osobhandClaude Opus 5.5
cab952bb00
Explains each class compare.py assigns, how ref_bugs.py confirms a ref-bug in every run and how ref.py corrects h5py's big-endian VL values (ref_fix), and records the latest result (602 of 697 ok, 3 ref-bug, 2026-09-27) with a link to CONFORMANCE.md. Mentions --no-fetch. Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
69 lines
4.3 KiB
Markdown
69 lines
4.3 KiB
Markdown
# Conformance sweep
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Reads every HDF5 file of eight public corpora with clawhdf5 and with
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h5py/libhdf5, compares the two readings object by object, and writes
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[`CONFORMANCE.md`](../CONFORMANCE.md).
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```sh
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CLAWHDF5_PYTHON=/path/to/venv/bin/python conformance/run.sh # ~30 s once the corpus is cached
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conformance/run.sh --no-fetch # use the cached corpus as is
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conformance/run.sh --update-baseline # after an intended change in results
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```
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Latest result (tank, 2026-09-27, `conformance/run.sh --no-fetch`): 602 of
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697 files ok, 0 our-error, 0 mismatch, 3 ref-bug, 92 h5py-cannot-read, and
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no panic, hang, crash or out-of-memory. The report with every file is
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[`CONFORMANCE.md`](../CONFORMANCE.md).
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## Classes
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`compare.py` puts each file in one class:
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| class | meaning |
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| **ok** | clawhdf5 and h5py read the same objects with the same values |
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| **our-error** | h5py reads something clawhdf5 refuses |
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| **mismatch** | both read it, with different values or structure |
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| **h5py-cannot-read** | h5py (libhdf5) cannot read the file; not compared |
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| **ref-bug** | h5py reads an object clawhdf5 refuses, but only through a libhdf5 over-read: `ref_bugs.py` re-reads it in six processes with different heaps (import order, `MALLOC_PERTURB_`) and its values change. The file is ref-bug only while that is confirmed in the same run; if the values become stable it counts as our-error again |
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| **panic / hang / crash / oom** | a clawhdf5 failure under the timeout and address-space limit; the gate fails on any |
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Where h5py itself returns wrong values through a known h5py bug (the
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big-endian variable-length bug: elements returned with the file's bytes
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under a little-endian dtype), `ref.py` checks that the installed h5py has
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the bug, corrects the values before hashing and marks them `ref_fix`, so
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those objects are still compared. The evidence for the three current
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ref-bug files is under "Conformance: the last non-ok files" in
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[`docs/known-issues.md`](../docs/known-issues.md).
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Needs Rust, `git`, `h5dump` (Debian/Ubuntu `hdf5-tools`), `libaec` (for the
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probe's `szip` feature; `libaec-dev`), and a Python with the packages in
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`requirements.txt`. The first run downloads about 450 MB of sparse checkouts.
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| file | role |
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|---|---|
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| `corpus.txt` | the corpora: git URL, pinned commit, swept root, sparse-checkout patterns |
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| `fetch-corpus.sh` | shallow, sparse, blob-filtered checkout of each pinned commit into `.cache/src/` (gitignored); no-op when already there |
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| `list_files.py` | which files are probed (HDF5/netCDF-4 extensions minus netCDF classic, plus the CVE reproducers) |
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| `probe/` | the clawhdf5 side: a standalone crate (outside the workspace, so `cargo test --workspace` never builds it) that walks a file with `clawhdf5-format` and prints canonical JSON |
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| `ref.py` | the h5py side: the same JSON from h5py (values corrected for a known h5py bug are marked `ref_fix`) |
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| `ref_bugs.py` | re-reads the objects h5py reads only through a libhdf5 bug in six differently-set-up processes; an object whose values change is confirmed as a libhdf5 over-read |
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| `test_ref.py` | tests of `ref.py`'s correction and `ref_bugs.py`'s confirmation (`python conformance/test_ref.py`) |
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| `run_one.sh` | runs both sides on one file (and `h5dump` on the CVE corpus) under a timeout and an address-space limit |
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| `compare.py` | classifies each file (ok / our-error / mismatch / h5py-cannot-read / ref-bug / panic / hang / crash / oom) and groups root causes |
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| `report.py` | writes `CONFORMANCE.md` |
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| `check.py` | the gate: fails on any panic/hang/crash/oom, on an ok count below `baseline.json`, or on a baseline-ok file that is no longer ok |
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| `baseline.json` | the ok files the gate holds the line on |
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| `requirements.txt` | pinned h5py / numpy / hdf5plugin / netCDF4 |
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Results for every file (both sides' JSON and stderr, `results.csv`,
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`results.json`, `summary.md`) are left in `.cache/results/`.
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The nightly job is `.gitea/workflows/conformance.yml`; it prints the report
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into the job log.
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The canonical value encoding both sides hash is documented at the top of
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`probe/src/main.rs`. Values are compared as libhdf5 presents them: a float
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with a non-IEEE bit layout (N-Bit) or an integer with a bit offset is compared
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as the converted number, not as raw file bytes.
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