xref: /sqlite-3.40.0/src/main.c (revision e99cb2da)
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_CANTOPEN_SYMLINK:   zName = "SQLITE_CANTOPEN_SYMLINK";  break;
1394       case SQLITE_PROTOCOL:           zName = "SQLITE_PROTOCOL";          break;
1395       case SQLITE_EMPTY:              zName = "SQLITE_EMPTY";             break;
1396       case SQLITE_SCHEMA:             zName = "SQLITE_SCHEMA";            break;
1397       case SQLITE_TOOBIG:             zName = "SQLITE_TOOBIG";            break;
1398       case SQLITE_CONSTRAINT:         zName = "SQLITE_CONSTRAINT";        break;
1399       case SQLITE_CONSTRAINT_UNIQUE:  zName = "SQLITE_CONSTRAINT_UNIQUE"; break;
1400       case SQLITE_CONSTRAINT_TRIGGER: zName = "SQLITE_CONSTRAINT_TRIGGER";break;
1401       case SQLITE_CONSTRAINT_FOREIGNKEY:
1402                                 zName = "SQLITE_CONSTRAINT_FOREIGNKEY";   break;
1403       case SQLITE_CONSTRAINT_CHECK:   zName = "SQLITE_CONSTRAINT_CHECK";  break;
1404       case SQLITE_CONSTRAINT_PRIMARYKEY:
1405                                 zName = "SQLITE_CONSTRAINT_PRIMARYKEY";   break;
1406       case SQLITE_CONSTRAINT_NOTNULL: zName = "SQLITE_CONSTRAINT_NOTNULL";break;
1407       case SQLITE_CONSTRAINT_COMMITHOOK:
1408                                 zName = "SQLITE_CONSTRAINT_COMMITHOOK";   break;
1409       case SQLITE_CONSTRAINT_VTAB:    zName = "SQLITE_CONSTRAINT_VTAB";   break;
1410       case SQLITE_CONSTRAINT_FUNCTION:
1411                                 zName = "SQLITE_CONSTRAINT_FUNCTION";     break;
1412       case SQLITE_CONSTRAINT_ROWID:   zName = "SQLITE_CONSTRAINT_ROWID";  break;
1413       case SQLITE_MISMATCH:           zName = "SQLITE_MISMATCH";          break;
1414       case SQLITE_MISUSE:             zName = "SQLITE_MISUSE";            break;
1415       case SQLITE_NOLFS:              zName = "SQLITE_NOLFS";             break;
1416       case SQLITE_AUTH:               zName = "SQLITE_AUTH";              break;
1417       case SQLITE_FORMAT:             zName = "SQLITE_FORMAT";            break;
1418       case SQLITE_RANGE:              zName = "SQLITE_RANGE";             break;
1419       case SQLITE_NOTADB:             zName = "SQLITE_NOTADB";            break;
1420       case SQLITE_ROW:                zName = "SQLITE_ROW";               break;
1421       case SQLITE_NOTICE:             zName = "SQLITE_NOTICE";            break;
1422       case SQLITE_NOTICE_RECOVER_WAL: zName = "SQLITE_NOTICE_RECOVER_WAL";break;
1423       case SQLITE_NOTICE_RECOVER_ROLLBACK:
1424                                 zName = "SQLITE_NOTICE_RECOVER_ROLLBACK"; break;
1425       case SQLITE_WARNING:            zName = "SQLITE_WARNING";           break;
1426       case SQLITE_WARNING_AUTOINDEX:  zName = "SQLITE_WARNING_AUTOINDEX"; break;
1427       case SQLITE_DONE:               zName = "SQLITE_DONE";              break;
1428     }
1429   }
1430   if( zName==0 ){
1431     static char zBuf[50];
1432     sqlite3_snprintf(sizeof(zBuf), zBuf, "SQLITE_UNKNOWN(%d)", origRc);
1433     zName = zBuf;
1434   }
1435   return zName;
1436 }
1437 #endif
1438 
1439 /*
1440 ** Return a static string that describes the kind of error specified in the
1441 ** argument.
1442 */
1443 const char *sqlite3ErrStr(int rc){
1444   static const char* const aMsg[] = {
1445     /* SQLITE_OK          */ "not an error",
1446     /* SQLITE_ERROR       */ "SQL logic error",
1447     /* SQLITE_INTERNAL    */ 0,
1448     /* SQLITE_PERM        */ "access permission denied",
1449     /* SQLITE_ABORT       */ "query aborted",
1450     /* SQLITE_BUSY        */ "database is locked",
1451     /* SQLITE_LOCKED      */ "database table is locked",
1452     /* SQLITE_NOMEM       */ "out of memory",
1453     /* SQLITE_READONLY    */ "attempt to write a readonly database",
1454     /* SQLITE_INTERRUPT   */ "interrupted",
1455     /* SQLITE_IOERR       */ "disk I/O error",
1456     /* SQLITE_CORRUPT     */ "database disk image is malformed",
1457     /* SQLITE_NOTFOUND    */ "unknown operation",
1458     /* SQLITE_FULL        */ "database or disk is full",
1459     /* SQLITE_CANTOPEN    */ "unable to open database file",
1460     /* SQLITE_PROTOCOL    */ "locking protocol",
1461     /* SQLITE_EMPTY       */ 0,
1462     /* SQLITE_SCHEMA      */ "database schema has changed",
1463     /* SQLITE_TOOBIG      */ "string or blob too big",
1464     /* SQLITE_CONSTRAINT  */ "constraint failed",
1465     /* SQLITE_MISMATCH    */ "datatype mismatch",
1466     /* SQLITE_MISUSE      */ "bad parameter or other API misuse",
1467 #ifdef SQLITE_DISABLE_LFS
1468     /* SQLITE_NOLFS       */ "large file support is disabled",
1469 #else
1470     /* SQLITE_NOLFS       */ 0,
1471 #endif
1472     /* SQLITE_AUTH        */ "authorization denied",
1473     /* SQLITE_FORMAT      */ 0,
1474     /* SQLITE_RANGE       */ "column index out of range",
1475     /* SQLITE_NOTADB      */ "file is not a database",
1476     /* SQLITE_NOTICE      */ "notification message",
1477     /* SQLITE_WARNING     */ "warning message",
1478   };
1479   const char *zErr = "unknown error";
1480   switch( rc ){
1481     case SQLITE_ABORT_ROLLBACK: {
1482       zErr = "abort due to ROLLBACK";
1483       break;
1484     }
1485     case SQLITE_ROW: {
1486       zErr = "another row available";
1487       break;
1488     }
1489     case SQLITE_DONE: {
1490       zErr = "no more rows available";
1491       break;
1492     }
1493     default: {
1494       rc &= 0xff;
1495       if( ALWAYS(rc>=0) && rc<ArraySize(aMsg) && aMsg[rc]!=0 ){
1496         zErr = aMsg[rc];
1497       }
1498       break;
1499     }
1500   }
1501   return zErr;
1502 }
1503 
1504 /*
1505 ** This routine implements a busy callback that sleeps and tries
1506 ** again until a timeout value is reached.  The timeout value is
1507 ** an integer number of milliseconds passed in as the first
1508 ** argument.
1509 **
1510 ** Return non-zero to retry the lock.  Return zero to stop trying
1511 ** and cause SQLite to return SQLITE_BUSY.
1512 */
1513 static int sqliteDefaultBusyCallback(
1514   void *ptr,               /* Database connection */
1515   int count,               /* Number of times table has been busy */
1516   sqlite3_file *pFile      /* The file on which the lock occurred */
1517 ){
1518 #if SQLITE_OS_WIN || HAVE_USLEEP
1519   /* This case is for systems that have support for sleeping for fractions of
1520   ** a second.  Examples:  All windows systems, unix systems with usleep() */
1521   static const u8 delays[] =
1522      { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
1523   static const u8 totals[] =
1524      { 0, 1, 3,  8, 18, 33, 53, 78, 103, 128, 178, 228 };
1525 # define NDELAY ArraySize(delays)
1526   sqlite3 *db = (sqlite3 *)ptr;
1527   int tmout = db->busyTimeout;
1528   int delay, prior;
1529 
1530 #ifdef SQLITE_ENABLE_SETLK_TIMEOUT
1531   if( sqlite3OsFileControl(pFile,SQLITE_FCNTL_LOCK_TIMEOUT,&tmout)==SQLITE_OK ){
1532     if( count ){
1533       tmout = 0;
1534       sqlite3OsFileControl(pFile, SQLITE_FCNTL_LOCK_TIMEOUT, &tmout);
1535       return 0;
1536     }else{
1537       return 1;
1538     }
1539   }
1540 #else
1541   UNUSED_PARAMETER(pFile);
1542 #endif
1543   assert( count>=0 );
1544   if( count < NDELAY ){
1545     delay = delays[count];
1546     prior = totals[count];
1547   }else{
1548     delay = delays[NDELAY-1];
1549     prior = totals[NDELAY-1] + delay*(count-(NDELAY-1));
1550   }
1551   if( prior + delay > tmout ){
1552     delay = tmout - prior;
1553     if( delay<=0 ) return 0;
1554   }
1555   sqlite3OsSleep(db->pVfs, delay*1000);
1556   return 1;
1557 #else
1558   /* This case for unix systems that lack usleep() support.  Sleeping
1559   ** must be done in increments of whole seconds */
1560   sqlite3 *db = (sqlite3 *)ptr;
1561   int tmout = ((sqlite3 *)ptr)->busyTimeout;
1562   UNUSED_PARAMETER(pFile);
1563   if( (count+1)*1000 > tmout ){
1564     return 0;
1565   }
1566   sqlite3OsSleep(db->pVfs, 1000000);
1567   return 1;
1568 #endif
1569 }
1570 
1571 /*
1572 ** Invoke the given busy handler.
1573 **
1574 ** This routine is called when an operation failed to acquire a
1575 ** lock on VFS file pFile.
1576 **
1577 ** If this routine returns non-zero, the lock is retried.  If it
1578 ** returns 0, the operation aborts with an SQLITE_BUSY error.
1579 */
1580 int sqlite3InvokeBusyHandler(BusyHandler *p, sqlite3_file *pFile){
1581   int rc;
1582   if( p->xBusyHandler==0 || p->nBusy<0 ) return 0;
1583   if( p->bExtraFileArg ){
1584     /* Add an extra parameter with the pFile pointer to the end of the
1585     ** callback argument list */
1586     int (*xTra)(void*,int,sqlite3_file*);
1587     xTra = (int(*)(void*,int,sqlite3_file*))p->xBusyHandler;
1588     rc = xTra(p->pBusyArg, p->nBusy, pFile);
1589   }else{
1590     /* Legacy style busy handler callback */
1591     rc = p->xBusyHandler(p->pBusyArg, p->nBusy);
1592   }
1593   if( rc==0 ){
1594     p->nBusy = -1;
1595   }else{
1596     p->nBusy++;
1597   }
1598   return rc;
1599 }
1600 
1601 /*
1602 ** This routine sets the busy callback for an Sqlite database to the
1603 ** given callback function with the given argument.
1604 */
1605 int sqlite3_busy_handler(
1606   sqlite3 *db,
1607   int (*xBusy)(void*,int),
1608   void *pArg
1609 ){
1610 #ifdef SQLITE_ENABLE_API_ARMOR
1611   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
1612 #endif
1613   sqlite3_mutex_enter(db->mutex);
1614   db->busyHandler.xBusyHandler = xBusy;
1615   db->busyHandler.pBusyArg = pArg;
1616   db->busyHandler.nBusy = 0;
1617   db->busyHandler.bExtraFileArg = 0;
1618   db->busyTimeout = 0;
1619   sqlite3_mutex_leave(db->mutex);
1620   return SQLITE_OK;
1621 }
1622 
1623 #ifndef SQLITE_OMIT_PROGRESS_CALLBACK
1624 /*
1625 ** This routine sets the progress callback for an Sqlite database to the
1626 ** given callback function with the given argument. The progress callback will
1627 ** be invoked every nOps opcodes.
1628 */
1629 void sqlite3_progress_handler(
1630   sqlite3 *db,
1631   int nOps,
1632   int (*xProgress)(void*),
1633   void *pArg
1634 ){
1635 #ifdef SQLITE_ENABLE_API_ARMOR
1636   if( !sqlite3SafetyCheckOk(db) ){
1637     (void)SQLITE_MISUSE_BKPT;
1638     return;
1639   }
1640 #endif
1641   sqlite3_mutex_enter(db->mutex);
1642   if( nOps>0 ){
1643     db->xProgress = xProgress;
1644     db->nProgressOps = (unsigned)nOps;
1645     db->pProgressArg = pArg;
1646   }else{
1647     db->xProgress = 0;
1648     db->nProgressOps = 0;
1649     db->pProgressArg = 0;
1650   }
1651   sqlite3_mutex_leave(db->mutex);
1652 }
1653 #endif
1654 
1655 
1656 /*
1657 ** This routine installs a default busy handler that waits for the
1658 ** specified number of milliseconds before returning 0.
1659 */
1660 int sqlite3_busy_timeout(sqlite3 *db, int ms){
1661 #ifdef SQLITE_ENABLE_API_ARMOR
1662   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
1663 #endif
1664   if( ms>0 ){
1665     sqlite3_busy_handler(db, (int(*)(void*,int))sqliteDefaultBusyCallback,
1666                              (void*)db);
1667     db->busyTimeout = ms;
1668     db->busyHandler.bExtraFileArg = 1;
1669   }else{
1670     sqlite3_busy_handler(db, 0, 0);
1671   }
1672   return SQLITE_OK;
1673 }
1674 
1675 /*
1676 ** Cause any pending operation to stop at its earliest opportunity.
1677 */
1678 void sqlite3_interrupt(sqlite3 *db){
1679 #ifdef SQLITE_ENABLE_API_ARMOR
1680   if( !sqlite3SafetyCheckOk(db) && (db==0 || db->magic!=SQLITE_MAGIC_ZOMBIE) ){
1681     (void)SQLITE_MISUSE_BKPT;
1682     return;
1683   }
1684 #endif
1685   db->u1.isInterrupted = 1;
1686 }
1687 
1688 
1689 /*
1690 ** This function is exactly the same as sqlite3_create_function(), except
1691 ** that it is designed to be called by internal code. The difference is
1692 ** that if a malloc() fails in sqlite3_create_function(), an error code
1693 ** is returned and the mallocFailed flag cleared.
1694 */
1695 int sqlite3CreateFunc(
1696   sqlite3 *db,
1697   const char *zFunctionName,
1698   int nArg,
1699   int enc,
1700   void *pUserData,
1701   void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
1702   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1703   void (*xFinal)(sqlite3_context*),
1704   void (*xValue)(sqlite3_context*),
1705   void (*xInverse)(sqlite3_context*,int,sqlite3_value **),
1706   FuncDestructor *pDestructor
1707 ){
1708   FuncDef *p;
1709   int nName;
1710   int extraFlags;
1711 
1712   assert( sqlite3_mutex_held(db->mutex) );
1713   assert( xValue==0 || xSFunc==0 );
1714   if( zFunctionName==0                /* Must have a valid name */
1715    || (xSFunc!=0 && xFinal!=0)        /* Not both xSFunc and xFinal */
1716    || ((xFinal==0)!=(xStep==0))       /* Both or neither of xFinal and xStep */
1717    || ((xValue==0)!=(xInverse==0))    /* Both or neither of xValue, xInverse */
1718    || (nArg<-1 || nArg>SQLITE_MAX_FUNCTION_ARG)
1719    || (255<(nName = sqlite3Strlen30( zFunctionName)))
1720   ){
1721     return SQLITE_MISUSE_BKPT;
1722   }
1723 
1724   assert( SQLITE_FUNC_CONSTANT==SQLITE_DETERMINISTIC );
1725   assert( SQLITE_FUNC_DIRECT==SQLITE_DIRECTONLY );
1726   extraFlags = enc &  (SQLITE_DETERMINISTIC|SQLITE_DIRECTONLY|SQLITE_SUBTYPE);
1727   enc &= (SQLITE_FUNC_ENCMASK|SQLITE_ANY);
1728 
1729 #ifndef SQLITE_OMIT_UTF16
1730   /* If SQLITE_UTF16 is specified as the encoding type, transform this
1731   ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
1732   ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
1733   **
1734   ** If SQLITE_ANY is specified, add three versions of the function
1735   ** to the hash table.
1736   */
1737   if( enc==SQLITE_UTF16 ){
1738     enc = SQLITE_UTF16NATIVE;
1739   }else if( enc==SQLITE_ANY ){
1740     int rc;
1741     rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF8|extraFlags,
1742          pUserData, xSFunc, xStep, xFinal, xValue, xInverse, pDestructor);
1743     if( rc==SQLITE_OK ){
1744       rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF16LE|extraFlags,
1745           pUserData, xSFunc, xStep, xFinal, xValue, xInverse, pDestructor);
1746     }
1747     if( rc!=SQLITE_OK ){
1748       return rc;
1749     }
1750     enc = SQLITE_UTF16BE;
1751   }
1752 #else
1753   enc = SQLITE_UTF8;
1754 #endif
1755 
1756   /* Check if an existing function is being overridden or deleted. If so,
1757   ** and there are active VMs, then return SQLITE_BUSY. If a function
1758   ** is being overridden/deleted but there are no active VMs, allow the
1759   ** operation to continue but invalidate all precompiled statements.
