpt);
2290     sqlite3Error(db, rc);
2291   }
2292   rc = sqlite3ApiExit(db, rc);
2293 
2294   /* If there are no active statements, clear the interrupt flag at this
2295   ** point.  */
2296   if( db->nVdbeActive==0 ){
2297     db->u1.isInterrupted = 0;
2298   }
2299 
2300   sqlite3_mutex_leave(db->mutex);
2301   return rc;
2302 #endif
2303 }
2304 
2305 
2306 /*
2307 ** Checkpoint database zDb. If zDb is NULL, or if the buffer zDb points
2308 ** to contains a zero-length string, all attached databases are
2309 ** checkpointed.
2310 */
2311 int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb){
2312   /* EVIDENCE-OF: R-41613-20553 The sqlite3_wal_checkpoint(D,X) is equivalent to
2313   ** sqlite3_wal_checkpoint_v2(D,X,SQLITE_CHECKPOINT_PASSIVE,0,0). */
2314   return sqlite3_wal_checkpoint_v2(db,zDb,SQLITE_CHECKPOINT_PASSIVE,0,0);
2315 }
2316 
2317 #ifndef SQLITE_OMIT_WAL
2318 /*
2319 ** Run a checkpoint on database iDb. This is a no-op if database iDb is
2320 ** not currently open in WAL mode.
2321 **
2322 ** If a transaction is open on the database being checkpointed, this
2323 ** function returns SQLITE_LOCKED and a checkpoint is not attempted. If
2324 ** an error occurs while running the checkpoint, an SQLite error code is
2325 ** returned (i.e. SQLITE_IOERR). Otherwise, SQLITE_OK.
2326 **
2327 ** The mutex on database handle db should be held by the caller. The mutex
2328 ** associated with the specific b-tree being checkpointed is taken by
2329 ** this function while the checkpoint is running.
2330 **
2331 ** If iDb is passed SQLITE_MAX_ATTACHED, then all attached databases are
2332 ** checkpointed. If an error is encountered it is returned immediately -
2333 ** no attempt is made to checkpoint any remaining databases.
2334 **
2335 ** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL, RESTART
2336 ** or TRUNCATE.
2337 */
2338 int sqlite3Checkpoint(sqlite3 *db, int iDb, int eMode, int *pnLog, int *pnCkpt){
2339   int rc = SQLITE_OK;             /* Return code */
2340   int i;                          /* Used to iterate through attached dbs */
2341   int bBusy = 0;                  /* True if SQLITE_BUSY has been encountered */
2342 
2343   assert( sqlite3_mutex_held(db->mutex) );
2344   assert( !pnLog || *pnLog==-1 );
2345   assert( !pnCkpt || *pnCkpt==-1 );
2346 
2347   for(i=0; i<db->nDb && rc==SQLITE_OK; i++){
2348     if( i==iDb || iDb==SQLITE_MAX_ATTACHED ){
2349       rc = sqlite3BtreeCheckpoint(db->aDb[i].pBt, eMode, pnLog, pnCkpt);
2350       pnLog = 0;
2351       pnCkpt = 0;
2352       if( rc==SQLITE_BUSY ){
2353         bBusy = 1;
2354         rc = SQLITE_OK;
2355       }
2356     }
2357   }
2358 
2359   return (rc==SQLITE_OK && bBusy) ? SQLITE_BUSY : rc;
2360 }
2361 #endif /* SQLITE_OMIT_WAL */
2362 
2363 /*
2364 ** This function returns true if main-memory should be used instead of
2365 ** a temporary file for transient pager files and statement journals.
2366 ** The value returned depends on the value of db->temp_store (runtime
2367 ** parameter) and the compile time value of SQLITE_TEMP_STORE. The
2368 ** following table describes the relationship between these two values
2369 ** and this functions return value.
2370 **
2371 **   SQLITE_TEMP_STORE     db->temp_store     Location of temporary database
2372 **   -----------------     --------------     ------------------------------
2373 **   0                     any                file      (return 0)
2374 **   1                     1                  file      (return 0)
2375 **   1                     2                  memory    (return 1)
2376 **   1                     0                  file      (return 0)
2377 **   2                     1                  file      (return 0)
2378 **   2                     2                  memory    (return 1)
2379 **   2                     0                  memory    (return 1)
2380 **   3                     any                memory    (return 1)
2381 */
2382 int sqlite3TempInMemory(const sqlite3 *db){
2383 #if SQLITE_TEMP_STORE==1
2384   return ( db->temp_store==2 );
2385 #endif
2386 #if SQLITE_TEMP_STORE==2
2387   return ( db->temp_store!=1 );
2388 #endif
2389 #if SQLITE_TEMP_STORE==3
2390   UNUSED_PARAMETER(db);
2391   return 1;
2392 #endif
2393 #if SQLITE_TEMP_STORE<1 || SQLITE_TEMP_STORE>3
2394   UNUSED_PARAMETER(db);
2395   return 0;
2396 #endif
2397 }
2398 
2399 /*
2400 ** Return UTF-8 encoded English language explanation of the most recent
2401 ** error.
2402 */
2403 const char *sqlite3_errmsg(sqlite3 *db){
2404   const char *z;
2405   if( !db ){
2406     return sqlite3ErrStr(SQLITE_NOMEM_BKPT);
2407   }
2408   if( !sqlite3SafetyCheckSickOrOk(db) ){
2409     return sqlite3ErrStr(SQLITE_MISUSE_BKPT);
2410   }
2411   sqlite3_mutex_enter(db->mutex);
2412   if( db->mallocFailed ){
2413     z = sqlite3ErrStr(SQLITE_NOMEM_BKPT);
2414   }else{
2415     testcase( db->pErr==0 );
2416     z = db->errCode ? (char*)sqlite3_value_text(db->pErr) : 0;
2417     assert( !db->mallocFailed );
2418     if( z==0 ){
2419       z = sqlite3ErrStr(db->errCode);
2420     }
2421   }
2422   sqlite3_mutex_leave(db->mutex);
2423   return z;
2424 }
2425 
2426 #ifndef SQLITE_OMIT_UTF16
2427 /*
2428 ** Return UTF-16 encoded English language explanation of the most recent
2429 ** error.
2430 */
2431 const void *sqlite3_errmsg16(sqlite3 *db){
2432   static const u16 outOfMem[] = {
2433     'o', 'u', 't', ' ', 'o', 'f', ' ', 'm', 'e', 'm', 'o', 'r', 'y', 0
2434   };
2435   static const u16 misuse[] = {
2436     'b', 'a', 'd', ' ', 'p', 'a', 'r', 'a', 'm', 'e', 't', 'e', 'r', ' ',
2437     'o', 'r', ' ', 'o', 't', 'h', 'e', 'r', ' ', 'A', 'P', 'I', ' ',
2438     'm', 'i', 's', 'u', 's', 'e', 0
2439   };
2440 
2441   const void *z;
2442   if( !db ){
2443     return (void *)outOfMem;
2444   }
2445   if( !sqlite3SafetyCheckSickOrOk(db) ){
2446     return (void *)misuse;
2447   }
2448   sqlite3_mutex_enter(db->mutex);
2449   if( db->mallocFailed ){
2450     z = (void *)outOfMem;
2451   }else{
2452     z = sqlite3_value_text16(db->pErr);
2453     if( z==0 ){
2454       sqlite3ErrorWithMsg(db, db->errCode, sqlite3ErrStr(db->errCode));
2455       z = sqlite3_value_text16(db->pErr);
2456     }
2457     /* A malloc() may have failed within the call to sqlite3_value_text16()
2458     ** above. If this is the case, then the db->mallocFailed flag needs to
2459     ** be cleared before returning. Do this directly, instead of via
2460     ** sqlite3ApiExit(), to avoid setting the database handle error message.
2461     */
2462     sqlite3OomClear(db);
2463   }
2464   sqlite3_mutex_leave(db->mutex);
2465   return z;
2466 }
2467 #endif /* SQLITE_OMIT_UTF16 */
2468 
2469 /*
2470 ** Return the most recent error code generated by an SQLite routine. If NULL is
2471 ** passed to this function, we assume a malloc() failed during sqlite3_open().
2472 */
2473 int sqlite3_errcode(sqlite3 *db){
2474   if( db && !sqlite3SafetyCheckSickOrOk(db) ){
2475     return SQLITE_MISUSE_BKPT;
2476   }
2477   if( !db || db->mallocFailed ){
2478     return SQLITE_NOMEM_BKPT;
2479   }
2480   return db->errCode & db->errMask;
2481 }
2482 int sqlite3_extended_errcode(sqlite3 *db){
2483   if( db && !sqlite3SafetyCheckSickOrOk(db) ){
2484     return SQLITE_MISUSE_BKPT;
2485   }
2486   if( !db || db->mallocFailed ){
2487     return SQLITE_NOMEM_BKPT;
2488   }
2489   return db->errCode;
2490 }
2491 int sqlite3_system_errno(sqlite3 *db){
2492   return db ? db->iSysErrno : 0;
2493 }
2494 
2495 /*
2496 ** Return a string that describes the kind of error specified in the
2497 ** argument.  For now, this simply calls the internal sqlite3ErrStr()
2498 ** function.
2499 */
2500 const char *sqlite3_errstr(int rc){
2501   return sqlite3ErrStr(rc);
2502 }
2503 
2504 /*
2505 ** Create a new collating function for database "db".  The name is zName
2506 ** and the encoding is enc.
2507 */
2508 static int createCollation(
2509   sqlite3* db,
2510   const char *zName,
2511   u8 enc,
2512   void* pCtx,
2513   int(*xCompare)(void*,int,const void*,int,const void*),
2514   void(*xDel)(void*)
2515 ){
2516   CollSeq *pColl;
2517   int enc2;
2518 
2519   assert( sqlite3_mutex_held(db->mutex) );
2520 
2521   /* If SQLITE_UTF16 is specified as the encoding type, transform this
2522   ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
2523   ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
2524   */
2525   enc2 = enc;
2526   testcase( enc2==SQLITE_UTF16 );
2527   testcase( enc2==SQLITE_UTF16_ALIGNED );
2528   if( enc2==SQLITE_UTF16 || enc2==SQLITE_UTF16_ALIGNED ){
2529     enc2 = SQLITE_UTF16NATIVE;
2530   }
2531   if( enc2<SQLITE_UTF8 || enc2>SQLITE_UTF16BE ){
2532     return SQLITE_MISUSE_BKPT;
2533   }
2534 
2535   /* Check if this call is removing or replacing an existing collation
2536   ** sequence. If so, and there are active VMs, return busy. If there
2537   ** are no active VMs, invalidate any pre-compiled statements.
2538   */
2539   pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 0);
2540   if( pColl && pColl->xCmp ){
2541     if( db->nVdbeActive ){
2542       sqlite3ErrorWithMsg(db, SQLITE_BUSY,
2543         "unable to delete/modify collation sequence due to active statements");
2544       return SQLITE_BUSY;
2545     }
2546     sqlite3ExpirePreparedStatements(db, 0);
2547 
2548     /* If collation sequence pColl was created directly by a call to
2549     ** sqlite3_create_collation, and not generated by synthCollSeq(),
2550     ** then any copies made by synthCollSeq() need to be invalidated.
2551     ** Also, collation destructor - CollSeq.xDel() - function may need
2552     ** to be called.
2553     */
2554     if( (pColl->enc & ~SQLITE_UTF16_ALIGNED)==enc2 ){
2555       CollSeq *aColl = sqlite3HashFind(&db->aCollSeq, zName);
2556       int j;
2557       for(j=0; j<3; j++){
2558         CollSeq *p = &aColl[j];
2559         if( p->enc==pColl->enc ){
2560           if( p->xDel ){
2561             p->xDel(p->pUser);
2562           }
2563           p->xCmp = 0;
2564         }
2565       }
2566     }
2567   }
2568 
2569   pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 1);
2570   if( pColl==0 ) return SQLITE_NOMEM_BKPT;
2571   pColl->xCmp = xCompare;
2572   pColl->pUser = pCtx;
2573   pColl->xDel = xDel;
2574   pColl->enc = (u8)(enc2 | (enc & SQLITE_UTF16_ALIGNED));
2575   sqlite3Error(db, SQLITE_OK);
2576   return SQLITE_OK;
2577 }
2578 
2579 
2580 /*
2581 ** This array defines hard upper bounds on limit values.  The
2582 ** initializer must be kept in sync with the SQLITE_LIMIT_*
2583 ** #defines in sqlite3.h.
