xref: /sqlite-3.40.0/src/loadext.c (revision b43be55e) 
1 /*
2 ** 2006 June 7
3 **
4 ** The author disclaims copyright to this source code.  In place of
5 ** a legal notice, here is a blessing:
6 **
7 **    May you do good and not evil.
8 **    May you find forgiveness for yourself and forgive others.
9 **    May you share freely, never taking more than you give.
10 **
11 *************************************************************************
12 ** This file contains code used to dynamically load extensions into
13 ** the SQLite library.
14 */
15 
16 #ifndef SQLITE_CORE
17   #define SQLITE_CORE 1  /* Disable the API redefinition in sqlite3ext.h */
18 #endif
19 #include "sqlite3ext.h"
20 #include "sqliteInt.h"
21 #include <string.h>
22 
23 #ifndef SQLITE_OMIT_LOAD_EXTENSION
24 
25 /*
26 ** Some API routines are omitted when various features are
27 ** excluded from a build of SQLite.  Substitute a NULL pointer
28 ** for any missing APIs.
29 */
30 #ifndef SQLITE_ENABLE_COLUMN_METADATA
31 # define sqlite3_column_database_name   0
32 # define sqlite3_column_database_name16 0
33 # define sqlite3_column_table_name      0
34 # define sqlite3_column_table_name16    0
35 # define sqlite3_column_origin_name     0
36 # define sqlite3_column_origin_name16   0
37 #endif
38 
39 #ifdef SQLITE_OMIT_AUTHORIZATION
40 # define sqlite3_set_authorizer         0
41 #endif
42 
43 #ifdef SQLITE_OMIT_UTF16
44 # define sqlite3_bind_text16            0
45 # define sqlite3_collation_needed16     0
46 # define sqlite3_column_decltype16      0
47 # define sqlite3_column_name16          0
48 # define sqlite3_column_text16          0
49 # define sqlite3_complete16             0
50 # define sqlite3_create_collation16     0
51 # define sqlite3_create_function16      0
52 # define sqlite3_errmsg16               0
53 # define sqlite3_open16                 0
54 # define sqlite3_prepare16              0
55 # define sqlite3_prepare16_v2           0
56 # define sqlite3_result_error16         0
57 # define sqlite3_result_text16          0
58 # define sqlite3_result_text16be        0
59 # define sqlite3_result_text16le        0
60 # define sqlite3_value_text16           0
61 # define sqlite3_value_text16be         0
62 # define sqlite3_value_text16le         0
63 # define sqlite3_column_database_name16 0
64 # define sqlite3_column_table_name16    0
65 # define sqlite3_column_origin_name16   0
66 #endif
67 
68 #ifdef SQLITE_OMIT_COMPLETE
69 # define sqlite3_complete 0
70 # define sqlite3_complete16 0
71 #endif
72 
73 #ifdef SQLITE_OMIT_DECLTYPE
74 # define sqlite3_column_decltype16      0
75 # define sqlite3_column_decltype        0
76 #endif
77 
78 #ifdef SQLITE_OMIT_PROGRESS_CALLBACK
79 # define sqlite3_progress_handler 0
80 #endif
81 
82 #ifdef SQLITE_OMIT_VIRTUALTABLE
83 # define sqlite3_create_module 0
84 # define sqlite3_create_module_v2 0
85 # define sqlite3_declare_vtab 0
86 # define sqlite3_vtab_config 0
87 # define sqlite3_vtab_on_conflict 0
88 #endif
89 
90 #ifdef SQLITE_OMIT_SHARED_CACHE
91 # define sqlite3_enable_shared_cache 0
92 #endif
93 
94 #ifdef SQLITE_OMIT_TRACE
95 # define sqlite3_profile       0
96 # define sqlite3_trace         0
97 #endif
98 
99 #ifdef SQLITE_OMIT_GET_TABLE
100 # define sqlite3_free_table    0
101 # define sqlite3_get_table     0
102 #endif
103 
104 #ifdef SQLITE_OMIT_INCRBLOB
105 #define sqlite3_bind_zeroblob  0
106 #define sqlite3_blob_bytes     0
107 #define sqlite3_blob_close     0
108 #define sqlite3_blob_open      0
109 #define sqlite3_blob_read      0
110 #define sqlite3_blob_write     0
111 #define sqlite3_blob_reopen    0
112 #endif
113 
114 /*
115 ** The following structure contains pointers to all SQLite API routines.
