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authorDenys Vlasenko <vda.linux@googlemail.com>2013-08-07 16:49:51 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2013-08-07 16:49:51 (GMT)
commita5e6c6cd3b458e20643a9cd4202091720901a4d0 (patch)
treecadae7e89b93ef69141e577e69dda539e7571be4
parent543efd7b4b4265ae507b4e3b048bf23a51a726fc (diff)
downloadbusybox-a5e6c6cd3b458e20643a9cd4202091720901a4d0.tar.gz
busybox-a5e6c6cd3b458e20643a9cd4202091720901a4d0.tar.bz2
setsid: code shrink, expanded comments
function old new delta setsid_main 56 53 -3 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--miscutils/setsid.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/miscutils/setsid.c b/miscutils/setsid.c
index ad2c8a4..637081b 100644
--- a/miscutils/setsid.c
+++ b/miscutils/setsid.c
@@ -31,7 +31,17 @@ 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. */
+ * 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) {
@@ -43,7 +53,7 @@ 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 */