bug#25875: 26.0.50; Hang logging out of MS-Windows

[Ken Brown <kbrown@cornell.edu>]

On 2/26/2017 2:25 PM, Eli Zaretskii wrote:
>> Cc: rcopley@gmail.com, 25875@debbugs.gnu.org
>> From: Ken Brown <kbrown@cornell.edu>
>> Date: Sun, 26 Feb 2017 13:58:23 -0500
>>
>>> I think the problem in this particular scenario is not that the input
>>> thread sleeps too long, it's that whenever it finishes sleeping and
>>> returns, Emacs will be killed, so the WM_ENDSESSION message that was
>>> posted to the main thread will never have a chance to be processed,
>>> and thus orderly shutdown will never happen.
>>>
>>> That is why I thought about using SendMessageTimeout in the main
>>> thread: what we really want is to cause the main thread to wake up and
>>> process the WM_ENDSESSION message.  Right?
>>
>> Yes, that would obviously be better.
>
> OK.  Can you propose a patch that Richard could try?

Here's a quick and dirty attempt.  If I haven't made a mistake, it 
replaces every relevant call to SendMessage by a call to 
SendMessageTimeout with a 100ms timeout.

--- a/src/w32term.c
+++ b/src/w32term.c
@@ -537,6 +537,15 @@ x_update_begin (struct frame *f)
  }


+#undef SendMessage
+#define SendMessage DebugSendMessage
+
+static LRESULT WINAPI
+DebugSendMessage (HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
+{
+  return SendMessageTimeoutA (hWnd, Msg, wParam, lParam, 0, 100, NULL);
+}
+
  /* Start update of window W.  */

  static void

Ken