2584 */
2585 static const int aHardLimit[] = {
2586   SQLITE_MAX_LENGTH,
2587   SQLITE_MAX_SQL_LENGTH,
2588   SQLITE_MAX_COLUMN,
2589   SQLITE_MAX_EXPR_DEPTH,
2590   SQLITE_MAX_COMPOUND_SELECT,
2591   SQLITE_MAX_VDBE_OP,
2592   SQLITE_MAX_FUNCTION_ARG,
2593   SQLITE_MAX_ATTACHED,
2594   SQLITE_MAX_LIKE_PATTERN_LENGTH,
2595   SQLITE_MAX_VARIABLE_NUMBER,      /* IMP: R-38091-32352 */
2596   SQLITE_MAX_TRIGGER_DEPTH,
2597   SQLITE_MAX_WORKER_THREADS,
2598 };
2599 
2600 /*
2601 ** Make sure the hard limits are set to reasonable values
2602 */
2603 #if SQLITE_MAX_LENGTH<100
2604 # error SQLITE_MAX_LENGTH must be at least 100
2605 #endif
2606 #if SQLITE_MAX_SQL_LENGTH<100
2607 # error SQLITE_MAX_SQL_LENGTH must be at least 100
2608 #endif
2609 #if SQLITE_MAX_SQL_LENGTH>SQLITE_MAX_LENGTH
2610 # error SQLITE_MAX_SQL_LENGTH must not be greater than SQLITE_MAX_LENGTH
2611 #endif
2612 #if SQLITE_MAX_COMPOUND_SELECT<2
2613 # error SQLITE_MAX_COMPOUND_SELECT must be at least 2
2614 #endif
2615 #if SQLITE_MAX_VDBE_OP<40
2616 # error SQLITE_MAX_VDBE_OP must be at least 40
2617 #endif
2618 #if SQLITE_MAX_FUNCTION_ARG<0 || SQLITE_MAX_FUNCTION_ARG>127
2619 # error SQLITE_MAX_FUNCTION_ARG must be between 0 and 127
2620 #endif
2621 #if SQLITE_MAX_ATTACHED<0 || SQLITE_MAX_ATTACHED>125
2622 # error SQLITE_MAX_ATTACHED must be between 0 and 125
2623 #endif
2624 #if SQLITE_MAX_LIKE_PATTERN_LENGTH<1
2625 # error SQLITE_MAX_LIKE_PATTERN_LENGTH must be at least 1
2626 #endif
2627 #if SQLITE_MAX_COLUMN>32767
2628 # error SQLITE_MAX_COLUMN must not exceed 32767
2629 #endif
2630 #if SQLITE_MAX_TRIGGER_DEPTH<1
2631 # error SQLITE_MAX_TRIGGER_DEPTH must be at least 1
2632 #endif
2633 #if SQLITE_MAX_WORKER_THREADS<0 || SQLITE_MAX_WORKER_THREADS>50
2634 # error SQLITE_MAX_WORKER_THREADS must be between 0 and 50
2635 #endif
2636 
2637 
2638 /*
2639 ** Change the value of a limit.  Report the old value.
2640 ** If an invalid limit index is supplied, report -1.
2641 ** Make no changes but still report the old value if the
2642 ** new limit is negative.
2643 **
2644 ** A new lower limit does not shrink existing constructs.
2645 ** It merely prevents new constructs that exceed the limit
2646 ** from forming.
2647 */
2648 int sqlite3_limit(sqlite3 *db, int limitId, int newLimit){
2649   int oldLimit;
2650 
2651 #ifdef SQLITE_ENABLE_API_ARMOR
2652   if( !sqlite3SafetyCheckOk(db) ){
2653     (void)SQLITE_MISUSE_BKPT;
2654     return -1;
2655   }
2656 #endif
2657 
2658   /* EVIDENCE-OF: R-30189-54097 For each limit category SQLITE_LIMIT_NAME
2659   ** there is a hard upper bound set at compile-time by a C preprocessor
2660   ** macro called SQLITE_MAX_NAME. (The "_LIMIT_" in the name is changed to
2661   ** "_MAX_".)
2662   */
2663   assert( aHardLimit[SQLITE_LIMIT_LENGTH]==SQLITE_MAX_LENGTH );
2664   assert( aHardLimit[SQLITE_LIMIT_SQL_LENGTH]==SQLITE_MAX_SQL_LENGTH );
2665   assert( aHardLimit[SQLITE_LIMIT_COLUMN]==SQLITE_MAX_COLUMN );
2666   assert( aHardLimit[SQLITE_LIMIT_EXPR_DEPTH]==SQLITE_MAX_EXPR_DEPTH );
2667   assert( aHardLimit[SQLITE_LIMIT_COMPOUND_SELECT]==SQLITE_MAX_COMPOUND_SELECT);
2668   assert( aHardLimit[SQLITE_LIMIT_VDBE_OP]==SQLITE_MAX_VDBE_OP );
2669   assert( aHardLimit[SQLITE_LIMIT_FUNCTION_ARG]==SQLITE_MAX_FUNCTION_ARG );
2670   assert( aHardLimit[SQLITE_LIMIT_ATTACHED]==SQLITE_MAX_ATTACHED );
2671   assert( aHardLimit[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]==
2672                                                SQLITE_MAX_LIKE_PATTERN_LENGTH );
2673   assert( aHardLimit[SQLITE_LIMIT_VARIABLE_NUMBER]==SQLITE_MAX_VARIABLE_NUMBER);
2674   assert( aHardLimit[SQLITE_LIMIT_TRIGGER_DEPTH]==SQLITE_MAX_TRIGGER_DEPTH );
2675   assert( aHardLimit[SQLITE_LIMIT_WORKER_THREADS]==SQLITE_MAX_WORKER_THREADS );
2676   assert( SQLITE_LIMIT_WORKER_THREADS==(SQLITE_N_LIMIT-1) );
2677 
2678 
2679   if( limitId<0 || limitId>=SQLITE_N_LIMIT ){
2680     return -1;
2681   }
2682   oldLimit = db->aLimit[limitId];
2683   if( newLimit>=0 ){                   /* IMP: R-52476-28732 */
2684     if( newLimit>aHardLimit[limitId] ){
2685       newLimit = aHardLimit[limitId];  /* IMP: R-51463-25634 */
2686     }
2687     db->aLimit[limitId] = newLimit;
2688   }
2689   return oldLimit;                     /* IMP: R-53341-35419 */
2690 }
2691 
2692 /*
2693 ** This function is used to parse both URIs and non-URI filenames passed by the
2694 ** user to API functions sqlite3_open() or sqlite3_open_v2(), and for database
2695 ** URIs specified as part of ATTACH statements.
2696 **
2697 ** The first argument to this function is the name of the VFS to use (or
2698 ** a NULL to signify the default VFS) if the URI does not contain a "vfs=xxx"
2699 ** query parameter. The second argument contains the URI (or non-URI filename)
2700 ** itself. When this function is called the *pFlags variable should contain
2701 ** the default flags to open the database handle with. The value stored in
2702 ** *pFlags may be updated before returning if the URI filename contains
2703 ** "cache=xxx" or "mode=xxx" query parameters.
2704 **
2705 ** If successful, SQLITE_OK is returned. In this case *ppVfs is set to point to
2706 ** the VFS that should be used to open the database file. *pzFile is set to
2707 ** point to a buffer containing the name of the file to open. It is the
2708 ** responsibility of the caller to eventually call sqlite3_free() to release
2709 ** this buffer.
2710 **
2711 ** If an error occurs, then an SQLite error code is returned and *pzErrMsg
2712 ** may be set to point to a buffer containing an English language error
2713 ** message. It is the responsibility of the caller to eventually release
2714 ** this buffer by calling sqlite3_free().
2715 */
2716 int sqlite3ParseUri(
2717   const char *zDefaultVfs,        /* VFS to use if no "vfs=xxx" query option */
2718   const char *zUri,               /* Nul-terminated URI to parse */
2719   unsigned int *pFlags,           /* IN/OUT: SQLITE_OPEN_XXX flags */
2720   sqlite3_vfs **ppVfs,            /* OUT: VFS to use */
2721   char **pzFile,                  /* OUT: Filename component of URI */
2722   char **pzErrMsg                 /* OUT: Error message (if rc!=SQLITE_OK) */
2723 ){
2724   int rc = SQLITE_OK;
2725   unsigned int flags = *pFlags;
2726   const char *zVfs = zDefaultVfs;
2727   char *zFile;
2728   char c;
2729   int nUri = sqlite3Strlen30(zUri);
2730 
2731   assert( *pzErrMsg==0 );
2732 
2733   if( ((flags & SQLITE_OPEN_URI)             /* IMP: R-48725-32206 */
2734             || sqlite3GlobalConfig.bOpenUri) /* IMP: R-51689-46548 */
2735    && nUri>=5 && memcmp(zUri, "file:", 5)==0 /* IMP: R-57884-37496 */
2736   ){
2737     char *zOpt;
2738     int eState;                   /* Parser state when parsing URI */
2739     int iIn;                      /* Input character index */
2740     int iOut = 0;                 /* Output character index */
2741     u64 nByte = nUri+2;           /* Bytes of space to allocate */
2742 
2743     /* Make sure the SQLITE_OPEN_URI flag is set to indicate to the VFS xOpen
2744     ** method that there may be extra parameters following the file-name.  */
2745     flags |= SQLITE_OPEN_URI;
2746 
2747     for(iIn=0; iIn<nUri; iIn++) nByte += (zUri[iIn]=='&');
2748     zFile = sqlite3_malloc64(nByte);
2749     if( !zFile ) return SQLITE_NOMEM_BKPT;
2750 
2751     iIn = 5;
2752 #ifdef SQLITE_ALLOW_URI_AUTHORITY
2753     if( strncmp(zUri+5, "///", 3)==0 ){
2754       iIn = 7;
2755       /* The following condition causes URIs with five leading / characters
2756       ** like file://///host/path to be converted into UNCs like //host/path.
2757       ** The correct URI for that UNC has only two or four leading / characters
2758       ** file://host/path or file:////host/path.  But 5 leading slashes is a
2759       ** common error, we are told, so we handle it as a special case. */
2760       if( strncmp(zUri+7, "///", 3)==0 ){ iIn++; }
2761     }else if( strncmp(zUri+5, "//localhost/", 12)==0 ){
2762       iIn = 16;
2763     }
2764 #else
2765     /* Discard the scheme and authority segments of the URI. */
2766     if( zUri[5]=='/' && zUri[6]=='/' ){
2767       iIn = 7;
2768       while( zUri[iIn] && zUri[iIn]!='/' ) iIn++;
2769       if( iIn!=7 && (iIn!=16 || memcmp("localhost", &zUri[7], 9)) ){
2770         *pzErrMsg = sqlite3_mprintf("invalid uri authority: %.*s",
2771             iIn-7, &zUri[7]);
2772         rc = SQLITE_ERROR;
2773         goto parse_uri_out;
2774       }
2775     }
2776 #endif
2777 
2778     /* Copy the filename and any query parameters into the zFile buffer.
2779     ** Decode %HH escape codes along the way.
2780     **
2781     ** Within this loop, variable eState may be set to 0, 1 or 2, depending
2782     ** on the parsing context. As follows:
2783     **
2784     **   0: Parsing file-name.
2785     **   1: Parsing name section of a name=value query parameter.
2786     **   2: Parsing value section of a name=value query parameter.
2787     */
2788     eState = 0;
2789     while( (c = zUri[iIn])!=0 && c!='#' ){
2790       iIn++;
2791       if( c=='%'
2792        && sqlite3Isxdigit(zUri[iIn])
2793        && sqlite3Isxdigit(zUri[iIn+1])
2794       ){
2795         int octet = (sqlite3HexToInt(zUri[iIn++]) << 4);
2796         octet += sqlite3HexToInt(zUri[iIn++]);
2797 
2798         assert( octet>=0 && octet<256 );
2799         if( octet==0 ){
2800 #ifndef SQLITE_ENABLE_URI_00_ERROR
2801           /* This branch is taken when "%00" appears within the URI. In this
2802           ** case we ignore all text in the remainder of the path, name or
2803           ** value currently being parsed. So ignore the current character
2804           ** and skip to the next "?", "=" or "&", as appropriate. */
2805           while( (c = zUri[iIn])!=0 && c!='#'
2806               && (eState!=0 || c!='?')
