Issue paramiko#537 reproduction test and fix

paramiko/buffered_pipe.py

@@ -70,11 +70,15 @@ def set_event(self, event):
         
         :param threading.Event event: the event to set/clear
         """
-        self._event = event
-        if len(self._buffer) > 0:
-            event.set()
-        else:
-            event.clear()
+        self._lock.acquire()
+        try:
+            self._event = event
+            if self._closed or len(self._buffer) > 0:
+                event.set()
+            else:
+                event.clear()
+        finally:
+            self._lock.release()
 
     def feed(self, data):
         """

tests/test_transport.py

@@ -812,3 +812,21 @@ def test_L_handshake_timeout(self):
                           hostkey=public_host_key,
                           username='slowdive',
                           password='pygmalion')
+
+    def test_M_select_after_close(self):
+        """
+        verify that select works when a channel is already closed.
+        """
+        self.setup_test_server()
+        chan = self.tc.open_session()
+        chan.invoke_shell()
+        schan = self.ts.accept(1.0)
+        schan.close()
+
+        # give client a moment to receive close notification
+        time.sleep(0.1)
+
+        r, w, e = select.select([chan], [], [], 0.1)
+        self.assertEqual([chan], r)
+        self.assertEqual([], w)
+        self.assertEqual([], e)