core-admin/qvm-tools/qvm-sync-clock

#!/usr/bin/python3
# -*- encoding: utf8 -*-
#
# The Qubes OS Project, http://www.qubes-os.org
#
# Copyright (C) 2010  Marek Marczykowski <marmarek@invisiblethingslab.com>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, see <https://www.gnu.org/licenses/>.
#
#
import sys
import os
import re
import subprocess
from qubesadmin import Qubes

def main():
    if os.geteuid() != 0:
        sys.stderr.write('This program must be run as root to set the date, aborting!\n')
        sys.exit(1)
    app = Qubes()
    clockvm = app.clockvm

    p = clockvm.run_service('qubes.GetDate')
    untrusted_date_out = p.stdout.read(25).decode('ascii', errors='strict')
    untrusted_date_out = untrusted_date_out.strip()

    if not re.match(r'^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\+00:?00$', untrusted_date_out):
        sys.stderr.write('Invalid date received, aborting!\n')
        sys.exit(1)
    date_out = untrusted_date_out
    subprocess.check_call(['date', '-u', '-Iseconds', '-s', date_out],
        stdout=subprocess.DEVNULL)
    subprocess.check_call(['hwclock', '--systohc'],
        stdout=subprocess.DEVNULL)

if __name__ == '__main__':
    main()