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sqlite/src/trigger.c
peter.d.reid 60ec914c74 Fix typos in comments. No code changes. 
FossilOrigin-Name: e62aab5e9290503869e1f4d5e0fefd2b4dee0a69
2014-09-06 16:39:46 +00:00

1120 lines
39 KiB
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/*
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation for TRIGGERs
*/
#include "sqliteInt.h"
#ifndef SQLITE_OMIT_TRIGGER
/*
** Delete a linked list of TriggerStep structures.
*/
void sqlite3DeleteTriggerStep(sqlite3 *db, TriggerStep *pTriggerStep){
while( pTriggerStep ){
TriggerStep * pTmp = pTriggerStep;
pTriggerStep = pTriggerStep->pNext;
sqlite3ExprDelete(db, pTmp->pWhere);
sqlite3ExprListDelete(db, pTmp->pExprList);
sqlite3SelectDelete(db, pTmp->pSelect);
sqlite3IdListDelete(db, pTmp->pIdList);
sqlite3DbFree(db, pTmp);
}
}
/*
** Given table pTab, return a list of all the triggers attached to
** the table. The list is connected by Trigger.pNext pointers.
**
** All of the triggers on pTab that are in the same database as pTab
** are already attached to pTab->pTrigger. But there might be additional
** triggers on pTab in the TEMP schema. This routine prepends all
** TEMP triggers on pTab to the beginning of the pTab->pTrigger list
** and returns the combined list.
**
** To state it another way: This routine returns a list of all triggers
** that fire off of pTab. The list will include any TEMP triggers on
** pTab as well as the triggers lised in pTab->pTrigger.
*/
Trigger *sqlite3TriggerList(Parse *pParse, Table *pTab){
Schema * const pTmpSchema = pParse->db->aDb[1].pSchema;
Trigger *pList = 0; /* List of triggers to return */
if( pParse->disableTriggers ){
return 0;
}
if( pTmpSchema!=pTab->pSchema ){
HashElem *p;
assert( sqlite3SchemaMutexHeld(pParse->db, 0, pTmpSchema) );
for(p=sqliteHashFirst(&pTmpSchema->trigHash); p; p=sqliteHashNext(p)){
Trigger *pTrig = (Trigger *)sqliteHashData(p);
if( pTrig->pTabSchema==pTab->pSchema
&& 0==sqlite3StrICmp(pTrig->table, pTab->zName)
){
pTrig->pNext = (pList ? pList : pTab->pTrigger);
pList = pTrig;
}
}
}
return (pList ? pList : pTab->pTrigger);
}
/*
** This is called by the parser when it sees a CREATE TRIGGER statement
** up to the point of the BEGIN before the trigger actions. A Trigger
** structure is generated based on the information available and stored
** in pParse->pNewTrigger. After the trigger actions have been parsed, the
** sqlite3FinishTrigger() function is called to complete the trigger
** construction process.
*/
void sqlite3BeginTrigger(
Parse *pParse, /* The parse context of the CREATE TRIGGER statement */
Token *pName1, /* The name of the trigger */
Token *pName2, /* The name of the trigger */
int tr_tm, /* One of TK_BEFORE, TK_AFTER, TK_INSTEAD */
int op, /* One of TK_INSERT, TK_UPDATE, TK_DELETE */
IdList *pColumns, /* column list if this is an UPDATE OF trigger */
SrcList *pTableName,/* The name of the table/view the trigger applies to */
Expr *pWhen, /* WHEN clause */
int isTemp, /* True if the TEMPORARY keyword is present */
int noErr /* Suppress errors if the trigger already exists */
){
Trigger *pTrigger = 0; /* The new trigger */
Table *pTab; /* Table that the trigger fires off of */
char *zName = 0; /* Name of the trigger */
sqlite3 *db = pParse->db; /* The database connection */
int iDb; /* The database to store the trigger in */
Token *pName; /* The unqualified db name */
DbFixer sFix; /* State vector for the DB fixer */
int iTabDb; /* Index of the database holding pTab */
assert( pName1!=0 ); /* pName1->z might be NULL, but not pName1 itself */
assert( pName2!=0 );
assert( op==TK_INSERT || op==TK_UPDATE || op==TK_DELETE );
assert( op>0 && op<0xff );
if( isTemp ){
/* If TEMP was specified, then the trigger name may not be qualified. */
if( pName2->n>0 ){
sqlite3ErrorMsg(pParse, "temporary trigger may not have qualified name");
goto trigger_cleanup;
}
iDb = 1;
pName = pName1;
}else{
/* Figure out the db that the trigger will be created in */
iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pName);
if( iDb<0 ){
goto trigger_cleanup;
}
}
if( !pTableName || db->mallocFailed ){
goto trigger_cleanup;
}
/* A long-standing parser bug is that this syntax was allowed:
**
** CREATE TRIGGER attached.demo AFTER INSERT ON attached.tab ....
** ^^^^^^^^
**
** To maintain backwards compatibility, ignore the database
** name on pTableName if we are reparsing out of SQLITE_MASTER.
*/
if( db->init.busy && iDb!=1 ){
sqlite3DbFree(db, pTableName->a[0].zDatabase);
pTableName->a[0].zDatabase = 0;
}
/* If the trigger name was unqualified, and the table is a temp table,
** then set iDb to 1 to create the trigger in the temporary database.
** If sqlite3SrcListLookup() returns 0, indicating the table does not
** exist, the error is caught by the block below.
*/
pTab = sqlite3SrcListLookup(pParse, pTableName);
if( db->init.busy==0 && pName2->n==0 && pTab
&& pTab->pSchema==db->aDb[1].pSchema ){
iDb = 1;
}
/* Ensure the table name matches database name and that the table exists */
if( db->mallocFailed ) goto trigger_cleanup;
assert( pTableName->nSrc==1 );
sqlite3FixInit(&sFix, pParse, iDb, "trigger", pName);
if( sqlite3FixSrcList(&sFix, pTableName) ){
goto trigger_cleanup;
}
pTab = sqlite3SrcListLookup(pParse, pTableName);
if( !pTab ){
/* The table does not exist. */
if( db->init.iDb==1 ){
/* Ticket #3810.
