blob: 15a7c05e95b878ad6cf7c25905376c8fc8613683 [file] [log] [blame]
Bernhard Reutner-Fischerc89982d2006-06-03 19:49:21 +00001/* vi: set sw=4 ts=4: */
Paul Fox42403642005-08-01 22:52:09 +00002/*
3 * setsid.c -- execute a command in a new session
4 * Rick Sladkey <jrs@world.std.com>
5 * In the public domain.
6 *
Denis Vlasenkob44c7902008-03-17 09:29:43 +00007 * 1999-02-22 Arkadiusz Mickiewicz <misiek@pld.ORG.PL>
Paul Fox42403642005-08-01 22:52:09 +00008 * - added Native Language Support
9 *
10 * 2001-01-18 John Fremlin <vii@penguinpowered.com>
11 * - fork in case we are process group leader
12 *
13 * 2004-11-12 Paul Fox
14 * - busyboxed
15 */
Denys Vlasenkofb4da162016-11-22 23:14:24 +010016//config:config SETSID
Denys Vlasenko4eed2c62017-07-18 22:01:24 +020017//config: bool "setsid (3.9 kb)"
Denys Vlasenkofb4da162016-11-22 23:14:24 +010018//config: default y
19//config: help
20//config: setsid runs a program in a new session
Paul Fox42403642005-08-01 22:52:09 +000021
Denys Vlasenkof88e3bf2016-11-22 23:54:17 +010022//applet:IF_SETSID(APPLET(setsid, BB_DIR_USR_BIN, BB_SUID_DROP))
23
24//kbuild:lib-$(CONFIG_SETSID) += setsid.o
25
Pere Orga5bc8c002011-04-11 03:29:49 +020026//usage:#define setsid_trivial_usage
Denys Vlasenkoccf7f0e2016-01-17 01:09:36 +010027//usage: "[-c] PROG ARGS"
Pere Orga5bc8c002011-04-11 03:29:49 +020028//usage:#define setsid_full_usage "\n\n"
29//usage: "Run PROG in a new session. PROG will have no controlling terminal\n"
Denys Vlasenkoccf7f0e2016-01-17 01:09:36 +010030//usage: "and will not be affected by keyboard signals (^C etc).\n"
31//usage: "\n -c Set controlling terminal to stdin"
Pere Orga5bc8c002011-04-11 03:29:49 +020032
Denis Vlasenkob6adbf12007-05-26 19:00:18 +000033#include "libbb.h"
Paul Fox42403642005-08-01 22:52:09 +000034
Denis Vlasenko9b49a5e2007-10-11 10:05:36 +000035int setsid_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
Denis Vlasenkoa60f84e2008-07-05 09:18:54 +000036int setsid_main(int argc UNUSED_PARAM, char **argv)
Mike Frysingere1d41b32006-03-23 02:07:41 +000037{
Denys Vlasenkoccf7f0e2016-01-17 01:09:36 +010038 unsigned opt;
39
40 opt_complementary = "-1"; /* at least one arg */
Denys Vlasenko7cf45ae2016-06-20 23:50:26 +020041 opt = getopt32(argv, "+c"); /* +: stop on first non-opt */
Denys Vlasenkoccf7f0e2016-01-17 01:09:36 +010042 argv += optind;
Paul Fox42403642005-08-01 22:52:09 +000043
Denis Vlasenkob44c7902008-03-17 09:29:43 +000044 /* setsid() is allowed only when we are not a process group leader.
45 * Otherwise our PID serves as PGID of some existing process group
Denys Vlasenkoa5e6c6c2013-08-07 18:49:51 +020046 * and cannot be used as PGID of a new process group.
47 *
48 * Example: setsid() below fails when run alone in interactive shell:
49 * $ setsid PROG
50 * because shell's child (setsid) is put in a new process group.
51 * But doesn't fail if shell is not interactive
52 * (and therefore doesn't create process groups for pipes),
53 * or if setsid is not the first process in the process group:
54 * $ true | setsid PROG
55 * or if setsid is executed in backquotes (`setsid PROG`)...
56 */
Denys Vlasenkoa29b0552010-05-16 02:12:56 +020057 if (setsid() < 0) {
58 pid_t pid = fork_or_rexec(argv);
59 if (pid != 0) {
60 /* parent */
61 /* TODO:
62 * we can waitpid(pid, &status, 0) and then even
63 * emulate exitcode, making the behavior consistent
64 * in both forked and non forked cases.
65 * However, the code is larger and upstream
66 * does not do such trick.
67 */
Denys Vlasenkoa5e6c6c2013-08-07 18:49:51 +020068 return EXIT_SUCCESS;
Denys Vlasenkoa29b0552010-05-16 02:12:56 +020069 }
Paul Fox42403642005-08-01 22:52:09 +000070
Denys Vlasenkoa29b0552010-05-16 02:12:56 +020071 /* child */
72 /* now there should be no error: */
73 setsid();
74 }
Paul Fox42403642005-08-01 22:52:09 +000075
Denys Vlasenkoccf7f0e2016-01-17 01:09:36 +010076 if (opt) {
77 /* -c: set (with stealing) controlling tty */
78 ioctl(0, TIOCSCTTY, 1);
79 }
80
Pascal Bellard21e8e8d2010-07-04 00:57:03 +020081 BB_EXECVP_or_die(argv);
Paul Fox42403642005-08-01 22:52:09 +000082}