Re: System shutdown messages

[Ken Brown <kbrown at cornell dot edu>]

On 5/9/2016 1:20 PM, Jon Turney wrote:
> On 09/05/2016 14:35, Ken Brown wrote:
> > A Cygwin emacs user has asked
> > (http://debbugs.gnu.org/cgi/bugreport.cgi?bug=23483) whether emacs can
> > auto-save files when he shuts down Windows from the Start Menu.  Is
> > there a way for a Cygwin process to listen for Windows system shutdown
> > messages?
>
> This seems entirely possible using the Win32 API.
>
> For emacs-w32, it's probably straightforward to handle WM_ENDSESSION in
> the message loop similarly to WM_CLOSE
>
> (Note that the process will be terminated if you return from processing
> a WM_ENDSESSION message)
>
> For emacs-nox and emacs-x11 it's more complex, as you'd have to create
> your own hidden window to receive the WM_ENDSESSION, and either select()
> on a /dev/windows fd or block in GetMessage() on a separate thread.
>
> (see [1] for an example of the latter approach as used in the X server)
>
> But I'm not sure that's the best approach, or if wouldn't be more
> appropriate to arrange for SIGTERM to be sent to emacs (or whatever) by
> mintty or the X server when an WM_ENDSESSION is received...

Thanks, Jon.  Yes, the latter approach seems much better.  Of course, SHTDI.

Ken


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