Index: src/test_demovfs.c
==================================================================
--- src/test_demovfs.c
+++ src/test_demovfs.c
@@ -238,10 +238,13 @@
   nRead = read(p->fd, zBuf, iAmt);
 
   if( nRead==iAmt ){
     return SQLITE_OK;
   }else if( nRead>=0 ){
+    if( nRead<iAmt ){
+      memset(&((char*)zBuf)[nRead], 0, iAmt-nRead);
+    }
     return SQLITE_IOERR_SHORT_READ;
   }
 
   return SQLITE_IOERR_READ;
 }
@@ -367,11 +370,11 @@
 
 /*
 ** No xFileControl() verbs are implemented by this VFS.
 */
 static int demoFileControl(sqlite3_file *pFile, int op, void *pArg){
-  return SQLITE_OK;
+  return SQLITE_NOTFOUND;
 }
 
 /*
 ** The xSectorSize() and xDeviceCharacteristics() methods. These two
 ** may return special values allowing SQLite to optimize file-system