[Therion] loch segmentation fault at launch

[Martin Budaj]

Thanks Olly, patch applied in Git repo.
M.

On Tue, Jan 14, 2025 at 2:39 AM Olly Betts <olly at survex.com> wrote:
>
> [Including the list in my reply as this seems of broader interest]
>
> On Mon, Jan 13, 2025 at 04:52:46PM -0600, Bill Gee wrote:
> > Olly, you're a wizard for remembering that bit of arcana.  The command line
> > you suggested works.  No more seg faults in loch!
>
> Great.
>
> > I do not have any packages called "wxWidgets" installed.  On Fedora they are
> > called wxGTK.  Here is the list of packages I have:
> >
> > bgee at main2:~$ rpm -qa | grep -i wxGTK
> > wxGTK-i18n-3.2.6-1.fc41.noarch
> > wxGTK-3.2.6-1.fc41.x86_64
> > wxGTK-gl-3.2.6-1.fc41.x86_64
> > wxGTK-webview-3.2.6-1.fc41.x86_64
> > wxGTK-media-3.2.6-1.fc41.x86_64
> > wxGTK-devel-3.2.6-1.fc41.x86_64
>
> Its upstream project name is wxWidgets - wxGTK is the flavour using GTK,
> which Fedora have chosen to use as their package name.
>
> > I also do not have any packages like "libglew".  It might be part of the VTK
> > package.  I see a file named vtk-glew.h.
>
> It's not part of VTK - that header seems to be some VTK layer for
> supporting building with different versions of glew.
>
> I don't think wxWidgets or therion uses glew so you may well not have it
> installed, but some other apps which use wxWidgets also use glew - I
> think it's necessary that wxWidgets and glew agree on whether to use EGL
> or not for those apps.
>
> > I will modify the launcher for loch to set the environment variable.
>
> We have a workaround in Survex's aven for this - I'd suggest something
> similar in loch would be helpful as it would avoid these crashes
> completely.  I'm not easily able to test this patch actually works as I
> don't have Fedora but this or something like it should do the job (I
> have checked it compiles on a platform where the conditionals both
> evaluate true):
>
> diff --git a/loch/lxGUI.cxx b/loch/lxGUI.cxx
> index fc00b31e..41a4583c 100644
> --- a/loch/lxGUI.cxx
> +++ b/loch/lxGUI.cxx
> @@ -73,7 +73,29 @@
>  #endif
>
>
> +#ifdef __WXGTK3__
> +# if !(wxUSE_GLCANVAS_EGL-0)
> +#  include <stdlib.h>
> +
> +// The GLX-based wxGLCanvas doesn't work under Wayland, and the code
> +// segfaults: https://github.com/wxWidgets/wxWidgets/issues/17702
> +//
> +// Therefore we force X11 unless we're using the EGL-based wxGLCanvas
> +// (which was added in wxWidgets 3.1.5 and hasn't been backported to
> +// 3.0.x).
> +//
> +// Setting GDK_BACKEND=x11 is the recommended workaround, and it seems to
> +// work to set it here.  GTK2 doesn't support Wayland, so doesn't need
> +// this.
> +struct ForceX11 {
> +    ForceX11() {
> +       setenv("GDK_BACKEND", "x11", 1);
> +    }
> +};
> +static ForceX11 forcex11;
>
> +# endif
> +#endif
>
>  ////////////////////////////////////////////////////////////////////////
>  // Main frame
>
>
> Cheers,
>     Olly
> _______________________________________________
> Therion mailing list
> Therion at speleo.sk
> https://mailman.speleo.sk/listinfo/therion