[GEOT-2791] Fixed IllegalArgument in buffer when reading a sparse shape file

[DieterDePaepe]

The original implementation assumed all entries a shape file were in order, which does not hold up for sparse shape files. This resulted in an IllegalArgument when setting the buffer. This in turn resulted in not all entries being read.

This patch ensures the buffer is either addressable, or reloads it from the Channel being read.

[aaime]

Thanks for the patch. You actually have to add a test proving the patch works and making sure reading sparse files won't fail again (with a small test shapefile) in order for the change to be committed. The test should fail without the patch, and work with it.

[DieterDePaepe]

Test has been included.

[aaime]

Hi, I've spent some time last weekend looking at the patch. It looks good, and it works. However... I have a problem.
The current shapefile module is about to be retired, and replaced with shapefile-ng, a refactor of it that replaces the higher level classes (store and friends) and tries to clean up the module.
I've tried to port your patch there, but I can't make it work. At the same time, the test you provided shows shapefile-ng is affected by the problem you've reported.

Don't you happen to have some time to have a look there too, by any chance?
https://github.com/geotools/geotools/tree/master/modules/unsupported/shapefile-ng

[DieterDePaepe]

I'll try to patch up the shapefile-ng when I have some time. Hopefully somewhere next week.

[aaime]

Nice, much appreciated

[aaime]

Thank you, very good :-)