gistfile1.php

<?php
// Create the return filepath. We add the bucket file path if
  // the a custom domain is not being used
  preg_match('@^(?:https?://)?([^/]+)@i', $settings['mm_s3_server_url'], $domain);

  if ( $domain[1] == 's3.amazonaws.com') {
    $s3_filename = $bucket . '/' . $s3_filename;
  }
  return $settings['mm_s3_server_url'] . $s3_filename;
?>