Annotation of embedaddon/php/ext/sqlite/libsqlite/src/trigger.c, revision 1.1.1.1

1.1       misho       1: /*
                      2: **
                      3: ** The author disclaims copyright to this source code.  In place of
                      4: ** a legal notice, here is a blessing:
                      5: **
                      6: **    May you do good and not evil.
                      7: **    May you find forgiveness for yourself and forgive others.
                      8: **    May you share freely, never taking more than you give.
                      9: **
                     10: *************************************************************************
                     11: *
                     12: */
                     13: #include "sqliteInt.h"
                     14: 
                     15: /*
                     16: ** Delete a linked list of TriggerStep structures.
                     17: */
                     18: void sqliteDeleteTriggerStep(TriggerStep *pTriggerStep){
                     19:   while( pTriggerStep ){
                     20:     TriggerStep * pTmp = pTriggerStep;
                     21:     pTriggerStep = pTriggerStep->pNext;
                     22: 
                     23:     if( pTmp->target.dyn ) sqliteFree((char*)pTmp->target.z);
                     24:     sqliteExprDelete(pTmp->pWhere);
                     25:     sqliteExprListDelete(pTmp->pExprList);
                     26:     sqliteSelectDelete(pTmp->pSelect);
                     27:     sqliteIdListDelete(pTmp->pIdList);
                     28: 
                     29:     sqliteFree(pTmp);
                     30:   }
                     31: }
                     32: 
                     33: /*
                     34: ** This is called by the parser when it sees a CREATE TRIGGER statement
                     35: ** up to the point of the BEGIN before the trigger actions.  A Trigger
                     36: ** structure is generated based on the information available and stored
                     37: ** in pParse->pNewTrigger.  After the trigger actions have been parsed, the
                     38: ** sqliteFinishTrigger() function is called to complete the trigger
                     39: ** construction process.
                     40: */
                     41: void sqliteBeginTrigger(
                     42:   Parse *pParse,      /* The parse context of the CREATE TRIGGER statement */
                     43:   Token *pName,       /* The name of the trigger */
                     44:   int tr_tm,          /* One of TK_BEFORE, TK_AFTER, TK_INSTEAD */
                     45:   int op,             /* One of TK_INSERT, TK_UPDATE, TK_DELETE */
                     46:   IdList *pColumns,   /* column list if this is an UPDATE OF trigger */
                     47:   SrcList *pTableName,/* The name of the table/view the trigger applies to */
                     48:   int foreach,        /* One of TK_ROW or TK_STATEMENT */
                     49:   Expr *pWhen,        /* WHEN clause */
                     50:   int isTemp          /* True if the TEMPORARY keyword is present */
                     51: ){
                     52:   Trigger *nt;
                     53:   Table   *tab;
                     54:   char *zName = 0;        /* Name of the trigger */
                     55:   sqlite *db = pParse->db;
                     56:   int iDb;                /* When database to store the trigger in */
                     57:   DbFixer sFix;
                     58: 
                     59:   /* Check that: 
                     60:   ** 1. the trigger name does not already exist.
                     61:   ** 2. the table (or view) does exist in the same database as the trigger.
                     62:   ** 3. that we are not trying to create a trigger on the sqlite_master table
                     63:   ** 4. That we are not trying to create an INSTEAD OF trigger on a table.
                     64:   ** 5. That we are not trying to create a BEFORE or AFTER trigger on a view.
                     65:   */
                     66:   if( sqlite_malloc_failed ) goto trigger_cleanup;
                     67:   assert( pTableName->nSrc==1 );
                     68:   if( db->init.busy
                     69:    && sqliteFixInit(&sFix, pParse, db->init.iDb, "trigger", pName)
                     70:    && sqliteFixSrcList(&sFix, pTableName)
                     71:   ){
                     72:     goto trigger_cleanup;
                     73:   }
                     74:   tab = sqliteSrcListLookup(pParse, pTableName);
