/* 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); }