X-Git-Url: https://git.kaliko.me/?p=python-daemon.git;a=blobdiff_plain;f=seth.py;fp=seth.py;h=cfc5ed421ed1fb235c361ad385cd6eda63ab499d;hp=0000000000000000000000000000000000000000;hb=93b04564dae8bf7fc8c5e47c404698222ee039de;hpb=43f9a47ada69104b79a759a56ff6706945503ec2

diff --git a/seth.py b/seth.py
new file mode 100644
index 0000000..cfc5ed4
--- /dev/null
+++ b/seth.py
@@ -0,0 +1,198 @@
+# -*- coding: utf-8 -*-
+
+# Public Domain
+#
+# Copyright 2007, 2009 Sander Marechal <s.marechal@jejik.com>
+# Copyright 2010, 2011, 2012 Jack Kaliko <kaliko@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 = "0.5"
+
+    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