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docs: first conformance report and baseline (42b81d9, tank)
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467 of 697 files read identically to h5py 3.16 / HDF5 2.0, 123 our-error,
15 mismatch (2 an h5py big-endian VL bug), 92 libhdf5 cannot read; no
panics, hangs, crashes or OOM.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
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osobh
2026-09-25 22:06:00 -05:00
co-authored by Claude Opus 5.5
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CONFORMANCE.md
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# clawhdf5 conformance report
Every HDF5 file of eight public corpora (pinned by commit) is read twice — by
clawhdf5 (`conformance/probe`, the same `clawhdf5-format` calls the facade
makes) and by h5py/libhdf5 (`conformance/ref.py`) — and the two readings are
compared object by object: the set of hard-linked objects, each dataset's and
attribute's shape, and a SHA-256 of its values in a canonical encoding. The
CVE corpus is also run through `h5dump`. Each side runs under a timeout and an
address-space limit, so a hang, crash or runaway allocation is recorded, not
fatal. This file is generated by `conformance/run.sh`; do not edit it by hand.
## Run
| | |
|---|---|
| date | 2026-09-26 03:05 UTC |
| clawhdf5 commit | `42b81d9f1c3d9bef6050ad8a1326ac8c97f641d3` |
| machine | `tank`: AMD Ryzen 7 7800X3D 8-Core Processor, 16 CPUs, 61 GiB, Linux 7.0.0-34-generic x86_64 |
| command | `conformance/run.sh --update-baseline` |
| rustc | rustc 1.98.1 (48a229cea 2026-09-01) |
| reference | h5py 3.16.0, HDF5 2.0.0, numpy 2.5.3, hdf5plugin 7.1.0, Python 3.14.4 |
| h5dump | Version 1.14.6 (CVE corpus only) |
| limits | 20 s timeout (SIGKILL), 4096 MiB address space, per process; 16 files in parallel |
| runtime | 25 s probing + comparing (0 s fetch/build before it) |
## Results
A file's class is the first that applies:
- **panic / hang / crash / oom** — clawhdf5 panicked (caught per object or not), hit the timeout, died on a signal, or failed an allocation. The CI gate fails on any of these.
- **h5py-cannot-read** — libhdf5 could not open the file (or itself crashed or hung). Nothing to compare against; most are the deliberately malformed CVE reproducers.
- **our-error** — clawhdf5 returned an error for something h5py reads.
- **mismatch** — both read it, but the shapes, values, object set or attribute set differ.
- **ok** — every object h5py reads, clawhdf5 reads identically.
| corpus | files | ok | our-error | mismatch | h5py-cannot-read | panic | hang | crash | oom |
|---|---|---|---|---|---|---|---|---|---|
| NCAS-CMS_pyfive | 33 | 31 | 1 | 1 | 0 | 0 | 0 | 0 | 0 |
| cve_hdf5 | 147 | 87 | 17 | 11 | 32 | 0 | 0 | 0 | 0 |
| h5py_data | 4 | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| hdf5 | 466 | 300 | 103 | 3 | 60 | 0 | 0 | 0 | 0 |
| netcdf-c | 20 | 20 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| netcdf4-python | 18 | 16 | 2 | 0 | 0 | 0 | 0 | 0 | 0 |
| usnistgov_h5wasm | 5 | 5 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| xarray-data | 4 | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| **all** | **697** | **467** | **123** | **15** | **92** | **0** | **0** | **0** | **0** |
2 of the 15 mismatches are a known h5py bug, not ours (see *Known not-our-bug*).
Corpora (fetched by `conformance/fetch-corpus.sh` into the gitignored `conformance/.cache/`):
| corpus | source | commit |
|---|---|---|
| hdf5 | https://github.com/HDFGroup/hdf5 | `a3cf1ea82cc7` |
| cve_hdf5 | https://github.com/HDFGroup/cve_hdf5 | `3fd1f5ae3869` |
| netcdf-c | https://github.com/Unidata/netcdf-c | `beb7b9585273` |
| NCAS-CMS_pyfive | https://github.com/NCAS-CMS/pyfive | `8cf07b874913` |
| usnistgov_h5wasm | https://github.com/usnistgov/h5wasm | `02f6336527d2` |
| netcdf4-python | https://github.com/Unidata/netcdf4-python | `6e67576d39ae` |
| xarray-data | https://github.com/pydata/xarray-data | `a35297e9da2c` |
| h5py_data | https://github.com/h5py/h5py (`h5py/tests/data_files`) | `b2f0347c4200` |
## Panics, hangs, crashes, out-of-memory
None.
