source: MondoRescue/branches/3.2/mindi-busybox/miscutils/setsid.c@ 3232

/* 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
 */

//usage:#define setsid_trivial_usage
//usage:       "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 (Ctrl-C etc).\n"
//usage:       "See setsid(2) for details."

#include "libbb.h"

int setsid_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int setsid_main(int argc UNUSED_PARAM, char **argv)
{
    if (!argv[1])
        bb_show_usage();

    /* 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. */
    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.
             */
            exit(EXIT_SUCCESS);
        }

        /* child */
        /* now there should be no error: */
        setsid();
    }

    argv++;
    BB_EXECVP_or_die(argv);
}