xref: /sqlite-3.40.0/src/main.c (revision 119fc11e)
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 #ifdef SQLITE_ENABLE_ICU
26 # include "sqliteicu.h"
27 #endif
28 #ifdef SQLITE_ENABLE_JSON1
29 int sqlite3Json1Init(sqlite3*);
30 #endif
31 #ifdef SQLITE_ENABLE_FTS5
32 int sqlite3Fts5Init(sqlite3*);
33 #endif
34 
35 #ifndef SQLITE_AMALGAMATION
36 /* IMPLEMENTATION-OF: R-46656-45156 The sqlite3_version[] string constant
37 ** contains the text of SQLITE_VERSION macro.
38 */
39 const char sqlite3_version[] = SQLITE_VERSION;
40 #endif
41 
42 /* IMPLEMENTATION-OF: R-53536-42575 The sqlite3_libversion() function returns
43 ** a pointer to the to the sqlite3_version[] string constant.
44 */
45 const char *sqlite3_libversion(void){ return sqlite3_version; }
46 
47 /* IMPLEMENTATION-OF: R-63124-39300 The sqlite3_sourceid() function returns a
48 ** pointer to a string constant whose value is the same as the
49 ** SQLITE_SOURCE_ID C preprocessor macro.
50 */
51 const char *sqlite3_sourceid(void){ return SQLITE_SOURCE_ID; }
52 
53 /* IMPLEMENTATION-OF: R-35210-63508 The sqlite3_libversion_number() function
54 ** returns an integer equal to SQLITE_VERSION_NUMBER.
55 */
56 int sqlite3_libversion_number(void){ return SQLITE_VERSION_NUMBER; }
57 
58 /* IMPLEMENTATION-OF: R-20790-14025 The sqlite3_threadsafe() function returns
59 ** zero if and only if SQLite was compiled with mutexing code omitted due to
60 ** the SQLITE_THREADSAFE compile-time option being set to 0.
61 */
62 int sqlite3_threadsafe(void){ return SQLITE_THREADSAFE; }
63 
64 /*
65 ** When compiling the test fixture or with debugging enabled (on Win32),
66 ** this variable being set to non-zero will cause OSTRACE macros to emit
67 ** extra diagnostic information.
68 */
69 #ifdef SQLITE_HAVE_OS_TRACE
70 # ifndef SQLITE_DEBUG_OS_TRACE
71 #   define SQLITE_DEBUG_OS_TRACE 0
72 # endif
73   int sqlite3OSTrace = SQLITE_DEBUG_OS_TRACE;
74 #endif
75 
76 #if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
77 /*
78 ** If the following function pointer is not NULL and if
79 ** SQLITE_ENABLE_IOTRACE is enabled, then messages describing
80 ** I/O active are written using this function.  These messages
81 ** are intended for debugging activity only.
82 */
83 SQLITE_API void (SQLITE_CDECL *sqlite3IoTrace)(const char*, ...) = 0;
84 #endif
85 
86 /*
87 ** If the following global variable points to a string which is the
88 ** name of a directory, then that directory will be used to store
89 ** temporary files.
90 **
91 ** See also the "PRAGMA temp_store_directory" SQL command.
92 */
93 char *sqlite3_temp_directory = 0;
94 
95 /*
96 ** If the following global variable points to a string which is the
97 ** name of a directory, then that directory will be used to store
98 ** all database files specified with a relative pathname.
99 **
100 ** See also the "PRAGMA data_store_directory" SQL command.
101 */
102 char *sqlite3_data_directory = 0;
103 
104 /*
105 ** Initialize SQLite.
106 **
107 ** This routine must be called to initialize the memory allocation,
108 ** VFS, and mutex subsystems prior to doing any serious work with
109 ** SQLite.  But as long as you do not compile with SQLITE_OMIT_AUTOINIT
110 ** this routine will be called automatically by key routines such as
111 ** sqlite3_open().
112 **
113 ** This routine is a no-op except on its very first call for the process,
114 ** or for the first call after a call to sqlite3_shutdown.
115 **
116 ** The first thread to call this routine runs the initialization to
117 ** completion.  If subsequent threads call this routine before the first
118 ** thread has finished the initialization process, then the subsequent
119 ** threads must block until the first thread finishes with the initialization.
120 **
121 ** The first thread might call this routine recursively.  Recursive
122 ** calls to this routine should not block, of course.  Otherwise the
123 ** initialization process would never complete.
124 **
125 ** Let X be the first thread to enter this routine.  Let Y be some other
126 ** thread.  Then while the initial invocation of this routine by X is
127 ** incomplete, it is required that:
128 **
129 **    *  Calls to this routine from Y must block until the outer-most
130 **       call by X completes.
131 **
132 **    *  Recursive calls to this routine from thread X return immediately
133 **       without blocking.
134 */
135 int sqlite3_initialize(void){
136   MUTEX_LOGIC( sqlite3_mutex *pMaster; )       /* The main static mutex */
137   int rc;                                      /* Result code */
138 #ifdef SQLITE_EXTRA_INIT
139   int bRunExtraInit = 0;                       /* Extra initialization needed */
140 #endif
141 
142 #ifdef SQLITE_OMIT_WSD
143   rc = sqlite3_wsd_init(4096, 24);
144   if( rc!=SQLITE_OK ){
145     return rc;
146   }
147 #endif
148 
149   /* If the following assert() fails on some obscure processor/compiler
150   ** combination, the work-around is to set the correct pointer
151   ** size at compile-time using -DSQLITE_PTRSIZE=n compile-time option */
152   assert( SQLITE_PTRSIZE==sizeof(char*) );
153 
154   /* If SQLite is already completely initialized, then this call
155   ** to sqlite3_initialize() should be a no-op.  But the initialization
156   ** must be complete.  So isInit must not be set until the very end
157   ** of this routine.
158   */
159   if( sqlite3GlobalConfig.isInit ) return SQLITE_OK;
160 
161   /* Make sure the mutex subsystem is initialized.  If unable to
162   ** initialize the mutex subsystem, return early with the error.
163   ** If the system is so sick that we are unable to allocate a mutex,
164   ** there is not much SQLite is going to be able to do.
165   **
166   ** The mutex subsystem must take care of serializing its own
167   ** initialization.
168   */
169   rc = sqlite3MutexInit();
170   if( rc ) return rc;
171 
172   /* Initialize the malloc() system and the recursive pInitMutex mutex.
173   ** This operation is protected by the STATIC_MASTER mutex.  Note that
174   ** MutexAlloc() is called for a static mutex prior to initializing the
175   ** malloc subsystem - this implies that the allocation of a static
176   ** mutex must not require support from the malloc subsystem.
177   */
178   MUTEX_LOGIC( pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
179   sqlite3_mutex_enter(pMaster);
180   sqlite3GlobalConfig.isMutexInit = 1;
181   if( !sqlite3GlobalConfig.isMallocInit ){
182     rc = sqlite3MallocInit();
183   }
184   if( rc==SQLITE_OK ){
185     sqlite3GlobalConfig.isMallocInit = 1;
186     if( !sqlite3GlobalConfig.pInitMutex ){
187       sqlite3GlobalConfig.pInitMutex =
188            sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
189       if( sqlite3GlobalConfig.bCoreMutex && !sqlite3GlobalConfig.pInitMutex ){
190         rc = SQLITE_NOMEM_BKPT;
191       }
192     }
193   }
194   if( rc==SQLITE_OK ){
195     sqlite3GlobalConfig.nRefInitMutex++;
196   }
197   sqlite3_mutex_leave(pMaster);
198 
199   /* If rc is not SQLITE_OK at this point, then either the malloc
200   ** subsystem could not be initialized or the system failed to allocate
201   ** the pInitMutex mutex. Return an error in either case.  */
202   if( rc!=SQLITE_OK ){
203     return rc;
204   }
205 
206   /* Do the rest of the initialization under the recursive mutex so
207   ** that we will be able to handle recursive calls into
208   ** sqlite3_initialize().  The recursive calls normally come through
209   ** sqlite3_os_init() when it invokes sqlite3_vfs_register(), but other
210   ** recursive calls might also be possible.
211   **
212   ** IMPLEMENTATION-OF: R-00140-37445 SQLite automatically serializes calls
213   ** to the xInit method, so the xInit method need not be threadsafe.
214   **
215   ** The following mutex is what serializes access to the appdef pcache xInit
216   ** methods.  The sqlite3_pcache_methods.xInit() all is embedded in the
217   ** call to sqlite3PcacheInitialize().
218   */
219   sqlite3_mutex_enter(sqlite3GlobalConfig.pInitMutex);
220   if( sqlite3GlobalConfig.isInit==0 && sqlite3GlobalConfig.inProgress==0 ){
221     sqlite3GlobalConfig.inProgress = 1;
222 #ifdef SQLITE_ENABLE_SQLLOG
223     {
224       extern void sqlite3_init_sqllog(void);
225       sqlite3_init_sqllog();
226     }
227 #endif
228     memset(&sqlite3BuiltinFunctions, 0, sizeof(sqlite3BuiltinFunctions));
229     sqlite3RegisterBuiltinFunctions();
230     if( sqlite3GlobalConfig.isPCacheInit==0 ){
231       rc = sqlite3PcacheInitialize();
232     }
233     if( rc==SQLITE_OK ){
234       sqlite3GlobalConfig.isPCacheInit = 1;
235       rc = sqlite3OsInit();
236     }
237     if( rc==SQLITE_OK ){
238       sqlite3PCacheBufferSetup( sqlite3GlobalConfig.pPage,
239           sqlite3GlobalConfig.szPage, sqlite3GlobalConfig.nPage);
240       sqlite3GlobalConfig.isInit = 1;
241 #ifdef SQLITE_EXTRA_INIT
242       bRunExtraInit = 1;
243 #endif
244     }
245     sqlite3GlobalConfig.inProgress = 0;
246   }
247   sqlite3_mutex_leave(sqlite3GlobalConfig.pInitMutex);
248 
249   /* Go back under the static mutex and clean up the recursive
250   ** mutex to prevent a resource leak.
251   */
252   sqlite3_mutex_enter(pMaster);
253   sqlite3GlobalConfig.nRefInitMutex--;
254   if( sqlite3GlobalConfig.nRefInitMutex<=0 ){
255     assert( sqlite3GlobalConfig.nRefInitMutex==0 );
256     sqlite3_mutex_free(sqlite3GlobalConfig.pInitMutex);
257     sqlite3GlobalConfig.pInitMutex = 0;
258   }
259   sqlite3_mutex_leave(pMaster);
260 
261   /* The following is just a sanity check to make sure SQLite has
262   ** been compiled correctly.  It is important to run this code, but
263   ** we don't want to run it too often and soak up CPU cycles for no
264   ** reason.  So we run it once during initialization.
265   */
266 #ifndef NDEBUG
267 #ifndef SQLITE_OMIT_FLOATING_POINT
268   /* This section of code's only "output" is via assert() statements. */
269   if ( rc==SQLITE_OK ){
270     u64 x = (((u64)1)<<63)-1;
271     double y;
272     assert(sizeof(x)==8);
273     assert(sizeof(x)==sizeof(y));
274     memcpy(&y, &x, 8);
275     assert( sqlite3IsNaN(y) );
276   }
277 #endif
278 #endif
279 
280   /* Do extra initialization steps requested by the SQLITE_EXTRA_INIT
281   ** compile-time option.
282   */
283 #ifdef SQLITE_EXTRA_INIT
284   if( bRunExtraInit ){
285     int SQLITE_EXTRA_INIT(const char*);
286     rc = SQLITE_EXTRA_INIT(0);
287   }
288 #endif
289 
290   return rc;
291 }
292 
293 /*
294 ** Undo the effects of sqlite3_initialize().  Must not be called while
295 ** there are outstanding database connections or memory allocations or
296 ** while any part of SQLite is otherwise in use in any thread.  This
297 ** routine is not threadsafe.  But it is safe to invoke this routine
298 ** on when SQLite is already shut down.  If SQLite is already shut down
299 ** when this routine is invoked, then this routine is a harmless no-op.
300 */
301 int sqlite3_shutdown(void){
302 #ifdef SQLITE_OMIT_WSD
303   int rc = sqlite3_wsd_init(4096, 24);
304   if( rc!=SQLITE_OK ){
305     return rc;
306   }
307 #endif
308 
309   if( sqlite3GlobalConfig.isInit ){
310 #ifdef SQLITE_EXTRA_SHUTDOWN
311     void SQLITE_EXTRA_SHUTDOWN(void);
312     SQLITE_EXTRA_SHUTDOWN();
313 #endif
314     sqlite3_os_end();
315     sqlite3_reset_auto_extension();
316     sqlite3GlobalConfig.isInit = 0;
317   }
318   if( sqlite3GlobalConfig.isPCacheInit ){
319     sqlite3PcacheShutdown();
320     sqlite3GlobalConfig.isPCacheInit = 0;
321   }
322   if( sqlite3GlobalConfig.isMallocInit ){
323     sqlite3MallocEnd();
324     sqlite3GlobalConfig.isMallocInit = 0;
325 
326 #ifndef SQLITE_OMIT_SHUTDOWN_DIRECTORIES
327     /* The heap subsystem has now been shutdown and these values are supposed
328     ** to be NULL or point to memory that was obtained from sqlite3_malloc(),
329     ** which would rely on that heap subsystem; therefore, make sure these
330     ** values cannot refer to heap memory that was just invalidated when the
331     ** heap subsystem was shutdown.  This is only done if the current call to
332     ** this function resulted in the heap subsystem actually being shutdown.
333     */
334     sqlite3_data_directory = 0;
335     sqlite3_temp_directory = 0;
336 #endif
337   }
338   if( sqlite3GlobalConfig.isMutexInit ){
339     sqlite3MutexEnd();
340     sqlite3GlobalConfig.isMutexInit = 0;
341   }
342 
343   return SQLITE_OK;
344 }
345 
346 /*
347 ** This API allows applications to modify the global configuration of
348 ** the SQLite library at run-time.
349 **
350 ** This routine should only be called when there are no outstanding
351 ** database connections or memory allocations.  This routine is not
352 ** threadsafe.  Failure to heed these warnings can lead to unpredictable
353 ** behavior.
354 */
355 int sqlite3_config(int op, ...){
356   va_list ap;
357   int rc = SQLITE_OK;
358 
359   /* sqlite3_config() shall return SQLITE_MISUSE if it is invoked while
360   ** the SQLite library is in use. */
361   if( sqlite3GlobalConfig.isInit ) return SQLITE_MISUSE_BKPT;
362 
363   va_start(ap, op);
364   switch( op ){
365 
366     /* Mutex configuration options are only available in a threadsafe
367     ** compile.
368     */
369 #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0  /* IMP: R-54466-46756 */
370     case SQLITE_CONFIG_SINGLETHREAD: {
371       /* EVIDENCE-OF: R-02748-19096 This option sets the threading mode to
372       ** Single-thread. */
373       sqlite3GlobalConfig.bCoreMutex = 0;  /* Disable mutex on core */
374       sqlite3GlobalConfig.bFullMutex = 0;  /* Disable mutex on connections */
375       break;
376     }
377 #endif
378 #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-20520-54086 */
379     case SQLITE_CONFIG_MULTITHREAD: {
380       /* EVIDENCE-OF: R-14374-42468 This option sets the threading mode to
381       ** Multi-thread. */
382       sqlite3GlobalConfig.bCoreMutex = 1;  /* Enable mutex on core */
383       sqlite3GlobalConfig.bFullMutex = 0;  /* Disable mutex on connections */
384       break;
385     }
386 #endif
387 #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-59593-21810 */
388     case SQLITE_CONFIG_SERIALIZED: {
389       /* EVIDENCE-OF: R-41220-51800 This option sets the threading mode to
390       ** Serialized. */
391       sqlite3GlobalConfig.bCoreMutex = 1;  /* Enable mutex on core */
392       sqlite3GlobalConfig.bFullMutex = 1;  /* Enable mutex on connections */
393       break;
394     }
395 #endif
396 #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-63666-48755 */
397     case SQLITE_CONFIG_MUTEX: {
398       /* Specify an alternative mutex implementation */
399       sqlite3GlobalConfig.mutex = *va_arg(ap, sqlite3_mutex_methods*);
400       break;
401     }
402 #endif
403 #if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE>0 /* IMP: R-14450-37597 */
404     case SQLITE_CONFIG_GETMUTEX: {
405       /* Retrieve the current mutex implementation */
406       *va_arg(ap, sqlite3_mutex_methods*) = sqlite3GlobalConfig.mutex;
407       break;
408     }
409 #endif
410 
411     case SQLITE_CONFIG_MALLOC: {
412       /* EVIDENCE-OF: R-55594-21030 The SQLITE_CONFIG_MALLOC option takes a
413       ** single argument which is a pointer to an instance of the
414       ** sqlite3_mem_methods structure. The argument specifies alternative
415       ** low-level memory allocation routines to be used in place of the memory
416       ** allocation routines built into SQLite. */
417       sqlite3GlobalConfig.m = *va_arg(ap, sqlite3_mem_methods*);
418       break;
419     }
420     case SQLITE_CONFIG_GETMALLOC: {
421       /* EVIDENCE-OF: R-51213-46414 The SQLITE_CONFIG_GETMALLOC option takes a
422       ** single argument which is a pointer to an instance of the
423       ** sqlite3_mem_methods structure. The sqlite3_mem_methods structure is
424       ** filled with the currently defined memory allocation routines. */
425       if( sqlite3GlobalConfig.m.xMalloc==0 ) sqlite3MemSetDefault();
426       *va_arg(ap, sqlite3_mem_methods*) = sqlite3GlobalConfig.m;
427       break;
428     }
429     case SQLITE_CONFIG_MEMSTATUS: {
430       /* EVIDENCE-OF: R-61275-35157 The SQLITE_CONFIG_MEMSTATUS option takes
431       ** single argument of type int, interpreted as a boolean, which enables
432       ** or disables the collection of memory allocation statistics. */
433       sqlite3GlobalConfig.bMemstat = va_arg(ap, int);
434       break;
435     }
436     case SQLITE_CONFIG_SCRATCH: {
437       /* EVIDENCE-OF: R-08404-60887 There are three arguments to
438       ** SQLITE_CONFIG_SCRATCH: A pointer an 8-byte aligned memory buffer from
439       ** which the scratch allocations will be drawn, the size of each scratch
440       ** allocation (sz), and the maximum number of scratch allocations (N). */
441       sqlite3GlobalConfig.pScratch = va_arg(ap, void*);
442       sqlite3GlobalConfig.szScratch = va_arg(ap, int);
443       sqlite3GlobalConfig.nScratch = va_arg(ap, int);
444       break;
445     }
446     case SQLITE_CONFIG_PAGECACHE: {
447       /* EVIDENCE-OF: R-18761-36601 There are three arguments to
448       ** SQLITE_CONFIG_PAGECACHE: A pointer to 8-byte aligned memory (pMem),
449       ** the size of each page cache line (sz), and the number of cache lines
450       ** (N). */
451       sqlite3GlobalConfig.pPage = va_arg(ap, void*);
452       sqlite3GlobalConfig.szPage = va_arg(ap, int);
453       sqlite3GlobalConfig.nPage = va_arg(ap, int);
454       break;
455     }
456     case SQLITE_CONFIG_PCACHE_HDRSZ: {
457       /* EVIDENCE-OF: R-39100-27317 The SQLITE_CONFIG_PCACHE_HDRSZ option takes
458       ** a single parameter which is a pointer to an integer and writes into
459       ** that integer the number of extra bytes per page required for each page
460       ** in SQLITE_CONFIG_PAGECACHE. */
461       *va_arg(ap, int*) =
462           sqlite3HeaderSizeBtree() +
463           sqlite3HeaderSizePcache() +
464           sqlite3HeaderSizePcache1();
465       break;
466     }
467 
468     case SQLITE_CONFIG_PCACHE: {
469       /* no-op */
470       break;
471     }
472     case SQLITE_CONFIG_GETPCACHE: {
473       /* now an error */
474       rc = SQLITE_ERROR;
475       break;
476     }
477 
478     case SQLITE_CONFIG_PCACHE2: {
479       /* EVIDENCE-OF: R-63325-48378 The SQLITE_CONFIG_PCACHE2 option takes a
480       ** single argument which is a pointer to an sqlite3_pcache_methods2
481       ** object. This object specifies the interface to a custom page cache
482       ** implementation. */
483       sqlite3GlobalConfig.pcache2 = *va_arg(ap, sqlite3_pcache_methods2*);
484       break;
485     }
486     case SQLITE_CONFIG_GETPCACHE2: {
487       /* EVIDENCE-OF: R-22035-46182 The SQLITE_CONFIG_GETPCACHE2 option takes a
488       ** single argument which is a pointer to an sqlite3_pcache_methods2
489       ** object. SQLite copies of the current page cache implementation into
490       ** that object. */
491       if( sqlite3GlobalConfig.pcache2.xInit==0 ){
492         sqlite3PCacheSetDefault();
493       }
494       *va_arg(ap, sqlite3_pcache_methods2*) = sqlite3GlobalConfig.pcache2;
495       break;
496     }
497 
498 /* EVIDENCE-OF: R-06626-12911 The SQLITE_CONFIG_HEAP option is only
499 ** available if SQLite is compiled with either SQLITE_ENABLE_MEMSYS3 or
500 ** SQLITE_ENABLE_MEMSYS5 and returns SQLITE_ERROR if invoked otherwise. */
501 #if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
502     case SQLITE_CONFIG_HEAP: {
503       /* EVIDENCE-OF: R-19854-42126 There are three arguments to
504       ** SQLITE_CONFIG_HEAP: An 8-byte aligned pointer to the memory, the
505       ** number of bytes in the memory buffer, and the minimum allocation size.
506       */
507       sqlite3GlobalConfig.pHeap = va_arg(ap, void*);
508       sqlite3GlobalConfig.nHeap = va_arg(ap, int);
509       sqlite3GlobalConfig.mnReq = va_arg(ap, int);
510 
511       if( sqlite3GlobalConfig.mnReq<1 ){
512         sqlite3GlobalConfig.mnReq = 1;
513       }else if( sqlite3GlobalConfig.mnReq>(1<<12) ){
514         /* cap min request size at 2^12 */
515         sqlite3GlobalConfig.mnReq = (1<<12);
516       }
517 
518       if( sqlite3GlobalConfig.pHeap==0 ){
519         /* EVIDENCE-OF: R-49920-60189 If the first pointer (the memory pointer)
520         ** is NULL, then SQLite reverts to using its default memory allocator
521         ** (the system malloc() implementation), undoing any prior invocation of
522         ** SQLITE_CONFIG_MALLOC.