## Our-error root causes
Grouped by normalised error message. *files* counts files whose class this cause affects.
| files | objects | error | examples |
|---:|---:|---|---|
| 84 | 205 | `InvalidLayoutVersion(N)` | `cve_hdf5/cvefiles/cve-2016-4330.h5`, `cve_hdf5/cvefiles/cve-2016-4333.h5`, `cve_hdf5/cvefiles/cve-2018-11206-old.h5` (+81 more) |
| 10 | 10 | `ChunkedReadError("…")` | `cve_hdf5/cvefiles/cve-2025-2308.h5`, `hdf5/test/testfiles/bad_nbit_parms_walk.h5`, `hdf5/tools/test/testfiles/vds/1_vds.h5` (+7 more) |
| 9 | 17 | `InvalidObjectHeaderVersion(N)` | `cve_hdf5/cvefiles/cve-2021-36977.h5`, `cve_hdf5/cvefiles/unknown-1.h5`, `hdf5/tools/test/testfiles/h5clear_fsm_persist_user_equal.h5` (+6 more) |
| 6 | 6 | `UnsupportedFilter(N)` | `hdf5/HDF5Examples/C/H5FLT/tfiles/h5ex_d_blosc.h5`, `hdf5/HDF5Examples/C/H5FLT/tfiles/h5ex_d_blosc2.h5`, `hdf5/HDF5Examples/C/H5FLT/tfiles/h5ex_d_bshuf.h5` (+3 more) |
| 6 | 6 | `InvalidLinkType(N)` | `hdf5/tools/test/testfiles/bigendian/tall.h5`, `hdf5/tools/test/testfiles/h5diff_types.h5`, `hdf5/tools/test/testfiles/tall.h5` (+3 more) |
| 5 | 5 | `UnexpectedEof { expected: N, available: N }` | `NCAS-CMS_pyfive/tests/data/cmip_bad_eg.nc`, `cve_hdf5/cvefiles/cve-2019-9151.h5`, `hdf5/tools/test/testfiles/h5stat_newgrat.h5` (+2 more) |
| 3 | 3 | `DataSizeMismatch { expected: N, actual: N }` | `cve_hdf5/cvefiles/cve-2020-18494.h5`, `cve_hdf5/cvefiles/cve-2024-32623.h5`, `cve_hdf5/cvefiles/cve-2025-2309.h5` |
| 1 | 1 | `MissingMessage(Dataspace)` | `cve_hdf5/cvefiles/cve-2024-33874.h5` |
| 1 | 2 | `InvalidSharedMessageVersion(N)` | `hdf5/tools/test/testfiles/h5stat_tsohm.h5` |
## Mismatch root causes
| files | objects | cause | examples |
|---:|---:|---|---|
| 9 | 27 | `missing-object` | `cve_hdf5/cvefiles/cve-2019-8397.h5`, `cve_hdf5/cvefiles/cve-2019-8398.h5`, `cve_hdf5/cvefiles/cve-2021-46243.h5` (+6 more) |
| 5 | 11 | `extra-object` | `cve_hdf5/cvefiles/cve-2021-46244.h5`, `cve_hdf5/cvefiles/cve-2024-32613.h5`, `cve_hdf5/cvefiles/cve-2024-32616.h5` (+2 more) |
| 3 | 7 | `extra-attr` | `cve_hdf5/cvefiles/cve-2018-17438`, `cve_hdf5/cvefiles/cve-2018-17439`, `cve_hdf5/cvefiles/cve-2024-33874.h5` |
| 2 | 4 | `missing-attr` | `hdf5/tools/test/testfiles/twithub.h5`, `hdf5/tools/test/testfiles/twithub513.h5` |
| 1 | 1 | `attr-values: ours=vlen(>u8) h5py=object layout=- filters=-` | `NCAS-CMS_pyfive/tests/data/attr_datatypes.hdf5` |
| 1 | 1 | `values: ours=<f4 h5py=float32 layout=chunked filters=-` | `cve_hdf5/cvefiles/cve-2025-44904.h5` |
| 1 | 1 | `values: ours=>i2 h5py=>i2 layout=chunked filters=[6]` | `cve_hdf5/cvefiles/cve-2025-44905.h5` |
| 1 | 1 | `values: ours=>f4 h5py=>f4 layout=chunked filters=[2]` | `cve_hdf5/cvefiles/cve-2025-44905.h5` |
| 1 | 1 | `values: ours=<f4 h5py=float32 layout=chunked filters=[2]` | `cve_hdf5/cvefiles/cve-2025-44905.h5` |
| 1 | 1 | `values: ours=vlen({r:>f4,i:>f4}8) h5py=object layout=contiguous filters=-` | `hdf5/tools/test/testfiles/tcomplex_be.h5` |
## CVE corpus: clawhdf5 vs h5dump vs h5py
The 147 files of [HDFGroup/cve_hdf5](https://github.com/HDFGroup/cve_hdf5) — reproducers for
published libhdf5 CVEs and fuzzer finds. *read* = produced output (possibly with per-object
errors), *error* = refused cleanly. h5dump exits non-zero on any error anywhere in a file, so
its read/error split is not comparable with the other two rows; the panic, crash, hang and oom
columns are.
| tool | read | error | panic | crash | hang | oom |
|---|---:|---:|---:|---:|---:|---:|
| clawhdf5 | 142 | 5 | 0 | 0 | 0 | 0 |
| h5dump 1.14.6 | 16 | 129 | 0 | 2 | 0 | 0 |
| h5py 3.16.0 / HDF5 2.0.0 | 115 | 31 | 0 | 1 | 0 | 0 |
<details><summary>Per-file outcomes</summary>
