open(bytes) -> H5File with kind/list/info/attrs/attrErrors/read/
readHyperslab. Numeric data comes back in the typed array of the
stored width (Int16Array for i16, BigInt64Array for i64, Float32Array
for f32/f16, ...), strings and enum names as string arrays, array
datatypes flattened with their dims appended to the shape. Compound,
reference, opaque and VL-sequence datasets are refused with an error
naming the type; nothing is returned as reinterpreted bytes.
The logic is in a plain-Rust core module, tested natively: unit tests,
and h5py_interop, which compares every dataset, hyperslab, listing and
attribute of an h5py- and a netCDF4-written file with what libhdf5
reads back (generator shared with the Node test of the built package).
No mmap, no threads; lz4 is on, zstd/szip (C) are not. A
wasm-release profile (opt-level s, LTO) serves the browser build.
ci-test.sh lints the crate for wasm32 and checks it builds no C.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
The facade already builds for the browser target without mmap (and
with it: memmap2 compiles there and File::open just fails, as std::fs
does). Nothing needed gating; keep it that way with a ci-test.sh step,
and install the target in the CI container.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
decompress_chunk_masked and compress_chunk matched on the filter ID. They
now look the ID up in filter_registry: a static table of the built-in
filters compiled into this build (a filter whose cargo feature is off is
simply absent), then the codecs an application registered at run time with
register_filter (a FilterCodec, or a plain decoding closure). Registered
codecs cannot shadow a built-in one, and their output is held to the same
per-stage bound as the built-in decoders. An ID in neither tier still fails
with UnsupportedFilter(id).
The "feature off" stub functions that returned UnsupportedFilter are gone:
the table leaves those filters out instead.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
concurrent_read reads one shared File from 1-16 threads: every dataset
in full (distinct datasets per thread) and random hyperslabs of one
dataset, over a deflate and a contiguous file it generates (or reuses
while manifest.json matches). It reports decoded MB/s and scaling
efficiency, warm or --cold (posix_fadvise) page cache, sizes the decode
pool with --decode-threads, and writes JSON.
scripts/concurrent_read_h5py.py runs the same workload on the same files
with h5py threads or spawned processes (same splitmix64 data and slab
stream, checked at spot elements), and compare_concurrent_read.py prints
one table and refuses runs with different workloads. A smoke test runs
all three end to end on tiny files (h5py half honours CLAWHDF5_PYTHON /
CLAWHDF5_REQUIRE_INTEROP).
BENCHMARKS.md gets a "Concurrent reads" section with the commands, marked
not yet measured.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
dtype() simplifies the type (no byte order, string padding or member
offsets), so callers could not decode read_selection's bytes for types
the typed read_* methods skip. raw_datatype() returns the parsed
Datatype, committed types resolved, for use with data_read.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Regenerated on tank at 10d1029: ok 467 -> 569, our-error 123 -> 14,
mismatch 15 -> 22 (six user-defined-link files moved from our-error to a
listing difference), no panics, hangs, crashes or OOM. Baseline raised.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Superblock::parse now refuses a user-block offset, and the raw read path
no longer guesses a VDS fill value. The probe looks at the file from the
superblock on and reads virtual datasets with vds::read_virtual_dataset,
the dataset's fill value and its source-derived extent.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
The test compared h5py against its own expected table, so it passed with
the fix reverted. Found by the adversarial review.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Group::attrs now leaves out an attribute it cannot decode. The agent read
its settings through it, so a store whose float16 (or compression,
quantized_index, WAL mark, signature...) attribute could not be decoded
opened with the default in its place, and no error. /meta is now read
with attrs_with_errors and any unreadable attribute is a Schema error,
as it was before attrs became tolerant. Found by the adversarial review.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Their elements are global-heap IDs and object addresses in the source
file. The VDS reader copied them raw, so anything decoding them against
the virtual dataset's file got another object's data with no error.
Same-file sources are unaffected. Found by the adversarial review.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Unlimited VDS mappings were refused, and printf-style source names
("f-%b.h5") were not expanded, so those regions read as fill (read-matrix
case 0470: 29 of 30 values wrong). All 7 virtual datasets in the libhdf5
test set use such mappings.
Implement H5Dvirtual.c's semantics in the vds module:
- %b is the block number, %% a literal %, other specifiers are an error;
block j of the virtual selection comes from the source named with j,
probing from 0 to the first missing source (printf gap 0);
- unlimited source/virtual selections are clipped to what the source's
current extent fills (H5S_hyper_get_clip_extent_match, partial last
block included);
- the extent is recomputed as H5Dget_space does (view "last available":
the largest clip, never below what limited mappings need), exposed as
vds::virtual_dataset_extent and used by Dataset::shape();
- a source in the other byte order is byte-swapped; other conversions stay
an error.