523         **
524         ** Setting sqlite3GlobalConfig.m to all zeros will cause malloc to
525         ** revert to its default implementation when sqlite3_initialize() is run
526         */
527         memset(&sqlite3GlobalConfig.m, 0, sizeof(sqlite3GlobalConfig.m));
528       }else{
529         /* EVIDENCE-OF: R-61006-08918 If the memory pointer is not NULL then the
530         ** alternative memory allocator is engaged to handle all of SQLites
531         ** memory allocation needs. */
532 #ifdef SQLITE_ENABLE_MEMSYS3
533         sqlite3GlobalConfig.m = *sqlite3MemGetMemsys3();
534 #endif
535 #ifdef SQLITE_ENABLE_MEMSYS5
536         sqlite3GlobalConfig.m = *sqlite3MemGetMemsys5();
537 #endif
538       }
539       break;
540     }
541 #endif
542 
543     case SQLITE_CONFIG_LOOKASIDE: {
544       sqlite3GlobalConfig.szLookaside = va_arg(ap, int);
545       sqlite3GlobalConfig.nLookaside = va_arg(ap, int);
546       break;
547     }
548 
549     /* Record a pointer to the logger function and its first argument.
550     ** The default is NULL.  Logging is disabled if the function pointer is
551     ** NULL.
552     */
553     case SQLITE_CONFIG_LOG: {
554       /* MSVC is picky about pulling func ptrs from va lists.
555       ** http://support.microsoft.com/kb/47961
556       ** sqlite3GlobalConfig.xLog = va_arg(ap, void(*)(void*,int,const char*));
557       */
558       typedef void(*LOGFUNC_t)(void*,int,const char*);
559       sqlite3GlobalConfig.xLog = va_arg(ap, LOGFUNC_t);
560       sqlite3GlobalConfig.pLogArg = va_arg(ap, void*);
561       break;
562     }
563 
564     /* EVIDENCE-OF: R-55548-33817 The compile-time setting for URI filenames
565     ** can be changed at start-time using the
566     ** sqlite3_config(SQLITE_CONFIG_URI,1) or
567     ** sqlite3_config(SQLITE_CONFIG_URI,0) configuration calls.
568     */
569     case SQLITE_CONFIG_URI: {
570       /* EVIDENCE-OF: R-25451-61125 The SQLITE_CONFIG_URI option takes a single
571       ** argument of type int. If non-zero, then URI handling is globally
572       ** enabled. If the parameter is zero, then URI handling is globally
573       ** disabled. */
574       sqlite3GlobalConfig.bOpenUri = va_arg(ap, int);
575       break;
576     }
577 
578     case SQLITE_CONFIG_COVERING_INDEX_SCAN: {
579       /* EVIDENCE-OF: R-36592-02772 The SQLITE_CONFIG_COVERING_INDEX_SCAN
580       ** option takes a single integer argument which is interpreted as a
581       ** boolean in order to enable or disable the use of covering indices for
582       ** full table scans in the query optimizer. */
583       sqlite3GlobalConfig.bUseCis = va_arg(ap, int);
584       break;
585     }
586 
587 #ifdef SQLITE_ENABLE_SQLLOG
588     case SQLITE_CONFIG_SQLLOG: {
589       typedef void(*SQLLOGFUNC_t)(void*, sqlite3*, const char*, int);
590       sqlite3GlobalConfig.xSqllog = va_arg(ap, SQLLOGFUNC_t);
591       sqlite3GlobalConfig.pSqllogArg = va_arg(ap, void *);
592       break;
593     }
594 #endif
595 
596     case SQLITE_CONFIG_MMAP_SIZE: {
597       /* EVIDENCE-OF: R-58063-38258 SQLITE_CONFIG_MMAP_SIZE takes two 64-bit
598       ** integer (sqlite3_int64) values that are the default mmap size limit
599       ** (the default setting for PRAGMA mmap_size) and the maximum allowed
600       ** mmap size limit. */
601       sqlite3_int64 szMmap = va_arg(ap, sqlite3_int64);
602       sqlite3_int64 mxMmap = va_arg(ap, sqlite3_int64);
603       /* EVIDENCE-OF: R-53367-43190 If either argument to this option is
604       ** negative, then that argument is changed to its compile-time default.
605       **
606       ** EVIDENCE-OF: R-34993-45031 The maximum allowed mmap size will be
607       ** silently truncated if necessary so that it does not exceed the
608       ** compile-time maximum mmap size set by the SQLITE_MAX_MMAP_SIZE
609       ** compile-time option.
610       */
611       if( mxMmap<0 || mxMmap>SQLITE_MAX_MMAP_SIZE ){
612         mxMmap = SQLITE_MAX_MMAP_SIZE;
613       }
614       if( szMmap<0 ) szMmap = SQLITE_DEFAULT_MMAP_SIZE;
615       if( szMmap>mxMmap) szMmap = mxMmap;
616       sqlite3GlobalConfig.mxMmap = mxMmap;
617       sqlite3GlobalConfig.szMmap = szMmap;
618       break;
619     }
620 
621 #if SQLITE_OS_WIN && defined(SQLITE_WIN32_MALLOC) /* IMP: R-04780-55815 */
622     case SQLITE_CONFIG_WIN32_HEAPSIZE: {
623       /* EVIDENCE-OF: R-34926-03360 SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit
624       ** unsigned integer value that specifies the maximum size of the created
625       ** heap. */
626       sqlite3GlobalConfig.nHeap = va_arg(ap, int);
627       break;
628     }
629 #endif
630 
631     case SQLITE_CONFIG_PMASZ: {
632       sqlite3GlobalConfig.szPma = va_arg(ap, unsigned int);
633       break;
634     }
635 
636     case SQLITE_CONFIG_STMTJRNL_SPILL: {
637       sqlite3GlobalConfig.nStmtSpill = va_arg(ap, int);
638       break;
639     }
640 
641     default: {
642       rc = SQLITE_ERROR;
643       break;
644     }
645   }
646   va_end(ap);
647   return rc;
648 }
649 
650 /*
651 ** Set up the lookaside buffers for a database connection.
652 ** Return SQLITE_OK on success.
653 ** If lookaside is already active, return SQLITE_BUSY.
654 **
655 ** The sz parameter is the number of bytes in each lookaside slot.
656 ** The cnt parameter is the number of slots.  If pStart is NULL the
657 ** space for the lookaside memory is obtained from sqlite3_malloc().
658 ** If pStart is not NULL then it is sz*cnt bytes of memory to use for
659 ** the lookaside memory.
660 */
661 static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
662 #ifndef SQLITE_OMIT_LOOKASIDE
663   void *pStart;
664   if( db->lookaside.nOut ){
665     return SQLITE_BUSY;
666   }
667   /* Free any existing lookaside buffer for this handle before
668   ** allocating a new one so we don't have to have space for
669   ** both at the same time.
670   */
671   if( db->lookaside.bMalloced ){
672     sqlite3_free(db->lookaside.pStart);
673   }
674   /* The size of a lookaside slot after ROUNDDOWN8 needs to be larger
675   ** than a pointer to be useful.
676   */
677   sz = ROUNDDOWN8(sz);  /* IMP: R-33038-09382 */
678   if( sz<=(int)sizeof(LookasideSlot*) ) sz = 0;
679   if( cnt<0 ) cnt = 0;
680   if( sz==0 || cnt==0 ){
681     sz = 0;
682     pStart = 0;
683   }else if( pBuf==0 ){
684     sqlite3BeginBenignMalloc();
685     pStart = sqlite3Malloc( sz*cnt );  /* IMP: R-61949-35727 */
686     sqlite3EndBenignMalloc();
687     if( pStart ) cnt = sqlite3MallocSize(pStart)/sz;
688   }else{
689     pStart = pBuf;
690   }
691   db->lookaside.pStart = pStart;
692   db->lookaside.pFree = 0;
693   db->lookaside.sz = (u16)sz;
694   if( pStart ){
695     int i;
696     LookasideSlot *p;
697     assert( sz > (int)sizeof(LookasideSlot*) );
698     p = (LookasideSlot*)pStart;
699     for(i=cnt-1; i>=0; i--){
700       p->pNext = db->lookaside.pFree;
701       db->lookaside.pFree = p;
702       p = (LookasideSlot*)&((u8*)p)[sz];
703     }
704     db->lookaside.pEnd = p;
705     db->lookaside.bDisable = 0;
706     db->lookaside.bMalloced = pBuf==0 ?1:0;
707   }else{
708     db->lookaside.pStart = db;
709     db->lookaside.pEnd = db;
710     db->lookaside.bDisable = 1;
711     db->lookaside.bMalloced = 0;
712   }
713 #endif /* SQLITE_OMIT_LOOKASIDE */
714   return SQLITE_OK;
715 }
716 
717 /*
718 ** Return the mutex associated with a database connection.
719 */
720 sqlite3_mutex *sqlite3_db_mutex(sqlite3 *db){
721 #ifdef SQLITE_ENABLE_API_ARMOR
722   if( !sqlite3SafetyCheckOk(db) ){
723     (void)SQLITE_MISUSE_BKPT;
724     return 0;
725   }
726 #endif
727   return db->mutex;
728 }
729 
730 /*
731 ** Free up as much memory as we can from the given database
732 ** connection.
733 */
734 int sqlite3_db_release_memory(sqlite3 *db){
735   int i;
736 
737 #ifdef SQLITE_ENABLE_API_ARMOR
738   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
739 #endif
740   sqlite3_mutex_enter(db->mutex);
741   sqlite3BtreeEnterAll(db);
742   for(i=0; i<db->nDb; i++){
743     Btree *pBt = db->aDb[i].pBt;
744     if( pBt ){
745       Pager *pPager = sqlite3BtreePager(pBt);
746       sqlite3PagerShrink(pPager);
747     }
748   }
749   sqlite3BtreeLeaveAll(db);
750   sqlite3_mutex_leave(db->mutex);
751   return SQLITE_OK;
752 }
753 
754 /*
755 ** Flush any dirty pages in the pager-cache for any attached database
756 ** to disk.
757 */
758 int sqlite3_db_cacheflush(sqlite3 *db){
759   int i;
760   int rc = SQLITE_OK;
761   int bSeenBusy = 0;
762 
763 #ifdef SQLITE_ENABLE_API_ARMOR
764   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
765 #endif
766   sqlite3_mutex_enter(db->mutex);
767   sqlite3BtreeEnterAll(db);
768   for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
769     Btree *pBt = db->aDb[i].pBt;
770     if( pBt && sqlite3BtreeIsInTrans(pBt) ){
771       Pager *pPager = sqlite3BtreePager(pBt);
772       rc = sqlite3PagerFlush(pPager);
773       if( rc==SQLITE_BUSY ){
774         bSeenBusy = 1;
775         rc = SQLITE_OK;
776       }
777     }
778   }
779   sqlite3BtreeLeaveAll(db);
780   sqlite3_mutex_leave(db->mutex);
781   return ((rc==SQLITE_OK && bSeenBusy) ? SQLITE_BUSY : rc);
782 }
783 
784 /*
785 ** Configuration settings for an individual database connection
786 */
787 int sqlite3_db_config(sqlite3 *db, int op, ...){
788   va_list ap;
789   int rc;
790   va_start(ap, op);
791   switch( op ){
792     case SQLITE_DBCONFIG_MAINDBNAME: {
793       db->aDb[0].zDbSName = va_arg(ap,char*);
794       rc = SQLITE_OK;
795       break;
796     }
797     case SQLITE_DBCONFIG_LOOKASIDE: {
798       void *pBuf = va_arg(ap, void*); /* IMP: R-26835-10964 */
799       int sz = va_arg(ap, int);       /* IMP: R-47871-25994 */
800       int cnt = va_arg(ap, int);      /* IMP: R-04460-53386 */
801       rc = setupLookaside(db, pBuf, sz, cnt);
802       break;
803     }
804     default: {
805       static const struct {
806         int op;      /* The opcode */
807         u32 mask;    /* Mask of the bit in sqlite3.flags to set/clear */
808       } aFlagOp[] = {
809         { SQLITE_DBCONFIG_ENABLE_FKEY,           SQLITE_ForeignKeys    },
810         { SQLITE_DBCONFIG_ENABLE_TRIGGER,        SQLITE_EnableTrigger  },
811         { SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER, SQLITE_Fts3Tokenizer  },
812         { SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, SQLITE_LoadExtension  },
813         { SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE,      SQLITE_NoCkptOnClose  },
814       };
815       unsigned int i;
816       rc = SQLITE_ERROR; /* IMP: R-42790-23372 */
817       for(i=0; i<ArraySize(aFlagOp); i++){
818         if( aFlagOp[i].op==op ){
819           int onoff = va_arg(ap, int);
820           int *pRes = va_arg(ap, int*);
821           int oldFlags = db->flags;
822           if( onoff>0 ){
823             db->flags |= aFlagOp[i].mask;
824           }else if( onoff==0 ){
825             db->flags &= ~aFlagOp[i].mask;
826           }
827           if( oldFlags!=db->flags ){
828             sqlite3ExpirePreparedStatements(db);
829           }
830           if( pRes ){
831             *pRes = (db->flags & aFlagOp[i].mask)!=0;
832           }
833           rc = SQLITE_OK;
834           break;
835         }
836       }
837       break;
838     }
839   }
840   va_end(ap);
841   return rc;
842 }
843 
844 
845 /*
846 ** Return true if the buffer z[0..n-1] contains all spaces.
847 */
848 static int allSpaces(const char *z, int n){
849   while( n>0 && z[n-1]==' ' ){ n--; }
850   return n==0;
851 }
852 
853 /*
854 ** This is the default collating function named "BINARY" which is always
855 ** available.
856 **
857 ** If the padFlag argument is not NULL then space padding at the end
858 ** of strings is ignored.  This implements the RTRIM collation.
859 */
860 static int binCollFunc(
861   void *padFlag,
862   int nKey1, const void *pKey1,
863   int nKey2, const void *pKey2
864 ){
865   int rc, n;
866   n = nKey1<nKey2 ? nKey1 : nKey2;
867   /* EVIDENCE-OF: R-65033-28449 The built-in BINARY collation compares
868   ** strings byte by byte using the memcmp() function from the standard C
869   ** library. */
870   rc = memcmp(pKey1, pKey2, n);
871   if( rc==0 ){
872     if( padFlag
873      && allSpaces(((char*)pKey1)+n, nKey1-n)
874      && allSpaces(((char*)pKey2)+n, nKey2-n)
875     ){
876       /* EVIDENCE-OF: R-31624-24737 RTRIM is like BINARY except that extra
877       ** spaces at the end of either string do not change the result. In other
878       ** words, strings will compare equal to one another as long as they
879       ** differ only in the number of spaces at the end.
880       */
881     }else{
882       rc = nKey1 - nKey2;
883     }
884   }
885   return rc;
886 }
887 
888 /*
889 ** Another built-in collating sequence: NOCASE.
890 **
891 ** This collating sequence is intended to be used for "case independent
892 ** comparison". SQLite's knowledge of upper and lower case equivalents
893 ** extends only to the 26 characters used in the English language.
894 **
895 ** At the moment there is only a UTF-8 implementation.
896 */
897 static int nocaseCollatingFunc(
898   void *NotUsed,
899   int nKey1, const void *pKey1,
900   int nKey2, const void *pKey2
901 ){
902   int r = sqlite3StrNICmp(
903       (const char *)pKey1, (const char *)pKey2, (nKey1<nKey2)?nKey1:nKey2);
904   UNUSED_PARAMETER(NotUsed);
905   if( 0==r ){
906     r = nKey1-nKey2;
907   }
908   return r;
909 }
910 
911 /*
912 ** Return the ROWID of the most recent insert
913 */
914 sqlite_int64 sqlite3_last_insert_rowid(sqlite3 *db){
915 #ifdef SQLITE_ENABLE_API_ARMOR
916   if( !sqlite3SafetyCheckOk(db) ){
917     (void)SQLITE_MISUSE_BKPT;
918     return 0;
919   }
920 #endif
921   return db->lastRowid;
922 }
923 
924 /*
925 ** Set the value returned by the sqlite3_last_insert_rowid() API function.
926 */
927 void sqlite3_set_last_insert_rowid(sqlite3 *db, sqlite3_int64 iRowid){
928 #ifdef SQLITE_ENABLE_API_ARMOR
929   if( !sqlite3SafetyCheckOk(db) ){
930     (void)SQLITE_MISUSE_BKPT;
931     return;
932   }
933 #endif
934   sqlite3_mutex_enter(db->mutex);
935   db->lastRowid = iRowid;
936   sqlite3_mutex_leave(db->mutex);
937 }
938 
939 /*
940 ** Return the number of changes in the most recent call to sqlite3_exec().
941 */
942 int sqlite3_changes(sqlite3 *db){
943 #ifdef SQLITE_ENABLE_API_ARMOR
944   if( !sqlite3SafetyCheckOk(db) ){
945     (void)SQLITE_MISUSE_BKPT;
946     return 0;
947   }
948 #endif
949   return db->nChange;
950 }
951 
952 /*
953 ** Return the number of changes since the database handle was opened.
954 */
955 int sqlite3_total_changes(sqlite3 *db){
956 #ifdef SQLITE_ENABLE_API_ARMOR
957   if( !sqlite3SafetyCheckOk(db) ){
958     (void)SQLITE_MISUSE_BKPT;
959     return 0;
960   }
961 #endif
962   return db->nTotalChange;
963 }
964 
965 /*
966 ** Close all open savepoints. This function only manipulates fields of the
967 ** database handle object, it does not close any savepoints that may be open
968 ** at the b-tree/pager level.
969 */
970 void sqlite3CloseSavepoints(sqlite3 *db){
971   while( db->pSavepoint ){
972     Savepoint *pTmp = db->pSavepoint;
973     db->pSavepoint = pTmp->pNext;
974     sqlite3DbFree(db, pTmp);
975   }
976   db->nSavepoint = 0;
977   db->nStatement = 0;
978   db->isTransactionSavepoint = 0;
979 }
980 
981 /*
982 ** Invoke the destructor function associated with FuncDef p, if any. Except,
983 ** if this is not the last copy of the function, do not invoke it. Multiple
984 ** copies of a single function are created when create_function() is called
985 ** with SQLITE_ANY as the encoding.
986 */
987 static void functionDestroy(sqlite3 *db, FuncDef *p){
988   FuncDestructor *pDestructor = p->u.pDestructor;
989   if( pDestructor ){
990     pDestructor->nRef--;
991     if( pDestructor->nRef==0 ){
992       pDestructor->xDestroy(pDestructor->pUserData);
993       sqlite3DbFree(db, pDestructor);
994     }
995   }
996 }
997 
998 /*
999 ** Disconnect all sqlite3_vtab objects that belong to database connection
1000 ** db. This is called when db is being closed.
1001 */
1002 static void disconnectAllVtab(sqlite3 *db){
1003 #ifndef SQLITE_OMIT_VIRTUALTABLE
1004   int i;
1005   HashElem *p;
1006   sqlite3BtreeEnterAll(db);
1007   for(i=0; i<db->nDb; i++){
1008     Schema *pSchema = db->aDb[i].pSchema;
1009     if( db->aDb[i].pSchema ){
1010       for(p=sqliteHashFirst(&pSchema->tblHash); p; p=sqliteHashNext(p)){
1011         Table *pTab = (Table *)sqliteHashData(p);
1012         if( IsVirtual(pTab) ) sqlite3VtabDisconnect(db, pTab);
1013       }
1014     }
1015   }
1016   for(p=sqliteHashFirst(&db->aModule); p; p=sqliteHashNext(p)){
1017     Module *pMod = (Module *)sqliteHashData(p);
1018     if( pMod->pEpoTab ){
1019       sqlite3VtabDisconnect(db, pMod->pEpoTab);
1020     }
1021   }
1022   sqlite3VtabUnlockList(db);
1023   sqlite3BtreeLeaveAll(db);
1024 #else
1025   UNUSED_PARAMETER(db);
1026 #endif
1027 }
1028 
1029 /*
1030 ** Return TRUE if database connection db has unfinalized prepared
1031 ** statements or unfinished sqlite3_backup objects.
1032 */
1033 static int connectionIsBusy(sqlite3 *db){
1034   int j;
1035   assert( sqlite3_mutex_held(db->mutex) );
1036   if( db->pVdbe ) return 1;
1037   for(j=0; j<db->nDb; j++){
1038     Btree *pBt = db->aDb[j].pBt;
1039     if( pBt && sqlite3BtreeIsInBackup(pBt) ) return 1;
1040   }
1041   return 0;
1042 }
1043 
1044 /*
1045 ** Close an existing SQLite database
1046 */
1047 static int sqlite3Close(sqlite3 *db, int forceZombie){
1048   if( !db ){
1049     /* EVIDENCE-OF: R-63257-11740 Calling sqlite3_close() or
1050     ** sqlite3_close_v2() with a NULL pointer argument is a harmless no-op. */
1051     return SQLITE_OK;
1052   }
1053   if( !sqlite3SafetyCheckSickOrOk(db) ){
1054     return SQLITE_MISUSE_BKPT;
1055   }
1056   sqlite3_mutex_enter(db->mutex);
1057   if( db->mTrace & SQLITE_TRACE_CLOSE ){
1058     db->xTrace(SQLITE_TRACE_CLOSE, db->pTraceArg, db, 0);
1059   }
1060 
1061   /* Force xDisconnect calls on all virtual tables */
1062   disconnectAllVtab(db);
1063 
1064   /* If a transaction is open, the disconnectAllVtab() call above
1065   ** will not have called the xDisconnect() method on any virtual
1066   ** tables in the db->aVTrans[] array. The following sqlite3VtabRollback()
1067   ** call will do so. We need to do this before the check for active
1068   ** SQL statements below, as the v-table implementation may be storing
1069   ** some prepared statements internally.
1070   */
1071   sqlite3VtabRollback(db);
1072 
1073   /* Legacy behavior (sqlite3_close() behavior) is to return
1074   ** SQLITE_BUSY if the connection can not be closed immediately.
1075   */
1076   if( !forceZombie && connectionIsBusy(db) ){
1077     sqlite3ErrorWithMsg(db, SQLITE_BUSY, "unable to close due to unfinalized "
1078        "statements or unfinished backups");
1079     sqlite3_mutex_leave(db->mutex);
1080     return SQLITE_BUSY;
1081   }
1082 
1083 #ifdef SQLITE_ENABLE_SQLLOG
1084   if( sqlite3GlobalConfig.xSqllog ){
1085     /* Closing the handle. Fourth parameter is passed the value 2. */
1086     sqlite3GlobalConfig.xSqllog(sqlite3GlobalConfig.pSqllogArg, db, 0, 2);
1087   }
1088 #endif
1089 
1090   /* Convert the connection into a zombie and then close it.
