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"""Generic linux daemon base class"""
# Adapted from http://www.jejik.com/files/examples/daemon3x.py
# thanks to the original author
import sys
import os
import time
import atexit
import signal
import syslog
import psutil
class Daemon(object):
"""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()
stdi = open(os.devnull, 'r')
stdo = open(os.devnull, 'a+')
stde = open(os.devnull, 'a+')
os.dup2(stdi.fileno(), sys.stdin.fileno())
os.dup2(stdo.fileno(), sys.stdout.fileno())
os.dup2(stde.fileno(), sys.stderr.fileno())
# write pidfile
atexit.register(self.delpid)
pid = str(os.getpid())
with open(self.pidfile, 'w+') as fd:
fd.write(pid + '\n')
def delpid(self):
"""Delete pid file"""
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 pidf:
pid = int(pidf.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()
syslog.syslog(syslog.LOG_INFO, '{}: started'.format(os.path.basename(sys.argv[0])))
while True:
# look if steam is running
if len([p for p in psutil.process_iter() if p.name() == 'steam']) == 0:
try:
self.run()
except Exception as e: # pylint: disable=W0703
syslog.syslog(syslog.LOG_ERR, '{}: {!s}'.format(os.path.basename(sys.argv[0]), e))
else:
syslog.syslog(syslog.LOG_INFO, '{}: steam client is runing'.format(os.path.basename(sys.argv[0])))
time.sleep(2)
def stop(self):
"""Stop the daemon."""
# Get the pid from the pidfile
try:
with open(self.pidfile, 'r') as pidf:
pid = int(pidf.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 True:
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)
syslog.syslog(syslog.LOG_INFO, '{}: stopped'.format(os.path.basename(sys.argv[0])))
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()."""
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