some fixes!

[Isaac Dupree]

On 01/03/2013 02:32 PM, Joachim Breitner wrote:
> Dear Isaac,
>
> Am Sonntag, den 30.12.2012, 18:05 -0500 schrieb Isaac Dupree:
>> Funny story: I found arbtt because I was writing exactly the same idea
>> in Haskell, searched for Haskell bindings to the XScreenSaver extension,
>> and the arbtt repository was the only one that had those bindings.
>> (Off-topic: Those bindings should probably be in the X11 package.)
>>
>> I attached the darcs patches I needed to get arbtt working well enough
>> for me on GHC 7.6.1 and XMonad (on Arch Linux).  Did I do 'darcs send'
>> right?  Do the patches need improvement?
>
> thanks. I am surprised that you need patches to get it working with
> xmonad, as that is basically the only well-tested setup, namely mine.
>
> It does require the use of XMonad.Hooks.EwmhDesktops, which makes it set
> _NET_CLIENT_LIST and does not require special code on arbtt’s side. Is
> there a reason why you cannot use that?

Lack of knowing that it exists... I will go use that now!  Maybe it 
could be in arbtt documentation or the error message (or did I just miss 
it?).

> Thanks for the 7.6 compat patch, applied.
>
> Am Dienstag, den 01.01.2013, 16:49 -0500 schrieb Isaac Dupree:
>> arbtt-capture segfaults occasionally for me[1].  Valgrind didn't tell me
>> why (I think valgrind is better for C and C++ memory errors than Haskell).
>>
>> So now I run arbtt-capture with this script to restart it:
>>
>>     while true; do ./arbtt-capture; echo; echo "Whoops dead" >&2; date;
>> sleep 30; echo "; restarting" >&2; done
>>
>> (which works fine, though it'd be nice to know why arbtt-capture
>> segfaults :-) )
>
> I don’t have that here, so no idea what is happening. Can you run it in
> gdb and obtain a stacktrace, in case the crash happens in C world?

It crashes like below[1][2] (even without GDB) so perhaps it's some 
prior memory corruption.

[1]
*** glibc detected *** ./arbtt-capture: munmap_chunk(): invalid pointer: 
0x00007f5ae4b3dfc9 ***
======= Backtrace: =========
/usr/lib/libc.so.6(+0x798a6)[0x7f5ae59568a6]
/usr/lib/libX11.so.6(XFree+0x9)[0x7f5ae6650e09]
./arbtt-capture[0x4779ea]

[2]
*** glibc detected *** ./arbtt-capture: free(): invalid size: 
0x00000000005278b0 ***
======= Backtrace: =========
/usr/lib/libc.so.6(+0x798a6)[0x7ff3d02df8a6]
/usr/lib/libX11.so.6(XFree+0x9)[0x7ff3d0fd9e09]
./arbtt-capture[0x4779ea]