116 ** A pointer to this structure is passed into extensions when they are
117 ** loaded so that the extension can make calls back into the SQLite
118 ** library.
119 **
120 ** When adding new APIs, add them to the bottom of this structure
121 ** in order to preserve backwards compatibility.
122 **
123 ** Extensions that use newer APIs should first call the
124 ** sqlite3_libversion_number() to make sure that the API they
125 ** intend to use is supported by the library.  Extensions should
126 ** also check to make sure that the pointer to the function is
127 ** not NULL before calling it.
128 */
129 static const sqlite3_api_routines sqlite3Apis = {
130   sqlite3_aggregate_context,
131 #ifndef SQLITE_OMIT_DEPRECATED
132   sqlite3_aggregate_count,
133 #else
134   0,
135 #endif
136   sqlite3_bind_blob,
137   sqlite3_bind_double,
138   sqlite3_bind_int,
139   sqlite3_bind_int64,
140   sqlite3_bind_null,
141   sqlite3_bind_parameter_count,
142   sqlite3_bind_parameter_index,
143   sqlite3_bind_parameter_name,
144   sqlite3_bind_text,
145   sqlite3_bind_text16,
146   sqlite3_bind_value,
147   sqlite3_busy_handler,
148   sqlite3_busy_timeout,
149   sqlite3_changes,
150   sqlite3_close,
151   sqlite3_collation_needed,
152   sqlite3_collation_needed16,
153   sqlite3_column_blob,
154   sqlite3_column_bytes,
155   sqlite3_column_bytes16,
156   sqlite3_column_count,
157   sqlite3_column_database_name,
158   sqlite3_column_database_name16,
159   sqlite3_column_decltype,
160   sqlite3_column_decltype16,
161   sqlite3_column_double,
162   sqlite3_column_int,
163   sqlite3_column_int64,
164   sqlite3_column_name,
165   sqlite3_column_name16,
166   sqlite3_column_origin_name,
167   sqlite3_column_origin_name16,
168   sqlite3_column_table_name,
169   sqlite3_column_table_name16,
170   sqlite3_column_text,
171   sqlite3_column_text16,
172   sqlite3_column_type,
173   sqlite3_column_value,
174   sqlite3_commit_hook,
175   sqlite3_complete,
176   sqlite3_complete16,
177   sqlite3_create_collation,
178   sqlite3_create_collation16,
179   sqlite3_create_function,
180   sqlite3_create_function16,
181   sqlite3_create_module,
182   sqlite3_data_count,
183   sqlite3_db_handle,
184   sqlite3_declare_vtab,
185   sqlite3_enable_shared_cache,
186   sqlite3_errcode,
187   sqlite3_errmsg,
188   sqlite3_errmsg16,
189   sqlite3_exec,
190 #ifndef SQLITE_OMIT_DEPRECATED
191   sqlite3_expired,
192 #else
193   0,
194 #endif
195   sqlite3_finalize,
196   sqlite3_free,
197   sqlite3_free_table,
198   sqlite3_get_autocommit,
199   sqlite3_get_auxdata,
200   sqlite3_get_table,
201   0,     /* Was sqlite3_global_recover(), but that function is deprecated */
202   sqlite3_interrupt,
203   sqlite3_last_insert_rowid,
204   sqlite3_libversion,
205   sqlite3_libversion_number,
206   sqlite3_malloc,
207   sqlite3_mprintf,
208   sqlite3_open,
209   sqlite3_open16,
210   sqlite3_prepare,
211   sqlite3_prepare16,
212   sqlite3_profile,
213   sqlite3_progress_handler,
214   sqlite3_realloc,
215   sqlite3_reset,
216   sqlite3_result_blob,
217   sqlite3_result_double,
218   sqlite3_result_error,
219   sqlite3_result_error16,
220   sqlite3_result_int,
221   sqlite3_result_int64,
222   sqlite3_result_null,