2807               && (eState!=1 || (c!='=' && c!='&'))
2808               && (eState!=2 || c!='&')
2809           ){
2810             iIn++;
2811           }
2812           continue;
2813 #else
2814           /* If ENABLE_URI_00_ERROR is defined, "%00" in a URI is an error. */
2815           *pzErrMsg = sqlite3_mprintf("unexpected %%00 in uri");
2816           rc = SQLITE_ERROR;
2817           goto parse_uri_out;
2818 #endif
2819         }
2820         c = octet;
2821       }else if( eState==1 && (c=='&' || c=='=') ){
2822         if( zFile[iOut-1]==0 ){
2823           /* An empty option name. Ignore this option altogether. */
2824           while( zUri[iIn] && zUri[iIn]!='#' && zUri[iIn-1]!='&' ) iIn++;
2825           continue;
2826         }
2827         if( c=='&' ){
2828           zFile[iOut++] = '\0';
2829         }else{
2830           eState = 2;
2831         }
2832         c = 0;
2833       }else if( (eState==0 && c=='?') || (eState==2 && c=='&') ){
2834         c = 0;
2835         eState = 1;
2836       }
2837       zFile[iOut++] = c;
2838     }
2839     if( eState==1 ) zFile[iOut++] = '\0';
2840     zFile[iOut++] = '\0';
2841     zFile[iOut++] = '\0';
2842 
2843     /* Check if there were any options specified that should be interpreted
2844     ** here. Options that are interpreted here include "vfs" and those that
2845     ** correspond to flags that may be passed to the sqlite3_open_v2()
2846     ** method. */
2847     zOpt = &zFile[sqlite3Strlen30(zFile)+1];
2848     while( zOpt[0] ){
2849       int nOpt = sqlite3Strlen30(zOpt);
2850       char *zVal = &zOpt[nOpt+1];
2851       int nVal = sqlite3Strlen30(zVal);
2852 
2853       if( nOpt==3 && memcmp("vfs", zOpt, 3)==0 ){
2854         zVfs = zVal;
2855       }else{
2856         struct OpenMode {
2857           const char *z;
2858           int mode;
2859         } *aMode = 0;
2860         char *zModeType = 0;
2861         int mask = 0;
2862         int limit = 0;
2863 
2864         if( nOpt==5 && memcmp("cache", zOpt, 5)==0 ){
2865           static struct OpenMode aCacheMode[] = {
2866             { "shared",  SQLITE_OPEN_SHAREDCACHE },
2867             { "private", SQLITE_OPEN_PRIVATECACHE },
2868             { 0, 0 }
2869           };
2870 
2871           mask = SQLITE_OPEN_SHAREDCACHE|SQLITE_OPEN_PRIVATECACHE;
2872           aMode = aCacheMode;
2873           limit = mask;
2874           zModeType = "cache";
2875         }
2876         if( nOpt==4 && memcmp("mode", zOpt, 4)==0 ){
2877           static struct OpenMode aOpenMode[] = {
2878             { "ro",  SQLITE_OPEN_READONLY },
2879             { "rw",  SQLITE_OPEN_READWRITE },
2880             { "rwc", SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE },
2881             { "memory", SQLITE_OPEN_MEMORY },
2882             { 0, 0 }
2883           };
2884 
2885           mask = SQLITE_OPEN_READONLY | SQLITE_OPEN_READWRITE
2886                    | SQLITE_OPEN_CREATE | SQLITE_OPEN_MEMORY;
2887           aMode = aOpenMode;
2888           limit = mask & flags;
2889           zModeType = "access";
2890         }
2891 
2892         if( aMode ){
2893           int i;
2894           int mode = 0;
2895           for(i=0; aMode[i].z; i++){
2896             const char *z = aMode[i].z;
2897             if( nVal==sqlite3Strlen30(z) && 0==memcmp(zVal, z, nVal) ){
2898               mode = aMode[i].mode;
2899               break;
2900             }
2901           }
2902           if( mode==0 ){
2903             *pzErrMsg = sqlite3_mprintf("no such %s mode: %s", zModeType, zVal);
2904             rc = SQLITE_ERROR;
2905             goto parse_uri_out;
2906           }
2907           if( (mode & ~SQLITE_OPEN_MEMORY)>limit ){
2908             *pzErrMsg = sqlite3_mprintf("%s mode not allowed: %s",
2909                                         zModeType, zVal);
2910             rc = SQLITE_PERM;
2911             goto parse_uri_out;
2912           }
2913           flags = (flags & ~mask) | mode;
2914         }
2915       }
2916 
2917       zOpt = &zVal[nVal+1];
2918     }
2919 
2920   }else{
2921     zFile = sqlite3_malloc64(nUri+2);
2922     if( !zFile ) return SQLITE_NOMEM_BKPT;
2923     if( nUri ){
2924       memcpy(zFile, zUri, nUri);
2925     }
2926     zFile[nUri] = '\0';
2927     zFile[nUri+1] = '\0';
2928     flags &= ~SQLITE_OPEN_URI;
2929   }
2930 
2931   *ppVfs = sqlite3_vfs_find(zVfs);
2932   if( *ppVfs==0 ){
2933     *pzErrMsg = sqlite3_mprintf("no such vfs: %s", zVfs);
2934     rc = SQLITE_ERROR;
2935   }
2936  parse_uri_out:
2937   if( rc!=SQLITE_OK ){
2938     sqlite3_free(zFile);
2939     zFile = 0;
2940   }
2941   *pFlags = flags;
2942   *pzFile = zFile;
2943   return rc;
2944 }
2945 
2946 #if defined(SQLITE_HAS_CODEC)
2947 /*
2948 ** Process URI filename query parameters relevant to the SQLite Encryption
2949 ** Extension.  Return true if any of the relevant query parameters are
2950 ** seen and return false if not.
2951 */
2952 int sqlite3CodecQueryParameters(
2953   sqlite3 *db,           /* Database connection */
2954   const char *zDb,       /* Which schema is being created/attached */
2955   const char *zUri       /* URI filename */
2956 ){
2957   const char *zKey;
2958   if( (zKey = sqlite3_uri_parameter(zUri, "hexkey"))!=0 && zKey[0] ){
2959     u8 iByte;
2960     int i;
2961     char zDecoded[40];
2962     for(i=0, iByte=0; i<sizeof(zDecoded)*2 && sqlite3Isxdigit(zKey[i]); i++){
2963       iByte = (iByte<<4) + sqlite3HexToInt(zKey[i]);
2964       if( (i&1)!=0 ) zDecoded[i/2] = iByte;
2965     }
2966     sqlite3_key_v2(db, zDb, zDecoded, i/2);
2967     return 1;
2968   }else if( (zKey = sqlite3_uri_parameter(zUri, "key"))!=0 ){
2969     sqlite3_key_v2(db, zDb, zKey, sqlite3Strlen30(zKey));
2970     return 1;
2971   }else if( (zKey = sqlite3_uri_parameter(zUri, "textkey"))!=0 ){
2972     sqlite3_key_v2(db, zDb, zKey, -1);
2973     return 1;
2974   }else{
2975     return 0;
2976   }
2977 }
2978 #endif
2979 
2980 
2981 /*
2982 ** This routine does the work of opening a database on behalf of
2983 ** sqlite3_open() and sqlite3_open16(). The database filename "zFilename"
2984 ** is UTF-8 encoded.
2985 */
2986 static int openDatabase(
2987   const char *zFilename, /* Database filename UTF-8 encoded */
2988   sqlite3 **ppDb,        /* OUT: Returned database handle */
2989   unsigned int flags,    /* Operational flags */
2990   const char *zVfs       /* Name of the VFS to use */
2991 ){
2992   sqlite3 *db;                    /* Store allocated handle here */
2993   int rc;                         /* Return code */
2994   int isThreadsafe;               /* True for threadsafe connections */
2995   char *zOpen = 0;                /* Filename argument to pass to BtreeOpen() */
2996   char *zErrMsg = 0;              /* Error message from sqlite3ParseUri() */
2997 
2998 #ifdef SQLITE_ENABLE_API_ARMOR
2999   if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
3000 #endif
3001   *ppDb = 0;
3002 #ifndef SQLITE_OMIT_AUTOINIT
3003   rc = sqlite3_initialize();
3004   if( rc ) return rc;
3005 #endif
3006 
3007   if( sqlite3GlobalConfig.bCoreMutex==0 ){
3008     isThreadsafe = 0;
3009   }else if( flags & SQLITE_OPEN_NOMUTEX ){
3010     isThreadsafe = 0;
3011   }else if( flags & SQLITE_OPEN_FULLMUTEX ){
3012     isThreadsafe = 1;
3013   }else{
3014     isThreadsafe = sqlite3GlobalConfig.bFullMutex;
3015   }
3016 
3017   if( flags & SQLITE_OPEN_PRIVATECACHE ){
3018     flags &= ~SQLITE_OPEN_SHAREDCACHE;
3019   }else if( sqlite3GlobalConfig.sharedCacheEnabled ){
3020     flags |= SQLITE_OPEN_SHAREDCACHE;
3021   }
3022 
3023   /* Remove harmful bits from the flags parameter
3024   **
3025   ** The SQLITE_OPEN_NOMUTEX and SQLITE_OPEN_FULLMUTEX flags were
3026   ** dealt with in the previous code block.  Besides these, the only
3027   ** valid input flags for sqlite3_open_v2() are SQLITE_OPEN_READONLY,
3028   ** SQLITE_OPEN_READWRITE, SQLITE_OPEN_CREATE, SQLITE_OPEN_SHAREDCACHE,
3029   ** SQLITE_OPEN_PRIVATECACHE, and some reserved bits.  Silently mask
3030   ** off all other flags.
3031   */
3032   flags &=  ~( SQLITE_OPEN_DELETEONCLOSE |
3033                SQLITE_OPEN_EXCLUSIVE |
3034                SQLITE_OPEN_MAIN_DB |
3035                SQLITE_OPEN_TEMP_DB |
3036                SQLITE_OPEN_TRANSIENT_DB |
3037                SQLITE_OPEN_MAIN_JOURNAL |
3038                SQLITE_OPEN_TEMP_JOURNAL |
3039                SQLITE_OPEN_SUBJOURNAL |
3040                SQLITE_OPEN_MASTER_JOURNAL |
3041                SQLITE_OPEN_NOMUTEX |
3042                SQLITE_OPEN_FULLMUTEX |
3043                SQLITE_OPEN_WAL
3044              );
3045 
3046   /* Allocate the sqlite data structure */
3047   db = sqlite3MallocZero( sizeof(sqlite3) );
3048   if( db==0 ) goto opendb_out;
3049   if( isThreadsafe
3050 #ifdef SQLITE_ENABLE_MULTITHREADED_CHECKS
3051    || sqlite3GlobalConfig.bCoreMutex
3052 #endif
3053   ){
3054     db->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
3055     if( db->mutex==0 ){
3056       sqlite3_free(db);
3057       db = 0;
3058       goto opendb_out;
3059     }
3060     if( isThreadsafe==0 ){
3061       sqlite3MutexWarnOnContention(db->mutex);
3062     }
3063   }
3064   sqlite3_mutex_enter(db->mutex);
3065   db->errMask = 0xff;
3066   db->nDb = 2;
3067   db->magic = SQLITE_MAGIC_BUSY;
3068   db->aDb = db->aDbStatic;
3069   db->lookaside.bDisable = 1;
3070   db->lookaside.sz = 0;
3071 
3072   assert( sizeof(db->aLimit)==sizeof(aHardLimit) );
3073   memcpy(db->aLimit, aHardLimit, sizeof(db->aLimit));
3074   db->aLimit[SQLITE_LIMIT_WORKER_THREADS] = SQLITE_DEFAULT_WORKER_THREADS;
3075   db->autoCommit = 1;
3076   db->nextAutovac = -1;
3077   db->szMmap = sqlite3GlobalConfig.szMmap;
3078   db->nextPagesize = 0;
3079   db->nMaxSorterMmap = 0x7FFFFFFF;
3080   db->flags |= SQLITE_ShortColNames
3081                  | SQLITE_EnableTrigger
3082                  | SQLITE_EnableView
3083                  | SQLITE_CacheSpill
3084 
3085 /* The SQLITE_DQS compile-time option determines the default settings
3086 ** for SQLITE_DBCONFIG_DQS_DDL and SQLITE_DBCONFIG_DQS_DML.