| file | h5dump | h5py | clawhdf5 | class |
|---|---|---|---|---|
| cvefiles/cve-2016-4330.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 2 errors | our-error |
| cvefiles/cve-2016-4331.h5 | error exit | read 25 obj, 1 errors | read 25 obj, 1 errors | ok |
| cvefiles/cve-2016-4332-mtime-new.h5 | error exit | read 25 obj, 1 errors | read 25 obj | ok |
| cvefiles/cve-2016-4332-mtime.h5 | error exit | read 4 obj, 3 errors | read 4 obj, 1 errors | ok |
| cvefiles/cve-2016-4332-stab.h5 | error exit | open error | read 65 obj | h5py-cannot-read |
| cvefiles/cve-2016-4333.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 2 errors | our-error |
| cvefiles/cve-2017-17505.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2017-17506.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2017-17507.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2017-17508.h5 | error exit | read 2 obj, 1 errors | read 2 obj | ok |
| cvefiles/cve-2017-17509.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2018-11202.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2018-11203.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2018-11204.h5 | error exit | read 2 obj, 1 errors | read 2 obj | ok |
| cvefiles/cve-2018-11205.h5 | error exit | read 2 obj, 1 errors | read 2 obj | ok |
| cvefiles/cve-2018-11206-new.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2018-11206-old.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 2 errors | our-error |
| cvefiles/cve-2018-11207.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2018-13866.h5 | error exit | open error | open error | h5py-cannot-read |
| cvefiles/cve-2018-13867.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2018-13868.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 2 errors | our-error |
| cvefiles/cve-2018-13869.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2018-13870.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2018-13871.h5 | error exit | read 2 obj | read 2 obj | ok |
| cvefiles/cve-2018-13872.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2018-13873.h5 | error exit | read 1 obj, 1 errors | read 1 obj | ok |
| cvefiles/cve-2018-13874.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2018-13875.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 2 errors | our-error |
| cvefiles/cve-2018-13876.h5 | error exit | open error | read 2 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2018-14031.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 2 errors | our-error |
| cvefiles/cve-2018-14033.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2018-14034.h5 | error exit | read 1 obj, 2 errors | read 1 obj | ok |
| cvefiles/cve-2018-14035.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 2 errors | our-error |
| cvefiles/cve-2018-14460.h5 | error exit | read 3 obj, 2 errors | read 3 obj, 2 errors | ok |
| cvefiles/cve-2018-15671.h5 | ok | read 1 obj | read 1 obj | ok |
| cvefiles/cve-2018-15672.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2018-16438.h5 | error exit | read 1 obj, 1 errors | read 1 obj | ok |
| cvefiles/cve-2018-17233.h5 | error exit | read 6 obj, 1 errors | read 6 obj, 1 errors | ok |
| cvefiles/cve-2018-17234.h5 | error exit | read 6 obj, 1 errors | read 6 obj, 1 errors | ok |
| cvefiles/cve-2018-17237.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2018-17432.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2018-17433 | error exit | open error | open error | h5py-cannot-read |
| cvefiles/cve-2018-17434.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2018-17435.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2018-17436 | error exit | open error | open error | h5py-cannot-read |