                     75:   if( !tab ){
                     76:     goto trigger_cleanup;
                     77:   }
                     78:   iDb = isTemp ? 1 : tab->iDb;
                     79:   if( iDb>=2 && !db->init.busy ){
                     80:     sqliteErrorMsg(pParse, "triggers may not be added to auxiliary "
                     81:        "database %s", db->aDb[tab->iDb].zName);
                     82:     goto trigger_cleanup;
                     83:   }
                     84: 
                     85:   zName = sqliteStrNDup(pName->z, pName->n);
                     86:   sqliteDequote(zName);
                     87:   if( sqliteHashFind(&(db->aDb[iDb].trigHash), zName,pName->n+1) ){
                     88:     sqliteErrorMsg(pParse, "trigger %T already exists", pName);
                     89:     goto trigger_cleanup;
                     90:   }
                     91:   if( sqliteStrNICmp(tab->zName, "sqlite_", 7)==0 ){
                     92:     sqliteErrorMsg(pParse, "cannot create trigger on system table");
                     93:     pParse->nErr++;
                     94:     goto trigger_cleanup;
                     95:   }
                     96:   if( tab->pSelect && tr_tm != TK_INSTEAD ){
                     97:     sqliteErrorMsg(pParse, "cannot create %s trigger on view: %S", 
                     98:         (tr_tm == TK_BEFORE)?"BEFORE":"AFTER", pTableName, 0);
                     99:     goto trigger_cleanup;
                    100:   }
                    101:   if( !tab->pSelect && tr_tm == TK_INSTEAD ){
                    102:     sqliteErrorMsg(pParse, "cannot create INSTEAD OF"
                    103:         " trigger on table: %S", pTableName, 0);
                    104:     goto trigger_cleanup;
                    105:   }
                    106: #ifndef SQLITE_OMIT_AUTHORIZATION
                    107:   {
                    108:     int code = SQLITE_CREATE_TRIGGER;
                    109:     const char *zDb = db->aDb[tab->iDb].zName;
                    110:     const char *zDbTrig = isTemp ? db->aDb[1].zName : zDb;
                    111:     if( tab->iDb==1 || isTemp ) code = SQLITE_CREATE_TEMP_TRIGGER;
                    112:     if( sqliteAuthCheck(pParse, code, zName, tab->zName, zDbTrig) ){
                    113:       goto trigger_cleanup;
                    114:     }
                    115:     if( sqliteAuthCheck(pParse, SQLITE_INSERT, SCHEMA_TABLE(tab->iDb), 0, zDb)){
                    116:       goto trigger_cleanup;
                    117:     }
                    118:   }
                    119: #endif
                    120: 
                    121:   /* INSTEAD OF triggers can only appear on views and BEGIN triggers
                    122:   ** cannot appear on views.  So we might as well translate every
                    123:   ** INSTEAD OF trigger into a BEFORE trigger.  It simplifies code
                    124:   ** elsewhere.
                    125:   */
                    126:   if (tr_tm == TK_INSTEAD){
                    127:     tr_tm = TK_BEFORE;
                    128:   }
                    129: 
                    130:   /* Build the Trigger object */
                    131:   nt = (Trigger*)sqliteMalloc(sizeof(Trigger));
                    132:   if( nt==0 ) goto trigger_cleanup;
                    133:   nt->name = zName;
                    134:   zName = 0;
                    135:   nt->table = sqliteStrDup(pTableName->a[0].zName);
                    136:   if( sqlite_malloc_failed ) goto trigger_cleanup;
                    137:   nt->iDb = iDb;
                    138:   nt->iTabDb = tab->iDb;
                    139:   nt->op = op;
                    140:   nt->tr_tm = tr_tm;
                    141:   nt->pWhen = sqliteExprDup(pWhen);
                    142:   nt->pColumns = sqliteIdListDup(pColumns);
                    143:   nt->foreach = foreach;
                    144:   sqliteTokenCopy(&nt->nameToken,pName);
                    145:   assert( pParse->pNewTrigger==0 );
                    146:   pParse->pNewTrigger = nt;
                    147: 
                    148: trigger_cleanup:
                    149:   sqliteFree(zName);
                    150:   sqliteSrcListDelete(pTableName);
                    151:   sqliteIdListDelete(pColumns);
                    152:   sqliteExprDelete(pWhen);
                    153: }
                    154: 
                    155: /*
                    156: ** This routine is called after all of the trigger actions have been parsed
                    157: ** in order to complete the process of building the trigger.