** Normally, whenever a table is dropped, all associated triggers are
** dropped too. But if a TEMP trigger is created on a non-TEMP table
** and the table is dropped by a different database connection, the
** trigger is not visible to the database connection that does the
** drop so the trigger cannot be dropped. This results in an
** "orphaned trigger" - a trigger whose associated table is missing.
*/
db->init.orphanTrigger = 1;
}
goto trigger_cleanup;
}
if( IsVirtual(pTab) ){
sqlite3ErrorMsg(pParse, "cannot create triggers on virtual tables");
goto trigger_cleanup;
}
/* Check that the trigger name is not reserved and that no trigger of the
** specified name exists */
zName = sqlite3NameFromToken(db, pName);
if( !zName || SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
goto trigger_cleanup;
}
assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
if( sqlite3HashFind(&(db->aDb[iDb].pSchema->trigHash),zName) ){
if( !noErr ){
sqlite3ErrorMsg(pParse, "trigger %T already exists", pName);
}else{
assert( !db->init.busy );
sqlite3CodeVerifySchema(pParse, iDb);
}
goto trigger_cleanup;
}
/* Do not create a trigger on a system table */
if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 ){
sqlite3ErrorMsg(pParse, "cannot create trigger on system table");
pParse->nErr++;
goto trigger_cleanup;
}
/* INSTEAD of triggers are only for views and views only support INSTEAD
** of triggers.
*/
if( pTab->pSelect && tr_tm!=TK_INSTEAD ){
sqlite3ErrorMsg(pParse, "cannot create %s trigger on view: %S",
(tr_tm == TK_BEFORE)?"BEFORE":"AFTER", pTableName, 0);
goto trigger_cleanup;
}
if( !pTab->pSelect && tr_tm==TK_INSTEAD ){
sqlite3ErrorMsg(pParse, "cannot create INSTEAD OF"
" trigger on table: %S", pTableName, 0);
goto trigger_cleanup;
}
iTabDb = sqlite3SchemaToIndex(db, pTab->pSchema);
#ifndef SQLITE_OMIT_AUTHORIZATION
{
int code = SQLITE_CREATE_TRIGGER;
const char *zDb = db->aDb[iTabDb].zName;
const char *zDbTrig = isTemp ? db->aDb[1].zName : zDb;
if( iTabDb==1 || isTemp ) code = SQLITE_CREATE_TEMP_TRIGGER;
if( sqlite3AuthCheck(pParse, code, zName, pTab->zName, zDbTrig) ){
goto trigger_cleanup;
}
if( sqlite3AuthCheck(pParse, SQLITE_INSERT, SCHEMA_TABLE(iTabDb),0,zDb)){
goto trigger_cleanup;
}
}
#endif
/* INSTEAD OF triggers can only appear on views and BEFORE triggers
** cannot appear on views. So we might as well translate every
** INSTEAD OF trigger into a BEFORE trigger. It simplifies code
** elsewhere.
*/
if (tr_tm == TK_INSTEAD){
tr_tm = TK_BEFORE;
}
/* Build the Trigger object */
pTrigger = (Trigger*)sqlite3DbMallocZero(db, sizeof(Trigger));
if( pTrigger==0 ) goto trigger_cleanup;
pTrigger->zName = zName;
zName = 0;
pTrigger->table = sqlite3DbStrDup(db, pTableName->a[0].zName);
pTrigger->pSchema = db->aDb[iDb].pSchema;
pTrigger->pTabSchema = pTab->pSchema;
pTrigger->op = (u8)op;
pTrigger->tr_tm = tr_tm==TK_BEFORE ? TRIGGER_BEFORE : TRIGGER_AFTER;
pTrigger->pWhen = sqlite3ExprDup(db, pWhen, EXPRDUP_REDUCE);
pTrigger->pColumns = sqlite3IdListDup(db, pColumns);
assert( pParse->pNewTrigger==0 );
pParse->pNewTrigger = pTrigger;
trigger_cleanup:
sqlite3DbFree(db, zName);
sqlite3SrcListDelete(db, pTableName);
sqlite3IdListDelete(db, pColumns);
sqlite3ExprDelete(db, pWhen);
if( !pParse->pNewTrigger ){
sqlite3DeleteTrigger(db, pTrigger);
}else{
assert( pParse->pNewTrigger==pTrigger );
