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

FossilOrigin-Name: 8353808c9e70412fdee31bfda7810e948f1c7485

manifest

@@ -1,5 +1,5 @@
-C Fix\ssome\sforeign\skey\sconstraint\srelated\sproblems\sthat\soccur\swhen\sa\srow\srefers\sto\sitself.
-D 2009-09-28T11:54:22
+C Fix\sthe\sDROP\sTABLE\scommand\sso\sthat\sit\scannot\sbe\sused\sto\sbypass\sforeign\skey\sconstraints\s(if\sforeign\skey\ssupport\sis\senabled).
+D 2009-09-28T14:49:02
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 4ca3f1dd6efa2075bcb27f4dc43eef749877740d
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -109,14 +109,14 @@ F src/btmutex.c 0f43a75bb5b8147b386e8e1c3e71ba734e3863b7
 F src/btree.c 9c425425784c5d569bc0309c22251698ba906451
 F src/btree.h 577448a890c2ab9b21e6ab74f073526184bceebe
 F src/btreeInt.h 1c86297e69380f6577e7ae67452597dd8d5c2705
-F src/build.c c6c8d4ce8c0a464bb25d0c3bfdb27834ad16d902
+F src/build.c 1988dad2799d0421cd9fb6431fd3a1667115522e
 F src/callback.c 10d237171472865f58fb07d515737238c9e06688
 F src/complete.c 5ad5c6cd4548211867c204c41a126d73a9fbcea0
 F src/date.c 657ff12ca0f1195b531561afacbb38b772d16638
 F src/delete.c 2a3d6fc0861b2f8dbd9feb7847b390267b281c60
 F src/expr.c c7f3f718bd5c392344ec8694a41c1824f30cf375
 F src/fault.c dc88c821842157460750d2d61a8a8b4197d047ff
-F src/fkey.c 5bbe13f5d9ffba1a21ec16fdc3ac1c0964a28597
+F src/fkey.c 8c5deb1775c5051327ebe9fc2fc54ef57890c83d
 F src/func.c e536218d193b8d326aab91120bc4c6f28aa2b606
 F src/global.c 271952d199a8cc59d4ce840b3bbbfd2f30c8ba32
 F src/hash.c ebcaa921ffd9d86f7ea5ae16a0a29d1c871130a7
@@ -164,7 +164,7 @@ F src/select.c 1d0a13137532321b4364f964e46f057d271691e3
 F src/shell.c d6e64471aafb81f355262533393169a70529847a
 F src/sqlite.h.in 5af8181f815831a8672c3834c60e6b4418448bcc
 F src/sqlite3ext.h 1db7d63ab5de4b3e6b83dd03d1a4e64fef6d2a17
-F src/sqliteInt.h 21510d10a6794c633e044e8396acb7899396a9e8
+F src/sqliteInt.h 284a65c29bc4f2a77aa45994285fb55f7de537b9
 F src/sqliteLimit.h 504a3161886d2938cbd163054ad620b8356df758
 F src/status.c 237b193efae0cf6ac3f0817a208de6c6c6ef6d76
 F src/table.c cc86ad3d6ad54df7c63a3e807b5783c90411a08d
@@ -201,7 +201,7 @@ F src/test_tclvar.c 9e42fa59d3d2f064b7ab8628e7ab2dc8a9fe93d4
 F src/test_thread.c b8a1ab7ca1a632f18e8a361880d5d65eeea08eac
 F src/test_wsd.c 3ae5101de6cbfda2720152ab659ea84079719241
 F src/tokenize.c af8a56e6a50c5042fc305bfa796275e9bf26ff2b
-F src/trigger.c d2f31617a1852f7365aca54c5c85743b9114d462
+F src/trigger.c 643e27f94a0112071a993f457d6c4aae24782944
 F src/update.c a7a5f60bf65a88557b434ac40f2ae6d2f7ad2d2d
 F src/utf.c 99cf927eabb104621ba889ac0dd075fc1657ad30
 F src/util.c 59d4e9456bf1fe581f415a783fa0cee6115c8f35
@@ -330,8 +330,8 @@ F test/expr.test 9f521ae22f00e074959f72ce2e55d46b9ed23f68
 F test/filectrl.test 8923a6dc7630f31c8a9dd3d3d740aa0922df7bf8
 F test/filefmt.test 84e3d0fe9f12d0d2ac852465c6f8450aea0d6f43
 F test/fkey1.test 01c7de578e11747e720c2d9aeef27f239853c4da
-F test/fkey2.test b879ba958126da0bfdfcf5d4532840c0f5956c72
-F test/fkey3.test 2183cac9075f3aae4875106eb9255bb73618444e
+F test/fkey2.test d26f490838bb067d654f4daae3aa90a8a8c8b562
+F test/fkey3.test 4d8d87a72e0dee5b5411cf10dc05ad9edebbeac8
 F test/fkey_malloc.test da912d000bb6ceb1cd11b655de1989762fa71ceb
 F test/format4.test 1f0cac8ff3895e9359ed87e41aaabee982a812eb
 F test/fts1a.test 46090311f85da51bb33bd5ce84f7948359c6d8d7
@@ -755,7 +755,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P b4a10c39e726dc190e9597e382baddc034294114
-R 8c38d646c8a9549ba486066fb27ea41b
+P 9e503e2d0428c9e8df878c7c6594790232cca4e0
+R a460411e3ababe633f79d4b6b7ec5ee3
 U dan
-Z 7018674b123841c492121f6d9b33b5de
+Z e4a35317c102426902fe4c436cf5658b

