sl@0: /*
sl@0: **
sl@0: ** The author disclaims copyright to this source code.  In place of
sl@0: ** a legal notice, here is a blessing:
sl@0: **
sl@0: **    May you do good and not evil.
sl@0: **    May you find forgiveness for yourself and forgive others.
sl@0: **    May you share freely, never taking more than you give.
sl@0: **
sl@0: *************************************************************************
sl@0: **
sl@0: **
sl@0: ** $Id: trigger.c,v 1.129 2008/08/20 16:35:10 drh Exp $
sl@0: */
sl@0: #include "sqliteInt.h"
sl@0: 
sl@0: #ifndef SQLITE_OMIT_TRIGGER
sl@0: /*
sl@0: ** Delete a linked list of TriggerStep structures.
sl@0: */
sl@0: void sqlite3DeleteTriggerStep(sqlite3 *db, TriggerStep *pTriggerStep){
sl@0:   while( pTriggerStep ){
sl@0:     TriggerStep * pTmp = pTriggerStep;
sl@0:     pTriggerStep = pTriggerStep->pNext;
sl@0: 
sl@0:     if( pTmp->target.dyn ) sqlite3DbFree(db, (char*)pTmp->target.z);
sl@0:     sqlite3ExprDelete(db, pTmp->pWhere);
sl@0:     sqlite3ExprListDelete(db, pTmp->pExprList);
sl@0:     sqlite3SelectDelete(db, pTmp->pSelect);
sl@0:     sqlite3IdListDelete(db, pTmp->pIdList);
sl@0: 
sl@0:     sqlite3DbFree(db, pTmp);
sl@0:   }
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** This is called by the parser when it sees a CREATE TRIGGER statement
sl@0: ** up to the point of the BEGIN before the trigger actions.  A Trigger
sl@0: ** structure is generated based on the information available and stored
sl@0: ** in pParse->pNewTrigger.  After the trigger actions have been parsed, the
sl@0: ** sqlite3FinishTrigger() function is called to complete the trigger
sl@0: ** construction process.
sl@0: */
sl@0: void sqlite3BeginTrigger(
sl@0:   Parse *pParse,      /* The parse context of the CREATE TRIGGER statement */
sl@0:   Token *pName1,      /* The name of the trigger */
sl@0:   Token *pName2,      /* The name of the trigger */
sl@0:   int tr_tm,          /* One of TK_BEFORE, TK_AFTER, TK_INSTEAD */
sl@0:   int op,             /* One of TK_INSERT, TK_UPDATE, TK_DELETE */
sl@0:   IdList *pColumns,   /* column list if this is an UPDATE OF trigger */
sl@0:   SrcList *pTableName,/* The name of the table/view the trigger applies to */
sl@0:   Expr *pWhen,        /* WHEN clause */
sl@0:   int isTemp,         /* True if the TEMPORARY keyword is present */
sl@0:   int noErr           /* Suppress errors if the trigger already exists */
sl@0: ){
sl@0:   Trigger *pTrigger = 0;
sl@0:   Table *pTab;
sl@0:   char *zName = 0;        /* Name of the trigger */
sl@0:   sqlite3 *db = pParse->db;
sl@0:   int iDb;                /* The database to store the trigger in */
sl@0:   Token *pName;           /* The unqualified db name */
sl@0:   DbFixer sFix;
sl@0:   int iTabDb;
sl@0: 
sl@0:   assert( pName1!=0 );   /* pName1->z might be NULL, but not pName1 itself */
sl@0:   assert( pName2!=0 );
sl@0:   if( isTemp ){
sl@0:     /* If TEMP was specified, then the trigger name may not be qualified. */
sl@0:     if( pName2->n>0 ){
sl@0:       sqlite3ErrorMsg(pParse, "temporary trigger may not have qualified name");
sl@0:       goto trigger_cleanup;
sl@0:     }
sl@0:     iDb = 1;
sl@0:     pName = pName1;
sl@0:   }else{
sl@0:     /* Figure out the db that the the trigger will be created in */
sl@0:     iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pName);
sl@0:     if( iDb<0 ){
sl@0:       goto trigger_cleanup;
sl@0:     }
sl@0:   }
sl@0: 
sl@0:   /* If the trigger name was unqualified, and the table is a temp table,
sl@0:   ** then set iDb to 1 to create the trigger in the temporary database.
sl@0:   ** If sqlite3SrcListLookup() returns 0, indicating the table does not
sl@0:   ** exist, the error is caught by the block below.