3087 **
3088 **    SQLITE_DQS     SQLITE_DBCONFIG_DQS_DDL    SQLITE_DBCONFIG_DQS_DML
3089 **    ----------     -----------------------    -----------------------
3090 **     undefined               on                          on
3091 **         3                   on                          on
3092 **         2                   on                         off
3093 **         1                  off                          on
3094 **         0                  off                         off
3095 **
3096 ** Legacy behavior is 3 (double-quoted string literals are allowed anywhere)
3097 ** and so that is the default.  But developers are encouranged to use
3098 ** -DSQLITE_DQS=0 (best) or -DSQLITE_DQS=1 (second choice) if possible.
3099 */
3100 #if !defined(SQLITE_DQS)
3101 # define SQLITE_DQS 3
3102 #endif
3103 #if (SQLITE_DQS&1)==1
3104                  | SQLITE_DqsDML
3105 #endif
3106 #if (SQLITE_DQS&2)==2
3107                  | SQLITE_DqsDDL
3108 #endif
3109 
3110 #if !defined(SQLITE_DEFAULT_AUTOMATIC_INDEX) || SQLITE_DEFAULT_AUTOMATIC_INDEX
3111                  | SQLITE_AutoIndex
3112 #endif
3113 #if SQLITE_DEFAULT_CKPTFULLFSYNC
3114                  | SQLITE_CkptFullFSync
3115 #endif
3116 #if SQLITE_DEFAULT_FILE_FORMAT<4
3117                  | SQLITE_LegacyFileFmt
3118 #endif
3119 #ifdef SQLITE_ENABLE_LOAD_EXTENSION
3120                  | SQLITE_LoadExtension
3121 #endif
3122 #if SQLITE_DEFAULT_RECURSIVE_TRIGGERS
3123                  | SQLITE_RecTriggers
3124 #endif
3125 #if defined(SQLITE_DEFAULT_FOREIGN_KEYS) && SQLITE_DEFAULT_FOREIGN_KEYS
3126                  | SQLITE_ForeignKeys
3127 #endif
3128 #if defined(SQLITE_REVERSE_UNORDERED_SELECTS)
3129                  | SQLITE_ReverseOrder
3130 #endif
3131 #if defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
3132                  | SQLITE_CellSizeCk
3133 #endif
3134 #if defined(SQLITE_ENABLE_FTS3_TOKENIZER)
3135                  | SQLITE_Fts3Tokenizer
3136 #endif
3137 #if defined(SQLITE_ENABLE_QPSG)
3138                  | SQLITE_EnableQPSG
3139 #endif
3140 #if defined(SQLITE_DEFAULT_DEFENSIVE)
3141                  | SQLITE_Defensive
3142 #endif
3143       ;
3144   sqlite3HashInit(&db->aCollSeq);
3145 #ifndef SQLITE_OMIT_VIRTUALTABLE
3146   sqlite3HashInit(&db->aModule);
3147 #endif
3148 
3149   /* Add the default collation sequence BINARY. BINARY works for both UTF-8
3150   ** and UTF-16, so add a version for each to avoid any unnecessary
3151   ** conversions. The only error that can occur here is a malloc() failure.
3152   **
3153   ** EVIDENCE-OF: R-52786-44878 SQLite defines three built-in collating
3154   ** functions:
3155   */
3156   createCollation(db, sqlite3StrBINARY, SQLITE_UTF8, 0, binCollFunc, 0);
3157   createCollation(db, sqlite3StrBINARY, SQLITE_UTF16BE, 0, binCollFunc, 0);
3158   createCollation(db, sqlite3StrBINARY, SQLITE_UTF16LE, 0, binCollFunc, 0);
3159   createCollation(db, "NOCASE", SQLITE_UTF8, 0, nocaseCollatingFunc, 0);
3160   createCollation(db, "RTRIM", SQLITE_UTF8, 0, rtrimCollFunc, 0);
3161   if( db->mallocFailed ){
3162     goto opendb_out;
3163   }
3164   /* EVIDENCE-OF: R-08308-17224 The default collating function for all
3165   ** strings is BINARY.
3166   */
3167   db->pDfltColl = sqlite3FindCollSeq(db, SQLITE_UTF8, sqlite3StrBINARY, 0);
3168   assert( db->pDfltColl!=0 );
3169 
3170   /* Parse the filename/URI argument
3171   **
3172   ** Only allow sensible combinations of bits in the flags argument.
3173   ** Throw an error if any non-sense combination is used.  If we
3174   ** do not block illegal combinations here, it could trigger
3175   ** assert() statements in deeper layers.  Sensible combinations
3176   ** are:
3177   **
3178   **  1:  SQLITE_OPEN_READONLY
3179   **  2:  SQLITE_OPEN_READWRITE
3180   **  6:  SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE
3181   */
3182   db->openFlags = flags;
3183   assert( SQLITE_OPEN_READONLY  == 0x01 );
3184   assert( SQLITE_OPEN_READWRITE == 0x02 );
3185   assert( SQLITE_OPEN_CREATE    == 0x04 );
3186   testcase( (1<<(flags&7))==0x02 ); /* READONLY */
3187   testcase( (1<<(flags&7))==0x04 ); /* READWRITE */
3188   testcase( (1<<(flags&7))==0x40 ); /* READWRITE | CREATE */
3189   if( ((1<<(flags&7)) & 0x46)==0 ){
3190     rc = SQLITE_MISUSE_BKPT;  /* IMP: R-65497-44594 */
3191   }else{
3192     rc = sqlite3ParseUri(zVfs, zFilename, &flags, &db->pVfs, &zOpen, &zErrMsg);
3193   }
3194   if( rc!=SQLITE_OK ){
3195     if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
3196     sqlite3ErrorWithMsg(db, rc, zErrMsg ? "%s" : 0, zErrMsg);
3197     sqlite3_free(zErrMsg);
3198     goto opendb_out;
3199   }
3200 
3201   /* Open the backend database driver */
3202   rc = sqlite3BtreeOpen(db->pVfs, zOpen, db, &db->aDb[0].pBt, 0,
3203                         flags | SQLITE_OPEN_MAIN_DB);
3204   if( rc!=SQLITE_OK ){
3205     if( rc==SQLITE_IOERR_NOMEM ){
3206       rc = SQLITE_NOMEM_BKPT;
3207     }
3208     sqlite3Error(db, rc);
3209     goto opendb_out;
3210   }
3211   sqlite3BtreeEnter(db->aDb[0].pBt);
3212   db->aDb[0].pSchema = sqlite3SchemaGet(db, db->aDb[0].pBt);
3213   if( !db->mallocFailed ) ENC(db) = SCHEMA_ENC(db);
3214   sqlite3BtreeLeave(db->aDb[0].pBt);
3215   db->aDb[1].pSchema = sqlite3SchemaGet(db, 0);
3216 
3217   /* The default safety_level for the main database is FULL; for the temp
3218   ** database it is OFF. This matches the pager layer defaults.
3219   */
3220   db->aDb[0].zDbSName = "main";
3221   db->aDb[0].safety_level = SQLITE_DEFAULT_SYNCHRONOUS+1;
3222   db->aDb[1].zDbSName = "temp";
3223   db->aDb[1].safety_level = PAGER_SYNCHRONOUS_OFF;
3224 
3225   db->magic = SQLITE_MAGIC_OPEN;
3226   if( db->mallocFailed ){
3227     goto opendb_out;
3228   }
3229 
3230   /* Register all built-in functions, but do not attempt to read the
3231   ** database schema yet. This is delayed until the first time the database
3232   ** is accessed.
3233   */
3234   sqlite3Error(db, SQLITE_OK);
3235   sqlite3RegisterPerConnectionBuiltinFunctions(db);
3236   rc = sqlite3_errcode(db);
3237 
3238 #ifdef SQLITE_ENABLE_FTS5
3239   /* Register any built-in FTS5 module before loading the automatic
3240   ** extensions. This allows automatic extensions to register FTS5
3241   ** tokenizers and auxiliary functions.  */
3242   if( !db->mallocFailed && rc==SQLITE_OK ){
3243     rc = sqlite3Fts5Init(db);
3244   }
3245 #endif
3246 
3247   /* Load automatic extensions - extensions that have been registered
3248   ** using the sqlite3_automatic_extension() API.
3249   */
3250   if( rc==SQLITE_OK ){
3251     sqlite3AutoLoadExtensions(db);
3252     rc = sqlite3_errcode(db);
3253     if( rc!=SQLITE_OK ){
3254       goto opendb_out;
3255     }
3256   }
3257 
3258 #ifdef SQLITE_ENABLE_FTS1
3259   if( !db->mallocFailed ){
3260     extern int sqlite3Fts1Init(sqlite3*);
3261     rc = sqlite3Fts1Init(db);
3262   }
3263 #endif
3264 
3265 #ifdef SQLITE_ENABLE_FTS2
3266   if( !db->mallocFailed && rc==SQLITE_OK ){
3267     extern int sqlite3Fts2Init(sqlite3*);
3268     rc = sqlite3Fts2Init(db);
3269   }
3270 #endif
3271 
3272 #ifdef SQLITE_ENABLE_FTS3 /* automatically defined by SQLITE_ENABLE_FTS4 */
3273   if( !db->mallocFailed && rc==SQLITE_OK ){
3274     rc = sqlite3Fts3Init(db);
3275   }
3276 #endif
3277 
3278 #if defined(SQLITE_ENABLE_ICU) || defined(SQLITE_ENABLE_ICU_COLLATIONS)
3279   if( !db->mallocFailed && rc==SQLITE_OK ){
3280     rc = sqlite3IcuInit(db);
3281   }
3282 #endif
3283 
3284 #ifdef SQLITE_ENABLE_RTREE
3285   if( !db->mallocFailed && rc==SQLITE_OK){
3286     rc = sqlite3RtreeInit(db);
3287   }
3288 #endif
3289 
3290 #ifdef SQLITE_ENABLE_DBPAGE_VTAB
3291   if( !db->mallocFailed && rc==SQLITE_OK){
3292     rc = sqlite3DbpageRegister(db);
3293   }
3294 #endif
3295 
3296 #ifdef SQLITE_ENABLE_DBSTAT_VTAB
3297   if( !db->mallocFailed && rc==SQLITE_OK){
3298     rc = sqlite3DbstatRegister(db);
3299   }
3300 #endif
3301 
3302 #ifdef SQLITE_ENABLE_JSON1
3303   if( !db->mallocFailed && rc==SQLITE_OK){
3304     rc = sqlite3Json1Init(db);
3305   }
3306 #endif
3307 
3308 #ifdef SQLITE_ENABLE_STMTVTAB
3309   if( !db->mallocFailed && rc==SQLITE_OK){
3310     rc = sqlite3StmtVtabInit(db);
3311   }
3312 #endif
3313 
3314   /* -DSQLITE_DEFAULT_LOCKING_MODE=1 makes EXCLUSIVE the default locking
3315   ** mode.  -DSQLITE_DEFAULT_LOCKING_MODE=0 make NORMAL the default locking
3316   ** mode.  Doing nothing at all also makes NORMAL the default.