1091   */
1092   db->magic = SQLITE_MAGIC_ZOMBIE;
1093   sqlite3LeaveMutexAndCloseZombie(db);
1094   return SQLITE_OK;
1095 }
1096 
1097 /*
1098 ** Two variations on the public interface for closing a database
1099 ** connection. The sqlite3_close() version returns SQLITE_BUSY and
1100 ** leaves the connection option if there are unfinalized prepared
1101 ** statements or unfinished sqlite3_backups.  The sqlite3_close_v2()
1102 ** version forces the connection to become a zombie if there are
1103 ** unclosed resources, and arranges for deallocation when the last
1104 ** prepare statement or sqlite3_backup closes.
1105 */
1106 int sqlite3_close(sqlite3 *db){ return sqlite3Close(db,0); }
1107 int sqlite3_close_v2(sqlite3 *db){ return sqlite3Close(db,1); }
1108 
1109 
1110 /*
1111 ** Close the mutex on database connection db.
1112 **
1113 ** Furthermore, if database connection db is a zombie (meaning that there
1114 ** has been a prior call to sqlite3_close(db) or sqlite3_close_v2(db)) and
1115 ** every sqlite3_stmt has now been finalized and every sqlite3_backup has
1116 ** finished, then free all resources.
1117 */
1118 void sqlite3LeaveMutexAndCloseZombie(sqlite3 *db){
1119   HashElem *i;                    /* Hash table iterator */
1120   int j;
1121 
1122   /* If there are outstanding sqlite3_stmt or sqlite3_backup objects
1123   ** or if the connection has not yet been closed by sqlite3_close_v2(),
1124   ** then just leave the mutex and return.
1125   */
1126   if( db->magic!=SQLITE_MAGIC_ZOMBIE || connectionIsBusy(db) ){
1127     sqlite3_mutex_leave(db->mutex);
1128     return;
1129   }
1130 
1131   /* If we reach this point, it means that the database connection has
1132   ** closed all sqlite3_stmt and sqlite3_backup objects and has been
1133   ** passed to sqlite3_close (meaning that it is a zombie).  Therefore,
1134   ** go ahead and free all resources.
1135   */
1136 
1137   /* If a transaction is open, roll it back. This also ensures that if
1138   ** any database schemas have been modified by an uncommitted transaction
1139   ** they are reset. And that the required b-tree mutex is held to make
1140   ** the pager rollback and schema reset an atomic operation. */
1141   sqlite3RollbackAll(db, SQLITE_OK);
1142 
1143   /* Free any outstanding Savepoint structures. */
1144   sqlite3CloseSavepoints(db);
1145 
1146   /* Close all database connections */
1147   for(j=0; j<db->nDb; j++){
1148     struct Db *pDb = &db->aDb[j];
1149     if( pDb->pBt ){
1150       sqlite3BtreeClose(pDb->pBt);
1151       pDb->pBt = 0;
1152       if( j!=1 ){
1153         pDb->pSchema = 0;
1154       }
1155     }
1156   }
1157   /* Clear the TEMP schema separately and last */
1158   if( db->aDb[1].pSchema ){
1159     sqlite3SchemaClear(db->aDb[1].pSchema);
1160   }
1161   sqlite3VtabUnlockList(db);
1162 
1163   /* Free up the array of auxiliary databases */
1164   sqlite3CollapseDatabaseArray(db);
1165   assert( db->nDb<=2 );
1166   assert( db->aDb==db->aDbStatic );
1167 
1168   /* Tell the code in notify.c that the connection no longer holds any
1169   ** locks and does not require any further unlock-notify callbacks.
1170   */
1171   sqlite3ConnectionClosed(db);
1172 
1173   for(i=sqliteHashFirst(&db->aFunc); i; i=sqliteHashNext(i)){
1174     FuncDef *pNext, *p;
1175     p = sqliteHashData(i);
1176     do{
1177       functionDestroy(db, p);
1178       pNext = p->pNext;
1179       sqlite3DbFree(db, p);
1180       p = pNext;
1181     }while( p );
1182   }
1183   sqlite3HashClear(&db->aFunc);
1184   for(i=sqliteHashFirst(&db->aCollSeq); i; i=sqliteHashNext(i)){
1185     CollSeq *pColl = (CollSeq *)sqliteHashData(i);
1186     /* Invoke any destructors registered for collation sequence user data. */
1187     for(j=0; j<3; j++){
1188       if( pColl[j].xDel ){
1189         pColl[j].xDel(pColl[j].pUser);
1190       }
1191     }
1192     sqlite3DbFree(db, pColl);
1193   }
1194   sqlite3HashClear(&db->aCollSeq);
1195 #ifndef SQLITE_OMIT_VIRTUALTABLE
1196   for(i=sqliteHashFirst(&db->aModule); i; i=sqliteHashNext(i)){
1197     Module *pMod = (Module *)sqliteHashData(i);
1198     if( pMod->xDestroy ){
1199       pMod->xDestroy(pMod->pAux);
1200     }
1201     sqlite3VtabEponymousTableClear(db, pMod);
1202     sqlite3DbFree(db, pMod);
1203   }
1204   sqlite3HashClear(&db->aModule);
1205 #endif
1206 
1207   sqlite3Error(db, SQLITE_OK); /* Deallocates any cached error strings. */
1208   sqlite3ValueFree(db->pErr);
1209   sqlite3CloseExtensions(db);
1210 #if SQLITE_USER_AUTHENTICATION
1211   sqlite3_free(db->auth.zAuthUser);
1212   sqlite3_free(db->auth.zAuthPW);
1213 #endif
1214 
1215   db->magic = SQLITE_MAGIC_ERROR;
1216 
1217   /* The temp-database schema is allocated differently from the other schema
1218   ** objects (using sqliteMalloc() directly, instead of sqlite3BtreeSchema()).
1219   ** So it needs to be freed here. Todo: Why not roll the temp schema into
1220   ** the same sqliteMalloc() as the one that allocates the database
1221   ** structure?
1222   */
1223   sqlite3DbFree(db, db->aDb[1].pSchema);
1224   sqlite3_mutex_leave(db->mutex);
1225   db->magic = SQLITE_MAGIC_CLOSED;
1226   sqlite3_mutex_free(db->mutex);
1227   assert( db->lookaside.nOut==0 );  /* Fails on a lookaside memory leak */
1228   if( db->lookaside.bMalloced ){
1229     sqlite3_free(db->lookaside.pStart);
1230   }
1231   sqlite3_free(db);
1232 }
1233 
1234 /*
1235 ** Rollback all database files.  If tripCode is not SQLITE_OK, then
1236 ** any write cursors are invalidated ("tripped" - as in "tripping a circuit
1237 ** breaker") and made to return tripCode if there are any further
1238 ** attempts to use that cursor.  Read cursors remain open and valid
1239 ** but are "saved" in case the table pages are moved around.
1240 */
1241 void sqlite3RollbackAll(sqlite3 *db, int tripCode){
1242   int i;
1243   int inTrans = 0;
1244   int schemaChange;
1245   assert( sqlite3_mutex_held(db->mutex) );
1246   sqlite3BeginBenignMalloc();
1247 
1248   /* Obtain all b-tree mutexes before making any calls to BtreeRollback().
1249   ** This is important in case the transaction being rolled back has
1250   ** modified the database schema. If the b-tree mutexes are not taken
1251   ** here, then another shared-cache connection might sneak in between
1252   ** the database rollback and schema reset, which can cause false
1253   ** corruption reports in some cases.  */
1254   sqlite3BtreeEnterAll(db);
1255   schemaChange = (db->flags & SQLITE_InternChanges)!=0 && db->init.busy==0;
1256 
1257   for(i=0; i<db->nDb; i++){
1258     Btree *p = db->aDb[i].pBt;
1259     if( p ){
1260       if( sqlite3BtreeIsInTrans(p) ){
1261         inTrans = 1;
1262       }
1263       sqlite3BtreeRollback(p, tripCode, !schemaChange);
1264     }
1265   }
1266   sqlite3VtabRollback(db);
1267   sqlite3EndBenignMalloc();
1268 
1269   if( (db->flags&SQLITE_InternChanges)!=0 && db->init.busy==0 ){
1270     sqlite3ExpirePreparedStatements(db);
1271     sqlite3ResetAllSchemasOfConnection(db);
1272   }
1273   sqlite3BtreeLeaveAll(db);
1274 
1275   /* Any deferred constraint violations have now been resolved. */
1276   db->nDeferredCons = 0;
1277   db->nDeferredImmCons = 0;
1278   db->flags &= ~SQLITE_DeferFKs;
1279 
1280   /* If one has been configured, invoke the rollback-hook callback */
1281   if( db->xRollbackCallback && (inTrans || !db->autoCommit) ){
1282     db->xRollbackCallback(db->pRollbackArg);
1283   }
1284 }
1285 
1286 /*
1287 ** Return a static string containing the name corresponding to the error code
1288 ** specified in the argument.
1289 */
1290 #if defined(SQLITE_NEED_ERR_NAME)
1291 const char *sqlite3ErrName(int rc){
1292   const char *zName = 0;
1293   int i, origRc = rc;
1294   for(i=0; i<2 && zName==0; i++, rc &= 0xff){
1295     switch( rc ){
1296       case SQLITE_OK:                 zName = "SQLITE_OK";                break;
1297       case SQLITE_ERROR:              zName = "SQLITE_ERROR";             break;
1298       case SQLITE_INTERNAL:           zName = "SQLITE_INTERNAL";          break;
1299       case SQLITE_PERM:               zName = "SQLITE_PERM";              break;
1300       case SQLITE_ABORT:              zName = "SQLITE_ABORT";             break;
1301       case SQLITE_ABORT_ROLLBACK:     zName = "SQLITE_ABORT_ROLLBACK";    break;
1302       case SQLITE_BUSY:               zName = "SQLITE_BUSY";              break;
1303       case SQLITE_BUSY_RECOVERY:      zName = "SQLITE_BUSY_RECOVERY";     break;
1304       case SQLITE_BUSY_SNAPSHOT:      zName = "SQLITE_BUSY_SNAPSHOT";     break;
1305       case SQLITE_LOCKED:             zName = "SQLITE_LOCKED";            break;
1306       case SQLITE_LOCKED_SHAREDCACHE: zName = "SQLITE_LOCKED_SHAREDCACHE";break;
1307       case SQLITE_NOMEM:              zName = "SQLITE_NOMEM";             break;
1308       case SQLITE_READONLY:           zName = "SQLITE_READONLY";          break;
1309       case SQLITE_READONLY_RECOVERY:  zName = "SQLITE_READONLY_RECOVERY"; break;
1310       case SQLITE_READONLY_CANTLOCK:  zName = "SQLITE_READONLY_CANTLOCK"; break;
1311       case SQLITE_READONLY_ROLLBACK:  zName = "SQLITE_READONLY_ROLLBACK"; break;
1312       case SQLITE_READONLY_DBMOVED:   zName = "SQLITE_READONLY_DBMOVED";  break;
1313       case SQLITE_INTERRUPT:          zName = "SQLITE_INTERRUPT";         break;
1314       case SQLITE_IOERR:              zName = "SQLITE_IOERR";             break;
1315       case SQLITE_IOERR_READ:         zName = "SQLITE_IOERR_READ";        break;
1316       case SQLITE_IOERR_SHORT_READ:   zName = "SQLITE_IOERR_SHORT_READ";  break;
1317       case SQLITE_IOERR_WRITE:        zName = "SQLITE_IOERR_WRITE";       break;
1318       case SQLITE_IOERR_FSYNC:        zName = "SQLITE_IOERR_FSYNC";       break;
1319       case SQLITE_IOERR_DIR_FSYNC:    zName = "SQLITE_IOERR_DIR_FSYNC";   break;
1320       case SQLITE_IOERR_TRUNCATE:     zName = "SQLITE_IOERR_TRUNCATE";    break;
1321       case SQLITE_IOERR_FSTAT:        zName = "SQLITE_IOERR_FSTAT";       break;
1322       case SQLITE_IOERR_UNLOCK:       zName = "SQLITE_IOERR_UNLOCK";      break;
1323       case SQLITE_IOERR_RDLOCK:       zName = "SQLITE_IOERR_RDLOCK";      break;
1324       case SQLITE_IOERR_DELETE:       zName = "SQLITE_IOERR_DELETE";      break;
1325       case SQLITE_IOERR_NOMEM:        zName = "SQLITE_IOERR_NOMEM";       break;
1326       case SQLITE_IOERR_ACCESS:       zName = "SQLITE_IOERR_ACCESS";      break;
1327       case SQLITE_IOERR_CHECKRESERVEDLOCK:
1328                                 zName = "SQLITE_IOERR_CHECKRESERVEDLOCK"; break;
1329       case SQLITE_IOERR_LOCK:         zName = "SQLITE_IOERR_LOCK";        break;
1330       case SQLITE_IOERR_CLOSE:        zName = "SQLITE_IOERR_CLOSE";       break;
1331       case SQLITE_IOERR_DIR_CLOSE:    zName = "SQLITE_IOERR_DIR_CLOSE";   break;
1332       case SQLITE_IOERR_SHMOPEN:      zName = "SQLITE_IOERR_SHMOPEN";     break;
1333       case SQLITE_IOERR_SHMSIZE:      zName = "SQLITE_IOERR_SHMSIZE";     break;
1334       case SQLITE_IOERR_SHMLOCK:      zName = "SQLITE_IOERR_SHMLOCK";     break;
1335       case SQLITE_IOERR_SHMMAP:       zName = "SQLITE_IOERR_SHMMAP";      break;
1336       case SQLITE_IOERR_SEEK:         zName = "SQLITE_IOERR_SEEK";        break;
1337       case SQLITE_IOERR_DELETE_NOENT: zName = "SQLITE_IOERR_DELETE_NOENT";break;
1338       case SQLITE_IOERR_MMAP:         zName = "SQLITE_IOERR_MMAP";        break;
1339       case SQLITE_IOERR_GETTEMPPATH:  zName = "SQLITE_IOERR_GETTEMPPATH"; break;
1340       case SQLITE_IOERR_CONVPATH:     zName = "SQLITE_IOERR_CONVPATH";    break;
1341       case SQLITE_CORRUPT:            zName = "SQLITE_CORRUPT";           break;
1342       case SQLITE_CORRUPT_VTAB:       zName = "SQLITE_CORRUPT_VTAB";      break;
1343       case SQLITE_NOTFOUND:           zName = "SQLITE_NOTFOUND";          break;
1344       case SQLITE_FULL:               zName = "SQLITE_FULL";              break;
1345       case SQLITE_CANTOPEN:           zName = "SQLITE_CANTOPEN";          break;
1346       case SQLITE_CANTOPEN_NOTEMPDIR: zName = "SQLITE_CANTOPEN_NOTEMPDIR";break;
1347       case SQLITE_CANTOPEN_ISDIR:     zName = "SQLITE_CANTOPEN_ISDIR";    break;
1348       case SQLITE_CANTOPEN_FULLPATH:  zName = "SQLITE_CANTOPEN_FULLPATH"; break;
1349       case SQLITE_CANTOPEN_CONVPATH:  zName = "SQLITE_CANTOPEN_CONVPATH"; break;
1350       case SQLITE_PROTOCOL:           zName = "SQLITE_PROTOCOL";          break;
1351       case SQLITE_EMPTY:              zName = "SQLITE_EMPTY";             break;
1352       case SQLITE_SCHEMA:             zName = "SQLITE_SCHEMA";            break;
1353       case SQLITE_TOOBIG:             zName = "SQLITE_TOOBIG";            break;
1354       case SQLITE_CONSTRAINT:         zName = "SQLITE_CONSTRAINT";        break;
1355       case SQLITE_CONSTRAINT_UNIQUE:  zName = "SQLITE_CONSTRAINT_UNIQUE"; break;
1356       case SQLITE_CONSTRAINT_TRIGGER: zName = "SQLITE_CONSTRAINT_TRIGGER";break;
1357       case SQLITE_CONSTRAINT_FOREIGNKEY:
1358                                 zName = "SQLITE_CONSTRAINT_FOREIGNKEY";   break;
1359       case SQLITE_CONSTRAINT_CHECK:   zName = "SQLITE_CONSTRAINT_CHECK";  break;
1360       case SQLITE_CONSTRAINT_PRIMARYKEY:
1361                                 zName = "SQLITE_CONSTRAINT_PRIMARYKEY";   break;
1362       case SQLITE_CONSTRAINT_NOTNULL: zName = "SQLITE_CONSTRAINT_NOTNULL";break;
1363       case SQLITE_CONSTRAINT_COMMITHOOK:
1364                                 zName = "SQLITE_CONSTRAINT_COMMITHOOK";   break;
1365       case SQLITE_CONSTRAINT_VTAB:    zName = "SQLITE_CONSTRAINT_VTAB";   break;
1366       case SQLITE_CONSTRAINT_FUNCTION:
1367                                 zName = "SQLITE_CONSTRAINT_FUNCTION";     break;
1368       case SQLITE_CONSTRAINT_ROWID:   zName = "SQLITE_CONSTRAINT_ROWID";  break;
1369       case SQLITE_MISMATCH:           zName = "SQLITE_MISMATCH";          break;
1370       case SQLITE_MISUSE:             zName = "SQLITE_MISUSE";            break;
1371       case SQLITE_NOLFS:              zName = "SQLITE_NOLFS";             break;
1372       case SQLITE_AUTH:               zName = "SQLITE_AUTH";              break;
1373       case SQLITE_FORMAT:             zName = "SQLITE_FORMAT";            break;
1374       case SQLITE_RANGE:              zName = "SQLITE_RANGE";             break;
1375       case SQLITE_NOTADB:             zName = "SQLITE_NOTADB";            break;
1376       case SQLITE_ROW:                zName = "SQLITE_ROW";               break;
1377       case SQLITE_NOTICE:             zName = "SQLITE_NOTICE";            break;
1378       case SQLITE_NOTICE_RECOVER_WAL: zName = "SQLITE_NOTICE_RECOVER_WAL";break;
1379       case SQLITE_NOTICE_RECOVER_ROLLBACK:
1380                                 zName = "SQLITE_NOTICE_RECOVER_ROLLBACK"; break;
1381       case SQLITE_WARNING:            zName = "SQLITE_WARNING";           break;
1382       case SQLITE_WARNING_AUTOINDEX:  zName = "SQLITE_WARNING_AUTOINDEX"; break;
1383       case SQLITE_DONE:               zName = "SQLITE_DONE";              break;
1384     }
1385   }
1386   if( zName==0 ){
1387     static char zBuf[50];
1388     sqlite3_snprintf(sizeof(zBuf), zBuf, "SQLITE_UNKNOWN(%d)", origRc);
1389     zName = zBuf;
1390   }
1391   return zName;
1392 }
1393 #endif
1394 
1395 /*
1396 ** Return a static string that describes the kind of error specified in the
1397 ** argument.
1398 */
1399 const char *sqlite3ErrStr(int rc){
1400   static const char* const aMsg[] = {
1401     /* SQLITE_OK          */ "not an error",
1402     /* SQLITE_ERROR       */ "SQL logic error or missing database",
1403     /* SQLITE_INTERNAL    */ 0,
1404     /* SQLITE_PERM        */ "access permission denied",
1405     /* SQLITE_ABORT       */ "callback requested query abort",
1406     /* SQLITE_BUSY        */ "database is locked",
1407     /* SQLITE_LOCKED      */ "database table is locked",
1408     /* SQLITE_NOMEM       */ "out of memory",
1409     /* SQLITE_READONLY    */ "attempt to write a readonly database",
1410     /* SQLITE_INTERRUPT   */ "interrupted",
1411     /* SQLITE_IOERR       */ "disk I/O error",
1412     /* SQLITE_CORRUPT     */ "database disk image is malformed",
1413     /* SQLITE_NOTFOUND    */ "unknown operation",
1414     /* SQLITE_FULL        */ "database or disk is full",
1415     /* SQLITE_CANTOPEN    */ "unable to open database file",
1416     /* SQLITE_PROTOCOL    */ "locking protocol",
1417     /* SQLITE_EMPTY       */ "table contains no data",
1418     /* SQLITE_SCHEMA      */ "database schema has changed",
1419     /* SQLITE_TOOBIG      */ "string or blob too big",
1420     /* SQLITE_CONSTRAINT  */ "constraint failed",
1421     /* SQLITE_MISMATCH    */ "datatype mismatch",
1422     /* SQLITE_MISUSE      */ "library routine called out of sequence",
1423     /* SQLITE_NOLFS       */ "large file support is disabled",
1424     /* SQLITE_AUTH        */ "authorization denied",
1425     /* SQLITE_FORMAT      */ "auxiliary database format error",
1426     /* SQLITE_RANGE       */ "bind or column index out of range",
1427     /* SQLITE_NOTADB      */ "file is encrypted or is not a database",
1428   };
1429   const char *zErr = "unknown error";
1430   switch( rc ){
1431     case SQLITE_ABORT_ROLLBACK: {
1432       zErr = "abort due to ROLLBACK";
1433       break;
1434     }
1435     default: {
1436       rc &= 0xff;
1437       if( ALWAYS(rc>=0) && rc<ArraySize(aMsg) && aMsg[rc]!=0 ){
1438         zErr = aMsg[rc];
1439       }
1440       break;
1441     }
1442   }
1443   return zErr;
1444 }
1445 
1446 /*
1447 ** This routine implements a busy callback that sleeps and tries
1448 ** again until a timeout value is reached.  The timeout value is
1449 ** an integer number of milliseconds passed in as the first
1450 ** argument.
1451 */
1452 static int sqliteDefaultBusyCallback(
1453  void *ptr,               /* Database connection */
1454  int count                /* Number of times table has been busy */
1455 ){
1456 #if SQLITE_OS_WIN || HAVE_USLEEP
1457   static const u8 delays[] =
1458      { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
1459   static const u8 totals[] =
1460      { 0, 1, 3,  8, 18, 33, 53, 78, 103, 128, 178, 228 };
1461 # define NDELAY ArraySize(delays)
1462   sqlite3 *db = (sqlite3 *)ptr;
1463   int timeout = db->busyTimeout;
1464   int delay, prior;
1465 
1466   assert( count>=0 );
1467   if( count < NDELAY ){
1468     delay = delays[count];
1469     prior = totals[count];
1470   }else{
1471     delay = delays[NDELAY-1];
1472     prior = totals[NDELAY-1] + delay*(count-(NDELAY-1));
1473   }
1474   if( prior + delay > timeout ){
1475     delay = timeout - prior;
1476     if( delay<=0 ) return 0;
1477   }
1478   sqlite3OsSleep(db->pVfs, delay*1000);
1479   return 1;
1480 #else
1481   sqlite3 *db = (sqlite3 *)ptr;
1482   int timeout = ((sqlite3 *)ptr)->busyTimeout;
1483   if( (count+1)*1000 > timeout ){
1484     return 0;
1485   }
1486   sqlite3OsSleep(db->pVfs, 1000000);
1487   return 1;
1488 #endif
1489 }
1490 
1491 /*
1492 ** Invoke the given busy handler.