| cvefiles/cve-2018-17437.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2018-17438 | error exit | read 3 obj, 1 errors | read 3 obj, 1 errors | mismatch |
| cvefiles/cve-2018-17439 | error exit | read 3 obj, 1 errors | read 3 obj, 1 errors | mismatch |
| cvefiles/cve-2019-8396.h5 | error exit | read 3 obj, 2 errors | read 3 obj, 2 errors | ok |
| cvefiles/cve-2019-8397.h5 | error exit | read 3 obj, 2 errors | read 2 obj, 1 errors | mismatch |
| cvefiles/cve-2019-8398.h5 | error exit | read 3 obj, 2 errors | read 2 obj, 1 errors | mismatch |
| cvefiles/cve-2019-9151.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 2 errors | our-error |
| cvefiles/cve-2019-9152.h5 | error exit | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2020-10809 | error exit | open error | open error | h5py-cannot-read |
| cvefiles/cve-2020-10810.h5 | error exit | open error | read 2 obj | h5py-cannot-read |
| cvefiles/cve-2020-10811.h5 | error exit | read 25 obj, 1 errors | read 25 obj, 1 errors | ok |
| cvefiles/cve-2020-10812.h5 | error exit | open error | read 2 obj | h5py-cannot-read |
| cvefiles/cve-2020-18232.h5 | error exit | read 3 obj, 2 errors | read 3 obj, 2 errors | ok |
| cvefiles/cve-2020-18494.h5 | ok | read 2 obj | read 2 obj, 1 errors | our-error |
| cvefiles/cve-2021-36977.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | our-error |
| cvefiles/cve-2021-37501.h5 | error exit | read 18 obj, 1 errors | read 18 obj, 1 errors | ok |
| cvefiles/cve-2021-45829.h5 | error exit | read 1 obj, 2 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2021-45830.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2021-45833.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2021-46242.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2021-46243.h5 | error exit | read 3 obj, 2 errors | read 2 obj, 1 errors | mismatch |
| cvefiles/cve-2021-46244.h5 | error exit | read 2 obj, 1 errors | read 6 obj, 3 errors | mismatch |
| cvefiles/cve-2024-29157.h5 | error exit | read 4 obj, 7 errors | read 4 obj, 7 errors | ok |
| cvefiles/cve-2024-29158.h5 | ok | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2024-29159.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2024-29160.h5 | error exit | read 4 obj, 1 errors | read 4 obj, 1 errors | ok |
| cvefiles/cve-2024-29161.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 2 errors | ok |
| cvefiles/cve-2024-29162.h5 | error exit | read 17 obj, 4 errors | read 17 obj, 3 errors | ok |
| cvefiles/cve-2024-29163.h5 | error exit | read 7 obj, 1 errors | read 7 obj, 1 errors | ok |
| cvefiles/cve-2024-29164.h5 | ok | read 3 obj | read 3 obj, 2 errors | our-error |
| cvefiles/cve-2024-29165.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2024-29166.h5 | error exit | read 17 obj, 2 errors | read 17 obj | ok |
| cvefiles/cve-2024-32605.h5 | ok | read 6 obj, 1 errors | read 6 obj, 1 errors | ok |
| cvefiles/cve-2024-32606.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2024-32607-1.h5 | ok | read 10 obj | read 10 obj | ok |
| cvefiles/cve-2024-32607-2.h5 | error exit | read 9 obj, 1 errors | read 9 obj, 1 errors | ok |
| cvefiles/cve-2024-32608.h5 | error exit | read 6 obj, 1 errors | read 6 obj | ok |
| cvefiles/cve-2024-32609.h5 | error exit | SIGSEGV | read 4 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2024-32610.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/cve-2024-32611.h5 | ok | read 6 obj | read 6 obj | ok |
| cvefiles/cve-2024-32612.h5 | ok | read 3 obj | read 3 obj, 2 errors | our-error |
| cvefiles/cve-2024-32613.h5 | error exit | read 7 obj, 1 errors | read 11 obj | mismatch |
