import os import sys from . import six buffering = int(six.PY3) # No unbuffered text I/O on Python 3 (#20815). if os.name == 'posix': def become_daemon(our_home_dir='.', out_log='/dev/null', err_log='/dev/null', umask=0o022): "Robustly turn into a UNIX daemon, running in our_home_dir." # First fork try: if os.fork() > 0: sys.exit(0) # kill off parent except OSError as e: sys.stderr.write("fork #1 failed: (%d) %s\n" % (e.errno, e.strerror)) sys.exit(1) os.setsid() os.chdir(our_home_dir) os.umask(umask) # Second fork try: if os.fork() > 0: os._exit(0) except OSError as e: sys.stderr.write("fork #2 failed: (%d) %s\n" % (e.errno, e.strerror)) os._exit(1) si = open('/dev/null', 'r') so = open(out_log, 'a+', buffering) se = open(err_log, 'a+', buffering) os.dup2(si.fileno(), sys.stdin.fileno()) os.dup2(so.fileno(), sys.stdout.fileno()) os.dup2(se.fileno(), sys.stderr.fileno()) # Set custom file descriptors so that they get proper buffering. sys.stdout, sys.stderr = so, se else: def become_daemon(our_home_dir='.', out_log=None, err_log=None, umask=0o022): """ If we're not running under a POSIX system, just simulate the daemon mode by doing redirections and directory changing. """ os.chdir(our_home_dir) os.umask(umask) sys.stdin.close() sys.stdout.close() sys.stderr.close() if err_log: sys.stderr = open(err_log, 'a', buffering) else: sys.stderr = NullDevice() if out_log: sys.stdout = open(out_log, 'a', buffering) else: sys.stdout = NullDevice() class NullDevice: "A writeable object that writes to nowhere -- like /dev/null." def write(self, s): pass