1493 **
1494 ** This routine is called when an operation failed with a lock.
1495 ** If this routine returns non-zero, the lock is retried.  If it
1496 ** returns 0, the operation aborts with an SQLITE_BUSY error.
1497 */
1498 int sqlite3InvokeBusyHandler(BusyHandler *p){
1499   int rc;
1500   if( NEVER(p==0) || p->xFunc==0 || p->nBusy<0 ) return 0;
1501   rc = p->xFunc(p->pArg, p->nBusy);
1502   if( rc==0 ){
1503     p->nBusy = -1;
1504   }else{
1505     p->nBusy++;
1506   }
1507   return rc;
1508 }
1509 
1510 /*
1511 ** This routine sets the busy callback for an Sqlite database to the
1512 ** given callback function with the given argument.
1513 */
1514 int sqlite3_busy_handler(
1515   sqlite3 *db,
1516   int (*xBusy)(void*,int),
1517   void *pArg
1518 ){
1519 #ifdef SQLITE_ENABLE_API_ARMOR
1520   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
1521 #endif
1522   sqlite3_mutex_enter(db->mutex);
1523   db->busyHandler.xFunc = xBusy;
1524   db->busyHandler.pArg = pArg;
1525   db->busyHandler.nBusy = 0;
1526   db->busyTimeout = 0;
1527   sqlite3_mutex_leave(db->mutex);
1528   return SQLITE_OK;
1529 }
1530 
1531 #ifndef SQLITE_OMIT_PROGRESS_CALLBACK
1532 /*
1533 ** This routine sets the progress callback for an Sqlite database to the
1534 ** given callback function with the given argument. The progress callback will
1535 ** be invoked every nOps opcodes.
1536 */
1537 void sqlite3_progress_handler(
1538   sqlite3 *db,
1539   int nOps,
1540   int (*xProgress)(void*),
1541   void *pArg
1542 ){
1543 #ifdef SQLITE_ENABLE_API_ARMOR
1544   if( !sqlite3SafetyCheckOk(db) ){
1545     (void)SQLITE_MISUSE_BKPT;
1546     return;
1547   }
1548 #endif
1549   sqlite3_mutex_enter(db->mutex);
1550   if( nOps>0 ){
1551     db->xProgress = xProgress;
1552     db->nProgressOps = (unsigned)nOps;
1553     db->pProgressArg = pArg;
1554   }else{
1555     db->xProgress = 0;
1556     db->nProgressOps = 0;
1557     db->pProgressArg = 0;
1558   }
1559   sqlite3_mutex_leave(db->mutex);
1560 }
1561 #endif
1562 
1563 
1564 /*
1565 ** This routine installs a default busy handler that waits for the
1566 ** specified number of milliseconds before returning 0.
1567 */
1568 int sqlite3_busy_timeout(sqlite3 *db, int ms){
1569 #ifdef SQLITE_ENABLE_API_ARMOR
1570   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
1571 #endif
1572   if( ms>0 ){
1573     sqlite3_busy_handler(db, sqliteDefaultBusyCallback, (void*)db);
1574     db->busyTimeout = ms;
1575   }else{
1576     sqlite3_busy_handler(db, 0, 0);
1577   }
1578   return SQLITE_OK;
1579 }
1580 
1581 /*
1582 ** Cause any pending operation to stop at its earliest opportunity.
1583 */
1584 void sqlite3_interrupt(sqlite3 *db){
1585 #ifdef SQLITE_ENABLE_API_ARMOR
1586   if( !sqlite3SafetyCheckOk(db) && (db==0 || db->magic!=SQLITE_MAGIC_ZOMBIE) ){
1587     (void)SQLITE_MISUSE_BKPT;
1588     return;
1589   }
1590 #endif
1591   db->u1.isInterrupted = 1;
1592 }
1593 
1594 
1595 /*
1596 ** This function is exactly the same as sqlite3_create_function(), except
1597 ** that it is designed to be called by internal code. The difference is
1598 ** that if a malloc() fails in sqlite3_create_function(), an error code
1599 ** is returned and the mallocFailed flag cleared.
1600 */
1601 int sqlite3CreateFunc(
1602   sqlite3 *db,
1603   const char *zFunctionName,
1604   int nArg,
1605   int enc,
1606   void *pUserData,
1607   void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
1608   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1609   void (*xFinal)(sqlite3_context*),
1610   FuncDestructor *pDestructor
1611 ){
1612   FuncDef *p;
1613   int nName;
1614   int extraFlags;
1615 
1616   assert( sqlite3_mutex_held(db->mutex) );
1617   if( zFunctionName==0 ||
1618       (xSFunc && (xFinal || xStep)) ||
1619       (!xSFunc && (xFinal && !xStep)) ||
1620       (!xSFunc && (!xFinal && xStep)) ||
1621       (nArg<-1 || nArg>SQLITE_MAX_FUNCTION_ARG) ||
1622       (255<(nName = sqlite3Strlen30( zFunctionName))) ){
1623     return SQLITE_MISUSE_BKPT;
1624   }
1625 
1626   assert( SQLITE_FUNC_CONSTANT==SQLITE_DETERMINISTIC );
1627   extraFlags = enc &  SQLITE_DETERMINISTIC;
1628   enc &= (SQLITE_FUNC_ENCMASK|SQLITE_ANY);
1629 
1630 #ifndef SQLITE_OMIT_UTF16
1631   /* If SQLITE_UTF16 is specified as the encoding type, transform this
1632   ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
1633   ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
1634   **
1635   ** If SQLITE_ANY is specified, add three versions of the function
1636   ** to the hash table.
1637   */
1638   if( enc==SQLITE_UTF16 ){
1639     enc = SQLITE_UTF16NATIVE;
1640   }else if( enc==SQLITE_ANY ){
1641     int rc;
1642     rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF8|extraFlags,
1643          pUserData, xSFunc, xStep, xFinal, pDestructor);
1644     if( rc==SQLITE_OK ){
1645       rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF16LE|extraFlags,
1646           pUserData, xSFunc, xStep, xFinal, pDestructor);
1647     }
1648     if( rc!=SQLITE_OK ){
1649       return rc;
1650     }
1651     enc = SQLITE_UTF16BE;
1652   }
1653 #else
1654   enc = SQLITE_UTF8;
1655 #endif
1656 
1657   /* Check if an existing function is being overridden or deleted. If so,
1658   ** and there are active VMs, then return SQLITE_BUSY. If a function
1659   ** is being overridden/deleted but there are no active VMs, allow the
1660   ** operation to continue but invalidate all precompiled statements.
1661   */
1662   p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 0);
1663   if( p && (p->funcFlags & SQLITE_FUNC_ENCMASK)==enc && p->nArg==nArg ){
1664     if( db->nVdbeActive ){
1665       sqlite3ErrorWithMsg(db, SQLITE_BUSY,
1666         "unable to delete/modify user-function due to active statements");
1667       assert( !db->mallocFailed );
1668       return SQLITE_BUSY;
1669     }else{
1670       sqlite3ExpirePreparedStatements(db);
1671     }
1672   }
1673 
1674   p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 1);
1675   assert(p || db->mallocFailed);
1676   if( !p ){
1677     return SQLITE_NOMEM_BKPT;
1678   }
1679 
1680   /* If an older version of the function with a configured destructor is
1681   ** being replaced invoke the destructor function here. */
1682   functionDestroy(db, p);
1683 
1684   if( pDestructor ){
1685     pDestructor->nRef++;
1686   }
1687   p->u.pDestructor = pDestructor;
1688   p->funcFlags = (p->funcFlags & SQLITE_FUNC_ENCMASK) | extraFlags;
1689   testcase( p->funcFlags & SQLITE_DETERMINISTIC );
1690   p->xSFunc = xSFunc ? xSFunc : xStep;
1691   p->xFinalize = xFinal;
1692   p->pUserData = pUserData;
1693   p->nArg = (u16)nArg;
1694   return SQLITE_OK;
1695 }
1696 
1697 /*
1698 ** Create new user functions.
1699 */
1700 int sqlite3_create_function(
1701   sqlite3 *db,
1702   const char *zFunc,
1703   int nArg,
1704   int enc,
1705   void *p,
1706   void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
1707   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1708   void (*xFinal)(sqlite3_context*)
1709 ){
1710   return sqlite3_create_function_v2(db, zFunc, nArg, enc, p, xSFunc, xStep,
1711                                     xFinal, 0);
1712 }
1713 
1714 int sqlite3_create_function_v2(
1715   sqlite3 *db,
1716   const char *zFunc,
1717   int nArg,
1718   int enc,
1719   void *p,
1720   void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
1721   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
1722   void (*xFinal)(sqlite3_context*),
1723   void (*xDestroy)(void *)
1724 ){
1725   int rc = SQLITE_ERROR;
1726   FuncDestructor *pArg = 0;
1727 
1728 #ifdef SQLITE_ENABLE_API_ARMOR
1729   if( !sqlite3SafetyCheckOk(db) ){
1730     return SQLITE_MISUSE_BKPT;
1731   }
1732 #endif
1733   sqlite3_mutex_enter(db->mutex);
1734   if( xDestroy ){
1735     pArg = (FuncDestructor *)sqlite3DbMallocZero(db, sizeof(FuncDestructor));
1736     if( !pArg ){
1737       xDestroy(p);
1738       goto out;
1739     }
1740     pArg->xDestroy = xDestroy;
1741     pArg->pUserData = p;
1742   }
1743   rc = sqlite3CreateFunc(db, zFunc, nArg, enc, p, xSFunc, xStep, xFinal, pArg);
1744   if( pArg && pArg->nRef==0 ){
1745     assert( rc!=SQLITE_OK );
1746     xDestroy(p);
1747     sqlite3DbFree(db, pArg);
1748   }
1749 
1750  out:
1751   rc = sqlite3ApiExit(db, rc);
1752   sqlite3_mutex_leave(db->mutex);
1753   return rc;
1754 }
1755 
1756 #ifndef SQLITE_OMIT_UTF16
1757 int sqlite3_create_function16(
1758   sqlite3 *db,
1759   const void *zFunctionName,
1760   int nArg,
1761   int eTextRep,
1762   void *p,
1763   void (*xSFunc)(sqlite3_context*,int,sqlite3_value**),
1764   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
1765   void (*xFinal)(sqlite3_context*)
1766 ){
1767   int rc;
1768   char *zFunc8;
1769 
1770 #ifdef SQLITE_ENABLE_API_ARMOR
1771   if( !sqlite3SafetyCheckOk(db) || zFunctionName==0 ) return SQLITE_MISUSE_BKPT;
1772 #endif
1773   sqlite3_mutex_enter(db->mutex);
1774   assert( !db->mallocFailed );
1775   zFunc8 = sqlite3Utf16to8(db, zFunctionName, -1, SQLITE_UTF16NATIVE);
1776   rc = sqlite3CreateFunc(db, zFunc8, nArg, eTextRep, p, xSFunc,xStep,xFinal,0);
1777   sqlite3DbFree(db, zFunc8);
1778   rc = sqlite3ApiExit(db, rc);
1779   sqlite3_mutex_leave(db->mutex);
1780   return rc;
1781 }
1782 #endif
1783 
1784 
1785 /*
1786 ** Declare that a function has been overloaded by a virtual table.
1787 **
1788 ** If the function already exists as a regular global function, then
1789 ** this routine is a no-op.  If the function does not exist, then create
1790 ** a new one that always throws a run-time error.
1791 **
1792 ** When virtual tables intend to provide an overloaded function, they
1793 ** should call this routine to make sure the global function exists.
1794 ** A global function must exist in order for name resolution to work
1795 ** properly.
1796 */
1797 int sqlite3_overload_function(
1798   sqlite3 *db,
1799   const char *zName,
1800   int nArg
1801 ){
1802   int rc = SQLITE_OK;
1803 
1804 #ifdef SQLITE_ENABLE_API_ARMOR
1805   if( !sqlite3SafetyCheckOk(db) || zName==0 || nArg<-2 ){
1806     return SQLITE_MISUSE_BKPT;
1807   }
1808 #endif
1809   sqlite3_mutex_enter(db->mutex);
1810   if( sqlite3FindFunction(db, zName, nArg, SQLITE_UTF8, 0)==0 ){
1811     rc = sqlite3CreateFunc(db, zName, nArg, SQLITE_UTF8,
1812                            0, sqlite3InvalidFunction, 0, 0, 0);
1813   }
1814   rc = sqlite3ApiExit(db, rc);
1815   sqlite3_mutex_leave(db->mutex);
1816   return rc;
1817 }
1818 
1819 #ifndef SQLITE_OMIT_TRACE
1820 /*
1821 ** Register a trace function.  The pArg from the previously registered trace
1822 ** is returned.
1823 **
1824 ** A NULL trace function means that no tracing is executes.  A non-NULL
1825 ** trace is a pointer to a function that is invoked at the start of each
1826 ** SQL statement.
1827 */
1828 #ifndef SQLITE_OMIT_DEPRECATED
1829 void *sqlite3_trace(sqlite3 *db, void(*xTrace)(void*,const char*), void *pArg){
1830   void *pOld;
1831 
1832 #ifdef SQLITE_ENABLE_API_ARMOR
1833   if( !sqlite3SafetyCheckOk(db) ){
1834     (void)SQLITE_MISUSE_BKPT;
1835     return 0;
1836   }
1837 #endif
1838   sqlite3_mutex_enter(db->mutex);
1839   pOld = db->pTraceArg;
1840   db->mTrace = xTrace ? SQLITE_TRACE_LEGACY : 0;
1841   db->xTrace = (int(*)(u32,void*,void*,void*))xTrace;
1842   db->pTraceArg = pArg;
1843   sqlite3_mutex_leave(db->mutex);
1844   return pOld;
1845 }
1846 #endif /* SQLITE_OMIT_DEPRECATED */
1847 
1848 /* Register a trace callback using the version-2 interface.
1849 */
1850 int sqlite3_trace_v2(
1851   sqlite3 *db,                               /* Trace this connection */
1852   unsigned mTrace,                           /* Mask of events to be traced */
1853   int(*xTrace)(unsigned,void*,void*,void*),  /* Callback to invoke */
1854   void *pArg                                 /* Context */
1855 ){
1856 #ifdef SQLITE_ENABLE_API_ARMOR
1857   if( !sqlite3SafetyCheckOk(db) ){
1858     return SQLITE_MISUSE_BKPT;
1859   }
1860 #endif
1861   sqlite3_mutex_enter(db->mutex);
1862   if( mTrace==0 ) xTrace = 0;
1863   if( xTrace==0 ) mTrace = 0;
1864   db->mTrace = mTrace;
1865   db->xTrace = xTrace;
1866   db->pTraceArg = pArg;
1867   sqlite3_mutex_leave(db->mutex);
1868   return SQLITE_OK;
1869 }
1870 
1871 #ifndef SQLITE_OMIT_DEPRECATED
1872 /*
1873 ** Register a profile function.  The pArg from the previously registered
1874 ** profile function is returned.
1875 **
1876 ** A NULL profile function means that no profiling is executes.  A non-NULL
1877 ** profile is a pointer to a function that is invoked at the conclusion of
1878 ** each SQL statement that is run.
1879 */
1880 void *sqlite3_profile(
1881   sqlite3 *db,
1882   void (*xProfile)(void*,const char*,sqlite_uint64),
1883   void *pArg
1884 ){
1885   void *pOld;
1886 
1887 #ifdef SQLITE_ENABLE_API_ARMOR
1888   if( !sqlite3SafetyCheckOk(db) ){
1889     (void)SQLITE_MISUSE_BKPT;
1890     return 0;
1891   }
1892 #endif
1893   sqlite3_mutex_enter(db->mutex);
1894   pOld = db->pProfileArg;
1895   db->xProfile = xProfile;
1896   db->pProfileArg = pArg;
1897   sqlite3_mutex_leave(db->mutex);
1898   return pOld;
1899 }
1900 #endif /* SQLITE_OMIT_DEPRECATED */
1901 #endif /* SQLITE_OMIT_TRACE */
1902 
1903 /*
1904 ** Register a function to be invoked when a transaction commits.
1905 ** If the invoked function returns non-zero, then the commit becomes a
1906 ** rollback.
1907 */
1908 void *sqlite3_commit_hook(
1909   sqlite3 *db,              /* Attach the hook to this database */
1910   int (*xCallback)(void*),  /* Function to invoke on each commit */
1911   void *pArg                /* Argument to the function */
1912 ){
1913   void *pOld;
1914 
1915 #ifdef SQLITE_ENABLE_API_ARMOR
1916   if( !sqlite3SafetyCheckOk(db) ){
1917     (void)SQLITE_MISUSE_BKPT;
1918     return 0;
1919   }
1920 #endif
1921   sqlite3_mutex_enter(db->mutex);
1922   pOld = db->pCommitArg;
1923   db->xCommitCallback = xCallback;
1924   db->pCommitArg = pArg;
1925   sqlite3_mutex_leave(db->mutex);
1926   return pOld;
1927 }
1928 
1929 /*
1930 ** Register a callback to be invoked each time a row is updated,
1931 ** inserted or deleted using this database connection.
1932 */
1933 void *sqlite3_update_hook(
1934   sqlite3 *db,              /* Attach the hook to this database */
1935   void (*xCallback)(void*,int,char const *,char const *,sqlite_int64),
1936   void *pArg                /* Argument to the function */
1937 ){
1938   void *pRet;
1939 
1940 #ifdef SQLITE_ENABLE_API_ARMOR
1941   if( !sqlite3SafetyCheckOk(db) ){
1942     (void)SQLITE_MISUSE_BKPT;
1943     return 0;
1944   }
1945 #endif
1946   sqlite3_mutex_enter(db->mutex);
1947   pRet = db->pUpdateArg;
1948   db->xUpdateCallback = xCallback;
1949   db->pUpdateArg = pArg;
1950   sqlite3_mutex_leave(db->mutex);
1951   return pRet;
1952 }
1953 
1954 /*
1955 ** Register a callback to be invoked each time a transaction is rolled
1956 ** back by this database connection.
1957 */
1958 void *sqlite3_rollback_hook(
1959   sqlite3 *db,              /* Attach the hook to this database */
1960   void (*xCallback)(void*), /* Callback function */
1961   void *pArg                /* Argument to the function */
1962 ){
1963   void *pRet;
1964 
1965 #ifdef SQLITE_ENABLE_API_ARMOR
1966   if( !sqlite3SafetyCheckOk(db) ){
1967     (void)SQLITE_MISUSE_BKPT;
1968     return 0;
1969   }
1970 #endif
1971   sqlite3_mutex_enter(db->mutex);
1972   pRet = db->pRollbackArg;
1973   db->xRollbackCallback = xCallback;
1974   db->pRollbackArg = pArg;
1975   sqlite3_mutex_leave(db->mutex);
1976   return pRet;
1977 }
1978 
1979 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
1980 /*
1981 ** Register a callback to be invoked each time a row is updated,
1982 ** inserted or deleted using this database connection.
1983 */
1984 void *sqlite3_preupdate_hook(
1985   sqlite3 *db,              /* Attach the hook to this database */
1986   void(*xCallback)(         /* Callback function */
1987     void*,sqlite3*,int,char const*,char const*,sqlite3_int64,sqlite3_int64),
1988   void *pArg                /* First callback argument */
1989 ){
1990   void *pRet;
1991   sqlite3_mutex_enter(db->mutex);
1992   pRet = db->pPreUpdateArg;
1993   db->xPreUpdateCallback = xCallback;
1994   db->pPreUpdateArg = pArg;
1995   sqlite3_mutex_leave(db->mutex);
1996   return pRet;
1997 }
1998 #endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
1999 
2000 #ifndef SQLITE_OMIT_WAL
2001 /*
2002 ** The sqlite3_wal_hook() callback registered by sqlite3_wal_autocheckpoint().
2003 ** Invoke sqlite3_wal_checkpoint if the number of frames in the log file
2004 ** is greater than sqlite3.pWalArg cast to an integer (the value configured by
2005 ** wal_autocheckpoint()).
2006 */
2007 int sqlite3WalDefaultHook(
2008   void *pClientData,     /* Argument */
2009   sqlite3 *db,           /* Connection */
2010   const char *zDb,       /* Database */
2011   int nFrame             /* Size of WAL */
2012 ){
2013   if( nFrame>=SQLITE_PTR_TO_INT(pClientData) ){
2014     sqlite3BeginBenignMalloc();
2015     sqlite3_wal_checkpoint(db, zDb);
2016     sqlite3EndBenignMalloc();
2017   }
2018   return SQLITE_OK;
2019 }
2020 #endif /* SQLITE_OMIT_WAL */
2021 
2022 /*
2023 ** Configure an sqlite3_wal_hook() callback to automatically checkpoint
2024 ** a database after committing a transaction if there are nFrame or
2025 ** more frames in the log file. Passing zero or a negative value as the
2026 ** nFrame parameter disables automatic checkpoints entirely.
2027 **
2028 ** The callback registered by this function replaces any existing callback
2029 ** registered using sqlite3_wal_hook(). Likewise, registering a callback
2030 ** using sqlite3_wal_hook() disables the automatic checkpoint mechanism
2031 ** configured by this function.
2032 */
2033 int sqlite3_wal_autocheckpoint(sqlite3 *db, int nFrame){
2034 #ifdef SQLITE_OMIT_WAL
2035   UNUSED_PARAMETER(db);
2036   UNUSED_PARAMETER(nFrame);
2037 #else
2038 #ifdef SQLITE_ENABLE_API_ARMOR
2039   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
2040 #endif
2041   if( nFrame>0 ){
2042     sqlite3_wal_hook(db, sqlite3WalDefaultHook, SQLITE_INT_TO_PTR(nFrame));
2043   }else{
2044     sqlite3_wal_hook(db, 0, 0);
2045   }
2046 #endif
2047   return SQLITE_OK;
2048 }
2049 
2050 /*
2051 ** Register a callback to be invoked each time a transaction is written
2052 ** into the write-ahead-log by this database connection.
