blob: 143a8f8fa60e317fdb59a0a85f18042d6c78406a
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * setsid.c -- execute a command in a new session |
4 | * Rick Sladkey <jrs@world.std.com> |
5 | * In the public domain. |
6 | * |
7 | * 1999-02-22 Arkadiusz Mickiewicz <misiek@pld.ORG.PL> |
8 | * - 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 | */ |
16 | //config:config SETSID |
17 | //config: bool "setsid" |
18 | //config: default y |
19 | //config: help |
20 | //config: setsid runs a program in a new session |
21 | |
22 | //applet:IF_SETSID(APPLET(setsid, BB_DIR_USR_BIN, BB_SUID_DROP)) |
23 | |
24 | //kbuild:lib-$(CONFIG_SETSID) += setsid.o |
25 | |
26 | //usage:#define setsid_trivial_usage |
27 | //usage: "[-c] PROG ARGS" |
28 | //usage:#define setsid_full_usage "\n\n" |
29 | //usage: "Run PROG in a new session. PROG will have no controlling terminal\n" |
30 | //usage: "and will not be affected by keyboard signals (^C etc).\n" |
31 | //usage: "\n -c Set controlling terminal to stdin" |
32 | |
33 | #include "libbb.h" |
34 | |
35 | int setsid_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
36 | int setsid_main(int argc UNUSED_PARAM, char **argv) |
37 | { |
38 | unsigned opt; |
39 | |
40 | opt_complementary = "-1"; /* at least one arg */ |
41 | opt = getopt32(argv, "+c"); /* +: stop on first non-opt */ |
42 | argv += optind; |
43 | |
44 | /* setsid() is allowed only when we are not a process group leader. |
45 | * Otherwise our PID serves as PGID of some existing process group |
46 | * 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 | */ |
57 | 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 | */ |
68 | return EXIT_SUCCESS; |
69 | } |
70 | |
71 | /* child */ |
72 | /* now there should be no error: */ |
73 | setsid(); |
74 | } |
75 | |
76 | if (opt) { |
77 | /* -c: set (with stealing) controlling tty */ |
78 | ioctl(0, TIOCSCTTY, 1); |
79 | } |
80 | |
81 | BB_EXECVP_or_die(argv); |
82 | } |
83 |