1760   */
1761   p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 0);
1762   if( p && (p->funcFlags & SQLITE_FUNC_ENCMASK)==(u32)enc && p->nArg==nArg ){
1763     if( db->nVdbeActive ){
1764       sqlite3ErrorWithMsg(db, SQLITE_BUSY,
1765         "unable to delete/modify user-function due to active statements");
1766       assert( !db->mallocFailed );
1767       return SQLITE_BUSY;
1768     }else{
1769       sqlite3ExpirePreparedStatements(db, 0);
1770     }
1771   }
1772 
1773   p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 1);
1774   assert(p || db->mallocFailed);
1775   if( !p ){
1776     return SQLITE_NOMEM_BKPT;
1777   }
1778 
1779   /* If an older version of the function with a configured destructor is
1780   ** being replaced invoke the destructor function here. */
1781   functionDestroy(db, p);
1782 
1783   if( pDestructor ){
1784     pDestructor->nRef++;
1785   }
1786   p->u.pDestructor = pDestructor;
1787   p->funcFlags = (p->funcFlags & SQLITE_FUNC_ENCMASK) | extraFlags;
1788   testcase( p->funcFlags & SQLITE_DETERMINISTIC );
1789   testcase( p->funcFlags & SQLITE_DIRECTONLY );
1790   p->xSFunc = xSFunc ? xSFunc : xStep;
1791   p->xFinalize = xFinal;
1792   p->xValue = xValue;
1793   p->xInverse = xInverse;
1794   p->pUserData = pUserData;
1795   p->nArg = (u16)nArg;
1796   return SQLITE_OK;
1797 }
1798 
1799 /*
1800 ** Worker function used by utf-8 APIs that create new functions:
1801 **
1802 **    sqlite3_create_function()
1803 **    sqlite3_create_function_v2()
1804 **    sqlite3_create_window_function()
1805 */
1806 static int createFunctionApi(
1807   sqlite3 *db,
1808   const char *zFunc,
1809   int nArg,
1810   int enc,
1811   void *p,
1812   void (*xSFunc)(sqlite3_context*,int,sqlite3_value**),
1813   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
1814   void (*xFinal)(sqlite3_context*),
1815   void (*xValue)(sqlite3_context*),
1816   void (*xInverse)(sqlite3_context*,int,sqlite3_value**),
1817   void(*xDestroy)(void*)
1818 ){
1819   int rc = SQLITE_ERROR;
1820   FuncDestructor *pArg = 0;
1821 
1822 #ifdef SQLITE_ENABLE_API_ARMOR
1823   if( !sqlite3SafetyCheckOk(db) ){
1824     return SQLITE_MISUSE_BKPT;
1825   }
1826 #endif
1827   sqlite3_mutex_enter(db->mutex);
1828   if( xDestroy ){
1829     pArg = (FuncDestructor *)sqlite3Malloc(sizeof(FuncDestructor));
1830     if( !pArg ){
1831       sqlite3OomFault(db);
1832       xDestroy(p);
1833       goto out;
1834     }
1835     pArg->nRef = 0;
1836     pArg->xDestroy = xDestroy;
1837     pArg->pUserData = p;
1838   }
1839   rc = sqlite3CreateFunc(db, zFunc, nArg, enc, p,
1840       xSFunc, xStep, xFinal, xValue, xInverse, pArg
1841   );
1842   if( pArg && pArg->nRef==0 ){
1843     assert( rc!=SQLITE_OK );
1844     xDestroy(p);
1845     sqlite3_free(pArg);
1846   }
1847 
1848  out:
1849   rc = sqlite3ApiExit(db, rc);
1850   sqlite3_mutex_leave(db->mutex);
1851   return rc;
1852 }
1853 
1854 /*
1855 ** Create new user functions.
1856 */
1857 int sqlite3_create_function(
1858   sqlite3 *db,
1859   const char *zFunc,
1860   int nArg,
1861   int enc,
1862   void *p,
1863   void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
1864   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1865   void (*xFinal)(sqlite3_context*)
1866 ){
1867   return createFunctionApi(db, zFunc, nArg, enc, p, xSFunc, xStep,
1868                                     xFinal, 0, 0, 0);
1869 }
1870 int sqlite3_create_function_v2(
1871   sqlite3 *db,
1872   const char *zFunc,
1873   int nArg,
1874   int enc,
1875   void *p,
1876   void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
1877   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1878   void (*xFinal)(sqlite3_context*),
1879   void (*xDestroy)(void *)
1880 ){
1881   return createFunctionApi(db, zFunc, nArg, enc, p, xSFunc, xStep,
1882                                     xFinal, 0, 0, xDestroy);
1883 }
1884 int sqlite3_create_window_function(
1885   sqlite3 *db,
1886   const char *zFunc,
1887   int nArg,
1888   int enc,
1889   void *p,
1890   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1891   void (*xFinal)(sqlite3_context*),
1892   void (*xValue)(sqlite3_context*),
1893   void (*xInverse)(sqlite3_context*,int,sqlite3_value **),
1894   void (*xDestroy)(void *)
1895 ){
1896   return createFunctionApi(db, zFunc, nArg, enc, p, 0, xStep,
1897                                     xFinal, xValue, xInverse, xDestroy);
1898 }
1899 
1900 #ifndef SQLITE_OMIT_UTF16
1901 int sqlite3_create_function16(
1902   sqlite3 *db,
1903   const void *zFunctionName,
1904   int nArg,
1905   int eTextRep,
1906   void *p,
1907   void (*xSFunc)(sqlite3_context*,int,sqlite3_value**),
1908   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
1909   void (*xFinal)(sqlite3_context*)
1910 ){
1911   int rc;
1912   char *zFunc8;
1913 
1914 #ifdef SQLITE_ENABLE_API_ARMOR
1915   if( !sqlite3SafetyCheckOk(db) || zFunctionName==0 ) return SQLITE_MISUSE_BKPT;
1916 #endif
1917   sqlite3_mutex_enter(db->mutex);
1918   assert( !db->mallocFailed );
1919   zFunc8 = sqlite3Utf16to8(db, zFunctionName, -1, SQLITE_UTF16NATIVE);
1920   rc = sqlite3CreateFunc(db, zFunc8, nArg, eTextRep, p, xSFunc,xStep,xFinal,0,0,0);
1921   sqlite3DbFree(db, zFunc8);
1922   rc = sqlite3ApiExit(db, rc);
1923   sqlite3_mutex_leave(db->mutex);
1924   return rc;
1925 }
1926 #endif
1927 
1928 
1929 /*
1930 ** The following is the implementation of an SQL function that always
1931 ** fails with an error message stating that the function is used in the
1932 ** wrong context.  The sqlite3_overload_function() API might construct
1933 ** SQL function that use this routine so that the functions will exist
1934 ** for name resolution but are actually overloaded by the xFindFunction
1935 ** method of virtual tables.
1936 */
1937 static void sqlite3InvalidFunction(
1938   sqlite3_context *context,  /* The function calling context */
1939   int NotUsed,               /* Number of arguments to the function */
1940   sqlite3_value **NotUsed2   /* Value of each argument */
1941 ){
1942   const char *zName = (const char*)sqlite3_user_data(context);
1943   char *zErr;
1944   UNUSED_PARAMETER2(NotUsed, NotUsed2);
1945   zErr = sqlite3_mprintf(
1946       "unable to use function %s in the requested context", zName);
1947   sqlite3_result_error(context, zErr, -1);
1948   sqlite3_free(zErr);
1949 }
1950 
1951 /*
1952 ** Declare that a function has been overloaded by a virtual table.
1953 **
1954 ** If the function already exists as a regular global function, then
1955 ** this routine is a no-op.  If the function does not exist, then create
1956 ** a new one that always throws a run-time error.
1957 **
1958 ** When virtual tables intend to provide an overloaded function, they
1959 ** should call this routine to make sure the global function exists.
1960 ** A global function must exist in order for name resolution to work
1961 ** properly.
1962 */
1963 int sqlite3_overload_function(
1964   sqlite3 *db,
1965   const char *zName,
1966   int nArg
1967 ){
1968   int rc;
1969   char *zCopy;
1970 
1971 #ifdef SQLITE_ENABLE_API_ARMOR
1972   if( !sqlite3SafetyCheckOk(db) || zName==0 || nArg<-2 ){
1973     return SQLITE_MISUSE_BKPT;
1974   }
1975 #endif
1976   sqlite3_mutex_enter(db->mutex);
1977   rc = sqlite3FindFunction(db, zName, nArg, SQLITE_UTF8, 0)!=0;
1978   sqlite3_mutex_leave(db->mutex);
1979   if( rc ) return SQLITE_OK;
1980   zCopy = sqlite3_mprintf(zName);
1981   if( zCopy==0 ) return SQLITE_NOMEM;
1982   return sqlite3_create_function_v2(db, zName, nArg, SQLITE_UTF8,
1983                            zCopy, sqlite3InvalidFunction, 0, 0, sqlite3_free);
1984 }
1985 
1986 #ifndef SQLITE_OMIT_TRACE
1987 /*
1988 ** Register a trace function.  The pArg from the previously registered trace
1989 ** is returned.
1990 **
1991 ** A NULL trace function means that no tracing is executes.  A non-NULL
1992 ** trace is a pointer to a function that is invoked at the start of each
1993 ** SQL statement.
1994 */
1995 #ifndef SQLITE_OMIT_DEPRECATED
1996 void *sqlite3_trace(sqlite3 *db, void(*xTrace)(void*,const char*), void *pArg){
1997   void *pOld;
1998 
1999 #ifdef SQLITE_ENABLE_API_ARMOR
2000   if( !sqlite3SafetyCheckOk(db) ){
2001     (void)SQLITE_MISUSE_BKPT;
2002     return 0;
2003   }
2004 #endif
2005   sqlite3_mutex_enter(db->mutex);
2006   pOld = db->pTraceArg;
2007   db->mTrace = xTrace ? SQLITE_TRACE_LEGACY : 0;
2008   db->xTrace = (int(*)(u32,void*,void*,void*))xTrace;
2009   db->pTraceArg = pArg;
2010   sqlite3_mutex_leave(db->mutex);
2011   return pOld;
2012 }
2013 #endif /* SQLITE_OMIT_DEPRECATED */
2014 
2015 /* Register a trace callback using the version-2 interface.
2016 */
2017 int sqlite3_trace_v2(
2018   sqlite3 *db,                               /* Trace this connection */
2019   unsigned mTrace,                           /* Mask of events to be traced */
2020   int(*xTrace)(unsigned,void*,void*,void*),  /* Callback to invoke */
2021   void *pArg                                 /* Context */
2022 ){
2023 #ifdef SQLITE_ENABLE_API_ARMOR
2024   if( !sqlite3SafetyCheckOk(db) ){
2025     return SQLITE_MISUSE_BKPT;
2026   }
2027 #endif
2028   sqlite3_mutex_enter(db->mutex);
2029   if( mTrace==0 ) xTrace = 0;
2030   if( xTrace==0 ) mTrace = 0;
2031   db->mTrace = mTrace;
2032   db->xTrace = xTrace;
2033   db->pTraceArg = pArg;
2034   sqlite3_mutex_leave(db->mutex);
2035   return SQLITE_OK;
2036 }
2037 
2038 #ifndef SQLITE_OMIT_DEPRECATED
2039 /*
2040 ** Register a profile function.  The pArg from the previously registered
2041 ** profile function is returned.
2042 **
2043 ** A NULL profile function means that no profiling is executes.  A non-NULL
2044 ** profile is a pointer to a function that is invoked at the conclusion of
2045 ** each SQL statement that is run.
2046 */
2047 void *sqlite3_profile(
2048   sqlite3 *db,
2049   void (*xProfile)(void*,const char*,sqlite_uint64),
2050   void *pArg
2051 ){
2052   void *pOld;
2053 
2054 #ifdef SQLITE_ENABLE_API_ARMOR
2055   if( !sqlite3SafetyCheckOk(db) ){
2056     (void)SQLITE_MISUSE_BKPT;
2057     return 0;
2058   }
2059 #endif
2060   sqlite3_mutex_enter(db->mutex);
2061   pOld = db->pProfileArg;
2062   db->xProfile = xProfile;
2063   db->pProfileArg = pArg;
2064   db->mTrace &= SQLITE_TRACE_NONLEGACY_MASK;
2065   if( db->xProfile ) db->mTrace |= SQLITE_TRACE_XPROFILE;
2066   sqlite3_mutex_leave(db->mutex);
2067   return pOld;
2068 }
2069 #endif /* SQLITE_OMIT_DEPRECATED */
2070 #endif /* SQLITE_OMIT_TRACE */
2071 
2072 /*
2073 ** Register a function to be invoked when a transaction commits.
2074 ** If the invoked function returns non-zero, then the commit becomes a
2075 ** rollback.
2076 */
2077 void *sqlite3_commit_hook(
2078   sqlite3 *db,              /* Attach the hook to this database */
2079   int (*xCallback)(void*),  /* Function to invoke on each commit */
2080   void *pArg                /* Argument to the function */
2081 ){
2082   void *pOld;
2083 
2084 #ifdef SQLITE_ENABLE_API_ARMOR
2085   if( !sqlite3SafetyCheckOk(db) ){
2086     (void)SQLITE_MISUSE_BKPT;
2087     return 0;
2088   }
2089 #endif
2090   sqlite3_mutex_enter(db->mutex);
2091   pOld = db->pCommitArg;
2092   db->xCommitCallback = xCallback;
2093   db->pCommitArg = pArg;
2094   sqlite3_mutex_leave(db->mutex);
2095   return pOld;
2096 }
2097 
2098 /*
2099 ** Register a callback to be invoked each time a row is updated,
2100 ** inserted or deleted using this database connection.
2101 */
2102 void *sqlite3_update_hook(
2103   sqlite3 *db,              /* Attach the hook to this database */
2104   void (*xCallback)(void*,int,char const *,char const *,sqlite_int64),
2105   void *pArg                /* Argument to the function */
2106 ){
2107   void *pRet;
2108 
2109 #ifdef SQLITE_ENABLE_API_ARMOR
2110   if( !sqlite3SafetyCheckOk(db) ){
2111     (void)SQLITE_MISUSE_BKPT;
2112     return 0;
2113   }
2114 #endif
2115   sqlite3_mutex_enter(db->mutex);
2116   pRet = db->pUpdateArg;
2117   db->xUpdateCallback = xCallback;
2118   db->pUpdateArg = pArg;
2119   sqlite3_mutex_leave(db->mutex);
2120   return pRet;
2121 }
2122 
2123 /*
2124 ** Register a callback to be invoked each time a transaction is rolled
2125 ** back by this database connection.
2126 */
2127 void *sqlite3_rollback_hook(
2128   sqlite3 *db,              /* Attach the hook to this database */
2129   void (*xCallback)(void*), /* Callback function */
2130   void *pArg                /* Argument to the function */
2131 ){
2132   void *pRet;
2133 
2134 #ifdef SQLITE_ENABLE_API_ARMOR
2135   if( !sqlite3SafetyCheckOk(db) ){
2136     (void)SQLITE_MISUSE_BKPT;
2137     return 0;
2138   }
2139 #endif
2140   sqlite3_mutex_enter(db->mutex);
2141   pRet = db->pRollbackArg;
2142   db->xRollbackCallback = xCallback;
2143   db->pRollbackArg = pArg;
2144   sqlite3_mutex_leave(db->mutex);
2145   return pRet;
2146 }
2147 
2148 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
2149 /*
2150 ** Register a callback to be invoked each time a row is updated,
2151 ** inserted or deleted using this database connection.
2152 */
2153 void *sqlite3_preupdate_hook(
2154   sqlite3 *db,              /* Attach the hook to this database */
2155   void(*xCallback)(         /* Callback function */
2156     void*,sqlite3*,int,char const*,char const*,sqlite3_int64,sqlite3_int64),
2157   void *pArg                /* First callback argument */
2158 ){
2159   void *pRet;
2160   sqlite3_mutex_enter(db->mutex);
2161   pRet = db->pPreUpdateArg;
2162   db->xPreUpdateCallback = xCallback;
2163   db->pPreUpdateArg = pArg;
2164   sqlite3_mutex_leave(db->mutex);
2165   return pRet;
2166 }
2167 #endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
2168 
2169 #ifndef SQLITE_OMIT_WAL
2170 /*
2171 ** The sqlite3_wal_hook() callback registered by sqlite3_wal_autocheckpoint().
2172 ** Invoke sqlite3_wal_checkpoint if the number of frames in the log file
2173 ** is greater than sqlite3.pWalArg cast to an integer (the value configured by
2174 ** wal_autocheckpoint()).