2053 */
2054 void *sqlite3_wal_hook(
2055   sqlite3 *db,                    /* Attach the hook to this db handle */
2056   int(*xCallback)(void *, sqlite3*, const char*, int),
2057   void *pArg                      /* First argument passed to xCallback() */
2058 ){
2059 #ifndef SQLITE_OMIT_WAL
2060   void *pRet;
2061 #ifdef SQLITE_ENABLE_API_ARMOR
2062   if( !sqlite3SafetyCheckOk(db) ){
2063     (void)SQLITE_MISUSE_BKPT;
2064     return 0;
2065   }
2066 #endif
2067   sqlite3_mutex_enter(db->mutex);
2068   pRet = db->pWalArg;
2069   db->xWalCallback = xCallback;
2070   db->pWalArg = pArg;
2071   sqlite3_mutex_leave(db->mutex);
2072   return pRet;
2073 #else
2074   return 0;
2075 #endif
2076 }
2077 
2078 /*
2079 ** Checkpoint database zDb.
2080 */
2081 int sqlite3_wal_checkpoint_v2(
2082   sqlite3 *db,                    /* Database handle */
2083   const char *zDb,                /* Name of attached database (or NULL) */
2084   int eMode,                      /* SQLITE_CHECKPOINT_* value */
2085   int *pnLog,                     /* OUT: Size of WAL log in frames */
2086   int *pnCkpt                     /* OUT: Total number of frames checkpointed */
2087 ){
2088 #ifdef SQLITE_OMIT_WAL
2089   return SQLITE_OK;
2090 #else
2091   int rc;                         /* Return code */
2092   int iDb = SQLITE_MAX_ATTACHED;  /* sqlite3.aDb[] index of db to checkpoint */
2093 
2094 #ifdef SQLITE_ENABLE_API_ARMOR
2095   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
2096 #endif
2097 
2098   /* Initialize the output variables to -1 in case an error occurs. */
2099   if( pnLog ) *pnLog = -1;
2100   if( pnCkpt ) *pnCkpt = -1;
2101 
2102   assert( SQLITE_CHECKPOINT_PASSIVE==0 );
2103   assert( SQLITE_CHECKPOINT_FULL==1 );
2104   assert( SQLITE_CHECKPOINT_RESTART==2 );
2105   assert( SQLITE_CHECKPOINT_TRUNCATE==3 );
2106   if( eMode<SQLITE_CHECKPOINT_PASSIVE || eMode>SQLITE_CHECKPOINT_TRUNCATE ){
2107     /* EVIDENCE-OF: R-03996-12088 The M parameter must be a valid checkpoint
2108     ** mode: */
2109     return SQLITE_MISUSE;
2110   }
2111 
2112   sqlite3_mutex_enter(db->mutex);
2113   if( zDb && zDb[0] ){
2114     iDb = sqlite3FindDbName(db, zDb);
2115   }
2116   if( iDb<0 ){
2117     rc = SQLITE_ERROR;
2118     sqlite3ErrorWithMsg(db, SQLITE_ERROR, "unknown database: %s", zDb);
2119   }else{
2120     db->busyHandler.nBusy = 0;
2121     rc = sqlite3Checkpoint(db, iDb, eMode, pnLog, pnCkpt);
2122     sqlite3Error(db, rc);
2123   }
2124   rc = sqlite3ApiExit(db, rc);
2125 
2126   /* If there are no active statements, clear the interrupt flag at this
2127   ** point.  */
2128   if( db->nVdbeActive==0 ){
2129     db->u1.isInterrupted = 0;
2130   }
2131 
2132   sqlite3_mutex_leave(db->mutex);
2133   return rc;
2134 #endif
2135 }
2136 
2137 
2138 /*
2139 ** Checkpoint database zDb. If zDb is NULL, or if the buffer zDb points
2140 ** to contains a zero-length string, all attached databases are
2141 ** checkpointed.
2142 */
2143 int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb){
2144   /* EVIDENCE-OF: R-41613-20553 The sqlite3_wal_checkpoint(D,X) is equivalent to
2145   ** sqlite3_wal_checkpoint_v2(D,X,SQLITE_CHECKPOINT_PASSIVE,0,0). */
2146   return sqlite3_wal_checkpoint_v2(db,zDb,SQLITE_CHECKPOINT_PASSIVE,0,0);
2147 }
2148 
2149 #ifndef SQLITE_OMIT_WAL
2150 /*
2151 ** Run a checkpoint on database iDb. This is a no-op if database iDb is
2152 ** not currently open in WAL mode.
2153 **
2154 ** If a transaction is open on the database being checkpointed, this
2155 ** function returns SQLITE_LOCKED and a checkpoint is not attempted. If
2156 ** an error occurs while running the checkpoint, an SQLite error code is
2157 ** returned (i.e. SQLITE_IOERR). Otherwise, SQLITE_OK.
2158 **
2159 ** The mutex on database handle db should be held by the caller. The mutex
2160 ** associated with the specific b-tree being checkpointed is taken by
2161 ** this function while the checkpoint is running.
2162 **
2163 ** If iDb is passed SQLITE_MAX_ATTACHED, then all attached databases are
2164 ** checkpointed. If an error is encountered it is returned immediately -
2165 ** no attempt is made to checkpoint any remaining databases.
2166 **
2167 ** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
2168 */
2169 int sqlite3Checkpoint(sqlite3 *db, int iDb, int eMode, int *pnLog, int *pnCkpt){
2170   int rc = SQLITE_OK;             /* Return code */
2171   int i;                          /* Used to iterate through attached dbs */
2172   int bBusy = 0;                  /* True if SQLITE_BUSY has been encountered */
2173 
2174   assert( sqlite3_mutex_held(db->mutex) );
2175   assert( !pnLog || *pnLog==-1 );
2176   assert( !pnCkpt || *pnCkpt==-1 );
2177 
2178   for(i=0; i<db->nDb && rc==SQLITE_OK; i++){
2179     if( i==iDb || iDb==SQLITE_MAX_ATTACHED ){
2180       rc = sqlite3BtreeCheckpoint(db->aDb[i].pBt, eMode, pnLog, pnCkpt);
2181       pnLog = 0;
2182       pnCkpt = 0;
2183       if( rc==SQLITE_BUSY ){
2184         bBusy = 1;
2185         rc = SQLITE_OK;
2186       }
2187     }
2188   }
2189 
2190   return (rc==SQLITE_OK && bBusy) ? SQLITE_BUSY : rc;
2191 }
2192 #endif /* SQLITE_OMIT_WAL */
2193 
2194 /*
2195 ** This function returns true if main-memory should be used instead of
2196 ** a temporary file for transient pager files and statement journals.
2197 ** The value returned depends on the value of db->temp_store (runtime
2198 ** parameter) and the compile time value of SQLITE_TEMP_STORE. The
2199 ** following table describes the relationship between these two values
2200 ** and this functions return value.
2201 **
2202 **   SQLITE_TEMP_STORE     db->temp_store     Location of temporary database
2203 **   -----------------     --------------     ------------------------------
2204 **   0                     any                file      (return 0)
2205 **   1                     1                  file      (return 0)
2206 **   1                     2                  memory    (return 1)
2207 **   1                     0                  file      (return 0)
2208 **   2                     1                  file      (return 0)
2209 **   2                     2                  memory    (return 1)
2210 **   2                     0                  memory    (return 1)
2211 **   3                     any                memory    (return 1)
2212 */
2213 int sqlite3TempInMemory(const sqlite3 *db){
2214 #if SQLITE_TEMP_STORE==1
2215   return ( db->temp_store==2 );
2216 #endif
2217 #if SQLITE_TEMP_STORE==2
2218   return ( db->temp_store!=1 );
2219 #endif
2220 #if SQLITE_TEMP_STORE==3
2221   UNUSED_PARAMETER(db);
2222   return 1;
2223 #endif
2224 #if SQLITE_TEMP_STORE<1 || SQLITE_TEMP_STORE>3
2225   UNUSED_PARAMETER(db);
2226   return 0;
2227 #endif
2228 }
2229 
2230 /*
2231 ** Return UTF-8 encoded English language explanation of the most recent
2232 ** error.
2233 */
2234 const char *sqlite3_errmsg(sqlite3 *db){
2235   const char *z;
2236   if( !db ){
2237     return sqlite3ErrStr(SQLITE_NOMEM_BKPT);
2238   }
2239   if( !sqlite3SafetyCheckSickOrOk(db) ){
2240     return sqlite3ErrStr(SQLITE_MISUSE_BKPT);
2241   }
2242   sqlite3_mutex_enter(db->mutex);
2243   if( db->mallocFailed ){
2244     z = sqlite3ErrStr(SQLITE_NOMEM_BKPT);
2245   }else{
2246     testcase( db->pErr==0 );
2247     z = (char*)sqlite3_value_text(db->pErr);
2248     assert( !db->mallocFailed );
2249     if( z==0 ){
2250       z = sqlite3ErrStr(db->errCode);
2251     }
2252   }
2253   sqlite3_mutex_leave(db->mutex);
2254   return z;
2255 }
2256 
2257 #ifndef SQLITE_OMIT_UTF16
2258 /*
2259 ** Return UTF-16 encoded English language explanation of the most recent
2260 ** error.
2261 */
2262 const void *sqlite3_errmsg16(sqlite3 *db){
2263   static const u16 outOfMem[] = {
2264     'o', 'u', 't', ' ', 'o', 'f', ' ', 'm', 'e', 'm', 'o', 'r', 'y', 0
2265   };
2266   static const u16 misuse[] = {
2267     'l', 'i', 'b', 'r', 'a', 'r', 'y', ' ',
2268     'r', 'o', 'u', 't', 'i', 'n', 'e', ' ',
2269     'c', 'a', 'l', 'l', 'e', 'd', ' ',
2270     'o', 'u', 't', ' ',
2271     'o', 'f', ' ',
2272     's', 'e', 'q', 'u', 'e', 'n', 'c', 'e', 0
2273   };
2274 
2275   const void *z;
2276   if( !db ){
2277     return (void *)outOfMem;
2278   }
2279   if( !sqlite3SafetyCheckSickOrOk(db) ){
2280     return (void *)misuse;
2281   }
2282   sqlite3_mutex_enter(db->mutex);
2283   if( db->mallocFailed ){
2284     z = (void *)outOfMem;
2285   }else{
2286     z = sqlite3_value_text16(db->pErr);
2287     if( z==0 ){
2288       sqlite3ErrorWithMsg(db, db->errCode, sqlite3ErrStr(db->errCode));
2289       z = sqlite3_value_text16(db->pErr);
2290     }
2291     /* A malloc() may have failed within the call to sqlite3_value_text16()
2292     ** above. If this is the case, then the db->mallocFailed flag needs to
2293     ** be cleared before returning. Do this directly, instead of via
2294     ** sqlite3ApiExit(), to avoid setting the database handle error message.
2295     */
2296     sqlite3OomClear(db);
2297   }
2298   sqlite3_mutex_leave(db->mutex);
2299   return z;
2300 }
2301 #endif /* SQLITE_OMIT_UTF16 */
2302 
2303 /*
2304 ** Return the most recent error code generated by an SQLite routine. If NULL is
2305 ** passed to this function, we assume a malloc() failed during sqlite3_open().
2306 */
2307 int sqlite3_errcode(sqlite3 *db){
2308   if( db && !sqlite3SafetyCheckSickOrOk(db) ){
2309     return SQLITE_MISUSE_BKPT;
2310   }
2311   if( !db || db->mallocFailed ){
2312     return SQLITE_NOMEM_BKPT;
2313   }
2314   return db->errCode & db->errMask;
2315 }
2316 int sqlite3_extended_errcode(sqlite3 *db){
2317   if( db && !sqlite3SafetyCheckSickOrOk(db) ){
2318     return SQLITE_MISUSE_BKPT;
2319   }
2320   if( !db || db->mallocFailed ){
2321     return SQLITE_NOMEM_BKPT;
2322   }
2323   return db->errCode;
2324 }
2325 int sqlite3_system_errno(sqlite3 *db){
2326   return db ? db->iSysErrno : 0;
2327 }
2328 
2329 /*
2330 ** Return a string that describes the kind of error specified in the
2331 ** argument.  For now, this simply calls the internal sqlite3ErrStr()
2332 ** function.
2333 */
2334 const char *sqlite3_errstr(int rc){
2335   return sqlite3ErrStr(rc);
2336 }
2337 
2338 /*
2339 ** Create a new collating function for database "db".  The name is zName
2340 ** and the encoding is enc.
2341 */
2342 static int createCollation(
2343   sqlite3* db,
2344   const char *zName,
2345   u8 enc,
2346   void* pCtx,
2347   int(*xCompare)(void*,int,const void*,int,const void*),
2348   void(*xDel)(void*)
2349 ){
2350   CollSeq *pColl;
2351   int enc2;
2352 
2353   assert( sqlite3_mutex_held(db->mutex) );
2354 
2355   /* If SQLITE_UTF16 is specified as the encoding type, transform this
2356   ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
2357   ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
2358   */
2359   enc2 = enc;
2360   testcase( enc2==SQLITE_UTF16 );
2361   testcase( enc2==SQLITE_UTF16_ALIGNED );
2362   if( enc2==SQLITE_UTF16 || enc2==SQLITE_UTF16_ALIGNED ){
2363     enc2 = SQLITE_UTF16NATIVE;
2364   }
2365   if( enc2<SQLITE_UTF8 || enc2>SQLITE_UTF16BE ){
2366     return SQLITE_MISUSE_BKPT;
2367   }
2368 
2369   /* Check if this call is removing or replacing an existing collation
2370   ** sequence. If so, and there are active VMs, return busy. If there
2371   ** are no active VMs, invalidate any pre-compiled statements.
2372   */
2373   pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 0);
2374   if( pColl && pColl->xCmp ){
2375     if( db->nVdbeActive ){
2376       sqlite3ErrorWithMsg(db, SQLITE_BUSY,
2377         "unable to delete/modify collation sequence due to active statements");
2378       return SQLITE_BUSY;
2379     }
2380     sqlite3ExpirePreparedStatements(db);
2381 
2382     /* If collation sequence pColl was created directly by a call to
2383     ** sqlite3_create_collation, and not generated by synthCollSeq(),
2384     ** then any copies made by synthCollSeq() need to be invalidated.
2385     ** Also, collation destructor - CollSeq.xDel() - function may need
2386     ** to be called.
2387     */
2388     if( (pColl->enc & ~SQLITE_UTF16_ALIGNED)==enc2 ){
2389       CollSeq *aColl = sqlite3HashFind(&db->aCollSeq, zName);
2390       int j;
2391       for(j=0; j<3; j++){
2392         CollSeq *p = &aColl[j];
2393         if( p->enc==pColl->enc ){
2394           if( p->xDel ){
2395             p->xDel(p->pUser);
2396           }
2397           p->xCmp = 0;
2398         }
2399       }
2400     }
2401   }
2402 
2403   pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, 1);
2404   if( pColl==0 ) return SQLITE_NOMEM_BKPT;
2405   pColl->xCmp = xCompare;
2406   pColl->pUser = pCtx;
2407   pColl->xDel = xDel;
2408   pColl->enc = (u8)(enc2 | (enc & SQLITE_UTF16_ALIGNED));
2409   sqlite3Error(db, SQLITE_OK);
2410   return SQLITE_OK;
2411 }
2412 
2413 
2414 /*
2415 ** This array defines hard upper bounds on limit values.  The
2416 ** initializer must be kept in sync with the SQLITE_LIMIT_*
2417 ** #defines in sqlite3.h.
2418 */
2419 static const int aHardLimit[] = {
2420   SQLITE_MAX_LENGTH,
2421   SQLITE_MAX_SQL_LENGTH,
2422   SQLITE_MAX_COLUMN,
2423   SQLITE_MAX_EXPR_DEPTH,
2424   SQLITE_MAX_COMPOUND_SELECT,
2425   SQLITE_MAX_VDBE_OP,
2426   SQLITE_MAX_FUNCTION_ARG,
2427   SQLITE_MAX_ATTACHED,
2428   SQLITE_MAX_LIKE_PATTERN_LENGTH,
2429   SQLITE_MAX_VARIABLE_NUMBER,      /* IMP: R-38091-32352 */
2430   SQLITE_MAX_TRIGGER_DEPTH,
2431   SQLITE_MAX_WORKER_THREADS,
2432 };
2433 
2434 /*
2435 ** Make sure the hard limits are set to reasonable values
2436 */
2437 #if SQLITE_MAX_LENGTH<100
2438 # error SQLITE_MAX_LENGTH must be at least 100
2439 #endif
2440 #if SQLITE_MAX_SQL_LENGTH<100
2441 # error SQLITE_MAX_SQL_LENGTH must be at least 100
2442 #endif
2443 #if SQLITE_MAX_SQL_LENGTH>SQLITE_MAX_LENGTH
2444 # error SQLITE_MAX_SQL_LENGTH must not be greater than SQLITE_MAX_LENGTH
2445 #endif
2446 #if SQLITE_MAX_COMPOUND_SELECT<2
2447 # error SQLITE_MAX_COMPOUND_SELECT must be at least 2
2448 #endif
2449 #if SQLITE_MAX_VDBE_OP<40
2450 # error SQLITE_MAX_VDBE_OP must be at least 40
2451 #endif
2452 #if SQLITE_MAX_FUNCTION_ARG<0 || SQLITE_MAX_FUNCTION_ARG>127
2453 # error SQLITE_MAX_FUNCTION_ARG must be between 0 and 127
2454 #endif
2455 #if SQLITE_MAX_ATTACHED<0 || SQLITE_MAX_ATTACHED>125
2456 # error SQLITE_MAX_ATTACHED must be between 0 and 125
2457 #endif
2458 #if SQLITE_MAX_LIKE_PATTERN_LENGTH<1
2459 # error SQLITE_MAX_LIKE_PATTERN_LENGTH must be at least 1
2460 #endif
2461 #if SQLITE_MAX_COLUMN>32767
2462 # error SQLITE_MAX_COLUMN must not exceed 32767
2463 #endif
2464 #if SQLITE_MAX_TRIGGER_DEPTH<1
2465 # error SQLITE_MAX_TRIGGER_DEPTH must be at least 1
2466 #endif
2467 #if SQLITE_MAX_WORKER_THREADS<0 || SQLITE_MAX_WORKER_THREADS>50
2468 # error SQLITE_MAX_WORKER_THREADS must be between 0 and 50
2469 #endif
2470 
2471 
2472 /*
2473 ** Change the value of a limit.  Report the old value.
2474 ** If an invalid limit index is supplied, report -1.
2475 ** Make no changes but still report the old value if the
2476 ** new limit is negative.
2477 **
2478 ** A new lower limit does not shrink existing constructs.
2479 ** It merely prevents new constructs that exceed the limit
2480 ** from forming.
2481 */
2482 int sqlite3_limit(sqlite3 *db, int limitId, int newLimit){
2483   int oldLimit;
2484 
2485 #ifdef SQLITE_ENABLE_API_ARMOR
2486   if( !sqlite3SafetyCheckOk(db) ){
2487     (void)SQLITE_MISUSE_BKPT;
2488     return -1;
2489   }
2490 #endif
2491 
2492   /* EVIDENCE-OF: R-30189-54097 For each limit category SQLITE_LIMIT_NAME
2493   ** there is a hard upper bound set at compile-time by a C preprocessor
2494   ** macro called SQLITE_MAX_NAME. (The "_LIMIT_" in the name is changed to
2495   ** "_MAX_".)
2496   */
2497   assert( aHardLimit[SQLITE_LIMIT_LENGTH]==SQLITE_MAX_LENGTH );
2498   assert( aHardLimit[SQLITE_LIMIT_SQL_LENGTH]==SQLITE_MAX_SQL_LENGTH );
2499   assert( aHardLimit[SQLITE_LIMIT_COLUMN]==SQLITE_MAX_COLUMN );
2500   assert( aHardLimit[SQLITE_LIMIT_EXPR_DEPTH]==SQLITE_MAX_EXPR_DEPTH );
2501   assert( aHardLimit[SQLITE_LIMIT_COMPOUND_SELECT]==SQLITE_MAX_COMPOUND_SELECT);
2502   assert( aHardLimit[SQLITE_LIMIT_VDBE_OP]==SQLITE_MAX_VDBE_OP );
2503   assert( aHardLimit[SQLITE_LIMIT_FUNCTION_ARG]==SQLITE_MAX_FUNCTION_ARG );
2504   assert( aHardLimit[SQLITE_LIMIT_ATTACHED]==SQLITE_MAX_ATTACHED );
2505   assert( aHardLimit[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]==
2506                                                SQLITE_MAX_LIKE_PATTERN_LENGTH );
2507   assert( aHardLimit[SQLITE_LIMIT_VARIABLE_NUMBER]==SQLITE_MAX_VARIABLE_NUMBER);
2508   assert( aHardLimit[SQLITE_LIMIT_TRIGGER_DEPTH]==SQLITE_MAX_TRIGGER_DEPTH );
2509   assert( aHardLimit[SQLITE_LIMIT_WORKER_THREADS]==SQLITE_MAX_WORKER_THREADS );
2510   assert( SQLITE_LIMIT_WORKER_THREADS==(SQLITE_N_LIMIT-1) );
2511 
2512 
2513   if( limitId<0 || limitId>=SQLITE_N_LIMIT ){
2514     return -1;
2515   }
2516   oldLimit = db->aLimit[limitId];
2517   if( newLimit>=0 ){                   /* IMP: R-52476-28732 */
2518     if( newLimit>aHardLimit[limitId] ){
2519       newLimit = aHardLimit[limitId];  /* IMP: R-51463-25634 */
2520     }
2521     db->aLimit[limitId] = newLimit;
2522   }
2523   return oldLimit;                     /* IMP: R-53341-35419 */
2524 }
2525 
2526 /*
2527 ** This function is used to parse both URIs and non-URI filenames passed by the
2528 ** user to API functions sqlite3_open() or sqlite3_open_v2(), and for database
2529 ** URIs specified as part of ATTACH statements.
2530 **
2531 ** The first argument to this function is the name of the VFS to use (or
2532 ** a NULL to signify the default VFS) if the URI does not contain a "vfs=xxx"
2533 ** query parameter. The second argument contains the URI (or non-URI filename)
2534 ** itself. When this function is called the *pFlags variable should contain
2535 ** the default flags to open the database handle with. The value stored in
2536 ** *pFlags may be updated before returning if the URI filename contains
2537 ** "cache=xxx" or "mode=xxx" query parameters.
2538 **
2539 ** If successful, SQLITE_OK is returned. In this case *ppVfs is set to point to
2540 ** the VFS that should be used to open the database file. *pzFile is set to
2541 ** point to a buffer containing the name of the file to open. It is the
2542 ** responsibility of the caller to eventually call sqlite3_free() to release
2543 ** this buffer.
