osobhandClaude Opus 5.5
159e588550
Our checksum reduced its sums with `% 65535`; libhdf5's H5_checksum_fletcher32 folds them with `(s & 0xffff) + (s >> 16)`, which leaves 0xffff where the modulo leaves 0. On about one chunk in 32768 libhdf5 refused the chunks we wrote and we refused the chunks it wrote. Every release since v2.1.0 is affected. clawhdf5_format::checksum::fletcher32 is a port of H5_checksum_fletcher32 and the filter's only implementation. Verification also accepts the byte-swapped form libhdf5 accepts (1.6.2 and earlier) and the `% 65535` form earlier releases wrote, so their files stay readable. The new interop test compares the checksum with libhdf5's own function (ctypes) on every 1- and 2-byte input and 40 000 random and fold-heavy inputs, and moves fold-case chunks between h5py and FileBuilder/FileEditor in both directions; with the old filters.rs the three file tests fail. Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
clawhdf5-format
Pure-Rust HDF5 binary format parsing and writing — no C dependencies.
Features
- Zero-copy superblock, object header, and B-tree parsing
- Chunked dataset read/write with filter pipelines
no_stdsupport (disablestdfeature)- Optional parallel reads via Rayon
- SHA-256 provenance tracking
Usage
use clawhdf5_format::Superblock;
let data = std::fs::read("data.h5").unwrap();
let sb = Superblock::from_bytes(&data).unwrap();
println!("HDF5 version {}.{}", sb.version_major(), sb.version_minor());
License
MIT