3317   */
3318 #ifdef SQLITE_DEFAULT_LOCKING_MODE
3319   db->dfltLockMode = SQLITE_DEFAULT_LOCKING_MODE;
3320   sqlite3PagerLockingMode(sqlite3BtreePager(db->aDb[0].pBt),
3321                           SQLITE_DEFAULT_LOCKING_MODE);
3322 #endif
3323 
3324   if( rc ) sqlite3Error(db, rc);
3325 
3326   /* Enable the lookaside-malloc subsystem */
3327   setupLookaside(db, 0, sqlite3GlobalConfig.szLookaside,
3328                         sqlite3GlobalConfig.nLookaside);
3329 
3330   sqlite3_wal_autocheckpoint(db, SQLITE_DEFAULT_WAL_AUTOCHECKPOINT);
3331 
3332 opendb_out:
3333   if( db ){
3334     assert( db->mutex!=0 || isThreadsafe==0
3335            || sqlite3GlobalConfig.bFullMutex==0 );
3336     sqlite3_mutex_leave(db->mutex);
3337   }
3338   rc = sqlite3_errcode(db);
3339   assert( db!=0 || rc==SQLITE_NOMEM );
3340   if( rc==SQLITE_NOMEM ){
3341     sqlite3_close(db);
3342     db = 0;
3343   }else if( rc!=SQLITE_OK ){
3344     db->magic = SQLITE_MAGIC_SICK;
3345   }
3346   *ppDb = db;
3347 #ifdef SQLITE_ENABLE_SQLLOG
3348   if( sqlite3GlobalConfig.xSqllog ){
3349     /* Opening a db handle. Fourth parameter is passed 0. */
3350     void *pArg = sqlite3GlobalConfig.pSqllogArg;
3351     sqlite3GlobalConfig.xSqllog(pArg, db, zFilename, 0);
3352   }
3353 #endif
3354 #if defined(SQLITE_HAS_CODEC)
3355   if( rc==SQLITE_OK ) sqlite3CodecQueryParameters(db, 0, zOpen);
3356 #endif
3357   sqlite3_free(zOpen);
3358   return rc & 0xff;
3359 }
3360 
3361 
3362 /*
3363 ** Open a new database handle.
3364 */
3365 int sqlite3_open(
3366   const char *zFilename,
3367   sqlite3 **ppDb
3368 ){
3369   return openDatabase(zFilename, ppDb,
3370                       SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0);
3371 }
3372 int sqlite3_open_v2(
3373   const char *filename,   /* Database filename (UTF-8) */
3374   sqlite3 **ppDb,         /* OUT: SQLite db handle */
3375   int flags,              /* Flags */
3376   const char *zVfs        /* Name of VFS module to use */
3377 ){
3378   return openDatabase(filename, ppDb, (unsigned int)flags, zVfs);
3379 }
3380 
3381 #ifndef SQLITE_OMIT_UTF16
3382 /*
3383 ** Open a new database handle.
3384 */
3385 int sqlite3_open16(
3386   const void *zFilename,
3387   sqlite3 **ppDb
3388 ){
3389   char const *zFilename8;   /* zFilename encoded in UTF-8 instead of UTF-16 */
3390   sqlite3_value *pVal;
3391   int rc;
3392 
3393 #ifdef SQLITE_ENABLE_API_ARMOR
3394   if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
3395 #endif
3396   *ppDb = 0;
3397 #ifndef SQLITE_OMIT_AUTOINIT
3398   rc = sqlite3_initialize();
3399   if( rc ) return rc;
3400 #endif
3401   if( zFilename==0 ) zFilename = "\000\000";
3402   pVal = sqlite3ValueNew(0);
3403   sqlite3ValueSetStr(pVal, -1, zFilename, SQLITE_UTF16NATIVE, SQLITE_STATIC);
3404   zFilename8 = sqlite3ValueText(pVal, SQLITE_UTF8);
3405   if( zFilename8 ){
3406     rc = openDatabase(zFilename8, ppDb,
3407                       SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0);
3408     assert( *ppDb || rc==SQLITE_NOMEM );
3409     if( rc==SQLITE_OK && !DbHasProperty(*ppDb, 0, DB_SchemaLoaded) ){
3410       SCHEMA_ENC(*ppDb) = ENC(*ppDb) = SQLITE_UTF16NATIVE;
3411     }
3412   }else{
3413     rc = SQLITE_NOMEM_BKPT;
3414   }
3415   sqlite3ValueFree(pVal);
3416 
3417   return rc & 0xff;
3418 }
3419 #endif /* SQLITE_OMIT_UTF16 */
3420 
3421 /*
3422 ** Register a new collation sequence with the database handle db.
3423 */
3424 int sqlite3_create_collation(
3425   sqlite3* db,
3426   const char *zName,
3427   int enc,
3428   void* pCtx,
3429   int(*xCompare)(void*,int,const void*,int,const void*)
3430 ){
3431   return sqlite3_create_collation_v2(db, zName, enc, pCtx, xCompare, 0);
3432 }
3433 
3434 /*
3435 ** Register a new collation sequence with the database handle db.
3436 */
3437 int sqlite3_create_collation_v2(
3438   sqlite3* db,
3439   const char *zName,
3440   int enc,
3441   void* pCtx,
3442   int(*xCompare)(void*,int,const void*,int,const void*),
3443   void(*xDel)(void*)
3444 ){
3445   int rc;
3446 
3447 #ifdef SQLITE_ENABLE_API_ARMOR
3448   if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
3449 #endif
3450   sqlite3_mutex_enter(db->mutex);
3451   assert( !db->mallocFailed );
3452   rc = createCollation(db, zName, (u8)enc, pCtx, xCompare, xDel);
3453   rc = sqlite3ApiExit(db, rc);
3454   sqlite3_mutex_leave(db->mutex);
3455   return rc;
3456 }
3457 
3458 #ifndef SQLITE_OMIT_UTF16
3459 /*
3460 ** Register a new collation sequence with the database handle db.
3461 */
3462 int sqlite3_create_collation16(
3463   sqlite3* db,
3464   const void *zName,
3465   int enc,
3466   void* pCtx,
3467   int(*xCompare)(void*,int,const void*,int,const void*)
3468 ){
3469   int rc = SQLITE_OK;
3470   char *zName8;
3471 
3472 #ifdef SQLITE_ENABLE_API_ARMOR
3473   if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
3474 #endif
3475   sqlite3_mutex_enter(db->mutex);
3476   assert( !db->mallocFailed );
3477   zName8 = sqlite3Utf16to8(db, zName, -1, SQLITE_UTF16NATIVE);
3478   if( zName8 ){
3479     rc = createCollation(db, zName8, (u8)enc, pCtx, xCompare, 0);
3480     sqlite3DbFree(db, zName8);
3481   }
3482   rc = sqlite3ApiExit(db, rc);
3483   sqlite3_mutex_leave(db->mutex);
3484   return rc;
3485 }
3486 #endif /* SQLITE_OMIT_UTF16 */
3487 
3488 /*
3489 ** Register a collation sequence factory callback with the database handle
3490 ** db. Replace any previously installed collation sequence factory.
3491 */
3492 int sqlite3_collation_needed(
3493   sqlite3 *db,
3494   void *pCollNeededArg,
3495   void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*)
3496 ){
3497 #ifdef SQLITE_ENABLE_API_ARMOR
3498   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3499 #endif
3500   sqlite3_mutex_enter(db->mutex);
3501   db->xCollNeeded = xCollNeeded;
3502   db->xCollNeeded16 = 0;
3503   db->pCollNeededArg = pCollNeededArg;
3504   sqlite3_mutex_leave(db->mutex);
3505   return SQLITE_OK;
3506 }
3507 
3508 #ifndef SQLITE_OMIT_UTF16
3509 /*
3510 ** Register a collation sequence factory callback with the database handle
3511 ** db. Replace any previously installed collation sequence factory.
3512 */
3513 int sqlite3_collation_needed16(
3514   sqlite3 *db,
3515   void *pCollNeededArg,
3516   void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*)
3517 ){
3518 #ifdef SQLITE_ENABLE_API_ARMOR
3519   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3520 #endif
3521   sqlite3_mutex_enter(db->mutex);
3522   db->xCollNeeded = 0;
3523   db->xCollNeeded16 = xCollNeeded16;
3524   db->pCollNeededArg = pCollNeededArg;
3525   sqlite3_mutex_leave(db->mutex);
3526   return SQLITE_OK;
3527 }
3528 #endif /* SQLITE_OMIT_UTF16 */
3529 
3530 #ifndef SQLITE_OMIT_DEPRECATED
3531 /*
3532 ** This function is now an anachronism. It used to be used to recover from a
3533 ** malloc() failure, but SQLite now does this automatically.
3534 */
3535 int sqlite3_global_recover(void){
3536   return SQLITE_OK;
3537 }
3538 #endif
3539 
3540 /*
3541 ** Test to see whether or not the database connection is in autocommit
3542 ** mode.  Return TRUE if it is and FALSE if not.  Autocommit mode is on
3543 ** by default.  Autocommit is disabled by a BEGIN statement and reenabled
3544 ** by the next COMMIT or ROLLBACK.
3545 */
3546 int sqlite3_get_autocommit(sqlite3 *db){
3547 #ifdef SQLITE_ENABLE_API_ARMOR
3548   if( !sqlite3SafetyCheckOk(db) ){
3549     (void)SQLITE_MISUSE_BKPT;
3550     return 0;
3551   }
3552 #endif
3553   return db->autoCommit;
3554 }
3555 
3556 /*
3557 ** The following routines are substitutes for constants SQLITE_CORRUPT,
3558 ** SQLITE_MISUSE, SQLITE_CANTOPEN, SQLITE_NOMEM and possibly other error
3559 ** constants.  They serve two purposes:
3560 **
3561 **   1.  Serve as a convenient place to set a breakpoint in a debugger
3562 **       to detect when version error conditions occurs.
3563 **
3564 **   2.  Invoke sqlite3_log() to provide the source code location where
3565 **       a low-level error is first detected.
3566 */
3567 int sqlite3ReportError(int iErr, int lineno, const char *zType){
3568   sqlite3_log(iErr, "%s at line %d of [%.10s]",
3569               zType, lineno, 20+sqlite3_sourceid());
3570   return iErr;
3571 }
3572 int sqlite3CorruptError(int lineno){
3573   testcase( sqlite3GlobalConfig.xLog!=0 );
3574   return sqlite3ReportError(SQLITE_CORRUPT, lineno, "database corruption");
3575 }
3576 int sqlite3MisuseError(int lineno){
3577   testcase( sqlite3GlobalConfig.xLog!=0 );
3578   return sqlite3ReportError(SQLITE_MISUSE, lineno, "misuse");
3579 }
3580 int sqlite3CantopenError(int lineno){
3581   testcase( sqlite3GlobalConfig.xLog!=0 );
3582   return sqlite3ReportError(SQLITE_CANTOPEN, lineno, "cannot open file");
3583 }
3584 #ifdef SQLITE_DEBUG
3585 int sqlite3CorruptPgnoError(int lineno, Pgno pgno){
3586   char zMsg[100];
3587   sqlite3_snprintf(sizeof(zMsg), zMsg, "database corruption page %d", pgno);
3588   testcase( sqlite3GlobalConfig.xLog!=0 );
3589   return sqlite3ReportError(SQLITE_CORRUPT, lineno, zMsg);
3590 }
3591 int sqlite3NomemError(int lineno){
3592   testcase( sqlite3GlobalConfig.xLog!=0 );
3593   return sqlite3ReportError(SQLITE_NOMEM, lineno, "OOM");
3594 }
3595 int sqlite3IoerrnomemError(int lineno){
3596   testcase( sqlite3GlobalConfig.xLog!=0 );
3597   return sqlite3ReportError(SQLITE_IOERR_NOMEM, lineno, "I/O OOM error");
3598 }
3599 #endif
3600 
3601 #ifndef SQLITE_OMIT_DEPRECATED
3602 /*
3603 ** This is a convenience routine that makes sure that all thread-specific
3604 ** data for this thread has been deallocated.
3605 **
3606 ** SQLite no longer uses thread-specific data so this routine is now a
3607 ** no-op.  It is retained for historical compatibility.
3608 */
3609 void sqlite3_thread_cleanup(void){
3610 }
3611 #endif
3612 
3613 /*
3614 ** Return meta information about a specific column of a database table.
3615 ** See comment in sqlite3.h (sqlite.h.in) for details.