2544 **
2545 ** If an error occurs, then an SQLite error code is returned and *pzErrMsg
2546 ** may be set to point to a buffer containing an English language error
2547 ** message. It is the responsibility of the caller to eventually release
2548 ** this buffer by calling sqlite3_free().
2549 */
2550 int sqlite3ParseUri(
2551   const char *zDefaultVfs,        /* VFS to use if no "vfs=xxx" query option */
2552   const char *zUri,               /* Nul-terminated URI to parse */
2553   unsigned int *pFlags,           /* IN/OUT: SQLITE_OPEN_XXX flags */
2554   sqlite3_vfs **ppVfs,            /* OUT: VFS to use */
2555   char **pzFile,                  /* OUT: Filename component of URI */
2556   char **pzErrMsg                 /* OUT: Error message (if rc!=SQLITE_OK) */
2557 ){
2558   int rc = SQLITE_OK;
2559   unsigned int flags = *pFlags;
2560   const char *zVfs = zDefaultVfs;
2561   char *zFile;
2562   char c;
2563   int nUri = sqlite3Strlen30(zUri);
2564 
2565   assert( *pzErrMsg==0 );
2566 
2567   if( ((flags & SQLITE_OPEN_URI)             /* IMP: R-48725-32206 */
2568             || sqlite3GlobalConfig.bOpenUri) /* IMP: R-51689-46548 */
2569    && nUri>=5 && memcmp(zUri, "file:", 5)==0 /* IMP: R-57884-37496 */
2570   ){
2571     char *zOpt;
2572     int eState;                   /* Parser state when parsing URI */
2573     int iIn;                      /* Input character index */
2574     int iOut = 0;                 /* Output character index */
2575     u64 nByte = nUri+2;           /* Bytes of space to allocate */
2576 
2577     /* Make sure the SQLITE_OPEN_URI flag is set to indicate to the VFS xOpen
2578     ** method that there may be extra parameters following the file-name.  */
2579     flags |= SQLITE_OPEN_URI;
2580 
2581     for(iIn=0; iIn<nUri; iIn++) nByte += (zUri[iIn]=='&');
2582     zFile = sqlite3_malloc64(nByte);
2583     if( !zFile ) return SQLITE_NOMEM_BKPT;
2584 
2585     iIn = 5;
2586 #ifdef SQLITE_ALLOW_URI_AUTHORITY
2587     if( strncmp(zUri+5, "///", 3)==0 ){
2588       iIn = 7;
2589       /* The following condition causes URIs with five leading / characters
2590       ** like file://///host/path to be converted into UNCs like //host/path.
2591       ** The correct URI for that UNC has only two or four leading / characters
2592       ** file://host/path or file:////host/path.  But 5 leading slashes is a
2593       ** common error, we are told, so we handle it as a special case. */
2594       if( strncmp(zUri+7, "///", 3)==0 ){ iIn++; }
2595     }else if( strncmp(zUri+5, "//localhost/", 12)==0 ){
2596       iIn = 16;
2597     }
2598 #else
2599     /* Discard the scheme and authority segments of the URI. */
2600     if( zUri[5]=='/' && zUri[6]=='/' ){
2601       iIn = 7;
2602       while( zUri[iIn] && zUri[iIn]!='/' ) iIn++;
2603       if( iIn!=7 && (iIn!=16 || memcmp("localhost", &zUri[7], 9)) ){
2604         *pzErrMsg = sqlite3_mprintf("invalid uri authority: %.*s",
2605             iIn-7, &zUri[7]);
2606         rc = SQLITE_ERROR;
2607         goto parse_uri_out;
2608       }
2609     }
2610 #endif
2611 
2612     /* Copy the filename and any query parameters into the zFile buffer.
2613     ** Decode %HH escape codes along the way.
2614     **
2615     ** Within this loop, variable eState may be set to 0, 1 or 2, depending
2616     ** on the parsing context. As follows:
2617     **
2618     **   0: Parsing file-name.
2619     **   1: Parsing name section of a name=value query parameter.
2620     **   2: Parsing value section of a name=value query parameter.
2621     */
2622     eState = 0;
2623     while( (c = zUri[iIn])!=0 && c!='#' ){
2624       iIn++;
2625       if( c=='%'
2626        && sqlite3Isxdigit(zUri[iIn])
2627        && sqlite3Isxdigit(zUri[iIn+1])
2628       ){
2629         int octet = (sqlite3HexToInt(zUri[iIn++]) << 4);
2630         octet += sqlite3HexToInt(zUri[iIn++]);
2631 
2632         assert( octet>=0 && octet<256 );
2633         if( octet==0 ){
2634 #ifndef SQLITE_ENABLE_URI_00_ERROR
2635           /* This branch is taken when "%00" appears within the URI. In this
2636           ** case we ignore all text in the remainder of the path, name or
2637           ** value currently being parsed. So ignore the current character
2638           ** and skip to the next "?", "=" or "&", as appropriate. */
2639           while( (c = zUri[iIn])!=0 && c!='#'
2640               && (eState!=0 || c!='?')
2641               && (eState!=1 || (c!='=' && c!='&'))
2642               && (eState!=2 || c!='&')
2643           ){
2644             iIn++;
2645           }
2646           continue;
2647 #else
2648           /* If ENABLE_URI_00_ERROR is defined, "%00" in a URI is an error. */
2649           *pzErrMsg = sqlite3_mprintf("unexpected %%00 in uri");
2650           rc = SQLITE_ERROR;
2651           goto parse_uri_out;
2652 #endif
2653         }
2654         c = octet;
2655       }else if( eState==1 && (c=='&' || c=='=') ){
2656         if( zFile[iOut-1]==0 ){
2657           /* An empty option name. Ignore this option altogether. */
2658           while( zUri[iIn] && zUri[iIn]!='#' && zUri[iIn-1]!='&' ) iIn++;
2659           continue;
2660         }
2661         if( c=='&' ){
2662           zFile[iOut++] = '\0';
2663         }else{
2664           eState = 2;
2665         }
2666         c = 0;
2667       }else if( (eState==0 && c=='?') || (eState==2 && c=='&') ){
2668         c = 0;
2669         eState = 1;
2670       }
2671       zFile[iOut++] = c;
2672     }
2673     if( eState==1 ) zFile[iOut++] = '\0';
2674     zFile[iOut++] = '\0';
2675     zFile[iOut++] = '\0';
2676 
2677     /* Check if there were any options specified that should be interpreted
2678     ** here. Options that are interpreted here include "vfs" and those that
2679     ** correspond to flags that may be passed to the sqlite3_open_v2()
2680     ** method. */
2681     zOpt = &zFile[sqlite3Strlen30(zFile)+1];
2682     while( zOpt[0] ){
2683       int nOpt = sqlite3Strlen30(zOpt);
2684       char *zVal = &zOpt[nOpt+1];
2685       int nVal = sqlite3Strlen30(zVal);
2686 
2687       if( nOpt==3 && memcmp("vfs", zOpt, 3)==0 ){
2688         zVfs = zVal;
2689       }else{
2690         struct OpenMode {
2691           const char *z;
2692           int mode;
2693         } *aMode = 0;
2694         char *zModeType = 0;
2695         int mask = 0;
2696         int limit = 0;
2697 
2698         if( nOpt==5 && memcmp("cache", zOpt, 5)==0 ){
2699           static struct OpenMode aCacheMode[] = {
2700             { "shared",  SQLITE_OPEN_SHAREDCACHE },
2701             { "private", SQLITE_OPEN_PRIVATECACHE },
2702             { 0, 0 }
2703           };
2704 
2705           mask = SQLITE_OPEN_SHAREDCACHE|SQLITE_OPEN_PRIVATECACHE;
2706           aMode = aCacheMode;
2707           limit = mask;
2708           zModeType = "cache";
2709         }
2710         if( nOpt==4 && memcmp("mode", zOpt, 4)==0 ){
2711           static struct OpenMode aOpenMode[] = {
2712             { "ro",  SQLITE_OPEN_READONLY },
2713             { "rw",  SQLITE_OPEN_READWRITE },
2714             { "rwc", SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE },
2715             { "memory", SQLITE_OPEN_MEMORY },
2716             { 0, 0 }
2717           };
2718 
2719           mask = SQLITE_OPEN_READONLY | SQLITE_OPEN_READWRITE
2720                    | SQLITE_OPEN_CREATE | SQLITE_OPEN_MEMORY;
2721           aMode = aOpenMode;
2722           limit = mask & flags;
2723           zModeType = "access";
2724         }
2725 
2726         if( aMode ){
2727           int i;
2728           int mode = 0;
2729           for(i=0; aMode[i].z; i++){
2730             const char *z = aMode[i].z;
2731             if( nVal==sqlite3Strlen30(z) && 0==memcmp(zVal, z, nVal) ){
2732               mode = aMode[i].mode;
2733               break;
2734             }
2735           }
2736           if( mode==0 ){
2737             *pzErrMsg = sqlite3_mprintf("no such %s mode: %s", zModeType, zVal);
2738             rc = SQLITE_ERROR;
2739             goto parse_uri_out;
2740           }
2741           if( (mode & ~SQLITE_OPEN_MEMORY)>limit ){
2742             *pzErrMsg = sqlite3_mprintf("%s mode not allowed: %s",
2743                                         zModeType, zVal);
2744             rc = SQLITE_PERM;
2745             goto parse_uri_out;
2746           }
2747           flags = (flags & ~mask) | mode;
2748         }
2749       }
2750 
2751       zOpt = &zVal[nVal+1];
2752     }
2753 
2754   }else{
2755     zFile = sqlite3_malloc64(nUri+2);
2756     if( !zFile ) return SQLITE_NOMEM_BKPT;
2757     if( nUri ){
2758       memcpy(zFile, zUri, nUri);
2759     }
2760     zFile[nUri] = '\0';
2761     zFile[nUri+1] = '\0';
2762     flags &= ~SQLITE_OPEN_URI;
2763   }
2764 
2765   *ppVfs = sqlite3_vfs_find(zVfs);
2766   if( *ppVfs==0 ){
2767     *pzErrMsg = sqlite3_mprintf("no such vfs: %s", zVfs);
2768     rc = SQLITE_ERROR;
2769   }
2770  parse_uri_out:
2771   if( rc!=SQLITE_OK ){
2772     sqlite3_free(zFile);
2773     zFile = 0;
2774   }
2775   *pFlags = flags;
2776   *pzFile = zFile;
2777   return rc;
2778 }
2779 
2780 
2781 /*
2782 ** This routine does the work of opening a database on behalf of
2783 ** sqlite3_open() and sqlite3_open16(). The database filename "zFilename"
2784 ** is UTF-8 encoded.
2785 */
2786 static int openDatabase(
2787   const char *zFilename, /* Database filename UTF-8 encoded */
2788   sqlite3 **ppDb,        /* OUT: Returned database handle */
2789   unsigned int flags,    /* Operational flags */
2790   const char *zVfs       /* Name of the VFS to use */
2791 ){
2792   sqlite3 *db;                    /* Store allocated handle here */
2793   int rc;                         /* Return code */
2794   int isThreadsafe;               /* True for threadsafe connections */
2795   char *zOpen = 0;                /* Filename argument to pass to BtreeOpen() */
2796   char *zErrMsg = 0;              /* Error message from sqlite3ParseUri() */
2797 
2798 #ifdef SQLITE_ENABLE_API_ARMOR
2799   if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
2800 #endif
2801   *ppDb = 0;
2802 #ifndef SQLITE_OMIT_AUTOINIT
2803   rc = sqlite3_initialize();
2804   if( rc ) return rc;
2805 #endif
2806 
2807   /* Only allow sensible combinations of bits in the flags argument.
2808   ** Throw an error if any non-sense combination is used.  If we
2809   ** do not block illegal combinations here, it could trigger
2810   ** assert() statements in deeper layers.  Sensible combinations
2811   ** are:
2812   **
2813   **  1:  SQLITE_OPEN_READONLY
2814   **  2:  SQLITE_OPEN_READWRITE
2815   **  6:  SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE
2816   */
2817   assert( SQLITE_OPEN_READONLY  == 0x01 );
2818   assert( SQLITE_OPEN_READWRITE == 0x02 );
2819   assert( SQLITE_OPEN_CREATE    == 0x04 );
2820   testcase( (1<<(flags&7))==0x02 ); /* READONLY */
2821   testcase( (1<<(flags&7))==0x04 ); /* READWRITE */
2822   testcase( (1<<(flags&7))==0x40 ); /* READWRITE | CREATE */
2823   if( ((1<<(flags&7)) & 0x46)==0 ){
2824     return SQLITE_MISUSE_BKPT;  /* IMP: R-65497-44594 */
2825   }
2826 
2827   if( sqlite3GlobalConfig.bCoreMutex==0 ){
2828     isThreadsafe = 0;
2829   }else if( flags & SQLITE_OPEN_NOMUTEX ){
2830     isThreadsafe = 0;
2831   }else if( flags & SQLITE_OPEN_FULLMUTEX ){
2832     isThreadsafe = 1;
2833   }else{
2834     isThreadsafe = sqlite3GlobalConfig.bFullMutex;
2835   }
2836   if( flags & SQLITE_OPEN_PRIVATECACHE ){
2837     flags &= ~SQLITE_OPEN_SHAREDCACHE;
2838   }else if( sqlite3GlobalConfig.sharedCacheEnabled ){
2839     flags |= SQLITE_OPEN_SHAREDCACHE;
2840   }
2841 
2842   /* Remove harmful bits from the flags parameter
2843   **
2844   ** The SQLITE_OPEN_NOMUTEX and SQLITE_OPEN_FULLMUTEX flags were
2845   ** dealt with in the previous code block.  Besides these, the only
2846   ** valid input flags for sqlite3_open_v2() are SQLITE_OPEN_READONLY,
2847   ** SQLITE_OPEN_READWRITE, SQLITE_OPEN_CREATE, SQLITE_OPEN_SHAREDCACHE,
2848   ** SQLITE_OPEN_PRIVATECACHE, and some reserved bits.  Silently mask
2849   ** off all other flags.
2850   */
2851   flags &=  ~( SQLITE_OPEN_DELETEONCLOSE |
2852                SQLITE_OPEN_EXCLUSIVE |
2853                SQLITE_OPEN_MAIN_DB |
2854                SQLITE_OPEN_TEMP_DB |
2855                SQLITE_OPEN_TRANSIENT_DB |
2856                SQLITE_OPEN_MAIN_JOURNAL |
2857                SQLITE_OPEN_TEMP_JOURNAL |
2858                SQLITE_OPEN_SUBJOURNAL |
2859                SQLITE_OPEN_MASTER_JOURNAL |
2860                SQLITE_OPEN_NOMUTEX |
2861                SQLITE_OPEN_FULLMUTEX |
2862                SQLITE_OPEN_WAL
2863              );
2864 
2865   /* Allocate the sqlite data structure */
2866   db = sqlite3MallocZero( sizeof(sqlite3) );
2867   if( db==0 ) goto opendb_out;
2868   if( isThreadsafe ){
2869     db->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
2870     if( db->mutex==0 ){
2871       sqlite3_free(db);
2872       db = 0;
2873       goto opendb_out;
2874     }
2875   }
2876   sqlite3_mutex_enter(db->mutex);
2877   db->errMask = 0xff;
2878   db->nDb = 2;
2879   db->magic = SQLITE_MAGIC_BUSY;
2880   db->aDb = db->aDbStatic;
2881 
2882   assert( sizeof(db->aLimit)==sizeof(aHardLimit) );
2883   memcpy(db->aLimit, aHardLimit, sizeof(db->aLimit));
2884   db->aLimit[SQLITE_LIMIT_WORKER_THREADS] = SQLITE_DEFAULT_WORKER_THREADS;
2885   db->autoCommit = 1;
2886   db->nextAutovac = -1;
2887   db->szMmap = sqlite3GlobalConfig.szMmap;
2888   db->nextPagesize = 0;
2889   db->nMaxSorterMmap = 0x7FFFFFFF;
2890   db->flags |= SQLITE_ShortColNames | SQLITE_EnableTrigger | SQLITE_CacheSpill
2891 #if !defined(SQLITE_DEFAULT_AUTOMATIC_INDEX) || SQLITE_DEFAULT_AUTOMATIC_INDEX
2892                  | SQLITE_AutoIndex
2893 #endif
2894 #if SQLITE_DEFAULT_CKPTFULLFSYNC
2895                  | SQLITE_CkptFullFSync
2896 #endif
2897 #if SQLITE_DEFAULT_FILE_FORMAT<4
2898                  | SQLITE_LegacyFileFmt
2899 #endif
2900 #ifdef SQLITE_ENABLE_LOAD_EXTENSION
2901                  | SQLITE_LoadExtension
2902 #endif
2903 #if SQLITE_DEFAULT_RECURSIVE_TRIGGERS
2904                  | SQLITE_RecTriggers
2905 #endif
2906 #if defined(SQLITE_DEFAULT_FOREIGN_KEYS) && SQLITE_DEFAULT_FOREIGN_KEYS
2907                  | SQLITE_ForeignKeys
2908 #endif
2909 #if defined(SQLITE_REVERSE_UNORDERED_SELECTS)
2910                  | SQLITE_ReverseOrder
2911 #endif
2912 #if defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
2913                  | SQLITE_CellSizeCk
2914 #endif
2915 #if defined(SQLITE_ENABLE_FTS3_TOKENIZER)
2916                  | SQLITE_Fts3Tokenizer
2917 #endif
2918       ;
2919   sqlite3HashInit(&db->aCollSeq);
2920 #ifndef SQLITE_OMIT_VIRTUALTABLE
2921   sqlite3HashInit(&db->aModule);
2922 #endif
2923 
2924   /* Add the default collation sequence BINARY. BINARY works for both UTF-8
2925   ** and UTF-16, so add a version for each to avoid any unnecessary
2926   ** conversions. The only error that can occur here is a malloc() failure.
2927   **
2928   ** EVIDENCE-OF: R-52786-44878 SQLite defines three built-in collating
2929   ** functions:
2930   */
2931   createCollation(db, sqlite3StrBINARY, SQLITE_UTF8, 0, binCollFunc, 0);
2932   createCollation(db, sqlite3StrBINARY, SQLITE_UTF16BE, 0, binCollFunc, 0);
2933   createCollation(db, sqlite3StrBINARY, SQLITE_UTF16LE, 0, binCollFunc, 0);
2934   createCollation(db, "NOCASE", SQLITE_UTF8, 0, nocaseCollatingFunc, 0);
2935   createCollation(db, "RTRIM", SQLITE_UTF8, (void*)1, binCollFunc, 0);
2936   if( db->mallocFailed ){
2937     goto opendb_out;
2938   }
2939   /* EVIDENCE-OF: R-08308-17224 The default collating function for all
2940   ** strings is BINARY.
2941   */
2942   db->pDfltColl = sqlite3FindCollSeq(db, SQLITE_UTF8, sqlite3StrBINARY, 0);
2943   assert( db->pDfltColl!=0 );
2944 
2945   /* Parse the filename/URI argument. */
2946   db->openFlags = flags;
2947   rc = sqlite3ParseUri(zVfs, zFilename, &flags, &db->pVfs, &zOpen, &zErrMsg);
2948   if( rc!=SQLITE_OK ){
2949     if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
2950     sqlite3ErrorWithMsg(db, rc, zErrMsg ? "%s" : 0, zErrMsg);
2951     sqlite3_free(zErrMsg);
2952     goto opendb_out;
2953   }
2954 
2955   /* Open the backend database driver */
2956   rc = sqlite3BtreeOpen(db->pVfs, zOpen, db, &db->aDb[0].pBt, 0,
2957                         flags | SQLITE_OPEN_MAIN_DB);
2958   if( rc!=SQLITE_OK ){
2959     if( rc==SQLITE_IOERR_NOMEM ){
2960       rc = SQLITE_NOMEM_BKPT;
2961     }
2962     sqlite3Error(db, rc);
2963     goto opendb_out;
2964   }
2965   sqlite3BtreeEnter(db->aDb[0].pBt);
2966   db->aDb[0].pSchema = sqlite3SchemaGet(db, db->aDb[0].pBt);
2967   if( !db->mallocFailed ) ENC(db) = SCHEMA_ENC(db);
2968   sqlite3BtreeLeave(db->aDb[0].pBt);
2969   db->aDb[1].pSchema = sqlite3SchemaGet(db, 0);
2970 
2971   /* The default safety_level for the main database is FULL; for the temp
2972   ** database it is OFF. This matches the pager layer defaults.
2973   */
2974   db->aDb[0].zDbSName = "main";
2975   db->aDb[0].safety_level = SQLITE_DEFAULT_SYNCHRONOUS+1;
2976   db->aDb[1].zDbSName = "temp";
2977   db->aDb[1].safety_level = PAGER_SYNCHRONOUS_OFF;
2978 
2979   db->magic = SQLITE_MAGIC_OPEN;
2980   if( db->mallocFailed ){
2981     goto opendb_out;
2982   }
2983 
2984   /* Register all built-in functions, but do not attempt to read the
2985   ** database schema yet. This is delayed until the first time the database
2986   ** is accessed.
2987   */
2988   sqlite3Error(db, SQLITE_OK);
2989   sqlite3RegisterPerConnectionBuiltinFunctions(db);
2990   rc = sqlite3_errcode(db);
2991 
2992 #ifdef SQLITE_ENABLE_FTS5
2993   /* Register any built-in FTS5 module before loading the automatic
2994   ** extensions. This allows automatic extensions to register FTS5
2995   ** tokenizers and auxiliary functions.  */
2996   if( !db->mallocFailed && rc==SQLITE_OK ){
2997     rc = sqlite3Fts5Init(db);
2998   }
2999 #endif
3000 
3001   /* Load automatic extensions - extensions that have been registered
3002   ** using the sqlite3_automatic_extension() API.
