public static function getFilename($bucket, $object) {
    if (self::validateBucketName($bucket) === false) {
      throw new \InvalidArgumentException(
          sprintf('Invalid cloud storage bucket name \'%s\'',
                  htmlspecialchars($bucket)));
    }

    if (self::validateObjectName($object) === false) {
      throw new \InvalidArgumentException(
          sprintf('Invalid cloud storage object name \'%s\'',
                  htmlspecialchars($object)));
    }

    return sprintf(self::GS_FILENAME_FORMAT, $bucket, $object);
  }