src/trigger.c

   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 ** This file contains the implementation for TRIGGERs
  12 */
  13 #include "sqliteInt.h"
  14
  15 #ifndef SQLITE_OMIT_TRIGGER
  16 /*
  17 ** Delete a linked list of TriggerStep structures.
  18 */
  19 void sqlite3DeleteTriggerStep(sqlite3 *db, TriggerStep *pTriggerStep){
  20   while( pTriggerStep ){
  21     TriggerStep * pTmp = pTriggerStep;
  22     pTriggerStep = pTriggerStep->pNext;
  23
  24     sqlite3ExprDelete(db, pTmp->pWhere);
  25     sqlite3ExprListDelete(db, pTmp->pExprList);
  26     sqlite3SelectDelete(db, pTmp->pSelect);
  27     sqlite3IdListDelete(db, pTmp->pIdList);
  28     sqlite3UpsertDelete(db, pTmp->pUpsert);
  29     sqlite3DbFree(db, pTmp->zSpan);
  30
  31     sqlite3DbFree(db, pTmp);
  32   }
  33 }
  34
  35 /*
  36 ** Given table pTab, return a list of all the triggers attached to
  37 ** the table. The list is connected by Trigger.pNext pointers.
  38 **
  39 ** All of the triggers on pTab that are in the same database as pTab
  40 ** are already attached to pTab->pTrigger.  But there might be additional
  41 ** triggers on pTab in the TEMP schema.  This routine prepends all
  42 ** TEMP triggers on pTab to the beginning of the pTab->pTrigger list
  43 ** and returns the combined list.
  44 **
  45 ** To state it another way:  This routine returns a list of all triggers
  46 ** that fire off of pTab.  The list will include any TEMP triggers on
  47 ** pTab as well as the triggers lised in pTab->pTrigger.
  48 */
  49 Trigger *sqlite3TriggerList(Parse *pParse, Table *pTab){
  50   Schema * const pTmpSchema = pParse->db->aDb[1].pSchema;
  51   Trigger *pList = 0;                  /* List of triggers to return */
  52
  53   if( pParse->disableTriggers ){
  54     return 0;
  55   }
  56
  57   if( pTmpSchema!=pTab->pSchema ){
  58     HashElem *p;
  59     assert( sqlite3SchemaMutexHeld(pParse->db, 0, pTmpSchema) );
  60     for(p=sqliteHashFirst(&pTmpSchema->trigHash); p; p=sqliteHashNext(p)){
  61       Trigger *pTrig = (Trigger *)sqliteHashData(p);
  62       if( pTrig->pTabSchema==pTab->pSchema
  63        && 0==sqlite3StrICmp(pTrig->table, pTab->zName)
  64       ){
  65         pTrig->pNext = (pList ? pList : pTab->pTrigger);
  66         pList = pTrig;
  67       }
  68     }
  69   }
  70
  71   return (pList ? pList : pTab->pTrigger);
  72 }
  73
  74 /*
  75 ** This is called by the parser when it sees a CREATE TRIGGER statement
  76 ** up to the point of the BEGIN before the trigger actions.  A Trigger
  77 ** structure is generated based on the information available and stored
  78 ** in pParse->pNewTrigger.  After the trigger actions have been parsed, the
  79 ** sqlite3FinishTrigger() function is called to complete the trigger
  80 ** construction process.
  81 */
  82 void sqlite3BeginTrigger(
  83   Parse *pParse,      /* The parse context of the CREATE TRIGGER statement */
  84   Token *pName1,      /* The name of the trigger */
  85   Token *pName2,      /* The name of the trigger */
  86   int tr_tm,          /* One of TK_BEFORE, TK_AFTER, TK_INSTEAD */
  87   int op,             /* One of TK_INSERT, TK_UPDATE, TK_DELETE */
  88   IdList *pColumns,   /* column list if this is an UPDATE OF trigger */
  89   SrcList *pTableName,/* The name of the table/view the trigger applies to */
  90   Expr *pWhen,        /* WHEN clause */
  91   int isTemp,         /* True if the TEMPORARY keyword is present */
  92   int noErr           /* Suppress errors if the trigger already exists */
  93 ){
  94   Trigger *pTrigger = 0;  /* The new trigger */
  95   Table *pTab;            /* Table that the trigger fires off of */
  96   char *zName = 0;        /* Name of the trigger */
  97   sqlite3 *db = pParse->db;  /* The database connection */
  98   int iDb;                /* The database to store the trigger in */
  99   Token *pName;           /* The unqualified db name */
 100   DbFixer sFix;           /* State vector for the DB fixer */
 101
 102   assert( pName1!=0 );   /* pName1->z might be NULL, but not pName1 itself */
 103   assert( pName2!=0 );
 104   assert( op==TK_INSERT || op==TK_UPDATE || op==TK_DELETE );
 105   assert( op>0 && op<0xff );
 106   if( isTemp ){
 107     /* If TEMP was specified, then the trigger name may not be qualified. */
 108     if( pName2->n>0 ){
 109       sqlite3ErrorMsg(pParse, "temporary trigger may not have qualified name");
 110       goto trigger_cleanup;
 111     }
 112     iDb = 1;
 113     pName = pName1;
 114   }else{
 115     /* Figure out the db that the trigger will be created in */
 116     iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pName);
 117     if( iDb<0 ){
 118       goto trigger_cleanup;
 119     }
 120   }
 121   if( !pTableName || db->mallocFailed ){
 122     goto trigger_cleanup;
 123   }
 124
 125   /* A long-standing parser bug is that this syntax was allowed:
 126   **
 127   **    CREATE TRIGGER attached.demo AFTER INSERT ON attached.tab ....
 128   **                                                 ^^^^^^^^
 129   **
 130   ** To maintain backwards compatibility, ignore the database
 131   ** name on pTableName if we are reparsing out of SQLITE_MASTER.
 132   */
 133   if( db->init.busy && iDb!=1 ){
 134     sqlite3DbFree(db, pTableName->a[0].zDatabase);
 135     pTableName->a[0].zDatabase = 0;
 136   }
 137
 138   /* If the trigger name was unqualified, and the table is a temp table,
 139   ** then set iDb to 1 to create the trigger in the temporary database.
 140   ** If sqlite3SrcListLookup() returns 0, indicating the table does not
 141   ** exist, the error is caught by the block below.
 142   */
 143   pTab = sqlite3SrcListLookup(pParse, pTableName);
 144   if( db->init.busy==0 && pName2->n==0 && pTab
 145         && pTab->pSchema==db->aDb[1].pSchema ){
 146     iDb = 1;
 147   }
 148
 149   /* Ensure the table name matches database name and that the table exists */
 150   if( db->mallocFailed ) goto trigger_cleanup;
 151   assert( pTableName->nSrc==1 );
 152   sqlite3FixInit(&sFix, pParse, iDb, "trigger", pName);
 153   if( sqlite3FixSrcList(&sFix, pTableName) ){
 154     goto trigger_cleanup;
 155   }
 156   pTab = sqlite3SrcListLookup(pParse, pTableName);
 157   if( !pTab ){
 158     /* The table does not exist. */
 159     if( db->init.iDb==1 ){
 160       /* Ticket #3810.
