* Rick Sladkey <jrs@world.std.com>
* In the public domain.
*
- * 1999-02-22 Arkadiusz MiΒΆkiewicz <misiek@pld.ORG.PL>
+ * 1999-02-22 Arkadiusz Mickiewicz <misiek@pld.ORG.PL>
* - added Native Language Support
*
* 2001-01-18 John Fremlin <vii@penguinpowered.com>
* - busyboxed
*/
+//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, char **argv)
+int setsid_main(int argc UNUSED_PARAM, char **argv)
{
- if (argc < 2)
- bb_show_usage();
+ unsigned opt;
+
+ opt_complementary = "-1"; /* at least one arg */
+ opt = getopt32(argv, "+c"); /* +: stop on first non-opt */
+ 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;
+ }
- /* Comment why is this necessary? */
- if (getpgrp() == getpid())
- forkexit_or_rexec(argv);
+ /* child */
+ /* now there should be no error: */
+ setsid();
+ }
- setsid(); /* no error possible */
+ if (opt) {
+ /* -c: set (with stealing) controlling tty */
+ ioctl(0, TIOCSCTTY, 1);
+ }
- BB_EXECVP(argv[1], argv + 1);
- bb_simple_perror_msg_and_die(argv[1]);
+ BB_EXECVP_or_die(argv);
}