manifest.uuid

@@ -1 +1 @@
-9e503e2d0428c9e8df878c7c6594790232cca4e0
+8353808c9e70412fdee31bfda7810e948f1c7485

src/build.c

@@ -2061,6 +2061,7 @@ void sqlite3DropTable(Parse *pParse, SrcList *pName, int isView, int noErr){
       sqlite3VdbeAddOp0(v, OP_VBegin);
     }
 #endif
+    sqlite3FkDropTable(pParse, pName, pTab);
 
     /* Drop all triggers associated with the table being dropped. Code
     ** is generated to remove entries from sqlite_master and/or

src/fkey.c

@@ -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 

src/sqliteInt.h

@@ -2122,6 +2122,7 @@ struct Parse {
   u32 oldmask;         /* Mask of old.* columns referenced */
   u8 eTriggerOp;       /* TK_UPDATE, TK_INSERT or TK_DELETE */
   u8 eOrconf;          /* Default ON CONFLICT policy for trigger steps */
+  u8 disableTriggers;  /* True to disable triggers */
 
   /* Above is constant between recursions.  Below is reset before and after
   ** each recursion */
@@ -2949,15 +2950,17 @@ VTable *sqlite3GetVTable(sqlite3*, Table*);
 */
 #if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
   void sqlite3FkCheck(Parse*, Table*, ExprList*, int, int);
+  void sqlite3FkDropTable(Parse*, SrcList *, Table*);
   void sqlite3FkActions(Parse*, Table*, ExprList*, int);
   int sqlite3FkRequired(Parse*, Table*, ExprList*);
   u32 sqlite3FkOldmask(Parse*, Table*, ExprList*);
   FKey *sqlite3FkReferences(Table *);
 #else
-  #define sqlite3FkCheck(a,b,c,d,e)
   #define sqlite3FkActions(a,b,c,d)
-  #define sqlite3FkRequired(a,b,c) 0
+  #define sqlite3FkCheck(a,b,c,d,e)
+  #define sqlite3FkDropTable(a,b,c)
   #define sqlite3FkOldmask(a,b,c)  0
+  #define sqlite3FkRequired(a,b,c) 0
 #endif
 #ifndef SQLITE_OMIT_FOREIGN_KEY
   void sqlite3FkDelete(Table*);

src/trigger.c

@@ -50,6 +50,10 @@ 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;
     for(p=sqliteHashFirst(&pTmpSchema->trigHash); p; p=sqliteHashNext(p)){

test/fkey2.test

@@ -75,12 +75,14 @@ ifcapable {!foreignkey||!trigger} {
 
 proc drop_all_tables {{db db}} {
   set tbls [execsql {SELECT name FROM sqlite_master WHERE type = 'table'}]
+  execsql { PRAGMA foreign_keys = OFF }
   foreach t [execsql {
     SELECT name FROM sqlite_master 
     WHERE type = 'table' AND name NOT like 'sqlite_%'
   }] {
     execsql "DROP TABLE $t"
   }
+  execsql { PRAGMA foreign_keys = ON }
 }
 
 execsql { PRAGMA foreign_keys = on }

test/fkey3.test

@@ -48,5 +48,33 @@ do_test fkey3-1.3 {
     DROP TABLE t1;
   }
 } {1 {foreign key constraint failed}}
- 
+
+do_test fkey3-1.4 {
+  execsql {
+    DROP TABLE t2;
+  }
+} {}
+
+do_test fkey3-1.5 {
+  execsql {
+    DROP TABLE t1;
+  }
+} {}
+
+do_test fkey3-2.1 {
+  execsql {
+    PRAGMA foreign_keys=ON;
+    CREATE TABLE t1(x INTEGER PRIMARY KEY);
+    INSERT INTO t1 VALUES(100);
+    INSERT INTO t1 VALUES(101);
+    CREATE TABLE t2(y INTEGER PRIMARY KEY REFERENCES t1 (x) ON UPDATE SET NULL);
+  }
+  execsql {
+    INSERT INTO t2 VALUES(100);
+    INSERT INTO t2 VALUES(101);
+    SELECT 1, x FROM t1;
+    SELECT 2, y FROM t2;
+  }
+} {1 100 1 101 2 100 2 101}
+
 finish_test