 161       ** Normally, whenever a table is dropped, all associated triggers are
 162       ** dropped too.  But if a TEMP trigger is created on a non-TEMP table
 163       ** and the table is dropped by a different database connection, the
 164       ** trigger is not visible to the database connection that does the
 165       ** drop so the trigger cannot be dropped.  This results in an
 166       ** "orphaned trigger" - a trigger whose associated table is missing.
 167       */
 168       db->init.orphanTrigger = 1;
 169     }
 170     goto trigger_cleanup;
 171   }
 172   if( IsVirtual(pTab) ){
 173     sqlite3ErrorMsg(pParse, "cannot create triggers on virtual tables");
 174     goto trigger_cleanup;
 175   }
 176
 177   /* Check that the trigger name is not reserved and that no trigger of the
 178   ** specified name exists */
 179   zName = sqlite3NameFromToken(db, pName);
 180   if( !zName || SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
 181     goto trigger_cleanup;
 182   }
 183   assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
 184   if( !IN_RENAME_OBJECT ){
 185     if( sqlite3HashFind(&(db->aDb[iDb].pSchema->trigHash),zName) ){
 186       if( !noErr ){
 187         sqlite3ErrorMsg(pParse, "trigger %T already exists", pName);
 188       }else{
 189         assert( !db->init.busy );
 190         sqlite3CodeVerifySchema(pParse, iDb);
 191       }
 192       goto trigger_cleanup;
 193     }
 194   }
 195
 196   /* Do not create a trigger on a system table */
 197   if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 ){
 198     sqlite3ErrorMsg(pParse, "cannot create trigger on system table");
 199     goto trigger_cleanup;
 200   }
 201
 202   /* INSTEAD of triggers are only for views and views only support INSTEAD
 203   ** of triggers.
 204   */
 205   if( pTab->pSelect && tr_tm!=TK_INSTEAD ){
 206     sqlite3ErrorMsg(pParse, "cannot create %s trigger on view: %S",
 207         (tr_tm == TK_BEFORE)?"BEFORE":"AFTER", pTableName, 0);
 208     goto trigger_cleanup;
 209   }
 210   if( !pTab->pSelect && tr_tm==TK_INSTEAD ){
 211     sqlite3ErrorMsg(pParse, "cannot create INSTEAD OF"
 212         " trigger on table: %S", pTableName, 0);
 213     goto trigger_cleanup;
 214   }
 215
 216 #ifndef SQLITE_OMIT_AUTHORIZATION
 217   if( !IN_RENAME_OBJECT ){
 218     int iTabDb = sqlite3SchemaToIndex(db, pTab->pSchema);
 219     int code = SQLITE_CREATE_TRIGGER;
 220     const char *zDb = db->aDb[iTabDb].zDbSName;
 221     const char *zDbTrig = isTemp ? db->aDb[1].zDbSName : zDb;
 222     if( iTabDb==1 || isTemp ) code = SQLITE_CREATE_TEMP_TRIGGER;
 223     if( sqlite3AuthCheck(pParse, code, zName, pTab->zName, zDbTrig) ){
 224       goto trigger_cleanup;
 225     }
 226     if( sqlite3AuthCheck(pParse, SQLITE_INSERT, SCHEMA_TABLE(iTabDb),0,zDb)){
 227       goto trigger_cleanup;
 228     }
 229   }
 230 #endif
 231
 232   /* INSTEAD OF triggers can only appear on views and BEFORE triggers
 233   ** cannot appear on views.  So we might as well translate every
 234   ** INSTEAD OF trigger into a BEFORE trigger.  It simplifies code
 235   ** elsewhere.
 236   */
 237   if (tr_tm == TK_INSTEAD){
 238     tr_tm = TK_BEFORE;
 239   }
 240
 241   /* Build the Trigger object */
 242   pTrigger = (Trigger*)sqlite3DbMallocZero(db, sizeof(Trigger));
 243   if( pTrigger==0 ) goto trigger_cleanup;
 244   pTrigger->zName = zName;
 245   zName = 0;
 246   pTrigger->table = sqlite3DbStrDup(db, pTableName->a[0].zName);
 247   pTrigger->pSchema = db->aDb[iDb].pSchema;
 248   pTrigger->pTabSchema = pTab->pSchema;
 249   pTrigger->op = (u8)op;
 250   pTrigger->tr_tm = tr_tm==TK_BEFORE ? TRIGGER_BEFORE : TRIGGER_AFTER;
 251   if( IN_RENAME_OBJECT ){
 252     sqlite3RenameTokenRemap(pParse, pTrigger->table, pTableName->a[0].zName);
 253     pTrigger->pWhen = pWhen;
 254     pWhen = 0;
 255   }else{
 256     pTrigger->pWhen = sqlite3ExprDup(db, pWhen, EXPRDUP_REDUCE);
 257   }
 258   pTrigger->pColumns = pColumns;
 259   pColumns = 0;
 260   assert( pParse->pNewTrigger==0 );
 261   pParse->pNewTrigger = pTrigger;
 262
 263 trigger_cleanup:
 264   sqlite3DbFree(db, zName);
 265   sqlite3SrcListDelete(db, pTableName);
 266   sqlite3IdListDelete(db, pColumns);
 267   sqlite3ExprDelete(db, pWhen);
 268   if( !pParse->pNewTrigger ){
 269     sqlite3DeleteTrigger(db, pTrigger);
 270   }else{
 271     assert( pParse->pNewTrigger==pTrigger );
 272   }
 273 }
 274
 275 /*
 276 ** This routine is called after all of the trigger actions have been parsed
 277 ** in order to complete the process of building the trigger.