sl@0:   */
sl@0:   if( !pTableName || db->mallocFailed ){
sl@0:     goto trigger_cleanup;
sl@0:   }
sl@0:   pTab = sqlite3SrcListLookup(pParse, pTableName);
sl@0:   if( pName2->n==0 && pTab && pTab->pSchema==db->aDb[1].pSchema ){
sl@0:     iDb = 1;
sl@0:   }
sl@0: 
sl@0:   /* Ensure the table name matches database name and that the table exists */
sl@0:   if( db->mallocFailed ) goto trigger_cleanup;
sl@0:   assert( pTableName->nSrc==1 );
sl@0:   if( sqlite3FixInit(&sFix, pParse, iDb, "trigger", pName) && 
sl@0:       sqlite3FixSrcList(&sFix, pTableName) ){
sl@0:     goto trigger_cleanup;
sl@0:   }
sl@0:   pTab = sqlite3SrcListLookup(pParse, pTableName);
sl@0:   if( !pTab ){
sl@0:     /* The table does not exist. */
sl@0:     goto trigger_cleanup;
sl@0:   }
sl@0:   if( IsVirtual(pTab) ){
sl@0:     sqlite3ErrorMsg(pParse, "cannot create triggers on virtual tables");
sl@0:     goto trigger_cleanup;
sl@0:   }
sl@0: 
sl@0:   /* Check that the trigger name is not reserved and that no trigger of the
sl@0:   ** specified name exists */
sl@0:   zName = sqlite3NameFromToken(db, pName);
sl@0:   if( !zName || SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
sl@0:     goto trigger_cleanup;
sl@0:   }
sl@0:   if( sqlite3HashFind(&(db->aDb[iDb].pSchema->trigHash), zName,strlen(zName)) ){
sl@0:     if( !noErr ){
sl@0:       sqlite3ErrorMsg(pParse, "trigger %T already exists", pName);
sl@0:     }
sl@0:     goto trigger_cleanup;
sl@0:   }
sl@0: 
sl@0:   /* Do not create a trigger on a system table */
sl@0:   if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 ){
sl@0:     sqlite3ErrorMsg(pParse, "cannot create trigger on system table");
sl@0:     pParse->nErr++;
sl@0:     goto trigger_cleanup;
sl@0:   }
sl@0: 
sl@0:   /* INSTEAD of triggers are only for views and views only support INSTEAD
sl@0:   ** of triggers.
sl@0:   */
sl@0:   if( pTab->pSelect && tr_tm!=TK_INSTEAD ){
sl@0:     sqlite3ErrorMsg(pParse, "cannot create %s trigger on view: %S", 
sl@0:         (tr_tm == TK_BEFORE)?"BEFORE":"AFTER", pTableName, 0);
sl@0:     goto trigger_cleanup;
sl@0:   }
sl@0:   if( !pTab->pSelect && tr_tm==TK_INSTEAD ){
sl@0:     sqlite3ErrorMsg(pParse, "cannot create INSTEAD OF"
sl@0:         " trigger on table: %S", pTableName, 0);
sl@0:     goto trigger_cleanup;
sl@0:   }
sl@0:   iTabDb = sqlite3SchemaToIndex(db, pTab->pSchema);
sl@0: 
sl@0: #ifndef SQLITE_OMIT_AUTHORIZATION
sl@0:   {
sl@0:     int code = SQLITE_CREATE_TRIGGER;
sl@0:     const char *zDb = db->aDb[iTabDb].zName;
sl@0:     const char *zDbTrig = isTemp ? db->aDb[1].zName : zDb;
sl@0:     if( iTabDb==1 || isTemp ) code = SQLITE_CREATE_TEMP_TRIGGER;
sl@0:     if( sqlite3AuthCheck(pParse, code, zName, pTab->zName, zDbTrig) ){
sl@0:       goto trigger_cleanup;
sl@0:     }
sl@0:     if( sqlite3AuthCheck(pParse, SQLITE_INSERT, SCHEMA_TABLE(iTabDb),0,zDb)){
sl@0:       goto trigger_cleanup;
sl@0:     }
sl@0:   }
sl@0: #endif
sl@0: 
sl@0:   /* INSTEAD OF triggers can only appear on views and BEFORE triggers
sl@0:   ** cannot appear on views.  So we might as well translate every
sl@0:   ** INSTEAD OF trigger into a BEFORE trigger.  It simplifies code
sl@0:   ** elsewhere.
sl@0:   */
sl@0:   if (tr_tm == TK_INSTEAD){
sl@0:     tr_tm = TK_BEFORE;
sl@0:   }
sl@0: 
sl@0:   /* Build the Trigger object */
sl@0:   pTrigger = (Trigger*)sqlite3DbMallocZero(db, sizeof(Trigger));
sl@0:   if( pTrigger==0 ) goto trigger_cleanup;
sl@0:   pTrigger->name = zName;
sl@0:   zName = 0;
sl@0:   pTrigger->table = sqlite3DbStrDup(db, pTableName->a[0].zName);
sl@0:   pTrigger->pSchema = db->aDb[iDb].pSchema;
sl@0:   pTrigger->pTabSchema = pTab->pSchema;
sl@0:   pTrigger->op = op;
sl@0:   pTrigger->tr_tm = tr_tm==TK_BEFORE ? TRIGGER_BEFORE : TRIGGER_AFTER;
sl@0:   pTrigger->pWhen = sqlite3ExprDup(db, pWhen);
sl@0:   pTrigger->pColumns = sqlite3IdListDup(db, pColumns);
sl@0:   sqlite3TokenCopy(db, &pTrigger->nameToken,pName);
sl@0:   assert( pParse->pNewTrigger==0 );
sl@0:   pParse->pNewTrigger = pTrigger;
sl@0: 
sl@0: trigger_cleanup:
sl@0:   sqlite3DbFree(db, zName);
sl@0:   sqlite3SrcListDelete(db, pTableName);
sl@0:   sqlite3IdListDelete(db, pColumns);
sl@0:   sqlite3ExprDelete(db, pWhen);
sl@0:   if( !pParse->pNewTrigger ){
sl@0:     sqlite3DeleteTrigger(db, pTrigger);
sl@0:   }else{
sl@0:     assert( pParse->pNewTrigger==pTrigger );
sl@0:   }
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** This routine is called after all of the trigger actions have been parsed
sl@0: ** in order to complete the process of building the trigger.