}
}
/*
** This routine is called after all of the trigger actions have been parsed
** in order to complete the process of building the trigger.
*/
void sqlite3FinishTrigger(
Parse *pParse, /* Parser context */
TriggerStep *pStepList, /* The triggered program */
Token *pAll /* Token that describes the complete CREATE TRIGGER */
){
Trigger *pTrig = pParse->pNewTrigger; /* Trigger being finished */
char *zName; /* Name of trigger */
sqlite3 *db = pParse->db; /* The database */
DbFixer sFix; /* Fixer object */
int iDb; /* Database containing the trigger */
Token nameToken; /* Trigger name for error reporting */
pParse->pNewTrigger = 0;
if( NEVER(pParse->nErr) || !pTrig ) goto triggerfinish_cleanup;
zName = pTrig->zName;
iDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema);
pTrig->step_list = pStepList;
while( pStepList ){
pStepList->pTrig = pTrig;
pStepList = pStepList->pNext;
}
nameToken.z = pTrig->zName;
nameToken.n = sqlite3Strlen30(nameToken.z);
sqlite3FixInit(&sFix, pParse, iDb, "trigger", &nameToken);
if( sqlite3FixTriggerStep(&sFix, pTrig->step_list)
|| sqlite3FixExpr(&sFix, pTrig->pWhen)
){
goto triggerfinish_cleanup;
}
/* if we are not initializing,
** build the sqlite_master entry
*/
if( !db->init.busy ){
Vdbe *v;
char *z;
/* Make an entry in the sqlite_master table */
v = sqlite3GetVdbe(pParse);
if( v==0 ) goto triggerfinish_cleanup;
sqlite3BeginWriteOperation(pParse, 0, iDb);
z = sqlite3DbStrNDup(db, (char*)pAll->z, pAll->n);
sqlite3NestedParse(pParse,
"INSERT INTO %Q.%s VALUES('trigger',%Q,%Q,0,'CREATE TRIGGER %q')",
db->aDb[iDb].zName, SCHEMA_TABLE(iDb), zName,
pTrig->table, z);
sqlite3DbFree(db, z);
sqlite3ChangeCookie(pParse, iDb);
sqlite3VdbeAddParseSchemaOp(v, iDb,
sqlite3MPrintf(db, "type='trigger' AND name='%q'", zName));
}
if( db->init.busy ){
Trigger *pLink = pTrig;
Hash *pHash = &db->aDb[iDb].pSchema->trigHash;
assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
pTrig = sqlite3HashInsert(pHash, zName, pTrig);
if( pTrig ){
db->mallocFailed = 1;
}else if( pLink->pSchema==pLink->pTabSchema ){
Table *pTab;
pTab = sqlite3HashFind(&pLink->pTabSchema->tblHash, pLink->table);
assert( pTab!=0 );
pLink->pNext = pTab->pTrigger;
pTab->pTrigger = pLink;
}
}
triggerfinish_cleanup:
sqlite3DeleteTrigger(db, pTrig);
assert( !pParse->pNewTrigger );
sqlite3DeleteTriggerStep(db, pStepList);
}
/*
** Turn a SELECT statement (that the pSelect parameter points to) into
** a trigger step. Return a pointer to a TriggerStep structure.
**
** The parser calls this routine when it finds a SELECT statement in
** body of a TRIGGER.
*/
TriggerStep *sqlite3TriggerSelectStep(sqlite3 *db, Select *pSelect){
TriggerStep *pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep));
if( pTriggerStep==0 ) {
sqlite3SelectDelete(db, pSelect);
return 0;
}
pTriggerStep->op = TK_SELECT;
pTriggerStep->pSelect = pSelect;
pTriggerStep->orconf = OE_Default;
return pTriggerStep;
}
/*
** Allocate space to hold a new trigger step. The allocated space
** holds both the TriggerStep object and the TriggerStep.target.z string.
**
** If an OOM error occurs, NULL is returned and db->mallocFailed is set.
*/
static TriggerStep *triggerStepAllocate(
sqlite3 *db, /* Database connection */
u8 op, /* Trigger opcode */
Token *pName /* The target name */
){
TriggerStep *pTriggerStep;
pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep) + pName->n);
if( pTriggerStep ){
char *z = (char*)&pTriggerStep[1];
memcpy(z, pName->z, pName->n);
pTriggerStep->target.z = z;
pTriggerStep->target.n = pName->n;
pTriggerStep->op = op;
}
return pTriggerStep;
}
/*
** Build a trigger step out of an INSERT statement. Return a pointer
** to the new trigger step.
**
** The parser calls this routine when it sees an INSERT inside the
** body of a trigger.
*/
TriggerStep *sqlite3TriggerInsertStep(
sqlite3 *db, /* The database connection */
Token *pTableName, /* Name of the table into which we insert */
IdList *pColumn, /* List of columns in pTableName to insert into */
Select *pSelect, /* A SELECT statement that supplies values */
u8 orconf /* The conflict algorithm (OE_Abort, OE_Replace, etc.) */
){
TriggerStep *pTriggerStep;
assert(pSelect != 0 || db->mallocFailed);
pTriggerStep = triggerStepAllocate(db, TK_INSERT, pTableName);
if( pTriggerStep ){
pTriggerStep->pSelect = sqlite3SelectDup(db, pSelect, EXPRDUP_REDUCE);
pTriggerStep->pIdList = pColumn;
pTriggerStep->orconf = orconf;
}else{
sqlite3IdListDelete(db, pColumn);
}
sqlite3SelectDelete(db, pSelect);
return pTriggerStep;