 278 */
 279 void sqlite3FinishTrigger(
 280   Parse *pParse,          /* Parser context */
 281   TriggerStep *pStepList, /* The triggered program */
 282   Token *pAll             /* Token that describes the complete CREATE TRIGGER */
 283 ){
 284   Trigger *pTrig = pParse->pNewTrigger;   /* Trigger being finished */
 285   char *zName;                            /* Name of trigger */
 286   sqlite3 *db = pParse->db;               /* The database */
 287   DbFixer sFix;                           /* Fixer object */
 288   int iDb;                                /* Database containing the trigger */
 289   Token nameToken;                        /* Trigger name for error reporting */
 290
 291   pParse->pNewTrigger = 0;
 292   if( NEVER(pParse->nErr) || !pTrig ) goto triggerfinish_cleanup;
 293   zName = pTrig->zName;
 294   iDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema);
 295   pTrig->step_list = pStepList;
 296   while( pStepList ){
 297     pStepList->pTrig = pTrig;
 298     pStepList = pStepList->pNext;
 299   }
 300   sqlite3TokenInit(&nameToken, pTrig->zName);
 301   sqlite3FixInit(&sFix, pParse, iDb, "trigger", &nameToken);
 302   if( sqlite3FixTriggerStep(&sFix, pTrig->step_list)
 303    || sqlite3FixExpr(&sFix, pTrig->pWhen)
 304   ){
 305     goto triggerfinish_cleanup;
 306   }
 307
 308 #ifndef SQLITE_OMIT_ALTERTABLE
 309   if( IN_RENAME_OBJECT ){
 310     assert( !db->init.busy );
 311     pParse->pNewTrigger = pTrig;
 312     pTrig = 0;
 313   }else
 314 #endif
 315
 316   /* if we are not initializing,
 317   ** build the sqlite_master entry
 318   */
 319   if( !db->init.busy ){
 320     Vdbe *v;
 321     char *z;
 322
 323     /* Make an entry in the sqlite_master table */
 324     v = sqlite3GetVdbe(pParse);
 325     if( v==0 ) goto triggerfinish_cleanup;
 326     sqlite3BeginWriteOperation(pParse, 0, iDb);
 327     z = sqlite3DbStrNDup(db, (char*)pAll->z, pAll->n);
 328     testcase( z==0 );
 329     sqlite3NestedParse(pParse,
 330        "INSERT INTO %Q.%s VALUES('trigger',%Q,%Q,0,'CREATE TRIGGER %q')",
 331        db->aDb[iDb].zDbSName, MASTER_NAME, zName,
 332        pTrig->table, z);
 333     sqlite3DbFree(db, z);
 334     sqlite3ChangeCookie(pParse, iDb);
 335     sqlite3VdbeAddParseSchemaOp(v, iDb,
 336         sqlite3MPrintf(db, "type='trigger' AND name='%q'", zName));
 337   }
 338
 339   if( db->init.busy ){
 340     Trigger *pLink = pTrig;
 341     Hash *pHash = &db->aDb[iDb].pSchema->trigHash;
 342     assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
 343     pTrig = sqlite3HashInsert(pHash, zName, pTrig);
 344     if( pTrig ){
 345       sqlite3OomFault(db);
 346     }else if( pLink->pSchema==pLink->pTabSchema ){
 347       Table *pTab;
 348       pTab = sqlite3HashFind(&pLink->pTabSchema->tblHash, pLink->table);
 349       assert( pTab!=0 );
 350       pLink->pNext = pTab->pTrigger;
 351       pTab->pTrigger = pLink;
 352     }
 353   }
 354
 355 triggerfinish_cleanup:
 356   sqlite3DeleteTrigger(db, pTrig);
 357   assert( IN_RENAME_OBJECT || !pParse->pNewTrigger );
 358   sqlite3DeleteTriggerStep(db, pStepList);
 359 }
 360
 361 /*
 362 ** Duplicate a range of text from an SQL statement, then convert all
 363 ** whitespace characters into ordinary space characters.
 364 */
 365 static char *triggerSpanDup(sqlite3 *db, const char *zStart, const char *zEnd){
 366   char *z = sqlite3DbSpanDup(db, zStart, zEnd);
 367   int i;
 368   if( z ) for(i=0; z[i]; i++) if( sqlite3Isspace(z[i]) ) z[i] = ' ';
 369   return z;
 370 }
 371
 372 /*
 373 ** Turn a SELECT statement (that the pSelect parameter points to) into
 374 ** a trigger step.  Return a pointer to a TriggerStep structure.
 375 **
 376 ** The parser calls this routine when it finds a SELECT statement in
 377 ** body of a TRIGGER.
 378 */
 379 TriggerStep *sqlite3TriggerSelectStep(
 380   sqlite3 *db,                /* Database connection */
 381   Select *pSelect,            /* The SELECT statement */
 382   const char *zStart,         /* Start of SQL text */
 383   const char *zEnd            /* End of SQL text */
 384 ){
 385   TriggerStep *pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep));
 386   if( pTriggerStep==0 ) {
 387     sqlite3SelectDelete(db, pSelect);
 388     return 0;
 389   }
 390   pTriggerStep->op = TK_SELECT;
 391   pTriggerStep->pSelect = pSelect;
 392   pTriggerStep->orconf = OE_Default;
 393   pTriggerStep->zSpan = triggerSpanDup(db, zStart, zEnd);
 394   return pTriggerStep;
 395 }
 396
 397 /*
 398 ** Allocate space to hold a new trigger step.  The allocated space
 399 ** holds both the TriggerStep object and the TriggerStep.target.z string.
 400 **
 401 ** If an OOM error occurs, NULL is returned and db->mallocFailed is set.
 402 */
 403 static TriggerStep *triggerStepAllocate(
 404   Parse *pParse,              /* Parser context */
 405   u8 op,                      /* Trigger opcode */
 406   Token *pName,               /* The target name */
 407   const char *zStart,         /* Start of SQL text */
 408   const char *zEnd            /* End of SQL text */
 409 ){
 410   sqlite3 *db = pParse->db;
 411   TriggerStep *pTriggerStep;
 412
 413   pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep) + pName->n + 1);
 414   if( pTriggerStep ){
 415     char *z = (char*)&pTriggerStep[1];
 416     memcpy(z, pName->z, pName->n);
 417     sqlite3Dequote(z);
 418     pTriggerStep->zTarget = z;
 419     pTriggerStep->op = op;
 420     pTriggerStep->zSpan = triggerSpanDup(db, zStart, zEnd);
 421     if( IN_RENAME_OBJECT ){
 422       sqlite3RenameTokenMap(pParse, pTriggerStep->zTarget, pName);
 423     }
 424   }
 425   return pTriggerStep;
 426 }
 427
 428 /*
 429 ** Build a trigger step out of an INSERT statement.  Return a pointer
 430 ** to the new trigger step.
 431 **
 432 ** The parser calls this routine when it sees an INSERT inside the
 433 ** body of a trigger.
 434 */
 435 TriggerStep *sqlite3TriggerInsertStep(
 436   Parse *pParse,      /* Parser */
 437   Token *pTableName,  /* Name of the table into which we insert */
 438   IdList *pColumn,    /* List of columns in pTableName to insert into */
 439   Select *pSelect,    /* A SELECT statement that supplies values */
 440   u8 orconf,          /* The conflict algorithm (OE_Abort, OE_Replace, etc.) */
 441   Upsert *pUpsert,    /* ON CONFLICT clauses for upsert */
 442   const char *zStart, /* Start of SQL text */
 443   const char *zEnd    /* End of SQL text */
 444 ){
 445   sqlite3 *db = pParse->db;
 446   TriggerStep *pTriggerStep;
 447
 448   assert(pSelect != 0 || db->mallocFailed);
 449
 450   pTriggerStep = triggerStepAllocate(pParse, TK_INSERT, pTableName,zStart,zEnd);
 451   if( pTriggerStep ){
 452     if( IN_RENAME_OBJECT ){
 453       pTriggerStep->pSelect = pSelect;
 454       pSelect = 0;
 455     }else{
 456       pTriggerStep->pSelect = sqlite3SelectDup(db, pSelect, EXPRDUP_REDUCE);
 457     }
 458     pTriggerStep->pIdList = pColumn;
 459     pTriggerStep->pUpsert = pUpsert;
 460     pTriggerStep->orconf = orconf;
 461   }else{
 462     testcase( pColumn );
 463     sqlite3IdListDelete(db, pColumn);
 464     testcase( pUpsert );
 465     sqlite3UpsertDelete(db, pUpsert);
 466   }
 467   sqlite3SelectDelete(db, pSelect);
 468
 469   return pTriggerStep;
 470 }
 471
 472 /*
 473 ** Construct a trigger step that implements an UPDATE statement and return
 474 ** a pointer to that trigger step.  The parser calls this routine when it
 475 ** sees an UPDATE statement inside the body of a CREATE TRIGGER.