2175 */
2176 int sqlite3WalDefaultHook(
2177   void *pClientData,     /* Argument */
2178   sqlite3 *db,           /* Connection */
2179   const char *zDb,       /* Database */
2180   int nFrame             /* Size of WAL */
2181 ){
2182   if( nFrame>=SQLITE_PTR_TO_INT(pClientData) ){
2183     sqlite3BeginBenignMalloc();
2184     sqlite3_wal_checkpoint(db, zDb);
2185     sqlite3EndBenignMalloc();
2186   }
2187   return SQLITE_OK;
2188 }
2189 #endif /* SQLITE_OMIT_WAL */
2190 
2191 /*
2192 ** Configure an sqlite3_wal_hook() callback to automatically checkpoint
2193 ** a database after committing a transaction if there are nFrame or
2194 ** more frames in the log file. Passing zero or a negative value as the
2195 ** nFrame parameter disables automatic checkpoints entirely.
2196 **
2197 ** The callback registered by this function replaces any existing callback
2198 ** registered using sqlite3_wal_hook(). Likewise, registering a callback
2199 ** using sqlite3_wal_hook() disables the automatic checkpoint mechanism
2200 ** configured by this function.
2201 */
2202 int sqlite3_wal_autocheckpoint(sqlite3 *db, int nFrame){
2203 #ifdef SQLITE_OMIT_WAL
2204   UNUSED_PARAMETER(db);
2205   UNUSED_PARAMETER(nFrame);
2206 #else
2207 #ifdef SQLITE_ENABLE_API_ARMOR
2208   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
2209 #endif
2210   if( nFrame>0 ){
2211     sqlite3_wal_hook(db, sqlite3WalDefaultHook, SQLITE_INT_TO_PTR(nFrame));
2212   }else{
2213     sqlite3_wal_hook(db, 0, 0);
2214   }
2215 #endif
2216   return SQLITE_OK;
2217 }
2218 
2219 /*
2220 ** Register a callback to be invoked each time a transaction is written
2221 ** into the write-ahead-log by this database connection.
2222 */
2223 void *sqlite3_wal_hook(
2224   sqlite3 *db,                    /* Attach the hook to this db handle */
2225   int(*xCallback)(void *, sqlite3*, const char*, int),
2226   void *pArg                      /* First argument passed to xCallback() */
2227 ){
2228 #ifndef SQLITE_OMIT_WAL
2229   void *pRet;
2230 #ifdef SQLITE_ENABLE_API_ARMOR
2231   if( !sqlite3SafetyCheckOk(db) ){
2232     (void)SQLITE_MISUSE_BKPT;
2233     return 0;
2234   }
2235 #endif
2236   sqlite3_mutex_enter(db->mutex);
2237   pRet = db->pWalArg;
2238   db->xWalCallback = xCallback;
2239   db->pWalArg = pArg;
2240   sqlite3_mutex_leave(db->mutex);
2241   return pRet;
2242 #else
2243   return 0;
2244 #endif
2245 }
2246 
2247 /*
2248 ** Checkpoint database zDb.
2249 */
2250 int sqlite3_wal_checkpoint_v2(
2251   sqlite3 *db,                    /* Database handle */
2252   const char *zDb,                /* Name of attached database (or NULL) */
2253   int eMode,                      /* SQLITE_CHECKPOINT_* value */
2254   int *pnLog,                     /* OUT: Size of WAL log in frames */
2255   int *pnCkpt                     /* OUT: Total number of frames checkpointed */
2256 ){
2257 #ifdef SQLITE_OMIT_WAL
2258   return SQLITE_OK;
2259 #else
2260   int rc;                         /* Return code */
2261   int iDb = SQLITE_MAX_ATTACHED;  /* sqlite3.aDb[] index of db to checkpoint */
2262 
2263 #ifdef SQLITE_ENABLE_API_ARMOR
2264   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
2265 #endif
2266 
2267   /* Initialize the output variables to -1 in case an error occurs. */
2268   if( pnLog ) *pnLog = -1;
2269   if( pnCkpt ) *pnCkpt = -1;
2270 
2271   assert( SQLITE_CHECKPOINT_PASSIVE==0 );
2272   assert( SQLITE_CHECKPOINT_FULL==1 );
2273   assert( SQLITE_CHECKPOINT_RESTART==2 );
2274   assert( SQLITE_CHECKPOINT_TRUNCATE==3 );
2275   if( eMode<SQLITE_CHECKPOINT_PASSIVE || eMode>SQLITE_CHECKPOINT_TRUNCATE ){
2276     /* EVIDENCE-OF: R-03996-12088 The M parameter must be a valid checkpoint
2277     ** mode: */
2278     return SQLITE_MISUSE;
2279   }
2280 
2281   sqlite3_mutex_enter(db->mutex);
2282   if( zDb && zDb[0] ){
2283     iDb = sqlite3FindDbName(db, zDb);
2284   }
2285   if( iDb<0 ){
2286     rc = SQLITE_ERROR;
2287     sqlite3ErrorWithMsg(db, SQLITE_ERROR, "unknown database: %s", zDb);
2288   }else{
2289     db->busyHandler.nBusy = 0;
2290     rc = sqlite3Checkpoint(db, iDb, eMode, pnLog, pnCkpt);
2291     sqlite3Error(db, rc);
2292   }
2293   rc = sqlite3ApiExit(db, rc);
2294 
2295   /* If there are no active statements, clear the interrupt flag at this
2296   ** point.  */
2297   if( db->nVdbeActive==0 ){
2298     db->u1.isInterrupted = 0;
2299   }
2300 
2301   sqlite3_mutex_leave(db->mutex);
2302   return rc;
2303 #endif
2304 }
2305 
2306 
2307 /*
2308 ** Checkpoint database zDb. If zDb is NULL, or if the buffer zDb points
2309 ** to contains a zero-length string, all attached databases are
2310 ** checkpointed.
2311 */
2312 int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb){
2313   /* EVIDENCE-OF: R-41613-20553 The sqlite3_wal_checkpoint(D,X) is equivalent to
2314   ** sqlite3_wal_checkpoint_v2(D,X,SQLITE_CHECKPOINT_PASSIVE,0,0). */
2315   return sqlite3_wal_checkpoint_v2(db,zDb,SQLITE_CHECKPOINT_PASSIVE,0,0);
2316 }
2317 
2318 #ifndef SQLITE_OMIT_WAL
2319 /*
2320 ** Run a checkpoint on database iDb. This is a no-op if database iDb is
2321 ** not currently open in WAL mode.
2322 **
2323 ** If a transaction is open on the database being checkpointed, this
2324 ** function returns SQLITE_LOCKED and a checkpoint is not attempted. If
2325 ** an error occurs while running the checkpoint, an SQLite error code is
2326 ** returned (i.e. SQLITE_IOERR). Otherwise, SQLITE_OK.
2327 **
2328 ** The mutex on database handle db should be held by the caller. The mutex
2329 ** associated with the specific b-tree being checkpointed is taken by
2330 ** this function while the checkpoint is running.
2331 **
2332 ** If iDb is passed SQLITE_MAX_ATTACHED, then all attached databases are
2333 ** checkpointed. If an error is encountered it is returned immediately -
2334 ** no attempt is made to checkpoint any remaining databases.
2335 **
2336 ** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL, RESTART
2337 ** or TRUNCATE.
2338 */
2339 int sqlite3Checkpoint(sqlite3 *db, int iDb, int eMode, int *pnLog, int *pnCkpt){
2340   int rc = SQLITE_OK;             /* Return code */
2341   int i;                          /* Used to iterate through attached dbs */
2342   int bBusy = 0;                  /* True if SQLITE_BUSY has been encountered */
2343 
2344   assert( sqlite3_mutex_held(db->mutex) );
2345   assert( !pnLog || *pnLog==-1 );
2346   assert( !pnCkpt || *pnCkpt==-1 );
2347 
2348   for(i=0; i<db->nDb && rc==SQLITE_OK; i++){
2349     if( i==iDb || iDb==SQLITE_MAX_ATTACHED ){
2350       rc = sqlite3BtreeCheckpoint(db->aDb[i].pBt, eMode, pnLog, pnCkpt);
2351       pnLog = 0;
2352       pnCkpt = 0;
2353       if( rc==SQLITE_BUSY ){
2354         bBusy = 1;
2355         rc = SQLITE_OK;
2356       }
2357     }
2358   }
2359 
2360   return (rc==SQLITE_OK && bBusy) ? SQLITE_BUSY : rc;
2361 }
2362 #endif /* SQLITE_OMIT_WAL */
2363 
2364 /*
2365 ** This function returns true if main-memory should be used instead of
2366 ** a temporary file for transient pager files and statement journals.
2367 ** The value returned depends on the value of db->temp_store (runtime
2368 ** parameter) and the compile time value of SQLITE_TEMP_STORE. The
2369 ** following table describes the relationship between these two values
2370 ** and this functions return value.
2371 **
2372 **   SQLITE_TEMP_STORE     db->temp_store     Location of temporary database
2373 **   -----------------     --------------     ------------------------------
2374 **   0                     any                file      (return 0)
2375 **   1                     1                  file      (return 0)
2376 **   1                     2                  memory    (return 1)
2377 **   1                     0                  file      (return 0)
2378 **   2                     1                  file      (return 0)
2379 **   2                     2                  memory    (return 1)
2380 **   2                     0                  memory    (return 1)
2381 **   3                     any                memory    (return 1)
2382 */
2383 int sqlite3TempInMemory(const sqlite3 *db){
2384 #if SQLITE_TEMP_STORE==1
2385   return ( db->temp_store==2 );
2386 #endif
2387 #if SQLITE_TEMP_STORE==2
2388   return ( db->temp_store!=1 );
2389 #endif
2390 #if SQLITE_TEMP_STORE==3
2391   UNUSED_PARAMETER(db);
2392   return 1;
2393 #endif
2394 #if SQLITE_TEMP_STORE<1 || SQLITE_TEMP_STORE>3
2395   UNUSED_PARAMETER(db);
2396   return 0;
2397 #endif
2398 }
2399 
2400 /*
2401 ** Return UTF-8 encoded English language explanation of the most recent
2402 ** error.
2403 */
2404 const char *sqlite3_errmsg(sqlite3 *db){
2405   const char *z;
2406   if( !db ){
2407     return sqlite3ErrStr(SQLITE_NOMEM_BKPT);
2408   }
2409   if( !sqlite3SafetyCheckSickOrOk(db) ){
2410     return sqlite3ErrStr(SQLITE_MISUSE_BKPT);
2411   }
2412   sqlite3_mutex_enter(db->mutex);
2413   if( db->mallocFailed ){
2414     z = sqlite3ErrStr(SQLITE_NOMEM_BKPT);
2415   }else{
2416     testcase( db->pErr==0 );
2417     z = db->errCode ? (char*)sqlite3_value_text(db->pErr) : 0;
2418     assert( !db->mallocFailed );
2419     if( z==0 ){
2420       z = sqlite3ErrStr(db->errCode);
2421     }
2422   }
2423   sqlite3_mutex_leave(db->mutex);
2424   return z;
2425 }
2426 
2427 #ifndef SQLITE_OMIT_UTF16
2428 /*
2429 ** Return UTF-16 encoded English language explanation of the most recent
2430 ** error.
2431 */
2432 const void *sqlite3_errmsg16(sqlite3 *db){
2433   static const u16 outOfMem[] = {
2434     'o', 'u', 't', ' ', 'o', 'f', ' ', 'm', 'e', 'm', 'o', 'r', 'y', 0
2435   };
2436   static const u16 misuse[] = {
2437     'b', 'a', 'd', ' ', 'p', 'a', 'r', 'a', 'm', 'e', 't', 'e', 'r', ' ',
2438     'o', 'r', ' ', 'o', 't', 'h', 'e', 'r', ' ', 'A', 'P', 'I', ' ',
2439     'm', 'i', 's', 'u', 's', 'e', 0
2440   };
2441 
2442   const void *z;
2443   if( !db ){
2444     return (void *)outOfMem;
2445   }
2446   if( !sqlite3SafetyCheckSickOrOk(db) ){
2447     return (void *)misuse;
2448   }
2449   sqlite3_mutex_enter(db->mutex);
2450   if( db->mallocFailed ){
2451     z = (void *)outOfMem;
2452   }else{
2453     z = sqlite3_value_text16(db->pErr);
2454     if( z==0 ){
2455       sqlite3ErrorWithMsg(db, db->errCode, sqlite3ErrStr(db->errCode));
2456       z = sqlite3_value_text16(db->pErr);
2457     }
2458     /* A malloc() may have failed within the call to sqlite3_value_text16()
2459     ** above. If this is the case, then the db->mallocFailed flag needs to
2460     ** be cleared before returning. Do this directly, instead of via
2461     ** sqlite3ApiExit(), to avoid setting the database handle error message.
2462     */
2463     sqlite3OomClear(db);
2464   }
2465   sqlite3_mutex_leave(db->mutex);
2466   return z;
2467 }
2468 #endif /* SQLITE_OMIT_UTF16 */
2469 
2470 /*
2471 ** Return the most recent error code generated by an SQLite routine. If NULL is
2472 ** passed to this function, we assume a malloc() failed during sqlite3_open().
2473 */
2474 int sqlite3_errcode(sqlite3 *db){
2475   if( db && !sqlite3SafetyCheckSickOrOk(db) ){
2476     return SQLITE_MISUSE_BKPT;
2477   }
2478   if( !db || db->mallocFailed ){
2479     return SQLITE_NOMEM_BKPT;
2480   }
2481   return db->errCode & db->errMask;
2482 }
2483 int sqlite3_extended_errcode(sqlite3 *db){
2484   if( db && !sqlite3SafetyCheckSickOrOk(db) ){
2485     return SQLITE_MISUSE_BKPT;
2486   }
2487   if( !db || db->mallocFailed ){
2488     return SQLITE_NOMEM_BKPT;
2489   }
2490   return db->errCode;
2491 }
2492 int sqlite3_system_errno(sqlite3 *db){
2493   return db ? db->iSysErrno : 0;
2494 }
2495 
2496 /*
2497 ** Return a string that describes the kind of error specified in the
2498 ** argument.  For now, this simply calls the internal sqlite3ErrStr()
2499 ** function.
2500 */
2501 const char *sqlite3_errstr(int rc){
2502   return sqlite3ErrStr(rc);
2503 }
2504 
2505 /*
2506 ** Create a new collating function for database "db".  The name is zName
2507 ** and the encoding is enc.
2508 */
2509 static int createCollation(
2510   sqlite3* db,
2511   const char *zName,
2512   u8 enc,
2513   void* pCtx,
2514   int(*xCompare)(void*,int,const void*,int,const void*),
2515   void(*xDel)(void*)
2516 ){
2517   CollSeq *pColl;
2518   int enc2;
2519 
2520   assert( sqlite3_mutex_held(db->mutex) );
2521 
2522   /* If SQLITE_UTF16 is specified as the encoding type, transform this
2523   ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
2524   ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
2525   */
2526   enc2 = enc;
2527   testcase( enc2==SQLITE_UTF16 );
2528   testcase( enc2==SQLITE_UTF16_ALIGNED );
2529   if( enc2==SQLITE_UTF16 || enc2==SQLITE_UTF16_ALIGNED ){
2530     enc2 = SQLITE_UTF16NATIVE;
2531   }
2532   if( enc2<SQLITE_UTF8 || enc2>SQLITE_UTF16BE ){
2533     return SQLITE_MISUSE_BKPT;
2534   }
2535 
2536   /* Check if this call is removing or replacing an existing collation
2537   ** sequence. If so, and there are active VMs, return busy. If there
2538   ** are no active VMs, invalidate any pre-compiled statements.
2539   */
2540   pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 0);
2541   if( pColl && pColl->xCmp ){
2542     if( db->nVdbeActive ){
2543       sqlite3ErrorWithMsg(db, SQLITE_BUSY,
2544         "unable to delete/modify collation sequence due to active statements");
2545       return SQLITE_BUSY;
2546     }
2547     sqlite3ExpirePreparedStatements(db, 0);
2548 
2549     /* If collation sequence pColl was created directly by a call to
2550     ** sqlite3_create_collation, and not generated by synthCollSeq(),
2551     ** then any copies made by synthCollSeq() need to be invalidated.
2552     ** Also, collation destructor - CollSeq.xDel() - function may need
2553     ** to be called.
2554     */
2555     if( (pColl->enc & ~SQLITE_UTF16_ALIGNED)==enc2 ){
2556       CollSeq *aColl = sqlite3HashFind(&db->aCollSeq, zName);
2557       int j;
2558       for(j=0; j<3; j++){
2559         CollSeq *p = &aColl[j];
2560         if( p->enc==pColl->enc ){
2561           if( p->xDel ){
2562             p->xDel(p->pUser);
2563           }
2564           p->xCmp = 0;
2565         }
2566       }
2567     }
2568   }
2569 
2570   pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 1);
2571   if( pColl==0 ) return SQLITE_NOMEM_BKPT;
2572   pColl->xCmp = xCompare;
2573   pColl->pUser = pCtx;
2574   pColl->xDel = xDel;
2575   pColl->enc = (u8)(enc2 | (enc & SQLITE_UTF16_ALIGNED));
2576   sqlite3Error(db, SQLITE_OK);
2577   return SQLITE_OK;
2578 }
2579 
2580 
2581 /*
2582 ** This array defines hard upper bounds on limit values.  The
2583 ** initializer must be kept in sync with the SQLITE_LIMIT_*
2584 ** #defines in sqlite3.h.
