xenu_nntp/lib/nntp/tiny/daemon.py

import os
import signal
import configparser

from nntp.tiny.config import (ConfigSectionException,
                              ConfigValueException)

class Daemon():
    def init(config: configparser.ConfigParser):
        if not config.has_section('daemon'):
            raise ConfigSectionException('daemon')

        if not config.has_option('daemon', 'pidfile'):
            raise ConfigValueException('daemon', 'pidfile')

        pidfile = config.get('daemon', 'pidfile')

        pid = os.fork()

        if pid > 0:
            exit(0)

        with open(pidfile, 'w') as fh:
            print(str(os.getpid()), file=fh)

        def stop(sig, trace):
            os.unlink(pidfile)
            exit(0)

        signal.signal(signal.SIGTERM, stop)