Add a new OP_StackDepth opcode to help detect VDBE stack leaks early,

before they cause damage.  For diagnostics in ticket #2832. (CVS 4612)

FossilOrigin-Name: 3fd6a267533cedcca9b8ba3533c107d7341a06c6

manifest

@@ -1,5 +1,5 @@
-C Fix\stest\snumbering\sin\stkt2822.test.\sTicket\s#2830.\s(CVS\s4611)
+C Add\sa\snew\sOP_StackDepth\sopcode\sto\shelp\sdetect\sVDBE\sstack\sleaks\searly,\r\nbefore\sthey\scause\sdamage.\s\sFor\sdiagnostics\sin\sticket\s#2832.\s(CVS\s4612)
-D 2007-12-12T04:38:27
+D 2007-12-12T12:00:46
 F Makefile.arm-wince-mingw32ce-gcc ac5f7b2cef0cd850d6f755ba6ee4ab961b1fadf7
 F Makefile.in 0590398f62fc2c456ff4c45e9741f5a718b7e2ac
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -164,11 +164,11 @@ F src/test_tclvar.c b2d1115e4d489179d3f029e765211b2ad527ba59
 F src/test_thread.c a98d69cae883e53d3686fc25889a5fa5f51439f8
 F src/tokenize.c 67e42600ab34f976f2b1288c499ad6c98d652f0e
 F src/trigger.c 66695e1375b969ea41a38dec9f40ea28bb0ac767
-F src/update.c 2add92a6159fa73128653706574afbcd8fd1dd80
+F src/update.c 3725377d6226f6a1f15885e112435df3a5e4770d
 F src/utf.c ef4b7d83bae533b76c3e1bf635b113fdad86a736
 F src/util.c 05f31144bbd3f1a24f4139ae029c42545cb72624
 F src/vacuum.c 25ffbd766f25bca099ead1c1e11f5528c86102b8
-F src/vdbe.c a99beac1162fa490c4b75ac36ed97146ab181837
+F src/vdbe.c 24376fd0c28a52ebb410292a2261e5174d862cc0
 F src/vdbe.h 79e09ff13b85457abe437d9814454534ebbc1fe3
 F src/vdbeInt.h 630145b9bfaa19190ab491f52658a7db550f2247
 F src/vdbeapi.c dd2c43317294e0a013e9f634ee4209a3ea459b43
@@ -598,7 +598,7 @@ F www/tclsqlite.tcl 8be95ee6dba05eabcd27a9d91331c803f2ce2130
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl fc46eae081251c3c181bd79c5faef8195d7991a5
-P 9335c940504f5979066b70ec445b57acfb251713
+P 8fe8e9c460e0f8ebc4267de96b0c971cb6370861
-R d03a5445f8be128fa7f48f15551925f2
+R 6bd8f89e70a38f2a5c36552ce2b40f8f
-U danielk1977
+U drh
-Z bf201abd015205614969c923308ec87e
+Z 14e8caa139e0c85a2dd57b679935e880

manifest.uuid

@@ -1 +1 @@
-8fe8e9c460e0f8ebc4267de96b0c971cb6370861
+3fd6a267533cedcca9b8ba3533c107d7341a06c6

src/update.c

@@ -12,7 +12,7 @@
 ** This file contains C code routines that are called by the parser
 ** to handle UPDATE statements.
 **
-** $Id: update.c,v 1.141 2007/11/11 18:36:34 drh Exp $
+** $Id: update.c,v 1.142 2007/12/12 12:00:46 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -330,6 +330,7 @@ void sqlite3Update(
     /* The top of the update loop for when there are triggers.
     */
     addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);
+    sqlite3VdbeAddOp(v, OP_StackDepth, -1, 0);
     mem1 = pParse->nMem++;
     sqlite3VdbeAddOp(v, OP_MemStore, mem1, 0);
     
@@ -427,6 +428,7 @@ void sqlite3Update(
     */
     if( !triggers_exist ){
       addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);
+      sqlite3VdbeAddOp(v, OP_StackDepth, -1, 0);
       sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
     }
     sqlite3VdbeAddOp(v, OP_NotExists, iCur, addr);

src/vdbe.c

@@ -43,7 +43,7 @@
 ** in this file for details.  If in doubt, do not deviate from existing
 ** commenting and indentation practices when changing or adding code.
 **
-** $Id: vdbe.c,v 1.656 2007/12/04 16:54:53 drh Exp $
+** $Id: vdbe.c,v 1.657 2007/12/12 12:00:46 drh Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -692,6 +692,28 @@ case OP_Halt: {            /* no-push */
   goto vdbe_return;
 }
 
+/* Opcode:  StackDepth P1 * *
+**
+** If P1 is less than zero, then store the current stack depth
+** in P1.  If P1 is zero or greater, verify that the current stack
+** depth is equal to P1 and throw an exception if it is not.
+**
+** This opcode is used for internal consistency checking.
+*/
+case OP_StackDepth: {       /* no-push */
+  if( pOp->p1<0 ){
+    pOp->p1 = pTos - p->aStack + 1;
+  }else if( pOp->p1!=pTos - p->aStack + 1 ){
+    p->pTos = pTos;
+    p->rc = SQLITE_ERROR;
+    p->pc = pc;
+    p->errorAction = OE_Rollback;
+    sqlite3SetString(&p->zErrMsg, "internal VDBE stack overflow", (char*)0);
+    goto vdbe_return;
+  }
+  break;
+}
+
 /* Opcode: Integer P1 * *
 **
 ** The 32-bit integer value P1 is pushed onto the stack.