1 files changed, 63 insertions, 1 deletions
diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index 447ba57a1..a45f7a289 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -75,6 +75,7 @@ const char *sqlite3_sql(sqlite3_stmt *pStmt){
 void sqlite3VdbeSwap(Vdbe *pA, Vdbe *pB){
   Vdbe tmp, *pTmp;
   char *zTmp;
+  assert( pA->db==pB->db );
   tmp = *pA;
   *pA = *pB;
   *pB = tmp;
@@ -2884,6 +2885,7 @@ UnpackedRecord *sqlite3VdbeRecordUnpack(
     pMem->db = pKeyInfo->db;
     /* pMem->flags = 0; // sqlite3VdbeSerialGet() will set this for us */
     pMem->zMalloc = 0;
+    pMem->z = 0;
     d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
     pMem++;
     u++;
@@ -2909,7 +2911,7 @@ void sqlite3VdbeDeleteUnpackedRecord(UnpackedRecord *p){
     ** strings and blobs static.  And none of the elements are
     ** ever transformed, so there is never anything to delete.
     */
-    if( NEVER(pMem->zMalloc) ) sqlite3VdbeMemRelease(pMem);
+    if( pMem->zMalloc ) sqlite3VdbeMemRelease(pMem);
   }
 #endif
   if( p->flags & UNPACKED_NEED_FREE ){
@@ -3242,3 +3244,63 @@ void sqlite3VdbeSetVarmask(Vdbe *v, int iVar){
     v->expmask |= ((u32)1 << (iVar-1));
   }
 }
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+/*
+** Invoke the pre-update hook. If this is an UPDATE or DELETE pre-update call,
+** then cursor passed as the second argument should point to the row about
+** to be update or deleted. If the application calls sqlite3_preupdate_old(),
+** the required value will be read from the row the cursor points to.
+*/
+void sqlite3VdbePreUpdateHook(
+  Vdbe *v,                        /* Vdbe pre-update hook is invoked by */
+  VdbeCursor *pCsr,               /* Cursor to grab old.* values from */
+  int op,                         /* SQLITE_INSERT, UPDATE or DELETE */
+  const char *zDb,                /* Database name */
+  Table *pTab,                    /* Modified table */
+  i64 iKey1,                      /* Initial key value */
+  int iReg                        /* Register for new.* record */
+){
+  sqlite3 *db = v->db;
+  i64 iKey2;
+  PreUpdate preupdate;
+  const char *zTbl = pTab->zName;
+
+  assert( db->pPreUpdate==0 );
+  memset(&preupdate, 0, sizeof(PreUpdate));
+  if( op==SQLITE_UPDATE ){
+    iKey2 = v->aMem[iReg].u.i;
+  }else{
+    iKey2 = iKey1;
+  }
+
+  preupdate.v = v;
+  preupdate.pCsr = pCsr;
+  preupdate.op = op;
+  preupdate.iNewReg = iReg;
+  preupdate.keyinfo.db = db;
+  preupdate.keyinfo.enc = ENC(db);
+  preupdate.keyinfo.nField = pCsr->nField;
+  preupdate.iKey1 = iKey1;
+  preupdate.iKey2 = iKey2;
+  preupdate.iPKey = pTab->iPKey;
+
+  db->pPreUpdate = &preupdate;
+  db->xPreUpdateCallback(db->pPreUpdateArg, db, op, zDb, zTbl, iKey1, iKey2);
+  db->pPreUpdate = 0;
+  sqlite3DbFree(db, preupdate.aRecord);
+  if( preupdate.pUnpacked ){
+    sqlite3VdbeDeleteUnpackedRecord(preupdate.pUnpacked);
+  }
+  if( preupdate.pNewUnpacked ){
+    sqlite3VdbeDeleteUnpackedRecord(preupdate.pNewUnpacked);
+  }
+  if( preupdate.aNew ){
+    int i;
+    for(i=0; i<pCsr->nField; i++){
+      sqlite3VdbeMemRelease(&preupdate.aNew[i]);
+    }
+    sqlite3DbFree(db, preupdate.aNew);
+  }
+}
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */