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 _storage(self):
        """
        Return the configured django storage backend.
        """
        config = settings.VERIFY_STUDENT["SOFTWARE_SECURE"]

        # Default to the S3 backend for backward compatibility
        storage_class = config.get("STORAGE_CLASS", "storages.backends.s3boto.S3BotoStorage")
        storage_kwargs = config.get("STORAGE_KWARGS", {})

        # Map old settings to the parameters expected by the storage backend
        if "AWS_ACCESS_KEY" in config:
            storage_kwargs["access_key"] = config["AWS_ACCESS_KEY"]
        if "AWS_SECRET_KEY" in config:
            storage_kwargs["secret_key"] = config["AWS_SECRET_KEY"]
        if "S3_BUCKET" in config:
            storage_kwargs["bucket"] = config["S3_BUCKET"]
            storage_kwargs["querystring_expire"] = self.IMAGE_LINK_DURATION

        return get_storage(storage_class, **storage_kwargs)