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