PyWireGate/daemon.py at master · OpenAutomationProject/PyWireGate · GitHub

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#!/usr/bin/env python

try:
importos
importsys
importtime
importatexit
importresource
fromsignalimportSIGTERM,SIGHUP
exceptStandardError, e:
importsys
print"Error while loading libraries: "
printe
sys.exit()

classDaemon(object):
"""
 A generic daemon class.

 Usage: subclass the Daemon class and override the run() method
 """
def__init__(self, pidfile, REDIRECTIO=True):
self.pidfile=pidfile
self.REDIRECTIO=REDIRECTIO


defdaemonize(self):
try:
pid=os.fork()
ifpid>0:
# exit first parent
time.sleep(.2)
os._exit(0)
exceptOSError, e:
sys.stderr.write("fork #1 failed: %d (%s)"% (e.errno, e.strerror))
sys.exit(1)

# decouple from parent environment
self.decouple()
os.setsid()

# do second fork
try:

pid=os.fork()
ifpid>0:
# exit from second parent, print eventual PID before
self.log("Daemon PID %d"%pid)
sys.stdout.flush()
os._exit(0)

exceptOSError, e:
sys.stderr.write("fork #2 failed: %d (%s)"% (e.errno, e.strerror))
os._exit(1)


sys.stdout.flush()
sys.stderr.flush()
## Cleanup
ifself.REDIRECTIO:
maxfd=resource.getrlimit(resource.RLIMIT_NOFILE)[1]
if (maxfd==resource.RLIM_INFINITY):
maxfd=1024
# close all file descriptors.
forfdinrange(0, maxfd):
try:
os.close(fd)
exceptOSError:	# ERROR, fd wasn't open to begin with (ignored)
pass

os.open(os.devnull, os.O_RDWR)	# standard input (0)
# Duplicate standard input to standard output and standard error.
os.dup2(0, 1) # standard output (1)
os.dup2(0, 2) # standard error (2)
self.writepid()


defwritepid(self):
pid=str(os.getpid())
file(self.pidfile,'w+').write("%s\n"%pid)


def__shutdown(self):
self.shutdown()
self.delpid()


defisdaemon(self):
"""Overried with isdaemon"""

defdelpid(self):
try:
os.remove(self.pidfile)
exceptOSError:
pass

defshutdown(self):
"""Override with shutdown"""

defreadpidfile(self):
try:
pf=file(self.pidfile,'r')
pid=int(pf.read().strip())
pf.close()
exceptIOError:
pid=None
returnpid

deflogrotate(self):
pid=self.readpidfile()
ifnotpid:
message="pidfile %s does not exist. Daemon not running?\n"
sys.stderr.write(message%self.pidfile)
return#
os.kill(pid,SIGHUP)

defstop(self):
pid=self.readpidfile()
ifnotpid:
message="pidfile %s does not exist. Daemon not running?\n"
sys.stderr.write(message%self.pidfile)
return# not an error in a restart

try:
while1:
os.kill(pid, SIGTERM)
time.sleep(0.1)
exceptOSError, err:
err=str(err)
iferr.find("No such process") >0:
ifos.path.exists(self.pidfile):
os.remove(self.pidfile)
else:
printstr(err)
sys.exit(1)

defrestart(self):
self.stop()
self.start()

defdecouple(self):
os.chdir("/")
os.setsid()
os.umask(0)

defstart(self,rundaemon=True):
try:
pf=file(self.pidfile,'r')
pid=int(pf.read().strip())
pf.close()
exceptIOError:
pid=None

ifpid:
try:
procfile=file("/proc/%d/status"%pid, 'r')
procfile.close()
exceptIOError:
self.delpid()
exceptTypeError:
self.delpid()
else:
message="pidfile %s already exist. Daemon already running?\n"
sys.stderr.write(message%self.pidfile)
sys.exit(1)
ifrundaemon:
self.daemonize()
else:
self.writepid()
self.decouple()


atexit.register(self.__shutdown)
self.isdaemon()
self.run()

defrun(self):
"""Override while subclassing"""