                    158: */
                    159: void sqliteFinishTrigger(
                    160:   Parse *pParse,          /* Parser context */
                    161:   TriggerStep *pStepList, /* The triggered program */
                    162:   Token *pAll             /* Token that describes the complete CREATE TRIGGER */
                    163: ){
                    164:   Trigger *nt = 0;          /* The trigger whose construction is finishing up */
                    165:   sqlite *db = pParse->db;  /* The database */
                    166:   DbFixer sFix;
                    167: 
                    168:   if( pParse->nErr || pParse->pNewTrigger==0 ) goto triggerfinish_cleanup;
                    169:   nt = pParse->pNewTrigger;
                    170:   pParse->pNewTrigger = 0;
                    171:   nt->step_list = pStepList;
                    172:   while( pStepList ){
                    173:     pStepList->pTrig = nt;
                    174:     pStepList = pStepList->pNext;
                    175:   }
                    176:   if( sqliteFixInit(&sFix, pParse, nt->iDb, "trigger", &nt->nameToken) 
                    177:           && sqliteFixTriggerStep(&sFix, nt->step_list) ){
                    178:     goto triggerfinish_cleanup;
                    179:   }
                    180: 
                    181:   /* if we are not initializing, and this trigger is not on a TEMP table, 
                    182:   ** build the sqlite_master entry
                    183:   */
                    184:   if( !db->init.busy ){
                    185:     static VdbeOpList insertTrig[] = {
                    186:       { OP_NewRecno,   0, 0,  0          },
                    187:       { OP_String,     0, 0,  "trigger"  },
                    188:       { OP_String,     0, 0,  0          },  /* 2: trigger name */
                    189:       { OP_String,     0, 0,  0          },  /* 3: table name */
                    190:       { OP_Integer,    0, 0,  0          },
                    191:       { OP_String,     0, 0,  0          },  /* 5: SQL */
                    192:       { OP_MakeRecord, 5, 0,  0          },
                    193:       { OP_PutIntKey,  0, 0,  0          },
                    194:     };
                    195:     int addr;
                    196:     Vdbe *v;
                    197: 
                    198:     /* Make an entry in the sqlite_master table */
                    199:     v = sqliteGetVdbe(pParse);
                    200:     if( v==0 ) goto triggerfinish_cleanup;
                    201:     sqliteBeginWriteOperation(pParse, 0, 0);
                    202:     sqliteOpenMasterTable(v, nt->iDb);
                    203:     addr = sqliteVdbeAddOpList(v, ArraySize(insertTrig), insertTrig);
                    204:     sqliteVdbeChangeP3(v, addr+2, nt->name, 0); 
                    205:     sqliteVdbeChangeP3(v, addr+3, nt->table, 0); 
                    206:     sqliteVdbeChangeP3(v, addr+5, pAll->z, pAll->n);
                    207:     if( nt->iDb==0 ){
                    208:       sqliteChangeCookie(db, v);
                    209:     }
                    210:     sqliteVdbeAddOp(v, OP_Close, 0, 0);
                    211:     sqliteEndWriteOperation(pParse);
                    212:   }
                    213: 
                    214:   if( !pParse->explain ){
                    215:     Table *pTab;
                    216:     sqliteHashInsert(&db->aDb[nt->iDb].trigHash, 
                    217:                      nt->name, strlen(nt->name)+1, nt);
                    218:     pTab = sqliteLocateTable(pParse, nt->table, db->aDb[nt->iTabDb].zName);
                    219:     assert( pTab!=0 );
                    220:     nt->pNext = pTab->pTrigger;
                    221:     pTab->pTrigger = nt;
                    222:     nt = 0;
                    223:   }
                    224: 
                    225: triggerfinish_cleanup:
                    226:   sqliteDeleteTrigger(nt);
                    227:   sqliteDeleteTrigger(pParse->pNewTrigger);
                    228:   pParse->pNewTrigger = 0;
                    229:   sqliteDeleteTriggerStep(pStepList);
                    230: }
                    231: 
                    232: /*
                    233: ** Make a copy of all components of the given trigger step.  This has
                    234: ** the effect of copying all Expr.token.z values into memory obtained
                    235: ** from sqliteMalloc().  As initially created, the Expr.token.z values
                    236: ** all point to the input string that was fed to the parser.  But that
                    237: ** string is ephemeral - it will go away as soon as the sqlite_exec()
                    238: ** call that started the parser exits.  This routine makes a persistent
                    239: ** copy of all the Expr.token.z strings so that the TriggerStep structure
                    240: ** will be valid even after the sqlite_exec() call returns.
                    241: */
                    242: static void sqlitePersistTriggerStep(TriggerStep *p){
                    243:   if( p->target.z ){
                    244:     p->target.z = sqliteStrNDup(p->target.z, p->target.n);
                    245:     p->target.dyn = 1;
                    246:   }
                    247:   if( p->pSelect ){
                    248:     Select *pNew = sqliteSelectDup(p->pSelect);
                    249:     sqliteSelectDelete(p->pSelect);
                    250:     p->pSelect = pNew;
                    251:   }
                    252:   if( p->pWhere ){
                    253:     Expr *pNew = sqliteExprDup(p->pWhere);
                    254:     sqliteExprDelete(p->pWhere);
                    255:     p->pWhere = pNew;
                    256:   }
                    257:   if( p->pExprList ){
                    258:     ExprList *pNew = sqliteExprListDup(p->pExprList);
                    259:     sqliteExprListDelete(p->pExprList);
                    260:     p->pExprList = pNew;
                    261:   }
                    262:   if( p->pIdList ){
                    263:     IdList *pNew = sqliteIdListDup(p->pIdList);
                    264:     sqliteIdListDelete(p->pIdList);
                    265:     p->pIdList = pNew;
                    266:   }
                    267: }
                    268: 
                    269: /*
                    270: ** Turn a SELECT statement (that the pSelect parameter points to) into
                    271: ** a trigger step.  Return a pointer to a TriggerStep structure.
                    272: **
                    273: ** The parser calls this routine when it finds a SELECT statement in
                    274: ** body of a TRIGGER.  
