websocket: restore signals after processing

WebSocketServer is a library module, as such it should try to restore state
after processing, to allow caller to resume normal operation.

Signed-off-by: Alon Bar-Lev <alon.barlev@gmail.com>

utils/websocket.py

@@ -842,6 +842,11 @@ Sec-WebSocket-Accept: %s\r
         self.started()  # Some things need to happen after daemonizing
 
         # Allow override of signals
+        original_signals = {
+            signal.SIGINT: signal.getsignal(signal.SIGINT),
+            signal.SIGTERM: signal.getsignal(signal.SIGTERM),
+            signal.SIGCHLD: signal.getsignal(signal.SIGCHLD),
+        }
         signal.signal(signal.SIGINT, self.do_SIGINT)
         signal.signal(signal.SIGTERM, self.do_SIGTERM)
         if not multiprocessing:
@@ -849,6 +854,7 @@ Sec-WebSocket-Accept: %s\r
             signal.signal(signal.SIGCHLD, self.fallback_SIGCHLD)
 
         last_active_time = self.launch_time
+        try:
             while True:
                 try:
                     try:
@@ -944,12 +950,16 @@ Sec-WebSocket-Accept: %s\r
                 finally:
                     if startsock:
                         startsock.close()
-
+        finally:
             # Close listen port
             self.vmsg("Closing socket listening at %s:%s"
                     % (self.listen_host, self.listen_port))
             lsock.close()
 
+            # Restore signals
+            for sig, func in original_signals.items():
+                signal.signal(sig, func)
+
 
 # HTTP handler with WebSocket upgrade support
 class WSRequestHandler(SimpleHTTPRequestHandler):