223   sqlite3_result_text,
224   sqlite3_result_text16,
225   sqlite3_result_text16be,
226   sqlite3_result_text16le,
227   sqlite3_result_value,
228   sqlite3_rollback_hook,
229   sqlite3_set_authorizer,
230   sqlite3_set_auxdata,
231   sqlite3_snprintf,
232   sqlite3_step,
233   sqlite3_table_column_metadata,
234 #ifndef SQLITE_OMIT_DEPRECATED
235   sqlite3_thread_cleanup,
236 #else
237   0,
238 #endif
239   sqlite3_total_changes,
240   sqlite3_trace,
241 #ifndef SQLITE_OMIT_DEPRECATED
242   sqlite3_transfer_bindings,
243 #else
244   0,
245 #endif
246   sqlite3_update_hook,
247   sqlite3_user_data,
248   sqlite3_value_blob,
249   sqlite3_value_bytes,
250   sqlite3_value_bytes16,
251   sqlite3_value_double,
252   sqlite3_value_int,
253   sqlite3_value_int64,
254   sqlite3_value_numeric_type,
255   sqlite3_value_text,
256   sqlite3_value_text16,
257   sqlite3_value_text16be,
258   sqlite3_value_text16le,
259   sqlite3_value_type,
260   sqlite3_vmprintf,
261   /*
262   ** The original API set ends here.  All extensions can call any
263   ** of the APIs above provided that the pointer is not NULL.  But
264   ** before calling APIs that follow, extension should check the
265   ** sqlite3_libversion_number() to make sure they are dealing with
266   ** a library that is new enough to support that API.
267   *************************************************************************
268   */
269   sqlite3_overload_function,
270 
271   /*
272   ** Added after 3.3.13
273   */
274   sqlite3_prepare_v2,
275   sqlite3_prepare16_v2,
276   sqlite3_clear_bindings,
277 
278   /*
279   ** Added for 3.4.1
280   */
281   sqlite3_create_module_v2,
282 
283   /*
284   ** Added for 3.5.0
285   */
286   sqlite3_bind_zeroblob,
287   sqlite3_blob_bytes,
288   sqlite3_blob_close,
289   sqlite3_blob_open,
290   sqlite3_blob_read,
291   sqlite3_blob_write,
292   sqlite3_create_collation_v2,
293   sqlite3_file_control,
294   sqlite3_memory_highwater,
295   sqlite3_memory_used,
296 #ifdef SQLITE_MUTEX_OMIT
297   0,
298   0,
299   0,
300   0,
301   0,
302 #else
303   sqlite3_mutex_alloc,
304   sqlite3_mutex_enter,
305   sqlite3_mutex_free,
306   sqlite3_mutex_leave,
307   sqlite3_mutex_try,
308 #endif
309   sqlite3_open_v2,
310   sqlite3_release_memory,
311   sqlite3_result_error_nomem,
312   sqlite3_result_error_toobig,
313   sqlite3_sleep,
314   sqlite3_soft_heap_limit,
315   sqlite3_vfs_find,
316   sqlite3_vfs_register,
317   sqlite3_vfs_unregister,
318 
319   /*
320   ** Added for 3.5.8
321   */
322   sqlite3_threadsafe,
323   sqlite3_result_zeroblob,
324   sqlite3_result_error_code,
325   sqlite3_test_control,
326   sqlite3_randomness,
327   sqlite3_context_db_handle,
328 
329   /*
330   ** Added for 3.6.0
331   */
332   sqlite3_extended_result_codes,
333   sqlite3_limit,
334   sqlite3_next_stmt,
335   sqlite3_sql,
336   sqlite3_status,
337 
338   /*
339   ** Added for 3.7.4
340   */
341   sqlite3_backup_finish,
342   sqlite3_backup_init,
343   sqlite3_backup_pagecount,
344   sqlite3_backup_remaining,
345   sqlite3_backup_step,
346 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
347   sqlite3_compileoption_get,
348   sqlite3_compileoption_used,
349 #else
350   0,
351   0,