                    275: */
                    276: TriggerStep *sqliteTriggerSelectStep(Select *pSelect){
                    277:   TriggerStep *pTriggerStep = sqliteMalloc(sizeof(TriggerStep));
                    278:   if( pTriggerStep==0 ) return 0;
                    279: 
                    280:   pTriggerStep->op = TK_SELECT;
                    281:   pTriggerStep->pSelect = pSelect;
                    282:   pTriggerStep->orconf = OE_Default;
                    283:   sqlitePersistTriggerStep(pTriggerStep);
                    284: 
                    285:   return pTriggerStep;
                    286: }
                    287: 
                    288: /*
                    289: ** Build a trigger step out of an INSERT statement.  Return a pointer
                    290: ** to the new trigger step.
                    291: **
                    292: ** The parser calls this routine when it sees an INSERT inside the
                    293: ** body of a trigger.
                    294: */
                    295: TriggerStep *sqliteTriggerInsertStep(
                    296:   Token *pTableName,  /* Name of the table into which we insert */
                    297:   IdList *pColumn,    /* List of columns in pTableName to insert into */
                    298:   ExprList *pEList,   /* The VALUE clause: a list of values to be inserted */
                    299:   Select *pSelect,    /* A SELECT statement that supplies values */
                    300:   int orconf          /* The conflict algorithm (OE_Abort, OE_Replace, etc.) */
                    301: ){
                    302:   TriggerStep *pTriggerStep = sqliteMalloc(sizeof(TriggerStep));
                    303:   if( pTriggerStep==0 ) return 0;
                    304: 
                    305:   assert(pEList == 0 || pSelect == 0);
                    306:   assert(pEList != 0 || pSelect != 0);
                    307: 
                    308:   pTriggerStep->op = TK_INSERT;
                    309:   pTriggerStep->pSelect = pSelect;
                    310:   pTriggerStep->target  = *pTableName;
                    311:   pTriggerStep->pIdList = pColumn;
                    312:   pTriggerStep->pExprList = pEList;
                    313:   pTriggerStep->orconf = orconf;
                    314:   sqlitePersistTriggerStep(pTriggerStep);
                    315: 
                    316:   return pTriggerStep;
                    317: }
                    318: 
                    319: /*
                    320: ** Construct a trigger step that implements an UPDATE statement and return
                    321: ** a pointer to that trigger step.  The parser calls this routine when it
                    322: ** sees an UPDATE statement inside the body of a CREATE TRIGGER.
                    323: */
                    324: TriggerStep *sqliteTriggerUpdateStep(
                    325:   Token *pTableName,   /* Name of the table to be updated */
                    326:   ExprList *pEList,    /* The SET clause: list of column and new values */
                    327:   Expr *pWhere,        /* The WHERE clause */
                    328:   int orconf           /* The conflict algorithm. (OE_Abort, OE_Ignore, etc) */
                    329: ){
                    330:   TriggerStep *pTriggerStep = sqliteMalloc(sizeof(TriggerStep));
                    331:   if( pTriggerStep==0 ) return 0;
                    332: 
                    333:   pTriggerStep->op = TK_UPDATE;
                    334:   pTriggerStep->target  = *pTableName;
                    335:   pTriggerStep->pExprList = pEList;
                    336:   pTriggerStep->pWhere = pWhere;
                    337:   pTriggerStep->orconf = orconf;
                    338:   sqlitePersistTriggerStep(pTriggerStep);
                    339: 
                    340:   return pTriggerStep;
                    341: }
                    342: 
                    343: /*
                    344: ** Construct a trigger step that implements a DELETE statement and return
                    345: ** a pointer to that trigger step.  The parser calls this routine when it
                    346: ** sees a DELETE statement inside the body of a CREATE TRIGGER.
                    347: */
                    348: TriggerStep *sqliteTriggerDeleteStep(Token *pTableName, Expr *pWhere){
                    349:   TriggerStep *pTriggerStep = sqliteMalloc(sizeof(TriggerStep));
                    350:   if( pTriggerStep==0 ) return 0;
                    351: 
                    352:   pTriggerStep->op = TK_DELETE;
                    353:   pTriggerStep->target  = *pTableName;
                    354:   pTriggerStep->pWhere = pWhere;
                    355:   pTriggerStep->orconf = OE_Default;
                    356:   sqlitePersistTriggerStep(pTriggerStep);
                    357: 
                    358:   return pTriggerStep;
                    359: }
                    360: 
                    361: /* 
                    362: ** Recursively delete a Trigger structure
                    363: */
                    364: void sqliteDeleteTrigger(Trigger *pTrigger){
                    365:   if( pTrigger==0 ) return;
                    366:   sqliteDeleteTriggerStep(pTrigger->step_list);
                    367:   sqliteFree(pTrigger->name);
                    368:   sqliteFree(pTrigger->table);
                    369:   sqliteExprDelete(pTrigger->pWhen);
                    370:   sqliteIdListDelete(pTrigger->pColumns);
                    371:   if( pTrigger->nameToken.dyn ) sqliteFree((char*)pTrigger->nameToken.z);
                    372:   sqliteFree(pTrigger);
                    373: }
                    374: 
                    375: /*
                    376:  * This function is called to drop a trigger from the database schema. 