}
/*
** Construct a trigger step that implements an UPDATE statement and return
** a pointer to that trigger step. The parser calls this routine when it
** sees an UPDATE statement inside the body of a CREATE TRIGGER.
*/
TriggerStep *sqlite3TriggerUpdateStep(
sqlite3 *db, /* The database connection */
Token *pTableName, /* Name of the table to be updated */
ExprList *pEList, /* The SET clause: list of column and new values */
Expr *pWhere, /* The WHERE clause */
u8 orconf /* The conflict algorithm. (OE_Abort, OE_Ignore, etc) */
){
TriggerStep *pTriggerStep;
pTriggerStep = triggerStepAllocate(db, TK_UPDATE, pTableName);
if( pTriggerStep ){
pTriggerStep->pExprList = sqlite3ExprListDup(db, pEList, EXPRDUP_REDUCE);
pTriggerStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
pTriggerStep->orconf = orconf;
}
sqlite3ExprListDelete(db, pEList);
sqlite3ExprDelete(db, pWhere);
return pTriggerStep;
}
/*
** Construct a trigger step that implements a DELETE statement and return
** a pointer to that trigger step. The parser calls this routine when it
** sees a DELETE statement inside the body of a CREATE TRIGGER.
*/
TriggerStep *sqlite3TriggerDeleteStep(
sqlite3 *db, /* Database connection */
Token *pTableName, /* The table from which rows are deleted */
Expr *pWhere /* The WHERE clause */
){
TriggerStep *pTriggerStep;
pTriggerStep = triggerStepAllocate(db, TK_DELETE, pTableName);
if( pTriggerStep ){
pTriggerStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
pTriggerStep->orconf = OE_Default;
}
sqlite3ExprDelete(db, pWhere);
return pTriggerStep;
}
/*
** Recursively delete a Trigger structure
*/
void sqlite3DeleteTrigger(sqlite3 *db, Trigger *pTrigger){
if( pTrigger==0 ) return;
sqlite3DeleteTriggerStep(db, pTrigger->step_list);
sqlite3DbFree(db, pTrigger->zName);
sqlite3DbFree(db, pTrigger->table);
sqlite3ExprDelete(db, pTrigger->pWhen);
sqlite3IdListDelete(db, pTrigger->pColumns);
sqlite3DbFree(db, pTrigger);
}
/*
** This function is called to drop a trigger from the database schema.
**
** This may be called directly from the parser and therefore identifies
** the trigger by name. The sqlite3DropTriggerPtr() routine does the
** same job as this routine except it takes a pointer to the trigger
** instead of the trigger name.
**/
void sqlite3DropTrigger(Parse *pParse, SrcList *pName, int noErr){
Trigger *pTrigger = 0;
int i;
const char *zDb;
const char *zName;
sqlite3 *db = pParse->db;
if( db->mallocFailed ) goto drop_trigger_cleanup;
if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
goto drop_trigger_cleanup;
}
assert( pName->nSrc==1 );
zDb = pName->a[0].zDatabase;
zName = pName->a[0].zName;
assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
for(i=OMIT_TEMPDB; i<db->nDb; i++){
int j = (i<2) ? i^1 : i; /* Search TEMP before MAIN */
if( zDb && sqlite3StrICmp(db->aDb[j].zName, zDb) ) continue;
assert( sqlite3SchemaMutexHeld(db, j, 0) );
pTrigger = sqlite3HashFind(&(db->aDb[j].pSchema->trigHash), zName);
if( pTrigger ) break;
}
if( !pTrigger ){
if( !noErr ){
sqlite3ErrorMsg(pParse, "no such trigger: %S", pName, 0);
}else{
sqlite3CodeVerifyNamedSchema(pParse, zDb);
}
pParse->checkSchema = 1;
goto drop_trigger_cleanup;
}
sqlite3DropTriggerPtr(pParse, pTrigger);
drop_trigger_cleanup:
sqlite3SrcListDelete(db, pName);
}
/*
** Return a pointer to the Table structure for the table that a trigger
** is set on.
*/
static Table *tableOfTrigger(Trigger *pTrigger){
return sqlite3HashFind(&pTrigger->pTabSchema->tblHash, pTrigger->table);
}
/*
** Drop a trigger given a pointer to that trigger.
*/
void sqlite3DropTriggerPtr(Parse *pParse, Trigger *pTrigger){
Table *pTable;
Vdbe *v;
sqlite3 *db = pParse->db;
int iDb;
iDb = sqlite3SchemaToIndex(pParse->db, pTrigger->pSchema);
assert( iDb>=0 && iDb<db->nDb );
pTable = tableOfTrigger(pTrigger);
assert( pTable );
assert( pTable->pSchema==pTrigger->pSchema || iDb==1 );
#ifndef SQLITE_OMIT_AUTHORIZATION
{
int code = SQLITE_DROP_TRIGGER;
const char *zDb = db->aDb[iDb].zName;
const char *zTab = SCHEMA_TABLE(iDb);
if( iDb==1 ) code = SQLITE_DROP_TEMP_TRIGGER;
if( sqlite3AuthCheck(pParse, code, pTrigger->zName, pTable->zName, zDb) ||
sqlite3AuthCheck(pParse, SQLITE_DELETE, zTab, 0, zDb) ){
return;
}
}
#endif
/* Generate code to destroy the database record of the trigger.
