GDAL DestroyFeature() method produces segmentation fault

Liam McNabb Source

I have a method which loads OGRFeature's and extracts data from them. However, when I call the method OGRFeature::DestroyFeature() to release the memory, I get a segmentation fault.

void Class::processFeatures() {
    OGRFeature* feature;
    feature = layer->GetNextFeature();
    while( feature != NULL ) {
        handleGeometries(); //Handling Geometries
        doY(); //Handling Fields
        OGRFeature::DestroyFeature(feature);
        feature = layer->GetNextFeature();
    }
}

void Class::handleGeometries() {
    OGRGeometry* geometry = feature->GetGeometryRef();
    //Some handling code
    delete geometry;
}

The code runs and saves the information if I exclude the DestroyFeature. This example does work.

#include "gdal.h"
#include "gdal_priv.h"
#include <ogrsf_frmts.h>

int main()
{
    GDALAllRegister();
    GDALDataset* map;
    map = (GDALDataset*) GDALOpenEx("shape.shp",GDAL_OF_VECTOR,NULL,NULL,NULL);

    if (map)
    {
        OGRLayer* layer = map->GetLayer(0);

        OGRFeature* feature;
        feature = layer->GetNextFeature();
        while( feature != NULL ) {
            OGRFeature::DestroyFeature(feature);
            feature = layer->GetNextFeature();
        }

        GDALClose(map);
    }

    return 0;
}

What is causing the problem? And how would I solve it?

EDIT: second example expanded

c++memory-leakssegmentation-faultgdal

Answers

answered 5 days ago G. Giordano #1

This answer comes after a series of comments/edits to the original question that lead to this conclusion:

Deleting the geometry pointer in the handleGeoemtry() method is what causes the memory violation when the DestroyFeature() function is called, as the geometry OGRFeature::GetGeometryRef() returns a reference to an object but does not transfer the ownership to the caller.

You can use the OGRFeature::StealGeoemtry to take the ownership, or simply remove the delete geometry instruction as the DestroyFeature() function will dispose of it anyway.

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