def get_dir_from_zipfile(zip_file, fallback=None):
    """Return the name of the root folder in a zip file.

    :param zip_file: a :class:`zipfile.ZipFile` instance.
    :param fallback: if `None`, the name of the zip file is used. This is
        returned if the zip file contains more than one top-level directory,
        or none at all.
    """
    fallback = fallback or zip_file.filename
    directories = [name for name in zip_file.namelist() if name.endswith("/")
                   and len(PurePath(name).parts) == 1]
    return fallback if len(directories) > 1 else directories[0]
def _get_snapshot_status(self, snapshot_id):
        resp, body = self.get_snapshot(snapshot_id)
        status = body['status']
        # NOTE(afazekas): snapshot can reach an "error"
        # state in a "normal" lifecycle
        if (status == 'error'):
            raise exceptions.SnapshotBuildErrorException(
                snapshot_id=snapshot_id)

        return status