[git commit master] setsid: check for setsid error directly

[Denys Vlasenko]

commit: http://git.busybox.net/busybox/commit/?id=a29b055bf1c21fb65bfeb5fdd982dfcd15f2b360
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master

function                                             old     new   delta
setsid_main                                           74      66      -8

Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 miscutils/setsid.c |   21 +++++++++++++++++----
 1 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/miscutils/setsid.c b/miscutils/setsid.c
index d7de1f1..fd3283e 100644
--- a/miscutils/setsid.c
+++ b/miscutils/setsid.c
@@ -25,11 +25,24 @@ int setsid_main(int argc UNUSED_PARAM, char **argv)
 	/* 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())
-		if (fork_or_rexec(argv))
-			exit(EXIT_SUCCESS); /* parent */
+	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.
+			 */
+			exit(EXIT_SUCCESS);
+		}
 
-	setsid();  /* no error possible */
+		/* child */
+		/* now there should be no error: */
+		setsid();
+	}
 
 	BB_EXECVP(argv[1], argv + 1);
 	bb_simple_perror_msg_and_die(argv[1]);
-- 
1.6.3.3