ext/socket/init.c: use SOCK_NONBLOCK if available

This saves a system call by allowing us to use SOCK_NONBLOCK in
Linux when accept4 is available.

Note: I do not agree accept_nonblock should always make accepted
sockets non-blocking, and will propose a future API to allow
controlling whether accepted sockets are non-blocking or not
regardless of how they were created.

* ext/socket/init.c (cloexec_accept): support nonblock flag and
  use SOCK_NONBLOCK if possible
* ext/socket/init.c (rsock_s_accept_nonblock): update cloexec_accept call
* ext/socket/init.c (accept_blocking): ditto for blocking
* test/socket/test_nonblock.rb: check nonblock? on accepted socket
  [Feature #11138]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50518 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 4 insertions, 0 deletions

diff --git a/test/socket/test_nonblock.rb b/test/socket/test_nonblock.rb
index 98de00eed9..526825269e 100644
--- a/test/socket/test_nonblock.rb
+++ b/test/socket/test_nonblock.rb
@@ -1,5 +1,6 @@
 begin
   require "socket"
+  require "io/nonblock"
 rescue LoadError
 end
 
@@ -24,6 +25,9 @@ class TestSocketNonblock < Test::Unit::TestCase
       s, sockaddr = serv.accept_nonblock
     end
     assert_equal(Socket.unpack_sockaddr_in(c.getsockname), Socket.unpack_sockaddr_in(sockaddr))
+    if s.respond_to?(:nonblock?)
+      assert s.nonblock?, 'accepted socket is non-blocking'
+    end
   ensure
     serv.close if serv
     c.close if c