1 files changed, 84 insertions, 0 deletions
diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index eaf5780ab..9e702edcd 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -880,6 +880,90 @@ static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs){
   assert( p->bIsReader!=0 || DbMaskAllZero(p->btreeMask) );
 }
 
+#ifdef SQLITE_DEBUG
+/*
+** Check to see if a subroutine contains a jump to a location outside of
+** the subroutine.  If a jump outside the subroutine is detected, add code
+** that will cause the program to halt with an error message.
+**
+** The subroutine consists of opcodes between iFirst and iLast.  Jumps to
+** locations within the subroutine are acceptable.  iRetReg is a register
+** that contains the return address.  Jumps to outside the range of iFirst
+** through iLast are also acceptable as long as the jump destination is
+** an OP_Return to iReturnAddr.
+**
+** A jump to an unresolved label means that the jump destination will be
+** beyond the current address.  That is normally a jump to an early
+** termination and is consider acceptable.
+**
+** This routine only runs during debug builds.  The purpose is (of course)
+** to detect invalid escapes out of a subroutine.  The OP_Halt opcode
+** is generated rather than an assert() or other error, so that ".eqp full"
+** will still work to show the original bytecode, to aid in debugging.
+*/
+void sqlite3VdbeNoJumpsOutsideSubrtn(
+  Vdbe *v,          /* The byte-code program under construction */
+  int iFirst,       /* First opcode of the subroutine */
+  int iLast,        /* Last opcode of the subroutine */
+  int iRetReg       /* Subroutine return address register */
+){
+  VdbeOp *pOp;
+  Parse *pParse;
+  int i;
+  sqlite3_str *pErr = 0;
+  assert( v!=0 );
+  pParse = v->pParse;
+  assert( pParse!=0 );
+  if( pParse->nErr ) return;
+  assert( iLast>=iFirst );
+  assert( iLast<v->nOp );
+  pOp = &v->aOp[iFirst];
+  for(i=iFirst; i<=iLast; i++, pOp++){
+    if( (sqlite3OpcodeProperty[pOp->opcode] & OPFLG_JUMP)!=0 ){
+      int iDest = pOp->p2;   /* Jump destination */
+      if( iDest==0 ) continue;
+      if( pOp->opcode==OP_Gosub ) continue;
+      if( iDest<0 ){
+        int j = ADDR(iDest);
+        assert( j>=0 );
+        if( j>=-pParse->nLabel || pParse->aLabel[j]<0 ){
+          continue;
+        }
+        iDest = pParse->aLabel[j];
+      }
+      if( iDest<iFirst || iDest>iLast ){
+        int j = iDest;
+        for(; j<v->nOp; j++){
+          VdbeOp *pX = &v->aOp[j];
+          if( pX->opcode==OP_Return ){
+            if( pX->p1==iRetReg ) break;
+            continue;
+          }
+          if( pX->opcode==OP_Noop ) continue;
+          if( pX->opcode==OP_Explain ) continue;
+          if( pErr==0 ){
+            pErr = sqlite3_str_new(0);
+          }else{
+            sqlite3_str_appendchar(pErr, 1, '\n');
+          }
+          sqlite3_str_appendf(pErr,
+              "Opcode at %d jumps to %d which is outside the "
+              "subroutine at %d..%d",
+              i, iDest, iFirst, iLast);
+          break;
+        }
+      }
+    }
+  }
+  if( pErr ){
+    char *zErr = sqlite3_str_finish(pErr);
+    sqlite3VdbeAddOp4(v, OP_Halt, SQLITE_INTERNAL, OE_Abort, 0, zErr, 0);
+    sqlite3_free(zErr);
+    sqlite3MayAbort(pParse);
+  }
+}
+#endif /* SQLITE_DEBUG */
+
 /*
 ** Return the address of the next instruction to be inserted.
 */