[Gdal-dev] OGRSpatialReference::exportToProj4 causes segmentationerror

[Xiaodong Zhang]

Hi Frank,

Thanks but please see my comments below:

Quoting Frank Warmerdam <warmerdam at pobox.com>:

> 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;

It has to be 'char *pszProjWKT' instead of double pointers, otherwise the
compile gives the following error

`OGRSpatialReference::exportToProj4 (char ***)'
/usr/local/include/ogr_spatialref.h:209: candidates are: OGRErr
OGRSpatialReference::exportToProj4
(char **) const

Is this what to be expected?

Thanks

> 
>    OGRSpatialReferenceh oProj( srcDataset->GetProjectionRef() );
> 
>    oProj.exportToProj4( &pszProjWKT );
> 
>    printf( "%s", pszProjWKT );
> 
>    CPLFree( pszProjWKT );
> 
> Best regards,
> -- 
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Programmer for Rent
>