def get_sha512_manifest(zfile):
    """
    Get MANIFEST.MF from a bar file.

    :param zfile: Open (!!!) ZipFile instance.
    :type zfile: zipfile.ZipFile
    """
    names = zfile.namelist()
    manifest = None
    for name in names:
        if name.endswith("MANIFEST.MF"):
            manifest = name
            break
    if manifest is None:
        raise SystemExit
    return manifest