lib/daemon.c

   1 /*
   2  * Daemonize routine
   3  * Copyright (C) 1997, 1999 Kunihiro Ishiguro
   4  *
   5  * This file is part of GNU Zebra.
   6  *
   7  * GNU Zebra is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published
   9  * by the Free Software Foundation; either version 2, or (at your
  10  * option) any later version.
  11  *
  12  * GNU Zebra is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with GNU Zebra; see the file COPYING.  If not, write to the
  19  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20  * Boston, MA 02111-1307, USA.
  21  */
  22
  23 #include <zebra.h>
  24
  25 #ifndef HAVE_DAEMON
  26
  27 /* Daemonize myself. */
  28 int
  29 daemon (int nochdir, int noclose)
  30 {
  31   pid_t pid;
  32
  33   pid = fork ();
  34
  35   /* In case of fork is error. */
  36   if (pid < 0)
  37     {
  38       zlog_err ("fork failed: %s", safe_strerror(errno));
  39       return -1;
  40     }
  41
  42   /* In case of this is parent process. */
  43   if (pid != 0)
  44     exit (0);
  45
  46   /* Become session leader and get pid. */
  47   pid = setsid();
  48
  49   if (pid == -1)
  50     {
  51       zlog_err ("setsid failed: %s", safe_strerror(errno));
  52       return -1;
  53     }
  54
  55   /* Change directory to root. */
  56   if (! nochdir)
  57     chdir ("/");
  58
  59   /* File descriptor close. */
  60   if (! noclose)
  61     {
  62       int fd;
  63
  64       fd = open ("/dev/null", O_RDWR, 0);
  65       if (fd != -1)
  66         {
  67           dup2 (fd, STDIN_FILENO);
  68           dup2 (fd, STDOUT_FILENO);
  69           dup2 (fd, STDERR_FILENO);
  70           if (fd > 2)
  71             close (fd);
  72         }
  73     }
  74
  75   umask (0027);
  76
  77   return 0;
  78 }
  79
  80 #endif /* HAVE_DAEMON */