3003   */
3004   if( rc==SQLITE_OK ){
3005     sqlite3AutoLoadExtensions(db);
3006     rc = sqlite3_errcode(db);
3007     if( rc!=SQLITE_OK ){
3008       goto opendb_out;
3009     }
3010   }
3011 
3012 #ifdef SQLITE_ENABLE_FTS1
3013   if( !db->mallocFailed ){
3014     extern int sqlite3Fts1Init(sqlite3*);
3015     rc = sqlite3Fts1Init(db);
3016   }
3017 #endif
3018 
3019 #ifdef SQLITE_ENABLE_FTS2
3020   if( !db->mallocFailed && rc==SQLITE_OK ){
3021     extern int sqlite3Fts2Init(sqlite3*);
3022     rc = sqlite3Fts2Init(db);
3023   }
3024 #endif
3025 
3026 #ifdef SQLITE_ENABLE_FTS3 /* automatically defined by SQLITE_ENABLE_FTS4 */
3027   if( !db->mallocFailed && rc==SQLITE_OK ){
3028     rc = sqlite3Fts3Init(db);
3029   }
3030 #endif
3031 
3032 #ifdef SQLITE_ENABLE_ICU
3033   if( !db->mallocFailed && rc==SQLITE_OK ){
3034     rc = sqlite3IcuInit(db);
3035   }
3036 #endif
3037 
3038 #ifdef SQLITE_ENABLE_RTREE
3039   if( !db->mallocFailed && rc==SQLITE_OK){
3040     rc = sqlite3RtreeInit(db);
3041   }
3042 #endif
3043 
3044 #ifdef SQLITE_ENABLE_DBSTAT_VTAB
3045   if( !db->mallocFailed && rc==SQLITE_OK){
3046     rc = sqlite3DbstatRegister(db);
3047   }
3048 #endif
3049 
3050 #ifdef SQLITE_ENABLE_JSON1
3051   if( !db->mallocFailed && rc==SQLITE_OK){
3052     rc = sqlite3Json1Init(db);
3053   }
3054 #endif
3055 
3056   /* -DSQLITE_DEFAULT_LOCKING_MODE=1 makes EXCLUSIVE the default locking
3057   ** mode.  -DSQLITE_DEFAULT_LOCKING_MODE=0 make NORMAL the default locking
3058   ** mode.  Doing nothing at all also makes NORMAL the default.
3059   */
3060 #ifdef SQLITE_DEFAULT_LOCKING_MODE
3061   db->dfltLockMode = SQLITE_DEFAULT_LOCKING_MODE;
3062   sqlite3PagerLockingMode(sqlite3BtreePager(db->aDb[0].pBt),
3063                           SQLITE_DEFAULT_LOCKING_MODE);
3064 #endif
3065 
3066   if( rc ) sqlite3Error(db, rc);
3067 
3068   /* Enable the lookaside-malloc subsystem */
3069   setupLookaside(db, 0, sqlite3GlobalConfig.szLookaside,
3070                         sqlite3GlobalConfig.nLookaside);
3071 
3072   sqlite3_wal_autocheckpoint(db, SQLITE_DEFAULT_WAL_AUTOCHECKPOINT);
3073 
3074 opendb_out:
3075   if( db ){
3076     assert( db->mutex!=0 || isThreadsafe==0
3077            || sqlite3GlobalConfig.bFullMutex==0 );
3078     sqlite3_mutex_leave(db->mutex);
3079   }
3080   rc = sqlite3_errcode(db);
3081   assert( db!=0 || rc==SQLITE_NOMEM );
3082   if( rc==SQLITE_NOMEM ){
3083     sqlite3_close(db);
3084     db = 0;
3085   }else if( rc!=SQLITE_OK ){
3086     db->magic = SQLITE_MAGIC_SICK;
3087   }
3088   *ppDb = db;
3089 #ifdef SQLITE_ENABLE_SQLLOG
3090   if( sqlite3GlobalConfig.xSqllog ){
3091     /* Opening a db handle. Fourth parameter is passed 0. */
3092     void *pArg = sqlite3GlobalConfig.pSqllogArg;
3093     sqlite3GlobalConfig.xSqllog(pArg, db, zFilename, 0);
3094   }
3095 #endif
3096 #if defined(SQLITE_HAS_CODEC)
3097   if( rc==SQLITE_OK ){
3098     const char *zHexKey = sqlite3_uri_parameter(zOpen, "hexkey");
3099     if( zHexKey && zHexKey[0] ){
3100       u8 iByte;
3101       int i;
3102       char zKey[40];
3103       for(i=0, iByte=0; i<sizeof(zKey)*2 && sqlite3Isxdigit(zHexKey[i]); i++){
3104         iByte = (iByte<<4) + sqlite3HexToInt(zHexKey[i]);
3105         if( (i&1)!=0 ) zKey[i/2] = iByte;
3106       }
3107       sqlite3_key_v2(db, 0, zKey, i/2);
3108     }
3109   }
3110 #endif
3111   sqlite3_free(zOpen);
3112   return rc & 0xff;
3113 }
3114 
3115 /*
3116 ** Open a new database handle.
3117 */
3118 int sqlite3_open(
3119   const char *zFilename,
3120   sqlite3 **ppDb
3121 ){
3122   return openDatabase(zFilename, ppDb,
3123                       SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0);
3124 }
3125 int sqlite3_open_v2(
3126   const char *filename,   /* Database filename (UTF-8) */
3127   sqlite3 **ppDb,         /* OUT: SQLite db handle */
3128   int flags,              /* Flags */
3129   const char *zVfs        /* Name of VFS module to use */
3130 ){
3131   return openDatabase(filename, ppDb, (unsigned int)flags, zVfs);
3132 }
3133 
3134 #ifndef SQLITE_OMIT_UTF16
3135 /*
3136 ** Open a new database handle.
3137 */
3138 int sqlite3_open16(
3139   const void *zFilename,
3140   sqlite3 **ppDb
3141 ){
3142   char const *zFilename8;   /* zFilename encoded in UTF-8 instead of UTF-16 */
3143   sqlite3_value *pVal;
3144   int rc;
3145 
3146 #ifdef SQLITE_ENABLE_API_ARMOR
3147   if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
3148 #endif
3149   *ppDb = 0;
3150 #ifndef SQLITE_OMIT_AUTOINIT
3151   rc = sqlite3_initialize();
3152   if( rc ) return rc;
3153 #endif
3154   if( zFilename==0 ) zFilename = "\000\000";
3155   pVal = sqlite3ValueNew(0);
3156   sqlite3ValueSetStr(pVal, -1, zFilename, SQLITE_UTF16NATIVE, SQLITE_STATIC);
3157   zFilename8 = sqlite3ValueText(pVal, SQLITE_UTF8);
3158   if( zFilename8 ){
3159     rc = openDatabase(zFilename8, ppDb,
3160                       SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0);
3161     assert( *ppDb || rc==SQLITE_NOMEM );
3162     if( rc==SQLITE_OK && !DbHasProperty(*ppDb, 0, DB_SchemaLoaded) ){
3163       SCHEMA_ENC(*ppDb) = ENC(*ppDb) = SQLITE_UTF16NATIVE;
3164     }
3165   }else{
3166     rc = SQLITE_NOMEM_BKPT;
3167   }
3168   sqlite3ValueFree(pVal);
3169 
3170   return rc & 0xff;
3171 }
3172 #endif /* SQLITE_OMIT_UTF16 */
3173 
3174 /*
3175 ** Register a new collation sequence with the database handle db.
3176 */
3177 int sqlite3_create_collation(
3178   sqlite3* db,
3179   const char *zName,
3180   int enc,
3181   void* pCtx,
3182   int(*xCompare)(void*,int,const void*,int,const void*)
3183 ){
3184   return sqlite3_create_collation_v2(db, zName, enc, pCtx, xCompare, 0);
3185 }
3186 
3187 /*
3188 ** Register a new collation sequence with the database handle db.
3189 */
3190 int sqlite3_create_collation_v2(
3191   sqlite3* db,
3192   const char *zName,
3193   int enc,
3194   void* pCtx,
3195   int(*xCompare)(void*,int,const void*,int,const void*),
3196   void(*xDel)(void*)
3197 ){
3198   int rc;
3199 
3200 #ifdef SQLITE_ENABLE_API_ARMOR
3201   if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
3202 #endif
3203   sqlite3_mutex_enter(db->mutex);
3204   assert( !db->mallocFailed );
3205   rc = createCollation(db, zName, (u8)enc, pCtx, xCompare, xDel);
3206   rc = sqlite3ApiExit(db, rc);
3207   sqlite3_mutex_leave(db->mutex);
3208   return rc;
3209 }
3210 
3211 #ifndef SQLITE_OMIT_UTF16
3212 /*
3213 ** Register a new collation sequence with the database handle db.
3214 */
3215 int sqlite3_create_collation16(
3216   sqlite3* db,
3217   const void *zName,
3218   int enc,
3219   void* pCtx,
3220   int(*xCompare)(void*,int,const void*,int,const void*)
3221 ){
3222   int rc = SQLITE_OK;
3223   char *zName8;
3224 
3225 #ifdef SQLITE_ENABLE_API_ARMOR
3226   if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
3227 #endif
3228   sqlite3_mutex_enter(db->mutex);
3229   assert( !db->mallocFailed );
3230   zName8 = sqlite3Utf16to8(db, zName, -1, SQLITE_UTF16NATIVE);
3231   if( zName8 ){
3232     rc = createCollation(db, zName8, (u8)enc, pCtx, xCompare, 0);
3233     sqlite3DbFree(db, zName8);
3234   }
3235   rc = sqlite3ApiExit(db, rc);
3236   sqlite3_mutex_leave(db->mutex);
3237   return rc;
3238 }
3239 #endif /* SQLITE_OMIT_UTF16 */
3240 
3241 /*
3242 ** Register a collation sequence factory callback with the database handle
3243 ** db. Replace any previously installed collation sequence factory.
3244 */
3245 int sqlite3_collation_needed(
3246   sqlite3 *db,
3247   void *pCollNeededArg,
3248   void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*)
3249 ){
3250 #ifdef SQLITE_ENABLE_API_ARMOR
3251   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3252 #endif
3253   sqlite3_mutex_enter(db->mutex);
3254   db->xCollNeeded = xCollNeeded;
3255   db->xCollNeeded16 = 0;
3256   db->pCollNeededArg = pCollNeededArg;
3257   sqlite3_mutex_leave(db->mutex);
3258   return SQLITE_OK;
3259 }
3260 
3261 #ifndef SQLITE_OMIT_UTF16
3262 /*
3263 ** Register a collation sequence factory callback with the database handle
3264 ** db. Replace any previously installed collation sequence factory.
3265 */
3266 int sqlite3_collation_needed16(
3267   sqlite3 *db,
3268   void *pCollNeededArg,
3269   void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*)
3270 ){
3271 #ifdef SQLITE_ENABLE_API_ARMOR
3272   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3273 #endif
3274   sqlite3_mutex_enter(db->mutex);
3275   db->xCollNeeded = 0;
3276   db->xCollNeeded16 = xCollNeeded16;
3277   db->pCollNeededArg = pCollNeededArg;
3278   sqlite3_mutex_leave(db->mutex);
3279   return SQLITE_OK;
3280 }
3281 #endif /* SQLITE_OMIT_UTF16 */
3282 
3283 #ifndef SQLITE_OMIT_DEPRECATED
3284 /*
3285 ** This function is now an anachronism. It used to be used to recover from a
3286 ** malloc() failure, but SQLite now does this automatically.
3287 */
3288 int sqlite3_global_recover(void){
3289   return SQLITE_OK;
3290 }
3291 #endif
3292 
3293 /*
3294 ** Test to see whether or not the database connection is in autocommit
3295 ** mode.  Return TRUE if it is and FALSE if not.  Autocommit mode is on
3296 ** by default.  Autocommit is disabled by a BEGIN statement and reenabled
3297 ** by the next COMMIT or ROLLBACK.
3298 */
3299 int sqlite3_get_autocommit(sqlite3 *db){
3300 #ifdef SQLITE_ENABLE_API_ARMOR
3301   if( !sqlite3SafetyCheckOk(db) ){
3302     (void)SQLITE_MISUSE_BKPT;
3303     return 0;
3304   }
3305 #endif
3306   return db->autoCommit;
3307 }
3308 
3309 /*
3310 ** The following routines are substitutes for constants SQLITE_CORRUPT,
3311 ** SQLITE_MISUSE, SQLITE_CANTOPEN, SQLITE_NOMEM and possibly other error
3312 ** constants.  They serve two purposes:
3313 **
3314 **   1.  Serve as a convenient place to set a breakpoint in a debugger
3315 **       to detect when version error conditions occurs.
3316 **
3317 **   2.  Invoke sqlite3_log() to provide the source code location where
3318 **       a low-level error is first detected.
3319 */
3320 static int reportError(int iErr, int lineno, const char *zType){
3321   sqlite3_log(iErr, "%s at line %d of [%.10s]",
3322               zType, lineno, 20+sqlite3_sourceid());
3323   return iErr;
3324 }
3325 int sqlite3CorruptError(int lineno){
3326   testcase( sqlite3GlobalConfig.xLog!=0 );
3327   return reportError(SQLITE_CORRUPT, lineno, "database corruption");
3328 }
3329 int sqlite3MisuseError(int lineno){
3330   testcase( sqlite3GlobalConfig.xLog!=0 );
3331   return reportError(SQLITE_MISUSE, lineno, "misuse");
3332 }
3333 int sqlite3CantopenError(int lineno){
3334   testcase( sqlite3GlobalConfig.xLog!=0 );
3335   return reportError(SQLITE_CANTOPEN, lineno, "cannot open file");
3336 }
3337 #ifdef SQLITE_DEBUG
3338 int sqlite3NomemError(int lineno){
3339   testcase( sqlite3GlobalConfig.xLog!=0 );
3340   return reportError(SQLITE_NOMEM, lineno, "OOM");
3341 }
3342 int sqlite3IoerrnomemError(int lineno){
3343   testcase( sqlite3GlobalConfig.xLog!=0 );
3344   return reportError(SQLITE_IOERR_NOMEM, lineno, "I/O OOM error");
3345 }
3346 #endif
3347 
3348 #ifndef SQLITE_OMIT_DEPRECATED
3349 /*
3350 ** This is a convenience routine that makes sure that all thread-specific
3351 ** data for this thread has been deallocated.
3352 **
3353 ** SQLite no longer uses thread-specific data so this routine is now a
3354 ** no-op.  It is retained for historical compatibility.
3355 */
3356 void sqlite3_thread_cleanup(void){
3357 }
3358 #endif
3359 
3360 /*
3361 ** Return meta information about a specific column of a database table.
3362 ** See comment in sqlite3.h (sqlite.h.in) for details.
3363 */
3364 int sqlite3_table_column_metadata(
3365   sqlite3 *db,                /* Connection handle */
3366   const char *zDbName,        /* Database name or NULL */
3367   const char *zTableName,     /* Table name */
3368   const char *zColumnName,    /* Column name */
3369   char const **pzDataType,    /* OUTPUT: Declared data type */
3370   char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
3371   int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
3372   int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
3373   int *pAutoinc               /* OUTPUT: True if column is auto-increment */
3374 ){
3375   int rc;
3376   char *zErrMsg = 0;
3377   Table *pTab = 0;
3378   Column *pCol = 0;
3379   int iCol = 0;
3380   char const *zDataType = 0;
3381   char const *zCollSeq = 0;
3382   int notnull = 0;
3383   int primarykey = 0;
3384   int autoinc = 0;
3385 
3386 
3387 #ifdef SQLITE_ENABLE_API_ARMOR
3388   if( !sqlite3SafetyCheckOk(db) || zTableName==0 ){
3389     return SQLITE_MISUSE_BKPT;
3390   }
3391 #endif
3392 
3393   /* Ensure the database schema has been loaded */
3394   sqlite3_mutex_enter(db->mutex);
3395   sqlite3BtreeEnterAll(db);
3396   rc = sqlite3Init(db, &zErrMsg);
3397   if( SQLITE_OK!=rc ){
3398     goto error_out;
3399   }
3400 
3401   /* Locate the table in question */
3402   pTab = sqlite3FindTable(db, zTableName, zDbName);
3403   if( !pTab || pTab->pSelect ){
3404     pTab = 0;
3405     goto error_out;
3406   }
3407 
3408   /* Find the column for which info is requested */
3409   if( zColumnName==0 ){
3410     /* Query for existance of table only */
3411   }else{
3412     for(iCol=0; iCol<pTab->nCol; iCol++){
3413       pCol = &pTab->aCol[iCol];
3414       if( 0==sqlite3StrICmp(pCol->zName, zColumnName) ){
3415         break;
3416       }
3417     }
3418     if( iCol==pTab->nCol ){
3419       if( HasRowid(pTab) && sqlite3IsRowid(zColumnName) ){
3420         iCol = pTab->iPKey;
3421         pCol = iCol>=0 ? &pTab->aCol[iCol] : 0;
3422       }else{
3423         pTab = 0;
3424         goto error_out;
3425       }
3426     }
3427   }
3428 
3429   /* The following block stores the meta information that will be returned
3430   ** to the caller in local variables zDataType, zCollSeq, notnull, primarykey
3431   ** and autoinc. At this point there are two possibilities:
3432   **
3433   **     1. The specified column name was rowid", "oid" or "_rowid_"
3434   **        and there is no explicitly declared IPK column.
3435   **
3436   **     2. The table is not a view and the column name identified an
3437   **        explicitly declared column. Copy meta information from *pCol.
3438   */
3439   if( pCol ){
3440     zDataType = sqlite3ColumnType(pCol,0);
3441     zCollSeq = pCol->zColl;
3442     notnull = pCol->notNull!=0;
3443     primarykey  = (pCol->colFlags & COLFLAG_PRIMKEY)!=0;
3444     autoinc = pTab->iPKey==iCol && (pTab->tabFlags & TF_Autoincrement)!=0;
3445   }else{
3446     zDataType = "INTEGER";
3447     primarykey = 1;
3448   }
3449   if( !zCollSeq ){
3450     zCollSeq = sqlite3StrBINARY;
3451   }
3452 
3453 error_out:
3454   sqlite3BtreeLeaveAll(db);
3455 
3456   /* Whether the function call succeeded or failed, set the output parameters
3457   ** to whatever their local counterparts contain. If an error did occur,
3458   ** this has the effect of zeroing all output parameters.
3459   */
3460   if( pzDataType ) *pzDataType = zDataType;
3461   if( pzCollSeq ) *pzCollSeq = zCollSeq;
3462   if( pNotNull ) *pNotNull = notnull;
3463   if( pPrimaryKey ) *pPrimaryKey = primarykey;
3464   if( pAutoinc ) *pAutoinc = autoinc;
3465 
3466   if( SQLITE_OK==rc && !pTab ){
3467     sqlite3DbFree(db, zErrMsg);
3468     zErrMsg = sqlite3MPrintf(db, "no such table column: %s.%s", zTableName,
3469         zColumnName);
3470     rc = SQLITE_ERROR;
3471   }
3472   sqlite3ErrorWithMsg(db, rc, (zErrMsg?"%s":0), zErrMsg);
3473   sqlite3DbFree(db, zErrMsg);
3474   rc = sqlite3ApiExit(db, rc);
3475   sqlite3_mutex_leave(db->mutex);
3476   return rc;
3477 }
3478 
3479 /*
3480 ** Sleep for a little while.  Return the amount of time slept.
3481 */
3482 int sqlite3_sleep(int ms){
3483   sqlite3_vfs *pVfs;
3484   int rc;
3485   pVfs = sqlite3_vfs_find(0);
3486   if( pVfs==0 ) return 0;
3487 
3488   /* This function works in milliseconds, but the underlying OsSleep()
3489   ** API uses microseconds. Hence the 1000's.
3490   */
3491   rc = (sqlite3OsSleep(pVfs, 1000*ms)/1000);
3492   return rc;
3493 }
3494 
3495 /*
3496 ** Enable or disable the extended result codes.
3497 */
3498 int sqlite3_extended_result_codes(sqlite3 *db, int onoff){
3499 #ifdef SQLITE_ENABLE_API_ARMOR
3500   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3501 #endif
3502   sqlite3_mutex_enter(db->mutex);
3503   db->errMask = onoff ? 0xffffffff : 0xff;
3504   sqlite3_mutex_leave(db->mutex);
3505   return SQLITE_OK;
3506 }
3507 
3508 /*
3509 ** Invoke the xFileControl method on a particular database.
3510 */
3511 int sqlite3_file_control(sqlite3 *db, const char *zDbName, int op, void *pArg){
3512   int rc = SQLITE_ERROR;
3513   Btree *pBtree;
3514 
3515 #ifdef SQLITE_ENABLE_API_ARMOR
3516   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
3517 #endif
3518   sqlite3_mutex_enter(db->mutex);
3519   pBtree = sqlite3DbNameToBtree(db, zDbName);
3520   if( pBtree ){
3521     Pager *pPager;
3522     sqlite3_file *fd;
3523     sqlite3BtreeEnter(pBtree);
3524     pPager = sqlite3BtreePager(pBtree);
3525     assert( pPager!=0 );
3526     fd = sqlite3PagerFile(pPager);
3527     assert( fd!=0 );
3528     if( op==SQLITE_FCNTL_FILE_POINTER ){
3529       *(sqlite3_file**)pArg = fd;
3530       rc = SQLITE_OK;
3531     }else if( op==SQLITE_FCNTL_VFS_POINTER ){
3532       *(sqlite3_vfs**)pArg = sqlite3PagerVfs(pPager);
3533       rc = SQLITE_OK;
3534     }else if( op==SQLITE_FCNTL_JOURNAL_POINTER ){
3535       *(sqlite3_file**)pArg = sqlite3PagerJrnlFile(pPager);
3536       rc = SQLITE_OK;
3537     }else if( fd->pMethods ){
3538       rc = sqlite3OsFileControl(fd, op, pArg);
3539     }else{
3540       rc = SQLITE_NOTFOUND;
3541     }
3542     sqlite3BtreeLeave(pBtree);
3543   }
3544   sqlite3_mutex_leave(db->mutex);
3545   return rc;
3546 }
3547 
3548 /*
3549 ** Interface to the testing logic.
3550 */
3551 int sqlite3_test_control(int op, ...){
3552   int rc = 0;
3553 #ifdef SQLITE_UNTESTABLE
3554   UNUSED_PARAMETER(op);
3555 #else
3556   va_list ap;
3557   va_start(ap, op);
3558   switch( op ){
3559 
3560     /*
3561     ** Save the current state of the PRNG.
3562     */
3563     case SQLITE_TESTCTRL_PRNG_SAVE: {
3564       sqlite3PrngSaveState();
3565       break;
3566     }
3567 
3568     /*
3569     ** Restore the state of the PRNG to the last state saved using
3570     ** PRNG_SAVE.  If PRNG_SAVE has never before been called, then
3571     ** this verb acts like PRNG_RESET.
3572     */
3573     case SQLITE_TESTCTRL_PRNG_RESTORE: {
3574       sqlite3PrngRestoreState();
3575       break;
3576     }
3577 
3578     /*
3579     ** Reset the PRNG back to its uninitialized state.  The next call
3580     ** to sqlite3_randomness() will reseed the PRNG using a single call
3581     ** to the xRandomness method of the default VFS.
