Index: ext/fts3/fts3.c
==================================================================
--- ext/fts3/fts3.c
+++ ext/fts3/fts3.c
@@ -908,15 +908,20 @@
 ** the output value undefined. Otherwise SQLITE_OK is returned.
 **
 ** This function is used when parsing the "prefix=" FTS4 parameter.
 */
 static int fts3GobbleInt(const char **pp, int *pnOut){
+  const MAX_NPREFIX = 10000000;
   const char *p;                  /* Iterator pointer */
   int nInt = 0;                   /* Output value */
 
   for(p=*pp; p[0]>='0' && p[0]<='9'; p++){
     nInt = nInt * 10 + (p[0] - '0');
+    if( nInt>MAX_NPREFIX ){
+      nInt = 0;
+      break;
+    }
   }
   if( p==*pp ) return SQLITE_ERROR;
   *pnOut = nInt;
   *pp = p;
   return SQLITE_OK;
@@ -964,13 +969,14 @@
   memset(aIndex, 0, sizeof(struct Fts3Index) * nIndex);
   if( zParam ){
     const char *p = zParam;
     int i;
     for(i=1; i<nIndex; i++){
-      int nPrefix;
+      int nPrefix = 0;
       if( fts3GobbleInt(&p, &nPrefix) ) return SQLITE_ERROR;
-      if( nPrefix<=0 ){
+      assert( nPrefix>=0 );
+      if( nPrefix==0 ){
         nIndex--;
         i--;
       }else{
         aIndex[i].nPrefix = nPrefix;
       }

Index: src/vdbe.c
==================================================================
--- src/vdbe.c
+++ src/vdbe.c
@@ -6035,19 +6035,24 @@
 ** P2 is a register that holds the name of a virtual table in database 
 ** P1. Call the xCreate method for that table.
 */
 case OP_VCreate: {
   Mem sMem;          /* For storing the record being decoded */
+  const char *zTab;  /* Name of the virtual table */
+
   memset(&sMem, 0, sizeof(sMem));
   sMem.db = db;
+  /* Because P2 is always a static string, it is impossible for the
+  ** sqlite3VdbeMemCopy() to fail */
+  assert( (aMem[pOp->p2].flags & MEM_Str)!=0 );
+  assert( (aMem[pOp->p2].flags & MEM_Static)!=0 );
   rc = sqlite3VdbeMemCopy(&sMem, &aMem[pOp->p2]);
-  if( rc==SQLITE_OK ){
-    const char *zTab = (const char*)sqlite3_value_text(&sMem);
-    assert( zTab || db->mallocFailed );
-    if( zTab ){
-      rc = sqlite3VtabCallCreate(db, pOp->p1, zTab, &p->zErrMsg);
-    }
+  assert( rc==SQLITE_OK );
+  zTab = (const char*)sqlite3_value_text(&sMem);
+  assert( zTab || db->mallocFailed );
+  if( zTab ){
+    rc = sqlite3VtabCallCreate(db, pOp->p1, zTab, &p->zErrMsg);
   }
   sqlite3VdbeMemRelease(&sMem);
   break;
 }
 #endif /* SQLITE_OMIT_VIRTUALTABLE */

Index: test/shell4.test
==================================================================
--- test/shell4.test
+++ test/shell4.test
@@ -120,15 +120,17 @@
   catchcmd ":memory:" "CREATE TABLE t1(x);\n.trace off\n.trace off\n"
 } {0 {}}
 do_test shell4-2.3 {
   catchcmd ":memory:" ".trace stdout\n.trace\n.trace off\n.dump\n"
 } {/^1 {PRAGMA.*Usage:.*}$/}
+ifcapable trace {
 do_test shell4-2.4 {
   catchcmd ":memory:" ".trace stdout\nCREATE TABLE t1(x);SELECT * FROM t1;"
 } {0 {CREATE TABLE t1(x);
 SELECT * FROM t1;}}
 do_test shell4-2.5 {
   catchcmd ":memory:" "CREATE TABLE t1(x);\n.trace stdout\nSELECT * FROM t1;"
 } {0 {SELECT * FROM t1;}}
+}
 
 
 finish_test

Index: test/vtab2.test
==================================================================
--- test/vtab2.test
+++ test/vtab2.test
@@ -133,22 +133,24 @@
   execsql { SELECT * FROM fkey }
 } {t1 a}
 
 #-------------------------------------------------------------------------
 #
-reset_db
-do_execsql_test 5.1 {
-  PRAGMA encoding='UTF16';
-}
-
-do_test 5.2 {
-  sqlite3_exec_hex db { CREATE VIRTUAL TABLE %C8 USING fts3 }
-} {0 {}}
-
-do_test 5.3 {
-  sqlite3_exec_hex db { CREATE VIRTUAL TABLE %C9 USING s }
-} {/1 {malformed database schema.* already exists}/}
+ifcapable fts3 {
+  reset_db
+  do_execsql_test 5.1 {
+    PRAGMA encoding='UTF16';
+  }
+
+  do_test 5.2 {
+    sqlite3_exec_hex db { CREATE VIRTUAL TABLE %C8 USING fts3 }
+  } {0 {}}
+
+  do_test 5.3 {
+    sqlite3_exec_hex db { CREATE VIRTUAL TABLE %C9 USING s }
+  } {/1 {malformed database schema.* already exists}/}
+}
 
 
 
 finish_test