[gdal-dev] Invalid node descriptor size in .sbn

[Even Rouault]

Le mercredi 12 février 2014 13:40:38, Dennis Gocke a écrit :
> Hi,
> 
> 
> 
> I found a problem with the shape file driver that occurs when reading
> features with a spatial filter from a large shapefile that has a spatial
> index (sbn).
> 
> 
> 
> The problem can be reproduced with this shapefile
> http://geofuse.geoeye.com/static/shp/GE1_2012.zip but it's not only this
> shapefile, I have others that show the problem, all of them are rather big.
> Recalculating the spatial index (with ArcGIS) doesn't solve the problem,
> the files seem to be valid.
> 
> 
> 
> When calling CPLGetLastError..() after the first GetNextFeature() a failure
> is returned with the message "Invalid node descriptor size in .sbn :
> 503800".
> 
> It seems one could just ignore the Failure and continue reading the
> features. Everything seems fine (although it probably did not use the
> spatial index for filtering).
> 
> Perhaps a Warning instead of a Failure would suffice.
> 
> 
> 
> The error is generated in sbnsearch.c because "nNodeDescCount> nMaxNodes".
> It seems the maximum tree depth of 15 is not enough.
> 
> Perhaps the maximum should be increased.

Yes. Fixed by http://trac.osgeo.org/gdal/ticket/5383. The limitation to 15 was 
not really justified.

> 
> 
> 
> While testing this I also noticed a strange behavior. Sometimes
> GetLastError..() returned a failure and sometimes it did not. When not
> calling layer.GetSpatialRef() before calling GetNextFeature() the first
> time no failure was returned although it still of course had problems
> reading the sbn and "hSBN->sHooks.Error( szErrorMsg );" was still called.

Hum not sure to follow you completely. But sometimes the error flag may be 
cleared. The first time you call GetSpatialRef() it reads the .prj file and I 
can see that for some reason the routine that does it clears the error flag.

> 
> 
> This happens with the current development Version, but is also there in the
> 1.10.0 Version.
> 
> Best Regards,
> 
> Dennis

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