chiark / gitweb /
Linux build fix
[disorder] / server / daemonize.c
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460b9539 1/*
2 * This file is part of DisOrder.
5aff007d 3 * Copyright (C) 2004, 2005, 2007, 2008 Richard Kettlewell
460b9539 4 *
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.
9 *
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.
14 *
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
18 * USA
19 */
0590cedc
RK
20/** @file server/daemonize.c
21 * @brief Go into background
22 */
460b9539 23
05b75f8d 24#include "disorder-server.h"
460b9539 25
0590cedc
RK
26/** @brief Go into background
27 * @param tag Message tag, or NULL
28 * @param fac Logging facility
29 * @param pidfile Where to store PID, or NULL
30 *
31 * Become a daemon. stdout/stderr are lost and DisOrder's logging is
32 * redirected to syslog. It is assumed that there are no FDs beyond 2
33 * that need closing.
34 */
460b9539 35void daemonize(const char *tag, int fac, const char *pidfile) {
36 pid_t pid, r;
37 int w, dn;
38 FILE *fp;
39
40 D(("daemonize tag=%s fac=%d pidfile=%s",
41 tag ? tag : "NULL", fac, pidfile ? pidfile : "NULL"));
42 /* make sure that FDs 0, 1, 2 all at least exist (and get a
43 * /dev/null) */
44 do {
45 if((dn = open("/dev/null", O_RDWR, 0)) < 0)
46 fatal(errno, "error opening /dev/null");
47 } while(dn < 3);
48 pid = xfork();
49 if(pid) {
50 /* Parent process. Wait for the first child to finish, then
51 * return to the caller. */
52 exitfn = _exit;
53 while((r = waitpid(pid, &w, 0)) == -1 && errno == EINTR)
54 ;
55 if(r < 0) fatal(errno, "error calling waitpid");
56 if(w) error(0, "subprocess exited with wait status %#x", (unsigned)w);
57 _exit(0);
58 }
59 /* First child process. This will be the session leader, and will
60 * be transient. */
61 D(("first child pid=%lu", (unsigned long)getpid()));
62 if(setsid() < 0) fatal(errno, "error calling setsid");
63 /* we'll log to syslog */
64 openlog(tag, LOG_PID, fac);
65 log_default = &log_syslog;
66 /* stdin/out/err we lose */
67 xdup2(dn, 0);
68 xdup2(dn, 1);
69 xdup2(dn, 2);
70 xclose(dn);
71 pid = xfork();
72 if(pid)
73 _exit(0);
74 /* second child. Write a pidfile if someone wanted it. */
75 D(("second child pid=%lu", (unsigned long)getpid()));
76 if(pidfile) {
77 if(!(fp = fopen(pidfile, "w"))
78 || fprintf(fp, "%lu\n", (unsigned long)getpid()) < 0
79 || fclose(fp) < 0)
80 fatal(errno, "error creating %s", pidfile);
81 }
82}
83
84/*
85Local Variables:
86c-basic-offset:2
87comment-column:40
88End:
89*/