+++ /dev/null
-# -*- coding: utf-8 -*-
-
-# Public Domain
-#
-# Copyright 2007, 2009 Sander Marechal <s.marechal@jejik.com>
-# Copyright 2010, 2011, 2012 Jack Kaliko <efrim@azylum.org>
-#
-# http://www.jejik.com/articles/2007/02/a_simple_unix_linux_daemon_in_python/
-
-import atexit
-import os
-import sys
-import time
-from signal import signal, SIGTERM
-
-
-class Daemon(object):
- """
- A generic daemon class.
-
- Usage: subclass the Daemon class and override the run() method
- """
- version = "0.4"
-
- def __init__(self, pidfile,
- stdin='/dev/null',
- stdout='/dev/null',
- stderr='/dev/null'):
- self.stdin = stdin
- self.stdout = stdout
- self.stderr = stderr
- self.pidfile = pidfile
- self.umask = 0
-
- def daemonize(self):
- """
- Do the UNIX double-fork magic.
- see W. Richard Stevens, "Advanced Programming in the Unix Environment"
- for details (ISBN 0201563177)
-
- Short explanation:
- Unix processes belong to "process group" which in turn lies within a "session".
- A session can have a controlling tty.
- Forking twice allows to detach the session from a possible tty.
- The process lives then within the init process.
- """
- try:
- pid = os.fork()
- if pid > 0:
- # exit first parent
- sys.exit(0)
- except OSError, e:
- sys.stderr.write('fork #1 failed: %d (%s)\n' % (e.errno, e.strerror))
- sys.exit(1)
-
- # Decouple from parent environment
- os.chdir('/')
- os.setsid()
- self.umask = os.umask(0)
-
- # Do second fork
- try:
- pid = os.fork()
- if pid > 0:
- # exit from second parent
- sys.exit(0)
- except OSError, e:
- sys.stderr.write('fork #2 failed: %d (%s)\n' % (e.errno, e.strerror))
- sys.exit(1)
-
- self.write_pid()
- # redirect standard file descriptors
- sys.stdout.flush()
- sys.stderr.flush()
- si = file(self.stdin, 'r')
- so = file(self.stdout, 'a+')
- se = file(self.stderr, 'a+', 0)
- os.dup2(si.fileno(), sys.stdin.fileno())
- os.dup2(so.fileno(), sys.stdout.fileno())
- os.dup2(se.fileno(), sys.stderr.fileno())
-
- atexit.register(self.shutdown)
- self.signal_management()
-
- def write_pid(self):
- # write pidfile
- if not self.pidfile:
- return
- pid = str(os.getpid())
- try:
- os.umask(self.umask)
- file(self.pidfile, 'w').write('%s\n' % pid)
- except Exception, wpid_err:
- sys.stderr.write(u'Error trying to write pid file: %s\n' % wpid_err)
- sys.exit(1)
- os.umask(0)
- atexit.register(self.delpid)
-
- def signal_management(self):
- # Declare signal handlers
- signal(SIGTERM, self.exit_handler)
-
- def exit_handler(self, signum, frame):
- sys.exit(1)
-
- def delpid(self):
- try:
- os.unlink(self.pidfile)
- except OSError as err:
- message = 'Error trying to remove PID file: %s\n'
- sys.stderr.write(message % err)
-
- def start(self):
- """
- Start the daemon
- """
- # Check for a pidfile to see if the daemon already runs
- try:
- pf = file(self.pidfile, 'r')
- pid = int(pf.read().strip())
- pf.close()
- except IOError:
- pid = None
-
- if pid:
- message = 'pidfile %s already exist. Daemon already running?\n'
- sys.stderr.write(message % self.pidfile)
- sys.exit(1)
-
- # Start the daemon
- self.daemonize()
- self.run()
-
- def foreground(self):
- """
- Foreground/debug mode
- """
- self.write_pid()
- atexit.register(self.shutdown)
- self.run()
-
- def stop(self):
- """
- Stop the daemon
- """
- # Get the pid from the pidfile
- try:
- pf = file(self.pidfile, 'r')
- pid = int(pf.read().strip())
- pf.close()
- except IOError:
- pid = None
-
- if not pid:
- message = 'pidfile %s does not exist. Is the Daemon running?\n'
- sys.stderr.write(message % self.pidfile)
- return # not an error in a restart
-
- # Try killing the daemon process
- try:
- os.kill(pid, SIGTERM)
- time.sleep(0.1)
- except OSError, err:
- if err.errno == 3:
- if os.path.exists(self.pidfile):
- message = "Daemon's not running? removing pid file %s.\n"
- sys.stderr.write(message % self.pidfile)
- os.remove(self.pidfile)
- else:
- sys.stderr.write(err.strerror)
- sys.exit(1)
-
- def restart(self):
- """
- Restart the daemon
- """
- self.stop()
- self.start()
-
- def shutdown(self):
- """
- You should override this method when you subclass Daemon. It will be
- called when the process is being stopped.
- Pay attention:
- Daemon() uses atexit to call Daemon().shutdown(), as a consequence
- shutdown and any other functions registered via this module are not
- called when the program is killed by an un-handled/unknown signal.
- This is the reason of Daemon().signal_management() existence.
- """
-
- def run(self):
- """
- You should override this method when you subclass Daemon. It will be
- called after the process has been daemonized by start() or restart().
- """
-
-# VIM MODLINE
-# vim: ai ts=4 sw=4 sts=4 expandtab
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