                    377:  *
                    378:  * This may be called directly from the parser and therefore identifies
                    379:  * the trigger by name.  The sqliteDropTriggerPtr() routine does the
                    380:  * same job as this routine except it take a spointer to the trigger
                    381:  * instead of the trigger name.
                    382:  *
                    383:  * Note that this function does not delete the trigger entirely. Instead it
                    384:  * removes it from the internal schema and places it in the trigDrop hash 
                    385:  * table. This is so that the trigger can be restored into the database schema
                    386:  * if the transaction is rolled back.
                    387:  */
                    388: void sqliteDropTrigger(Parse *pParse, SrcList *pName){
                    389:   Trigger *pTrigger;
                    390:   int i;
                    391:   const char *zDb;
                    392:   const char *zName;
                    393:   int nName;
                    394:   sqlite *db = pParse->db;
                    395: 
                    396:   if( sqlite_malloc_failed ) goto drop_trigger_cleanup;
                    397:   assert( pName->nSrc==1 );
                    398:   zDb = pName->a[0].zDatabase;
                    399:   zName = pName->a[0].zName;
                    400:   nName = strlen(zName);
                    401:   for(i=0; i<db->nDb; i++){
                    402:     int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
                    403:     if( zDb && sqliteStrICmp(db->aDb[j].zName, zDb) ) continue;
                    404:     pTrigger = sqliteHashFind(&(db->aDb[j].trigHash), zName, nName+1);
                    405:     if( pTrigger ) break;
                    406:   }
                    407:   if( !pTrigger ){
                    408:     sqliteErrorMsg(pParse, "no such trigger: %S", pName, 0);
                    409:     goto drop_trigger_cleanup;
                    410:   }
                    411:   sqliteDropTriggerPtr(pParse, pTrigger, 0);
                    412: 
                    413: drop_trigger_cleanup:
                    414:   sqliteSrcListDelete(pName);
                    415: }
                    416: 
                    417: /*
                    418: ** Drop a trigger given a pointer to that trigger.  If nested is false,
                    419: ** then also generate code to remove the trigger from the SQLITE_MASTER
                    420: ** table.
                    421: */
                    422: void sqliteDropTriggerPtr(Parse *pParse, Trigger *pTrigger, int nested){
                    423:   Table   *pTable;
                    424:   Vdbe *v;
                    425:   sqlite *db = pParse->db;
                    426: 
                    427:   assert( pTrigger->iDb<db->nDb );
                    428:   if( pTrigger->iDb>=2 ){
                    429:     sqliteErrorMsg(pParse, "triggers may not be removed from "
                    430:        "auxiliary database %s", db->aDb[pTrigger->iDb].zName);
                    431:     return;
                    432:   }
                    433:   pTable = sqliteFindTable(db, pTrigger->table,db->aDb[pTrigger->iTabDb].zName);
                    434:   assert(pTable);
                    435:   assert( pTable->iDb==pTrigger->iDb || pTrigger->iDb==1 );
                    436: #ifndef SQLITE_OMIT_AUTHORIZATION
                    437:   {
                    438:     int code = SQLITE_DROP_TRIGGER;
                    439:     const char *zDb = db->aDb[pTrigger->iDb].zName;
                    440:     const char *zTab = SCHEMA_TABLE(pTrigger->iDb);
                    441:     if( pTrigger->iDb ) code = SQLITE_DROP_TEMP_TRIGGER;
                    442:     if( sqliteAuthCheck(pParse, code, pTrigger->name, pTable->zName, zDb) ||
                    443:       sqliteAuthCheck(pParse, SQLITE_DELETE, zTab, 0, zDb) ){
                    444:       return;
                    445:     }
                    446:   }
                    447: #endif
                    448: 
                    449:   /* Generate code to destroy the database record of the trigger.
                    450:   */
                    451:   if( pTable!=0 && !nested && (v = sqliteGetVdbe(pParse))!=0 ){
                    452:     int base;
                    453:     static VdbeOpList dropTrigger[] = {
                    454:       { OP_Rewind,     0, ADDR(9),  0},
                    455:       { OP_String,     0, 0,        0}, /* 1 */
                    456:       { OP_Column,     0, 1,        0},
                    457:       { OP_Ne,         0, ADDR(8),  0},
                    458:       { OP_String,     0, 0,        "trigger"},
                    459:       { OP_Column,     0, 0,        0},
                    460:       { OP_Ne,         0, ADDR(8),  0},
                    461:       { OP_Delete,     0, 0,        0},
                    462:       { OP_Next,       0, ADDR(1),  0}, /* 8 */
                    463:     };
                    464: 
                    465:     sqliteBeginWriteOperation(pParse, 0, 0);
                    466:     sqliteOpenMasterTable(v, pTrigger->iDb);
                    467:     base = sqliteVdbeAddOpList(v,  ArraySize(dropTrigger), dropTrigger);
                    468:     sqliteVdbeChangeP3(v, base+1, pTrigger->name, 0);
                    469:     if( pTrigger->iDb==0 ){
                    470:       sqliteChangeCookie(db, v);
                    471:     }
                    472:     sqliteVdbeAddOp(v, OP_Close, 0, 0);
                    473:     sqliteEndWriteOperation(pParse);
                    474:   }
                    475: 
                    476:   /*
                    477:    * If this is not an "explain", then delete the trigger structure.