352 #endif
353   sqlite3_create_function_v2,
354   sqlite3_db_config,
355   sqlite3_db_mutex,
356   sqlite3_db_status,
357   sqlite3_extended_errcode,
358   sqlite3_log,
359   sqlite3_soft_heap_limit64,
360   sqlite3_sourceid,
361   sqlite3_stmt_status,
362   sqlite3_strnicmp,
363 #ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
364   sqlite3_unlock_notify,
365 #else
366   0,
367 #endif
368 #ifndef SQLITE_OMIT_WAL
369   sqlite3_wal_autocheckpoint,
370   sqlite3_wal_checkpoint,
371   sqlite3_wal_hook,
372 #else
373   0,
374   0,
375   0,
376 #endif
377   sqlite3_blob_reopen,
378   sqlite3_vtab_config,
379   sqlite3_vtab_on_conflict,
380   sqlite3_close_v2,
381   sqlite3_db_filename,
382   sqlite3_db_readonly,
383   sqlite3_db_release_memory,
384   sqlite3_errstr,
385   sqlite3_stmt_busy,
386   sqlite3_stmt_readonly,
387   sqlite3_stricmp,
388   sqlite3_uri_boolean,
389   sqlite3_uri_int64,
390   sqlite3_uri_parameter,
391   sqlite3_vsnprintf,
392   sqlite3_wal_checkpoint_v2,
393   /* Version 3.8.7 and later */
394   sqlite3_auto_extension,
395   sqlite3_bind_blob64,
396   sqlite3_bind_text64,
397   sqlite3_cancel_auto_extension,
398   sqlite3_load_extension,
399   sqlite3_malloc64,
400   sqlite3_msize,
401   sqlite3_realloc64,
402   sqlite3_reset_auto_extension,
403   sqlite3_result_blob64,
404   sqlite3_result_text64,
405   sqlite3_strglob
406 };
407 
408 /*
409 ** Attempt to load an SQLite extension library contained in the file
410 ** zFile.  The entry point is zProc.  zProc may be 0 in which case a
411 ** default entry point name (sqlite3_extension_init) is used.  Use
412 ** of the default name is recommended.
413 **
414 ** Return SQLITE_OK on success and SQLITE_ERROR if something goes wrong.
415 **
416 ** If an error occurs and pzErrMsg is not 0, then fill *pzErrMsg with
417 ** error message text.  The calling function should free this memory
418 ** by calling sqlite3DbFree(db, ).
419 */
420 static int sqlite3LoadExtension(
421   sqlite3 *db,          /* Load the extension into this database connection */
422   const char *zFile,    /* Name of the shared library containing extension */
423   const char *zProc,    /* Entry point.  Use "sqlite3_extension_init" if 0 */
424   char **pzErrMsg       /* Put error message here if not 0 */
425 ){
426   sqlite3_vfs *pVfs = db->pVfs;
427   void *handle;
428   int (*xInit)(sqlite3*,char**,const sqlite3_api_routines*);
429   char *zErrmsg = 0;
430   const char *zEntry;
431   char *zAltEntry = 0;
432   void **aHandle;
433   int nMsg = 300 + sqlite3Strlen30(zFile);
434   int ii;
435 
436   /* Shared library endings to try if zFile cannot be loaded as written */
437   static const char *azEndings[] = {
438 #if SQLITE_OS_WIN
439      "dll"
440 #elif defined(__APPLE__)
441      "dylib"
442 #else
443      "so"
444 #endif
445   };
446 
447 
448   if( pzErrMsg ) *pzErrMsg = 0;
449 
450   /* Ticket #1863.  To avoid a creating security problems for older
451   ** applications that relink against newer versions of SQLite, the
452   ** ability to run load_extension is turned off by default.  One
453   ** must call sqlite3_enable_load_extension() to turn on extension
454   ** loading.  Otherwise you get the following error.
