don't show other users file if the filesystem is not index already

lib/filecache/cached.php

@@ -55,6 +55,9 @@ class OC_FileCache_Cached{
 			$root=OC_Filesystem::getRoot();
 		}
 		$parent=OC_FileCache::getId($path,$root);
+		if($parent==-1){
+			return array();
+		}
 		$query=OC_DB::prepare('SELECT path,name,ctime,mtime,mimetype,size,encrypted,versioned,writable FROM *PREFIX*fscache WHERE parent=? AND (mimetype LIKE ? OR mimetype = ?)');
 		$result=$query->execute(array($parent, $mimetype_filter.'%', 'httpd/unix-directory'))->fetchAll();
 		if(is_array($result)){