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/* vi: set sw=4 ts=4: */
/*
* setsid.c -- execute a command in a new session
* Rick Sladkey <jrs@world.std.com>
* In the public domain.
*
* 1999-02-22 Arkadiusz Mickiewicz <misiek@pld.ORG.PL>
* - added Native Language Support
*
* 2001-01-18 John Fremlin <vii@penguinpowered.com>
* - fork in case we are process group leader
*
* 2004-11-12 Paul Fox
* - busyboxed
*/
//config:config SETSID
//config: bool "setsid (3.6 kb)"
//config: default y
//config: help
//config: setsid runs a program in a new session
//applet:IF_SETSID(APPLET(setsid, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_SETSID) += setsid.o
//usage:#define setsid_trivial_usage
//usage: "[-c] PROG ARGS"
//usage:#define setsid_full_usage "\n\n"
//usage: "Run PROG in a new session. PROG will have no controlling terminal\n"
//usage: "and will not be affected by keyboard signals (^C etc).\n"
//usage: "\n -c Set controlling terminal to stdin"
#include "libbb.h"
int setsid_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int setsid_main(int argc UNUSED_PARAM, char **argv)
{
unsigned opt;
/* +: stop on first non-opt */
opt = getopt32(argv, "^+" "c" "\0" "-1"/* at least one arg */);
argv += optind;
/* setsid() is allowed only when we are not a process group leader.
* Otherwise our PID serves as PGID of some existing process group
* and cannot be used as PGID of a new process group.
*
* Example: setsid() below fails when run alone in interactive shell:
* $ setsid PROG
* because shell's child (setsid) is put in a new process group.
* But doesn't fail if shell is not interactive
* (and therefore doesn't create process groups for pipes),
* or if setsid is not the first process in the process group:
* $ true | setsid PROG
* or if setsid is executed in backquotes (`setsid PROG`)...
*/
if (setsid() < 0) {
pid_t pid = fork_or_rexec(argv);
if (pid != 0) {
/* parent */
/* TODO:
* we can waitpid(pid, &status, 0) and then even
* emulate exitcode, making the behavior consistent
* in both forked and non forked cases.
* However, the code is larger and upstream
* does not do such trick.
*/
return EXIT_SUCCESS;
}
/* child */
/* now there should be no error: */
setsid();
}
if (opt) {
/* -c: set (with stealing) controlling tty */
ioctl(0, TIOCSCTTY, 1);
}
BB_EXECVP_or_die(argv);
}
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