1 files changed, 122 insertions, 0 deletions
diff --git a/python/daemon.py b/python/daemon.py
new file mode 100644
index 00000000..cb2c6bd3
--- /dev/null
+++ b/python/daemon.py
@@ -0,0 +1,122 @@
+"""Generic linux daemon base class for python 3.x."""
+
+import sys, os, time, atexit, signal
+
+class daemon:
+	"""A generic daemon class.
+
+	Usage: subclass the daemon class and override the run() method."""
+
+	def __init__(self, pidfile): self.pidfile = pidfile
+	
+	def daemonize(self):
+		"""Deamonize class. UNIX double fork mechanism."""
+
+		try: 
+			pid = os.fork() 
+			if pid > 0:
+				# exit first parent
+				sys.exit(0) 
+		except OSError as err: 
+			sys.stderr.write('fork #1 failed: {0}\n'.format(err))
+			sys.exit(1)
+	
+		# decouple from parent environment
+		os.chdir('/') 
+		os.setsid() 
+		os.umask(0) 
+	
+		# do second fork
+		try: 
+			pid = os.fork() 
+			if pid > 0:
+
+				# exit from second parent
+				sys.exit(0) 
+		except OSError as err: 
+			sys.stderr.write('fork #2 failed: {0}\n'.format(err))
+			sys.exit(1) 
+	
+		# redirect standard file descriptors
+		sys.stdout.flush()
+		sys.stderr.flush()
+		si = open(os.devnull, 'r')
+		so = open(os.devnull, 'a+')
+		se = open(os.devnull, 'a+')
+
+		os.dup2(si.fileno(), sys.stdin.fileno())
+		os.dup2(so.fileno(), sys.stdout.fileno())
+		os.dup2(se.fileno(), sys.stderr.fileno())
+	
+		# write pidfile
+		atexit.register(self.delpid)
+
+		pid = str(os.getpid())
+		with open(self.pidfile,'w+') as f:
+			f.write(pid + '\n')
+	
+	def delpid(self):
+		os.remove(self.pidfile)
+
+	def start(self):
+		"""Start the daemon."""
+
+		# Check for a pidfile to see if the daemon already runs
+		try:
+			with open(self.pidfile,'r') as pf:
+
+				pid = int(pf.read().strip())
+		except IOError:
+			pid = None
+	
+		if pid:
+			message = "pidfile {0} already exist. " + \
+					"Daemon already running?\n"
+			sys.stderr.write(message.format(self.pidfile))
+			sys.exit(1)
+		
+		# Start the daemon
+		self.daemonize()
+		self.run()
+
+	def stop(self):
+		"""Stop the daemon."""
+
+		# Get the pid from the pidfile
+		try:
+			with open(self.pidfile,'r') as pf:
+				pid = int(pf.read().strip())
+		except IOError:
+			pid = None
+	
+		if not pid:
+			message = "pidfile {0} does not exist. " + \
+					"Daemon not running?\n"
+			sys.stderr.write(message.format(self.pidfile))
+			return # not an error in a restart
+
+		# Try killing the daemon process	
+		try:
+			while 1:
+				os.kill(pid, signal.SIGTERM)
+				time.sleep(0.1)
+		except OSError as err:
+			e = str(err.args)
+			if e.find("No such process") > 0:
+				if os.path.exists(self.pidfile):
+					os.remove(self.pidfile)
+			else:
+				print (str(err.args))
+				sys.exit(1)
+
+	def restart(self):
+		"""Restart the daemon."""
+		self.stop()
+		self.start()
+
+	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()."""
+