 476 */
 477 TriggerStep *sqlite3TriggerUpdateStep(
 478   Parse *pParse,          /* Parser */
 479   Token *pTableName,   /* Name of the table to be updated */
 480   ExprList *pEList,    /* The SET clause: list of column and new values */
 481   Expr *pWhere,        /* The WHERE clause */
 482   u8 orconf,           /* The conflict algorithm. (OE_Abort, OE_Ignore, etc) */
 483   const char *zStart,  /* Start of SQL text */
 484   const char *zEnd     /* End of SQL text */
 485 ){
 486   sqlite3 *db = pParse->db;
 487   TriggerStep *pTriggerStep;
 488
 489   pTriggerStep = triggerStepAllocate(pParse, TK_UPDATE, pTableName,zStart,zEnd);
 490   if( pTriggerStep ){
 491     if( IN_RENAME_OBJECT ){
 492       pTriggerStep->pExprList = pEList;
 493       pTriggerStep->pWhere = pWhere;
 494       pEList = 0;
 495       pWhere = 0;
 496     }else{
 497       pTriggerStep->pExprList = sqlite3ExprListDup(db, pEList, EXPRDUP_REDUCE);
 498       pTriggerStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
 499     }
 500     pTriggerStep->orconf = orconf;
 501   }
 502   sqlite3ExprListDelete(db, pEList);
 503   sqlite3ExprDelete(db, pWhere);
 504   return pTriggerStep;
 505 }
 506
 507 /*
 508 ** Construct a trigger step that implements a DELETE statement and return
 509 ** a pointer to that trigger step.  The parser calls this routine when it
 510 ** sees a DELETE statement inside the body of a CREATE TRIGGER.
 511 */
 512 TriggerStep *sqlite3TriggerDeleteStep(
 513   Parse *pParse,          /* Parser */
 514   Token *pTableName,      /* The table from which rows are deleted */
 515   Expr *pWhere,           /* The WHERE clause */
 516   const char *zStart,     /* Start of SQL text */
 517   const char *zEnd        /* End of SQL text */
 518 ){
 519   sqlite3 *db = pParse->db;
 520   TriggerStep *pTriggerStep;
 521
 522   pTriggerStep = triggerStepAllocate(pParse, TK_DELETE, pTableName,zStart,zEnd);
 523   if( pTriggerStep ){
 524     if( IN_RENAME_OBJECT ){
 525       pTriggerStep->pWhere = pWhere;
 526       pWhere = 0;
 527     }else{
 528       pTriggerStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
 529     }
 530     pTriggerStep->orconf = OE_Default;
 531   }
 532   sqlite3ExprDelete(db, pWhere);
 533   return pTriggerStep;
 534 }
 535
 536 /*
 537 ** Recursively delete a Trigger structure
 538 */
 539 void sqlite3DeleteTrigger(sqlite3 *db, Trigger *pTrigger){
 540   if( pTrigger==0 ) return;
 541   sqlite3DeleteTriggerStep(db, pTrigger->step_list);
 542   sqlite3DbFree(db, pTrigger->zName);
 543   sqlite3DbFree(db, pTrigger->table);
 544   sqlite3ExprDelete(db, pTrigger->pWhen);
 545   sqlite3IdListDelete(db, pTrigger->pColumns);
 546   sqlite3DbFree(db, pTrigger);
 547 }
 548
 549 /*
 550 ** This function is called to drop a trigger from the database schema.
 551 **
 552 ** This may be called directly from the parser and therefore identifies
 553 ** the trigger by name.  The sqlite3DropTriggerPtr() routine does the
 554 ** same job as this routine except it takes a pointer to the trigger
 555 ** instead of the trigger name.
 556 **/
 557 void sqlite3DropTrigger(Parse *pParse, SrcList *pName, int noErr){
 558   Trigger *pTrigger = 0;
 559   int i;
 560   const char *zDb;
 561   const char *zName;
 562   sqlite3 *db = pParse->db;
 563
 564   if( db->mallocFailed ) goto drop_trigger_cleanup;
 565   if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
 566     goto drop_trigger_cleanup;
 567   }
 568
 569   assert( pName->nSrc==1 );
 570   zDb = pName->a[0].zDatabase;
 571   zName = pName->a[0].zName;
 572   assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
 573   for(i=OMIT_TEMPDB; i<db->nDb; i++){
 574     int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
 575     if( zDb && sqlite3StrICmp(db->aDb[j].zDbSName, zDb) ) continue;
 576     assert( sqlite3SchemaMutexHeld(db, j, 0) );
 577     pTrigger = sqlite3HashFind(&(db->aDb[j].pSchema->trigHash), zName);
 578     if( pTrigger ) break;
 579   }
 580   if( !pTrigger ){
 581     if( !noErr ){
 582       sqlite3ErrorMsg(pParse, "no such trigger: %S", pName, 0);
 583     }else{
 584       sqlite3CodeVerifyNamedSchema(pParse, zDb);
 585     }
 586     pParse->checkSchema = 1;
 587     goto drop_trigger_cleanup;
 588   }
 589   sqlite3DropTriggerPtr(pParse, pTrigger);
 590
 591 drop_trigger_cleanup:
 592   sqlite3SrcListDelete(db, pName);
 593 }
 594
 595 /*
 596 ** Return a pointer to the Table structure for the table that a trigger
 597 ** is set on.
 598 */
 599 static Table *tableOfTrigger(Trigger *pTrigger){
 600   return sqlite3HashFind(&pTrigger->pTabSchema->tblHash, pTrigger->table);
 601 }
 602
 603
 604 /*
 605 ** Drop a trigger given a pointer to that trigger.
