PhysFS you swapped the parameters

[otse]

You switched out two parameters the wrong way.

https://github.com/xarray/osgRecipes/blob/master/integrations/osgdb_physfs/ReaderWriterPhysFS.cpp#L90

PHYSFS_read( handle, &(buffer[0]), filesize, 1 ); should be 1, filesize (no joke)

Other than that, the code was outstanding, small and effective. This vfs tutorial that also uses physfs is too long and complicated. Yours is succinct and near perfect.