| cvefiles/cve-2024-32614.h5 | error exit | read 25 obj, 2 errors | read 25 obj, 1 errors | ok |
| cvefiles/cve-2024-32615.h5 | error exit | read 4 obj, 1 errors | read 4 obj, 1 errors | ok |
| cvefiles/cve-2024-32616.h5 | error exit | read 10 obj, 7 errors | read 11 obj, 6 errors | mismatch |
| cvefiles/cve-2024-32617.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2024-32618.h5 | error exit | read 4 obj, 2 errors | read 3 obj | mismatch |
| cvefiles/cve-2024-32619.h5 | error exit | read 3 obj, 2 errors | read 3 obj | ok |
| cvefiles/cve-2024-32620.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2024-32621.h5 | ok | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2024-32622.h5 | ok | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2024-32623.h5 | ok | read 6 obj | read 6 obj, 1 errors | our-error |
| cvefiles/cve-2024-32624.h5 | error exit | read 6 obj, 1 errors | read 6 obj | ok |
| cvefiles/cve-2024-33873.h5 | error exit | read 4 obj, 1 errors | read 4 obj | ok |
| cvefiles/cve-2024-33874.h5 | ok | read 6 obj, 1 errors | read 6 obj, 1 errors | our-error |
| cvefiles/cve-2024-33875.h5 | ok | read 2 obj | read 2 obj | ok |
| cvefiles/cve-2024-33876.h5 | ok | read 3 obj, 1 errors | read 3 obj, 1 errors | ok |
| cvefiles/cve-2024-33877.h5 | error exit | read 8 obj, 1 errors | read 8 obj, 1 errors | ok |
| cvefiles/cve-2025-2153.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-2308.h5 | error exit | read 25 obj, 1 errors | read 25 obj, 2 errors | our-error |
| cvefiles/cve-2025-2309.h5 | ok | read 6 obj, 1 errors | read 6 obj, 1 errors | our-error |
| cvefiles/cve-2025-2310.h5 | error exit | read 24 obj, 8 errors | read 24 obj, 8 errors | ok |
| cvefiles/cve-2025-2912.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-2913.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-2914.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-2915.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-2923.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-2924.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2025-2925.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2025-2926.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-44904.h5 | error exit | read 25 obj, 1 errors | read 25 obj, 1 errors | mismatch |
| cvefiles/cve-2025-44905.h5 | error exit | read 25 obj, 3 errors | read 25 obj, 3 errors | mismatch |
| cvefiles/cve-2025-6269-1.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2025-6269-2.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2025-6269-3.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2025-6269-4.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2025-6270-1.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-6270-2.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-6270-3.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-6516.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2025-6750.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-6816.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-6817.h5 | error exit | open error | read 1 obj | h5py-cannot-read |
| cvefiles/cve-2025-6818.h5 | error exit | open error | read 1 obj | h5py-cannot-read |
| cvefiles/cve-2025-6856.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-6857.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2025-6858.h5 | SIGSEGV | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-7067.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2025-7068.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2025-7069.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| cvefiles/cve-2026-26200.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| cvefiles/cve-2026-34734.h5 | error exit | read 2 obj, 1 errors | read 2 obj | ok |