455   */
456   if( (db->flags & SQLITE_LoadExtension)==0 ){
457     if( pzErrMsg ){
458       *pzErrMsg = sqlite3_mprintf("not authorized");
459     }
460     return SQLITE_ERROR;
461   }
462 
463   zEntry = zProc ? zProc : "sqlite3_extension_init";
464 
465   handle = sqlite3OsDlOpen(pVfs, zFile);
466 #if SQLITE_OS_UNIX || SQLITE_OS_WIN
467   for(ii=0; ii<ArraySize(azEndings) && handle==0; ii++){
468     char *zAltFile = sqlite3_mprintf("%s.%s", zFile, azEndings[ii]);
469     if( zAltFile==0 ) return SQLITE_NOMEM;
470     handle = sqlite3OsDlOpen(pVfs, zAltFile);
471     sqlite3_free(zAltFile);
472   }
473 #endif
474   if( handle==0 ){
475     if( pzErrMsg ){
476       *pzErrMsg = zErrmsg = sqlite3_malloc(nMsg);
477       if( zErrmsg ){
478         sqlite3_snprintf(nMsg, zErrmsg,
479             "unable to open shared library [%s]", zFile);
480         sqlite3OsDlError(pVfs, nMsg-1, zErrmsg);
481       }
482     }
483     return SQLITE_ERROR;
484   }
485   xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
486                    sqlite3OsDlSym(pVfs, handle, zEntry);
487 
488   /* If no entry point was specified and the default legacy
489   ** entry point name "sqlite3_extension_init" was not found, then
490   ** construct an entry point name "sqlite3_X_init" where the X is
491   ** replaced by the lowercase value of every ASCII alphabetic
492   ** character in the filename after the last "/" upto the first ".",
493   ** and eliding the first three characters if they are "lib".
494   ** Examples:
495   **
496   **    /usr/local/lib/libExample5.4.3.so ==>  sqlite3_example_init
497   **    C:/lib/mathfuncs.dll              ==>  sqlite3_mathfuncs_init
498   */
499   if( xInit==0 && zProc==0 ){
500     int iFile, iEntry, c;
501     int ncFile = sqlite3Strlen30(zFile);
502     zAltEntry = sqlite3_malloc(ncFile+30);
503     if( zAltEntry==0 ){
504       sqlite3OsDlClose(pVfs, handle);
505       return SQLITE_NOMEM;
506     }
507     memcpy(zAltEntry, "sqlite3_", 8);
508     for(iFile=ncFile-1; iFile>=0 && zFile[iFile]!='/'; iFile--){}
509     iFile++;
510     if( sqlite3_strnicmp(zFile+iFile, "lib", 3)==0 ) iFile += 3;
511     for(iEntry=8; (c = zFile[iFile])!=0 && c!='.'; iFile++){
512       if( sqlite3Isalpha(c) ){
513         zAltEntry[iEntry++] = (char)sqlite3UpperToLower[(unsigned)c];
514       }
515     }
516     memcpy(zAltEntry+iEntry, "_init", 6);
517     zEntry = zAltEntry;
518     xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
519                      sqlite3OsDlSym(pVfs, handle, zEntry);
520   }
521   if( xInit==0 ){
522     if( pzErrMsg ){
523       nMsg += sqlite3Strlen30(zEntry);
524       *pzErrMsg = zErrmsg = sqlite3_malloc(nMsg);
525       if( zErrmsg ){
526         sqlite3_snprintf(nMsg, zErrmsg,
527             "no entry point [%s] in shared library [%s]", zEntry, zFile);
528         sqlite3OsDlError(pVfs, nMsg-1, zErrmsg);
529       }
530     }
531     sqlite3OsDlClose(pVfs, handle);
532     sqlite3_free(zAltEntry);
533     return SQLITE_ERROR;
534   }
535   sqlite3_free(zAltEntry);
536   if( xInit(db, &zErrmsg, &sqlite3Apis) ){
537     if( pzErrMsg ){
538       *pzErrMsg = sqlite3_mprintf("error during initialization: %s", zErrmsg);
539     }
540     sqlite3_free(zErrmsg);
541     sqlite3OsDlClose(pVfs, handle);
542     return SQLITE_ERROR;
543   }
544 
545   /* Append the new shared library handle to the db->aExtension array. */
546   aHandle = sqlite3DbMallocZero(db, sizeof(handle)*(db->nExtension+1));
