[PATCH nilfs-utils v2 2/4] cleanerd: call _exit(2) twice for ensuring not being a session leader

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Current daemonize() function of cleanerd call _exit(2) only once during its
process of becoming a daemon process. But in the linux environment, a daemon
should call _exit(2) twice for ensuring not being a session leader. If a
process don't do that, unexpected SIGHUP can be sent to the process (though it
happens rarely). The signal would be confusing event for cleanerd of nilfs. This
patch removes this potential problem.

Signed-off-by: Hitoshi Mitake <mitake.hitoshi@xxxxxxxxxxxxx>
---
 sbin/cleanerd/cleanerd.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sbin/cleanerd/cleanerd.c b/sbin/cleanerd/cleanerd.c
index 0b5bb70..86dfcf7 100644
--- a/sbin/cleanerd/cleanerd.c
+++ b/sbin/cleanerd/cleanerd.c
@@ -708,6 +708,14 @@ static int daemonize(int nochdir, int noclose)
 
 	/* umask(0); */
 
+	/* for ensuring I'm not a session leader */
+	pid = fork();
+	if (pid < 0)
+		return -1;
+	else if (pid != 0)
+		/* parent */
+		_exit(0);
+
 	if (!nochdir && (chdir(ROOTDIR) < 0))
 		return -1;
 
-- 
1.8.1.2

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