2585 */
2586 static const int aHardLimit[] = {
2587   SQLITE_MAX_LENGTH,
2588   SQLITE_MAX_SQL_LENGTH,
2589   SQLITE_MAX_COLUMN,
2590   SQLITE_MAX_EXPR_DEPTH,
2591   SQLITE_MAX_COMPOUND_SELECT,
2592   SQLITE_MAX_VDBE_OP,
2593   SQLITE_MAX_FUNCTION_ARG,
2594   SQLITE_MAX_ATTACHED,
2595   SQLITE_MAX_LIKE_PATTERN_LENGTH,
2596   SQLITE_MAX_VARIABLE_NUMBER,      /* IMP: R-38091-32352 */
2597   SQLITE_MAX_TRIGGER_DEPTH,
2598   SQLITE_MAX_WORKER_THREADS,
2599 };
2600 
2601 /*
2602 ** Make sure the hard limits are set to reasonable values
2603 */
2604 #if SQLITE_MAX_LENGTH<100
2605 # error SQLITE_MAX_LENGTH must be at least 100
2606 #endif
2607 #if SQLITE_MAX_SQL_LENGTH<100
2608 # error SQLITE_MAX_SQL_LENGTH must be at least 100
2609 #endif
2610 #if SQLITE_MAX_SQL_LENGTH>SQLITE_MAX_LENGTH
2611 # error SQLITE_MAX_SQL_LENGTH must not be greater than SQLITE_MAX_LENGTH
2612 #endif
2613 #if SQLITE_MAX_COMPOUND_SELECT<2
2614 # error SQLITE_MAX_COMPOUND_SELECT must be at least 2
2615 #endif
2616 #if SQLITE_MAX_VDBE_OP<40
2617 # error SQLITE_MAX_VDBE_OP must be at least 40
2618 #endif
2619 #if SQLITE_MAX_FUNCTION_ARG<0 || SQLITE_MAX_FUNCTION_ARG>127
2620 # error SQLITE_MAX_FUNCTION_ARG must be between 0 and 127
2621 #endif
2622 #if SQLITE_MAX_ATTACHED<0 || SQLITE_MAX_ATTACHED>125
2623 # error SQLITE_MAX_ATTACHED must be between 0 and 125
2624 #endif
2625 #if SQLITE_MAX_LIKE_PATTERN_LENGTH<1
2626 # error SQLITE_MAX_LIKE_PATTERN_LENGTH must be at least 1
2627 #endif
2628 #if SQLITE_MAX_COLUMN>32767
2629 # error SQLITE_MAX_COLUMN must not exceed 32767
2630 #endif
2631 #if SQLITE_MAX_TRIGGER_DEPTH<1
2632 # error SQLITE_MAX_TRIGGER_DEPTH must be at least 1
2633 #endif
2634 #if SQLITE_MAX_WORKER_THREADS<0 || SQLITE_MAX_WORKER_THREADS>50
2635 # error SQLITE_MAX_WORKER_THREADS must be between 0 and 50
2636 #endif
2637 
2638 
2639 /*
2640 ** Change the value of a limit.  Report the old value.
2641 ** If an invalid limit index is supplied, report -1.
2642 ** Make no changes but still report the old value if the
2643 ** new limit is negative.
2644 **
2645 ** A new lower limit does not shrink existing constructs.
2646 ** It merely prevents new constructs that exceed the limit
2647 ** from forming.
2648 */
2649 int sqlite3_limit(sqlite3 *db, int limitId, int newLimit){
2650   int oldLimit;
2651 
2652 #ifdef SQLITE_ENABLE_API_ARMOR
2653   if( !sqlite3SafetyCheckOk(db) ){
2654     (void)SQLITE_MISUSE_BKPT;
2655     return -1;
2656   }
2657 #endif
2658 
2659   /* EVIDENCE-OF: R-30189-54097 For each limit category SQLITE_LIMIT_NAME
2660   ** there is a hard upper bound set at compile-time by a C preprocessor
2661   ** macro called SQLITE_MAX_NAME. (The "_LIMIT_" in the name is changed to
2662   ** "_MAX_".)
2663   */
2664   assert( aHardLimit[SQLITE_LIMIT_LENGTH]==SQLITE_MAX_LENGTH );
2665   assert( aHardLimit[SQLITE_LIMIT_SQL_LENGTH]==SQLITE_MAX_SQL_LENGTH );
2666   assert( aHardLimit[SQLITE_LIMIT_COLUMN]==SQLITE_MAX_COLUMN );
2667   assert( aHardLimit[SQLITE_LIMIT_EXPR_DEPTH]==SQLITE_MAX_EXPR_DEPTH );
2668   assert( aHardLimit[SQLITE_LIMIT_COMPOUND_SELECT]==SQLITE_MAX_COMPOUND_SELECT);
2669   assert( aHardLimit[SQLITE_LIMIT_VDBE_OP]==SQLITE_MAX_VDBE_OP );
2670   assert( aHardLimit[SQLITE_LIMIT_FUNCTION_ARG]==SQLITE_MAX_FUNCTION_ARG );
2671   assert( aHardLimit[SQLITE_LIMIT_ATTACHED]==SQLITE_MAX_ATTACHED );
2672   assert( aHardLimit[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]==
2673                                                SQLITE_MAX_LIKE_PATTERN_LENGTH );
2674   assert( aHardLimit[SQLITE_LIMIT_VARIABLE_NUMBER]==SQLITE_MAX_VARIABLE_NUMBER);
2675   assert( aHardLimit[SQLITE_LIMIT_TRIGGER_DEPTH]==SQLITE_MAX_TRIGGER_DEPTH );
2676   assert( aHardLimit[SQLITE_LIMIT_WORKER_THREADS]==SQLITE_MAX_WORKER_THREADS );
2677   assert( SQLITE_LIMIT_WORKER_THREADS==(SQLITE_N_LIMIT-1) );
2678 
2679 
2680   if( limitId<0 || limitId>=SQLITE_N_LIMIT ){
2681     return -1;
2682   }
2683   oldLimit = db->aLimit[limitId];
2684   if( newLimit>=0 ){                   /* IMP: R-52476-28732 */
2685     if( newLimit>aHardLimit[limitId] ){
2686       newLimit = aHardLimit[limitId];  /* IMP: R-51463-25634 */
2687     }
2688     db->aLimit[limitId] = newLimit;
2689   }
2690   return oldLimit;                     /* IMP: R-53341-35419 */
2691 }
2692 
2693 /*
2694 ** This function is used to parse both URIs and non-URI filenames passed by the
2695 ** user to API functions sqlite3_open() or sqlite3_open_v2(), and for database
2696 ** URIs specified as part of ATTACH statements.
2697 **
2698 ** The first argument to this function is the name of the VFS to use (or
2699 ** a NULL to signify the default VFS) if the URI does not contain a "vfs=xxx"
2700 ** query parameter. The second argument contains the URI (or non-URI filename)
2701 ** itself. When this function is called the *pFlags variable should contain
2702 ** the default flags to open the database handle with. The value stored in
2703 ** *pFlags may be updated before returning if the URI filename contains
2704 ** "cache=xxx" or "mode=xxx" query parameters.
2705 **
2706 ** If successful, SQLITE_OK is returned. In this case *ppVfs is set to point to
2707 ** the VFS that should be used to open the database file. *pzFile is set to
2708 ** point to a buffer containing the name of the file to open. It is the
2709 ** responsibility of the caller to eventually call sqlite3_free() to release
2710 ** this buffer.
2711 **
2712 ** If an error occurs, then an SQLite error code is returned and *pzErrMsg
2713 ** may be set to point to a buffer containing an English language error
2714 ** message. It is the responsibility of the caller to eventually release
2715 ** this buffer by calling sqlite3_free().
2716 */
2717 int sqlite3ParseUri(
2718   const char *zDefaultVfs,        /* VFS to use if no "vfs=xxx" query option */
2719   const char *zUri,               /* Nul-terminated URI to parse */
2720   unsigned int *pFlags,           /* IN/OUT: SQLITE_OPEN_XXX flags */
2721   sqlite3_vfs **ppVfs,            /* OUT: VFS to use */
2722   char **pzFile,                  /* OUT: Filename component of URI */
2723   char **pzErrMsg                 /* OUT: Error message (if rc!=SQLITE_OK) */
2724 ){
2725   int rc = SQLITE_OK;
2726   unsigned int flags = *pFlags;
2727   const char *zVfs = zDefaultVfs;
2728   char *zFile;
2729   char c;
2730   int nUri = sqlite3Strlen30(zUri);
2731 
2732   assert( *pzErrMsg==0 );
2733 
2734   if( ((flags & SQLITE_OPEN_URI)             /* IMP: R-48725-32206 */
2735             || sqlite3GlobalConfig.bOpenUri) /* IMP: R-51689-46548 */
2736    && nUri>=5 && memcmp(zUri, "file:", 5)==0 /* IMP: R-57884-37496 */
2737   ){
2738     char *zOpt;
2739     int eState;                   /* Parser state when parsing URI */
2740     int iIn;                      /* Input character index */
2741     int iOut = 0;                 /* Output character index */
2742     u64 nByte = nUri+2;           /* Bytes of space to allocate */
2743 
2744     /* Make sure the SQLITE_OPEN_URI flag is set to indicate to the VFS xOpen
2745     ** method that there may be extra parameters following the file-name.  */
2746     flags |= SQLITE_OPEN_URI;
2747 
2748     for(iIn=0; iIn<nUri; iIn++) nByte += (zUri[iIn]=='&');
2749     zFile = sqlite3_malloc64(nByte);
2750     if( !zFile ) return SQLITE_NOMEM_BKPT;
2751 
2752     iIn = 5;
2753 #ifdef SQLITE_ALLOW_URI_AUTHORITY
2754     if( strncmp(zUri+5, "///", 3)==0 ){
2755       iIn = 7;
2756       /* The following condition causes URIs with five leading / characters
2757       ** like file://///host/path to be converted into UNCs like //host/path.
2758       ** The correct URI for that UNC has only two or four leading / characters
2759       ** file://host/path or file:////host/path.  But 5 leading slashes is a
2760       ** common error, we are told, so we handle it as a special case. */
2761       if( strncmp(zUri+7, "///", 3)==0 ){ iIn++; }
2762     }else if( strncmp(zUri+5, "//localhost/", 12)==0 ){
2763       iIn = 16;
2764     }
2765 #else
2766     /* Discard the scheme and authority segments of the URI. */
2767     if( zUri[5]=='/' && zUri[6]=='/' ){
2768       iIn = 7;
2769       while( zUri[iIn] && zUri[iIn]!='/' ) iIn++;
2770       if( iIn!=7 && (iIn!=16 || memcmp("localhost", &zUri[7], 9)) ){
2771         *pzErrMsg = sqlite3_mprintf("invalid uri authority: %.*s",
2772             iIn-7, &zUri[7]);
2773         rc = SQLITE_ERROR;
2774         goto parse_uri_out;
2775       }
2776     }
2777 #endif
2778 
2779     /* Copy the filename and any query parameters into the zFile buffer.
2780     ** Decode %HH escape codes along the way.
2781     **
2782     ** Within this loop, variable eState may be set to 0, 1 or 2, depending
2783     ** on the parsing context. As follows:
2784     **
2785     **   0: Parsing file-name.
2786     **   1: Parsing name section of a name=value query parameter.
2787     **   2: Parsing value section of a name=value query parameter.
2788     */
2789     eState = 0;
2790     while( (c = zUri[iIn])!=0 && c!='#' ){
2791       iIn++;
2792       if( c=='%'
2793        && sqlite3Isxdigit(zUri[iIn])
2794        && sqlite3Isxdigit(zUri[iIn+1])
2795       ){
2796         int octet = (sqlite3HexToInt(zUri[iIn++]) << 4);
2797         octet += sqlite3HexToInt(zUri[iIn++]);
2798 
2799         assert( octet>=0 && octet<256 );
2800         if( octet==0 ){
2801 #ifndef SQLITE_ENABLE_URI_00_ERROR
2802           /* This branch is taken when "%00" appears within the URI. In this
2803           ** case we ignore all text in the remainder of the path, name or
2804           ** value currently being parsed. So ignore the current character
2805           ** and skip to the next "?", "=" or "&", as appropriate. */
2806           while( (c = zUri[iIn])!=0 && c!='#'
2807               && (eState!=0 || c!='?')
2808               && (eState!=1 || (c!='=' && c!='&'))
2809               && (eState!=2 || c!='&')
2810           ){
2811             iIn++;
2812           }
2813           continue;
2814 #else
2815           /* If ENABLE_URI_00_ERROR is defined, "%00" in a URI is an error. */
2816           *pzErrMsg = sqlite3_mprintf("unexpected %%00 in uri");
2817           rc = SQLITE_ERROR;
2818           goto parse_uri_out;
2819 #endif
2820         }
2821         c = octet;
2822       }else if( eState==1 && (c=='&' || c=='=') ){
2823         if( zFile[iOut-1]==0 ){
2824           /* An empty option name. Ignore this option altogether. */
2825           while( zUri[iIn] && zUri[iIn]!='#' && zUri[iIn-1]!='&' ) iIn++;
2826           continue;
2827         }
2828         if( c=='&' ){
2829           zFile[iOut++] = '\0';
2830         }else{
2831           eState = 2;
2832         }
2833         c = 0;
2834       }else if( (eState==0 && c=='?') || (eState==2 && c=='&') ){
2835         c = 0;
2836         eState = 1;
2837       }
2838       zFile[iOut++] = c;
2839     }
2840     if( eState==1 ) zFile[iOut++] = '\0';
2841     zFile[iOut++] = '\0';
2842     zFile[iOut++] = '\0';
2843 
2844     /* Check if there were any options specified that should be interpreted
2845     ** here. Options that are interpreted here include "vfs" and those that
2846     ** correspond to flags that may be passed to the sqlite3_open_v2()
2847     ** method. */
2848     zOpt = &zFile[sqlite3Strlen30(zFile)+1];
2849     while( zOpt[0] ){
2850       int nOpt = sqlite3Strlen30(zOpt);
2851       char *zVal = &zOpt[nOpt+1];
2852       int nVal = sqlite3Strlen30(zVal);
2853 
2854       if( nOpt==3 && memcmp("vfs", zOpt, 3)==0 ){
2855         zVfs = zVal;
2856       }else{
2857         struct OpenMode {
2858           const char *z;
2859           int mode;
2860         } *aMode = 0;
2861         char *zModeType = 0;
2862         int mask = 0;
2863         int limit = 0;
2864 
2865         if( nOpt==5 && memcmp("cache", zOpt, 5)==0 ){
2866           static struct OpenMode aCacheMode[] = {
2867             { "shared",  SQLITE_OPEN_SHAREDCACHE },
2868             { "private", SQLITE_OPEN_PRIVATECACHE },
2869             { 0, 0 }
2870           };
2871 
2872           mask = SQLITE_OPEN_SHAREDCACHE|SQLITE_OPEN_PRIVATECACHE;
2873           aMode = aCacheMode;
2874           limit = mask;
2875           zModeType = "cache";
2876         }
2877         if( nOpt==4 && memcmp("mode", zOpt, 4)==0 ){
2878           static struct OpenMode aOpenMode[] = {
2879             { "ro",  SQLITE_OPEN_READONLY },
2880             { "rw",  SQLITE_OPEN_READWRITE },
2881             { "rwc", SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE },
2882             { "memory", SQLITE_OPEN_MEMORY },
2883             { 0, 0 }
2884           };
2885 
2886           mask = SQLITE_OPEN_READONLY | SQLITE_OPEN_READWRITE
2887                    | SQLITE_OPEN_CREATE | SQLITE_OPEN_MEMORY;
2888           aMode = aOpenMode;
2889           limit = mask & flags;
2890           zModeType = "access";
2891         }
2892 
2893         if( aMode ){
2894           int i;
2895           int mode = 0;
2896           for(i=0; aMode[i].z; i++){
2897             const char *z = aMode[i].z;
2898             if( nVal==sqlite3Strlen30(z) && 0==memcmp(zVal, z, nVal) ){
2899               mode = aMode[i].mode;
2900               break;
2901             }
2902           }
2903           if( mode==0 ){
2904             *pzErrMsg = sqlite3_mprintf("no such %s mode: %s", zModeType, zVal);
2905             rc = SQLITE_ERROR;
2906             goto parse_uri_out;
2907           }
2908           if( (mode & ~SQLITE_OPEN_MEMORY)>limit ){
2909             *pzErrMsg = sqlite3_mprintf("%s mode not allowed: %s",
2910                                         zModeType, zVal);
2911             rc = SQLITE_PERM;
2912             goto parse_uri_out;
2913           }
2914           flags = (flags & ~mask) | mode;
2915         }
2916       }
2917 
2918       zOpt = &zVal[nVal+1];
2919     }
2920 
2921   }else{
2922     zFile = sqlite3_malloc64(nUri+2);
2923     if( !zFile ) return SQLITE_NOMEM_BKPT;
2924     if( nUri ){
2925       memcpy(zFile, zUri, nUri);
2926     }
2927     zFile[nUri] = '\0';
2928     zFile[nUri+1] = '\0';
2929     flags &= ~SQLITE_OPEN_URI;
2930   }
2931 
2932   *ppVfs = sqlite3_vfs_find(zVfs);
2933   if( *ppVfs==0 ){
2934     *pzErrMsg = sqlite3_mprintf("no such vfs: %s", zVfs);
2935     rc = SQLITE_ERROR;
2936   }
2937  parse_uri_out:
2938   if( rc!=SQLITE_OK ){
2939     sqlite3_free(zFile);
2940     zFile = 0;
2941   }
2942   *pFlags = flags;
2943   *pzFile = zFile;
2944   return rc;
2945 }
2946 
2947 #if defined(SQLITE_HAS_CODEC)
2948 /*
2949 ** Process URI filename query parameters relevant to the SQLite Encryption
2950 ** Extension.  Return true if any of the relevant query parameters are
2951 ** seen and return false if not.