 606 */
 607 void sqlite3DropTriggerPtr(Parse *pParse, Trigger *pTrigger){
 608   Table   *pTable;
 609   Vdbe *v;
 610   sqlite3 *db = pParse->db;
 611   int iDb;
 612
 613   iDb = sqlite3SchemaToIndex(pParse->db, pTrigger->pSchema);
 614   assert( iDb>=0 && iDb<db->nDb );
 615   pTable = tableOfTrigger(pTrigger);
 616   assert( pTable );
 617   assert( pTable->pSchema==pTrigger->pSchema || iDb==1 );
 618 #ifndef SQLITE_OMIT_AUTHORIZATION
 619   {
 620     int code = SQLITE_DROP_TRIGGER;
 621     const char *zDb = db->aDb[iDb].zDbSName;
 622     const char *zTab = SCHEMA_TABLE(iDb);
 623     if( iDb==1 ) code = SQLITE_DROP_TEMP_TRIGGER;
 624     if( sqlite3AuthCheck(pParse, code, pTrigger->zName, pTable->zName, zDb) ||
 625       sqlite3AuthCheck(pParse, SQLITE_DELETE, zTab, 0, zDb) ){
 626       return;
 627     }
 628   }
 629 #endif
 630
 631   /* Generate code to destroy the database record of the trigger.
 632   */
 633   assert( pTable!=0 );
 634   if( (v = sqlite3GetVdbe(pParse))!=0 ){
 635     sqlite3NestedParse(pParse,
 636        "DELETE FROM %Q.%s WHERE name=%Q AND type='trigger'",
 637        db->aDb[iDb].zDbSName, MASTER_NAME, pTrigger->zName
 638     );
 639     sqlite3ChangeCookie(pParse, iDb);
 640     sqlite3VdbeAddOp4(v, OP_DropTrigger, iDb, 0, 0, pTrigger->zName, 0);
 641   }
 642 }
 643
 644 /*
 645 ** Remove a trigger from the hash tables of the sqlite* pointer.
 646 */
 647 void sqlite3UnlinkAndDeleteTrigger(sqlite3 *db, int iDb, const char *zName){
 648   Trigger *pTrigger;
 649   Hash *pHash;
 650
 651   assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
 652   pHash = &(db->aDb[iDb].pSchema->trigHash);
 653   pTrigger = sqlite3HashInsert(pHash, zName, 0);
 654   if( ALWAYS(pTrigger) ){
 655     if( pTrigger->pSchema==pTrigger->pTabSchema ){
 656       Table *pTab = tableOfTrigger(pTrigger);
 657       Trigger **pp;
 658       for(pp=&pTab->pTrigger; *pp!=pTrigger; pp=&((*pp)->pNext));
 659       *pp = (*pp)->pNext;
 660     }
 661     sqlite3DeleteTrigger(db, pTrigger);
 662     db->mDbFlags |= DBFLAG_SchemaChange;
 663   }
 664 }
 665
 666 /*
 667 ** pEList is the SET clause of an UPDATE statement.  Each entry
 668 ** in pEList is of the format <id>=<expr>.  If any of the entries
 669 ** in pEList have an <id> which matches an identifier in pIdList,
 670 ** then return TRUE.  If pIdList==NULL, then it is considered a
 671 ** wildcard that matches anything.  Likewise if pEList==NULL then
 672 ** it matches anything so always return true.  Return false only
 673 ** if there is no match.
 674 */
 675 static int checkColumnOverlap(IdList *pIdList, ExprList *pEList){
 676   int e;
 677   if( pIdList==0 || NEVER(pEList==0) ) return 1;
 678   for(e=0; e<pEList->nExpr; e++){
 679     if( sqlite3IdListIndex(pIdList, pEList->a[e].zName)>=0 ) return 1;
 680   }
 681   return 0;
 682 }
 683
 684 /*
 685 ** Return a list of all triggers on table pTab if there exists at least
 686 ** one trigger that must be fired when an operation of type 'op' is
 687 ** performed on the table, and, if that operation is an UPDATE, if at
 688 ** least one of the columns in pChanges is being modified.
 689 */
 690 Trigger *sqlite3TriggersExist(
 691   Parse *pParse,          /* Parse context */
 692   Table *pTab,            /* The table the contains the triggers */
 693   int op,                 /* one of TK_DELETE, TK_INSERT, TK_UPDATE */
 694   ExprList *pChanges,     /* Columns that change in an UPDATE statement */
 695   int *pMask              /* OUT: Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
 696 ){
 697   int mask = 0;
 698   Trigger *pList = 0;
 699   Trigger *p;
 700
 701   if( (pParse->db->flags & SQLITE_EnableTrigger)!=0 ){
 702     pList = sqlite3TriggerList(pParse, pTab);
 703   }
 704   assert( pList==0 || IsVirtual(pTab)==0 );
 705   for(p=pList; p; p=p->pNext){
 706     if( p->op==op && checkColumnOverlap(p->pColumns, pChanges) ){
 707       mask |= p->tr_tm;
 708     }
 709   }
 710   if( pMask ){
 711     *pMask = mask;
 712   }
 713   return (mask ? pList : 0);
 714 }
 715
 716 /*
 717 ** Convert the pStep->zTarget string into a SrcList and return a pointer
 718 ** to that SrcList.
 719 **
 720 ** This routine adds a specific database name, if needed, to the target when
 721 ** forming the SrcList.  This prevents a trigger in one database from
 722 ** referring to a target in another database.  An exception is when the
 723 ** trigger is in TEMP in which case it can refer to any other database it
 724 ** wants.
 725 */
 726 static SrcList *targetSrcList(
 727   Parse *pParse,       /* The parsing context */
 728   TriggerStep *pStep   /* The trigger containing the target token */
 729 ){
 730   sqlite3 *db = pParse->db;
 731   int iDb;             /* Index of the database to use */
 732   SrcList *pSrc;       /* SrcList to be returned */
 733
 734   pSrc = sqlite3SrcListAppend(pParse, 0, 0, 0);
 735   if( pSrc ){
 736     assert( pSrc->nSrc>0 );
 737     pSrc->a[pSrc->nSrc-1].zName = sqlite3DbStrDup(db, pStep->zTarget);
 738     iDb = sqlite3SchemaToIndex(db, pStep->pTrig->pSchema);
 739     if( iDb==0 || iDb>=2 ){
 740       const char *zDb;
 741       assert( iDb<db->nDb );
 742       zDb = db->aDb[iDb].zDbSName;
 743       pSrc->a[pSrc->nSrc-1].zDatabase =  sqlite3DbStrDup(db, zDb);
 744     }
 745   }
 746   return pSrc;
 747 }
 748
 749 /*
 750 ** Generate VDBE code for the statements inside the body of a single
 751 ** trigger.
