2 files changed, 10 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index 799d58656e..a878806aa1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Oct 18 14:37:56 2015  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* random.c (fill_random_bytes_urandom): add a comment why using
+	  O_NONBLOCK and O_NOCTTY.
+
 Sun Oct 18 13:30:56 2015  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* random.c (fill_random_bytes_syscall): don't use GRND_NONBLOCK.
diff --git a/random.c b/random.c
index 3fcc4243e6..e73e3dec06 100644
--- a/random.c
+++ b/random.c
@@ -455,6 +455,11 @@ random_init(int argc, VALUE *argv, VALUE obj)
 static int
 fill_random_bytes_urandom(void *seed, size_t size)
 {
+    /*
+      O_NONBLOCK and O_NOCTTY is meaningless if /dev/urandom correctly point
+      to urandom device. But it protect from several strange hazard if
+      /dev/urandom is not urandom device.
+    */
     int fd = rb_cloexec_open("/dev/urandom",
 # ifdef O_NONBLOCK
 			     O_NONBLOCK|