3582     */
3583     case SQLITE_TESTCTRL_PRNG_RESET: {
3584       sqlite3_randomness(0,0);
3585       break;
3586     }
3587 
3588     /*
3589     **  sqlite3_test_control(BITVEC_TEST, size, program)
3590     **
3591     ** Run a test against a Bitvec object of size.  The program argument
3592     ** is an array of integers that defines the test.  Return -1 on a
3593     ** memory allocation error, 0 on success, or non-zero for an error.
3594     ** See the sqlite3BitvecBuiltinTest() for additional information.
3595     */
3596     case SQLITE_TESTCTRL_BITVEC_TEST: {
3597       int sz = va_arg(ap, int);
3598       int *aProg = va_arg(ap, int*);
3599       rc = sqlite3BitvecBuiltinTest(sz, aProg);
3600       break;
3601     }
3602 
3603     /*
3604     **  sqlite3_test_control(FAULT_INSTALL, xCallback)
3605     **
3606     ** Arrange to invoke xCallback() whenever sqlite3FaultSim() is called,
3607     ** if xCallback is not NULL.
3608     **
3609     ** As a test of the fault simulator mechanism itself, sqlite3FaultSim(0)
3610     ** is called immediately after installing the new callback and the return
3611     ** value from sqlite3FaultSim(0) becomes the return from
3612     ** sqlite3_test_control().
3613     */
3614     case SQLITE_TESTCTRL_FAULT_INSTALL: {
3615       /* MSVC is picky about pulling func ptrs from va lists.
3616       ** http://support.microsoft.com/kb/47961
3617       ** sqlite3GlobalConfig.xTestCallback = va_arg(ap, int(*)(int));
3618       */
3619       typedef int(*TESTCALLBACKFUNC_t)(int);
3620       sqlite3GlobalConfig.xTestCallback = va_arg(ap, TESTCALLBACKFUNC_t);
3621       rc = sqlite3FaultSim(0);
3622       break;
3623     }
3624 
3625     /*
3626     **  sqlite3_test_control(BENIGN_MALLOC_HOOKS, xBegin, xEnd)
3627     **
3628     ** Register hooks to call to indicate which malloc() failures
3629     ** are benign.
3630     */
3631     case SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS: {
3632       typedef void (*void_function)(void);
3633       void_function xBenignBegin;
3634       void_function xBenignEnd;
3635       xBenignBegin = va_arg(ap, void_function);
3636       xBenignEnd = va_arg(ap, void_function);
3637       sqlite3BenignMallocHooks(xBenignBegin, xBenignEnd);
3638       break;
3639     }
3640 
3641     /*
3642     **  sqlite3_test_control(SQLITE_TESTCTRL_PENDING_BYTE, unsigned int X)
3643     **
3644     ** Set the PENDING byte to the value in the argument, if X>0.
3645     ** Make no changes if X==0.  Return the value of the pending byte
3646     ** as it existing before this routine was called.
3647     **
3648     ** IMPORTANT:  Changing the PENDING byte from 0x40000000 results in
3649     ** an incompatible database file format.  Changing the PENDING byte
3650     ** while any database connection is open results in undefined and
3651     ** deleterious behavior.
3652     */
3653     case SQLITE_TESTCTRL_PENDING_BYTE: {
3654       rc = PENDING_BYTE;
3655 #ifndef SQLITE_OMIT_WSD
3656       {
3657         unsigned int newVal = va_arg(ap, unsigned int);
3658         if( newVal ) sqlite3PendingByte = newVal;
3659       }
3660 #endif
3661       break;
3662     }
3663 
3664     /*
3665     **  sqlite3_test_control(SQLITE_TESTCTRL_ASSERT, int X)
3666     **
3667     ** This action provides a run-time test to see whether or not
3668     ** assert() was enabled at compile-time.  If X is true and assert()
3669     ** is enabled, then the return value is true.  If X is true and
3670     ** assert() is disabled, then the return value is zero.  If X is
3671     ** false and assert() is enabled, then the assertion fires and the
3672     ** process aborts.  If X is false and assert() is disabled, then the
3673     ** return value is zero.
3674     */
3675     case SQLITE_TESTCTRL_ASSERT: {
3676       volatile int x = 0;
3677       assert( /*side-effects-ok*/ (x = va_arg(ap,int))!=0 );
3678       rc = x;
3679       break;
3680     }
3681 
3682 
3683     /*
3684     **  sqlite3_test_control(SQLITE_TESTCTRL_ALWAYS, int X)
3685     **
3686     ** This action provides a run-time test to see how the ALWAYS and
3687     ** NEVER macros were defined at compile-time.
3688     **
3689     ** The return value is ALWAYS(X).
3690     **
3691     ** The recommended test is X==2.  If the return value is 2, that means
3692     ** ALWAYS() and NEVER() are both no-op pass-through macros, which is the
3693     ** default setting.  If the return value is 1, then ALWAYS() is either
3694     ** hard-coded to true or else it asserts if its argument is false.
3695     ** The first behavior (hard-coded to true) is the case if
3696     ** SQLITE_TESTCTRL_ASSERT shows that assert() is disabled and the second
3697     ** behavior (assert if the argument to ALWAYS() is false) is the case if
3698     ** SQLITE_TESTCTRL_ASSERT shows that assert() is enabled.
3699     **
3700     ** The run-time test procedure might look something like this:
3701     **
3702     **    if( sqlite3_test_control(SQLITE_TESTCTRL_ALWAYS, 2)==2 ){
3703     **      // ALWAYS() and NEVER() are no-op pass-through macros
3704     **    }else if( sqlite3_test_control(SQLITE_TESTCTRL_ASSERT, 1) ){
3705     **      // ALWAYS(x) asserts that x is true. NEVER(x) asserts x is false.
3706     **    }else{
3707     **      // ALWAYS(x) is a constant 1.  NEVER(x) is a constant 0.
3708     **    }
3709     */
3710     case SQLITE_TESTCTRL_ALWAYS: {
3711       int x = va_arg(ap,int);
3712       rc = ALWAYS(x);
3713       break;
3714     }
3715 
3716     /*
3717     **   sqlite3_test_control(SQLITE_TESTCTRL_BYTEORDER);
3718     **
3719     ** The integer returned reveals the byte-order of the computer on which
3720     ** SQLite is running:
3721     **
3722     **       1     big-endian,    determined at run-time
3723     **      10     little-endian, determined at run-time
3724     **  432101     big-endian,    determined at compile-time
3725     **  123410     little-endian, determined at compile-time
3726     */
3727     case SQLITE_TESTCTRL_BYTEORDER: {
3728       rc = SQLITE_BYTEORDER*100 + SQLITE_LITTLEENDIAN*10 + SQLITE_BIGENDIAN;
3729       break;
3730     }
3731 
3732     /*   sqlite3_test_control(SQLITE_TESTCTRL_RESERVE, sqlite3 *db, int N)
3733     **
3734     ** Set the nReserve size to N for the main database on the database
3735     ** connection db.
3736     */
3737     case SQLITE_TESTCTRL_RESERVE: {
3738       sqlite3 *db = va_arg(ap, sqlite3*);
3739       int x = va_arg(ap,int);
3740       sqlite3_mutex_enter(db->mutex);
3741       sqlite3BtreeSetPageSize(db->aDb[0].pBt, 0, x, 0);
3742       sqlite3_mutex_leave(db->mutex);
3743       break;
3744     }
3745 
3746     /*  sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS, sqlite3 *db, int N)
3747     **
3748     ** Enable or disable various optimizations for testing purposes.  The
3749     ** argument N is a bitmask of optimizations to be disabled.  For normal
3750     ** operation N should be 0.  The idea is that a test program (like the
3751     ** SQL Logic Test or SLT test module) can run the same SQL multiple times
3752     ** with various optimizations disabled to verify that the same answer
3753     ** is obtained in every case.
3754     */
3755     case SQLITE_TESTCTRL_OPTIMIZATIONS: {
3756       sqlite3 *db = va_arg(ap, sqlite3*);
3757       db->dbOptFlags = (u16)(va_arg(ap, int) & 0xffff);
3758       break;
3759     }
3760 
3761 #ifdef SQLITE_N_KEYWORD
3762     /* sqlite3_test_control(SQLITE_TESTCTRL_ISKEYWORD, const char *zWord)
3763     **
3764     ** If zWord is a keyword recognized by the parser, then return the
3765     ** number of keywords.  Or if zWord is not a keyword, return 0.
3766     **
3767     ** This test feature is only available in the amalgamation since
3768     ** the SQLITE_N_KEYWORD macro is not defined in this file if SQLite
3769     ** is built using separate source files.
3770     */
3771     case SQLITE_TESTCTRL_ISKEYWORD: {
3772       const char *zWord = va_arg(ap, const char*);
3773       int n = sqlite3Strlen30(zWord);
3774       rc = (sqlite3KeywordCode((u8*)zWord, n)!=TK_ID) ? SQLITE_N_KEYWORD : 0;
3775       break;
3776     }
3777 #endif
3778 
3779     /* sqlite3_test_control(SQLITE_TESTCTRL_SCRATCHMALLOC, sz, &pNew, pFree);
3780     **
3781     ** Pass pFree into sqlite3ScratchFree().
3782     ** If sz>0 then allocate a scratch buffer into pNew.
3783     */
3784     case SQLITE_TESTCTRL_SCRATCHMALLOC: {
3785       void *pFree, **ppNew;
3786       int sz;
3787       sz = va_arg(ap, int);
3788       ppNew = va_arg(ap, void**);
3789       pFree = va_arg(ap, void*);
3790       if( sz ) *ppNew = sqlite3ScratchMalloc(sz);
3791       sqlite3ScratchFree(pFree);
3792       break;
3793     }
3794 
3795     /*   sqlite3_test_control(SQLITE_TESTCTRL_LOCALTIME_FAULT, int onoff);
3796     **
3797     ** If parameter onoff is non-zero, configure the wrappers so that all
3798     ** subsequent calls to localtime() and variants fail. If onoff is zero,
3799     ** undo this setting.
3800     */
3801     case SQLITE_TESTCTRL_LOCALTIME_FAULT: {
3802       sqlite3GlobalConfig.bLocaltimeFault = va_arg(ap, int);
3803       break;
3804     }
3805 
3806     /*   sqlite3_test_control(SQLITE_TESTCTRL_NEVER_CORRUPT, int);
3807     **
3808     ** Set or clear a flag that indicates that the database file is always well-
3809     ** formed and never corrupt.  This flag is clear by default, indicating that
3810     ** database files might have arbitrary corruption.  Setting the flag during
3811     ** testing causes certain assert() statements in the code to be activated
3812     ** that demonstrat invariants on well-formed database files.
3813     */
3814     case SQLITE_TESTCTRL_NEVER_CORRUPT: {
3815       sqlite3GlobalConfig.neverCorrupt = va_arg(ap, int);
3816       break;
3817     }
3818 
3819     /* Set the threshold at which OP_Once counters reset back to zero.
3820     ** By default this is 0x7ffffffe (over 2 billion), but that value is
3821     ** too big to test in a reasonable amount of time, so this control is
3822     ** provided to set a small and easily reachable reset value.
3823     */
3824     case SQLITE_TESTCTRL_ONCE_RESET_THRESHOLD: {
3825       sqlite3GlobalConfig.iOnceResetThreshold = va_arg(ap, int);
3826       break;
3827     }
3828 
3829     /*   sqlite3_test_control(SQLITE_TESTCTRL_VDBE_COVERAGE, xCallback, ptr);
3830     **
3831     ** Set the VDBE coverage callback function to xCallback with context
3832     ** pointer ptr.
3833     */
3834     case SQLITE_TESTCTRL_VDBE_COVERAGE: {
3835 #ifdef SQLITE_VDBE_COVERAGE
3836       typedef void (*branch_callback)(void*,int,u8,u8);
3837       sqlite3GlobalConfig.xVdbeBranch = va_arg(ap,branch_callback);
3838       sqlite3GlobalConfig.pVdbeBranchArg = va_arg(ap,void*);
3839 #endif
3840       break;
3841     }
3842 
3843     /*   sqlite3_test_control(SQLITE_TESTCTRL_SORTER_MMAP, db, nMax); */
3844     case SQLITE_TESTCTRL_SORTER_MMAP: {
3845       sqlite3 *db = va_arg(ap, sqlite3*);
3846       db->nMaxSorterMmap = va_arg(ap, int);
3847       break;
3848     }
3849 
3850     /*   sqlite3_test_control(SQLITE_TESTCTRL_ISINIT);
3851     **
3852     ** Return SQLITE_OK if SQLite has been initialized and SQLITE_ERROR if
3853     ** not.
3854     */
3855     case SQLITE_TESTCTRL_ISINIT: {
3856       if( sqlite3GlobalConfig.isInit==0 ) rc = SQLITE_ERROR;
3857       break;
3858     }
3859 
3860     /*  sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, db, dbName, onOff, tnum);
3861     **
3862     ** This test control is used to create imposter tables.  "db" is a pointer
3863     ** to the database connection.  dbName is the database name (ex: "main" or
3864     ** "temp") which will receive the imposter.  "onOff" turns imposter mode on
3865     ** or off.  "tnum" is the root page of the b-tree to which the imposter
3866     ** table should connect.
3867     **
3868     ** Enable imposter mode only when the schema has already been parsed.  Then
3869     ** run a single CREATE TABLE statement to construct the imposter table in
3870     ** the parsed schema.  Then turn imposter mode back off again.
3871     **
3872     ** If onOff==0 and tnum>0 then reset the schema for all databases, causing
3873     ** the schema to be reparsed the next time it is needed.  This has the
3874     ** effect of erasing all imposter tables.
3875     */
3876     case SQLITE_TESTCTRL_IMPOSTER: {
3877       sqlite3 *db = va_arg(ap, sqlite3*);
3878       sqlite3_mutex_enter(db->mutex);
3879       db->init.iDb = sqlite3FindDbName(db, va_arg(ap,const char*));
3880       db->init.busy = db->init.imposterTable = va_arg(ap,int);
3881       db->init.newTnum = va_arg(ap,int);
3882       if( db->init.busy==0 && db->init.newTnum>0 ){
3883         sqlite3ResetAllSchemasOfConnection(db);
3884       }
3885       sqlite3_mutex_leave(db->mutex);
3886       break;
3887     }
3888   }
3889   va_end(ap);
3890 #endif /* SQLITE_UNTESTABLE */
3891   return rc;
3892 }
3893 
3894 /*
3895 ** This is a utility routine, useful to VFS implementations, that checks
3896 ** to see if a database file was a URI that contained a specific query
3897 ** parameter, and if so obtains the value of the query parameter.
3898 **
3899 ** The zFilename argument is the filename pointer passed into the xOpen()
3900 ** method of a VFS implementation.  The zParam argument is the name of the
3901 ** query parameter we seek.  This routine returns the value of the zParam
3902 ** parameter if it exists.  If the parameter does not exist, this routine
3903 ** returns a NULL pointer.
3904 */
3905 const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam){
3906   if( zFilename==0 || zParam==0 ) return 0;
3907   zFilename += sqlite3Strlen30(zFilename) + 1;
3908   while( zFilename[0] ){
3909     int x = strcmp(zFilename, zParam);
3910     zFilename += sqlite3Strlen30(zFilename) + 1;
3911     if( x==0 ) return zFilename;
3912     zFilename += sqlite3Strlen30(zFilename) + 1;
3913   }
3914   return 0;
3915 }
3916 
3917 /*
3918 ** Return a boolean value for a query parameter.
3919 */
3920 int sqlite3_uri_boolean(const char *zFilename, const char *zParam, int bDflt){
3921   const char *z = sqlite3_uri_parameter(zFilename, zParam);
3922   bDflt = bDflt!=0;
3923   return z ? sqlite3GetBoolean(z, bDflt) : bDflt;
3924 }
3925 
3926 /*
3927 ** Return a 64-bit integer value for a query parameter.
3928 */
3929 sqlite3_int64 sqlite3_uri_int64(
3930   const char *zFilename,    /* Filename as passed to xOpen */
3931   const char *zParam,       /* URI parameter sought */
3932   sqlite3_int64 bDflt       /* return if parameter is missing */
3933 ){
3934   const char *z = sqlite3_uri_parameter(zFilename, zParam);
3935   sqlite3_int64 v;
3936   if( z && sqlite3DecOrHexToI64(z, &v)==SQLITE_OK ){
3937     bDflt = v;
3938   }
3939   return bDflt;
3940 }
3941 
3942 /*
3943 ** Return the Btree pointer identified by zDbName.  Return NULL if not found.
3944 */
3945 Btree *sqlite3DbNameToBtree(sqlite3 *db, const char *zDbName){
3946   int iDb = zDbName ? sqlite3FindDbName(db, zDbName) : 0;
3947   return iDb<0 ? 0 : db->aDb[iDb].pBt;
3948 }
3949 
3950 /*
3951 ** Return the filename of the database associated with a database
3952 ** connection.
3953 */
3954 const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName){
3955   Btree *pBt;
3956 #ifdef SQLITE_ENABLE_API_ARMOR
3957   if( !sqlite3SafetyCheckOk(db) ){
3958     (void)SQLITE_MISUSE_BKPT;
3959     return 0;
3960   }
3961 #endif
3962   pBt = sqlite3DbNameToBtree(db, zDbName);
3963   return pBt ? sqlite3BtreeGetFilename(pBt) : 0;
3964 }
3965 
3966 /*
3967 ** Return 1 if database is read-only or 0 if read/write.  Return -1 if
3968 ** no such database exists.
3969 */
3970 int sqlite3_db_readonly(sqlite3 *db, const char *zDbName){
3971   Btree *pBt;
3972 #ifdef SQLITE_ENABLE_API_ARMOR
3973   if( !sqlite3SafetyCheckOk(db) ){
3974     (void)SQLITE_MISUSE_BKPT;
3975     return -1;
3976   }
3977 #endif
3978   pBt = sqlite3DbNameToBtree(db, zDbName);
3979   return pBt ? sqlite3BtreeIsReadonly(pBt) : -1;
3980 }
3981 
3982 #ifdef SQLITE_ENABLE_SNAPSHOT
3983 /*
3984 ** Obtain a snapshot handle for the snapshot of database zDb currently
3985 ** being read by handle db.
3986 */
3987 int sqlite3_snapshot_get(
3988   sqlite3 *db,
3989   const char *zDb,
3990   sqlite3_snapshot **ppSnapshot
3991 ){
3992   int rc = SQLITE_ERROR;
3993 #ifndef SQLITE_OMIT_WAL
3994 
3995 #ifdef SQLITE_ENABLE_API_ARMOR
3996   if( !sqlite3SafetyCheckOk(db) ){
3997     return SQLITE_MISUSE_BKPT;
3998   }
3999 #endif
4000   sqlite3_mutex_enter(db->mutex);
4001 
4002   if( db->autoCommit==0 ){
4003     int iDb = sqlite3FindDbName(db, zDb);
4004     if( iDb==0 || iDb>1 ){
4005       Btree *pBt = db->aDb[iDb].pBt;
4006       if( 0==sqlite3BtreeIsInTrans(pBt) ){
4007         rc = sqlite3BtreeBeginTrans(pBt, 0);
4008         if( rc==SQLITE_OK ){
4009           rc = sqlite3PagerSnapshotGet(sqlite3BtreePager(pBt), ppSnapshot);
4010         }
4011       }
4012     }
4013   }
4014 
4015   sqlite3_mutex_leave(db->mutex);
4016 #endif   /* SQLITE_OMIT_WAL */
4017   return rc;
4018 }
4019 
4020 /*
4021 ** Open a read-transaction on the snapshot idendified by pSnapshot.
4022 */
4023 int sqlite3_snapshot_open(
4024   sqlite3 *db,
4025   const char *zDb,
4026   sqlite3_snapshot *pSnapshot
4027 ){
4028   int rc = SQLITE_ERROR;
4029 #ifndef SQLITE_OMIT_WAL
4030 
4031 #ifdef SQLITE_ENABLE_API_ARMOR
4032   if( !sqlite3SafetyCheckOk(db) ){
4033     return SQLITE_MISUSE_BKPT;
4034   }
4035 #endif
4036   sqlite3_mutex_enter(db->mutex);
4037   if( db->autoCommit==0 ){
4038     int iDb;
4039     iDb = sqlite3FindDbName(db, zDb);
4040     if( iDb==0 || iDb>1 ){
4041       Btree *pBt = db->aDb[iDb].pBt;
4042       if( 0==sqlite3BtreeIsInReadTrans(pBt) ){
4043         rc = sqlite3PagerSnapshotOpen(sqlite3BtreePager(pBt), pSnapshot);
4044         if( rc==SQLITE_OK ){
4045           rc = sqlite3BtreeBeginTrans(pBt, 0);
4046           sqlite3PagerSnapshotOpen(sqlite3BtreePager(pBt), 0);
4047         }
4048       }
4049     }
4050   }
4051 
4052   sqlite3_mutex_leave(db->mutex);
4053 #endif   /* SQLITE_OMIT_WAL */
4054   return rc;
4055 }
4056 
4057 /*
4058 ** Recover as many snapshots as possible from the wal file associated with
4059 ** schema zDb of database db.
4060 */
4061 int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb){
4062   int rc = SQLITE_ERROR;
4063   int iDb;
4064 #ifndef SQLITE_OMIT_WAL
4065 
4066 #ifdef SQLITE_ENABLE_API_ARMOR
4067   if( !sqlite3SafetyCheckOk(db) ){
4068     return SQLITE_MISUSE_BKPT;
4069   }
4070 #endif
4071 
4072   sqlite3_mutex_enter(db->mutex);
4073   iDb = sqlite3FindDbName(db, zDb);
4074   if( iDb==0 || iDb>1 ){
4075     Btree *pBt = db->aDb[iDb].pBt;
4076     if( 0==sqlite3BtreeIsInReadTrans(pBt) ){
4077       rc = sqlite3BtreeBeginTrans(pBt, 0);
4078       if( rc==SQLITE_OK ){
4079         rc = sqlite3PagerSnapshotRecover(sqlite3BtreePager(pBt));
4080         sqlite3BtreeCommit(pBt);
4081       }
4082     }
4083   }
4084   sqlite3_mutex_leave(db->mutex);
4085 #endif   /* SQLITE_OMIT_WAL */
4086   return rc;
4087 }
4088 
4089 /*
4090 ** Free a snapshot handle obtained from sqlite3_snapshot_get().
4091 */
4092 void sqlite3_snapshot_free(sqlite3_snapshot *pSnapshot){
4093   sqlite3_free(pSnapshot);
4094 }
4095 #endif /* SQLITE_ENABLE_SNAPSHOT */
4096