#!/usr/bin/python -O
#
# Copyright 2005 Sven Wegener <swegener@gentoo.org>
# Distributed under the terms of the GNU General Public License v2
#
# $Id: ssh-master 283 2005-09-06 13:56:20Z sven $
#

from string import strip
from os import getenv, wait, fork, spawnlp, P_NOWAIT
from os import open, close, dup2, O_RDWR
from sys import exit
from time import time, sleep
from signal import alarm, signal, SIGALRM
from copy import copy

if fork():
	exit(0)

# re-open stdin, stdout and stderr to /dev/null
devnull = open('/dev/null', O_RDWR)
dup2(devnull, 0)
dup2(devnull, 1)
dup2(devnull, 2)
close(devnull)

hostdict = {}
waithostdict = {}

hosts = file(getenv('HOME') + '/.ssh/master_hosts').readlines()
hosts = map(strip, hosts)
hosts = filter(lambda (line): line and not line.startswith('#'), hosts)

def spawnmaster(host):
	pid = spawnlp(P_NOWAIT, 'ssh', 'ssh', '-nNM', host)
	hostdict[pid] = host

for host in hosts:
	spawnmaster(host)

def signal_alarm(sig, stack):
	myhostdict = copy(waithostdict)
	for x, y in myhostdict.iteritems():
		if y < time():
			spawnmaster(x)
			del waithostdict[x]
	alarm(10)

signal(SIGALRM, signal_alarm)
alarm(30)

while True:
	try:
		pid, status = wait()
	except OSError, e:
		sleep(5)
		continue
	except:
		raise

	host = hostdict[pid]
	del hostdict[pid]

	waithostdict[host] = time() + 15