xref: /sqlite-3.40.0/src/vtab.c (revision 63b3a64c)
1 /*
2 ** 2006 June 10
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 help implement virtual tables.
13 */
14 #ifndef SQLITE_OMIT_VIRTUALTABLE
15 #include "sqliteInt.h"
16 
17 /*
18 ** Before a virtual table xCreate() or xConnect() method is invoked, the
19 ** sqlite3.pVtabCtx member variable is set to point to an instance of
20 ** this struct allocated on the stack. It is used by the implementation of
21 ** the sqlite3_declare_vtab() and sqlite3_vtab_config() APIs, both of which
22 ** are invoked only from within xCreate and xConnect methods.
23 */
24 struct VtabCtx {
25   VTable *pVTable;    /* The virtual table being constructed */
26   Table *pTab;        /* The Table object to which the virtual table belongs */
27   VtabCtx *pPrior;    /* Parent context (if any) */
28   int bDeclared;      /* True after sqlite3_declare_vtab() is called */
29 };
30 
31 /*
32 ** Construct and install a Module object for a virtual table.  When this
33 ** routine is called, it is guaranteed that all appropriate locks are held
34 ** and the module is not already part of the connection.
35 **
36 ** If there already exists a module with zName, replace it with the new one.
37 ** If pModule==0, then delete the module zName if it exists.
38 */
sqlite3VtabCreateModule(sqlite3 * db,const char * zName,const sqlite3_module * pModule,void * pAux,void (* xDestroy)(void *))39 Module *sqlite3VtabCreateModule(
40   sqlite3 *db,                    /* Database in which module is registered */
41   const char *zName,              /* Name assigned to this module */
42   const sqlite3_module *pModule,  /* The definition of the module */
43   void *pAux,                     /* Context pointer for xCreate/xConnect */
44   void (*xDestroy)(void *)        /* Module destructor function */
45 ){
46   Module *pMod;
47   Module *pDel;
48   char *zCopy;
49   if( pModule==0 ){
50     zCopy = (char*)zName;
51     pMod = 0;
52   }else{
53     int nName = sqlite3Strlen30(zName);
54     pMod = (Module *)sqlite3Malloc(sizeof(Module) + nName + 1);
55     if( pMod==0 ){
56       sqlite3OomFault(db);
57       return 0;
58     }
59     zCopy = (char *)(&pMod[1]);
60     memcpy(zCopy, zName, nName+1);
61     pMod->zName = zCopy;
62     pMod->pModule = pModule;
63     pMod->pAux = pAux;
64     pMod->xDestroy = xDestroy;
65     pMod->pEpoTab = 0;
66     pMod->nRefModule = 1;
67   }
68   pDel = (Module *)sqlite3HashInsert(&db->aModule,zCopy,(void*)pMod);
69   if( pDel ){
70     if( pDel==pMod ){
71       sqlite3OomFault(db);
72       sqlite3DbFree(db, pDel);
73       pMod = 0;
74     }else{
75       sqlite3VtabEponymousTableClear(db, pDel);
76       sqlite3VtabModuleUnref(db, pDel);
77     }
78   }
79   return pMod;
80 }
81 
82 /*
83 ** The actual function that does the work of creating a new module.
84 ** This function implements the sqlite3_create_module() and
85 ** sqlite3_create_module_v2() interfaces.
86 */
createModule(sqlite3 * db,const char * zName,const sqlite3_module * pModule,void * pAux,void (* xDestroy)(void *))87 static int createModule(
88   sqlite3 *db,                    /* Database in which module is registered */
89   const char *zName,              /* Name assigned to this module */
90   const sqlite3_module *pModule,  /* The definition of the module */
91   void *pAux,                     /* Context pointer for xCreate/xConnect */
92   void (*xDestroy)(void *)        /* Module destructor function */
93 ){
94   int rc = SQLITE_OK;
95 
96   sqlite3_mutex_enter(db->mutex);
97   (void)sqlite3VtabCreateModule(db, zName, pModule, pAux, xDestroy);
98   rc = sqlite3ApiExit(db, rc);
99   if( rc!=SQLITE_OK && xDestroy ) xDestroy(pAux);
100   sqlite3_mutex_leave(db->mutex);
101   return rc;
102 }
103 
104 
105 /*
106 ** External API function used to create a new virtual-table module.
107 */
sqlite3_create_module(sqlite3 * db,const char * zName,const sqlite3_module * pModule,void * pAux)108 int sqlite3_create_module(
109   sqlite3 *db,                    /* Database in which module is registered */
110   const char *zName,              /* Name assigned to this module */
111   const sqlite3_module *pModule,  /* The definition of the module */
112   void *pAux                      /* Context pointer for xCreate/xConnect */
113 ){
114 #ifdef SQLITE_ENABLE_API_ARMOR
115   if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
116 #endif
117   return createModule(db, zName, pModule, pAux, 0);
118 }
119 
120 /*
121 ** External API function used to create a new virtual-table module.
122 */
sqlite3_create_module_v2(sqlite3 * db,const char * zName,const sqlite3_module * pModule,void * pAux,void (* xDestroy)(void *))123 int sqlite3_create_module_v2(
124   sqlite3 *db,                    /* Database in which module is registered */
125   const char *zName,              /* Name assigned to this module */
126   const sqlite3_module *pModule,  /* The definition of the module */
127   void *pAux,                     /* Context pointer for xCreate/xConnect */
128   void (*xDestroy)(void *)        /* Module destructor function */
129 ){
130 #ifdef SQLITE_ENABLE_API_ARMOR
131   if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
132 #endif
133   return createModule(db, zName, pModule, pAux, xDestroy);
134 }
135 
136 /*
137 ** External API to drop all virtual-table modules, except those named
138 ** on the azNames list.
139 */
sqlite3_drop_modules(sqlite3 * db,const char ** azNames)140 int sqlite3_drop_modules(sqlite3 *db, const char** azNames){
141   HashElem *pThis, *pNext;
142 #ifdef SQLITE_ENABLE_API_ARMOR
143   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
144 #endif
145   for(pThis=sqliteHashFirst(&db->aModule); pThis; pThis=pNext){
146     Module *pMod = (Module*)sqliteHashData(pThis);
147     pNext = sqliteHashNext(pThis);
148     if( azNames ){
149       int ii;
150       for(ii=0; azNames[ii]!=0 && strcmp(azNames[ii],pMod->zName)!=0; ii++){}
151       if( azNames[ii]!=0 ) continue;
152     }
153     createModule(db, pMod->zName, 0, 0, 0);
154   }
155   return SQLITE_OK;
156 }
157 
158 /*
159 ** Decrement the reference count on a Module object.  Destroy the
160 ** module when the reference count reaches zero.
161 */
sqlite3VtabModuleUnref(sqlite3 * db,Module * pMod)162 void sqlite3VtabModuleUnref(sqlite3 *db, Module *pMod){
163   assert( pMod->nRefModule>0 );
164   pMod->nRefModule--;
165   if( pMod->nRefModule==0 ){
166     if( pMod->xDestroy ){
167       pMod->xDestroy(pMod->pAux);
168     }
169     assert( pMod->pEpoTab==0 );
170     sqlite3DbFree(db, pMod);
171   }
172 }
173 
174 /*
175 ** Lock the virtual table so that it cannot be disconnected.
176 ** Locks nest.  Every lock should have a corresponding unlock.
177 ** If an unlock is omitted, resources leaks will occur.
