[Gdal-dev] OGRSpatialReference::exportToProj4 causes segmentation error

[Frank Warmerdam]

Xiaodong Zhang wrote:
> Hi,
> 
> One of our code, which works with Gdal 1.1.8 causes a segmentation fault with
> newer version of Gdal 1.1.9  and Gdal 1.2.1. It seemed that the following part
> causes the problem.
> 
> char ** ppProj;
> ....
> proj = srcDataset->GetProjectionRef();
> /* so far is OK after open an image with GDALOpen and get the projection info
> 
> OGRSpatialReference hProj(proj); // it is still OK up to here
> hProj.exportToProj4 (ppProj); // it crashes here
> 
> Also the OGR documentation says to de-allocate ppProj using CPLfree(), how to
> use it exactly?

Hi,

You need to pass a pointer to a pointer where the resulting string can be
assigned.  I'm not sure why it would work with 1.1.8 unless it was just a
coincidental thing about where the unitialized ppProj pointed.

It should be something like:

   char **pszProjWKT = NULL;

   OGRSpatialReferenceh oProj( srcDataset->GetProjectionRef() );

   oProj.exportToProj4( &pszProjWKT );

   printf( "%s", pszProjWKT );

   CPLFree( pszProjWKT );

Best regards,
-- 
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