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 program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
#
import sys
import re
import subprocess
from qubesadmin import Qubes

def main():

    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!')
        sys.exit(1)
    subprocess.check_call(['date', '-u', '-Iseconds', '-s', untrusted_date_out],
        stdout=subprocess.DEVNULL)
    subprocess.check_call(['hwclock', '--systohc'],
        stdout=subprocess.DEVNULL)

if __name__ == '__main__':
    main()