1 /* nbdkit
2 * Copyright (C) 2019-2020 Red Hat Inc.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *
11 * * Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * * Neither the name of Red Hat nor the names of its contributors may be
16 * used to endorse or promote products derived from this software without
17 * specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
21 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
22 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
26 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
27 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
28 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
29 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include <config.h>
34
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <stdarg.h>
38 #include <string.h>
39 #include <unistd.h>
40 #include <fcntl.h>
41
42 #include "internal.h"
43
44 /* True if we forked into the background (used to control log messages). */
45 bool forked_into_background;
46
47 /* Run as a background process. If foreground is set (ie. -f or
48 * equivalent) then this does nothing. Otherwise it forks into the
49 * background and sets forked_into_background.
50 */
51 void
fork_into_background(void)52 fork_into_background (void)
53 {
54 pid_t pid;
55
56 if (foreground)
57 return;
58
59 pid = fork ();
60 if (pid == -1) {
61 perror ("fork");
62 exit (EXIT_FAILURE);
63 }
64
65 if (pid > 0) /* Parent process exits. */
66 exit (EXIT_SUCCESS);
67
68 #pragma GCC diagnostic push
69 #pragma GCC diagnostic ignored "-Wunused-result"
70 chdir ("/");
71 #pragma GCC diagnostic pop
72
73 /* By this point, stdin/out have been redirected to /dev/null.
74 * If not verbose, set stderr to the same as stdout as well.
75 */
76 if (!verbose)
77 dup2 (STDOUT_FILENO, STDERR_FILENO);
78
79 forked_into_background = true;
80 debug ("forked into background (new pid = %d)", getpid ());
81 }
82