hust testsuite: fix a false positive

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

diff --git a/miscutils/setsid.c b/miscutils/setsid.c
index fd3283e30def9d2ae0a98396fab42f62bf7a1505..9bddc2fcf0ba6d69bad108567bcd1a0ce4fbddb8 100644 (file)
--- a/miscutils/setsid.c
+++ b/miscutils/setsid.c
@@ -14,17 +14,37 @@
  * - 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. */
+        * 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) {
@@ -36,7 +56,7 @@ int setsid_main(int argc UNUSED_PARAM, char **argv)
                         * However, the code is larger and upstream
                         * does not do such trick.
                         */
-                       exit(EXIT_SUCCESS);
+                       return EXIT_SUCCESS;
                }
 
                /* child */
@@ -44,6 +64,10 @@ int setsid_main(int argc UNUSED_PARAM, char **argv)
                setsid();
        }
 
-       BB_EXECVP(argv[1], argv + 1);
-       bb_simple_perror_msg_and_die(argv[1]);
+       if (opt) {
+               /* -c: set (with stealing) controlling tty */
+               ioctl(0, TIOCSCTTY, 1);
+       }
+
+       BB_EXECVP_or_die(argv);
 }