Re: [RFC] control-c handling on Windows...

[Joel Brobecker <brobecker@adacore.com>]

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Hi Chris,

> Checking this in is ok with me but it would be nice to consider a better
> solution eventually.  Could you put a note to that effect in the patch

Attached is the patch that I ended up checking in. Let me know if you'd
like me to make some adjustments to the comment...

2008-05-20  Joel Brobecker  <brobecker@adacore.com>

        * win32-nat.c (win32_wait): Block the control-c event while
        waiting for a debug event.

-- 
Joel

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Index: win32-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/win32-nat.c,v
retrieving revision 1.151
diff -u -p -r1.151 win32-nat.c
--- win32-nat.c	11 Mar 2008 05:21:38 -0000	1.151
+++ win32-nat.c	20 May 2008 18:33:29 -0000
@@ -1458,7 +1458,25 @@ win32_wait (ptid_t ptid, struct target_w
 
   while (1)
     {
-      int retval = get_win32_debug_event (pid, ourstatus);
+      int retval;
+      
+      /* Ignore CTRL+C signals while waiting for a debug event.
+         FIXME: brobecker/2008-05-20: When the user presses CTRL+C while
+         the inferior is running, both the inferior and GDB receive the
+         associated signal.  If the inferior receives the signal first
+         and the delay until GDB receives that signal is sufficiently long,
+         GDB can sometimes receive the SIGINT after we have unblocked
+         the CTRL+C handler.  This would lead to the debugger to stop
+         prematurely while handling the new-thread event that comes
+         with the handling of the SIGINT inside the inferior, and then
+         stop again immediately when the user tries to resume the execution
+         in the inferior.  This is a classic race, and it would be nice
+         to find a better solution to that problem.  But in the meantime,
+         the current approach already greatly mitigate this issue.  */
+      SetConsoleCtrlHandler (NULL, TRUE);
+      retval = get_win32_debug_event (pid, ourstatus);
+      SetConsoleCtrlHandler (NULL, FALSE);
+
       if (retval)
 	return pid_to_ptid (retval);
       else