Geometry Boost List: Re: [geometry] access violation in update_discarded(...)

Subject: Re: [geometry] access violation in update_discarded(...)
From: Volker Schöch (vschoech_at_[hidden])
Date: 2014-10-27 13:39:56

Hi,

Unfortunately I have not hear from you in this regard. It seems that I still cannot reliably reproduce the issue, but when it occurs, it occurs in the following scenario. Apparently, something is broken in your memory management:

{      // RT#8837
       _intPolygon polygonA;
       boost::geometry::read_wkt("MULTIPOLYGON(((488 2035,527 2035,527 2093,488 2093)))", polygonA); // does not throw

       _intRect rectB;
       boost::geometry::read_wkt("BOX(417 2064,597 2064)", rectB); // does not throw

       _intPolygon polygonC;
       boost::geometry::difference(polygonA, rectB, polygonC); // ACCESS VIOLATION
}

Maybe you could make an effort and step through this simple example once to see if everything works as expected?

I understand that the box and/or the polygon may not conform to all requirements (not spike-free etc.) but in any case, IMO the geometry library should not crash with a memory fault.

As always, my points are based on int and my polygons are counter-clockwise and not closed.

Regards
   Volker

--
Volker Schöch | vschoech_at_[hidden]<mailto:vschoech_at_[hidden]>
Senior Software Engineer
We are looking for C++ Developers: http://www.think-cell.com/career
From: Geometry [mailto:geometry-bounces_at_[hidden]] On Behalf Of Volker Schöch
Sent: Freitag, 17. Oktober 2014 16:20
To: Boost.Geometry library mailing list (geometry_at_[hidden])
Subject: [geometry] access violation in update_discarded(...)
Hi,
we have seen an access violation deep inside boost geometry. We are still working on a simple reproduction, which may take while. In the meantime, maybe you have some idea what went wrong, or some suggestion how to avoid this situation?
Here is where it happened:
template<typename Turns, typename Operations>
inline void update_discarded(Turns& turn_points, Operations& operations)
{
    // Vice-versa, set discarded to true for discarded operations;
    // AND set discarded points to true
    for (typename boost::range_iterator<Operations>::type it = boost::begin(operations);
         it != boost::end(operations);
         ++it)
    {
        if (turn_points[it->index].discarded) <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< access violation
        {
            it->discarded = true;
        }
        else if (it->discarded)
        {
            turn_points[it->index].discarded = true;
        }
    }
}
Please find the callstack attached.
Regards
   Volker
--
Volker Schöch | vschoech_at_[hidden]<mailto:vschoech_at_[hidden]>
Senior Software Engineer
We are looking for C++ Developers: http://www.think-cell.com/career
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