178 **
179 ** If a disconnect is attempted while a virtual table is locked,
180 ** the disconnect is deferred until all locks have been removed.
181 */
sqlite3VtabLock(VTable * pVTab)182 void sqlite3VtabLock(VTable *pVTab){
183   pVTab->nRef++;
184 }
185 
186 
187 /*
188 ** pTab is a pointer to a Table structure representing a virtual-table.
189 ** Return a pointer to the VTable object used by connection db to access
190 ** this virtual-table, if one has been created, or NULL otherwise.
191 */
sqlite3GetVTable(sqlite3 * db,Table * pTab)192 VTable *sqlite3GetVTable(sqlite3 *db, Table *pTab){
193   VTable *pVtab;
194   assert( IsVirtual(pTab) );
195   for(pVtab=pTab->u.vtab.p; pVtab && pVtab->db!=db; pVtab=pVtab->pNext);
196   return pVtab;
197 }
198 
199 /*
200 ** Decrement the ref-count on a virtual table object. When the ref-count
201 ** reaches zero, call the xDisconnect() method to delete the object.
202 */
sqlite3VtabUnlock(VTable * pVTab)203 void sqlite3VtabUnlock(VTable *pVTab){
204   sqlite3 *db = pVTab->db;
205 
206   assert( db );
207   assert( pVTab->nRef>0 );
208   assert( db->eOpenState==SQLITE_STATE_OPEN
209        || db->eOpenState==SQLITE_STATE_ZOMBIE );
210 
211   pVTab->nRef--;
212   if( pVTab->nRef==0 ){
213     sqlite3_vtab *p = pVTab->pVtab;
214     sqlite3VtabModuleUnref(pVTab->db, pVTab->pMod);
215     if( p ){
216       p->pModule->xDisconnect(p);
217     }
218     sqlite3DbFree(db, pVTab);
219   }
220 }
221 
222 /*
223 ** Table p is a virtual table. This function moves all elements in the
224 ** p->u.vtab.p list to the sqlite3.pDisconnect lists of their associated
225 ** database connections to be disconnected at the next opportunity.
226 ** Except, if argument db is not NULL, then the entry associated with
227 ** connection db is left in the p->u.vtab.p list.
228 */
vtabDisconnectAll(sqlite3 * db,Table * p)229 static VTable *vtabDisconnectAll(sqlite3 *db, Table *p){
230   VTable *pRet = 0;
231   VTable *pVTable;
232 
233   assert( IsVirtual(p) );
234   pVTable = p->u.vtab.p;
235   p->u.vtab.p = 0;
236 
237   /* Assert that the mutex (if any) associated with the BtShared database
238   ** that contains table p is held by the caller. See header comments
239   ** above function sqlite3VtabUnlockList() for an explanation of why
240   ** this makes it safe to access the sqlite3.pDisconnect list of any
241   ** database connection that may have an entry in the p->u.vtab.p list.
242   */
243   assert( db==0 || sqlite3SchemaMutexHeld(db, 0, p->pSchema) );
244 
245   while( pVTable ){
246     sqlite3 *db2 = pVTable->db;
247     VTable *pNext = pVTable->pNext;
248     assert( db2 );
249     if( db2==db ){
250       pRet = pVTable;
251       p->u.vtab.p = pRet;
252       pRet->pNext = 0;
253     }else{
254       pVTable->pNext = db2->pDisconnect;
255       db2->pDisconnect = pVTable;
256     }
257     pVTable = pNext;
258   }
259 
260   assert( !db || pRet );
261   return pRet;
262 }
263 
264 /*
265 ** Table *p is a virtual table. This function removes the VTable object
266 ** for table *p associated with database connection db from the linked
267 ** list in p->pVTab. It also decrements the VTable ref count. This is
268 ** used when closing database connection db to free all of its VTable
269 ** objects without disturbing the rest of the Schema object (which may
270 ** be being used by other shared-cache connections).
271 */
sqlite3VtabDisconnect(sqlite3 * db,Table * p)272 void sqlite3VtabDisconnect(sqlite3 *db, Table *p){
273   VTable **ppVTab;
274 
275   assert( IsVirtual(p) );
276   assert( sqlite3BtreeHoldsAllMutexes(db) );
277   assert( sqlite3_mutex_held(db->mutex) );
278 
279   for(ppVTab=&p->u.vtab.p; *ppVTab; ppVTab=&(*ppVTab)->pNext){
280     if( (*ppVTab)->db==db  ){
281       VTable *pVTab = *ppVTab;
282       *ppVTab = pVTab->pNext;
283       sqlite3VtabUnlock(pVTab);
284       break;
285     }
286   }
287 }
288 
289 
290 /*
291 ** Disconnect all the virtual table objects in the sqlite3.pDisconnect list.
292 **
293 ** This function may only be called when the mutexes associated with all
294 ** shared b-tree databases opened using connection db are held by the
295 ** caller. This is done to protect the sqlite3.pDisconnect list. The
296 ** sqlite3.pDisconnect list is accessed only as follows:
297 **
298 **   1) By this function. In this case, all BtShared mutexes and the mutex
299 **      associated with the database handle itself must be held.
300 **
301 **   2) By function vtabDisconnectAll(), when it adds a VTable entry to
302 **      the sqlite3.pDisconnect list. In this case either the BtShared mutex
303 **      associated with the database the virtual table is stored in is held
304 **      or, if the virtual table is stored in a non-sharable database, then
305 **      the database handle mutex is held.
306 **
307 ** As a result, a sqlite3.pDisconnect cannot be accessed simultaneously
308 ** by multiple threads. It is thread-safe.
309 */
sqlite3VtabUnlockList(sqlite3 * db)310 void sqlite3VtabUnlockList(sqlite3 *db){
311   VTable *p = db->pDisconnect;
312 
313   assert( sqlite3BtreeHoldsAllMutexes(db) );
314   assert( sqlite3_mutex_held(db->mutex) );
315 
316   if( p ){
317     db->pDisconnect = 0;
318     sqlite3ExpirePreparedStatements(db, 0);
319     do {
320       VTable *pNext = p->pNext;
321       sqlite3VtabUnlock(p);
322       p = pNext;
323     }while( p );
324   }
325 }
326 
327 /*
328 ** Clear any and all virtual-table information from the Table record.
329 ** This routine is called, for example, just before deleting the Table
330 ** record.
331 **
332 ** Since it is a virtual-table, the Table structure contains a pointer
333 ** to the head of a linked list of VTable structures. Each VTable
334 ** structure is associated with a single sqlite3* user of the schema.
335 ** The reference count of the VTable structure associated with database
336 ** connection db is decremented immediately (which may lead to the
337 ** structure being xDisconnected and free). Any other VTable structures
338 ** in the list are moved to the sqlite3.pDisconnect list of the associated
339 ** database connection.
340 */
sqlite3VtabClear(sqlite3 * db,Table * p)341 void sqlite3VtabClear(sqlite3 *db, Table *p){
342   assert( IsVirtual(p) );
343   assert( db!=0 );
344   if( db->pnBytesFreed==0 ) vtabDisconnectAll(0, p);
345   if( p->u.vtab.azArg ){
346     int i;
347     for(i=0; i<p->u.vtab.nArg; i++){
348       if( i!=1 ) sqlite3DbFree(db, p->u.vtab.azArg[i]);
349     }
350     sqlite3DbFree(db, p->u.vtab.azArg);
351   }
352 }
353 
354 /*
355 ** Add a new module argument to pTable->u.vtab.azArg[].