*/
assert( pTable!=0 );
if( (v = sqlite3GetVdbe(pParse))!=0 ){
int base;
static const int iLn = VDBE_OFFSET_LINENO(2);
static const VdbeOpList dropTrigger[] = {
{ OP_Rewind, 0, ADDR(9), 0},
{ OP_String8, 0, 1, 0}, /* 1 */
{ OP_Column, 0, 1, 2},
{ OP_Ne, 2, ADDR(8), 1},
{ OP_String8, 0, 1, 0}, /* 4: "trigger" */
{ OP_Column, 0, 0, 2},
{ OP_Ne, 2, ADDR(8), 1},
{ OP_Delete, 0, 0, 0},
{ OP_Next, 0, ADDR(1), 0}, /* 8 */
};
sqlite3BeginWriteOperation(pParse, 0, iDb);
sqlite3OpenMasterTable(pParse, iDb);
base = sqlite3VdbeAddOpList(v, ArraySize(dropTrigger), dropTrigger, iLn);
sqlite3VdbeChangeP4(v, base+1, pTrigger->zName, P4_TRANSIENT);
sqlite3VdbeChangeP4(v, base+4, "trigger", P4_STATIC);
sqlite3ChangeCookie(pParse, iDb);
sqlite3VdbeAddOp2(v, OP_Close, 0, 0);
sqlite3VdbeAddOp4(v, OP_DropTrigger, iDb, 0, 0, pTrigger->zName, 0);
if( pParse->nMem<3 ){
pParse->nMem = 3;
}
}
}
/*
** Remove a trigger from the hash tables of the sqlite* pointer.
*/
void sqlite3UnlinkAndDeleteTrigger(sqlite3 *db, int iDb, const char *zName){
Trigger *pTrigger;
Hash *pHash;
assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
pHash = &(db->aDb[iDb].pSchema->trigHash);
pTrigger = sqlite3HashInsert(pHash, zName, 0);
if( ALWAYS(pTrigger) ){
if( pTrigger->pSchema==pTrigger->pTabSchema ){
Table *pTab = tableOfTrigger(pTrigger);
Trigger **pp;
for(pp=&pTab->pTrigger; *pp!=pTrigger; pp=&((*pp)->pNext));
*pp = (*pp)->pNext;
}
sqlite3DeleteTrigger(db, pTrigger);
db->flags |= SQLITE_InternChanges;
}
}
/*
** pEList is the SET clause of an UPDATE statement. Each entry
** in pEList is of the format <id>=<expr>. If any of the entries
** in pEList have an <id> which matches an identifier in pIdList,
** then return TRUE. If pIdList==NULL, then it is considered a
** wildcard that matches anything. Likewise if pEList==NULL then
** it matches anything so always return true. Return false only
** if there is no match.
*/
static int checkColumnOverlap(IdList *pIdList, ExprList *pEList){
int e;
if( pIdList==0 || NEVER(pEList==0) ) return 1;
for(e=0; e<pEList->nExpr; e++){
if( sqlite3IdListIndex(pIdList, pEList->a[e].zName)>=0 ) return 1;
}
return 0;
}
/*
** Return a list of all triggers on table pTab if there exists at least
** one trigger that must be fired when an operation of type 'op' is
** performed on the table, and, if that operation is an UPDATE, if at
** least one of the columns in pChanges is being modified.
*/
Trigger *sqlite3TriggersExist(
Parse *pParse, /* Parse context */
Table *pTab, /* The table the contains the triggers */
int op, /* one of TK_DELETE, TK_INSERT, TK_UPDATE */
ExprList *pChanges, /* Columns that change in an UPDATE statement */
int *pMask /* OUT: Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
){
int mask = 0;
Trigger *pList = 0;
Trigger *p;
if( (pParse->db->flags & SQLITE_EnableTrigger)!=0 ){
pList = sqlite3TriggerList(pParse, pTab);
}
assert( pList==0 || IsVirtual(pTab)==0 );
for(p=pList; p; p=p->pNext){
if( p->op==op && checkColumnOverlap(p->pColumns, pChanges) ){
mask |= p->tr_tm;
}
}
if( pMask ){
*pMask = mask;
}
return (mask ? pList : 0);
}
/*
** Convert the pStep->target token into a SrcList and return a pointer
** to that SrcList.
**
** This routine adds a specific database name, if needed, to the target when
** forming the SrcList. This prevents a trigger in one database from
** referring to a target in another database. An exception is when the
** trigger is in TEMP in which case it can refer to any other database it
** wants.
*/
static SrcList *targetSrcList(
Parse *pParse, /* The parsing context */
TriggerStep *pStep /* The trigger containing the target token */
){
int iDb; /* Index of the database to use */
SrcList *pSrc; /* SrcList to be returned */
pSrc = sqlite3SrcListAppend(pParse->db, 0, &pStep->target, 0);
if( pSrc ){
assert( pSrc->nSrc>0 );
assert( pSrc->a!=0 );
iDb = sqlite3SchemaToIndex(pParse->db, pStep->pTrig->pSchema);
if( iDb==0 || iDb>=2 ){
sqlite3 *db = pParse->db;
assert( iDb<pParse->db->nDb );
pSrc->a[pSrc->nSrc-1].zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zName);
}
}
return pSrc;
