git.maemo.org Git - dbuscron/blob - dbuscron/util.py

   1 import os, sys
   2
   3 def daemonize(logfile=None, errfile=None, pidfile=None):
   4     devnull = os.devnull if hasattr(os, 'devnull') else '/dev/null'
   5
   6     initwd = os.getcwd()
   7
   8     def absolutize(path):
   9         if path.startswith('/'):
  10             return path
  11         return os.path.join(initwd, path)
  12
  13     try:
  14         if os.fork() == 0:
  15             os.setsid()
  16             if os.fork() == 0:
  17                 os.chdir('/')
  18                 os.umask(0)
  19             else:
  20                 os._exit(0)
  21         else:
  22             os._exit(0)
  23     except OSError, e:
  24         raise SystemError('Failed daemonization: %s' % str(e))
  25
  26     for i in range(0, 3):
  27         os.close(i)
  28
  29     os.open(devnull, os.O_RDWR)
  30
  31     def open_trunc(fname):
  32         f = os.open(fname, os.O_WRONLY | os.O_CREAT)
  33         os.ftruncate(f, 0)
  34         return f
  35
  36     def open_or_dup(fname, fd=None):
  37         if fname:
  38             return open_trunc(absolutize(fname))
  39         elif fd:
  40             os.dup2(*fd)
  41
  42     open_or_dup(logfile, (0, 1))
  43     open_or_dup(errfile, (1, 2))
  44
  45     pid = os.getpid()
  46     if pidfile:
  47         pidfile = absolutize(pidfile)
  48         fd = open_trunc(pidfile)
  49         os.write(fd, str(pid))
  50         os.close(fd)
  51
  52         def remove_pidfile():
  53             os.unlink(pidfile)
  54         sys.exitfunc = remove_pidfile
  55
  56     return pid
  57
  58 def set_user_and_group(user, group=None):
  59     if os.getuid() != 0:
  60         raise SystemError('I\'m not a root to pretend somebody else.')
  61
  62     if user:
  63         import pwd
  64         try:
  65             userid = int(user)
  66         except ValueError:
  67             userid = pwd.getpwnam(user)[2]
  68
  69     else:
  70         userid = None
  71
  72     if group:
  73         try:
  74             groupid = int(group)
  75         except ValueError:
  76             import grp
  77             groupid = grp.getgrnam(group)[2]
  78
  79     elif userid:
  80         groupid = pwd.getpwuid(userid)[3]
  81
  82     else:
  83         groupid = None
  84
  85     if groupid:
  86         os.setgid(groupid)
  87     if userid:
  88         os.setuid(userid)
  89