Merge pull request #309 from hurtonm/fix_issue_335

Fix issue #335

src/signaler.cpp

@@ -238,7 +238,13 @@ int zmq::signaler_t::make_fdpair (fd_t *r_, fd_t *w_)
     //  two instances of the library don't accidentally create signaler
     //  crossing the process boundary.
     //  We'll use named event object to implement the critical section.
-    HANDLE sync = CreateEvent (NULL, FALSE, TRUE, TEXT("zmq-signaler-port-sync"));
+    //  Note that if the event object already exists, the CreateEvent requests
+    //  EVENT_ALL_ACCESS access right. If this fails, we try to open
+    //  the event object asking for SYNCHRONIZE access only.
+    HANDLE sync = CreateEvent (NULL, FALSE, TRUE, TEXT ("zmq-signaler-port-sync"));
+    if (sync == NULL && GetLastError () == ERROR_ACCESS_DENIED)
+      sync = OpenEvent (SYNCHRONIZE, FALSE, TEXT ("zmq-signaler-port-sync"));
+
     win_assert (sync != NULL);
 
     //  Enter the critical section.