From f14356733e83e5af35ec5c9f2346bf9607fc3a16 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Tue, 2 Feb 2016 22:14:16 +0000
Subject: support idempotent POSIX_MQ#close

IO#close under Ruby 2.3 is idempotent, we shall follow suit
with POSIX_MQ#close
---
 ext/posix_mq/extconf.rb | 11 +++++++++++
 ext/posix_mq/posix_mq.c | 10 +++++++++-
 test/test_posix_mq.rb   | 16 +++++++++++++++-
 3 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/ext/posix_mq/extconf.rb b/ext/posix_mq/extconf.rb
index eb799b2..d433d1d 100644
--- a/ext/posix_mq/extconf.rb
+++ b/ext/posix_mq/extconf.rb
@@ -14,4 +14,15 @@ have_library("pthread")
 have_func("__mq_oshandle")
 have_func("mq_timedsend")
 have_func("mq_timedreceive")
+
+r, w = IO.pipe
+r.close
+w.close
+begin
+  r.close
+  $CPPFLAGS += ' -DIDEMPOTENT_IO_CLOSE=1'
+rescue IOError
+  $CPPFLAGS += ' -DIDEMPOTENT_IO_CLOSE=0'
+end
+
 create_makefile("posix_mq_ext")
diff --git a/ext/posix_mq/posix_mq.c b/ext/posix_mq/posix_mq.c
index 5e1b3b8..0567676 100644
--- a/ext/posix_mq/posix_mq.c
+++ b/ext/posix_mq/posix_mq.c
@@ -824,7 +824,15 @@ static VALUE setattr(VALUE self, VALUE astruct)
  */
 static VALUE _close(VALUE self)
 {
-	struct posix_mq *mq = get(self, 1);
+	struct posix_mq *mq;
+
+	if (IDEMPOTENT_IO_CLOSE) { /* defined in extconf.rb */
+		mq = get(self, 0);
+		if (!mq || (mq->des == MQD_INVALID))
+			return Qnil;
+	} else {
+		mq = get(self, 1);
+	}
 
 	if (! MQ_IO_CLOSE(mq)) {
 		if (mq_close(mq->des) < 0)
diff --git a/test/test_posix_mq.rb b/test/test_posix_mq.rb
index d726d36..e831012 100644
--- a/test/test_posix_mq.rb
+++ b/test/test_posix_mq.rb
@@ -152,7 +152,21 @@ class Test_POSIX_MQ < Test::Unit::TestCase
       assert_equal true, mq.send("HI", 0)
       assert_equal 1, mq.attr.curmsgs
       assert_nil mq.close
-      assert_raises(IOError) { mq.close }
+
+      r, w = IO.pipe
+      w.close
+      r.close
+      idempotent_close = begin
+        r.close
+        true
+      rescue IOError
+        false
+      end
+      if idempotent_close
+        2.times { assert_nil mq.close }
+      else
+        assert_raises(IOError) { mq.close }
+      end
     end
     assert @mq.closed?
     @mq = nil
-- 
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