Re: catch logout/SIGHUP

[Ben Johnson <ben blarg net>]

On Thu, Jul 21, 2005 at 03:39:46AM +0200, Jochen Baier wrote:
> hi,
> 
> i wonder what is the right procedure to do some cleanup if the user 
> logout from session
> and the program is still alive. ("Save file before exit" etc)
> 
> I thought "system (SIGHUP,...)" is the right way, but i didnt find this 
> function in code from gedit, anjuta etc.. so what is  the right way to 
> do this ?

as far as I know glib and gdk/gtk haven't added any support for signal
handling, so I imagine using sigaction() and associated POSIX functions
are what you'd want to use.  (what is this system(SIGHUP,...) of which
you speak?  never heard of it.)

the only thing I'm aware of that needs to be said about signal handling
in relation to gtk is about dealing with asynchronous nature of signals.
gtk assumes it knows everything about what threads are running.  if you
start executing gtk code during a signal handler, you run the (very
probable) risk of making gtk stomp on itself when your handler runs on
top of what gtk thinks is a thread-autonomous operation.

I'm not sure exactly what mechanism to use...  but the best way to
handle signals is to make the actual signal handler do something very
simple and non-gtk-interactive/invasive like setting some kind of simple
flag -- THEN engineer some way for the gtk main loop to respond to that
flag being set.  make sense?

- Ben