547   if( aHandle==0 ){
548     return SQLITE_NOMEM;
549   }
550   if( db->nExtension>0 ){
551     memcpy(aHandle, db->aExtension, sizeof(handle)*db->nExtension);
552   }
553   sqlite3DbFree(db, db->aExtension);
554   db->aExtension = aHandle;
555 
556   db->aExtension[db->nExtension++] = handle;
557   return SQLITE_OK;
558 }
559 int sqlite3_load_extension(
560   sqlite3 *db,          /* Load the extension into this database connection */
561   const char *zFile,    /* Name of the shared library containing extension */
562   const char *zProc,    /* Entry point.  Use "sqlite3_extension_init" if 0 */
563   char **pzErrMsg       /* Put error message here if not 0 */
564 ){
565   int rc;
566   sqlite3_mutex_enter(db->mutex);
567   rc = sqlite3LoadExtension(db, zFile, zProc, pzErrMsg);
568   rc = sqlite3ApiExit(db, rc);
569   sqlite3_mutex_leave(db->mutex);
570   return rc;
571 }
572 
573 /*
574 ** Call this routine when the database connection is closing in order
575 ** to clean up loaded extensions
576 */
577 void sqlite3CloseExtensions(sqlite3 *db){
578   int i;
579   assert( sqlite3_mutex_held(db->mutex) );
580   for(i=0; i<db->nExtension; i++){
581     sqlite3OsDlClose(db->pVfs, db->aExtension[i]);
582   }
583   sqlite3DbFree(db, db->aExtension);
584 }
585 
586 /*
587 ** Enable or disable extension loading.  Extension loading is disabled by
588 ** default so as not to open security holes in older applications.
589 */
590 int sqlite3_enable_load_extension(sqlite3 *db, int onoff){
591   sqlite3_mutex_enter(db->mutex);
592   if( onoff ){
593     db->flags |= SQLITE_LoadExtension;
594   }else{
595     db->flags &= ~SQLITE_LoadExtension;
596   }
597   sqlite3_mutex_leave(db->mutex);
598   return SQLITE_OK;
599 }
600 
601 #endif /* SQLITE_OMIT_LOAD_EXTENSION */
602 
603 /*
604 ** The auto-extension code added regardless of whether or not extension
605 ** loading is supported.  We need a dummy sqlite3Apis pointer for that
606 ** code if regular extension loading is not available.  This is that
607 ** dummy pointer.
608 */
609 #ifdef SQLITE_OMIT_LOAD_EXTENSION
610 static const sqlite3_api_routines sqlite3Apis = { 0 };
611 #endif
612 
613 
614 /*
615 ** The following object holds the list of automatically loaded
616 ** extensions.
617 **
618 ** This list is shared across threads.  The SQLITE_MUTEX_STATIC_MASTER
619 ** mutex must be held while accessing this list.
620 */
621 typedef struct sqlite3AutoExtList sqlite3AutoExtList;
622 static SQLITE_WSD struct sqlite3AutoExtList {
623   int nExt;              /* Number of entries in aExt[] */
624   void (**aExt)(void);   /* Pointers to the extension init functions */
625 } sqlite3Autoext = { 0, 0 };
626 
627 /* The "wsdAutoext" macro will resolve to the autoextension
628 ** state vector.  If writable static data is unsupported on the target,
629 ** we have to locate the state vector at run-time.  In the more common
630 ** case where writable static data is supported, wsdStat can refer directly
631 ** to the "sqlite3Autoext" state vector declared above.
632 */
633 #ifdef SQLITE_OMIT_WSD
634 # define wsdAutoextInit \
635   sqlite3AutoExtList *x = &GLOBAL(sqlite3AutoExtList,sqlite3Autoext)
636 # define wsdAutoext x[0]
637 #else
638 # define wsdAutoextInit
639 # define wsdAutoext sqlite3Autoext
640 #endif
641 
642 
643 /*
644 ** Register a statically linked extension that is automatically
645 ** loaded by every new database connection.
