Prevent renaming ML object into existing file.

When renaming objects in the Media Library,
s9y didn't check if a file with the same
name already exists, resulting in a file
name collision deleting both files from
the database _and_ from disk.

Add a check to avoid that.

An error message would be nice, too, but
that may be added later on.

Tested on s9y-stable test instance.

Cherry-picked from master branch.

Signed-off-by: Thomas Hochstein <thh@inter.net>

docs/NEWS

@@ -20,6 +20,11 @@ Version 2.3.3-beta1 ()
      Also fixes missing "keep strip tags" configuration option
 
    * Fix: Add valid HTTP referrer when trying to delete a
+
+   * Fix: Prevent renaming a ML object into an existing file,
+          resulting in deletion of both from disk and database.
+
+   * Fix invalid HTTP referrer error when trying to delete a
      trackback from the frontend
 
    * Use the video tag for videos in the Medialibrary, also when

include/functions_images.inc.php

@@ -2261,6 +2261,10 @@ function serendipity_renameFile($id, $newName, $path = null) {
     
     $newPath = "{$imgBase}{$path}{$newName}.{$file['extension']}";
 
+    if (file_exists($newPath)) {
+        return false;
+    }
+    
     rename("{$imgBase}{$file['path']}{$file['realname']}", $newPath);
     
     serendipity_renameThumbnails($id, "{$path}$newName");