3616 */
3617 int sqlite3_table_column_metadata(
3618   sqlite3 *db,                /* Connection handle */
3619   const char *zDbName,        /* Database name or NULL */
3620   const char *zTableName,     /* Table name */
3621   const char *zColumnName,    /* Column name */
3622   char const **pzDataType,    /* OUTPUT: Declared data type */
3623   char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
3624   int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
3625   int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
3626   int *pAutoinc               /* OUTPUT: True if column is auto-increment */
3627 ){
3628   int rc;
3629   char *zErrMsg = 0;
3630   Table *pTab = 0;
3631   Column *pCol = 0;
3632   int iCol = 0;
3633   char const *zDataType = 0;
3634   char const *zCollSeq = 0;
3635   int notnull = 0;
3636   int primarykey = 0;
3637   int autoinc = 0;
3638 
3639 
3640 #ifdef SQLITE_ENABLE_API_ARMOR
3641   if( !sqlite3SafetyCheckOk(db) || zTableName==0 ){
3642     return SQLITE_MISUSE_BKPT;
3643   }
3644 #endif
3645 
3646   /* Ensure the database schema has been loaded */
3647   sqlite3_mutex_enter(db->mutex);
3648   sqlite3BtreeEnterAll(db);
3649   rc = sqlite3Init(db, &zErrMsg);
3650   if( SQLITE_OK!=rc ){
3651     goto error_out;
3652   }
3653 
3654   /* Locate the table in question */
3655   pTab = sqlite3FindTable(db, zTableName, zDbName);
3656   if( !pTab || pTab->pSelect ){
3657     pTab = 0;
3658     goto error_out;
3659   }
3660 
3661   /* Find the column for which info is requested */
3662   if( zColumnName==0 ){
3663     /* Query for existance of table only */
3664   }else{
3665     for(iCol=0; iCol<pTab->nCol; iCol++){
3666       pCol = &pTab->aCol[iCol];
3667       if( 0==sqlite3StrICmp(pCol->zName, zColumnName) ){
3668         break;
3669       }
3670     }
3671     if( iCol==pTab->nCol ){
3672       if( HasRowid(pTab) && sqlite3IsRowid(zColumnName) ){
3673         iCol = pTab->iPKey;
3674         pCol = iCol>=0 ? &pTab->aCol[iCol] : 0;
3675       }else{
3676         pTab = 0;
3677         goto error_out;
3678       }
3679     }
3680   }
3681 
3682   /* The following block stores the meta information that will be returned
3683   ** to the caller in local variables zDataType, zCollSeq, notnull, primarykey
3684   ** and autoinc. At this point there are two possibilities:
3685   **
3686   **     1. The specified column name was rowid", "oid" or "_rowid_"
3687   **        and there is no explicitly declared IPK column.
3688   **
3689   **     2. The table is not a view and the column name identified an
3690   **        explicitly declared column. Copy meta information from *pCol.
3691   */
3692   if( pCol ){
3693     zDataType = sqlite3ColumnType(pCol,0);
3694     zCollSeq = pCol->zColl;
3695     notnull = pCol->notNull!=0;
3696     primarykey  = (pCol->colFlags & COLFLAG_PRIMKEY)!=0;
3697     autoinc = pTab->iPKey==iCol && (pTab->tabFlags & TF_Autoincrement)!=0;
3698   }else{
3699     zDataType = "INTEGER";
3700     primarykey = 1;
3701   }
3702   if( !zCollSeq ){
3703     zCollSeq = sqlite3StrBINARY;
3704   }
3705 
3706 error_out:
3707   sqlite3BtreeLeaveAll(db);
3708 
3709   /* Whether the function call succeeded or failed, set the output parameters
3710   ** to whatever their local counterparts contain. If an error did occur,
3711   ** this has the effect of zeroing all output parameters.
3712   */
3713   if( pzDataType ) *pzDataType = zDataType;
3714   if( pzCollSeq ) *pzCollSeq = zCollSeq;
3715   if( pNotNull ) *pNotNull = notnull;
3716   if( pPrimaryKey ) *pPrimaryKey = primarykey;
3717   if( pAutoinc ) *pAutoinc = autoinc;
3718 
3719   if( SQLITE_OK==rc && !pTab ){
3720     sqlite3DbFree(db, zErrMsg);
3721     zErrMsg = sqlite3MPrintf(db, "no such table column: %s.%s", zTableName,
3722         zColumnName);
3723     rc = SQLITE_ERROR;
3724   }
3725   sqlite3ErrorWithMsg(db, rc, (zErrMsg?"%s":0), zErrMsg);
3726   sqlite3DbFree(db, zErrMsg);
3727   rc = sqlite3ApiExit(db, rc);
3728   sqlite3_mutex_leave(db->mutex);
3729   return rc;
3730 }
3731 
3732 /*
3733 ** Sleep for a little while.  Return the amount of time slept.
3734 */
3735 int sqlite3_sleep(int ms){
3736   sqlite3_vfs *pVfs;
3737   int rc;
3738   pVfs = sqlite3_vfs_find(0);
3739   if( pVfs==0 ) return 0;
3740 
3741   /* This function works in milliseconds, but the underlying OsSleep()
3742   ** API uses microseconds. Hence the 1000's.
3743   */
3744   rc = (sqlite3OsSleep(pVfs, 1000*ms)/1000);
3745   return rc;
3746 }
3747 
3748 /*
3749 ** Enable or disable the extended result codes.
3750 */
3751 int sqlite3_extended_result_codes(sqlite3 *db, int onoff){
3752 #ifdef SQLITE_ENABLE_API_ARMOR
3753   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3754 #endif
3755   sqlite3_mutex_enter(db->mutex);
3756   db->errMask = onoff ? 0xffffffff : 0xff;
3757   sqlite3_mutex_leave(db->mutex);
3758   return SQLITE_OK;
3759 }
3760 
3761 /*
3762 ** Invoke the xFileControl method on a particular database.
3763 */
3764 int sqlite3_file_control(sqlite3 *db, const char *zDbName, int op, void *pArg){
3765   int rc = SQLITE_ERROR;
3766   Btree *pBtree;
3767 
3768 #ifdef SQLITE_ENABLE_API_ARMOR
3769   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3770 #endif
3771   sqlite3_mutex_enter(db->mutex);
3772   pBtree = sqlite3DbNameToBtree(db, zDbName);
3773   if( pBtree ){
3774     Pager *pPager;
3775     sqlite3_file *fd;
3776     sqlite3BtreeEnter(pBtree);
3777     pPager = sqlite3BtreePager(pBtree);
3778     assert( pPager!=0 );
3779     fd = sqlite3PagerFile(pPager);
3780     assert( fd!=0 );
3781     if( op==SQLITE_FCNTL_FILE_POINTER ){
3782       *(sqlite3_file**)pArg = fd;
3783       rc = SQLITE_OK;
3784     }else if( op==SQLITE_FCNTL_VFS_POINTER ){
3785       *(sqlite3_vfs**)pArg = sqlite3PagerVfs(pPager);
3786       rc = SQLITE_OK;
3787     }else if( op==SQLITE_FCNTL_JOURNAL_POINTER ){
3788       *(sqlite3_file**)pArg = sqlite3PagerJrnlFile(pPager);
3789       rc = SQLITE_OK;
3790     }else if( op==SQLITE_FCNTL_DATA_VERSION ){
3791       *(unsigned int*)pArg = sqlite3PagerDataVersion(pPager);
3792       rc = SQLITE_OK;
3793     }else{
3794       rc = sqlite3OsFileControl(fd, op, pArg);
3795     }
3796     sqlite3BtreeLeave(pBtree);
3797   }
3798   sqlite3_mutex_leave(db->mutex);
3799   return rc;
3800 }
3801 
3802 /*
3803 ** Interface to the testing logic.
3804 */
3805 int sqlite3_test_control(int op, ...){
3806   int rc = 0;
3807 #ifdef SQLITE_UNTESTABLE
3808   UNUSED_PARAMETER(op);
3809 #else
3810   va_list ap;
3811   va_start(ap, op);
3812   switch( op ){
3813 
3814     /*
3815     ** Save the current state of the PRNG.
3816     */
3817     case SQLITE_TESTCTRL_PRNG_SAVE: {
3818       sqlite3PrngSaveState();
3819       break;
3820     }
3821 
3822     /*
3823     ** Restore the state of the PRNG to the last state saved using
3824     ** PRNG_SAVE.  If PRNG_SAVE has never before been called, then
3825     ** this verb acts like PRNG_RESET.
3826     */
3827     case SQLITE_TESTCTRL_PRNG_RESTORE: {
3828       sqlite3PrngRestoreState();
3829       break;
3830     }
3831 
3832     /*  sqlite3_test_control(SQLITE_TESTCTRL_PRNG_SEED, int x, sqlite3 *db);
3833     **
3834     ** Control the seed for the pseudo-random number generator (PRNG) that
3835     ** is built into SQLite.  Cases:
3836     **
3837     **    x!=0 && db!=0       Seed the PRNG to the current value of the
3838     **                        schema cookie in the main database for db, or
3839     **                        x if the schema cookie is zero.  This case
3840     **                        is convenient to use with database fuzzers
3841     **                        as it allows the fuzzer some control over the
3842     **                        the PRNG seed.
3843     **
3844     **    x!=0 && db==0       Seed the PRNG to the value of x.
3845     **
3846     **    x==0 && db==0       Revert to default behavior of using the
3847     **                        xRandomness method on the primary VFS.
3848     **
3849     ** This test-control also resets the PRNG so that the new seed will
3850     ** be used for the next call to sqlite3_randomness().
3851     */
3852     case SQLITE_TESTCTRL_PRNG_SEED: {
3853       int x = va_arg(ap, int);
3854       int y;
3855       sqlite3 *db = va_arg(ap, sqlite3*);
3856       assert( db==0 || db->aDb[0].pSchema!=0 );
3857       if( db && (y = db->aDb[0].pSchema->schema_cookie)!=0 ){ x = y; }
3858       sqlite3Config.iPrngSeed = x;
3859       sqlite3_randomness(0,0);
3860       break;
3861     }
3862 
3863     /*
3864     **  sqlite3_test_control(BITVEC_TEST, size, program)
3865     **
3866     ** Run a test against a Bitvec object of size.  The program argument
3867     ** is an array of integers that defines the test.  Return -1 on a
3868     ** memory allocation error, 0 on success, or non-zero for an error.
3869     ** See the sqlite3BitvecBuiltinTest() for additional information.
3870     */
3871     case SQLITE_TESTCTRL_BITVEC_TEST: {
3872       int sz = va_arg(ap, int);
3873       int *aProg = va_arg(ap, int*);
3874       rc = sqlite3BitvecBuiltinTest(sz, aProg);
3875       break;
3876     }
3877 
3878     /*
3879     **  sqlite3_test_control(FAULT_INSTALL, xCallback)
3880     **
3881     ** Arrange to invoke xCallback() whenever sqlite3FaultSim() is called,
3882     ** if xCallback is not NULL.
3883     **
3884     ** As a test of the fault simulator mechanism itself, sqlite3FaultSim(0)
3885     ** is called immediately after installing the new callback and the return
3886     ** value from sqlite3FaultSim(0) becomes the return from
3887     ** sqlite3_test_control().
3888     */
3889     case SQLITE_TESTCTRL_FAULT_INSTALL: {
3890       /* MSVC is picky about pulling func ptrs from va lists.
3891       ** http://support.microsoft.com/kb/47961
3892       ** sqlite3GlobalConfig.xTestCallback = va_arg(ap, int(*)(int));
3893       */
3894       typedef int(*TESTCALLBACKFUNC_t)(int);
3895       sqlite3GlobalConfig.xTestCallback = va_arg(ap, TESTCALLBACKFUNC_t);
3896       rc = sqlite3FaultSim(0);
3897       break;
3898     }
3899 
3900     /*
3901     **  sqlite3_test_control(BENIGN_MALLOC_HOOKS, xBegin, xEnd)
3902     **
3903     ** Register hooks to call to indicate which malloc() failures
3904     ** are benign.
3905     */
3906     case SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS: {
3907       typedef void (*void_function)(void);
3908       void_function xBenignBegin;
3909       void_function xBenignEnd;
3910       xBenignBegin = va_arg(ap, void_function);
3911       xBenignEnd = va_arg(ap, void_function);
3912       sqlite3BenignMallocHooks(xBenignBegin, xBenignEnd);
3913       break;
3914     }
3915 
3916     /*
3917     **  sqlite3_test_control(SQLITE_TESTCTRL_PENDING_BYTE, unsigned int X)
3918     **
3919     ** Set the PENDING byte to the value in the argument, if X>0.
