HDF5 1.12 revised the reference datatype (class 7) in datatype message version
4: reference types 2-4 are the new H5T_STD_REF object / dataset-region /
attribute references. Datatype::parse rejected them with
InvalidReferenceType, so any dataset of that type was unreadable.
h5py cannot write this type, which is why it had never been tested. A real
file was produced by calling the libhdf5 bundled in the h5py wheel through
ctypes (H5T_STD_REF_g, H5Rcreate_object, H5Dwrite); the 2 KB result is
committed as tests/fixtures/std_ref_hdf5_2_0.h5 with its generator,
gen_std_ref.py.
- ReferenceType gains Object2, DatasetRegion2 and Attribute, accepted only
from datatype version 4.
- read_object_references decodes Object2 elements: type(1) flags(1)
token_size(1) token, zero-padded to the element size; the token is the
target's object header address. A null reference decodes to the undefined
address; an external reference, a wrong type byte or a token that doesn't
fit is an error.
The fixture test follows both references and checks they resolve to the
objects they were created from.
Co-Authored-By: Claude Fable 5.1 <[email protected]>