356 ** The string is not copied - the pointer is stored.  The
357 ** string will be freed automatically when the table is
358 ** deleted.
359 */
addModuleArgument(Parse * pParse,Table * pTable,char * zArg)360 static void addModuleArgument(Parse *pParse, Table *pTable, char *zArg){
361   sqlite3_int64 nBytes;
362   char **azModuleArg;
363   sqlite3 *db = pParse->db;
364 
365   assert( IsVirtual(pTable) );
366   nBytes = sizeof(char *)*(2+pTable->u.vtab.nArg);
367   if( pTable->u.vtab.nArg+3>=db->aLimit[SQLITE_LIMIT_COLUMN] ){
368     sqlite3ErrorMsg(pParse, "too many columns on %s", pTable->zName);
369   }
370   azModuleArg = sqlite3DbRealloc(db, pTable->u.vtab.azArg, nBytes);
371   if( azModuleArg==0 ){
372     sqlite3DbFree(db, zArg);
373   }else{
374     int i = pTable->u.vtab.nArg++;
375     azModuleArg[i] = zArg;
376     azModuleArg[i+1] = 0;
377     pTable->u.vtab.azArg = azModuleArg;
378   }
379 }
380 
381 /*
382 ** The parser calls this routine when it first sees a CREATE VIRTUAL TABLE
383 ** statement.  The module name has been parsed, but the optional list
384 ** of parameters that follow the module name are still pending.
385 */
sqlite3VtabBeginParse(Parse * pParse,Token * pName1,Token * pName2,Token * pModuleName,int ifNotExists)386 void sqlite3VtabBeginParse(
387   Parse *pParse,        /* Parsing context */
388   Token *pName1,        /* Name of new table, or database name */
389   Token *pName2,        /* Name of new table or NULL */
390   Token *pModuleName,   /* Name of the module for the virtual table */
391   int ifNotExists       /* No error if the table already exists */
392 ){
393   Table *pTable;        /* The new virtual table */
394   sqlite3 *db;          /* Database connection */
395 
396   sqlite3StartTable(pParse, pName1, pName2, 0, 0, 1, ifNotExists);
397   pTable = pParse->pNewTable;
398   if( pTable==0 ) return;
399   assert( 0==pTable->pIndex );
400   pTable->eTabType = TABTYP_VTAB;
401 
402   db = pParse->db;
403 
404   assert( pTable->u.vtab.nArg==0 );
405   addModuleArgument(pParse, pTable, sqlite3NameFromToken(db, pModuleName));
406   addModuleArgument(pParse, pTable, 0);
407   addModuleArgument(pParse, pTable, sqlite3DbStrDup(db, pTable->zName));
408   assert( (pParse->sNameToken.z==pName2->z && pName2->z!=0)
409        || (pParse->sNameToken.z==pName1->z && pName2->z==0)
410   );
411   pParse->sNameToken.n = (int)(
412       &pModuleName->z[pModuleName->n] - pParse->sNameToken.z
413   );
414 
415 #ifndef SQLITE_OMIT_AUTHORIZATION
416   /* Creating a virtual table invokes the authorization callback twice.
417   ** The first invocation, to obtain permission to INSERT a row into the
418   ** sqlite_schema table, has already been made by sqlite3StartTable().
419   ** The second call, to obtain permission to create the table, is made now.
420   */
421   if( pTable->u.vtab.azArg ){
422     int iDb = sqlite3SchemaToIndex(db, pTable->pSchema);
423     assert( iDb>=0 ); /* The database the table is being created in */
424     sqlite3AuthCheck(pParse, SQLITE_CREATE_VTABLE, pTable->zName,
425             pTable->u.vtab.azArg[0], pParse->db->aDb[iDb].zDbSName);
426   }
427 #endif
428 }
429 
430 /*
431 ** This routine takes the module argument that has been accumulating
432 ** in pParse->zArg[] and appends it to the list of arguments on the
433 ** virtual table currently under construction in pParse->pTable.
434 */
addArgumentToVtab(Parse * pParse)435 static void addArgumentToVtab(Parse *pParse){
436   if( pParse->sArg.z && pParse->pNewTable ){
437     const char *z = (const char*)pParse->sArg.z;
438     int n = pParse->sArg.n;
439     sqlite3 *db = pParse->db;
440     addModuleArgument(pParse, pParse->pNewTable, sqlite3DbStrNDup(db, z, n));
441   }
442 }
443 
444 /*
445 ** The parser calls this routine after the CREATE VIRTUAL TABLE statement
446 ** has been completely parsed.
447 */
sqlite3VtabFinishParse(Parse * pParse,Token * pEnd)448 void sqlite3VtabFinishParse(Parse *pParse, Token *pEnd){
449   Table *pTab = pParse->pNewTable;  /* The table being constructed */
450   sqlite3 *db = pParse->db;         /* The database connection */
451 
452   if( pTab==0 ) return;
453   assert( IsVirtual(pTab) );
454   addArgumentToVtab(pParse);
455   pParse->sArg.z = 0;
456   if( pTab->u.vtab.nArg<1 ) return;
457 
458   /* If the CREATE VIRTUAL TABLE statement is being entered for the
459   ** first time (in other words if the virtual table is actually being
460   ** created now instead of just being read out of sqlite_schema) then
461   ** do additional initialization work and store the statement text
462   ** in the sqlite_schema table.
463   */
464   if( !db->init.busy ){
465     char *zStmt;
466     char *zWhere;
467     int iDb;
468     int iReg;
469     Vdbe *v;
470 
471     sqlite3MayAbort(pParse);
472 
473     /* Compute the complete text of the CREATE VIRTUAL TABLE statement */
474     if( pEnd ){
475       pParse->sNameToken.n = (int)(pEnd->z - pParse->sNameToken.z) + pEnd->n;
476     }
477     zStmt = sqlite3MPrintf(db, "CREATE VIRTUAL TABLE %T", &pParse->sNameToken);
478 
479     /* A slot for the record has already been allocated in the
480     ** schema table.  We just need to update that slot with all
481     ** the information we've collected.
482     **
483     ** The VM register number pParse->regRowid holds the rowid of an
484     ** entry in the sqlite_schema table tht was created for this vtab
485     ** by sqlite3StartTable().
486     */
487     iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
488     sqlite3NestedParse(pParse,
489       "UPDATE %Q." LEGACY_SCHEMA_TABLE " "
490          "SET type='table', name=%Q, tbl_name=%Q, rootpage=0, sql=%Q "
491        "WHERE rowid=#%d",
492       db->aDb[iDb].zDbSName,
493       pTab->zName,
494       pTab->zName,
495       zStmt,
496       pParse->regRowid
497     );
498     v = sqlite3GetVdbe(pParse);
499     sqlite3ChangeCookie(pParse, iDb);
500 
501     sqlite3VdbeAddOp0(v, OP_Expire);
502     zWhere = sqlite3MPrintf(db, "name=%Q AND sql=%Q", pTab->zName, zStmt);
503     sqlite3VdbeAddParseSchemaOp(v, iDb, zWhere, 0);
504     sqlite3DbFree(db, zStmt);
505 
506     iReg = ++pParse->nMem;
507     sqlite3VdbeLoadString(v, iReg, pTab->zName);
508     sqlite3VdbeAddOp2(v, OP_VCreate, iDb, iReg);
509   }else{
510     /* If we are rereading the sqlite_schema table create the in-memory
511     ** record of the table. */
512     Table *pOld;
513     Schema *pSchema = pTab->pSchema;
514     const char *zName = pTab->zName;
515     assert( zName!=0 );
516     sqlite3MarkAllShadowTablesOf(db, pTab);
517     pOld = sqlite3HashInsert(&pSchema->tblHash, zName, pTab);
518     if( pOld ){
519       sqlite3OomFault(db);
520       assert( pTab==pOld );  /* Malloc must have failed inside HashInsert() */
521       return;
522     }
523     pParse->pNewTable = 0;
524   }
525 }
526 
527 /*
528 ** The parser calls this routine when it sees the first token
529 ** of an argument to the module name in a CREATE VIRTUAL TABLE statement.