3920     ** Make no changes if X==0.  Return the value of the pending byte
3921     ** as it existing before this routine was called.
3922     **
3923     ** IMPORTANT:  Changing the PENDING byte from 0x40000000 results in
3924     ** an incompatible database file format.  Changing the PENDING byte
3925     ** while any database connection is open results in undefined and
3926     ** deleterious behavior.
3927     */
3928     case SQLITE_TESTCTRL_PENDING_BYTE: {
3929       rc = PENDING_BYTE;
3930 #ifndef SQLITE_OMIT_WSD
3931       {
3932         unsigned int newVal = va_arg(ap, unsigned int);
3933         if( newVal ) sqlite3PendingByte = newVal;
3934       }
3935 #endif
3936       break;
3937     }
3938 
3939     /*
3940     **  sqlite3_test_control(SQLITE_TESTCTRL_ASSERT, int X)
3941     **
3942     ** This action provides a run-time test to see whether or not
3943     ** assert() was enabled at compile-time.  If X is true and assert()
3944     ** is enabled, then the return value is true.  If X is true and
3945     ** assert() is disabled, then the return value is zero.  If X is
3946     ** false and assert() is enabled, then the assertion fires and the
3947     ** process aborts.  If X is false and assert() is disabled, then the
3948     ** return value is zero.
3949     */
3950     case SQLITE_TESTCTRL_ASSERT: {
3951       volatile int x = 0;
3952       assert( /*side-effects-ok*/ (x = va_arg(ap,int))!=0 );
3953       rc = x;
3954       break;
3955     }
3956 
3957 
3958     /*
3959     **  sqlite3_test_control(SQLITE_TESTCTRL_ALWAYS, int X)
3960     **
3961     ** This action provides a run-time test to see how the ALWAYS and
3962     ** NEVER macros were defined at compile-time.
3963     **
3964     ** The return value is ALWAYS(X) if X is true, or 0 if X is false.
3965     **
3966     ** The recommended test is X==2.  If the return value is 2, that means
3967     ** ALWAYS() and NEVER() are both no-op pass-through macros, which is the
3968     ** default setting.  If the return value is 1, then ALWAYS() is either
3969     ** hard-coded to true or else it asserts if its argument is false.
3970     ** The first behavior (hard-coded to true) is the case if
3971     ** SQLITE_TESTCTRL_ASSERT shows that assert() is disabled and the second
3972     ** behavior (assert if the argument to ALWAYS() is false) is the case if
3973     ** SQLITE_TESTCTRL_ASSERT shows that assert() is enabled.
3974     **
3975     ** The run-time test procedure might look something like this:
3976     **
3977     **    if( sqlite3_test_control(SQLITE_TESTCTRL_ALWAYS, 2)==2 ){
3978     **      // ALWAYS() and NEVER() are no-op pass-through macros
3979     **    }else if( sqlite3_test_control(SQLITE_TESTCTRL_ASSERT, 1) ){
3980     **      // ALWAYS(x) asserts that x is true. NEVER(x) asserts x is false.
3981     **    }else{
3982     **      // ALWAYS(x) is a constant 1.  NEVER(x) is a constant 0.
3983     **    }
3984     */
3985     case SQLITE_TESTCTRL_ALWAYS: {
3986       int x = va_arg(ap,int);
3987       rc = x ? ALWAYS(x) : 0;
3988       break;
3989     }
3990 
3991     /*
3992     **   sqlite3_test_control(SQLITE_TESTCTRL_BYTEORDER);
3993     **
3994     ** The integer returned reveals the byte-order of the computer on which
3995     ** SQLite is running:
3996     **
3997     **       1     big-endian,    determined at run-time
3998     **      10     little-endian, determined at run-time
3999     **  432101     big-endian,    determined at compile-time
4000     **  123410     little-endian, determined at compile-time
4001     */
4002     case SQLITE_TESTCTRL_BYTEORDER: {
4003       rc = SQLITE_BYTEORDER*100 + SQLITE_LITTLEENDIAN*10 + SQLITE_BIGENDIAN;
4004       break;
4005     }
4006 
4007     /*   sqlite3_test_control(SQLITE_TESTCTRL_RESERVE, sqlite3 *db, int N)
4008     **
4009     ** Set the nReserve size to N for the main database on the database
4010     ** connection db.
4011     */
4012     case SQLITE_TESTCTRL_RESERVE: {
4013       sqlite3 *db = va_arg(ap, sqlite3*);
4014       int x = va_arg(ap,int);
4015       sqlite3_mutex_enter(db->mutex);
4016       sqlite3BtreeSetPageSize(db->aDb[0].pBt, 0, x, 0);
4017       sqlite3_mutex_leave(db->mutex);
4018       break;
4019     }
4020 
4021     /*  sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS, sqlite3 *db, int N)
4022     **
4023     ** Enable or disable various optimizations for testing purposes.  The
4024     ** argument N is a bitmask of optimizations to be disabled.  For normal
4025     ** operation N should be 0.  The idea is that a test program (like the
4026     ** SQL Logic Test or SLT test module) can run the same SQL multiple times
4027     ** with various optimizations disabled to verify that the same answer
4028     ** is obtained in every case.
4029     */
4030     case SQLITE_TESTCTRL_OPTIMIZATIONS: {
4031       sqlite3 *db = va_arg(ap, sqlite3*);
4032       db->dbOptFlags = (u16)(va_arg(ap, int) & 0xffff);
4033       break;
4034     }
4035 
4036     /*   sqlite3_test_control(SQLITE_TESTCTRL_LOCALTIME_FAULT, int onoff);
4037     **
4038     ** If parameter onoff is non-zero, subsequent calls to localtime()
4039     ** and its variants fail. If onoff is zero, undo this setting.
4040     */
4041     case SQLITE_TESTCTRL_LOCALTIME_FAULT: {
4042       sqlite3GlobalConfig.bLocaltimeFault = va_arg(ap, int);
4043       break;
4044     }
4045 
4046     /*   sqlite3_test_control(SQLITE_TESTCTRL_INTERNAL_FUNCS, int onoff);
4047     **
4048     ** If parameter onoff is non-zero, internal-use-only SQL functions
4049     ** are visible to ordinary SQL.  This is useful for testing but is
4050     ** unsafe because invalid parameters to those internal-use-only functions
4051     ** can result in crashes or segfaults.
4052     */
4053     case SQLITE_TESTCTRL_INTERNAL_FUNCTIONS: {
4054       sqlite3GlobalConfig.bInternalFunctions = va_arg(ap, int);
4055       break;
4056     }
4057 
4058     /*   sqlite3_test_control(SQLITE_TESTCTRL_NEVER_CORRUPT, int);
4059     **
4060     ** Set or clear a flag that indicates that the database file is always well-
4061     ** formed and never corrupt.  This flag is clear by default, indicating that
4062     ** database files might have arbitrary corruption.  Setting the flag during
4063     ** testing causes certain assert() statements in the code to be activated
4064     ** that demonstrat invariants on well-formed database files.
4065     */
4066     case SQLITE_TESTCTRL_NEVER_CORRUPT: {
4067       sqlite3GlobalConfig.neverCorrupt = va_arg(ap, int);
4068       break;
4069     }
4070 
4071     /*   sqlite3_test_control(SQLITE_TESTCTRL_EXTRA_SCHEMA_CHECKS, int);
4072     **
4073     ** Set or clear a flag that causes SQLite to verify that type, name,
4074     ** and tbl_name fields of the sqlite_master table.  This is normally
4075     ** on, but it is sometimes useful to turn it off for testing.
4076     */
4077     case SQLITE_TESTCTRL_EXTRA_SCHEMA_CHECKS: {
4078       sqlite3GlobalConfig.bExtraSchemaChecks = va_arg(ap, int);
4079       break;
4080     }
4081 
4082     /* Set the threshold at which OP_Once counters reset back to zero.
4083     ** By default this is 0x7ffffffe (over 2 billion), but that value is
4084     ** too big to test in a reasonable amount of time, so this control is
4085     ** provided to set a small and easily reachable reset value.
4086     */
4087     case SQLITE_TESTCTRL_ONCE_RESET_THRESHOLD: {
4088       sqlite3GlobalConfig.iOnceResetThreshold = va_arg(ap, int);
4089       break;
4090     }
4091 
4092     /*   sqlite3_test_control(SQLITE_TESTCTRL_VDBE_COVERAGE, xCallback, ptr);
4093     **
4094     ** Set the VDBE coverage callback function to xCallback with context
4095     ** pointer ptr.
4096     */
4097     case SQLITE_TESTCTRL_VDBE_COVERAGE: {
4098 #ifdef SQLITE_VDBE_COVERAGE
4099       typedef void (*branch_callback)(void*,unsigned int,
4100                                       unsigned char,unsigned char);
4101       sqlite3GlobalConfig.xVdbeBranch = va_arg(ap,branch_callback);
4102       sqlite3GlobalConfig.pVdbeBranchArg = va_arg(ap,void*);
4103 #endif
4104       break;
4105     }
4106 
4107     /*   sqlite3_test_control(SQLITE_TESTCTRL_SORTER_MMAP, db, nMax); */
4108     case SQLITE_TESTCTRL_SORTER_MMAP: {
4109       sqlite3 *db = va_arg(ap, sqlite3*);
4110       db->nMaxSorterMmap = va_arg(ap, int);
4111       break;
4112     }
4113 
4114     /*   sqlite3_test_control(SQLITE_TESTCTRL_ISINIT);
4115     **
4116     ** Return SQLITE_OK if SQLite has been initialized and SQLITE_ERROR if
4117     ** not.
4118     */
4119     case SQLITE_TESTCTRL_ISINIT: {
4120       if( sqlite3GlobalConfig.isInit==0 ) rc = SQLITE_ERROR;
4121       break;
4122     }
4123 
4124     /*  sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, db, dbName, onOff, tnum);
4125     **
4126     ** This test control is used to create imposter tables.  "db" is a pointer
4127     ** to the database connection.  dbName is the database name (ex: "main" or
4128     ** "temp") which will receive the imposter.  "onOff" turns imposter mode on
4129     ** or off.  "tnum" is the root page of the b-tree to which the imposter
4130     ** table should connect.
4131     **
4132     ** Enable imposter mode only when the schema has already been parsed.  Then
4133     ** run a single CREATE TABLE statement to construct the imposter table in
4134     ** the parsed schema.  Then turn imposter mode back off again.
4135     **
4136     ** If onOff==0 and tnum>0 then reset the schema for all databases, causing
4137     ** the schema to be reparsed the next time it is needed.  This has the
4138     ** effect of erasing all imposter tables.
4139     */
4140     case SQLITE_TESTCTRL_IMPOSTER: {
4141       sqlite3 *db = va_arg(ap, sqlite3*);
4142       sqlite3_mutex_enter(db->mutex);
4143       db->init.iDb = sqlite3FindDbName(db, va_arg(ap,const char*));
4144       db->init.busy = db->init.imposterTable = va_arg(ap,int);
4145       db->init.newTnum = va_arg(ap,int);
4146       if( db->init.busy==0 && db->init.newTnum>0 ){
4147         sqlite3ResetAllSchemasOfConnection(db);
4148       }
4149       sqlite3_mutex_leave(db->mutex);
4150       break;
4151     }
4152 
4153 #if defined(YYCOVERAGE)
4154     /*  sqlite3_test_control(SQLITE_TESTCTRL_PARSER_COVERAGE, FILE *out)
4155     **
4156     ** This test control (only available when SQLite is compiled with
4157     ** -DYYCOVERAGE) writes a report onto "out" that shows all
4158     ** state/lookahead combinations in the parser state machine
4159     ** which are never exercised.  If any state is missed, make the
4160     ** return code SQLITE_ERROR.