                    478:    */
                    479:   if( !pParse->explain ){
                    480:     const char *zName = pTrigger->name;
                    481:     int nName = strlen(zName);
                    482:     if( pTable->pTrigger == pTrigger ){
                    483:       pTable->pTrigger = pTrigger->pNext;
                    484:     }else{
                    485:       Trigger *cc = pTable->pTrigger;
                    486:       while( cc ){ 
                    487:         if( cc->pNext == pTrigger ){
                    488:           cc->pNext = cc->pNext->pNext;
                    489:           break;
                    490:         }
                    491:         cc = cc->pNext;
                    492:       }
                    493:       assert(cc);
                    494:     }
                    495:     sqliteHashInsert(&(db->aDb[pTrigger->iDb].trigHash), zName, nName+1, 0);
                    496:     sqliteDeleteTrigger(pTrigger);
                    497:   }
                    498: }
                    499: 
                    500: /*
                    501: ** pEList is the SET clause of an UPDATE statement.  Each entry
                    502: ** in pEList is of the format <id>=<expr>.  If any of the entries
                    503: ** in pEList have an <id> which matches an identifier in pIdList,
                    504: ** then return TRUE.  If pIdList==NULL, then it is considered a
                    505: ** wildcard that matches anything.  Likewise if pEList==NULL then
                    506: ** it matches anything so always return true.  Return false only
                    507: ** if there is no match.
                    508: */
                    509: static int checkColumnOverLap(IdList *pIdList, ExprList *pEList){
                    510:   int e;
                    511:   if( !pIdList || !pEList ) return 1;
                    512:   for(e=0; e<pEList->nExpr; e++){
                    513:     if( sqliteIdListIndex(pIdList, pEList->a[e].zName)>=0 ) return 1;
                    514:   }
                    515:   return 0; 
                    516: }
                    517: 
                    518: /* A global variable that is TRUE if we should always set up temp tables for
                    519:  * for triggers, even if there are no triggers to code. This is used to test 
                    520:  * how much overhead the triggers algorithm is causing.
                    521:  *
                    522:  * This flag can be set or cleared using the "trigger_overhead_test" pragma.
                    523:  * The pragma is not documented since it is not really part of the interface
                    524:  * to SQLite, just the test procedure.
                    525: */
                    526: int always_code_trigger_setup = 0;
                    527: 
                    528: /*
                    529:  * Returns true if a trigger matching op, tr_tm and foreach that is NOT already
                    530:  * on the Parse objects trigger-stack (to prevent recursive trigger firing) is
                    531:  * found in the list specified as pTrigger.
                    532:  */
                    533: int sqliteTriggersExist(
                    534:   Parse *pParse,          /* Used to check for recursive triggers */
                    535:   Trigger *pTrigger,      /* A list of triggers associated with a table */
                    536:   int op,                 /* one of TK_DELETE, TK_INSERT, TK_UPDATE */
                    537:   int tr_tm,              /* one of TK_BEFORE, TK_AFTER */
                    538:   int foreach,            /* one of TK_ROW or TK_STATEMENT */
                    539:   ExprList *pChanges      /* Columns that change in an UPDATE statement */
                    540: ){
                    541:   Trigger * pTriggerCursor;
                    542: 
                    543:   if( always_code_trigger_setup ){
                    544:     return 1;
                    545:   }
                    546: 
                    547:   pTriggerCursor = pTrigger;
                    548:   while( pTriggerCursor ){
                    549:     if( pTriggerCursor->op == op && 
                    550:        pTriggerCursor->tr_tm == tr_tm && 
                    551:        pTriggerCursor->foreach == foreach &&
                    552:        checkColumnOverLap(pTriggerCursor->pColumns, pChanges) ){
                    553:       TriggerStack * ss;
                    554:       ss = pParse->trigStack;
                    555:       while( ss && ss->pTrigger != pTrigger ){
                    556:        ss = ss->pNext;
                    557:       }
                    558:       if( !ss )return 1;
                    559:     }
                    560:     pTriggerCursor = pTriggerCursor->pNext;
                    561:   }
                    562: 
                    563:   return 0;
                    564: }
                    565: 
                    566: /*
                    567: ** Convert the pStep->target token into a SrcList and return a pointer
                    568: ** to that SrcList.
                    569: **
                    570: ** This routine adds a specific database name, if needed, to the target when
                    571: ** forming the SrcList.  This prevents a trigger in one database from
                    572: ** referring to a target in another database.  An exception is when the
                    573: ** trigger is in TEMP in which case it can refer to any other database it
                    574: ** wants.
