--- /dev/null
+# -*- coding: utf-8 -*-
+
+# Public Domain
+#
+# Copyright 2007, 2009 Sander Marechal <s.marechal@jejik.com>
+# http://www.jejik.com/articles/2007/02/a_simple_unix_linux_daemon_in_python/
+#
+# Copyright 2010, 2011 Jack Kaliko <efrim@azylum.org>
+# https://gitorious.org/python-daemon
+#
+# This file is part of MPD_sima
+#
+# MPD_sima is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# MPD_sima is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with MPD_sima. If not, see <http://www.gnu.org/licenses/>.
+
+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
+
+ Daemon([pidfile[, stdin[, stdout[, stderr]]]])
+
+ pidfile : file to write pid to (default no pid file writen)
+ stdin : standard input file descriptor (default to /dev/null)
+ stdout : standard output file descriptor (default to /dev/null)
+ stderr : standard error file descriptorr (default to /dev/null)
+ """
+ version = '0.6'
+
+ def __init__(self, pidfile,
+ stdin = os.devnull,
+ stdout = os.devnull,
+ stderr = os.devnull):
+ 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 as e:
+ sys.stderr.write('fork #1 failed: {0.errno:d} ({0.strerror})\n'.format(e))
+ 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 as e:
+ sys.stderr.write('fork #2 failed: {0.errno:d} ({0.strerror})\n'.format(e))
+ sys.exit(1)
+
+ self.write_pid()
+ # redirect standard file descriptors
+ sys.stdout.flush()
+ sys.stderr.flush()
+ # TODO: binary or txt mode?
+ si = open(self.stdin, mode='rb')
+ so = open(self.stdout, mode='ab+')
+ se = open(self.stderr, mode='ab+', buffering=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)
+ open(self.pidfile, 'w').write('%s\n' % pid)
+ except Exception as wpid_err:
+ sys.stderr.write('Error trying to write pid file: {}\n'.format(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):
+ """Remove PID file"""
+ try:
+ os.unlink(self.pidfile)
+ except OSError as err:
+ message = 'Error trying to remove PID file: {}\n'
+ sys.stderr.write(message.format(err))
+
+ def start(self):
+ """
+ Start the daemon
+ """
+ # Check for a pidfile to see if the daemon already runs
+ try:
+ pf = open(self.pidfile, 'r')
+ pid = int(pf.read().strip())
+ pf.close()
+ except IOError:
+ pid = None
+
+ if pid:
+ message = 'pidfile {0.pidfile} already exist. Daemon already running?\n'
+ sys.stderr.write(message.format(self))
+ 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 = open(self.pidfile, 'r')
+ pid = int(pf.read().strip())
+ pf.close()
+ except IOError:
+ pid = None
+
+ if not pid:
+ message = 'pidfile {0.pidfile} does not exist. Is the Daemon running?\n'
+ sys.stderr.write(message.format(self))
+ return # not an error in a restart
+
+ # Try killing the daemon process
+ try:
+ os.kill(pid, SIGTERM)
+ time.sleep(0.1)
+ except OSError as err:
+ if err.errno == 3:
+ if os.path.exists(self.pidfile):
+ message = "Daemon's not running? removing pid file {0.pidfile}.\n"
+ sys.stderr.write(message.format(self))
+ 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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