| cvefiles/cve-2026-92627.h5 | error exit | read 2 obj, 1 errors | read 2 obj, 1 errors | ok |
| cvefiles/unknown-1.h5 | error exit | read 11 obj, 1 errors | read 11 obj, 5 errors | our-error |
| fuzzerfiles/gh-4431-poc-03.h5 | error exit | read 1 obj | read 1 obj | ok |
| fuzzerfiles/gh-4432-poc-05.h5 | SIGSEGV | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| fuzzerfiles/gh-4433-poc-08.h5 | error exit | read 1 obj, 1 errors | read 1 obj | ok |
| fuzzerfiles/gh-4434-poc-09.h5 | error exit | open error | read 1 obj, 1 errors | h5py-cannot-read |
| fuzzerfiles/gh-4435-poc-10.h5 | error exit | read 1 obj, 1 errors | read 1 obj, 1 errors | ok |
| fuzzerfiles/gh-4585.h5 | error exit | open error | open error | h5py-cannot-read |
| fuzzerfiles/gh_2649_flawed.h5 | error exit | read 9 obj, 1 errors | read 9 obj, 1 errors | ok |
| fuzzerfiles/gh_2649_plain_model.h5 | ok | read 10 obj | read 10 obj | ok |
</details>
## Known not-our-bug
- **h5py big-endian variable-length sequences.** h5py returns the elements of a VL sequence
whose base type is big-endian with the file's big-endian bytes but a native (little-endian)
numpy dtype, so the values it reports are byte-swapped garbage; `h5dump` prints the values
clawhdf5 reads. Reproducer: `h5py.vlen_dtype(np.dtype('>f4'))` dataset holding `[1.0, 2.0]`
reads back in h5py as `[4.6e-41, 9.0e-44]`. Affected here: `NCAS-CMS_pyfive/tests/data/attr_datatypes.hdf5`, `hdf5/tools/test/testfiles/tcomplex_be.h5`.
- **Non-IEEE floats and partial-precision integers (N-Bit).** libhdf5 converts a float whose
bit layout is not IEEE (e.g. `H5Tset_precision` for the N-Bit filter) or an integer with a
bit offset / reduced precision into the plain numpy type of the same size. The probe
compares such values as converted numbers, not raw file bytes (before 2026-09-25 it compared
raw bytes, which reported every N-Bit float dataset as a mismatch).
- **Types h5py widens.** Where h5py reads a type into a numpy type of a different size
(FP8 -> float16, bfloat16 -> float32, x87 long double -> float128) the values are not
compared (shape and presence still are): dataset file type size 1 -> numpy float16 (2) (15x), attr file type size 1 -> numpy float16 (2) (15x), dataset file type size 2 -> numpy float32 (4) (2x), dataset file type size 8 -> numpy float128 (16) (1x), dataset file type size 12 -> numpy float128 (16) (1x), attr file type size 2 -> numpy float32 (4) (1x), dataset file type size 2 -> numpy >f4 (4) (1x), attr file type size 2 -> numpy >f4 (4) (1x).
- **References** are compared by presence only (`R`), not by target.
## Objects h5py fails on but clawhdf5 reads
- 19 x `OSError: Can't synchronously read data (no appropriate function for conversion path)`
- 17 x `KeyError: '…'`
- 1 x `TypeError: unhandled dtype kind M (dtype('…'))`
- 1 x `OSError: Can't synchronously read data (bad coordinate offset)`
- 1 x `KeyError: "…"`
- 1 x `ValueError: Insufficient precision in available types to represent (N, N, N, N, N)`
## Reproduce
```sh
# needs: Rust, python3 with h5py numpy hdf5plugin (conformance/requirements.txt), h5dump (hdf5-tools), git
CLAWHDF5_PYTHON=/path/to/venv/bin/python conformance/run.sh
```
The corpus (about 450 MB of sparse checkouts) is cached in `conformance/.cache/`; results for
every file, both sides' raw JSON and stderr, are in `conformance/.cache/results/`.
`conformance/baseline.json` holds the ok files the nightly CI job (`.gitea/workflows/conformance.yml`)
must keep; `conformance/run.sh --update-baseline` rewrites it.