def _GetLink(self):
    if self._link is None:
      cpio_archive_file_entry = self.GetCPIOArchiveFileEntry()
      if not self._is_virtual and cpio_archive_file_entry is None:
        raise errors.BackEndError(
            u'Missing CPIO archive file entry in non-virtual file entry.')

      self._link = u''
      if stat.S_ISLNK(cpio_archive_file_entry.mode):
        cpio_archive_file = self._file_system.GetCPIOArchiveFile()
        link_data = cpio_archive_file.ReadDataAtOffset(
            cpio_archive_file_entry.data_offset,
            cpio_archive_file_entry.data_size)

        # TODO: should this be ASCII?
        self._link = link_data.decode(u'ascii')

    return self._link
Return user unique id provided by service. For google user email
dataset/ETHPy150Open log2timeline/dfvfs/dfvfs/vfs/cpio_file_entry.py/CPIOFileEntry._GetLink--crossover with--dataset/ETHPy150Open omab/python-social-auth/social/backends/google.py/GoogleOpenId.get_user_id