}
/*
** Generate VDBE code for the statements inside the body of a single
** trigger.
*/
static int codeTriggerProgram(
Parse *pParse, /* The parser context */
TriggerStep *pStepList, /* List of statements inside the trigger body */
int orconf /* Conflict algorithm. (OE_Abort, etc) */
){
TriggerStep *pStep;
Vdbe *v = pParse->pVdbe;
sqlite3 *db = pParse->db;
assert( pParse->pTriggerTab && pParse->pToplevel );
assert( pStepList );
assert( v!=0 );
for(pStep=pStepList; pStep; pStep=pStep->pNext){
/* Figure out the ON CONFLICT policy that will be used for this step
** of the trigger program. If the statement that caused this trigger
** to fire had an explicit ON CONFLICT, then use it. Otherwise, use
** the ON CONFLICT policy that was specified as part of the trigger
** step statement. Example:
**
** CREATE TRIGGER AFTER INSERT ON t1 BEGIN;
** INSERT OR REPLACE INTO t2 VALUES(new.a, new.b);
** END;
**
** INSERT INTO t1 ... ; -- insert into t2 uses REPLACE policy
** INSERT OR IGNORE INTO t1 ... ; -- insert into t2 uses IGNORE policy
*/
pParse->eOrconf = (orconf==OE_Default)?pStep->orconf:(u8)orconf;
assert( pParse->okConstFactor==0 );
switch( pStep->op ){
case TK_UPDATE: {
sqlite3Update(pParse,
targetSrcList(pParse, pStep),
sqlite3ExprListDup(db, pStep->pExprList, 0),
sqlite3ExprDup(db, pStep->pWhere, 0),
pParse->eOrconf
);
break;
}
case TK_INSERT: {
sqlite3Insert(pParse,
targetSrcList(pParse, pStep),
sqlite3SelectDup(db, pStep->pSelect, 0),
sqlite3IdListDup(db, pStep->pIdList),
pParse->eOrconf
);
break;
}
case TK_DELETE: {
sqlite3DeleteFrom(pParse,
targetSrcList(pParse, pStep),
sqlite3ExprDup(db, pStep->pWhere, 0)
);
break;
}
default: assert( pStep->op==TK_SELECT ); {
SelectDest sDest;
Select *pSelect = sqlite3SelectDup(db, pStep->pSelect, 0);
sqlite3SelectDestInit(&sDest, SRT_Discard, 0);
sqlite3Select(pParse, pSelect, &sDest);
sqlite3SelectDelete(db, pSelect);
break;
}
}
if( pStep->op!=TK_SELECT ){
sqlite3VdbeAddOp0(v, OP_ResetCount);
}
}
return 0;
}
#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
/*
** This function is used to add VdbeComment() annotations to a VDBE
** program. It is not used in production code, only for debugging.
*/
static const char *onErrorText(int onError){
switch( onError ){
case OE_Abort: return "abort";
case OE_Rollback: return "rollback";
case OE_Fail: return "fail";
case OE_Replace: return "replace";
case OE_Ignore: return "ignore";
case OE_Default: return "default";
}
return "n/a";
}
#endif
/*
** Parse context structure pFrom has just been used to create a sub-vdbe
** (trigger program). If an error has occurred, transfer error information
** from pFrom to pTo.
*/
static void transferParseError(Parse *pTo, Parse *pFrom){
assert( pFrom->zErrMsg==0 || pFrom->nErr );
assert( pTo->zErrMsg==0 || pTo->nErr );
if( pTo->nErr==0 ){
pTo->zErrMsg = pFrom->zErrMsg;
pTo->nErr = pFrom->nErr;
}else{
sqlite3DbFree(pFrom->db, pFrom->zErrMsg);
}
}
/*
** Create and populate a new TriggerPrg object with a sub-program
** implementing trigger pTrigger with ON CONFLICT policy orconf.
*/
static TriggerPrg *codeRowTrigger(
Parse *pParse, /* Current parse context */
Trigger *pTrigger, /* Trigger to code */
Table *pTab, /* The table pTrigger is attached to */
int orconf /* ON CONFLICT policy to code trigger program with */
){
Parse *pTop = sqlite3ParseToplevel(pParse);
sqlite3 *db = pParse->db; /* Database handle */
TriggerPrg *pPrg; /* Value to return */
Expr *pWhen = 0; /* Duplicate of trigger WHEN expression */
Vdbe *v; /* Temporary VM */
NameContext sNC; /* Name context for sub-vdbe */
SubProgram *pProgram = 0; /* Sub-vdbe for trigger program */
Parse *pSubParse; /* Parse context for sub-vdbe */
int iEndTrigger = 0; /* Label to jump to if WHEN is false */
assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
assert( pTop->pVdbe );
/* Allocate the TriggerPrg and SubProgram objects. To ensure that they
** are freed if an error occurs, link them into the Parse.pTriggerPrg
** list of the top-level Parse object sooner rather than later. */
pPrg = sqlite3DbMallocZero(db, sizeof(TriggerPrg));
if( !pPrg ) return 0;
pPrg->pNext = pTop->pTriggerPrg;
pTop->pTriggerPrg = pPrg;
pPrg->pProgram = pProgram = sqlite3DbMallocZero(db, sizeof(SubProgram));
if( !pProgram ) return 0;
sqlite3VdbeLinkSubProgram(pTop->pVdbe, pProgram);
pPrg->pTrigger = pTrigger;
pPrg->orconf = orconf;
pPrg->aColmask[0] = 0xffffffff;
pPrg->aColmask[1] = 0xffffffff;
/* Allocate and populate a new Parse context to use for coding the
** trigger sub-program. */
pSubParse = sqlite3StackAllocZero(db, sizeof(Parse));
if( !pSubParse ) return 0;
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pSubParse;
pSubParse->db = db;