530 */
sqlite3VtabArgInit(Parse * pParse)531 void sqlite3VtabArgInit(Parse *pParse){
532   addArgumentToVtab(pParse);
533   pParse->sArg.z = 0;
534   pParse->sArg.n = 0;
535 }
536 
537 /*
538 ** The parser calls this routine for each token after the first token
539 ** in an argument to the module name in a CREATE VIRTUAL TABLE statement.
540 */
sqlite3VtabArgExtend(Parse * pParse,Token * p)541 void sqlite3VtabArgExtend(Parse *pParse, Token *p){
542   Token *pArg = &pParse->sArg;
543   if( pArg->z==0 ){
544     pArg->z = p->z;
545     pArg->n = p->n;
546   }else{
547     assert(pArg->z <= p->z);
548     pArg->n = (int)(&p->z[p->n] - pArg->z);
549   }
550 }
551 
552 /*
553 ** Invoke a virtual table constructor (either xCreate or xConnect). The
554 ** pointer to the function to invoke is passed as the fourth parameter
555 ** to this procedure.
556 */
vtabCallConstructor(sqlite3 * db,Table * pTab,Module * pMod,int (* xConstruct)(sqlite3 *,void *,int,const char * const *,sqlite3_vtab **,char **),char ** pzErr)557 static int vtabCallConstructor(
558   sqlite3 *db,
559   Table *pTab,
560   Module *pMod,
561   int (*xConstruct)(sqlite3*,void*,int,const char*const*,sqlite3_vtab**,char**),
562   char **pzErr
563 ){
564   VtabCtx sCtx;
565   VTable *pVTable;
566   int rc;
567   const char *const*azArg;
568   int nArg = pTab->u.vtab.nArg;
569   char *zErr = 0;
570   char *zModuleName;
571   int iDb;
572   VtabCtx *pCtx;
573 
574   assert( IsVirtual(pTab) );
575   azArg = (const char *const*)pTab->u.vtab.azArg;
576 
577   /* Check that the virtual-table is not already being initialized */
578   for(pCtx=db->pVtabCtx; pCtx; pCtx=pCtx->pPrior){
579     if( pCtx->pTab==pTab ){
580       *pzErr = sqlite3MPrintf(db,
581           "vtable constructor called recursively: %s", pTab->zName
582       );
583       return SQLITE_LOCKED;
584     }
585   }
586 
587   zModuleName = sqlite3DbStrDup(db, pTab->zName);
588   if( !zModuleName ){
589     return SQLITE_NOMEM_BKPT;
590   }
591 
592   pVTable = sqlite3MallocZero(sizeof(VTable));
593   if( !pVTable ){
594     sqlite3OomFault(db);
595     sqlite3DbFree(db, zModuleName);
596     return SQLITE_NOMEM_BKPT;
597   }
598   pVTable->db = db;
599   pVTable->pMod = pMod;
600   pVTable->eVtabRisk = SQLITE_VTABRISK_Normal;
601 
602   iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
603   pTab->u.vtab.azArg[1] = db->aDb[iDb].zDbSName;
604 
605   /* Invoke the virtual table constructor */
606   assert( &db->pVtabCtx );
607   assert( xConstruct );
608   sCtx.pTab = pTab;
609   sCtx.pVTable = pVTable;
610   sCtx.pPrior = db->pVtabCtx;
611   sCtx.bDeclared = 0;
612   db->pVtabCtx = &sCtx;
613   rc = xConstruct(db, pMod->pAux, nArg, azArg, &pVTable->pVtab, &zErr);
614   db->pVtabCtx = sCtx.pPrior;
615   if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
616   assert( sCtx.pTab==pTab );
617 
618   if( SQLITE_OK!=rc ){
619     if( zErr==0 ){
620       *pzErr = sqlite3MPrintf(db, "vtable constructor failed: %s", zModuleName);
621     }else {
622       *pzErr = sqlite3MPrintf(db, "%s", zErr);
623       sqlite3_free(zErr);
624     }
625     sqlite3DbFree(db, pVTable);
626   }else if( ALWAYS(pVTable->pVtab) ){
627     /* Justification of ALWAYS():  A correct vtab constructor must allocate
628     ** the sqlite3_vtab object if successful.  */
629     memset(pVTable->pVtab, 0, sizeof(pVTable->pVtab[0]));
630     pVTable->pVtab->pModule = pMod->pModule;
631     pMod->nRefModule++;
632     pVTable->nRef = 1;
633     if( sCtx.bDeclared==0 ){
634       const char *zFormat = "vtable constructor did not declare schema: %s";
635       *pzErr = sqlite3MPrintf(db, zFormat, pTab->zName);
636       sqlite3VtabUnlock(pVTable);
637       rc = SQLITE_ERROR;
638     }else{
639       int iCol;
640       u16 oooHidden = 0;
641       /* If everything went according to plan, link the new VTable structure
642       ** into the linked list headed by pTab->u.vtab.p. Then loop through the
643       ** columns of the table to see if any of them contain the token "hidden".
644       ** If so, set the Column COLFLAG_HIDDEN flag and remove the token from
645       ** the type string.  */
646       pVTable->pNext = pTab->u.vtab.p;
647       pTab->u.vtab.p = pVTable;
648 
649       for(iCol=0; iCol<pTab->nCol; iCol++){
650         char *zType = sqlite3ColumnType(&pTab->aCol[iCol], "");
651         int nType;
652         int i = 0;
653         nType = sqlite3Strlen30(zType);
654         for(i=0; i<nType; i++){
655           if( 0==sqlite3StrNICmp("hidden", &zType[i], 6)
656            && (i==0 || zType[i-1]==' ')
657            && (zType[i+6]=='\0' || zType[i+6]==' ')
658           ){
659             break;
660           }
661         }
662         if( i<nType ){
663           int j;
664           int nDel = 6 + (zType[i+6] ? 1 : 0);
665           for(j=i; (j+nDel)<=nType; j++){
666             zType[j] = zType[j+nDel];
667           }
668           if( zType[i]=='\0' && i>0 ){
669             assert(zType[i-1]==' ');
670             zType[i-1] = '\0';
671           }
672           pTab->aCol[iCol].colFlags |= COLFLAG_HIDDEN;
673           pTab->tabFlags |= TF_HasHidden;
674           oooHidden = TF_OOOHidden;
675         }else{
676           pTab->tabFlags |= oooHidden;
677         }
678       }
679     }
680   }
681 
682   sqlite3DbFree(db, zModuleName);
683   return rc;
684 }
685 
686 /*
687 ** This function is invoked by the parser to call the xConnect() method
688 ** of the virtual table pTab. If an error occurs, an error code is returned
689 ** and an error left in pParse.
690 **
691 ** This call is a no-op if table pTab is not a virtual table.