 752 */
 753 static int codeTriggerProgram(
 754   Parse *pParse,            /* The parser context */
 755   TriggerStep *pStepList,   /* List of statements inside the trigger body */
 756   int orconf                /* Conflict algorithm. (OE_Abort, etc) */
 757 ){
 758   TriggerStep *pStep;
 759   Vdbe *v = pParse->pVdbe;
 760   sqlite3 *db = pParse->db;
 761
 762   assert( pParse->pTriggerTab && pParse->pToplevel );
 763   assert( pStepList );
 764   assert( v!=0 );
 765   for(pStep=pStepList; pStep; pStep=pStep->pNext){
 766     /* Figure out the ON CONFLICT policy that will be used for this step
 767     ** of the trigger program. If the statement that caused this trigger
 768     ** to fire had an explicit ON CONFLICT, then use it. Otherwise, use
 769     ** the ON CONFLICT policy that was specified as part of the trigger
 770     ** step statement. Example:
 771     **
 772     **   CREATE TRIGGER AFTER INSERT ON t1 BEGIN;
 773     **     INSERT OR REPLACE INTO t2 VALUES(new.a, new.b);
 774     **   END;
 775     **
 776     **   INSERT INTO t1 ... ;            -- insert into t2 uses REPLACE policy
 777     **   INSERT OR IGNORE INTO t1 ... ;  -- insert into t2 uses IGNORE policy
 778     */
 779     pParse->eOrconf = (orconf==OE_Default)?pStep->orconf:(u8)orconf;
 780     assert( pParse->okConstFactor==0 );
 781
 782 #ifndef SQLITE_OMIT_TRACE
 783     if( pStep->zSpan ){
 784       sqlite3VdbeAddOp4(v, OP_Trace, 0x7fffffff, 1, 0,
 785                         sqlite3MPrintf(db, "-- %s", pStep->zSpan),
 786                         P4_DYNAMIC);
 787     }
 788 #endif
 789
 790     switch( pStep->op ){
 791       case TK_UPDATE: {
 792         sqlite3Update(pParse,
 793           targetSrcList(pParse, pStep),
 794           sqlite3ExprListDup(db, pStep->pExprList, 0),
 795           sqlite3ExprDup(db, pStep->pWhere, 0),
 796           pParse->eOrconf, 0, 0, 0
 797         );
 798         break;
 799       }
 800       case TK_INSERT: {
 801         sqlite3Insert(pParse,
 802           targetSrcList(pParse, pStep),
 803           sqlite3SelectDup(db, pStep->pSelect, 0),
 804           sqlite3IdListDup(db, pStep->pIdList),
 805           pParse->eOrconf,
 806           sqlite3UpsertDup(db, pStep->pUpsert)
 807         );
 808         break;
 809       }
 810       case TK_DELETE: {
 811         sqlite3DeleteFrom(pParse,
 812           targetSrcList(pParse, pStep),
 813           sqlite3ExprDup(db, pStep->pWhere, 0), 0, 0
 814         );
 815         break;
 816       }
 817       default: assert( pStep->op==TK_SELECT ); {
 818         SelectDest sDest;
 819         Select *pSelect = sqlite3SelectDup(db, pStep->pSelect, 0);
 820         sqlite3SelectDestInit(&sDest, SRT_Discard, 0);
 821         sqlite3Select(pParse, pSelect, &sDest);
 822         sqlite3SelectDelete(db, pSelect);
 823         break;
 824       }
 825     }
 826     if( pStep->op!=TK_SELECT ){
 827       sqlite3VdbeAddOp0(v, OP_ResetCount);
 828     }
 829   }
 830
 831   return 0;
 832 }
 833
 834 #ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
 835 /*
 836 ** This function is used to add VdbeComment() annotations to a VDBE
 837 ** program. It is not used in production code, only for debugging.
 838 */
 839 static const char *onErrorText(int onError){
 840   switch( onError ){
 841     case OE_Abort:    return "abort";
 842     case OE_Rollback: return "rollback";
 843     case OE_Fail:     return "fail";
 844     case OE_Replace:  return "replace";
 845     case OE_Ignore:   return "ignore";
 846     case OE_Default:  return "default";
 847   }
 848   return "n/a";
 849 }
 850 #endif
 851
 852 /*
 853 ** Parse context structure pFrom has just been used to create a sub-vdbe
 854 ** (trigger program). If an error has occurred, transfer error information
 855 ** from pFrom to pTo.
 856 */
 857 static void transferParseError(Parse *pTo, Parse *pFrom){
 858   assert( pFrom->zErrMsg==0 || pFrom->nErr );
 859   assert( pTo->zErrMsg==0 || pTo->nErr );
 860   if( pTo->nErr==0 ){
 861     pTo->zErrMsg = pFrom->zErrMsg;
 862     pTo->nErr = pFrom->nErr;
 863     pTo->rc = pFrom->rc;
 864   }else{
 865     sqlite3DbFree(pFrom->db, pFrom->zErrMsg);
 866   }
 867 }
 868
 869 /*
 870 ** Create and populate a new TriggerPrg object with a sub-program
 871 ** implementing trigger pTrigger with ON CONFLICT policy orconf.
 872 */
 873 static TriggerPrg *codeRowTrigger(
 874   Parse *pParse,       /* Current parse context */
 875   Trigger *pTrigger,   /* Trigger to code */
 876   Table *pTab,         /* The table pTrigger is attached to */
 877   int orconf           /* ON CONFLICT policy to code trigger program with */
 878 ){
 879   Parse *pTop = sqlite3ParseToplevel(pParse);
 880   sqlite3 *db = pParse->db;   /* Database handle */
 881   TriggerPrg *pPrg;           /* Value to return */
 882   Expr *pWhen = 0;            /* Duplicate of trigger WHEN expression */
 883   Vdbe *v;                    /* Temporary VM */
 884   NameContext sNC;            /* Name context for sub-vdbe */
 885   SubProgram *pProgram = 0;   /* Sub-vdbe for trigger program */
 886   Parse *pSubParse;           /* Parse context for sub-vdbe */
 887   int iEndTrigger = 0;        /* Label to jump to if WHEN is false */
 888
 889   assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
 890   assert( pTop->pVdbe );
 891
 892   /* Allocate the TriggerPrg and SubProgram objects. To ensure that they
 893   ** are freed if an error occurs, link them into the Parse.pTriggerPrg
 894   ** list of the top-level Parse object sooner rather than later.  */
 895   pPrg = sqlite3DbMallocZero(db, sizeof(TriggerPrg));
 896   if( !pPrg ) return 0;
 897   pPrg->pNext = pTop->pTriggerPrg;
 898   pTop->pTriggerPrg = pPrg;
 899   pPrg->pProgram = pProgram = sqlite3DbMallocZero(db, sizeof(SubProgram));
 900   if( !pProgram ) return 0;
 901   sqlite3VdbeLinkSubProgram(pTop->pVdbe, pProgram);
 902   pPrg->pTrigger = pTrigger;
 903   pPrg->orconf = orconf;
 904   pPrg->aColmask[0] = 0xffffffff;
 905   pPrg->aColmask[1] = 0xffffffff;
 906
 907   /* Allocate and populate a new Parse context to use for coding the
 908   ** trigger sub-program.  */
 909   pSubParse = sqlite3StackAllocZero(db, sizeof(Parse));
 910   if( !pSubParse ) return 0;
 911   memset(&sNC, 0, sizeof(sNC));
 912   sNC.pParse = pSubParse;
