avoid unlinking actively listening sockets

While we've always unlinked dead sockets from nuked/leftover
processes, blindly unlinking them can cause unnecessary failures
when an active process is already listening on them.  We now
make a simple connect(2) check to ensure the socket is not in
use before unlinking it.

Thanks to Jordan Ritter for the detailed bug report leading to
this fix.

ref: http://mid.gmane.org/8D95A44B-A098-43BE-B532-7D74BD957F31@darkridge.com
(cherry picked from commit 1a2363b17b1d06be6b35d347ebcaed6a0c940200)

1 files changed, 8 insertions, 1 deletions

diff --git a/test/unit/test_socket_helper.rb b/test/unit/test_socket_helper.rb
index bbce359..c6d0d42 100644
--- a/test/unit/test_socket_helper.rb
+++ b/test/unit/test_socket_helper.rb
@@ -101,7 +101,14 @@ class TestSocketHelper < Test::Unit::TestCase
 
   def test_bind_listen_unix_rebind
     test_bind_listen_unix
-    new_listener = bind_listen(@unix_listener_path)
+    new_listener = nil
+    assert_raises(Errno::EADDRINUSE) do
+      new_listener = bind_listen(@unix_listener_path)
+    end
+    assert_nothing_raised do
+      File.unlink(@unix_listener_path)
+      new_listener = bind_listen(@unix_listener_path)
+    end
     assert UNIXServer === new_listener
     assert new_listener.fileno != @unix_listener.fileno
     assert_equal sock_name(new_listener), sock_name(@unix_listener)