2 * This file is part of DisOrder.
3 * Copyright (C) 2004, 2005, 2008 Richard Kettlewell
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
20 /** @file server/daemonize.c
21 * @brief Go into background
33 #include "daemonize.h"
37 /** @brief Go into background
38 * @param tag Message tag, or NULL
39 * @param fac Logging facility
40 * @param pidfile Where to store PID, or NULL
42 * Become a daemon. stdout/stderr are lost and DisOrder's logging is
43 * redirected to syslog. It is assumed that there are no FDs beyond 2
46 void daemonize(const char *tag, int fac, const char *pidfile) {
51 D(("daemonize tag=%s fac=%d pidfile=%s",
52 tag ? tag : "NULL", fac, pidfile ? pidfile : "NULL"));
53 /* make sure that FDs 0, 1, 2 all at least exist (and get a
56 if((dn = open("/dev/null", O_RDWR, 0)) < 0)
57 fatal(errno, "error opening /dev/null");
61 /* Parent process. Wait for the first child to finish, then
62 * return to the caller. */
64 while((r = waitpid(pid, &w, 0)) == -1 && errno == EINTR)
66 if(r < 0) fatal(errno, "error calling waitpid");
67 if(w) error(0, "subprocess exited with wait status %#x", (unsigned)w);
70 /* First child process. This will be the session leader, and will
72 D(("first child pid=%lu", (unsigned long)getpid()));
73 if(setsid() < 0) fatal(errno, "error calling setsid");
74 /* we'll log to syslog */
75 openlog(tag, LOG_PID, fac);
76 log_default = &log_syslog;
77 /* stdin/out/err we lose */
85 /* second child. Write a pidfile if someone wanted it. */
86 D(("second child pid=%lu", (unsigned long)getpid()));
88 if(!(fp = fopen(pidfile, "w"))
89 || fprintf(fp, "%lu\n", (unsigned long)getpid()) < 0
91 fatal(errno, "error creating %s", pidfile);