osobhandClaude Opus 5.5
d110b1d945
Scale-offset (filter 6) now follows H5Z__filter_scaleoffset:
- the packed codes start at byte 21 whatever size the chunk records for
minval (libhdf5 reads min(8, size) bytes of minval and always starts the
codes at buf_offset 21). We started them after minval plus 8 bytes, so a
chunk recording a size of 0 (cve-2025-44905 /Scale_offset_short_data_be)
decoded differently from h5py;
- with a fill value defined, a code equal to the all-ones code of minbits
bits is the fill value, including minbits 0 (code 0): a chunk of nothing
but fill values read as minval;
- minbits of the full width stores the elements as they are (no minval
added), and an integer scale factor of the full width means the chunk was
left untouched; minbits or a scale factor wider than the type is an
error;
- the class parameter (integer or float) decides the decode, a scale type
that does not match it is refused, and E-scale is refused, as in libhdf5
(no library writes it; it was decoded here unchecked);
- minval is the stored bytes zero-extended, as libhdf5 reads it.
Codes past the end of the chunk stay an error, as in libhdf5 releases
after 2.0 ("Buffer too short"; 2.0 reads past the buffer, cve-2025-2308).
Shuffle (filter 2) uses its own parameter as the element size, as libhdf5
does, instead of the dataset's element size; a parameter larger than the
chunk leaves the chunk as it is (cve-2025-44905 /Shuffle_float_data_be),
and a parameter of 0 is an error.
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