646 */
647 int sqlite3_auto_extension(void (*xInit)(void)){
648   int rc = SQLITE_OK;
649 #ifndef SQLITE_OMIT_AUTOINIT
650   rc = sqlite3_initialize();
651   if( rc ){
652     return rc;
653   }else
654 #endif
655   {
656     int i;
657 #if SQLITE_THREADSAFE
658     sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
659 #endif
660     wsdAutoextInit;
661     sqlite3_mutex_enter(mutex);
662     for(i=0; i<wsdAutoext.nExt; i++){
663       if( wsdAutoext.aExt[i]==xInit ) break;
664     }
665     if( i==wsdAutoext.nExt ){
666       int nByte = (wsdAutoext.nExt+1)*sizeof(wsdAutoext.aExt[0]);
667       void (**aNew)(void);
668       aNew = sqlite3_realloc(wsdAutoext.aExt, nByte);
669       if( aNew==0 ){
670         rc = SQLITE_NOMEM;
671       }else{
672         wsdAutoext.aExt = aNew;
673         wsdAutoext.aExt[wsdAutoext.nExt] = xInit;
674         wsdAutoext.nExt++;
675       }
676     }
677     sqlite3_mutex_leave(mutex);
678     assert( (rc&0xff)==rc );
679     return rc;
680   }
681 }
682 
683 /*
684 ** Cancel a prior call to sqlite3_auto_extension.  Remove xInit from the
685 ** set of routines that is invoked for each new database connection, if it
686 ** is currently on the list.  If xInit is not on the list, then this
687 ** routine is a no-op.
688 **
689 ** Return 1 if xInit was found on the list and removed.  Return 0 if xInit
690 ** was not on the list.
691 */
692 int sqlite3_cancel_auto_extension(void (*xInit)(void)){
693 #if SQLITE_THREADSAFE
694   sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
695 #endif
696   int i;
697   int n = 0;
698   wsdAutoextInit;
699   sqlite3_mutex_enter(mutex);
700   for(i=wsdAutoext.nExt-1; i>=0; i--){
701     if( wsdAutoext.aExt[i]==xInit ){
702       wsdAutoext.nExt--;
703       wsdAutoext.aExt[i] = wsdAutoext.aExt[wsdAutoext.nExt];
704       n++;
705       break;
706     }
707   }
708   sqlite3_mutex_leave(mutex);
709   return n;
710 }
711 
712 /*
713 ** Reset the automatic extension loading mechanism.
714 */
715 void sqlite3_reset_auto_extension(void){
716 #ifndef SQLITE_OMIT_AUTOINIT
717   if( sqlite3_initialize()==SQLITE_OK )
718 #endif
719   {
720 #if SQLITE_THREADSAFE
721     sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
722 #endif
723     wsdAutoextInit;
724     sqlite3_mutex_enter(mutex);
725     sqlite3_free(wsdAutoext.aExt);
726     wsdAutoext.aExt = 0;
727     wsdAutoext.nExt = 0;
728     sqlite3_mutex_leave(mutex);
729   }
730 }
731 
732 /*
733 ** Load all automatic extensions.
734 **
735 ** If anything goes wrong, set an error in the database connection.
736 */
737 void sqlite3AutoLoadExtensions(sqlite3 *db){
738   int i;
739   int go = 1;
740   int rc;
741   int (*xInit)(sqlite3*,char**,const sqlite3_api_routines*);
742 
743   wsdAutoextInit;
744   if( wsdAutoext.nExt==0 ){
745     /* Common case: early out without every having to acquire a mutex */
746     return;
747   }
748   for(i=0; go; i++){
749     char *zErrmsg;
750 #if SQLITE_THREADSAFE
751     sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
752 #endif
753     sqlite3_mutex_enter(mutex);
754     if( i>=wsdAutoext.nExt ){
755       xInit = 0;
756       go = 0;
757     }else{
758       xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
759               wsdAutoext.aExt[i];
760     }
761     sqlite3_mutex_leave(mutex);
762     zErrmsg = 0;
763     if( xInit && (rc = xInit(db, &zErrmsg, &sqlite3Apis))!=0 ){
764       sqlite3ErrorWithMsg(db, rc,
765             "automatic extension loading failed: %s", zErrmsg);
766       go = 0;
767     }
768     sqlite3_free(zErrmsg);
769   }
770 }
771