692 */
sqlite3VtabCallConnect(Parse * pParse,Table * pTab)693 int sqlite3VtabCallConnect(Parse *pParse, Table *pTab){
694   sqlite3 *db = pParse->db;
695   const char *zMod;
696   Module *pMod;
697   int rc;
698 
699   assert( pTab );
700   assert( IsVirtual(pTab) );
701   if( sqlite3GetVTable(db, pTab) ){
702     return SQLITE_OK;
703   }
704 
705   /* Locate the required virtual table module */
706   zMod = pTab->u.vtab.azArg[0];
707   pMod = (Module*)sqlite3HashFind(&db->aModule, zMod);
708 
709   if( !pMod ){
710     const char *zModule = pTab->u.vtab.azArg[0];
711     sqlite3ErrorMsg(pParse, "no such module: %s", zModule);
712     rc = SQLITE_ERROR;
713   }else{
714     char *zErr = 0;
715     rc = vtabCallConstructor(db, pTab, pMod, pMod->pModule->xConnect, &zErr);
716     if( rc!=SQLITE_OK ){
717       sqlite3ErrorMsg(pParse, "%s", zErr);
718       pParse->rc = rc;
719     }
720     sqlite3DbFree(db, zErr);
721   }
722 
723   return rc;
724 }
725 /*
726 ** Grow the db->aVTrans[] array so that there is room for at least one
727 ** more v-table. Return SQLITE_NOMEM if a malloc fails, or SQLITE_OK otherwise.
728 */
growVTrans(sqlite3 * db)729 static int growVTrans(sqlite3 *db){
730   const int ARRAY_INCR = 5;
731 
732   /* Grow the sqlite3.aVTrans array if required */
733   if( (db->nVTrans%ARRAY_INCR)==0 ){
734     VTable **aVTrans;
735     sqlite3_int64 nBytes = sizeof(sqlite3_vtab*)*
736                                  ((sqlite3_int64)db->nVTrans + ARRAY_INCR);
737     aVTrans = sqlite3DbRealloc(db, (void *)db->aVTrans, nBytes);
738     if( !aVTrans ){
739       return SQLITE_NOMEM_BKPT;
740     }
741     memset(&aVTrans[db->nVTrans], 0, sizeof(sqlite3_vtab *)*ARRAY_INCR);
742     db->aVTrans = aVTrans;
743   }
744 
745   return SQLITE_OK;
746 }
747 
748 /*
749 ** Add the virtual table pVTab to the array sqlite3.aVTrans[]. Space should
750 ** have already been reserved using growVTrans().
751 */
addToVTrans(sqlite3 * db,VTable * pVTab)752 static void addToVTrans(sqlite3 *db, VTable *pVTab){
753   /* Add pVtab to the end of sqlite3.aVTrans */
754   db->aVTrans[db->nVTrans++] = pVTab;
755   sqlite3VtabLock(pVTab);
756 }
757 
758 /*
759 ** This function is invoked by the vdbe to call the xCreate method
760 ** of the virtual table named zTab in database iDb.
761 **
762 ** If an error occurs, *pzErr is set to point to an English language
763 ** description of the error and an SQLITE_XXX error code is returned.
764 ** In this case the caller must call sqlite3DbFree(db, ) on *pzErr.
765 */
sqlite3VtabCallCreate(sqlite3 * db,int iDb,const char * zTab,char ** pzErr)766 int sqlite3VtabCallCreate(sqlite3 *db, int iDb, const char *zTab, char **pzErr){
767   int rc = SQLITE_OK;
768   Table *pTab;
769   Module *pMod;
770   const char *zMod;
771 
772   pTab = sqlite3FindTable(db, zTab, db->aDb[iDb].zDbSName);
773   assert( pTab && IsVirtual(pTab) && !pTab->u.vtab.p );
774 
775   /* Locate the required virtual table module */
776   zMod = pTab->u.vtab.azArg[0];
777   pMod = (Module*)sqlite3HashFind(&db->aModule, zMod);
778 
779   /* If the module has been registered and includes a Create method,
780   ** invoke it now. If the module has not been registered, return an
781   ** error. Otherwise, do nothing.
782   */
783   if( pMod==0 || pMod->pModule->xCreate==0 || pMod->pModule->xDestroy==0 ){
784     *pzErr = sqlite3MPrintf(db, "no such module: %s", zMod);
785     rc = SQLITE_ERROR;
786   }else{
787     rc = vtabCallConstructor(db, pTab, pMod, pMod->pModule->xCreate, pzErr);
788   }
789 
790   /* Justification of ALWAYS():  The xConstructor method is required to
791   ** create a valid sqlite3_vtab if it returns SQLITE_OK. */
792   if( rc==SQLITE_OK && ALWAYS(sqlite3GetVTable(db, pTab)) ){
793     rc = growVTrans(db);
794     if( rc==SQLITE_OK ){
795       addToVTrans(db, sqlite3GetVTable(db, pTab));
796     }
797   }
798 
799   return rc;
800 }
801 
802 /*
803 ** This function is used to set the schema of a virtual table.  It is only
804 ** valid to call this function from within the xCreate() or xConnect() of a
805 ** virtual table module.
806 */
sqlite3_declare_vtab(sqlite3 * db,const char * zCreateTable)807 int sqlite3_declare_vtab(sqlite3 *db, const char *zCreateTable){
808   VtabCtx *pCtx;
809   int rc = SQLITE_OK;
810   Table *pTab;
811   Parse sParse;
812   int initBusy;
813 
814 #ifdef SQLITE_ENABLE_API_ARMOR
815   if( !sqlite3SafetyCheckOk(db) || zCreateTable==0 ){
816     return SQLITE_MISUSE_BKPT;
817   }
818 #endif
819   sqlite3_mutex_enter(db->mutex);
820   pCtx = db->pVtabCtx;
821   if( !pCtx || pCtx->bDeclared ){
822     sqlite3Error(db, SQLITE_MISUSE);
823     sqlite3_mutex_leave(db->mutex);
824     return SQLITE_MISUSE_BKPT;
825   }
826   pTab = pCtx->pTab;
827   assert( IsVirtual(pTab) );
828 
829   sqlite3ParseObjectInit(&sParse, db);
830   sParse.eParseMode = PARSE_MODE_DECLARE_VTAB;
831   sParse.disableTriggers = 1;
832   /* We should never be able to reach this point while loading the
833   ** schema.  Nevertheless, defend against that (turn off db->init.busy)
834   ** in case a bug arises. */
835   assert( db->init.busy==0 );
836   initBusy = db->init.busy;
837   db->init.busy = 0;
838   sParse.nQueryLoop = 1;
839   if( SQLITE_OK==sqlite3RunParser(&sParse, zCreateTable)
840    && ALWAYS(sParse.pNewTable!=0)
841    && ALWAYS(!db->mallocFailed)
842    && IsOrdinaryTable(sParse.pNewTable)
843   ){
844     assert( sParse.zErrMsg==0 );
845     if( !pTab->aCol ){
846       Table *pNew = sParse.pNewTable;
847       Index *pIdx;
848       pTab->aCol = pNew->aCol;
849       sqlite3ExprListDelete(db, pNew->u.tab.pDfltList);
850       pTab->nNVCol = pTab->nCol = pNew->nCol;
851       pTab->tabFlags |= pNew->tabFlags & (TF_WithoutRowid|TF_NoVisibleRowid);
852       pNew->nCol = 0;
853       pNew->aCol = 0;
854       assert( pTab->pIndex==0 );
855       assert( HasRowid(pNew) || sqlite3PrimaryKeyIndex(pNew)!=0 );
856       if( !HasRowid(pNew)
857        && pCtx->pVTable->pMod->pModule->xUpdate!=0
858        && sqlite3PrimaryKeyIndex(pNew)->nKeyCol!=1
859       ){
860         /* WITHOUT ROWID virtual tables must either be read-only (xUpdate==0)
861         ** or else must have a single-column PRIMARY KEY */
862         rc = SQLITE_ERROR;
863       }
864       pIdx = pNew->pIndex;
865       if( pIdx ){
866         assert( pIdx->pNext==0 );
867         pTab->pIndex = pIdx;
868         pNew->pIndex = 0;
869         pIdx->pTable = pTab;
870       }
871     }
872     pCtx->bDeclared = 1;
873   }else{
874     sqlite3ErrorWithMsg(db, SQLITE_ERROR,
875           (sParse.zErrMsg ? "%s" : 0), sParse.zErrMsg);
876     sqlite3DbFree(db, sParse.zErrMsg);
877     rc = SQLITE_ERROR;
878   }
879   sParse.eParseMode = PARSE_MODE_NORMAL;
880 
881   if( sParse.pVdbe ){
882     sqlite3VdbeFinalize(sParse.pVdbe);
883   }
884   sqlite3DeleteTable(db, sParse.pNewTable);
885   sqlite3ParseObjectReset(&sParse);
886   db->init.busy = initBusy;
887 
888   assert( (rc&0xff)==rc );
889   rc = sqlite3ApiExit(db, rc);
890   sqlite3_mutex_leave(db->mutex);
891   return rc;
892 }
893 
894 /*
895 ** This function is invoked by the vdbe to call the xDestroy method
896 ** of the virtual table named zTab in database iDb. This occurs
897 ** when a DROP TABLE is mentioned.
