libite 2.6.1
runbg.c
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1/* Run a command in the background: fork() + usleep() + execvp()
2 *
3 * Copyright (c) 2023 Joachim Wiberg <troglobit@gmail.com>
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
24
25#include <errno.h>
26#include <sys/types.h>
27#include <sys/wait.h>
28#include <unistd.h>
29
46int runbg(char *const cmd[], int delay)
47{
48 int pid = fork();
49 int rc;
50
51 if (!pid) {
52 int fd, maxfd;
53
54 if (setsid() == -1)
55 _exit(errno);
56
57 /* reparent to init */
58 pid = fork();
59 if (pid == -1)
60 _exit(errno);
61 if (pid > 0)
62 _exit(0);
63
64 maxfd = sysconf(_SC_OPEN_MAX);
65 if (maxfd == -1)
66 maxfd = 8192;
67 for (fd = 0; fd < maxfd; fd++)
68 close(fd);
69
70 usleep(delay);
71 _exit(execvp(cmd[0], cmd));
72 }
73
74 if (pid == -1)
75 return -1;
76
77 if (waitpid(pid, &rc, 0) == -1)
78 return -1;
79
80 if (WIFEXITED(rc)) {
81 errno = WEXITSTATUS(rc);
82 if (errno)
83 rc = -1;
84 else
85 rc = 0;
86 } else if (WIFSIGNALED(rc)) {
87 errno = EINTR;
88 rc = -1;
89 } else
90 rc = -1;
91
92 return rc;
93}
int runbg(char *const cmd[], int delay)
Definition runbg.c:46