Bug#430819: fluxbox aborts on upgrade to xserver 1.3

[Brice Goglin <Brice.Goglin@ens-lyon.org>]

J.J.Green wrote:
> Hi Brice
>
>   
>> Any news about this? Did you have a chance to look at where the segfault
>> occurs so that we know whether the bug is in the server or in fluxbox?
>>     
>
> I made a fluxbox-dbg and installed xserver-xorg-code-dbg,
> then installed the problematic xserver, ran
>
>   startx /usr/bin/xterm
>
> and got an x-shell, then ran
>
>   gdb /usr/bin/fluxbox
>   gdb> run
>   
> and the shell hangs, so no bt possible. Looking at the 
> process tree in a console window (I use whowatch for this)
> I see that fluxbox (spawned from gdb) has a "T" next to it 
> (I'm not sure what this means, perhaps you do! The same program 
> shows a "Z" in the same position for zombie processes)
>   

You can't run gdb from a terminal in X when debugging something related
to X. Since the X crash will be caught by gdb, gdb will interrupt X, and
thus make it impossible for you to enter anything in gdb (all keyboard
events are caught by X before going to gdb, but X is interrupted). You
should start fluxbox by logging from another machine with ssh, exporting
DISPLAY=:0 in your environment, and doing gdb stuff then.

> Reverting to the old xserver and all of the above (the gdb
> etc) worked as expected.
>
> So not much help I think. Any more ideas?
>   

One possible cause for the problem could be that Xserver 1.3 is known to
not report Xinerama capabilities correctly, which can confuse clients.
If this wrong Xserver behavior causes fluxbox to crash, that would
explain the problem. To test it quickly, open src/Screen.cc in the
fluxbox source, go to BScreen::initXinerama() and change
  if (!XineramaIsActive(display)) {
into
  if (1)

This Xserver bug is already fixed in xserver-xorg-core 1.4, which has
been uploaded to unstable yesterday. Once it will be built for your
architecture, you should try it. But you would have to upgrade multiple
packages because of the ABI bump, so upgrading/downgrading multiple
times for testing would be a pain. The above fluxbox modification is
much easier to test for now.

Brice