898 **
899 ** This call is a no-op if zTab is not a virtual table.
900 */
sqlite3VtabCallDestroy(sqlite3 * db,int iDb,const char * zTab)901 int sqlite3VtabCallDestroy(sqlite3 *db, int iDb, const char *zTab){
902   int rc = SQLITE_OK;
903   Table *pTab;
904 
905   pTab = sqlite3FindTable(db, zTab, db->aDb[iDb].zDbSName);
906   if( ALWAYS(pTab!=0)
907    && ALWAYS(IsVirtual(pTab))
908    && ALWAYS(pTab->u.vtab.p!=0)
909   ){
910     VTable *p;
911     int (*xDestroy)(sqlite3_vtab *);
912     for(p=pTab->u.vtab.p; p; p=p->pNext){
913       assert( p->pVtab );
914       if( p->pVtab->nRef>0 ){
915         return SQLITE_LOCKED;
916       }
917     }
918     p = vtabDisconnectAll(db, pTab);
919     xDestroy = p->pMod->pModule->xDestroy;
920     if( xDestroy==0 ) xDestroy = p->pMod->pModule->xDisconnect;
921     assert( xDestroy!=0 );
922     pTab->nTabRef++;
923     rc = xDestroy(p->pVtab);
924     /* Remove the sqlite3_vtab* from the aVTrans[] array, if applicable */
925     if( rc==SQLITE_OK ){
926       assert( pTab->u.vtab.p==p && p->pNext==0 );
927       p->pVtab = 0;
928       pTab->u.vtab.p = 0;
929       sqlite3VtabUnlock(p);
930     }
931     sqlite3DeleteTable(db, pTab);
932   }
933 
934   return rc;
935 }
936 
937 /*
938 ** This function invokes either the xRollback or xCommit method
939 ** of each of the virtual tables in the sqlite3.aVTrans array. The method
940 ** called is identified by the second argument, "offset", which is
941 ** the offset of the method to call in the sqlite3_module structure.
942 **
943 ** The array is cleared after invoking the callbacks.
944 */
callFinaliser(sqlite3 * db,int offset)945 static void callFinaliser(sqlite3 *db, int offset){
946   int i;
947   if( db->aVTrans ){
948     VTable **aVTrans = db->aVTrans;
949     db->aVTrans = 0;
950     for(i=0; i<db->nVTrans; i++){
951       VTable *pVTab = aVTrans[i];
952       sqlite3_vtab *p = pVTab->pVtab;
953       if( p ){
954         int (*x)(sqlite3_vtab *);
955         x = *(int (**)(sqlite3_vtab *))((char *)p->pModule + offset);
956         if( x ) x(p);
957       }
958       pVTab->iSavepoint = 0;
959       sqlite3VtabUnlock(pVTab);
960     }
961     sqlite3DbFree(db, aVTrans);
962     db->nVTrans = 0;
963   }
964 }
965 
966 /*
967 ** Invoke the xSync method of all virtual tables in the sqlite3.aVTrans
968 ** array. Return the error code for the first error that occurs, or
969 ** SQLITE_OK if all xSync operations are successful.
970 **
971 ** If an error message is available, leave it in p->zErrMsg.
972 */
sqlite3VtabSync(sqlite3 * db,Vdbe * p)973 int sqlite3VtabSync(sqlite3 *db, Vdbe *p){
974   int i;
975   int rc = SQLITE_OK;
976   VTable **aVTrans = db->aVTrans;
977 
978   db->aVTrans = 0;
979   for(i=0; rc==SQLITE_OK && i<db->nVTrans; i++){
980     int (*x)(sqlite3_vtab *);
981     sqlite3_vtab *pVtab = aVTrans[i]->pVtab;
982     if( pVtab && (x = pVtab->pModule->xSync)!=0 ){
983       rc = x(pVtab);
984       sqlite3VtabImportErrmsg(p, pVtab);
985     }
986   }
987   db->aVTrans = aVTrans;
988   return rc;
989 }
990 
991 /*
992 ** Invoke the xRollback method of all virtual tables in the
993 ** sqlite3.aVTrans array. Then clear the array itself.
994 */
sqlite3VtabRollback(sqlite3 * db)995 int sqlite3VtabRollback(sqlite3 *db){
996   callFinaliser(db, offsetof(sqlite3_module,xRollback));
997   return SQLITE_OK;
998 }
999 
1000 /*
1001 ** Invoke the xCommit method of all virtual tables in the
1002 ** sqlite3.aVTrans array. Then clear the array itself.
1003 */
sqlite3VtabCommit(sqlite3 * db)1004 int sqlite3VtabCommit(sqlite3 *db){
1005   callFinaliser(db, offsetof(sqlite3_module,xCommit));
1006   return SQLITE_OK;
1007 }
1008 
1009 /*
1010 ** If the virtual table pVtab supports the transaction interface
1011 ** (xBegin/xRollback/xCommit and optionally xSync) and a transaction is
1012 ** not currently open, invoke the xBegin method now.
1013 **
1014 ** If the xBegin call is successful, place the sqlite3_vtab pointer
1015 ** in the sqlite3.aVTrans array.
1016 */
sqlite3VtabBegin(sqlite3 * db,VTable * pVTab)1017 int sqlite3VtabBegin(sqlite3 *db, VTable *pVTab){
1018   int rc = SQLITE_OK;
1019   const sqlite3_module *pModule;
1020 
1021   /* Special case: If db->aVTrans is NULL and db->nVTrans is greater
1022   ** than zero, then this function is being called from within a
1023   ** virtual module xSync() callback. It is illegal to write to
1024   ** virtual module tables in this case, so return SQLITE_LOCKED.