4161     */
4162     case SQLITE_TESTCTRL_PARSER_COVERAGE: {
4163       FILE *out = va_arg(ap, FILE*);
4164       if( sqlite3ParserCoverage(out) ) rc = SQLITE_ERROR;
4165       break;
4166     }
4167 #endif /* defined(YYCOVERAGE) */
4168 
4169     /*  sqlite3_test_control(SQLITE_TESTCTRL_RESULT_INTREAL, sqlite3_context*);
4170     **
4171     ** This test-control causes the most recent sqlite3_result_int64() value
4172     ** to be interpreted as a MEM_IntReal instead of as an MEM_Int.  Normally,
4173     ** MEM_IntReal values only arise during an INSERT operation of integer
4174     ** values into a REAL column, so they can be challenging to test.  This
4175     ** test-control enables us to write an intreal() SQL function that can
4176     ** inject an intreal() value at arbitrary places in an SQL statement,
4177     ** for testing purposes.
4178     */
4179     case SQLITE_TESTCTRL_RESULT_INTREAL: {
4180       sqlite3_context *pCtx = va_arg(ap, sqlite3_context*);
4181       sqlite3ResultIntReal(pCtx);
4182       break;
4183     }
4184   }
4185   va_end(ap);
4186 #endif /* SQLITE_UNTESTABLE */
4187   return rc;
4188 }
4189 
4190 #ifdef SQLITE_DEBUG
4191 /*
4192 ** This routine appears inside assert() statements only.
4193 **
4194 ** Return the number of URI parameters that follow the filename.
4195 */
4196 int sqlite3UriCount(const char *z){
4197   int n = 0;
4198   if( z==0 ) return 0;
4199   z += strlen(z)+1;
4200   while( z[0] ){
4201     z += strlen(z)+1;
4202     z += strlen(z)+1;
4203     n++;
4204   }
4205   return n;
4206 }
4207 #endif /* SQLITE_DEBUG */
4208 
4209 /*
4210 ** This is a utility routine, useful to VFS implementations, that checks
4211 ** to see if a database file was a URI that contained a specific query
4212 ** parameter, and if so obtains the value of the query parameter.
4213 **
4214 ** The zFilename argument is the filename pointer passed into the xOpen()
4215 ** method of a VFS implementation.  The zParam argument is the name of the
4216 ** query parameter we seek.  This routine returns the value of the zParam
4217 ** parameter if it exists.  If the parameter does not exist, this routine
4218 ** returns a NULL pointer.
4219 */
4220 const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam){
4221   if( zFilename==0 || zParam==0 ) return 0;
4222   zFilename += sqlite3Strlen30(zFilename) + 1;
4223   while( zFilename[0] ){
4224     int x = strcmp(zFilename, zParam);
4225     zFilename += sqlite3Strlen30(zFilename) + 1;
4226     if( x==0 ) return zFilename;
4227     zFilename += sqlite3Strlen30(zFilename) + 1;
4228   }
4229   return 0;
4230 }
4231 
4232 /*
4233 ** Return a boolean value for a query parameter.
4234 */
4235 int sqlite3_uri_boolean(const char *zFilename, const char *zParam, int bDflt){
4236   const char *z = sqlite3_uri_parameter(zFilename, zParam);
4237   bDflt = bDflt!=0;
4238   return z ? sqlite3GetBoolean(z, bDflt) : bDflt;
4239 }
4240 
4241 /*
4242 ** Return a 64-bit integer value for a query parameter.
4243 */
4244 sqlite3_int64 sqlite3_uri_int64(
4245   const char *zFilename,    /* Filename as passed to xOpen */
4246   const char *zParam,       /* URI parameter sought */
4247   sqlite3_int64 bDflt       /* return if parameter is missing */
4248 ){
4249   const char *z = sqlite3_uri_parameter(zFilename, zParam);
4250   sqlite3_int64 v;
4251   if( z && sqlite3DecOrHexToI64(z, &v)==0 ){
4252     bDflt = v;
4253   }
4254   return bDflt;
4255 }
4256 
4257 /*
4258 ** Return the Btree pointer identified by zDbName.  Return NULL if not found.
4259 */
4260 Btree *sqlite3DbNameToBtree(sqlite3 *db, const char *zDbName){
4261   int iDb = zDbName ? sqlite3FindDbName(db, zDbName) : 0;
4262   return iDb<0 ? 0 : db->aDb[iDb].pBt;
4263 }
4264 
4265 /*
4266 ** Return the filename of the database associated with a database
4267 ** connection.
4268 */
4269 const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName){
4270   Btree *pBt;
4271 #ifdef SQLITE_ENABLE_API_ARMOR
4272   if( !sqlite3SafetyCheckOk(db) ){
4273     (void)SQLITE_MISUSE_BKPT;
4274     return 0;
4275   }
4276 #endif
4277   pBt = sqlite3DbNameToBtree(db, zDbName);
4278   return pBt ? sqlite3BtreeGetFilename(pBt) : 0;
4279 }
4280 
4281 /*
4282 ** Return 1 if database is read-only or 0 if read/write.  Return -1 if
4283 ** no such database exists.
4284 */
4285 int sqlite3_db_readonly(sqlite3 *db, const char *zDbName){
4286   Btree *pBt;
4287 #ifdef SQLITE_ENABLE_API_ARMOR
4288   if( !sqlite3SafetyCheckOk(db) ){
4289     (void)SQLITE_MISUSE_BKPT;
4290     return -1;
4291   }
4292 #endif
4293   pBt = sqlite3DbNameToBtree(db, zDbName);
4294   return pBt ? sqlite3BtreeIsReadonly(pBt) : -1;
4295 }
4296 
4297 #ifdef SQLITE_ENABLE_SNAPSHOT
4298 /*
4299 ** Obtain a snapshot handle for the snapshot of database zDb currently
4300 ** being read by handle db.
4301 */
4302 int sqlite3_snapshot_get(
4303   sqlite3 *db,
4304   const char *zDb,
4305   sqlite3_snapshot **ppSnapshot
4306 ){
4307   int rc = SQLITE_ERROR;
4308 #ifndef SQLITE_OMIT_WAL
4309 
4310 #ifdef SQLITE_ENABLE_API_ARMOR
4311   if( !sqlite3SafetyCheckOk(db) ){
4312     return SQLITE_MISUSE_BKPT;
4313   }
4314 #endif
4315   sqlite3_mutex_enter(db->mutex);
4316 
4317   if( db->autoCommit==0 ){
4318     int iDb = sqlite3FindDbName(db, zDb);
4319     if( iDb==0 || iDb>1 ){
4320       Btree *pBt = db->aDb[iDb].pBt;
4321       if( 0==sqlite3BtreeIsInTrans(pBt) ){
4322         rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
4323         if( rc==SQLITE_OK ){
4324           rc = sqlite3PagerSnapshotGet(sqlite3BtreePager(pBt), ppSnapshot);
4325         }
4326       }
4327     }
4328   }
4329 
4330   sqlite3_mutex_leave(db->mutex);
4331 #endif   /* SQLITE_OMIT_WAL */
4332   return rc;
4333 }
4334 
4335 /*
4336 ** Open a read-transaction on the snapshot idendified by pSnapshot.
4337 */
4338 int sqlite3_snapshot_open(
4339   sqlite3 *db,
4340   const char *zDb,
4341   sqlite3_snapshot *pSnapshot
4342 ){
4343   int rc = SQLITE_ERROR;
4344 #ifndef SQLITE_OMIT_WAL
4345 
4346 #ifdef SQLITE_ENABLE_API_ARMOR
4347   if( !sqlite3SafetyCheckOk(db) ){
4348     return SQLITE_MISUSE_BKPT;
4349   }
4350 #endif
4351   sqlite3_mutex_enter(db->mutex);
4352   if( db->autoCommit==0 ){
4353     int iDb;
4354     iDb = sqlite3FindDbName(db, zDb);
4355     if( iDb==0 || iDb>1 ){
4356       Btree *pBt = db->aDb[iDb].pBt;
4357       if( sqlite3BtreeIsInTrans(pBt)==0 ){
4358         Pager *pPager = sqlite3BtreePager(pBt);
4359         int bUnlock = 0;
4360         if( sqlite3BtreeIsInReadTrans(pBt) ){
4361           if( db->nVdbeActive==0 ){
4362             rc = sqlite3PagerSnapshotCheck(pPager, pSnapshot);
4363             if( rc==SQLITE_OK ){
4364               bUnlock = 1;
4365               rc = sqlite3BtreeCommit(pBt);
4366             }
4367           }
4368         }else{
4369           rc = SQLITE_OK;
4370         }
4371         if( rc==SQLITE_OK ){
4372           rc = sqlite3PagerSnapshotOpen(pPager, pSnapshot);
4373         }
4374         if( rc==SQLITE_OK ){
4375           rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
4376           sqlite3PagerSnapshotOpen(pPager, 0);
4377         }
4378         if( bUnlock ){
4379           sqlite3PagerSnapshotUnlock(pPager);
4380         }
4381       }
4382     }
4383   }
4384 
4385   sqlite3_mutex_leave(db->mutex);
4386 #endif   /* SQLITE_OMIT_WAL */
4387   return rc;
4388 }
4389 
4390 /*
4391 ** Recover as many snapshots as possible from the wal file associated with
4392 ** schema zDb of database db.
4393 */
4394 int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb){
4395   int rc = SQLITE_ERROR;
4396   int iDb;
4397 #ifndef SQLITE_OMIT_WAL
4398 
4399 #ifdef SQLITE_ENABLE_API_ARMOR
4400   if( !sqlite3SafetyCheckOk(db) ){
4401     return SQLITE_MISUSE_BKPT;
4402   }
4403 #endif
4404 
4405   sqlite3_mutex_enter(db->mutex);
4406   iDb = sqlite3FindDbName(db, zDb);
4407   if( iDb==0 || iDb>1 ){
4408     Btree *pBt = db->aDb[iDb].pBt;
4409     if( 0==sqlite3BtreeIsInReadTrans(pBt) ){
4410       rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
4411       if( rc==SQLITE_OK ){
4412         rc = sqlite3PagerSnapshotRecover(sqlite3BtreePager(pBt));
4413         sqlite3BtreeCommit(pBt);
4414       }
4415     }
4416   }
4417   sqlite3_mutex_leave(db->mutex);
4418 #endif   /* SQLITE_OMIT_WAL */
4419   return rc;
4420 }
4421 
4422 /*
4423 ** Free a snapshot handle obtained from sqlite3_snapshot_get().
4424 */
4425 void sqlite3_snapshot_free(sqlite3_snapshot *pSnapshot){
4426   sqlite3_free(pSnapshot);
4427 }
4428 #endif /* SQLITE_ENABLE_SNAPSHOT */
4429 
4430 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
4431 /*
4432 ** Given the name of a compile-time option, return true if that option
4433 ** was used and false if not.
4434 **
4435 ** The name can optionally begin with "SQLITE_" but the "SQLITE_" prefix
4436 ** is not required for a match.
4437 */
4438 int sqlite3_compileoption_used(const char *zOptName){
4439   int i, n;
4440   int nOpt;
4441   const char **azCompileOpt;
4442 
4443 #if SQLITE_ENABLE_API_ARMOR
4444   if( zOptName==0 ){
4445     (void)SQLITE_MISUSE_BKPT;
4446     return 0;
4447   }
4448 #endif
4449 
4450   azCompileOpt = sqlite3CompileOptions(&nOpt);
4451 
4452   if( sqlite3StrNICmp(zOptName, "SQLITE_", 7)==0 ) zOptName += 7;
4453   n = sqlite3Strlen30(zOptName);
4454 
4455   /* Since nOpt is normally in single digits, a linear search is
4456   ** adequate. No need for a binary search. */
4457   for(i=0; i<nOpt; i++){
4458     if( sqlite3StrNICmp(zOptName, azCompileOpt[i], n)==0
4459      && sqlite3IsIdChar((unsigned char)azCompileOpt[i][n])==0
4460     ){
4461       return 1;
4462     }
4463   }
4464   return 0;
4465 }
4466 
4467 /*
4468 ** Return the N-th compile-time option string.  If N is out of range,
4469 ** return a NULL pointer.
4470 */
4471 const char *sqlite3_compileoption_get(int N){
4472   int nOpt;
4473   const char **azCompileOpt;
4474   azCompileOpt = sqlite3CompileOptions(&nOpt);
4475   if( N>=0 && N<nOpt ){
4476     return azCompileOpt[N];
4477   }
4478   return 0;
4479 }
4480 #endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
4481