2952 */
2953 int sqlite3CodecQueryParameters(
2954   sqlite3 *db,           /* Database connection */
2955   const char *zDb,       /* Which schema is being created/attached */
2956   const char *zUri       /* URI filename */
2957 ){
2958   const char *zKey;
2959   if( (zKey = sqlite3_uri_parameter(zUri, "hexkey"))!=0 && zKey[0] ){
2960     u8 iByte;
2961     int i;
2962     char zDecoded[40];
2963     for(i=0, iByte=0; i<sizeof(zDecoded)*2 && sqlite3Isxdigit(zKey[i]); i++){
2964       iByte = (iByte<<4) + sqlite3HexToInt(zKey[i]);
2965       if( (i&1)!=0 ) zDecoded[i/2] = iByte;
2966     }
2967     sqlite3_key_v2(db, zDb, zDecoded, i/2);
2968     return 1;
2969   }else if( (zKey = sqlite3_uri_parameter(zUri, "key"))!=0 ){
2970     sqlite3_key_v2(db, zDb, zKey, sqlite3Strlen30(zKey));
2971     return 1;
2972   }else if( (zKey = sqlite3_uri_parameter(zUri, "textkey"))!=0 ){
2973     sqlite3_key_v2(db, zDb, zKey, -1);
2974     return 1;
2975   }else{
2976     return 0;
2977   }
2978 }
2979 #endif
2980 
2981 
2982 /*
2983 ** This routine does the work of opening a database on behalf of
2984 ** sqlite3_open() and sqlite3_open16(). The database filename "zFilename"
2985 ** is UTF-8 encoded.
2986 */
2987 static int openDatabase(
2988   const char *zFilename, /* Database filename UTF-8 encoded */
2989   sqlite3 **ppDb,        /* OUT: Returned database handle */
2990   unsigned int flags,    /* Operational flags */
2991   const char *zVfs       /* Name of the VFS to use */
2992 ){
2993   sqlite3 *db;                    /* Store allocated handle here */
2994   int rc;                         /* Return code */
2995   int isThreadsafe;               /* True for threadsafe connections */
2996   char *zOpen = 0;                /* Filename argument to pass to BtreeOpen() */
2997   char *zErrMsg = 0;              /* Error message from sqlite3ParseUri() */
2998 
2999 #ifdef SQLITE_ENABLE_API_ARMOR
3000   if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
3001 #endif
3002   *ppDb = 0;
3003 #ifndef SQLITE_OMIT_AUTOINIT
3004   rc = sqlite3_initialize();
3005   if( rc ) return rc;
3006 #endif
3007 
3008   if( sqlite3GlobalConfig.bCoreMutex==0 ){
3009     isThreadsafe = 0;
3010   }else if( flags & SQLITE_OPEN_NOMUTEX ){
3011     isThreadsafe = 0;
3012   }else if( flags & SQLITE_OPEN_FULLMUTEX ){
3013     isThreadsafe = 1;
3014   }else{
3015     isThreadsafe = sqlite3GlobalConfig.bFullMutex;
3016   }
3017 
3018   if( flags & SQLITE_OPEN_PRIVATECACHE ){
3019     flags &= ~SQLITE_OPEN_SHAREDCACHE;
3020   }else if( sqlite3GlobalConfig.sharedCacheEnabled ){
3021     flags |= SQLITE_OPEN_SHAREDCACHE;
3022   }
3023 
3024   /* Remove harmful bits from the flags parameter
3025   **
3026   ** The SQLITE_OPEN_NOMUTEX and SQLITE_OPEN_FULLMUTEX flags were
3027   ** dealt with in the previous code block.  Besides these, the only
3028   ** valid input flags for sqlite3_open_v2() are SQLITE_OPEN_READONLY,
3029   ** SQLITE_OPEN_READWRITE, SQLITE_OPEN_CREATE, SQLITE_OPEN_SHAREDCACHE,
3030   ** SQLITE_OPEN_PRIVATECACHE, and some reserved bits.  Silently mask
3031   ** off all other flags.
3032   */
3033   flags &=  ~( SQLITE_OPEN_DELETEONCLOSE |
3034                SQLITE_OPEN_EXCLUSIVE |
3035                SQLITE_OPEN_MAIN_DB |
3036                SQLITE_OPEN_TEMP_DB |
3037                SQLITE_OPEN_TRANSIENT_DB |
3038                SQLITE_OPEN_MAIN_JOURNAL |
3039                SQLITE_OPEN_TEMP_JOURNAL |
3040                SQLITE_OPEN_SUBJOURNAL |
3041                SQLITE_OPEN_MASTER_JOURNAL |
3042                SQLITE_OPEN_NOMUTEX |
3043                SQLITE_OPEN_FULLMUTEX |
3044                SQLITE_OPEN_WAL
3045              );
3046 
3047   /* Allocate the sqlite data structure */
3048   db = sqlite3MallocZero( sizeof(sqlite3) );
3049   if( db==0 ) goto opendb_out;
3050   if( isThreadsafe
3051 #ifdef SQLITE_ENABLE_MULTITHREADED_CHECKS
3052    || sqlite3GlobalConfig.bCoreMutex
3053 #endif
3054   ){
3055     db->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
3056     if( db->mutex==0 ){
3057       sqlite3_free(db);
3058       db = 0;
3059       goto opendb_out;
3060     }
3061     if( isThreadsafe==0 ){
3062       sqlite3MutexWarnOnContention(db->mutex);
3063     }
3064   }
3065   sqlite3_mutex_enter(db->mutex);
3066   db->errMask = 0xff;
3067   db->nDb = 2;
3068   db->magic = SQLITE_MAGIC_BUSY;
3069   db->aDb = db->aDbStatic;
3070   db->lookaside.bDisable = 1;
3071   db->lookaside.sz = 0;
3072 
3073   assert( sizeof(db->aLimit)==sizeof(aHardLimit) );
3074   memcpy(db->aLimit, aHardLimit, sizeof(db->aLimit));
3075   db->aLimit[SQLITE_LIMIT_WORKER_THREADS] = SQLITE_DEFAULT_WORKER_THREADS;
3076   db->autoCommit = 1;
3077   db->nextAutovac = -1;
3078   db->szMmap = sqlite3GlobalConfig.szMmap;
3079   db->nextPagesize = 0;
3080   db->nMaxSorterMmap = 0x7FFFFFFF;
3081   db->flags |= SQLITE_ShortColNames
3082                  | SQLITE_EnableTrigger
3083                  | SQLITE_EnableView
3084                  | SQLITE_CacheSpill
3085 
3086 /* The SQLITE_DQS compile-time option determines the default settings
3087 ** for SQLITE_DBCONFIG_DQS_DDL and SQLITE_DBCONFIG_DQS_DML.
3088 **
3089 **    SQLITE_DQS     SQLITE_DBCONFIG_DQS_DDL    SQLITE_DBCONFIG_DQS_DML
3090 **    ----------     -----------------------    -----------------------
3091 **     undefined               on                          on
3092 **         3                   on                          on
3093 **         2                   on                         off
3094 **         1                  off                          on
3095 **         0                  off                         off
3096 **
3097 ** Legacy behavior is 3 (double-quoted string literals are allowed anywhere)
3098 ** and so that is the default.  But developers are encouranged to use
3099 ** -DSQLITE_DQS=0 (best) or -DSQLITE_DQS=1 (second choice) if possible.
3100 */
3101 #if !defined(SQLITE_DQS)
3102 # define SQLITE_DQS 3
3103 #endif
3104 #if (SQLITE_DQS&1)==1
3105                  | SQLITE_DqsDML
3106 #endif
3107 #if (SQLITE_DQS&2)==2
3108                  | SQLITE_DqsDDL
3109 #endif
3110 
3111 #if !defined(SQLITE_DEFAULT_AUTOMATIC_INDEX) || SQLITE_DEFAULT_AUTOMATIC_INDEX
3112                  | SQLITE_AutoIndex
3113 #endif
3114 #if SQLITE_DEFAULT_CKPTFULLFSYNC
3115                  | SQLITE_CkptFullFSync
3116 #endif
3117 #if SQLITE_DEFAULT_FILE_FORMAT<4
3118                  | SQLITE_LegacyFileFmt
3119 #endif
3120 #ifdef SQLITE_ENABLE_LOAD_EXTENSION
3121                  | SQLITE_LoadExtension
3122 #endif
3123 #if SQLITE_DEFAULT_RECURSIVE_TRIGGERS
3124                  | SQLITE_RecTriggers
3125 #endif
3126 #if defined(SQLITE_DEFAULT_FOREIGN_KEYS) && SQLITE_DEFAULT_FOREIGN_KEYS
3127                  | SQLITE_ForeignKeys
3128 #endif
3129 #if defined(SQLITE_REVERSE_UNORDERED_SELECTS)
3130                  | SQLITE_ReverseOrder
3131 #endif
3132 #if defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
3133                  | SQLITE_CellSizeCk
3134 #endif
3135 #if defined(SQLITE_ENABLE_FTS3_TOKENIZER)
3136                  | SQLITE_Fts3Tokenizer
3137 #endif
3138 #if defined(SQLITE_ENABLE_QPSG)
3139                  | SQLITE_EnableQPSG
3140 #endif
3141 #if defined(SQLITE_DEFAULT_DEFENSIVE)
3142                  | SQLITE_Defensive
3143 #endif
3144       ;
3145   sqlite3HashInit(&db->aCollSeq);
3146 #ifndef SQLITE_OMIT_VIRTUALTABLE
3147   sqlite3HashInit(&db->aModule);
3148 #endif
3149 
3150   /* Add the default collation sequence BINARY. BINARY works for both UTF-8
3151   ** and UTF-16, so add a version for each to avoid any unnecessary
3152   ** conversions. The only error that can occur here is a malloc() failure.
3153   **
3154   ** EVIDENCE-OF: R-52786-44878 SQLite defines three built-in collating
3155   ** functions:
3156   */
3157   createCollation(db, sqlite3StrBINARY, SQLITE_UTF8, 0, binCollFunc, 0);
3158   createCollation(db, sqlite3StrBINARY, SQLITE_UTF16BE, 0, binCollFunc, 0);
3159   createCollation(db, sqlite3StrBINARY, SQLITE_UTF16LE, 0, binCollFunc, 0);
3160   createCollation(db, "NOCASE", SQLITE_UTF8, 0, nocaseCollatingFunc, 0);
3161   createCollation(db, "RTRIM", SQLITE_UTF8, 0, rtrimCollFunc, 0);
3162   if( db->mallocFailed ){
3163     goto opendb_out;
3164   }
3165   /* EVIDENCE-OF: R-08308-17224 The default collating function for all
3166   ** strings is BINARY.
3167   */
3168   db->pDfltColl = sqlite3FindCollSeq(db, SQLITE_UTF8, sqlite3StrBINARY, 0);
3169   assert( db->pDfltColl!=0 );
3170 
3171   /* Parse the filename/URI argument
3172   **
3173   ** Only allow sensible combinations of bits in the flags argument.
3174   ** Throw an error if any non-sense combination is used.  If we
3175   ** do not block illegal combinations here, it could trigger
3176   ** assert() statements in deeper layers.  Sensible combinations
3177   ** are:
3178   **
3179   **  1:  SQLITE_OPEN_READONLY
3180   **  2:  SQLITE_OPEN_READWRITE
3181   **  6:  SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE
3182   */
3183   db->openFlags = flags;
3184   assert( SQLITE_OPEN_READONLY  == 0x01 );
3185   assert( SQLITE_OPEN_READWRITE == 0x02 );
3186   assert( SQLITE_OPEN_CREATE    == 0x04 );
3187   testcase( (1<<(flags&7))==0x02 ); /* READONLY */
3188   testcase( (1<<(flags&7))==0x04 ); /* READWRITE */
3189   testcase( (1<<(flags&7))==0x40 ); /* READWRITE | CREATE */
3190   if( ((1<<(flags&7)) & 0x46)==0 ){
3191     rc = SQLITE_MISUSE_BKPT;  /* IMP: R-65497-44594 */
3192   }else{
3193     rc = sqlite3ParseUri(zVfs, zFilename, &flags, &db->pVfs, &zOpen, &zErrMsg);
3194   }
3195   if( rc!=SQLITE_OK ){
3196     if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
3197     sqlite3ErrorWithMsg(db, rc, zErrMsg ? "%s" : 0, zErrMsg);
3198     sqlite3_free(zErrMsg);
3199     goto opendb_out;
3200   }
3201 
3202   /* Open the backend database driver */
3203   rc = sqlite3BtreeOpen(db->pVfs, zOpen, db, &db->aDb[0].pBt, 0,
3204                         flags | SQLITE_OPEN_MAIN_DB);
3205   if( rc!=SQLITE_OK ){
3206     if( rc==SQLITE_IOERR_NOMEM ){
3207       rc = SQLITE_NOMEM_BKPT;
3208     }
3209     sqlite3Error(db, rc);
3210     goto opendb_out;
3211   }
3212   sqlite3BtreeEnter(db->aDb[0].pBt);
3213   db->aDb[0].pSchema = sqlite3SchemaGet(db, db->aDb[0].pBt);
3214   if( !db->mallocFailed ) ENC(db) = SCHEMA_ENC(db);
3215   sqlite3BtreeLeave(db->aDb[0].pBt);
3216   db->aDb[1].pSchema = sqlite3SchemaGet(db, 0);
3217 
3218   /* The default safety_level for the main database is FULL; for the temp
3219   ** database it is OFF. This matches the pager layer defaults.
3220   */
3221   db->aDb[0].zDbSName = "main";
3222   db->aDb[0].safety_level = SQLITE_DEFAULT_SYNCHRONOUS+1;
3223   db->aDb[1].zDbSName = "temp";
3224   db->aDb[1].safety_level = PAGER_SYNCHRONOUS_OFF;
3225 
3226   db->magic = SQLITE_MAGIC_OPEN;
3227   if( db->mallocFailed ){
3228     goto opendb_out;
3229   }
3230 
3231   /* Register all built-in functions, but do not attempt to read the
3232   ** database schema yet. This is delayed until the first time the database
3233   ** is accessed.
3234   */
3235   sqlite3Error(db, SQLITE_OK);
3236   sqlite3RegisterPerConnectionBuiltinFunctions(db);
3237   rc = sqlite3_errcode(db);
3238 
3239 #ifdef SQLITE_ENABLE_FTS5
3240   /* Register any built-in FTS5 module before loading the automatic
3241   ** extensions. This allows automatic extensions to register FTS5
3242   ** tokenizers and auxiliary functions.  */
3243   if( !db->mallocFailed && rc==SQLITE_OK ){
3244     rc = sqlite3Fts5Init(db);
3245   }
3246 #endif
3247 
3248   /* Load automatic extensions - extensions that have been registered
3249   ** using the sqlite3_automatic_extension() API.
