hust testsuite: fix a false positive

[oweals/busybox.git] / miscutils / setsid.c

diff --git a/miscutils/setsid.c b/miscutils/setsid.c
index 127adf6f2822cc1bedfd6d4f99e1b51e3742389c..9bddc2fcf0ba6d69bad108567bcd1a0ce4fbddb8 100644 (file)
--- a/miscutils/setsid.c
+++ b/miscutils/setsid.c
@@ -14,22 +14,60 @@
  * - 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 UNUSED_PARAM, char **argv)
 {
-       if (!argv[1])
-               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. */
-       if (getpgrp() == getpid())
-               forkexit_or_rexec(argv);
+        * 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();
+       }
 
-       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);
 }