[GRASS-dev] Re: [GRASS GIS] #869: Compile libs with -fexception

[Soeren Gebbert]

I use in vtk.grass-bridge (C++ -VTK GRASS wrapper) a different approach.
http://code.google.com/p/vtk-grass-bridge/

Replacing the G_fatal_error() function and using the setjmp/longjmp
construct allows you to catch all errors from grass, inclusively stack
restoration. Glynn made this suggestion. :)

This function replace G_fatal_error(), to set with
G_set_error_routine(vgb_error_handler);:

int vgb_error_handler(const char *msg, int fatal)
{
    if (fatal == 0)
    {
        fprintf(stderr, "%s\n", msg);
        return 1;
    }
    else
    {
        fprintf(stderr, "\n############## Exceptiont called ###########\n");
        vgb_error_message = msg;
        longjmp(vgb_stack_buffer, 1);
    }
    return 1;
}


This is an example how to handle fatal errors (old example, still
check for return value):
    if (!setjmp(vgb_stack_buffer))
    {
        if (Rast_get_row(this->Map, this->RasterBuff, idx, this->MapType) < 0)
        {
            error = 1;
        }
    }
    else
    {
        this->InsertNextError(vgb_error_message);
        return NULL;
    }

Code examples from:
http://code.google.com/p/vtk-grass-bridge/source/browse/trunk/Common/vtkGRASSDefines.h
http://code.google.com/p/vtk-grass-bridge/source/browse/trunk/Common/vtkGRASSInit.cxx
http://code.google.com/p/vtk-grass-bridge/source/browse/trunk/Raster/vtkGRASSRasterMapBase.cxx

Soeren


2010/1/14 GRASS GIS <trac at osgeo.org>:
> #869: Compile libs with -fexception
> --------------------------+-------------------------------------------------
>  Reporter:  rblazek      |       Owner:  grass-dev at lists.osgeo.org
>      Type:  defect       |      Status:  closed
>  Priority:  normal       |   Milestone:  6.5.0
>  Component:  Compiling    |     Version:  unspecified
> Resolution:  worksforme   |    Keywords:
>  Platform:  Unspecified  |         Cpu:  All
> --------------------------+-------------------------------------------------
> Comment (by rblazek):
>
>  Replying to [comment:8 hamish]:
>  > fwiw, wrt. -fexceptions, Francesco commented on the DebianGIS list:
>  >
>  {{{
>  This would be required for any C library linked by Qgis. This is out of
>  discussion.
>  Qgis has to manage correctly C libraries by providing wrappers to raise
>  execeptions
>  when C calls fail, else people will start asking that libc too supports
>  exceptions, soon or later...
>  }}}
>
>  Probably he does not know, that GRASS libraries can call exit(). No
>  wrapper can help in that situation AFAIK.
>
> --
> Ticket URL: <https://trac.osgeo.org/grass/ticket/869#comment:9>
> GRASS GIS <http://grass.osgeo.org>
>
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