sl@0: */
sl@0: void sqlite3FinishTrigger(
sl@0:   Parse *pParse,          /* Parser context */
sl@0:   TriggerStep *pStepList, /* The triggered program */
sl@0:   Token *pAll             /* Token that describes the complete CREATE TRIGGER */
sl@0: ){
sl@0:   Trigger *pTrig = 0;     /* The trigger whose construction is finishing up */
sl@0:   sqlite3 *db = pParse->db;  /* The database */
sl@0:   DbFixer sFix;
sl@0:   int iDb;                   /* Database containing the trigger */
sl@0: 
sl@0:   pTrig = pParse->pNewTrigger;
sl@0:   pParse->pNewTrigger = 0;
sl@0:   if( pParse->nErr || !pTrig ) goto triggerfinish_cleanup;
sl@0:   iDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema);
sl@0:   pTrig->step_list = pStepList;
sl@0:   while( pStepList ){
sl@0:     pStepList->pTrig = pTrig;
sl@0:     pStepList = pStepList->pNext;
sl@0:   }
sl@0:   if( sqlite3FixInit(&sFix, pParse, iDb, "trigger", &pTrig->nameToken) 
sl@0:           && sqlite3FixTriggerStep(&sFix, pTrig->step_list) ){
sl@0:     goto triggerfinish_cleanup;
sl@0:   }
sl@0: 
sl@0:   /* if we are not initializing, and this trigger is not on a TEMP table, 
sl@0:   ** build the sqlite_master entry
sl@0:   */
sl@0:   if( !db->init.busy ){
sl@0:     Vdbe *v;
sl@0:     char *z;
sl@0: 
sl@0:     /* Make an entry in the sqlite_master table */
sl@0:     v = sqlite3GetVdbe(pParse);
sl@0:     if( v==0 ) goto triggerfinish_cleanup;
sl@0:     sqlite3BeginWriteOperation(pParse, 0, iDb);
sl@0:     z = sqlite3DbStrNDup(db, (char*)pAll->z, pAll->n);
sl@0:     sqlite3NestedParse(pParse,
sl@0:        "INSERT INTO %Q.%s VALUES('trigger',%Q,%Q,0,'CREATE TRIGGER %q')",
sl@0:        db->aDb[iDb].zName, SCHEMA_TABLE(iDb), pTrig->name,
sl@0:        pTrig->table, z);
sl@0:     sqlite3DbFree(db, z);
sl@0:     sqlite3ChangeCookie(pParse, iDb);
sl@0:     sqlite3VdbeAddOp4(v, OP_ParseSchema, iDb, 0, 0, sqlite3MPrintf(
sl@0:         db, "type='trigger' AND name='%q'", pTrig->name), P4_DYNAMIC
sl@0:     );
sl@0:   }
sl@0: 
sl@0:   if( db->init.busy ){
sl@0:     int n;
sl@0:     Table *pTab;
sl@0:     Trigger *pDel;
sl@0:     pDel = sqlite3HashInsert(&db->aDb[iDb].pSchema->trigHash, 
sl@0:                      pTrig->name, strlen(pTrig->name), pTrig);
sl@0:     if( pDel ){
sl@0:       assert( pDel==pTrig );
sl@0:       db->mallocFailed = 1;
sl@0:       goto triggerfinish_cleanup;
sl@0:     }
sl@0:     n = strlen(pTrig->table) + 1;
sl@0:     pTab = sqlite3HashFind(&pTrig->pTabSchema->tblHash, pTrig->table, n);
sl@0:     assert( pTab!=0 );
sl@0:     pTrig->pNext = pTab->pTrigger;
sl@0:     pTab->pTrigger = pTrig;
sl@0:     pTrig = 0;
sl@0:   }
sl@0: 
sl@0: triggerfinish_cleanup:
sl@0:   sqlite3DeleteTrigger(db, pTrig);
sl@0:   assert( !pParse->pNewTrigger );
sl@0:   sqlite3DeleteTriggerStep(db, pStepList);
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Make a copy of all components of the given trigger step.  This has
sl@0: ** the effect of copying all Expr.token.z values into memory obtained
sl@0: ** from sqlite3_malloc().  As initially created, the Expr.token.z values
sl@0: ** all point to the input string that was fed to the parser.  But that
sl@0: ** string is ephemeral - it will go away as soon as the sqlite3_exec()
sl@0: ** call that started the parser exits.  This routine makes a persistent
sl@0: ** copy of all the Expr.token.z strings so that the TriggerStep structure
sl@0: ** will be valid even after the sqlite3_exec() call returns.
sl@0: */
sl@0: static void sqlitePersistTriggerStep(sqlite3 *db, TriggerStep *p){
sl@0:   if( p->target.z ){
sl@0:     p->target.z = (u8*)sqlite3DbStrNDup(db, (char*)p->target.z, p->target.n);
sl@0:     p->target.dyn = 1;
sl@0:   }
sl@0:   if( p->pSelect ){
sl@0:     Select *pNew = sqlite3SelectDup(db, p->pSelect);
sl@0:     sqlite3SelectDelete(db, p->pSelect);
sl@0:     p->pSelect = pNew;
sl@0:   }
sl@0:   if( p->pWhere ){
sl@0:     Expr *pNew = sqlite3ExprDup(db, p->pWhere);
sl@0:     sqlite3ExprDelete(db, p->pWhere);
sl@0:     p->pWhere = pNew;
sl@0:   }
sl@0:   if( p->pExprList ){
sl@0:     ExprList *pNew = sqlite3ExprListDup(db, p->pExprList);
sl@0:     sqlite3ExprListDelete(db, p->pExprList);
sl@0:     p->pExprList = pNew;
sl@0:   }
sl@0:   if( p->pIdList ){
sl@0:     IdList *pNew = sqlite3IdListDup(db, p->pIdList);
sl@0:     sqlite3IdListDelete(db, p->pIdList);
sl@0:     p->pIdList = pNew;
sl@0:   }
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Turn a SELECT statement (that the pSelect parameter points to) into
sl@0: ** a trigger step.  Return a pointer to a TriggerStep structure.