                    575: */
                    576: static SrcList *targetSrcList(
                    577:   Parse *pParse,       /* The parsing context */
                    578:   TriggerStep *pStep   /* The trigger containing the target token */
                    579: ){
                    580:   Token sDb;           /* Dummy database name token */
                    581:   int iDb;             /* Index of the database to use */
                    582:   SrcList *pSrc;       /* SrcList to be returned */
                    583: 
                    584:   iDb = pStep->pTrig->iDb;
                    585:   if( iDb==0 || iDb>=2 ){
                    586:     assert( iDb<pParse->db->nDb );
                    587:     sDb.z = pParse->db->aDb[iDb].zName;
                    588:     sDb.n = strlen(sDb.z);
                    589:     pSrc = sqliteSrcListAppend(0, &sDb, &pStep->target);
                    590:   } else {
                    591:     pSrc = sqliteSrcListAppend(0, &pStep->target, 0);
                    592:   }
                    593:   return pSrc;
                    594: }
                    595: 
                    596: /*
                    597: ** Generate VDBE code for zero or more statements inside the body of a
                    598: ** trigger.  
                    599: */
                    600: static int codeTriggerProgram(
                    601:   Parse *pParse,            /* The parser context */
                    602:   TriggerStep *pStepList,   /* List of statements inside the trigger body */
                    603:   int orconfin              /* Conflict algorithm. (OE_Abort, etc) */  
                    604: ){
                    605:   TriggerStep * pTriggerStep = pStepList;
                    606:   int orconf;
                    607: 
                    608:   while( pTriggerStep ){
                    609:     int saveNTab = pParse->nTab;
                    610:  
                    611:     orconf = (orconfin == OE_Default)?pTriggerStep->orconf:orconfin;
                    612:     pParse->trigStack->orconf = orconf;
                    613:     switch( pTriggerStep->op ){
                    614:       case TK_SELECT: {
                    615:        Select * ss = sqliteSelectDup(pTriggerStep->pSelect);             
                    616:        assert(ss);
                    617:        assert(ss->pSrc);
                    618:        sqliteSelect(pParse, ss, SRT_Discard, 0, 0, 0, 0);
                    619:        sqliteSelectDelete(ss);
                    620:        break;
                    621:       }
                    622:       case TK_UPDATE: {
                    623:         SrcList *pSrc;
                    624:         pSrc = targetSrcList(pParse, pTriggerStep);
                    625:         sqliteVdbeAddOp(pParse->pVdbe, OP_ListPush, 0, 0);
                    626:         sqliteUpdate(pParse, pSrc,
                    627:                sqliteExprListDup(pTriggerStep->pExprList), 
                    628:                sqliteExprDup(pTriggerStep->pWhere), orconf);
                    629:         sqliteVdbeAddOp(pParse->pVdbe, OP_ListPop, 0, 0);
                    630:         break;
                    631:       }
                    632:       case TK_INSERT: {
                    633:         SrcList *pSrc;
                    634:         pSrc = targetSrcList(pParse, pTriggerStep);
                    635:         sqliteInsert(pParse, pSrc,
                    636:           sqliteExprListDup(pTriggerStep->pExprList), 
                    637:           sqliteSelectDup(pTriggerStep->pSelect), 
                    638:           sqliteIdListDup(pTriggerStep->pIdList), orconf);
                    639:         break;
                    640:       }
                    641:       case TK_DELETE: {
                    642:         SrcList *pSrc;
                    643:         sqliteVdbeAddOp(pParse->pVdbe, OP_ListPush, 0, 0);
                    644:         pSrc = targetSrcList(pParse, pTriggerStep);
                    645:         sqliteDeleteFrom(pParse, pSrc, sqliteExprDup(pTriggerStep->pWhere));
                    646:         sqliteVdbeAddOp(pParse->pVdbe, OP_ListPop, 0, 0);
                    647:         break;
                    648:       }
                    649:       default:
                    650:         assert(0);
                    651:     } 
                    652:     pParse->nTab = saveNTab;
                    653:     pTriggerStep = pTriggerStep->pNext;
                    654:   }
                    655: 
                    656:   return 0;
                    657: }
                    658: 
                    659: /*
                    660: ** This is called to code FOR EACH ROW triggers.
                    661: **
                    662: ** When the code that this function generates is executed, the following 
                    663: ** must be true:
                    664: **
                    665: ** 1. No cursors may be open in the main database.  (But newIdx and oldIdx
                    666: **    can be indices of cursors in temporary tables.  See below.)
                    667: **
                    668: ** 2. If the triggers being coded are ON INSERT or ON UPDATE triggers, then
                    669: **    a temporary vdbe cursor (index newIdx) must be open and pointing at
                    670: **    a row containing values to be substituted for new.* expressions in the
                    671: **    trigger program(s).