1025   */
1026   if( sqlite3VtabInSync(db) ){
1027     return SQLITE_LOCKED;
1028   }
1029   if( !pVTab ){
1030     return SQLITE_OK;
1031   }
1032   pModule = pVTab->pVtab->pModule;
1033 
1034   if( pModule->xBegin ){
1035     int i;
1036 
1037     /* If pVtab is already in the aVTrans array, return early */
1038     for(i=0; i<db->nVTrans; i++){
1039       if( db->aVTrans[i]==pVTab ){
1040         return SQLITE_OK;
1041       }
1042     }
1043 
1044     /* Invoke the xBegin method. If successful, add the vtab to the
1045     ** sqlite3.aVTrans[] array. */
1046     rc = growVTrans(db);
1047     if( rc==SQLITE_OK ){
1048       rc = pModule->xBegin(pVTab->pVtab);
1049       if( rc==SQLITE_OK ){
1050         int iSvpt = db->nStatement + db->nSavepoint;
1051         addToVTrans(db, pVTab);
1052         if( iSvpt && pModule->xSavepoint ){
1053           pVTab->iSavepoint = iSvpt;
1054           rc = pModule->xSavepoint(pVTab->pVtab, iSvpt-1);
1055         }
1056       }
1057     }
1058   }
1059   return rc;
1060 }
1061 
1062 /*
1063 ** Invoke either the xSavepoint, xRollbackTo or xRelease method of all
1064 ** virtual tables that currently have an open transaction. Pass iSavepoint
1065 ** as the second argument to the virtual table method invoked.
1066 **
1067 ** If op is SAVEPOINT_BEGIN, the xSavepoint method is invoked. If it is
1068 ** SAVEPOINT_ROLLBACK, the xRollbackTo method. Otherwise, if op is
1069 ** SAVEPOINT_RELEASE, then the xRelease method of each virtual table with
1070 ** an open transaction is invoked.
1071 **
1072 ** If any virtual table method returns an error code other than SQLITE_OK,
1073 ** processing is abandoned and the error returned to the caller of this
1074 ** function immediately. If all calls to virtual table methods are successful,
1075 ** SQLITE_OK is returned.
1076 */
sqlite3VtabSavepoint(sqlite3 * db,int op,int iSavepoint)1077 int sqlite3VtabSavepoint(sqlite3 *db, int op, int iSavepoint){
1078   int rc = SQLITE_OK;
1079 
1080   assert( op==SAVEPOINT_RELEASE||op==SAVEPOINT_ROLLBACK||op==SAVEPOINT_BEGIN );
1081   assert( iSavepoint>=-1 );
1082   if( db->aVTrans ){
1083     int i;
1084     for(i=0; rc==SQLITE_OK && i<db->nVTrans; i++){
1085       VTable *pVTab = db->aVTrans[i];
1086       const sqlite3_module *pMod = pVTab->pMod->pModule;
1087       if( pVTab->pVtab && pMod->iVersion>=2 ){
1088         int (*xMethod)(sqlite3_vtab *, int);
1089         sqlite3VtabLock(pVTab);
1090         switch( op ){
1091           case SAVEPOINT_BEGIN:
1092             xMethod = pMod->xSavepoint;
1093             pVTab->iSavepoint = iSavepoint+1;
1094             break;
1095           case SAVEPOINT_ROLLBACK:
1096             xMethod = pMod->xRollbackTo;
1097             break;
1098           default:
1099             xMethod = pMod->xRelease;
1100             break;
1101         }
1102         if( xMethod && pVTab->iSavepoint>iSavepoint ){
1103           rc = xMethod(pVTab->pVtab, iSavepoint);
1104         }
1105         sqlite3VtabUnlock(pVTab);
1106       }
1107     }
1108   }
1109   return rc;
1110 }
1111 
1112 /*
1113 ** The first parameter (pDef) is a function implementation.  The
1114 ** second parameter (pExpr) is the first argument to this function.
1115 ** If pExpr is a column in a virtual table, then let the virtual
1116 ** table implementation have an opportunity to overload the function.
1117 **
1118 ** This routine is used to allow virtual table implementations to
1119 ** overload MATCH, LIKE, GLOB, and REGEXP operators.
1120 **
1121 ** Return either the pDef argument (indicating no change) or a
1122 ** new FuncDef structure that is marked as ephemeral using the
1123 ** SQLITE_FUNC_EPHEM flag.
1124 */
sqlite3VtabOverloadFunction(sqlite3 * db,FuncDef * pDef,int nArg,Expr * pExpr)1125 FuncDef *sqlite3VtabOverloadFunction(
1126   sqlite3 *db,    /* Database connection for reporting malloc problems */
1127   FuncDef *pDef,  /* Function to possibly overload */
1128   int nArg,       /* Number of arguments to the function */
1129   Expr *pExpr     /* First argument to the function */
1130 ){
1131   Table *pTab;
1132   sqlite3_vtab *pVtab;
1133   sqlite3_module *pMod;
1134   void (*xSFunc)(sqlite3_context*,int,sqlite3_value**) = 0;
1135   void *pArg = 0;
1136   FuncDef *pNew;
1137   int rc = 0;
1138 
1139   /* Check to see the left operand is a column in a virtual table */
1140   if( NEVER(pExpr==0) ) return pDef;
1141   if( pExpr->op!=TK_COLUMN ) return pDef;
1142   assert( ExprUseYTab(pExpr) );
1143   pTab = pExpr->y.pTab;
1144   if( NEVER(pTab==0) ) return pDef;
1145   if( !IsVirtual(pTab) ) return pDef;
1146   pVtab = sqlite3GetVTable(db, pTab)->pVtab;
1147   assert( pVtab!=0 );
1148   assert( pVtab->pModule!=0 );
1149   pMod = (sqlite3_module *)pVtab->pModule;
1150   if( pMod->xFindFunction==0 ) return pDef;
1151 
1152   /* Call the xFindFunction method on the virtual table implementation
1153   ** to see if the implementation wants to overload this function.
1154   **
1155   ** Though undocumented, we have historically always invoked xFindFunction
1156   ** with an all lower-case function name.  Continue in this tradition to
1157   ** avoid any chance of an incompatibility.
1158   */
1159 #ifdef SQLITE_DEBUG
1160   {
1161     int i;
1162     for(i=0; pDef->zName[i]; i++){
1163       unsigned char x = (unsigned char)pDef->zName[i];
1164       assert( x==sqlite3UpperToLower[x] );
1165     }
1166   }
1167 #endif
1168   rc = pMod->xFindFunction(pVtab, nArg, pDef->zName, &xSFunc, &pArg);
1169   if( rc==0 ){
1170     return pDef;
1171   }
1172 
1173   /* Create a new ephemeral function definition for the overloaded
1174   ** function */
1175   pNew = sqlite3DbMallocZero(db, sizeof(*pNew)
1176                              + sqlite3Strlen30(pDef->zName) + 1);
1177   if( pNew==0 ){
1178     return pDef;
1179   }
1180   *pNew = *pDef;
1181   pNew->zName = (const char*)&pNew[1];
1182   memcpy((char*)&pNew[1], pDef->zName, sqlite3Strlen30(pDef->zName)+1);
1183   pNew->xSFunc = xSFunc;
1184   pNew->pUserData = pArg;
1185   pNew->funcFlags |= SQLITE_FUNC_EPHEM;
1186   return pNew;
1187 }
1188 
1189 /*
1190 ** Make sure virtual table pTab is contained in the pParse->apVirtualLock[]
1191 ** array so that an OP_VBegin will get generated for it.  Add pTab to the
1192 ** array if it is missing.  If pTab is already in the array, this routine
1193 ** is a no-op.