3250   */
3251   if( rc==SQLITE_OK ){
3252     sqlite3AutoLoadExtensions(db);
3253     rc = sqlite3_errcode(db);
3254     if( rc!=SQLITE_OK ){
3255       goto opendb_out;
3256     }
3257   }
3258 
3259 #ifdef SQLITE_ENABLE_FTS1
3260   if( !db->mallocFailed ){
3261     extern int sqlite3Fts1Init(sqlite3*);
3262     rc = sqlite3Fts1Init(db);
3263   }
3264 #endif
3265 
3266 #ifdef SQLITE_ENABLE_FTS2
3267   if( !db->mallocFailed && rc==SQLITE_OK ){
3268     extern int sqlite3Fts2Init(sqlite3*);
3269     rc = sqlite3Fts2Init(db);
3270   }
3271 #endif
3272 
3273 #ifdef SQLITE_ENABLE_FTS3 /* automatically defined by SQLITE_ENABLE_FTS4 */
3274   if( !db->mallocFailed && rc==SQLITE_OK ){
3275     rc = sqlite3Fts3Init(db);
3276   }
3277 #endif
3278 
3279 #if defined(SQLITE_ENABLE_ICU) || defined(SQLITE_ENABLE_ICU_COLLATIONS)
3280   if( !db->mallocFailed && rc==SQLITE_OK ){
3281     rc = sqlite3IcuInit(db);
3282   }
3283 #endif
3284 
3285 #ifdef SQLITE_ENABLE_RTREE
3286   if( !db->mallocFailed && rc==SQLITE_OK){
3287     rc = sqlite3RtreeInit(db);
3288   }
3289 #endif
3290 
3291 #ifdef SQLITE_ENABLE_DBPAGE_VTAB
3292   if( !db->mallocFailed && rc==SQLITE_OK){
3293     rc = sqlite3DbpageRegister(db);
3294   }
3295 #endif
3296 
3297 #ifdef SQLITE_ENABLE_DBSTAT_VTAB
3298   if( !db->mallocFailed && rc==SQLITE_OK){
3299     rc = sqlite3DbstatRegister(db);
3300   }
3301 #endif
3302 
3303 #ifdef SQLITE_ENABLE_JSON1
3304   if( !db->mallocFailed && rc==SQLITE_OK){
3305     rc = sqlite3Json1Init(db);
3306   }
3307 #endif
3308 
3309 #ifdef SQLITE_ENABLE_STMTVTAB
3310   if( !db->mallocFailed && rc==SQLITE_OK){
3311     rc = sqlite3StmtVtabInit(db);
3312   }
3313 #endif
3314 
3315   /* -DSQLITE_DEFAULT_LOCKING_MODE=1 makes EXCLUSIVE the default locking
3316   ** mode.  -DSQLITE_DEFAULT_LOCKING_MODE=0 make NORMAL the default locking
3317   ** mode.  Doing nothing at all also makes NORMAL the default.
3318   */
3319 #ifdef SQLITE_DEFAULT_LOCKING_MODE
3320   db->dfltLockMode = SQLITE_DEFAULT_LOCKING_MODE;
3321   sqlite3PagerLockingMode(sqlite3BtreePager(db->aDb[0].pBt),
3322                           SQLITE_DEFAULT_LOCKING_MODE);
3323 #endif
3324 
3325   if( rc ) sqlite3Error(db, rc);
3326 
3327   /* Enable the lookaside-malloc subsystem */
3328   setupLookaside(db, 0, sqlite3GlobalConfig.szLookaside,
3329                         sqlite3GlobalConfig.nLookaside);
3330 
3331   sqlite3_wal_autocheckpoint(db, SQLITE_DEFAULT_WAL_AUTOCHECKPOINT);
3332 
3333 opendb_out:
3334   if( db ){
3335     assert( db->mutex!=0 || isThreadsafe==0
3336            || sqlite3GlobalConfig.bFullMutex==0 );
3337     sqlite3_mutex_leave(db->mutex);
3338   }
3339   rc = sqlite3_errcode(db);
3340   assert( db!=0 || rc==SQLITE_NOMEM );
3341   if( rc==SQLITE_NOMEM ){
3342     sqlite3_close(db);
3343     db = 0;
3344   }else if( rc!=SQLITE_OK ){
3345     db->magic = SQLITE_MAGIC_SICK;
3346   }
3347   *ppDb = db;
3348 #ifdef SQLITE_ENABLE_SQLLOG
3349   if( sqlite3GlobalConfig.xSqllog ){
3350     /* Opening a db handle. Fourth parameter is passed 0. */
3351     void *pArg = sqlite3GlobalConfig.pSqllogArg;
3352     sqlite3GlobalConfig.xSqllog(pArg, db, zFilename, 0);
3353   }
3354 #endif
3355 #if defined(SQLITE_HAS_CODEC)
3356   if( rc==SQLITE_OK ) sqlite3CodecQueryParameters(db, 0, zOpen);
3357 #endif
3358   sqlite3_free(zOpen);
3359   return rc & 0xff;
3360 }
3361 
3362 
3363 /*
3364 ** Open a new database handle.
3365 */
3366 int sqlite3_open(
3367   const char *zFilename,
3368   sqlite3 **ppDb
3369 ){
3370   return openDatabase(zFilename, ppDb,
3371                       SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0);
3372 }
3373 int sqlite3_open_v2(
3374   const char *filename,   /* Database filename (UTF-8) */
3375   sqlite3 **ppDb,         /* OUT: SQLite db handle */
3376   int flags,              /* Flags */
3377   const char *zVfs        /* Name of VFS module to use */
3378 ){
3379   return openDatabase(filename, ppDb, (unsigned int)flags, zVfs);
3380 }
3381 
3382 #ifndef SQLITE_OMIT_UTF16
3383 /*
3384 ** Open a new database handle.
3385 */
3386 int sqlite3_open16(
3387   const void *zFilename,
3388   sqlite3 **ppDb
3389 ){
3390   char const *zFilename8;   /* zFilename encoded in UTF-8 instead of UTF-16 */
3391   sqlite3_value *pVal;
3392   int rc;
3393 
3394 #ifdef SQLITE_ENABLE_API_ARMOR
3395   if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
3396 #endif
3397   *ppDb = 0;
3398 #ifndef SQLITE_OMIT_AUTOINIT
3399   rc = sqlite3_initialize();
3400   if( rc ) return rc;
3401 #endif
3402   if( zFilename==0 ) zFilename = "\000\000";
3403   pVal = sqlite3ValueNew(0);
3404   sqlite3ValueSetStr(pVal, -1, zFilename, SQLITE_UTF16NATIVE, SQLITE_STATIC);
3405   zFilename8 = sqlite3ValueText(pVal, SQLITE_UTF8);
3406   if( zFilename8 ){
3407     rc = openDatabase(zFilename8, ppDb,
3408                       SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0);
3409     assert( *ppDb || rc==SQLITE_NOMEM );
3410     if( rc==SQLITE_OK && !DbHasProperty(*ppDb, 0, DB_SchemaLoaded) ){
3411       SCHEMA_ENC(*ppDb) = ENC(*ppDb) = SQLITE_UTF16NATIVE;
3412     }
3413   }else{
3414     rc = SQLITE_NOMEM_BKPT;
3415   }
3416   sqlite3ValueFree(pVal);
3417 
3418   return rc & 0xff;
3419 }
3420 #endif /* SQLITE_OMIT_UTF16 */
3421 
3422 /*
3423 ** Register a new collation sequence with the database handle db.
3424 */
3425 int sqlite3_create_collation(
3426   sqlite3* db,
3427   const char *zName,
3428   int enc,
3429   void* pCtx,
3430   int(*xCompare)(void*,int,const void*,int,const void*)
3431 ){
3432   return sqlite3_create_collation_v2(db, zName, enc, pCtx, xCompare, 0);
3433 }
3434 
3435 /*
3436 ** Register a new collation sequence with the database handle db.
3437 */
3438 int sqlite3_create_collation_v2(
3439   sqlite3* db,
3440   const char *zName,
3441   int enc,
3442   void* pCtx,
3443   int(*xCompare)(void*,int,const void*,int,const void*),
3444   void(*xDel)(void*)
3445 ){
3446   int rc;
3447 
3448 #ifdef SQLITE_ENABLE_API_ARMOR
3449   if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
3450 #endif
3451   sqlite3_mutex_enter(db->mutex);
3452   assert( !db->mallocFailed );
3453   rc = createCollation(db, zName, (u8)enc, pCtx, xCompare, xDel);
3454   rc = sqlite3ApiExit(db, rc);
3455   sqlite3_mutex_leave(db->mutex);
3456   return rc;
3457 }
3458 
3459 #ifndef SQLITE_OMIT_UTF16
3460 /*
3461 ** Register a new collation sequence with the database handle db.
3462 */
3463 int sqlite3_create_collation16(
3464   sqlite3* db,
3465   const void *zName,
3466   int enc,
3467   void* pCtx,
3468   int(*xCompare)(void*,int,const void*,int,const void*)
3469 ){
3470   int rc = SQLITE_OK;
3471   char *zName8;
3472 
3473 #ifdef SQLITE_ENABLE_API_ARMOR
3474   if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
3475 #endif
3476   sqlite3_mutex_enter(db->mutex);
3477   assert( !db->mallocFailed );
3478   zName8 = sqlite3Utf16to8(db, zName, -1, SQLITE_UTF16NATIVE);
3479   if( zName8 ){
3480     rc = createCollation(db, zName8, (u8)enc, pCtx, xCompare, 0);
3481     sqlite3DbFree(db, zName8);
3482   }
3483   rc = sqlite3ApiExit(db, rc);
3484   sqlite3_mutex_leave(db->mutex);
3485   return rc;
3486 }
3487 #endif /* SQLITE_OMIT_UTF16 */
3488 
3489 /*
3490 ** Register a collation sequence factory callback with the database handle
3491 ** db. Replace any previously installed collation sequence factory.
3492 */
3493 int sqlite3_collation_needed(
3494   sqlite3 *db,
3495   void *pCollNeededArg,
3496   void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*)
3497 ){
3498 #ifdef SQLITE_ENABLE_API_ARMOR
3499   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3500 #endif
3501   sqlite3_mutex_enter(db->mutex);
3502   db->xCollNeeded = xCollNeeded;
3503   db->xCollNeeded16 = 0;
3504   db->pCollNeededArg = pCollNeededArg;
3505   sqlite3_mutex_leave(db->mutex);
3506   return SQLITE_OK;
3507 }
3508 
3509 #ifndef SQLITE_OMIT_UTF16
3510 /*
3511 ** Register a collation sequence factory callback with the database handle
3512 ** db. Replace any previously installed collation sequence factory.
3513 */
3514 int sqlite3_collation_needed16(
3515   sqlite3 *db,
3516   void *pCollNeededArg,
3517   void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*)
3518 ){
3519 #ifdef SQLITE_ENABLE_API_ARMOR
3520   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3521 #endif
3522   sqlite3_mutex_enter(db->mutex);
3523   db->xCollNeeded = 0;
3524   db->xCollNeeded16 = xCollNeeded16;
3525   db->pCollNeededArg = pCollNeededArg;
3526   sqlite3_mutex_leave(db->mutex);
3527   return SQLITE_OK;
3528 }
3529 #endif /* SQLITE_OMIT_UTF16 */
3530 
3531 #ifndef SQLITE_OMIT_DEPRECATED
3532 /*
3533 ** This function is now an anachronism. It used to be used to recover from a
3534 ** malloc() failure, but SQLite now does this automatically.
3535 */
3536 int sqlite3_global_recover(void){
3537   return SQLITE_OK;
3538 }
3539 #endif
3540 
3541 /*
3542 ** Test to see whether or not the database connection is in autocommit
3543 ** mode.  Return TRUE if it is and FALSE if not.  Autocommit mode is on
3544 ** by default.  Autocommit is disabled by a BEGIN statement and reenabled
3545 ** by the next COMMIT or ROLLBACK.
3546 */
3547 int sqlite3_get_autocommit(sqlite3 *db){
3548 #ifdef SQLITE_ENABLE_API_ARMOR
3549   if( !sqlite3SafetyCheckOk(db) ){
3550     (void)SQLITE_MISUSE_BKPT;
3551     return 0;
3552   }
3553 #endif
3554   return db->autoCommit;
3555 }
3556 
3557 /*
3558 ** The following routines are substitutes for constants SQLITE_CORRUPT,
3559 ** SQLITE_MISUSE, SQLITE_CANTOPEN, SQLITE_NOMEM and possibly other error
3560 ** constants.  They serve two purposes:
3561 **
3562 **   1.  Serve as a convenient place to set a breakpoint in a debugger
3563 **       to detect when version error conditions occurs.
3564 **
3565 **   2.  Invoke sqlite3_log() to provide the source code location where
3566 **       a low-level error is first detected.
3567 */
3568 int sqlite3ReportError(int iErr, int lineno, const char *zType){
3569   sqlite3_log(iErr, "%s at line %d of [%.10s]",
3570               zType, lineno, 20+sqlite3_sourceid());
3571   return iErr;
3572 }
3573 int sqlite3CorruptError(int lineno){
3574   testcase( sqlite3GlobalConfig.xLog!=0 );
3575   return sqlite3ReportError(SQLITE_CORRUPT, lineno, "database corruption");
3576 }
3577 int sqlite3MisuseError(int lineno){
3578   testcase( sqlite3GlobalConfig.xLog!=0 );
3579   return sqlite3ReportError(SQLITE_MISUSE, lineno, "misuse");
3580 }
3581 int sqlite3CantopenError(int lineno){
3582   testcase( sqlite3GlobalConfig.xLog!=0 );
3583   return sqlite3ReportError(SQLITE_CANTOPEN, lineno, "cannot open file");
3584 }
3585 #ifdef SQLITE_DEBUG
3586 int sqlite3CorruptPgnoError(int lineno, Pgno pgno){
3587   char zMsg[100];
3588   sqlite3_snprintf(sizeof(zMsg), zMsg, "database corruption page %d", pgno);
3589   testcase( sqlite3GlobalConfig.xLog!=0 );
3590   return sqlite3ReportError(SQLITE_CORRUPT, lineno, zMsg);
3591 }
3592 int sqlite3NomemError(int lineno){
3593   testcase( sqlite3GlobalConfig.xLog!=0 );
3594   return sqlite3ReportError(SQLITE_NOMEM, lineno, "OOM");
3595 }
3596 int sqlite3IoerrnomemError(int lineno){
3597   testcase( sqlite3GlobalConfig.xLog!=0 );
3598   return sqlite3ReportError(SQLITE_IOERR_NOMEM, lineno, "I/O OOM error");
3599 }
3600 #endif
3601 
3602 #ifndef SQLITE_OMIT_DEPRECATED
3603 /*
3604 ** This is a convenience routine that makes sure that all thread-specific
3605 ** data for this thread has been deallocated.
3606 **
3607 ** SQLite no longer uses thread-specific data so this routine is now a
3608 ** no-op.  It is retained for historical compatibility.
3609 */
3610 void sqlite3_thread_cleanup(void){
3611 }
3612 #endif
3613 
3614 /*
3615 ** Return meta information about a specific column of a database table.
3616 ** See comment in sqlite3.h (sqlite.h.in) for details.
3617 */
3618 int sqlite3_table_column_metadata(
3619   sqlite3 *db,                /* Connection handle */
3620   const char *zDbName,        /* Database name or NULL */
3621   const char *zTableName,     /* Table name */
3622   const char *zColumnName,    /* Column name */
3623   char const **pzDataType,    /* OUTPUT: Declared data type */
3624   char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
3625   int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
3626   int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
3627   int *pAutoinc               /* OUTPUT: True if column is auto-increment */
3628 ){
3629   int rc;
3630   char *zErrMsg = 0;
3631   Table *pTab = 0;
3632   Column *pCol = 0;
3633   int iCol = 0;
3634   char const *zDataType = 0;
3635   char const *zCollSeq = 0;
3636   int notnull = 0;
3637   int primarykey = 0;
3638   int autoinc = 0;
3639 
3640 
3641 #ifdef SQLITE_ENABLE_API_ARMOR
3642   if( !sqlite3SafetyCheckOk(db) || zTableName==0 ){
3643     return SQLITE_MISUSE_BKPT;
3644   }
3645 #endif
3646 
3647   /* Ensure the database schema has been loaded */
3648   sqlite3_mutex_enter(db->mutex);
3649   sqlite3BtreeEnterAll(db);
3650   rc = sqlite3Init(db, &zErrMsg);
3651   if( SQLITE_OK!=rc ){
3652     goto error_out;
3653   }
3654 
3655   /* Locate the table in question */
3656   pTab = sqlite3FindTable(db, zTableName, zDbName);
3657   if( !pTab || pTab->pSelect ){
3658     pTab = 0;
3659     goto error_out;
3660   }
3661 
3662   /* Find the column for which info is requested */
3663   if( zColumnName==0 ){
3664     /* Query for existance of table only */
3665   }else{
3666     for(iCol=0; iCol<pTab->nCol; iCol++){
3667       pCol = &pTab->aCol[iCol];
3668       if( 0==sqlite3StrICmp(pCol->zName, zColumnName) ){
3669         break;
3670       }
3671     }
3672     if( iCol==pTab->nCol ){
3673       if( HasRowid(pTab) && sqlite3IsRowid(zColumnName) ){
3674         iCol = pTab->iPKey;
3675         pCol = iCol>=0 ? &pTab->aCol[iCol] : 0;
3676       }else{
3677         pTab = 0;
3678         goto error_out;
3679       }
3680     }
3681   }
3682 
3683   /* The following block stores the meta information that will be returned
3684   ** to the caller in local variables zDataType, zCollSeq, notnull, primarykey
3685   ** and autoinc. At this point there are two possibilities:
3686   **
3687   **     1. The specified column name was rowid", "oid" or "_rowid_"
3688   **        and there is no explicitly declared IPK column.
