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Fix the DROP TABLE command so that it cannot be used to bypass foreign key constraints (if foreign key support is enabled).

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FossilOrigin-Name: 8353808c9e70412fdee31bfda7810e948f1c7485
This commit is contained in:
dan
2009-09-28 14:49:01 +00:00
parent 9277efa3d5
commit d66c83095e
8 changed files with 111 additions and 15 deletions
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58
src/fkey.c
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@@ -587,6 +587,64 @@ static void fkTriggerDelete(sqlite3 *dbMem, Trigger *p){
}
}
/*
** This function is called to generate code that runs when table pTab is
** being dropped from the database. The SrcList passed as the second argument
** to this function contains a single entry guaranteed to resolve to
** table pTab.
**
** Normally, no code is required. However, if either
**
** (a) The table is the parent table of a FK constraint, or
** (b) The table is the child table of a deferred FK constraint and it is
** determined at runtime that there are outstanding deferred FK
** constraint violations in the database,
**
** then the equivalent of "DELETE FROM <tbl>" is executed before dropping
** the table from the database. Triggers are disabled while running this
** DELETE, but foreign key actions are not.
*/
void sqlite3FkDropTable(Parse *pParse, SrcList *pName, Table *pTab){
sqlite3 *db = pParse->db;
if( (db->flags&SQLITE_ForeignKeys) && !IsVirtual(pTab) && !pTab->pSelect ){
int iSkip = 0;
Vdbe *v = sqlite3GetVdbe(pParse);
assert( v ); /* VDBE has already been allocated */
if( sqlite3FkReferences(pTab)==0 ){
/* Search for a deferred foreign key constraint for which this table
** is the child table. If one cannot be found, return without
** generating any VDBE code. If one can be found, then jump over
** the entire DELETE if there are no outstanding deferred constraints
** when this statement is run. */
FKey *p;
for(p=pTab->pFKey; p; p=p->pNextFrom){
if( p->isDeferred ) break;
}
if( !p ) return;
iSkip = sqlite3VdbeMakeLabel(v);
sqlite3VdbeAddOp2(v, OP_FkIfZero, 1, iSkip);
}
pParse->disableTriggers = 1;
sqlite3DeleteFrom(pParse, sqlite3SrcListDup(db, pName, 0), 0);
pParse->disableTriggers = 0;
/* If the DELETE has generated immediate foreign key constraint
** violations, halt the VDBE and return an error at this point, before
** any modifications to the schema are made. This is because statement
** transactions are not able to rollback schema changes. */
sqlite3VdbeAddOp2(v, OP_FkIfZero, 0, sqlite3VdbeCurrentAddr(v)+2);
sqlite3HaltConstraint(
pParse, OE_Abort, "foreign key constraint failed", P4_STATIC
);
if( iSkip ){
sqlite3VdbeResolveLabel(v, iSkip);
}
}
}
/*
** This function is called when inserting, deleting or updating a row of
** table pTab to generate VDBE code to perform foreign key constraint