1194 */
sqlite3VtabMakeWritable(Parse * pParse,Table * pTab)1195 void sqlite3VtabMakeWritable(Parse *pParse, Table *pTab){
1196   Parse *pToplevel = sqlite3ParseToplevel(pParse);
1197   int i, n;
1198   Table **apVtabLock;
1199 
1200   assert( IsVirtual(pTab) );
1201   for(i=0; i<pToplevel->nVtabLock; i++){
1202     if( pTab==pToplevel->apVtabLock[i] ) return;
1203   }
1204   n = (pToplevel->nVtabLock+1)*sizeof(pToplevel->apVtabLock[0]);
1205   apVtabLock = sqlite3Realloc(pToplevel->apVtabLock, n);
1206   if( apVtabLock ){
1207     pToplevel->apVtabLock = apVtabLock;
1208     pToplevel->apVtabLock[pToplevel->nVtabLock++] = pTab;
1209   }else{
1210     sqlite3OomFault(pToplevel->db);
1211   }
1212 }
1213 
1214 /*
1215 ** Check to see if virtual table module pMod can be have an eponymous
1216 ** virtual table instance.  If it can, create one if one does not already
1217 ** exist. Return non-zero if either the eponymous virtual table instance
1218 ** exists when this routine returns or if an attempt to create it failed
1219 ** and an error message was left in pParse.
1220 **
1221 ** An eponymous virtual table instance is one that is named after its
1222 ** module, and more importantly, does not require a CREATE VIRTUAL TABLE
1223 ** statement in order to come into existance.  Eponymous virtual table
1224 ** instances always exist.  They cannot be DROP-ed.
1225 **
1226 ** Any virtual table module for which xConnect and xCreate are the same
1227 ** method can have an eponymous virtual table instance.
1228 */
sqlite3VtabEponymousTableInit(Parse * pParse,Module * pMod)1229 int sqlite3VtabEponymousTableInit(Parse *pParse, Module *pMod){
1230   const sqlite3_module *pModule = pMod->pModule;
1231   Table *pTab;
1232   char *zErr = 0;
1233   int rc;
1234   sqlite3 *db = pParse->db;
1235   if( pMod->pEpoTab ) return 1;
1236   if( pModule->xCreate!=0 && pModule->xCreate!=pModule->xConnect ) return 0;
1237   pTab = sqlite3DbMallocZero(db, sizeof(Table));
1238   if( pTab==0 ) return 0;
1239   pTab->zName = sqlite3DbStrDup(db, pMod->zName);
1240   if( pTab->zName==0 ){
1241     sqlite3DbFree(db, pTab);
1242     return 0;
1243   }
1244   pMod->pEpoTab = pTab;
1245   pTab->nTabRef = 1;
1246   pTab->eTabType = TABTYP_VTAB;
1247   pTab->pSchema = db->aDb[0].pSchema;
1248   assert( pTab->u.vtab.nArg==0 );
1249   pTab->iPKey = -1;
1250   pTab->tabFlags |= TF_Eponymous;
1251   addModuleArgument(pParse, pTab, sqlite3DbStrDup(db, pTab->zName));
1252   addModuleArgument(pParse, pTab, 0);
1253   addModuleArgument(pParse, pTab, sqlite3DbStrDup(db, pTab->zName));
1254   rc = vtabCallConstructor(db, pTab, pMod, pModule->xConnect, &zErr);
1255   if( rc ){
1256     sqlite3ErrorMsg(pParse, "%s", zErr);
1257     sqlite3DbFree(db, zErr);
1258     sqlite3VtabEponymousTableClear(db, pMod);
1259   }
1260   return 1;
1261 }
1262 
1263 /*
1264 ** Erase the eponymous virtual table instance associated with
1265 ** virtual table module pMod, if it exists.
1266 */
sqlite3VtabEponymousTableClear(sqlite3 * db,Module * pMod)1267 void sqlite3VtabEponymousTableClear(sqlite3 *db, Module *pMod){
1268   Table *pTab = pMod->pEpoTab;
1269   if( pTab!=0 ){
1270     /* Mark the table as Ephemeral prior to deleting it, so that the
1271     ** sqlite3DeleteTable() routine will know that it is not stored in
1272     ** the schema. */
1273     pTab->tabFlags |= TF_Ephemeral;
1274     sqlite3DeleteTable(db, pTab);
1275     pMod->pEpoTab = 0;
1276   }
1277 }
1278 
1279 /*
1280 ** Return the ON CONFLICT resolution mode in effect for the virtual
1281 ** table update operation currently in progress.
1282 **
1283 ** The results of this routine are undefined unless it is called from
1284 ** within an xUpdate method.
1285 */
sqlite3_vtab_on_conflict(sqlite3 * db)1286 int sqlite3_vtab_on_conflict(sqlite3 *db){
1287   static const unsigned char aMap[] = {
1288     SQLITE_ROLLBACK, SQLITE_ABORT, SQLITE_FAIL, SQLITE_IGNORE, SQLITE_REPLACE
1289   };
1290 #ifdef SQLITE_ENABLE_API_ARMOR
1291   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
1292 #endif
1293   assert( OE_Rollback==1 && OE_Abort==2 && OE_Fail==3 );
1294   assert( OE_Ignore==4 && OE_Replace==5 );
1295   assert( db->vtabOnConflict>=1 && db->vtabOnConflict<=5 );
1296   return (int)aMap[db->vtabOnConflict-1];
1297 }
1298 
1299 /*
1300 ** Call from within the xCreate() or xConnect() methods to provide
1301 ** the SQLite core with additional information about the behavior
1302 ** of the virtual table being implemented.
1303 */
sqlite3_vtab_config(sqlite3 * db,int op,...)1304 int sqlite3_vtab_config(sqlite3 *db, int op, ...){
1305   va_list ap;
1306   int rc = SQLITE_OK;
1307   VtabCtx *p;
1308 
1309 #ifdef SQLITE_ENABLE_API_ARMOR
1310   if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
1311 #endif
1312   sqlite3_mutex_enter(db->mutex);
1313   p = db->pVtabCtx;
1314   if( !p ){
1315     rc = SQLITE_MISUSE_BKPT;
1316   }else{
1317     assert( p->pTab==0 || IsVirtual(p->pTab) );
1318     va_start(ap, op);
1319     switch( op ){
1320       case SQLITE_VTAB_CONSTRAINT_SUPPORT: {
1321         p->pVTable->bConstraint = (u8)va_arg(ap, int);
1322         break;
1323       }
1324       case SQLITE_VTAB_INNOCUOUS: {
1325         p->pVTable->eVtabRisk = SQLITE_VTABRISK_Low;
1326         break;
1327       }
1328       case SQLITE_VTAB_DIRECTONLY: {
1329         p->pVTable->eVtabRisk = SQLITE_VTABRISK_High;
1330         break;
1331       }
1332       default: {
1333         rc = SQLITE_MISUSE_BKPT;
1334         break;
1335       }
1336     }
1337     va_end(ap);
1338   }
1339 
1340   if( rc!=SQLITE_OK ) sqlite3Error(db, rc);
1341   sqlite3_mutex_leave(db->mutex);
1342   return rc;
1343 }
1344 
1345 #endif /* SQLITE_OMIT_VIRTUALTABLE */
1346