sl@0: **
sl@0: ** The parser calls this routine when it finds a SELECT statement in
sl@0: ** body of a TRIGGER.  
sl@0: */
sl@0: TriggerStep *sqlite3TriggerSelectStep(sqlite3 *db, Select *pSelect){
sl@0:   TriggerStep *pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep));
sl@0:   if( pTriggerStep==0 ) {
sl@0:     sqlite3SelectDelete(db, pSelect);
sl@0:     return 0;
sl@0:   }
sl@0: 
sl@0:   pTriggerStep->op = TK_SELECT;
sl@0:   pTriggerStep->pSelect = pSelect;
sl@0:   pTriggerStep->orconf = OE_Default;
sl@0:   sqlitePersistTriggerStep(db, pTriggerStep);
sl@0: 
sl@0:   return pTriggerStep;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Build a trigger step out of an INSERT statement.  Return a pointer
sl@0: ** to the new trigger step.
sl@0: **
sl@0: ** The parser calls this routine when it sees an INSERT inside the
sl@0: ** body of a trigger.
sl@0: */
sl@0: TriggerStep *sqlite3TriggerInsertStep(
sl@0:   sqlite3 *db,        /* The database connection */
sl@0:   Token *pTableName,  /* Name of the table into which we insert */
sl@0:   IdList *pColumn,    /* List of columns in pTableName to insert into */
sl@0:   ExprList *pEList,   /* The VALUE clause: a list of values to be inserted */
sl@0:   Select *pSelect,    /* A SELECT statement that supplies values */
sl@0:   int orconf          /* The conflict algorithm (OE_Abort, OE_Replace, etc.) */
sl@0: ){
sl@0:   TriggerStep *pTriggerStep;
sl@0: 
sl@0:   assert(pEList == 0 || pSelect == 0);
sl@0:   assert(pEList != 0 || pSelect != 0 || db->mallocFailed);
sl@0: 
sl@0:   pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep));
sl@0:   if( pTriggerStep ){
sl@0:     pTriggerStep->op = TK_INSERT;
sl@0:     pTriggerStep->pSelect = pSelect;
sl@0:     pTriggerStep->target  = *pTableName;
sl@0:     pTriggerStep->pIdList = pColumn;
sl@0:     pTriggerStep->pExprList = pEList;
sl@0:     pTriggerStep->orconf = orconf;
sl@0:     sqlitePersistTriggerStep(db, pTriggerStep);
sl@0:   }else{
sl@0:     sqlite3IdListDelete(db, pColumn);
sl@0:     sqlite3ExprListDelete(db, pEList);
sl@0:     sqlite3SelectDelete(db, pSelect);
sl@0:   }
sl@0: 
sl@0:   return pTriggerStep;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Construct a trigger step that implements an UPDATE statement and return
sl@0: ** a pointer to that trigger step.  The parser calls this routine when it
sl@0: ** sees an UPDATE statement inside the body of a CREATE TRIGGER.
sl@0: */
sl@0: TriggerStep *sqlite3TriggerUpdateStep(
sl@0:   sqlite3 *db,         /* The database connection */
sl@0:   Token *pTableName,   /* Name of the table to be updated */
sl@0:   ExprList *pEList,    /* The SET clause: list of column and new values */
sl@0:   Expr *pWhere,        /* The WHERE clause */
sl@0:   int orconf           /* The conflict algorithm. (OE_Abort, OE_Ignore, etc) */
sl@0: ){
sl@0:   TriggerStep *pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep));
sl@0:   if( pTriggerStep==0 ){
sl@0:      sqlite3ExprListDelete(db, pEList);
sl@0:      sqlite3ExprDelete(db, pWhere);
sl@0:      return 0;
sl@0:   }
sl@0: 
sl@0:   pTriggerStep->op = TK_UPDATE;
sl@0:   pTriggerStep->target  = *pTableName;
sl@0:   pTriggerStep->pExprList = pEList;
sl@0:   pTriggerStep->pWhere = pWhere;
sl@0:   pTriggerStep->orconf = orconf;
sl@0:   sqlitePersistTriggerStep(db, pTriggerStep);
sl@0: 
sl@0:   return pTriggerStep;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Construct a trigger step that implements a DELETE statement and return
sl@0: ** a pointer to that trigger step.  The parser calls this routine when it
sl@0: ** sees a DELETE statement inside the body of a CREATE TRIGGER.
sl@0: */
sl@0: TriggerStep *sqlite3TriggerDeleteStep(
sl@0:   sqlite3 *db,            /* Database connection */
sl@0:   Token *pTableName,      /* The table from which rows are deleted */
sl@0:   Expr *pWhere            /* The WHERE clause */
sl@0: ){
sl@0:   TriggerStep *pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep));
sl@0:   if( pTriggerStep==0 ){
sl@0:     sqlite3ExprDelete(db, pWhere);
sl@0:     return 0;
sl@0:   }
sl@0: 
sl@0:   pTriggerStep->op = TK_DELETE;
sl@0:   pTriggerStep->target  = *pTableName;
sl@0:   pTriggerStep->pWhere = pWhere;
sl@0:   pTriggerStep->orconf = OE_Default;
sl@0:   sqlitePersistTriggerStep(db, pTriggerStep);
sl@0: 
sl@0:   return pTriggerStep;
sl@0: }
sl@0: 
sl@0: /* 
sl@0: ** Recursively delete a Trigger structure
sl@0: */
sl@0: void sqlite3DeleteTrigger(sqlite3 *db, Trigger *pTrigger){
sl@0:   if( pTrigger==0 ) return;
sl@0:   sqlite3DeleteTriggerStep(db, pTrigger->step_list);
sl@0:   sqlite3DbFree(db, pTrigger->name);
sl@0:   sqlite3DbFree(db, pTrigger->table);
sl@0:   sqlite3ExprDelete(db, pTrigger->pWhen);
sl@0:   sqlite3IdListDelete(db, pTrigger->pColumns);
sl@0:   if( pTrigger->nameToken.dyn ) sqlite3DbFree(db, (char*)pTrigger->nameToken.z);
sl@0:   sqlite3DbFree(db, pTrigger);
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** This function is called to drop a trigger from the database schema. 