                    672: **
                    673: ** 3. If the triggers being coded are ON DELETE or ON UPDATE triggers, then
                    674: **    a temporary vdbe cursor (index oldIdx) must be open and pointing at
                    675: **    a row containing values to be substituted for old.* expressions in the
                    676: **    trigger program(s).
                    677: **
                    678: */
                    679: int sqliteCodeRowTrigger(
                    680:   Parse *pParse,       /* Parse context */
                    681:   int op,              /* One of TK_UPDATE, TK_INSERT, TK_DELETE */
                    682:   ExprList *pChanges,  /* Changes list for any UPDATE OF triggers */
                    683:   int tr_tm,           /* One of TK_BEFORE, TK_AFTER */
                    684:   Table *pTab,         /* The table to code triggers from */
                    685:   int newIdx,          /* The indice of the "new" row to access */
                    686:   int oldIdx,          /* The indice of the "old" row to access */
                    687:   int orconf,          /* ON CONFLICT policy */
                    688:   int ignoreJump       /* Instruction to jump to for RAISE(IGNORE) */
                    689: ){
                    690:   Trigger * pTrigger;
                    691:   TriggerStack * pTriggerStack;
                    692: 
                    693:   assert(op == TK_UPDATE || op == TK_INSERT || op == TK_DELETE);
                    694:   assert(tr_tm == TK_BEFORE || tr_tm == TK_AFTER );
                    695: 
                    696:   assert(newIdx != -1 || oldIdx != -1);
                    697: 
                    698:   pTrigger = pTab->pTrigger;
                    699:   while( pTrigger ){
                    700:     int fire_this = 0;
                    701: 
                    702:     /* determine whether we should code this trigger */
                    703:     if( pTrigger->op == op && pTrigger->tr_tm == tr_tm && 
                    704:         pTrigger->foreach == TK_ROW ){
                    705:       fire_this = 1;
                    706:       pTriggerStack = pParse->trigStack;
                    707:       while( pTriggerStack ){
                    708:         if( pTriggerStack->pTrigger == pTrigger ){
                    709:          fire_this = 0;
                    710:        }
                    711:         pTriggerStack = pTriggerStack->pNext;
                    712:       }
                    713:       if( op == TK_UPDATE && pTrigger->pColumns &&
                    714:           !checkColumnOverLap(pTrigger->pColumns, pChanges) ){
                    715:         fire_this = 0;
                    716:       }
                    717:     }
                    718: 
                    719:     if( fire_this && (pTriggerStack = sqliteMalloc(sizeof(TriggerStack)))!=0 ){
                    720:       int endTrigger;
                    721:       SrcList dummyTablist;
                    722:       Expr * whenExpr;
                    723:       AuthContext sContext;
                    724: 
                    725:       dummyTablist.nSrc = 0;
                    726: 
                    727:       /* Push an entry on to the trigger stack */
                    728:       pTriggerStack->pTrigger = pTrigger;
                    729:       pTriggerStack->newIdx = newIdx;
                    730:       pTriggerStack->oldIdx = oldIdx;
                    731:       pTriggerStack->pTab = pTab;
                    732:       pTriggerStack->pNext = pParse->trigStack;
                    733:       pTriggerStack->ignoreJump = ignoreJump;
                    734:       pParse->trigStack = pTriggerStack;
                    735:       sqliteAuthContextPush(pParse, &sContext, pTrigger->name);
                    736: 
                    737:       /* code the WHEN clause */
                    738:       endTrigger = sqliteVdbeMakeLabel(pParse->pVdbe);
                    739:       whenExpr = sqliteExprDup(pTrigger->pWhen);
                    740:       if( sqliteExprResolveIds(pParse, &dummyTablist, 0, whenExpr) ){
                    741:         pParse->trigStack = pParse->trigStack->pNext;
                    742:         sqliteFree(pTriggerStack);
                    743:         sqliteExprDelete(whenExpr);
                    744:         return 1;
                    745:       }
                    746:       sqliteExprIfFalse(pParse, whenExpr, endTrigger, 1);
                    747:       sqliteExprDelete(whenExpr);
                    748: 
                    749:       sqliteVdbeAddOp(pParse->pVdbe, OP_ContextPush, 0, 0);
                    750:       codeTriggerProgram(pParse, pTrigger->step_list, orconf); 
                    751:       sqliteVdbeAddOp(pParse->pVdbe, OP_ContextPop, 0, 0);
                    752: 
                    753:       /* Pop the entry off the trigger stack */
                    754:       pParse->trigStack = pParse->trigStack->pNext;
                    755:       sqliteAuthContextPop(&sContext);
                    756:       sqliteFree(pTriggerStack);
                    757: 
                    758:       sqliteVdbeResolveLabel(pParse->pVdbe, endTrigger);
                    759:     }
                    760:     pTrigger = pTrigger->pNext;
                    761:   }
                    762: 
                    763:   return 0;
                    764: }

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