def METHOD_NAME():
    """
    If sanlock daemon is running, return the supplementary groups.
    """
    try:
        with open(PID_FILE) as f:
            sanlock_pid = f.readline().strip()
    except FileNotFoundError:
        return None
    proc_status = os.path.join('/proc', sanlock_pid, 'status')
    try:
        with open(proc_status) as f:
            status = f.read()
    except FileNotFoundError:
        return None
    match = re.search(r"^Groups:\t?(.*)$", status, re.MULTILINE)
    if not match:
        raise RuntimeError(
            "Cannot get sanlock daemon groups: {!r}".format(status))
    return {grp.getgrgid(int(s)).gr_name
            for s in match.group(1).split()}