pSubParse->pTriggerTab = pTab;
pSubParse->pToplevel = pTop;
pSubParse->zAuthContext = pTrigger->zName;
pSubParse->eTriggerOp = pTrigger->op;
pSubParse->nQueryLoop = pParse->nQueryLoop;
v = sqlite3GetVdbe(pSubParse);
if( v ){
VdbeComment((v, "Start: %s.%s (%s %s%s%s ON %s)",
pTrigger->zName, onErrorText(orconf),
(pTrigger->tr_tm==TRIGGER_BEFORE ? "BEFORE" : "AFTER"),
(pTrigger->op==TK_UPDATE ? "UPDATE" : ""),
(pTrigger->op==TK_INSERT ? "INSERT" : ""),
(pTrigger->op==TK_DELETE ? "DELETE" : ""),
pTab->zName
));
#ifndef SQLITE_OMIT_TRACE
sqlite3VdbeChangeP4(v, -1,
sqlite3MPrintf(db, "-- TRIGGER %s", pTrigger->zName), P4_DYNAMIC
);
#endif
/* If one was specified, code the WHEN clause. If it evaluates to false
** (or NULL) the sub-vdbe is immediately halted by jumping to the
** OP_Halt inserted at the end of the program. */
if( pTrigger->pWhen ){
pWhen = sqlite3ExprDup(db, pTrigger->pWhen, 0);
if( SQLITE_OK==sqlite3ResolveExprNames(&sNC, pWhen)
&& db->mallocFailed==0
){
iEndTrigger = sqlite3VdbeMakeLabel(v);
sqlite3ExprIfFalse(pSubParse, pWhen, iEndTrigger, SQLITE_JUMPIFNULL);
}
sqlite3ExprDelete(db, pWhen);
}
/* Code the trigger program into the sub-vdbe. */
codeTriggerProgram(pSubParse, pTrigger->step_list, orconf);
/* Insert an OP_Halt at the end of the sub-program. */
if( iEndTrigger ){
sqlite3VdbeResolveLabel(v, iEndTrigger);
}
sqlite3VdbeAddOp0(v, OP_Halt);
VdbeComment((v, "End: %s.%s", pTrigger->zName, onErrorText(orconf)));
transferParseError(pParse, pSubParse);
if( db->mallocFailed==0 ){
pProgram->aOp = sqlite3VdbeTakeOpArray(v, &pProgram->nOp, &pTop->nMaxArg);
}
pProgram->nMem = pSubParse->nMem;
pProgram->nCsr = pSubParse->nTab;
pProgram->nOnce = pSubParse->nOnce;
pProgram->token = (void *)pTrigger;
pPrg->aColmask[0] = pSubParse->oldmask;
pPrg->aColmask[1] = pSubParse->newmask;
sqlite3VdbeDelete(v);
}
assert( !pSubParse->pAinc && !pSubParse->pZombieTab );
assert( !pSubParse->pTriggerPrg && !pSubParse->nMaxArg );
sqlite3ParserReset(pSubParse);
sqlite3StackFree(db, pSubParse);
return pPrg;
}
/*
** Return a pointer to a TriggerPrg object containing the sub-program for
** trigger pTrigger with default ON CONFLICT algorithm orconf. If no such
** TriggerPrg object exists, a new object is allocated and populated before
** being returned.
*/
static TriggerPrg *getRowTrigger(
Parse *pParse, /* Current parse context */
Trigger *pTrigger, /* Trigger to code */
Table *pTab, /* The table trigger pTrigger is attached to */
int orconf /* ON CONFLICT algorithm. */
){
Parse *pRoot = sqlite3ParseToplevel(pParse);
TriggerPrg *pPrg;
assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
/* It may be that this trigger has already been coded (or is in the
** process of being coded). If this is the case, then an entry with
** a matching TriggerPrg.pTrigger field will be present somewhere
** in the Parse.pTriggerPrg list. Search for such an entry. */
for(pPrg=pRoot->pTriggerPrg;
pPrg && (pPrg->pTrigger!=pTrigger || pPrg->orconf!=orconf);
pPrg=pPrg->pNext
);
/* If an existing TriggerPrg could not be located, create a new one. */
if( !pPrg ){
pPrg = codeRowTrigger(pParse, pTrigger, pTab, orconf);
}
return pPrg;
}
/*
** Generate code for the trigger program associated with trigger p on
** table pTab. The reg, orconf and ignoreJump parameters passed to this
** function are the same as those described in the header function for
** sqlite3CodeRowTrigger()
*/
void sqlite3CodeRowTriggerDirect(
Parse *pParse, /* Parse context */
Trigger *p, /* Trigger to code */
Table *pTab, /* The table to code triggers from */
int reg, /* Reg array containing OLD.* and NEW.* values */
int orconf, /* ON CONFLICT policy */
int ignoreJump /* Instruction to jump to for RAISE(IGNORE) */
){
Vdbe *v = sqlite3GetVdbe(pParse); /* Main VM */
TriggerPrg *pPrg;
pPrg = getRowTrigger(pParse, p, pTab, orconf);
assert( pPrg || pParse->nErr || pParse->db->mallocFailed );
/* Code the OP_Program opcode in the parent VDBE. P4 of the OP_Program
** is a pointer to the sub-vdbe containing the trigger program. */
if( pPrg ){
int bRecursive = (p->zName && 0==(pParse->db->flags&SQLITE_RecTriggers));
sqlite3VdbeAddOp3(v, OP_Program, reg, ignoreJump, ++pParse->nMem);
sqlite3VdbeChangeP4(v, -1, (const char *)pPrg->pProgram, P4_SUBPROGRAM);
VdbeComment(
(v, "Call: %s.%s", (p->zName?p->zName:"fkey"), onErrorText(orconf)));
/* Set the P5 operand of the OP_Program instruction to non-zero if
** recursive invocation of this trigger program is disallowed. Recursive
** invocation is disallowed if (a) the sub-program is really a trigger,
** not a foreign key action, and (b) the flag to enable recursive triggers
** is clear. */
sqlite3VdbeChangeP5(v, (u8)bRecursive);