 913   pSubParse->db = db;
 914   pSubParse->pTriggerTab = pTab;
 915   pSubParse->pToplevel = pTop;
 916   pSubParse->zAuthContext = pTrigger->zName;
 917   pSubParse->eTriggerOp = pTrigger->op;
 918   pSubParse->nQueryLoop = pParse->nQueryLoop;
 919   pSubParse->disableVtab = pParse->disableVtab;
 920
 921   v = sqlite3GetVdbe(pSubParse);
 922   if( v ){
 923     VdbeComment((v, "Start: %s.%s (%s %s%s%s ON %s)",
 924       pTrigger->zName, onErrorText(orconf),
 925       (pTrigger->tr_tm==TRIGGER_BEFORE ? "BEFORE" : "AFTER"),
 926         (pTrigger->op==TK_UPDATE ? "UPDATE" : ""),
 927         (pTrigger->op==TK_INSERT ? "INSERT" : ""),
 928         (pTrigger->op==TK_DELETE ? "DELETE" : ""),
 929       pTab->zName
 930     ));
 931 #ifndef SQLITE_OMIT_TRACE
 932     if( pTrigger->zName ){
 933       sqlite3VdbeChangeP4(v, -1,
 934         sqlite3MPrintf(db, "-- TRIGGER %s", pTrigger->zName), P4_DYNAMIC
 935       );
 936     }
 937 #endif
 938
 939     /* If one was specified, code the WHEN clause. If it evaluates to false
 940     ** (or NULL) the sub-vdbe is immediately halted by jumping to the
 941     ** OP_Halt inserted at the end of the program.  */
 942     if( pTrigger->pWhen ){
 943       pWhen = sqlite3ExprDup(db, pTrigger->pWhen, 0);
 944       if( SQLITE_OK==sqlite3ResolveExprNames(&sNC, pWhen)
 945        && db->mallocFailed==0
 946       ){
 947         iEndTrigger = sqlite3VdbeMakeLabel(pSubParse);
 948         sqlite3ExprIfFalse(pSubParse, pWhen, iEndTrigger, SQLITE_JUMPIFNULL);
 949       }
 950       sqlite3ExprDelete(db, pWhen);
 951     }
 952
 953     /* Code the trigger program into the sub-vdbe. */
 954     codeTriggerProgram(pSubParse, pTrigger->step_list, orconf);
 955
 956     /* Insert an OP_Halt at the end of the sub-program. */
 957     if( iEndTrigger ){
 958       sqlite3VdbeResolveLabel(v, iEndTrigger);
 959     }
 960     sqlite3VdbeAddOp0(v, OP_Halt);
 961     VdbeComment((v, "End: %s.%s", pTrigger->zName, onErrorText(orconf)));
 962
 963     transferParseError(pParse, pSubParse);
 964     if( db->mallocFailed==0 && pParse->nErr==0 ){
 965       pProgram->aOp = sqlite3VdbeTakeOpArray(v, &pProgram->nOp, &pTop->nMaxArg);
 966     }
 967     pProgram->nMem = pSubParse->nMem;
 968     pProgram->nCsr = pSubParse->nTab;
 969     pProgram->token = (void *)pTrigger;
 970     pPrg->aColmask[0] = pSubParse->oldmask;
 971     pPrg->aColmask[1] = pSubParse->newmask;
 972     sqlite3VdbeDelete(v);
 973   }
 974
 975   assert( !pSubParse->pAinc       && !pSubParse->pZombieTab );
 976   assert( !pSubParse->pTriggerPrg && !pSubParse->nMaxArg );
 977   sqlite3ParserReset(pSubParse);
 978   sqlite3StackFree(db, pSubParse);
 979
 980   return pPrg;
 981 }
 982
 983 /*
 984 ** Return a pointer to a TriggerPrg object containing the sub-program for
 985 ** trigger pTrigger with default ON CONFLICT algorithm orconf. If no such
 986 ** TriggerPrg object exists, a new object is allocated and populated before
 987 ** being returned.
 988 */
 989 static TriggerPrg *getRowTrigger(
 990   Parse *pParse,       /* Current parse context */
 991   Trigger *pTrigger,   /* Trigger to code */
 992   Table *pTab,         /* The table trigger pTrigger is attached to */
 993   int orconf           /* ON CONFLICT algorithm. */
 994 ){
 995   Parse *pRoot = sqlite3ParseToplevel(pParse);
 996   TriggerPrg *pPrg;
 997
 998   assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
 999
1000   /* It may be that this trigger has already been coded (or is in the
1001   ** process of being coded). If this is the case, then an entry with
1002   ** a matching TriggerPrg.pTrigger field will be present somewhere
1003   ** in the Parse.pTriggerPrg list. Search for such an entry.  */
1004   for(pPrg=pRoot->pTriggerPrg;
1005       pPrg && (pPrg->pTrigger!=pTrigger || pPrg->orconf!=orconf);
1006       pPrg=pPrg->pNext
1007   );
1008
1009   /* If an existing TriggerPrg could not be located, create a new one. */
1010   if( !pPrg ){
1011     pPrg = codeRowTrigger(pParse, pTrigger, pTab, orconf);
1012   }
1013
1014   return pPrg;
1015 }
1016
1017 /*
1018 ** Generate code for the trigger program associated with trigger p on
1019 ** table pTab. The reg, orconf and ignoreJump parameters passed to this
1020 ** function are the same as those described in the header function for
1021 ** sqlite3CodeRowTrigger()
1022 */
1023 void sqlite3CodeRowTriggerDirect(
1024   Parse *pParse,       /* Parse context */
1025   Trigger *p,          /* Trigger to code */
1026   Table *pTab,         /* The table to code triggers from */
1027   int reg,             /* Reg array containing OLD.* and NEW.* values */
1028   int orconf,          /* ON CONFLICT policy */
1029   int ignoreJump       /* Instruction to jump to for RAISE(IGNORE) */
1030 ){
1031   Vdbe *v = sqlite3GetVdbe(pParse); /* Main VM */
1032   TriggerPrg *pPrg;
1033   pPrg = getRowTrigger(pParse, p, pTab, orconf);
1034   assert( pPrg || pParse->nErr || pParse->db->mallocFailed );
1035
1036   /* Code the OP_Program opcode in the parent VDBE. P4 of the OP_Program
1037   ** is a pointer to the sub-vdbe containing the trigger program.  */
1038   if( pPrg ){
1039     int bRecursive = (p->zName && 0==(pParse->db->flags&SQLITE_RecTriggers));
1040
1041     sqlite3VdbeAddOp4(v, OP_Program, reg, ignoreJump, ++pParse->nMem,
1042                       (const char *)pPrg->pProgram, P4_SUBPROGRAM);
1043     VdbeComment(
1044         (v, "Call: %s.%s", (p->zName?p->zName:"fkey"), onErrorText(orconf)));
1045
1046     /* Set the P5 operand of the OP_Program instruction to non-zero if
1047     ** recursive invocation of this trigger program is disallowed. Recursive
1048     ** invocation is disallowed if (a) the sub-program is really a trigger,
1049     ** not a foreign key action, and (b) the flag to enable recursive triggers
1050     ** is clear.  */
1051     sqlite3VdbeChangeP5(v, (u8)bRecursive);
1052   }
1053 }
1054
1055 /*
1056 ** This is called to code the required FOR EACH ROW triggers for an operation
1057 ** on table pTab. The operation to code triggers for (INSERT, UPDATE or DELETE)
1058 ** is given by the op parameter. The tr_tm parameter determines whether the
1059 ** BEFORE or AFTER triggers are coded. If the operation is an UPDATE, then
1060 ** parameter pChanges is passed the list of columns being modified.