3689   **
3690   **     2. The table is not a view and the column name identified an
3691   **        explicitly declared column. Copy meta information from *pCol.
3692   */
3693   if( pCol ){
3694     zDataType = sqlite3ColumnType(pCol,0);
3695     zCollSeq = pCol->zColl;
3696     notnull = pCol->notNull!=0;
3697     primarykey  = (pCol->colFlags & COLFLAG_PRIMKEY)!=0;
3698     autoinc = pTab->iPKey==iCol && (pTab->tabFlags & TF_Autoincrement)!=0;
3699   }else{
3700     zDataType = "INTEGER";
3701     primarykey = 1;
3702   }
3703   if( !zCollSeq ){
3704     zCollSeq = sqlite3StrBINARY;
3705   }
3706 
3707 error_out:
3708   sqlite3BtreeLeaveAll(db);
3709 
3710   /* Whether the function call succeeded or failed, set the output parameters
3711   ** to whatever their local counterparts contain. If an error did occur,
3712   ** this has the effect of zeroing all output parameters.
3713   */
3714   if( pzDataType ) *pzDataType = zDataType;
3715   if( pzCollSeq ) *pzCollSeq = zCollSeq;
3716   if( pNotNull ) *pNotNull = notnull;
3717   if( pPrimaryKey ) *pPrimaryKey = primarykey;
3718   if( pAutoinc ) *pAutoinc = autoinc;
3719 
3720   if( SQLITE_OK==rc && !pTab ){
3721     sqlite3DbFree(db, zErrMsg);
3722     zErrMsg = sqlite3MPrintf(db, "no such table column: %s.%s", zTableName,
3723         zColumnName);
3724     rc = SQLITE_ERROR;
3725   }
3726   sqlite3ErrorWithMsg(db, rc, (zErrMsg?"%s":0), zErrMsg);
3727   sqlite3DbFree(db, zErrMsg);
3728   rc = sqlite3ApiExit(db, rc);
3729   sqlite3_mutex_leave(db->mutex);
3730   return rc;
3731 }
3732 
3733 /*
3734 ** Sleep for a little while.  Return the amount of time slept.
3735 */
3736 int sqlite3_sleep(int ms){
3737   sqlite3_vfs *pVfs;
3738   int rc;
3739   pVfs = sqlite3_vfs_find(0);
3740   if( pVfs==0 ) return 0;
3741 
3742   /* This function works in milliseconds, but the underlying OsSleep()
3743   ** API uses microseconds. Hence the 1000's.
3744   */
3745   rc = (sqlite3OsSleep(pVfs, 1000*ms)/1000);
3746   return rc;
3747 }
3748 
3749 /*
3750 ** Enable or disable the extended result codes.
3751 */
3752 int sqlite3_extended_result_codes(sqlite3 *db, int onoff){
3753 #ifdef SQLITE_ENABLE_API_ARMOR
3754   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3755 #endif
3756   sqlite3_mutex_enter(db->mutex);
3757   db->errMask = onoff ? 0xffffffff : 0xff;
3758   sqlite3_mutex_leave(db->mutex);
3759   return SQLITE_OK;
3760 }
3761 
3762 /*
3763 ** Invoke the xFileControl method on a particular database.
3764 */
3765 int sqlite3_file_control(sqlite3 *db, const char *zDbName, int op, void *pArg){
3766   int rc = SQLITE_ERROR;
3767   Btree *pBtree;
3768 
3769 #ifdef SQLITE_ENABLE_API_ARMOR
3770   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3771 #endif
3772   sqlite3_mutex_enter(db->mutex);
3773   pBtree = sqlite3DbNameToBtree(db, zDbName);
3774   if( pBtree ){
3775     Pager *pPager;
3776     sqlite3_file *fd;
3777     sqlite3BtreeEnter(pBtree);
3778     pPager = sqlite3BtreePager(pBtree);
3779     assert( pPager!=0 );
3780     fd = sqlite3PagerFile(pPager);
3781     assert( fd!=0 );
3782     if( op==SQLITE_FCNTL_FILE_POINTER ){
3783       *(sqlite3_file**)pArg = fd;
3784       rc = SQLITE_OK;
3785     }else if( op==SQLITE_FCNTL_VFS_POINTER ){
3786       *(sqlite3_vfs**)pArg = sqlite3PagerVfs(pPager);
3787       rc = SQLITE_OK;
3788     }else if( op==SQLITE_FCNTL_JOURNAL_POINTER ){
3789       *(sqlite3_file**)pArg = sqlite3PagerJrnlFile(pPager);
3790       rc = SQLITE_OK;
3791     }else if( op==SQLITE_FCNTL_DATA_VERSION ){
3792       *(unsigned int*)pArg = sqlite3PagerDataVersion(pPager);
3793       rc = SQLITE_OK;
3794     }else{
3795       rc = sqlite3OsFileControl(fd, op, pArg);
3796     }
3797     sqlite3BtreeLeave(pBtree);
3798   }
3799   sqlite3_mutex_leave(db->mutex);
3800   return rc;
3801 }
3802 
3803 /*
3804 ** Interface to the testing logic.
3805 */
3806 int sqlite3_test_control(int op, ...){
3807   int rc = 0;
3808 #ifdef SQLITE_UNTESTABLE
3809   UNUSED_PARAMETER(op);
3810 #else
3811   va_list ap;
3812   va_start(ap, op);
3813   switch( op ){
3814 
3815     /*
3816     ** Save the current state of the PRNG.
3817     */
3818     case SQLITE_TESTCTRL_PRNG_SAVE: {
3819       sqlite3PrngSaveState();
3820       break;
3821     }
3822 
3823     /*
3824     ** Restore the state of the PRNG to the last state saved using
3825     ** PRNG_SAVE.  If PRNG_SAVE has never before been called, then
3826     ** this verb acts like PRNG_RESET.
3827     */
3828     case SQLITE_TESTCTRL_PRNG_RESTORE: {
3829       sqlite3PrngRestoreState();
3830       break;
3831     }
3832 
3833     /*  sqlite3_test_control(SQLITE_TESTCTRL_PRNG_SEED, int x, sqlite3 *db);
3834     **
3835     ** Control the seed for the pseudo-random number generator (PRNG) that
3836     ** is built into SQLite.  Cases:
3837     **
3838     **    x!=0 && db!=0       Seed the PRNG to the current value of the
3839     **                        schema cookie in the main database for db, or
3840     **                        x if the schema cookie is zero.  This case
3841     **                        is convenient to use with database fuzzers
3842     **                        as it allows the fuzzer some control over the
3843     **                        the PRNG seed.
3844     **
3845     **    x!=0 && db==0       Seed the PRNG to the value of x.
3846     **
3847     **    x==0 && db==0       Revert to default behavior of using the
3848     **                        xRandomness method on the primary VFS.
3849     **
3850     ** This test-control also resets the PRNG so that the new seed will
3851     ** be used for the next call to sqlite3_randomness().
3852     */
3853     case SQLITE_TESTCTRL_PRNG_SEED: {
3854       int x = va_arg(ap, int);
3855       int y;
3856       sqlite3 *db = va_arg(ap, sqlite3*);
3857       assert( db==0 || db->aDb[0].pSchema!=0 );
3858       if( db && (y = db->aDb[0].pSchema->schema_cookie)!=0 ){ x = y; }
3859       sqlite3Config.iPrngSeed = x;
3860       sqlite3_randomness(0,0);
3861       break;
3862     }
3863 
3864     /*
3865     **  sqlite3_test_control(BITVEC_TEST, size, program)
3866     **
3867     ** Run a test against a Bitvec object of size.  The program argument
3868     ** is an array of integers that defines the test.  Return -1 on a
3869     ** memory allocation error, 0 on success, or non-zero for an error.
3870     ** See the sqlite3BitvecBuiltinTest() for additional information.
3871     */
3872     case SQLITE_TESTCTRL_BITVEC_TEST: {
3873       int sz = va_arg(ap, int);
3874       int *aProg = va_arg(ap, int*);
3875       rc = sqlite3BitvecBuiltinTest(sz, aProg);
3876       break;
3877     }
3878 
3879     /*
3880     **  sqlite3_test_control(FAULT_INSTALL, xCallback)
3881     **
3882     ** Arrange to invoke xCallback() whenever sqlite3FaultSim() is called,
3883     ** if xCallback is not NULL.
3884     **
3885     ** As a test of the fault simulator mechanism itself, sqlite3FaultSim(0)
3886     ** is called immediately after installing the new callback and the return
3887     ** value from sqlite3FaultSim(0) becomes the return from
3888     ** sqlite3_test_control().
3889     */
3890     case SQLITE_TESTCTRL_FAULT_INSTALL: {
3891       /* MSVC is picky about pulling func ptrs from va lists.
3892       ** http://support.microsoft.com/kb/47961
3893       ** sqlite3GlobalConfig.xTestCallback = va_arg(ap, int(*)(int));
3894       */
3895       typedef int(*TESTCALLBACKFUNC_t)(int);
3896       sqlite3GlobalConfig.xTestCallback = va_arg(ap, TESTCALLBACKFUNC_t);
3897       rc = sqlite3FaultSim(0);
3898       break;
3899     }
3900 
3901     /*
3902     **  sqlite3_test_control(BENIGN_MALLOC_HOOKS, xBegin, xEnd)
3903     **
3904     ** Register hooks to call to indicate which malloc() failures
3905     ** are benign.
3906     */
3907     case SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS: {
3908       typedef void (*void_function)(void);
3909       void_function xBenignBegin;
3910       void_function xBenignEnd;
3911       xBenignBegin = va_arg(ap, void_function);
3912       xBenignEnd = va_arg(ap, void_function);
3913       sqlite3BenignMallocHooks(xBenignBegin, xBenignEnd);
3914       break;
3915     }
3916 
3917     /*
3918     **  sqlite3_test_control(SQLITE_TESTCTRL_PENDING_BYTE, unsigned int X)
3919     **
3920     ** Set the PENDING byte to the value in the argument, if X>0.
3921     ** Make no changes if X==0.  Return the value of the pending byte
3922     ** as it existing before this routine was called.
3923     **
3924     ** IMPORTANT:  Changing the PENDING byte from 0x40000000 results in
3925     ** an incompatible database file format.  Changing the PENDING byte
3926     ** while any database connection is open results in undefined and
3927     ** deleterious behavior.
3928     */
3929     case SQLITE_TESTCTRL_PENDING_BYTE: {
3930       rc = PENDING_BYTE;
3931 #ifndef SQLITE_OMIT_WSD
3932       {
3933         unsigned int newVal = va_arg(ap, unsigned int);
3934         if( newVal ) sqlite3PendingByte = newVal;
3935       }
3936 #endif
3937       break;
3938     }
3939 
3940     /*
3941     **  sqlite3_test_control(SQLITE_TESTCTRL_ASSERT, int X)
3942     **
3943     ** This action provides a run-time test to see whether or not
3944     ** assert() was enabled at compile-time.  If X is true and assert()
3945     ** is enabled, then the return value is true.  If X is true and
3946     ** assert() is disabled, then the return value is zero.  If X is
3947     ** false and assert() is enabled, then the assertion fires and the
3948     ** process aborts.  If X is false and assert() is disabled, then the
3949     ** return value is zero.
3950     */
3951     case SQLITE_TESTCTRL_ASSERT: {
3952       volatile int x = 0;
3953       assert( /*side-effects-ok*/ (x = va_arg(ap,int))!=0 );
3954       rc = x;
3955       break;
3956     }
3957 
3958 
3959     /*
3960     **  sqlite3_test_control(SQLITE_TESTCTRL_ALWAYS, int X)
3961     **
3962     ** This action provides a run-time test to see how the ALWAYS and
3963     ** NEVER macros were defined at compile-time.
3964     **
3965     ** The return value is ALWAYS(X) if X is true, or 0 if X is false.
3966     **
3967     ** The recommended test is X==2.  If the return value is 2, that means
3968     ** ALWAYS() and NEVER() are both no-op pass-through macros, which is the
3969     ** default setting.  If the return value is 1, then ALWAYS() is either
3970     ** hard-coded to true or else it asserts if its argument is false.
3971     ** The first behavior (hard-coded to true) is the case if
3972     ** SQLITE_TESTCTRL_ASSERT shows that assert() is disabled and the second
3973     ** behavior (assert if the argument to ALWAYS() is false) is the case if
3974     ** SQLITE_TESTCTRL_ASSERT shows that assert() is enabled.
3975     **
3976     ** The run-time test procedure might look something like this:
3977     **
3978     **    if( sqlite3_test_control(SQLITE_TESTCTRL_ALWAYS, 2)==2 ){
3979     **      // ALWAYS() and NEVER() are no-op pass-through macros
3980     **    }else if( sqlite3_test_control(SQLITE_TESTCTRL_ASSERT, 1) ){
3981     **      // ALWAYS(x) asserts that x is true. NEVER(x) asserts x is false.
3982     **    }else{
3983     **      // ALWAYS(x) is a constant 1.  NEVER(x) is a constant 0.
3984     **    }
3985     */
3986     case SQLITE_TESTCTRL_ALWAYS: {
3987       int x = va_arg(ap,int);
3988       rc = x ? ALWAYS(x) : 0;
3989       break;
3990     }
3991 
3992     /*
3993     **   sqlite3_test_control(SQLITE_TESTCTRL_BYTEORDER);
3994     **
3995     ** The integer returned reveals the byte-order of the computer on which
3996     ** SQLite is running:
3997     **
3998     **       1     big-endian,    determined at run-time
3999     **      10     little-endian, determined at run-time
4000     **  432101     big-endian,    determined at compile-time
4001     **  123410     little-endian, determined at compile-time
4002     */
4003     case SQLITE_TESTCTRL_BYTEORDER: {
4004       rc = SQLITE_BYTEORDER*100 + SQLITE_LITTLEENDIAN*10 + SQLITE_BIGENDIAN;
4005       break;
4006     }
4007 
4008     /*   sqlite3_test_control(SQLITE_TESTCTRL_RESERVE, sqlite3 *db, int N)
4009     **
4010     ** Set the nReserve size to N for the main database on the database
4011     ** connection db.
4012     */
4013     case SQLITE_TESTCTRL_RESERVE: {
4014       sqlite3 *db = va_arg(ap, sqlite3*);
4015       int x = va_arg(ap,int);
4016       sqlite3_mutex_enter(db->mutex);
4017       sqlite3BtreeSetPageSize(db->aDb[0].pBt, 0, x, 0);
4018       sqlite3_mutex_leave(db->mutex);
4019       break;
4020     }
4021 
4022     /*  sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS, sqlite3 *db, int N)
4023     **
4024     ** Enable or disable various optimizations for testing purposes.  The
4025     ** argument N is a bitmask of optimizations to be disabled.  For normal
4026     ** operation N should be 0.  The idea is that a test program (like the
4027     ** SQL Logic Test or SLT test module) can run the same SQL multiple times
4028     ** with various optimizations disabled to verify that the same answer
4029     ** is obtained in every case.
4030     */
4031     case SQLITE_TESTCTRL_OPTIMIZATIONS: {
4032       sqlite3 *db = va_arg(ap, sqlite3*);
4033       db->dbOptFlags = (u16)(va_arg(ap, int) & 0xffff);
4034       break;
4035     }
4036 
4037     /*   sqlite3_test_control(SQLITE_TESTCTRL_LOCALTIME_FAULT, int onoff);
4038     **
4039     ** If parameter onoff is non-zero, subsequent calls to localtime()
4040     ** and its variants fail. If onoff is zero, undo this setting.
4041     */
4042     case SQLITE_TESTCTRL_LOCALTIME_FAULT: {
4043       sqlite3GlobalConfig.bLocaltimeFault = va_arg(ap, int);
4044       break;
4045     }
4046 
4047     /*   sqlite3_test_control(SQLITE_TESTCTRL_INTERNAL_FUNCS, int onoff);
4048     **
4049     ** If parameter onoff is non-zero, internal-use-only SQL functions
4050     ** are visible to ordinary SQL.  This is useful for testing but is
4051     ** unsafe because invalid parameters to those internal-use-only functions
4052     ** can result in crashes or segfaults.
4053     */
4054     case SQLITE_TESTCTRL_INTERNAL_FUNCTIONS: {
4055       sqlite3GlobalConfig.bInternalFunctions = va_arg(ap, int);
4056       break;
4057     }
4058 
4059     /*   sqlite3_test_control(SQLITE_TESTCTRL_NEVER_CORRUPT, int);
4060     **
4061     ** Set or clear a flag that indicates that the database file is always well-
4062     ** formed and never corrupt.  This flag is clear by default, indicating that
4063     ** database files might have arbitrary corruption.  Setting the flag during
4064     ** testing causes certain assert() statements in the code to be activated
4065     ** that demonstrat invariants on well-formed database files.
