xref: /PHP-5.3/ext/sqlite/libsqlite/src/trigger.c (revision e563b4ea)
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 */
sqliteDeleteTriggerStep(TriggerStep * pTriggerStep)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 */
sqliteBeginTrigger(Parse * pParse,Token * pName,int tr_tm,int op,IdList * pColumns,SrcList * pTableName,int foreach,Expr * pWhen,int isTemp)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 */
sqliteFinishTrigger(Parse * pParse,TriggerStep * pStepList,Token * pAll)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 */
sqlitePersistTriggerStep(TriggerStep * p)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 */
sqliteTriggerSelectStep(Select * pSelect)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 */
sqliteTriggerInsertStep(Token * pTableName,IdList * pColumn,ExprList * pEList,Select * pSelect,int orconf)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 */
sqliteTriggerUpdateStep(Token * pTableName,ExprList * pEList,Expr * pWhere,int orconf)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 */
sqliteTriggerDeleteStep(Token * pTableName,Expr * pWhere)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 */
sqliteDeleteTrigger(Trigger * pTrigger)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  */
sqliteDropTrigger(Parse * pParse,SrcList * pName)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 */
sqliteDropTriggerPtr(Parse * pParse,Trigger * pTrigger,int nested)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 */
checkColumnOverLap(IdList * pIdList,ExprList * pEList)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  */
sqliteTriggersExist(Parse * pParse,Trigger * pTrigger,int op,int tr_tm,int foreach,ExprList * pChanges)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 */
targetSrcList(Parse * pParse,TriggerStep * pStep)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 */
codeTriggerProgram(Parse * pParse,TriggerStep * pStepList,int orconfin)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 */
sqliteCodeRowTrigger(Parse * pParse,int op,ExprList * pChanges,int tr_tm,Table * pTab,int newIdx,int oldIdx,int orconf,int ignoreJump)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 }
765