sl@0: **
sl@0: ** This may be called directly from the parser and therefore identifies
sl@0: ** the trigger by name.  The sqlite3DropTriggerPtr() routine does the
sl@0: ** same job as this routine except it takes a pointer to the trigger
sl@0: ** instead of the trigger name.
sl@0: **/
sl@0: void sqlite3DropTrigger(Parse *pParse, SrcList *pName, int noErr){
sl@0:   Trigger *pTrigger = 0;
sl@0:   int i;
sl@0:   const char *zDb;
sl@0:   const char *zName;
sl@0:   int nName;
sl@0:   sqlite3 *db = pParse->db;
sl@0: 
sl@0:   if( db->mallocFailed ) goto drop_trigger_cleanup;
sl@0:   if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
sl@0:     goto drop_trigger_cleanup;
sl@0:   }
sl@0: 
sl@0:   assert( pName->nSrc==1 );
sl@0:   zDb = pName->a[0].zDatabase;
sl@0:   zName = pName->a[0].zName;
sl@0:   nName = strlen(zName);
sl@0:   for(i=OMIT_TEMPDB; i<db->nDb; i++){
sl@0:     int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
sl@0:     if( zDb && sqlite3StrICmp(db->aDb[j].zName, zDb) ) continue;
sl@0:     pTrigger = sqlite3HashFind(&(db->aDb[j].pSchema->trigHash), zName, nName);
sl@0:     if( pTrigger ) break;
sl@0:   }
sl@0:   if( !pTrigger ){
sl@0:     if( !noErr ){
sl@0:       sqlite3ErrorMsg(pParse, "no such trigger: %S", pName, 0);
sl@0:     }
sl@0:     goto drop_trigger_cleanup;
sl@0:   }
sl@0:   sqlite3DropTriggerPtr(pParse, pTrigger);
sl@0: 
sl@0: drop_trigger_cleanup:
sl@0:   sqlite3SrcListDelete(db, pName);
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Return a pointer to the Table structure for the table that a trigger
sl@0: ** is set on.
sl@0: */
sl@0: static Table *tableOfTrigger(Trigger *pTrigger){
sl@0:   int n = strlen(pTrigger->table) + 1;
sl@0:   return sqlite3HashFind(&pTrigger->pTabSchema->tblHash, pTrigger->table, n);
sl@0: }
sl@0: 
sl@0: 
sl@0: /*
sl@0: ** Drop a trigger given a pointer to that trigger. 
sl@0: */
sl@0: void sqlite3DropTriggerPtr(Parse *pParse, Trigger *pTrigger){
sl@0:   Table   *pTable;
sl@0:   Vdbe *v;
sl@0:   sqlite3 *db = pParse->db;
sl@0:   int iDb;
sl@0: 
sl@0:   iDb = sqlite3SchemaToIndex(pParse->db, pTrigger->pSchema);
sl@0:   assert( iDb>=0 && iDb<db->nDb );
sl@0:   pTable = tableOfTrigger(pTrigger);
sl@0:   assert( pTable );
sl@0:   assert( pTable->pSchema==pTrigger->pSchema || iDb==1 );
sl@0: #ifndef SQLITE_OMIT_AUTHORIZATION
sl@0:   {
sl@0:     int code = SQLITE_DROP_TRIGGER;
sl@0:     const char *zDb = db->aDb[iDb].zName;
sl@0:     const char *zTab = SCHEMA_TABLE(iDb);
sl@0:     if( iDb==1 ) code = SQLITE_DROP_TEMP_TRIGGER;
sl@0:     if( sqlite3AuthCheck(pParse, code, pTrigger->name, pTable->zName, zDb) ||
sl@0:       sqlite3AuthCheck(pParse, SQLITE_DELETE, zTab, 0, zDb) ){
sl@0:       return;
sl@0:     }
sl@0:   }
sl@0: #endif
sl@0: 
sl@0:   /* Generate code to destroy the database record of the trigger.
sl@0:   */
sl@0:   assert( pTable!=0 );
sl@0:   if( (v = sqlite3GetVdbe(pParse))!=0 ){
sl@0:     int base;
sl@0:     static const VdbeOpList dropTrigger[] = {
sl@0:       { OP_Rewind,     0, ADDR(9),  0},
sl@0:       { OP_String8,    0, 1,        0}, /* 1 */
sl@0:       { OP_Column,     0, 1,        2},
sl@0:       { OP_Ne,         2, ADDR(8),  1},
sl@0:       { OP_String8,    0, 1,        0}, /* 4: "trigger" */
sl@0:       { OP_Column,     0, 0,        2},
sl@0:       { OP_Ne,         2, ADDR(8),  1},
sl@0:       { OP_Delete,     0, 0,        0},
sl@0:       { OP_Next,       0, ADDR(1),  0}, /* 8 */
sl@0:     };
sl@0: 
sl@0:     sqlite3BeginWriteOperation(pParse, 0, iDb);
sl@0:     sqlite3OpenMasterTable(pParse, iDb);
sl@0:     base = sqlite3VdbeAddOpList(v,  ArraySize(dropTrigger), dropTrigger);
sl@0:     sqlite3VdbeChangeP4(v, base+1, pTrigger->name, 0);
sl@0:     sqlite3VdbeChangeP4(v, base+4, "trigger", P4_STATIC);
sl@0:     sqlite3ChangeCookie(pParse, iDb);
sl@0:     sqlite3VdbeAddOp2(v, OP_Close, 0, 0);
sl@0:     sqlite3VdbeAddOp4(v, OP_DropTrigger, iDb, 0, 0, pTrigger->name, 0);
sl@0:   }
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Remove a trigger from the hash tables of the sqlite* pointer.