}
}
/*
** This is called to code the required FOR EACH ROW triggers for an operation
** on table pTab. The operation to code triggers for (INSERT, UPDATE or DELETE)
** is given by the op parameter. The tr_tm parameter determines whether the
** BEFORE or AFTER triggers are coded. If the operation is an UPDATE, then
** parameter pChanges is passed the list of columns being modified.
**
** If there are no triggers that fire at the specified time for the specified
** operation on pTab, this function is a no-op.
**
** The reg argument is the address of the first in an array of registers
** that contain the values substituted for the new.* and old.* references
** in the trigger program. If N is the number of columns in table pTab
** (a copy of pTab->nCol), then registers are populated as follows:
**
** Register Contains
** ------------------------------------------------------
** reg+0 OLD.rowid
** reg+1 OLD.* value of left-most column of pTab
** ... ...
** reg+N OLD.* value of right-most column of pTab
** reg+N+1 NEW.rowid
** reg+N+2 OLD.* value of left-most column of pTab
** ... ...
** reg+N+N+1 NEW.* value of right-most column of pTab
**
** For ON DELETE triggers, the registers containing the NEW.* values will
** never be accessed by the trigger program, so they are not allocated or
** populated by the caller (there is no data to populate them with anyway).
** Similarly, for ON INSERT triggers the values stored in the OLD.* registers
** are never accessed, and so are not allocated by the caller. So, for an
** ON INSERT trigger, the value passed to this function as parameter reg
** is not a readable register, although registers (reg+N) through
** (reg+N+N+1) are.
**
** Parameter orconf is the default conflict resolution algorithm for the
** trigger program to use (REPLACE, IGNORE etc.). Parameter ignoreJump
** is the instruction that control should jump to if a trigger program
** raises an IGNORE exception.
*/
void sqlite3CodeRowTrigger(
Parse *pParse, /* Parse context */
Trigger *pTrigger, /* List of triggers on table pTab */
int op, /* One of TK_UPDATE, TK_INSERT, TK_DELETE */
ExprList *pChanges, /* Changes list for any UPDATE OF triggers */
int tr_tm, /* One of TRIGGER_BEFORE, TRIGGER_AFTER */
Table *pTab, /* The table to code triggers from */
int reg, /* The first in an array of registers (see above) */
int orconf, /* ON CONFLICT policy */
int ignoreJump /* Instruction to jump to for RAISE(IGNORE) */
){
Trigger *p; /* Used to iterate through pTrigger list */
assert( op==TK_UPDATE || op==TK_INSERT || op==TK_DELETE );
assert( tr_tm==TRIGGER_BEFORE || tr_tm==TRIGGER_AFTER );
assert( (op==TK_UPDATE)==(pChanges!=0) );
for(p=pTrigger; p; p=p->pNext){
/* Sanity checking: The schema for the trigger and for the table are
** always defined. The trigger must be in the same schema as the table
** or else it must be a TEMP trigger. */
assert( p->pSchema!=0 );
assert( p->pTabSchema!=0 );
assert( p->pSchema==p->pTabSchema
|| p->pSchema==pParse->db->aDb[1].pSchema );
/* Determine whether we should code this trigger */
if( p->op==op
&& p->tr_tm==tr_tm
&& checkColumnOverlap(p->pColumns, pChanges)
){
sqlite3CodeRowTriggerDirect(pParse, p, pTab, reg, orconf, ignoreJump);
}
}
}
/*
** Triggers may access values stored in the old.* or new.* pseudo-table.
** This function returns a 32-bit bitmask indicating which columns of the
** old.* or new.* tables actually are used by triggers. This information
** may be used by the caller, for example, to avoid having to load the entire
** old.* record into memory when executing an UPDATE or DELETE command.
**
** Bit 0 of the returned mask is set if the left-most column of the
** table may be accessed using an [old|new].<col> reference. Bit 1 is set if
** the second leftmost column value is required, and so on. If there
** are more than 32 columns in the table, and at least one of the columns
** with an index greater than 32 may be accessed, 0xffffffff is returned.
**
** It is not possible to determine if the old.rowid or new.rowid column is
** accessed by triggers. The caller must always assume that it is.
**
** Parameter isNew must be either 1 or 0. If it is 0, then the mask returned
** applies to the old.* table. If 1, the new.* table.
**
** Parameter tr_tm must be a mask with one or both of the TRIGGER_BEFORE
** and TRIGGER_AFTER bits set. Values accessed by BEFORE triggers are only
** included in the returned mask if the TRIGGER_BEFORE bit is set in the
** tr_tm parameter. Similarly, values accessed by AFTER triggers are only
** included in the returned mask if the TRIGGER_AFTER bit is set in tr_tm.
*/
u32 sqlite3TriggerColmask(
Parse *pParse, /* Parse context */
Trigger *pTrigger, /* List of triggers on table pTab */
ExprList *pChanges, /* Changes list for any UPDATE OF triggers */
int isNew, /* 1 for new.* ref mask, 0 for old.* ref mask */
int tr_tm, /* Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
Table *pTab, /* The table to code triggers from */
int orconf /* Default ON CONFLICT policy for trigger steps */
){
const int op = pChanges ? TK_UPDATE : TK_DELETE;
u32 mask = 0;
Trigger *p;
assert( isNew==1 || isNew==0 );
for(p=pTrigger; p; p=p->pNext){
if( p->op==op && (tr_tm&p->tr_tm)
&& checkColumnOverlap(p->pColumns,pChanges)
){
TriggerPrg *pPrg;
pPrg = getRowTrigger(pParse, p, pTab, orconf);
if( pPrg ){
mask |= pPrg->aColmask[isNew];
}
}
}
return mask;
}
#endif /* !defined(SQLITE_OMIT_TRIGGER) */
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