Re: gtk+ applications crash when filechooser opened

[Carl Michal <michal at physics dot ubc dot ca>]

On Fri, 13 Dec 2013, Corinna Vinschen wrote:

> On Dec 13 09:31, Ken Brown wrote:
> > [This is a followup to
> > http://cygwin.com/ml/cygwin/2013-12/msg00255.html; see also
> > http://cygwin.com/ml/cygwin/2013-12/msg00146.html]
> >
> > On 12/13/2013 2:12 AM, Carl Michal wrote:
> > > I recently started trying to port a gtk program to cygwin, and have
> > > found that my program crashes everytime it tries to open a file chooser
> > > widget.
> > >
> > > This doesn't happen with just my own programs, but also with gvim and
> > > emacs-x11. Either will start up ok, but both crash as soon as File->Open
> > > is selected.
> >
> > FWIW, here's one more data point.  I can confirm this behavior of
> > gvim and emacs-X11, but on x86 only.  The File->Open dialog works
> > fine in both gvim and emacs-X11 on x86_64.
>
> A crash at this point would indicate a broken value returned from
> *g_private_get_impl (key).  It should be a valid pthread_key_t
> value but appears not to be one, for some reason.

What's interesting is that the call to open the filechooser hits this 
routine (g_private_get) a few times (through g_slice_alloc). If you 
don't try to step into pthread_getspecific, it crashes on the third time 
it is called. The same key is returned by g_private_get_impl every time.

Trying to follow into pthread_getspecific gets really weird though. The 
debugger can't see the argument at all - says it doesn't exist in the 
current context. It appears that if I step into pthread_getspecific it 
crashes every time.

I'm a little boggled here - there are 40 odd calls to pthread_getspecific 
that occur while my program starts up, and they appear to complete 
successfully, unless I try to follow with the debugger.

This is from an early call to pthread_getspecific, that wouldn't crash if 
I wasn't running in the debugger:

0x6c62fe70 in pthread_getspecific ()
    at /usr/src/debug/cygwin-1.7.27-2/winsup/cygwin/thread.cc:2617
2617    {
gdb) 
list
2612      return 0;
2613    }
2614
2615    extern "C" void *
2616    pthread_getspecific (pthread_key_t key)
2617    {
2618      if (!pthread_key::is_good_object (&key))
2619        return NULL;
2620
2621      return (key)->get ();
(gdb) print key
No symbol "key" in current context.
(gdb) s
/netrel/src/gdb-7.6.50-4/gdb/infrun.c:1942: internal-error: resume: 
Assertion `pc_in_thread_step_range (pc, tp)' failed.
A problem internal to GDB has been detected,

It crashes at line 2617 - before even getting to any of the code in the 
function!

I haven't tried this on the 64 bit install, but will try to.

Carl


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