sl@0: */
sl@0: void sqlite3UnlinkAndDeleteTrigger(sqlite3 *db, int iDb, const char *zName){
sl@0:   Trigger *pTrigger;
sl@0:   int nName = strlen(zName);
sl@0:   pTrigger = sqlite3HashInsert(&(db->aDb[iDb].pSchema->trigHash),
sl@0:                                zName, nName, 0);
sl@0:   if( pTrigger ){
sl@0:     Table *pTable = tableOfTrigger(pTrigger);
sl@0:     assert( pTable!=0 );
sl@0:     if( pTable->pTrigger == pTrigger ){
sl@0:       pTable->pTrigger = pTrigger->pNext;
sl@0:     }else{
sl@0:       Trigger *cc = pTable->pTrigger;
sl@0:       while( cc ){ 
sl@0:         if( cc->pNext == pTrigger ){
sl@0:           cc->pNext = cc->pNext->pNext;
sl@0:           break;
sl@0:         }
sl@0:         cc = cc->pNext;
sl@0:       }
sl@0:       assert(cc);
sl@0:     }
sl@0:     sqlite3DeleteTrigger(db, pTrigger);
sl@0:     db->flags |= SQLITE_InternChanges;
sl@0:   }
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** pEList is the SET clause of an UPDATE statement.  Each entry
sl@0: ** in pEList is of the format <id>=<expr>.  If any of the entries
sl@0: ** in pEList have an <id> which matches an identifier in pIdList,
sl@0: ** then return TRUE.  If pIdList==NULL, then it is considered a
sl@0: ** wildcard that matches anything.  Likewise if pEList==NULL then
sl@0: ** it matches anything so always return true.  Return false only
sl@0: ** if there is no match.
sl@0: */
sl@0: static int checkColumnOverLap(IdList *pIdList, ExprList *pEList){
sl@0:   int e;
sl@0:   if( !pIdList || !pEList ) return 1;
sl@0:   for(e=0; e<pEList->nExpr; e++){
sl@0:     if( sqlite3IdListIndex(pIdList, pEList->a[e].zName)>=0 ) return 1;
sl@0:   }
sl@0:   return 0; 
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Return a bit vector to indicate what kind of triggers exist for operation
sl@0: ** "op" on table pTab.  If pChanges is not NULL then it is a list of columns
sl@0: ** that are being updated.  Triggers only match if the ON clause of the
sl@0: ** trigger definition overlaps the set of columns being updated.
sl@0: **
sl@0: ** The returned bit vector is some combination of TRIGGER_BEFORE and
sl@0: ** TRIGGER_AFTER.
sl@0: */
sl@0: int sqlite3TriggersExist(
sl@0:   Parse *pParse,          /* Used to check for recursive triggers */
sl@0:   Table *pTab,            /* The table the contains the triggers */
sl@0:   int op,                 /* one of TK_DELETE, TK_INSERT, TK_UPDATE */
sl@0:   ExprList *pChanges      /* Columns that change in an UPDATE statement */
sl@0: ){
sl@0:   Trigger *pTrigger;
sl@0:   int mask = 0;
sl@0: 
sl@0:   pTrigger = IsVirtual(pTab) ? 0 : pTab->pTrigger;
sl@0:   while( pTrigger ){
sl@0:     if( pTrigger->op==op && checkColumnOverLap(pTrigger->pColumns, pChanges) ){
sl@0:       mask |= pTrigger->tr_tm;
sl@0:     }
sl@0:     pTrigger = pTrigger->pNext;
sl@0:   }
sl@0:   return mask;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Convert the pStep->target token into a SrcList and return a pointer
sl@0: ** to that SrcList.
sl@0: **
sl@0: ** This routine adds a specific database name, if needed, to the target when
sl@0: ** forming the SrcList.  This prevents a trigger in one database from
sl@0: ** referring to a target in another database.  An exception is when the
sl@0: ** trigger is in TEMP in which case it can refer to any other database it
sl@0: ** wants.
sl@0: */
sl@0: static SrcList *targetSrcList(
sl@0:   Parse *pParse,       /* The parsing context */
sl@0:   TriggerStep *pStep   /* The trigger containing the target token */
sl@0: ){
sl@0:   Token sDb;           /* Dummy database name token */
sl@0:   int iDb;             /* Index of the database to use */
sl@0:   SrcList *pSrc;       /* SrcList to be returned */
sl@0: 
sl@0:   iDb = sqlite3SchemaToIndex(pParse->db, pStep->pTrig->pSchema);
sl@0:   if( iDb==0 || iDb>=2 ){
sl@0:     assert( iDb<pParse->db->nDb );
sl@0:     sDb.z = (u8*)pParse->db->aDb[iDb].zName;
sl@0:     sDb.n = strlen((char*)sDb.z);
sl@0:     pSrc = sqlite3SrcListAppend(pParse->db, 0, &sDb, &pStep->target);
sl@0:   } else {
sl@0:     pSrc = sqlite3SrcListAppend(pParse->db, 0, &pStep->target, 0);
sl@0:   }
sl@0:   return pSrc;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Generate VDBE code for zero or more statements inside the body of a
sl@0: ** trigger.  
