Re: [XForms] Problem with fdesign (fdesigns menu bar) (fwd)

[Clive Stubbings]

Try

-       XStoreName(flx->display, m->win, m->title);
+       XStoreName(flx->display, m->win, m->title ? m->title : "");

Cheers
Clive

On Thu, 12 May 2022, Michal Szymanski wrote:

> I have built the current git version
> (https://git.savannah.gnu.org/git/xforms.git) on Ubuntu 20.04 and
> Rocky Linux 8.5 and got the same problem: fdesign segfaults when
> 'File' is clicked on.
>
> Following Clive's hint I have found just 4 places XStoreName is used:
>
> lib/canvas.c:            XStoreName( flx->display, sp->window, ob->label );
> lib/canvas.c:            XStoreName( flx->display, sp->window, name );
> lib/popup.c:        XStoreName( flx->display, popup->win, popup->title );
> lib/xpopup.c:        XStoreName( flx->display, m->win, m->title );
>
> but I do not have any idea how to fix the problem. I have even
> localized the segfault to be originating in 'xpopup.c', with m->title
> being 0x0, so I made it point to an empty static string (""). The
> program did not segfault on "File" but aborted on "SaveAs" from File
> popup, saying
> munmap_chunk(): invalid pointer
> Abort (core dumped)
>
> so I surrendered.
>
> Any more hints? Without working fdesign the whole library is pretty unusable :(
>
> regards, Michal
>
> On Wed, Jun 30, 2021 at 02:27:35AM +0100, Clive Stubbings wrote:
> > Hi,
> >
> > There has been a regression in the xorg libX11
> >
> > It is likely this is your issue - it was spotted in one of my xforms programs a 
> > few weeks ago by one of my users.
> >
> > XStoreName used to tolerate a NULL pointer (it checked before using it). New 
> > code has been added ahead of that check.
> >
> > If your system has recently updated its libraries, thats likely the cause.
> >
> > I believe it has now been fixed upstream thanks to the person who spotted the 
> > problem feeding the cause back to the developers and a new version should come 
> > through in due course.
> >
> > If you need a quicker fix, hack the library to make sure it doesn't pass a NULL 
> > pointer to XStoreName.
> >
> > Cheers
> > Clive
> >
> >
> >
> > On Sun, 27 Jun 2021, ternaryd wrote:
> >
> > > On Sat, 26 Jun 2021 15:47:12 -0700
> > > Coby Hochstein <cjh39@cox.net> wrote:
> > >
> > > > Hello,
> > > >
> > > > when I load fdesign and click on the "File"
> > > > menu bar fdesign segmentation faults.
> > > > I'm running xforms-1.2.4
> > > >
> > > > (gdb) run
> > > > Starting program: /usr/local/bin/fdesign
> > > > [Thread debugging using libthread_db enabled]
> > > > Using host libthread_db library
> > > > "/lib/arm-linux-gnueabihf/libthread_db.so.1".
> > > >
> > > > Program received signal SIGSEGV, Segmentation
> > > > fault.
> > > > strlen () at ../sysdeps/arm/armv6/strlen.S:26
> > > > 26 ../sysdeps/arm/armv6/strlen.S: No such
> > > > file or directory.
> > > > (gdb)
> > >
> > >
> > > > Any idea ?
> > >
> > > fdesign is calculating the string length of a
> > > string pointing to NULL.
> > >
> > > Use a version of fdesign compiled with debugging
> > > enabled, run it again until crash, and check the
> > > coredump in gdb. Use the "up" command until you
> > > reach a stack level belonging to fdesign (or
> > > xforms). You should see which pointer is NULL.
> > > Then you can try to figure out, why it is NULL
> > > and how to fix it.
> > >
> > >   $ ulimit -c unlimited
> > >   $ ./fdesign ...
> > >   $ gdb ./fdesign coredump
> > >   (gdb> up
> > >   ...
> > >
> > > you can query the value of any variable at the
> > > time of the crash with
> > >
> > >   (gdb) p varname
> > >
> > > HTH
> > >
> > > --
> > > Cris
>
> --
>  Michal Szymanski (msz at astrouw dot edu dot pl)
>  Warsaw University Observatory, Warszawa, POLAND