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feat(format): decode hyperslab selection versions 1 and 2 in VDS mappings

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libhdf5 serializes a VDS hyperslab as version 1 (irregular, 4-byte block
corners) for the default format bounds, and as version 2 (regular, 8-byte)
for unlimited selections in the 1.10 format. Only version 3 was accepted,
so every h5py VDS written with default libver failed with "only version-3
hyperslab selections are supported" (5 libhdf5 test files in the sweep).

Decode all three versions following H5S__hyper_deserialize, including
irregular hyperslabs (a union of blocks, enumerated in row-major order as
libhdf5 iterates them) and the all-ones "unlimited" count/block marker.
SerializedSelection exposes the raw form for unlimited-mapping support.

Test: vds_interop::vds_version1_irregular_hyperslab_selections compares
default-libver h5py VDS reads (contiguous, strided and 2-D block mappings)
with libhdf5's values.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
This commit is contained in:
osobh
2026-09-25 21:57:32 -05:00
co-authored by Claude Opus 5.5
parent 42b81d9f1c
commit 190918a478
4 changed files with 562 additions and 104 deletions
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docs/known-issues.md
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@@ -71,7 +71,8 @@ the VDS item, which is marked.
- **Virtual datasets:**
- **Wrong data:** unmapped regions read as 0 instead of the fill value.
- `%b` printf-style source names are not expanded.
- Hyperslab selection versions 1 and 2 are refused.
- ~~Hyperslab selection versions 1 and 2 are refused.~~ Fixed 2026-09-25:
versions 1-3 and irregular hyperslabs are decoded.
- **Files with a user block:** the base address is not applied.
- **Old-style shared messages (version 1)** read the wrong address.
- **Groups and links:**