sl@0: */
sl@0: static int codeTriggerProgram(
sl@0:   Parse *pParse,            /* The parser context */
sl@0:   TriggerStep *pStepList,   /* List of statements inside the trigger body */
sl@0:   int orconfin              /* Conflict algorithm. (OE_Abort, etc) */  
sl@0: ){
sl@0:   TriggerStep * pTriggerStep = pStepList;
sl@0:   int orconf;
sl@0:   Vdbe *v = pParse->pVdbe;
sl@0:   sqlite3 *db = pParse->db;
sl@0: 
sl@0:   assert( pTriggerStep!=0 );
sl@0:   assert( v!=0 );
sl@0:   sqlite3VdbeAddOp2(v, OP_ContextPush, 0, 0);
sl@0:   VdbeComment((v, "begin trigger %s", pStepList->pTrig->name));
sl@0:   while( pTriggerStep ){
sl@0:     orconf = (orconfin == OE_Default)?pTriggerStep->orconf:orconfin;
sl@0:     pParse->trigStack->orconf = orconf;
sl@0:     switch( pTriggerStep->op ){
sl@0:       case TK_SELECT: {
sl@0:         Select *ss = sqlite3SelectDup(db, pTriggerStep->pSelect);
sl@0:         if( ss ){
sl@0:           SelectDest dest;
sl@0: 
sl@0:           sqlite3SelectDestInit(&dest, SRT_Discard, 0);
sl@0:           sqlite3Select(pParse, ss, &dest);
sl@0:           sqlite3SelectDelete(db, ss);
sl@0:         }
sl@0:         break;
sl@0:       }
sl@0:       case TK_UPDATE: {
sl@0:         SrcList *pSrc;
sl@0:         pSrc = targetSrcList(pParse, pTriggerStep);
sl@0:         sqlite3VdbeAddOp2(v, OP_ResetCount, 0, 0);
sl@0:         sqlite3Update(pParse, pSrc,
sl@0:                 sqlite3ExprListDup(db, pTriggerStep->pExprList), 
sl@0:                 sqlite3ExprDup(db, pTriggerStep->pWhere), orconf);
sl@0:         sqlite3VdbeAddOp2(v, OP_ResetCount, 1, 0);
sl@0:         break;
sl@0:       }
sl@0:       case TK_INSERT: {
sl@0:         SrcList *pSrc;
sl@0:         pSrc = targetSrcList(pParse, pTriggerStep);
sl@0:         sqlite3VdbeAddOp2(v, OP_ResetCount, 0, 0);
sl@0:         sqlite3Insert(pParse, pSrc,
sl@0:           sqlite3ExprListDup(db, pTriggerStep->pExprList), 
sl@0:           sqlite3SelectDup(db, pTriggerStep->pSelect), 
sl@0:           sqlite3IdListDup(db, pTriggerStep->pIdList), orconf);
sl@0:         sqlite3VdbeAddOp2(v, OP_ResetCount, 1, 0);
sl@0:         break;
sl@0:       }
sl@0:       case TK_DELETE: {
sl@0:         SrcList *pSrc;
sl@0:         sqlite3VdbeAddOp2(v, OP_ResetCount, 0, 0);
sl@0:         pSrc = targetSrcList(pParse, pTriggerStep);
sl@0:         sqlite3DeleteFrom(pParse, pSrc, 
sl@0:                           sqlite3ExprDup(db, pTriggerStep->pWhere));
sl@0:         sqlite3VdbeAddOp2(v, OP_ResetCount, 1, 0);
sl@0:         break;
sl@0:       }
sl@0:       default:
sl@0:         assert(0);
sl@0:     } 
sl@0:     pTriggerStep = pTriggerStep->pNext;
sl@0:   }
sl@0:   sqlite3VdbeAddOp2(v, OP_ContextPop, 0, 0);
sl@0:   VdbeComment((v, "end trigger %s", pStepList->pTrig->name));
sl@0: 
sl@0:   return 0;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** This is called to code FOR EACH ROW triggers.
sl@0: **
sl@0: ** When the code that this function generates is executed, the following 
sl@0: ** must be true:
sl@0: **
sl@0: ** 1. No cursors may be open in the main database.  (But newIdx and oldIdx
sl@0: **    can be indices of cursors in temporary tables.  See below.)
sl@0: **
sl@0: ** 2. If the triggers being coded are ON INSERT or ON UPDATE triggers, then
sl@0: **    a temporary vdbe cursor (index newIdx) must be open and pointing at
sl@0: **    a row containing values to be substituted for new.* expressions in the
sl@0: **    trigger program(s).
sl@0: **
sl@0: ** 3. If the triggers being coded are ON DELETE or ON UPDATE triggers, then
sl@0: **    a temporary vdbe cursor (index oldIdx) must be open and pointing at
sl@0: **    a row containing values to be substituted for old.* expressions in the
sl@0: **    trigger program(s).
sl@0: **
sl@0: ** If they are not NULL, the piOldColMask and piNewColMask output variables
sl@0: ** are set to values that describe the columns used by the trigger program
sl@0: ** in the OLD.* and NEW.* tables respectively. If column N of the 
sl@0: ** pseudo-table is read at least once, the corresponding bit of the output
sl@0: ** mask is set. If a column with an index greater than 32 is read, the
sl@0: ** output mask is set to the special value 0xffffffff.
