Ticket #18855: get_attached_file-returns-false.diff

post.php

@@ -168 +168 @@
  *
  * @param int $attachment_id Attachment ID.
  * @param bool $unfiltered Whether to apply filters.
- * @return string The file path to the attached file.
+ * @return string|bool The file path to the attached file, or false if the attachment does not exist.
  */
 function get_attached_file( $attachment_id, $unfiltered = false ) {
         $file = get_post_meta( $attachment_id, '_wp_attached_file', true );
-        // If the file is relative, prepend upload dir
-        if ( 0 !== strpos($file, '/') && !preg_match('|^.:\\\|', $file) && ( ($uploads = wp_upload_dir()) && false === $uploads['error'] ) )
-                $file = $uploads['basedir'] . "/$file";
+        if ( ! empty ( $file ) ) {
+                // If the file is relative, prepend upload dir
+                if ( 0 !== strpos($file, '/') && !preg_match('|^.:\\\|', $file) && ( ($uploads = wp_upload_dir()) && false === $uploads['error'] ) )
+                        $file = $uploads['basedir'] . "/$file";
+        }
         if ( $unfiltered )
                 return $file;
         return apply_filters( 'get_attached_file', $file, $attachment_id );