app/django/utils/daemonize.py
author Daniel Bentley <dbentley@google.com>
Wed, 15 Apr 2009 08:01:17 +0000
changeset 2184 a1bda9afa5d0
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Step 2 of moving to new seeding model. Create Seeder class, which abstracts some seeding. Move user to Seeder class, and make new OrganizationSeeder class. If people like this, I'll finish the rest soon. Patch by: Dan Bentley

import os
import sys

if os.name == 'posix':
    def become_daemon(our_home_dir='.', out_log='/dev/null',
                      err_log='/dev/null', umask=022):
        "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, 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, 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+', 0)
        se = open(err_log, 'a+', 0)
        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=022):
        """
        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', 0)
        else:
            sys.stderr = NullDevice()
        if out_log:
            sys.stdout = open(out_log, 'a', 0)
        else:
            sys.stdout = NullDevice()

    class NullDevice:
        "A writeable object that writes to nowhere -- like /dev/null."
        def write(self, s):
            pass