1061 **
1062 ** If there are no triggers that fire at the specified time for the specified
1063 ** operation on pTab, this function is a no-op.
1064 **
1065 ** The reg argument is the address of the first in an array of registers
1066 ** that contain the values substituted for the new.* and old.* references
1067 ** in the trigger program. If N is the number of columns in table pTab
1068 ** (a copy of pTab->nCol), then registers are populated as follows:
1069 **
1070 **   Register       Contains
1071 **   ------------------------------------------------------
1072 **   reg+0          OLD.rowid
1073 **   reg+1          OLD.* value of left-most column of pTab
1074 **   ...            ...
1075 **   reg+N          OLD.* value of right-most column of pTab
1076 **   reg+N+1        NEW.rowid
1077 **   reg+N+2        OLD.* value of left-most column of pTab
1078 **   ...            ...
1079 **   reg+N+N+1      NEW.* value of right-most column of pTab
1080 **
1081 ** For ON DELETE triggers, the registers containing the NEW.* values will
1082 ** never be accessed by the trigger program, so they are not allocated or
1083 ** populated by the caller (there is no data to populate them with anyway).
1084 ** Similarly, for ON INSERT triggers the values stored in the OLD.* registers
1085 ** are never accessed, and so are not allocated by the caller. So, for an
1086 ** ON INSERT trigger, the value passed to this function as parameter reg
1087 ** is not a readable register, although registers (reg+N) through
1088 ** (reg+N+N+1) are.
1089 **
1090 ** Parameter orconf is the default conflict resolution algorithm for the
1091 ** trigger program to use (REPLACE, IGNORE etc.). Parameter ignoreJump
1092 ** is the instruction that control should jump to if a trigger program
1093 ** raises an IGNORE exception.
1094 */
1095 void sqlite3CodeRowTrigger(
1096   Parse *pParse,       /* Parse context */
1097   Trigger *pTrigger,   /* List of triggers on table pTab */
1098   int op,              /* One of TK_UPDATE, TK_INSERT, TK_DELETE */
1099   ExprList *pChanges,  /* Changes list for any UPDATE OF triggers */
1100   int tr_tm,           /* One of TRIGGER_BEFORE, TRIGGER_AFTER */
1101   Table *pTab,         /* The table to code triggers from */
1102   int reg,             /* The first in an array of registers (see above) */
1103   int orconf,          /* ON CONFLICT policy */
1104   int ignoreJump       /* Instruction to jump to for RAISE(IGNORE) */
1105 ){
1106   Trigger *p;          /* Used to iterate through pTrigger list */
1107
1108   assert( op==TK_UPDATE || op==TK_INSERT || op==TK_DELETE );
1109   assert( tr_tm==TRIGGER_BEFORE || tr_tm==TRIGGER_AFTER );
1110   assert( (op==TK_UPDATE)==(pChanges!=0) );
1111
1112   for(p=pTrigger; p; p=p->pNext){
1113
1114     /* Sanity checking:  The schema for the trigger and for the table are
1115     ** always defined.  The trigger must be in the same schema as the table
1116     ** or else it must be a TEMP trigger. */
1117     assert( p->pSchema!=0 );
1118     assert( p->pTabSchema!=0 );
1119     assert( p->pSchema==p->pTabSchema
1120          || p->pSchema==pParse->db->aDb[1].pSchema );
1121
1122     /* Determine whether we should code this trigger */
1123     if( p->op==op
1124      && p->tr_tm==tr_tm
1125      && checkColumnOverlap(p->pColumns, pChanges)
1126     ){
1127       sqlite3CodeRowTriggerDirect(pParse, p, pTab, reg, orconf, ignoreJump);
1128     }
1129   }
1130 }
1131
1132 /*
1133 ** Triggers may access values stored in the old.* or new.* pseudo-table.
1134 ** This function returns a 32-bit bitmask indicating which columns of the
1135 ** old.* or new.* tables actually are used by triggers. This information
1136 ** may be used by the caller, for example, to avoid having to load the entire
1137 ** old.* record into memory when executing an UPDATE or DELETE command.
1138 **
1139 ** Bit 0 of the returned mask is set if the left-most column of the
1140 ** table may be accessed using an [old|new].<col> reference. Bit 1 is set if
1141 ** the second leftmost column value is required, and so on. If there
1142 ** are more than 32 columns in the table, and at least one of the columns
1143 ** with an index greater than 32 may be accessed, 0xffffffff is returned.
1144 **
1145 ** It is not possible to determine if the old.rowid or new.rowid column is
1146 ** accessed by triggers. The caller must always assume that it is.
1147 **
1148 ** Parameter isNew must be either 1 or 0. If it is 0, then the mask returned
1149 ** applies to the old.* table. If 1, the new.* table.
1150 **
1151 ** Parameter tr_tm must be a mask with one or both of the TRIGGER_BEFORE
1152 ** and TRIGGER_AFTER bits set. Values accessed by BEFORE triggers are only
1153 ** included in the returned mask if the TRIGGER_BEFORE bit is set in the
1154 ** tr_tm parameter. Similarly, values accessed by AFTER triggers are only
1155 ** included in the returned mask if the TRIGGER_AFTER bit is set in tr_tm.
1156 */
1157 u32 sqlite3TriggerColmask(
1158   Parse *pParse,       /* Parse context */
1159   Trigger *pTrigger,   /* List of triggers on table pTab */
1160   ExprList *pChanges,  /* Changes list for any UPDATE OF triggers */
1161   int isNew,           /* 1 for new.* ref mask, 0 for old.* ref mask */
1162   int tr_tm,           /* Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
1163   Table *pTab,         /* The table to code triggers from */
1164   int orconf           /* Default ON CONFLICT policy for trigger steps */
1165 ){
1166   const int op = pChanges ? TK_UPDATE : TK_DELETE;
1167   u32 mask = 0;
1168   Trigger *p;
1169
1170   assert( isNew==1 || isNew==0 );
1171   for(p=pTrigger; p; p=p->pNext){
1172     if( p->op==op && (tr_tm&p->tr_tm)
1173      && checkColumnOverlap(p->pColumns,pChanges)
1174     ){
1175       TriggerPrg *pPrg;
1176       pPrg = getRowTrigger(pParse, p, pTab, orconf);
1177       if( pPrg ){
1178         mask |= pPrg->aColmask[isNew];
1179       }
1180     }
1181   }
1182
1183   return mask;
1184 }
1185
1186 #endif /* !defined(SQLITE_OMIT_TRIGGER) */