| 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * setsid.c -- execute a command in a new session
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| 4 | * Rick Sladkey <jrs@world.std.com>
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| 5 | * In the public domain.
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| 6 | *
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| 7 | * 1999-02-22 Arkadiusz Mickiewicz <misiek@pld.ORG.PL>
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| 8 | * - added Native Language Support
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| 9 | *
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| 10 | * 2001-01-18 John Fremlin <vii@penguinpowered.com>
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| 11 | * - fork in case we are process group leader
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| 12 | *
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| 13 | * 2004-11-12 Paul Fox
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| 14 | * - busyboxed
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| 15 | */
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| 16 |
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| 17 | //usage:#define setsid_trivial_usage
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| 18 | //usage: "[-c] PROG ARGS"
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| 19 | //usage:#define setsid_full_usage "\n\n"
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| 20 | //usage: "Run PROG in a new session. PROG will have no controlling terminal\n"
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| 21 | //usage: "and will not be affected by keyboard signals (^C etc).\n"
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| 22 | //usage: "\n -c Set controlling terminal to stdin"
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| 23 |
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| 24 | #include "libbb.h"
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| 25 |
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| 26 | int setsid_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 27 | int setsid_main(int argc UNUSED_PARAM, char **argv)
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| 28 | {
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| 29 | unsigned opt;
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| 30 |
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| 31 | opt_complementary = "-1"; /* at least one arg */
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| 32 | opt = getopt32(argv, "+c"); /* +: stop on first non-opt */
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| 33 | argv += optind;
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| 34 |
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| 35 | /* setsid() is allowed only when we are not a process group leader.
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| 36 | * Otherwise our PID serves as PGID of some existing process group
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| 37 | * and cannot be used as PGID of a new process group.
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| 38 | *
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| 39 | * Example: setsid() below fails when run alone in interactive shell:
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| 40 | * $ setsid PROG
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| 41 | * because shell's child (setsid) is put in a new process group.
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| 42 | * But doesn't fail if shell is not interactive
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| 43 | * (and therefore doesn't create process groups for pipes),
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| 44 | * or if setsid is not the first process in the process group:
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| 45 | * $ true | setsid PROG
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| 46 | * or if setsid is executed in backquotes (`setsid PROG`)...
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| 47 | */
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| 48 | if (setsid() < 0) {
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| 49 | pid_t pid = fork_or_rexec(argv);
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| 50 | if (pid != 0) {
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| 51 | /* parent */
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| 52 | /* TODO:
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| 53 | * we can waitpid(pid, &status, 0) and then even
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| 54 | * emulate exitcode, making the behavior consistent
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| 55 | * in both forked and non forked cases.
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| 56 | * However, the code is larger and upstream
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| 57 | * does not do such trick.
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| 58 | */
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| 59 | return EXIT_SUCCESS;
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| 60 | }
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| 61 |
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| 62 | /* child */
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| 63 | /* now there should be no error: */
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| 64 | setsid();
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| 65 | }
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| 66 |
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| 67 | if (opt) {
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| 68 | /* -c: set (with stealing) controlling tty */
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| 69 | ioctl(0, TIOCSCTTY, 1);
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| 70 | }
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| 71 |
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| 72 | BB_EXECVP_or_die(argv);
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| 73 | }
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