#!/usr/bin/env python3
#
# resets the clock on a resumed internet connected openbsd guest running on vmware
#
# restart ntpd (ntpd_flags="-s") when guest resumes
# - make sure current user can "doas rcctl ntpd restart"
#
# (c) 2020 torh-scrape@bogus.net
#
# this won't work on openbsd-current (6.6>), as "-s" has been removed
# from ntpd; see https://marc.info/?l=openbsd-misc&m=158158413909971&w=2
#
from pygtail import Pygtail
import re
import tempfile
from subprocess import DEVNULL, STDOUT, check_call
import time
import os
import signal

def sigTerm(signum,fr):
	os.close(fd)
	os.remove(tf)
	exit()

if __name__ == '__main__':
	tailfile="/var/log/messages"

	m = re.compile(".* /bsd: VMware guest resuming from suspended state.*")

	fd, tf = tempfile.mkstemp(dir="/tmp")

	signal.signal(signal.SIGTERM, sigTerm)
	signal.signal(signal.SIGINT, sigTerm)

	for line in Pygtail(tailfile, read_from_end=True, offset_file=tf):
		pass

	while True:
		for line in Pygtail(tailfile, read_from_end=True, offset_file=tf):
			if m.match(line):
				with open(os.devnull, 'wb') as devnull:
					try:
						check_call(['/usr/bin/doas', '/usr/sbin/rcctl', 'restart', 'ntpd'], stdout=DEVNULL)
					except Exception as e:
						print(e)					
		time.sleep(1)