4066     */
4067     case SQLITE_TESTCTRL_NEVER_CORRUPT: {
4068       sqlite3GlobalConfig.neverCorrupt = va_arg(ap, int);
4069       break;
4070     }
4071 
4072     /*   sqlite3_test_control(SQLITE_TESTCTRL_EXTRA_SCHEMA_CHECKS, int);
4073     **
4074     ** Set or clear a flag that causes SQLite to verify that type, name,
4075     ** and tbl_name fields of the sqlite_master table.  This is normally
4076     ** on, but it is sometimes useful to turn it off for testing.
4077     */
4078     case SQLITE_TESTCTRL_EXTRA_SCHEMA_CHECKS: {
4079       sqlite3GlobalConfig.bExtraSchemaChecks = va_arg(ap, int);
4080       break;
4081     }
4082 
4083     /* Set the threshold at which OP_Once counters reset back to zero.
4084     ** By default this is 0x7ffffffe (over 2 billion), but that value is
4085     ** too big to test in a reasonable amount of time, so this control is
4086     ** provided to set a small and easily reachable reset value.
4087     */
4088     case SQLITE_TESTCTRL_ONCE_RESET_THRESHOLD: {
4089       sqlite3GlobalConfig.iOnceResetThreshold = va_arg(ap, int);
4090       break;
4091     }
4092 
4093     /*   sqlite3_test_control(SQLITE_TESTCTRL_VDBE_COVERAGE, xCallback, ptr);
4094     **
4095     ** Set the VDBE coverage callback function to xCallback with context
4096     ** pointer ptr.
4097     */
4098     case SQLITE_TESTCTRL_VDBE_COVERAGE: {
4099 #ifdef SQLITE_VDBE_COVERAGE
4100       typedef void (*branch_callback)(void*,unsigned int,
4101                                       unsigned char,unsigned char);
4102       sqlite3GlobalConfig.xVdbeBranch = va_arg(ap,branch_callback);
4103       sqlite3GlobalConfig.pVdbeBranchArg = va_arg(ap,void*);
4104 #endif
4105       break;
4106     }
4107 
4108     /*   sqlite3_test_control(SQLITE_TESTCTRL_SORTER_MMAP, db, nMax); */
4109     case SQLITE_TESTCTRL_SORTER_MMAP: {
4110       sqlite3 *db = va_arg(ap, sqlite3*);
4111       db->nMaxSorterMmap = va_arg(ap, int);
4112       break;
4113     }
4114 
4115     /*   sqlite3_test_control(SQLITE_TESTCTRL_ISINIT);
4116     **
4117     ** Return SQLITE_OK if SQLite has been initialized and SQLITE_ERROR if
4118     ** not.
4119     */
4120     case SQLITE_TESTCTRL_ISINIT: {
4121       if( sqlite3GlobalConfig.isInit==0 ) rc = SQLITE_ERROR;
4122       break;
4123     }
4124 
4125     /*  sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, db, dbName, onOff, tnum);
4126     **
4127     ** This test control is used to create imposter tables.  "db" is a pointer
4128     ** to the database connection.  dbName is the database name (ex: "main" or
4129     ** "temp") which will receive the imposter.  "onOff" turns imposter mode on
4130     ** or off.  "tnum" is the root page of the b-tree to which the imposter
4131     ** table should connect.
4132     **
4133     ** Enable imposter mode only when the schema has already been parsed.  Then
4134     ** run a single CREATE TABLE statement to construct the imposter table in
4135     ** the parsed schema.  Then turn imposter mode back off again.
4136     **
4137     ** If onOff==0 and tnum>0 then reset the schema for all databases, causing
4138     ** the schema to be reparsed the next time it is needed.  This has the
4139     ** effect of erasing all imposter tables.
4140     */
4141     case SQLITE_TESTCTRL_IMPOSTER: {
4142       sqlite3 *db = va_arg(ap, sqlite3*);
4143       sqlite3_mutex_enter(db->mutex);
4144       db->init.iDb = sqlite3FindDbName(db, va_arg(ap,const char*));
4145       db->init.busy = db->init.imposterTable = va_arg(ap,int);
4146       db->init.newTnum = va_arg(ap,int);
4147       if( db->init.busy==0 && db->init.newTnum>0 ){
4148         sqlite3ResetAllSchemasOfConnection(db);
4149       }
4150       sqlite3_mutex_leave(db->mutex);
4151       break;
4152     }
4153 
4154 #if defined(YYCOVERAGE)
4155     /*  sqlite3_test_control(SQLITE_TESTCTRL_PARSER_COVERAGE, FILE *out)
4156     **
4157     ** This test control (only available when SQLite is compiled with
4158     ** -DYYCOVERAGE) writes a report onto "out" that shows all
4159     ** state/lookahead combinations in the parser state machine
4160     ** which are never exercised.  If any state is missed, make the
4161     ** return code SQLITE_ERROR.
4162     */
4163     case SQLITE_TESTCTRL_PARSER_COVERAGE: {
4164       FILE *out = va_arg(ap, FILE*);
4165       if( sqlite3ParserCoverage(out) ) rc = SQLITE_ERROR;
4166       break;
4167     }
4168 #endif /* defined(YYCOVERAGE) */
4169 
4170     /*  sqlite3_test_control(SQLITE_TESTCTRL_RESULT_INTREAL, sqlite3_context*);
4171     **
4172     ** This test-control causes the most recent sqlite3_result_int64() value
4173     ** to be interpreted as a MEM_IntReal instead of as an MEM_Int.  Normally,
4174     ** MEM_IntReal values only arise during an INSERT operation of integer
4175     ** values into a REAL column, so they can be challenging to test.  This
4176     ** test-control enables us to write an intreal() SQL function that can
4177     ** inject an intreal() value at arbitrary places in an SQL statement,
4178     ** for testing purposes.
4179     */
4180     case SQLITE_TESTCTRL_RESULT_INTREAL: {
4181       sqlite3_context *pCtx = va_arg(ap, sqlite3_context*);
4182       sqlite3ResultIntReal(pCtx);
4183       break;
4184     }
4185   }
4186   va_end(ap);
4187 #endif /* SQLITE_UNTESTABLE */
4188   return rc;
4189 }
4190 
4191 #ifdef SQLITE_DEBUG
4192 /*
4193 ** This routine appears inside assert() statements only.
4194 **
4195 ** Return the number of URI parameters that follow the filename.
4196 */
4197 int sqlite3UriCount(const char *z){
4198   int n = 0;
4199   if( z==0 ) return 0;
4200   z += strlen(z)+1;
4201   while( z[0] ){
4202     z += strlen(z)+1;
4203     z += strlen(z)+1;
4204     n++;
4205   }
4206   return n;
4207 }
4208 #endif /* SQLITE_DEBUG */
4209 
4210 /*
4211 ** This is a utility routine, useful to VFS implementations, that checks
4212 ** to see if a database file was a URI that contained a specific query
4213 ** parameter, and if so obtains the value of the query parameter.
4214 **
4215 ** The zFilename argument is the filename pointer passed into the xOpen()
4216 ** method of a VFS implementation.  The zParam argument is the name of the
4217 ** query parameter we seek.  This routine returns the value of the zParam
4218 ** parameter if it exists.  If the parameter does not exist, this routine
4219 ** returns a NULL pointer.
4220 */
4221 const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam){
4222   if( zFilename==0 || zParam==0 ) return 0;
4223   zFilename += sqlite3Strlen30(zFilename) + 1;
4224   while( zFilename[0] ){
4225     int x = strcmp(zFilename, zParam);
4226     zFilename += sqlite3Strlen30(zFilename) + 1;
4227     if( x==0 ) return zFilename;
4228     zFilename += sqlite3Strlen30(zFilename) + 1;
4229   }
4230   return 0;
4231 }
4232 
4233 /*
4234 ** Return a boolean value for a query parameter.
4235 */
4236 int sqlite3_uri_boolean(const char *zFilename, const char *zParam, int bDflt){
4237   const char *z = sqlite3_uri_parameter(zFilename, zParam);
4238   bDflt = bDflt!=0;
4239   return z ? sqlite3GetBoolean(z, bDflt) : bDflt;
4240 }
4241 
4242 /*
4243 ** Return a 64-bit integer value for a query parameter.
4244 */
4245 sqlite3_int64 sqlite3_uri_int64(
4246   const char *zFilename,    /* Filename as passed to xOpen */
4247   const char *zParam,       /* URI parameter sought */
4248   sqlite3_int64 bDflt       /* return if parameter is missing */
4249 ){
4250   const char *z = sqlite3_uri_parameter(zFilename, zParam);
4251   sqlite3_int64 v;
4252   if( z && sqlite3DecOrHexToI64(z, &v)==0 ){
4253     bDflt = v;
4254   }
4255   return bDflt;
4256 }
4257 
4258 /*
4259 ** Return the Btree pointer identified by zDbName.  Return NULL if not found.
4260 */
4261 Btree *sqlite3DbNameToBtree(sqlite3 *db, const char *zDbName){
4262   int iDb = zDbName ? sqlite3FindDbName(db, zDbName) : 0;
4263   return iDb<0 ? 0 : db->aDb[iDb].pBt;
4264 }
4265 
4266 /*
4267 ** Return the filename of the database associated with a database
4268 ** connection.
4269 */
4270 const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName){
4271   Btree *pBt;
4272 #ifdef SQLITE_ENABLE_API_ARMOR
4273   if( !sqlite3SafetyCheckOk(db) ){
4274     (void)SQLITE_MISUSE_BKPT;
4275     return 0;
4276   }
4277 #endif
4278   pBt = sqlite3DbNameToBtree(db, zDbName);
4279   return pBt ? sqlite3BtreeGetFilename(pBt) : 0;
4280 }
4281 
4282 /*
4283 ** Return 1 if database is read-only or 0 if read/write.  Return -1 if
4284 ** no such database exists.
4285 */
4286 int sqlite3_db_readonly(sqlite3 *db, const char *zDbName){
4287   Btree *pBt;
4288 #ifdef SQLITE_ENABLE_API_ARMOR
4289   if( !sqlite3SafetyCheckOk(db) ){
4290     (void)SQLITE_MISUSE_BKPT;
4291     return -1;
4292   }
4293 #endif
4294   pBt = sqlite3DbNameToBtree(db, zDbName);
4295   return pBt ? sqlite3BtreeIsReadonly(pBt) : -1;
4296 }
4297 
4298 #ifdef SQLITE_ENABLE_SNAPSHOT
4299 /*
4300 ** Obtain a snapshot handle for the snapshot of database zDb currently
4301 ** being read by handle db.
4302 */
4303 int sqlite3_snapshot_get(
4304   sqlite3 *db,
4305   const char *zDb,
4306   sqlite3_snapshot **ppSnapshot
4307 ){
4308   int rc = SQLITE_ERROR;
4309 #ifndef SQLITE_OMIT_WAL
4310 
4311 #ifdef SQLITE_ENABLE_API_ARMOR
4312   if( !sqlite3SafetyCheckOk(db) ){
4313     return SQLITE_MISUSE_BKPT;
4314   }
4315 #endif
4316   sqlite3_mutex_enter(db->mutex);
4317 
4318   if( db->autoCommit==0 ){
4319     int iDb = sqlite3FindDbName(db, zDb);
4320     if( iDb==0 || iDb>1 ){
4321       Btree *pBt = db->aDb[iDb].pBt;
4322       if( 0==sqlite3BtreeIsInTrans(pBt) ){
4323         rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
4324         if( rc==SQLITE_OK ){
4325           rc = sqlite3PagerSnapshotGet(sqlite3BtreePager(pBt), ppSnapshot);
4326         }
4327       }
4328     }
4329   }
4330 
4331   sqlite3_mutex_leave(db->mutex);
4332 #endif   /* SQLITE_OMIT_WAL */
4333   return rc;
4334 }
4335 
4336 /*
4337 ** Open a read-transaction on the snapshot idendified by pSnapshot.
4338 */
4339 int sqlite3_snapshot_open(
4340   sqlite3 *db,
4341   const char *zDb,
4342   sqlite3_snapshot *pSnapshot
4343 ){
4344   int rc = SQLITE_ERROR;
4345 #ifndef SQLITE_OMIT_WAL
4346 
4347 #ifdef SQLITE_ENABLE_API_ARMOR
4348   if( !sqlite3SafetyCheckOk(db) ){
4349     return SQLITE_MISUSE_BKPT;
4350   }
4351 #endif
4352   sqlite3_mutex_enter(db->mutex);
4353   if( db->autoCommit==0 ){
4354     int iDb;
4355     iDb = sqlite3FindDbName(db, zDb);
4356     if( iDb==0 || iDb>1 ){
4357       Btree *pBt = db->aDb[iDb].pBt;
4358       if( sqlite3BtreeIsInTrans(pBt)==0 ){
4359         Pager *pPager = sqlite3BtreePager(pBt);
4360         int bUnlock = 0;
4361         if( sqlite3BtreeIsInReadTrans(pBt) ){
4362           if( db->nVdbeActive==0 ){
4363             rc = sqlite3PagerSnapshotCheck(pPager, pSnapshot);
4364             if( rc==SQLITE_OK ){
4365               bUnlock = 1;
4366               rc = sqlite3BtreeCommit(pBt);
4367             }
4368           }
4369         }else{
4370           rc = SQLITE_OK;
4371         }
4372         if( rc==SQLITE_OK ){
4373           rc = sqlite3PagerSnapshotOpen(pPager, pSnapshot);
4374         }
4375         if( rc==SQLITE_OK ){
4376           rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
4377           sqlite3PagerSnapshotOpen(pPager, 0);
4378         }
4379         if( bUnlock ){
4380           sqlite3PagerSnapshotUnlock(pPager);
4381         }
4382       }
4383     }
4384   }
4385 
4386   sqlite3_mutex_leave(db->mutex);
4387 #endif   /* SQLITE_OMIT_WAL */
4388   return rc;
4389 }
4390 
4391 /*
4392 ** Recover as many snapshots as possible from the wal file associated with
4393 ** schema zDb of database db.
4394 */
4395 int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb){
4396   int rc = SQLITE_ERROR;
4397   int iDb;
4398 #ifndef SQLITE_OMIT_WAL
4399 
4400 #ifdef SQLITE_ENABLE_API_ARMOR
4401   if( !sqlite3SafetyCheckOk(db) ){
4402     return SQLITE_MISUSE_BKPT;
4403   }
4404 #endif
4405 
4406   sqlite3_mutex_enter(db->mutex);
4407   iDb = sqlite3FindDbName(db, zDb);
4408   if( iDb==0 || iDb>1 ){
4409     Btree *pBt = db->aDb[iDb].pBt;
4410     if( 0==sqlite3BtreeIsInReadTrans(pBt) ){
4411       rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
4412       if( rc==SQLITE_OK ){
4413         rc = sqlite3PagerSnapshotRecover(sqlite3BtreePager(pBt));
4414         sqlite3BtreeCommit(pBt);
4415       }
4416     }
4417   }
4418   sqlite3_mutex_leave(db->mutex);
4419 #endif   /* SQLITE_OMIT_WAL */
4420   return rc;
4421 }
4422 
4423 /*
4424 ** Free a snapshot handle obtained from sqlite3_snapshot_get().
4425 */
4426 void sqlite3_snapshot_free(sqlite3_snapshot *pSnapshot){
4427   sqlite3_free(pSnapshot);
4428 }
4429 #endif /* SQLITE_ENABLE_SNAPSHOT */
4430 
4431 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
4432 /*
4433 ** Given the name of a compile-time option, return true if that option
4434 ** was used and false if not.
4435 **
4436 ** The name can optionally begin with "SQLITE_" but the "SQLITE_" prefix
4437 ** is not required for a match.
4438 */
4439 int sqlite3_compileoption_used(const char *zOptName){
4440   int i, n;
4441   int nOpt;
4442   const char **azCompileOpt;
4443 
4444 #if SQLITE_ENABLE_API_ARMOR
4445   if( zOptName==0 ){
4446     (void)SQLITE_MISUSE_BKPT;
4447     return 0;
4448   }
4449 #endif
4450 
4451   azCompileOpt = sqlite3CompileOptions(&nOpt);
4452 
4453   if( sqlite3StrNICmp(zOptName, "SQLITE_", 7)==0 ) zOptName += 7;
4454   n = sqlite3Strlen30(zOptName);
4455 
4456   /* Since nOpt is normally in single digits, a linear search is
4457   ** adequate. No need for a binary search. */
4458   for(i=0; i<nOpt; i++){
4459     if( sqlite3StrNICmp(zOptName, azCompileOpt[i], n)==0
4460      && sqlite3IsIdChar((unsigned char)azCompileOpt[i][n])==0
4461     ){
4462       return 1;
4463     }
4464   }
4465   return 0;
4466 }
4467 
4468 /*
4469 ** Return the N-th compile-time option string.  If N is out of range,
4470 ** return a NULL pointer.
4471 */
4472 const char *sqlite3_compileoption_get(int N){
4473   int nOpt;
4474   const char **azCompileOpt;
4475   azCompileOpt = sqlite3CompileOptions(&nOpt);
4476   if( N>=0 && N<nOpt ){
4477     return azCompileOpt[N];
4478   }
4479   return 0;
4480 }
4481 #endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
4482