sl@0: **
sl@0: */
sl@0: int sqlite3CodeRowTrigger(
sl@0:   Parse *pParse,       /* Parse context */
sl@0:   int op,              /* One of TK_UPDATE, TK_INSERT, TK_DELETE */
sl@0:   ExprList *pChanges,  /* Changes list for any UPDATE OF triggers */
sl@0:   int tr_tm,           /* One of TRIGGER_BEFORE, TRIGGER_AFTER */
sl@0:   Table *pTab,         /* The table to code triggers from */
sl@0:   int newIdx,          /* The indice of the "new" row to access */
sl@0:   int oldIdx,          /* The indice of the "old" row to access */
sl@0:   int orconf,          /* ON CONFLICT policy */
sl@0:   int ignoreJump,      /* Instruction to jump to for RAISE(IGNORE) */
sl@0:   u32 *piOldColMask,   /* OUT: Mask of columns used from the OLD.* table */
sl@0:   u32 *piNewColMask    /* OUT: Mask of columns used from the NEW.* table */
sl@0: ){
sl@0:   Trigger *p;
sl@0:   sqlite3 *db = pParse->db;
sl@0:   TriggerStack trigStackEntry;
sl@0: 
sl@0:   trigStackEntry.oldColMask = 0;
sl@0:   trigStackEntry.newColMask = 0;
sl@0: 
sl@0:   assert(op == TK_UPDATE || op == TK_INSERT || op == TK_DELETE);
sl@0:   assert(tr_tm == TRIGGER_BEFORE || tr_tm == TRIGGER_AFTER );
sl@0: 
sl@0:   assert(newIdx != -1 || oldIdx != -1);
sl@0: 
sl@0:   for(p=pTab->pTrigger; p; p=p->pNext){
sl@0:     int fire_this = 0;
sl@0: 
sl@0:     /* Determine whether we should code this trigger */
sl@0:     if( 
sl@0:       p->op==op && 
sl@0:       p->tr_tm==tr_tm && 
sl@0:       (p->pSchema==p->pTabSchema || p->pSchema==db->aDb[1].pSchema) &&
sl@0:       (op!=TK_UPDATE||!p->pColumns||checkColumnOverLap(p->pColumns,pChanges))
sl@0:     ){
sl@0:       TriggerStack *pS;      /* Pointer to trigger-stack entry */
sl@0:       for(pS=pParse->trigStack; pS && p!=pS->pTrigger; pS=pS->pNext){}
sl@0:       if( !pS ){
sl@0:         fire_this = 1;
sl@0:       }
sl@0: #if 0    /* Give no warning for recursive triggers.  Just do not do them */
sl@0:       else{
sl@0:         sqlite3ErrorMsg(pParse, "recursive triggers not supported (%s)",
sl@0:             p->name);
sl@0:         return SQLITE_ERROR;
sl@0:       }
sl@0: #endif
sl@0:     }
sl@0:  
sl@0:     if( fire_this ){
sl@0:       int endTrigger;
sl@0:       Expr * whenExpr;
sl@0:       AuthContext sContext;
sl@0:       NameContext sNC;
sl@0: 
sl@0: #ifndef SQLITE_OMIT_TRACE
sl@0:       sqlite3VdbeAddOp4(pParse->pVdbe, OP_Trace, 0, 0, 0,
sl@0:                         sqlite3MPrintf(db, "-- TRIGGER %s", p->name),
sl@0:                         P4_DYNAMIC);
sl@0: #endif
sl@0:       memset(&sNC, 0, sizeof(sNC));
sl@0:       sNC.pParse = pParse;
sl@0: 
sl@0:       /* Push an entry on to the trigger stack */
sl@0:       trigStackEntry.pTrigger = p;
sl@0:       trigStackEntry.newIdx = newIdx;
sl@0:       trigStackEntry.oldIdx = oldIdx;
sl@0:       trigStackEntry.pTab = pTab;
sl@0:       trigStackEntry.pNext = pParse->trigStack;
sl@0:       trigStackEntry.ignoreJump = ignoreJump;
sl@0:       pParse->trigStack = &trigStackEntry;
sl@0:       sqlite3AuthContextPush(pParse, &sContext, p->name);
sl@0: 
sl@0:       /* code the WHEN clause */
sl@0:       endTrigger = sqlite3VdbeMakeLabel(pParse->pVdbe);
sl@0:       whenExpr = sqlite3ExprDup(db, p->pWhen);
sl@0:       if( db->mallocFailed || sqlite3ResolveExprNames(&sNC, whenExpr) ){
sl@0:         pParse->trigStack = trigStackEntry.pNext;
sl@0:         sqlite3ExprDelete(db, whenExpr);
sl@0:         return 1;
sl@0:       }
sl@0:       sqlite3ExprIfFalse(pParse, whenExpr, endTrigger, SQLITE_JUMPIFNULL);
sl@0:       sqlite3ExprDelete(db, whenExpr);
sl@0: 
sl@0:       codeTriggerProgram(pParse, p->step_list, orconf); 
sl@0: 
sl@0:       /* Pop the entry off the trigger stack */
sl@0:       pParse->trigStack = trigStackEntry.pNext;
sl@0:       sqlite3AuthContextPop(&sContext);
sl@0: 
sl@0:       sqlite3VdbeResolveLabel(pParse->pVdbe, endTrigger);
sl@0:     }
sl@0:   }
sl@0:   if( piOldColMask ) *piOldColMask |= trigStackEntry.oldColMask;
sl@0:   if( piNewColMask ) *piNewColMask |= trigStackEntry.newColMask;
sl@0:   return 0;
sl@0: }
sl@0: #endif /* !defined(SQLITE_OMIT_TRIGGER) */