PlexConnect_daemon.py

#!/usr/bin/python

"""
PlexConnectDaemon

Creates a proper daemon on mac/linux
"""

import os
import sys
import signal
import argparse
import atexit
from PlexConnect import startup, shutdown, run, cmdShutdown


def daemonize(args):
    """
    do the UNIX double-fork magic, see Stevens' "Advanced
    Programming in the UNIX Environment" for details (ISBN 0201563177)
    """

    # Make a non-session-leader child process
    try:
        pid = os.fork()
        if pid != 0:
            sys.exit(0)
    except OSError, e:
        raise RuntimeError("1st fork failed: %s [%d]" % (e.strerror, e.errno))

    # decouple from parent environment
    os.setsid()

    # Make sure I can read my own files and shut out others
    prev = os.umask(0)
    os.umask(prev and int('077', 8))

    # Make the child a session-leader by detaching from the terminal
    try:
        pid = os.fork()
        if pid != 0:
            sys.exit(0)
    except OSError, e:
        raise RuntimeError("2nd fork failed: %s [%d]" % (e.strerror, e.errno))

    # redirect standard file descriptors
    sys.stdout.flush()
    sys.stderr.flush()
    si = file('/dev/null', 'r')
    so = file('/dev/null', 'a+')
    se = file('/dev/null', 'a+', 0)
    os.dup2(si.fileno(), sys.stdin.fileno())
    os.dup2(so.fileno(), sys.stdout.fileno())
    os.dup2(se.fileno(), sys.stderr.fileno())

    if args.pidfile:
        try:
            atexit.register(delpid)
            pid = str(os.getpid())
            file(args.pidfile, 'w').write("%s\n" % pid)
        except IOError, e:
            raise SystemExit("Unable to write PID file: %s [%d]" % (e.strerror, e.errno))


def delpid():
    global args
    os.remove(args.pidfile)


def sighandler_shutdown(signum, frame):
    signal.signal(signal.SIGINT, signal.SIG_IGN)  # we heard you!
    cmdShutdown()

if __name__ == '__main__':
    signal.signal(signal.SIGINT, sighandler_shutdown)
    signal.signal(signal.SIGTERM, sighandler_shutdown)

    parser = argparse.ArgumentParser(description='PlexConnect as daemon.')
    parser.add_argument('--pidfile', dest='pidfile')
    args = parser.parse_args()

    daemonize(args)

    success = startup()

    if success:
        run()

        shutdown()