Tests: vds_interop::vds_printf_source_names,
vds_unlimited_mappings_follow_source_extents (h5py low-level API, earliest
and latest format) and vds_libhdf5_test_files (vds-eiger, 4_vds and
vds-percival-unlim-maxmin from HDF5's tools/test/testfiles/vds, committed
as fixtures) all compare shape and values with h5py; unit tests for the
clip arithmetic, name parsing and mapping rules.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
A message shared through the file's SOHM heap (H5Pset_shared_mesg_index)
is referenced by heap ID, which needs the SOHM table from the superblock
extension. Only message_data_with_sohm (used for fill values) loaded it;
resolve_shared_message passed no table, so a SOHM-shared datatype,
dataspace, filter pipeline or attribute failed with "invalid shared
message version: 2" and the dataset or attribute could not be read.
resolve_shared_message now loads the table when the reference carries a
heap ID.
Found while making attrs() tolerant: SOHM attributes turned from an
error into missing keys in the audit read matrix. With this fix all 36
SOHM cases there match h5py (datasets, fill values and attributes, every
shareable message type, libver earliest and latest).
Regression test: sohm_shared_messages_resolve (h5py writes files sharing
each message type on its own and all of them; values and attributes
checked).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
libhdf5 walks a local heap's free list when it loads the heap's data and
refuses the heap ("bad heap free list") when a free block starts or ends
outside the data segment, or links to offset 0. We never looked at the
free list, so a damaged old-style group listed names read from the broken
heap: once the user block of cve-2021-36977.h5 was applied, its root
listed eight garbage names where libhdf5 fails.
LocalHeap::validate_free_list (new) mirrors H5HL__fl_deserialize, with a
cycle bound, and accepts H5HL_FREE_NULL (1) or an all-ones head as the
end of the list. Like libhdf5 it runs when the first name is needed, not
on parse, so an empty group with a damaged heap still lists as empty
(cve-2018-13871.h5, cve-2024-29166.h5, gh-4431-poc-03.h5 keep matching
h5py).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
A file may start with a user block (h5py userblock_size, h5jam), putting
the superblock at 512, 1024, ...; every address in the file is then
relative to the superblock. The signature search found it, but every
reader passed the whole file to the parsers, so addresses landed
userblock bytes early and the root group failed with
InvalidObjectHeaderVersion (twithub.h5, twithub513.h5,
h5clear_fsm_persist_user_*.h5).
Readers now view the file from the superblock on, taking the signature's
position as the base address as libhdf5 does: File (mmap, buffered,
from_bytes), MmapFile, LazyFile, AsyncHDF5File, the VOL and MPI VOL
readers, the HNSW loader and external VDS source files. File, MmapFile
and LazyFile gain user_block_size(). The new signature::split_user_block
returns the two parts, and Superblock::parse refuses a non-zero offset
(UserBlockNotStripped) so a format-level caller cannot silently apply
superblock-relative addresses to the whole file.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
A version-1 shared message (HDF5 1.6) embeds the target as a symbol-table
entry: after six reserved bytes comes a length-sized local-heap offset,
then the object header address. We read the heap offset as the address,
so datasets using a committed datatype in 1.6-era files (tcompound.h5,
tcompound2.h5) failed with InvalidObjectHeaderVersion. parse_shared_ref
now takes length_size and skips the offset, as libhdf5 does.
Resolving a reference also no longer falls back to the first message of
any type in the target header: a missing target message is
SharedMessageTargetMissing instead of garbage.
Fixture: tcompound.h5 from libhdf5's tools/test/testfiles (8 KiB).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
HDF5 1.6 encoded a compound member that is a fixed-size array through
legacy per-member fields (dimensionality, permutation, four dimension
sizes) that the v1 decoder skipped, so a [4] i32 member read as one i32
with the wrong size. Build the array type from those fields as libhdf5
does (ignoring the permutation) and refuse more than four dimensions.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Runs conformance/run.sh in rust:latest on a schedule and on demand, with its
own venv (pinned h5py/numpy/hdf5plugin/netCDF4) and hdf5-tools. Fails on any
panic, hang, crash or OOM in clawhdf5 and on a drop against
conformance/baseline.json; prints CONFORMANCE.md into the job log and
uploads nothing. Plain git checkout, no JavaScript actions.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
conformance/run.sh fetches eight public HDF5 corpora pinned by commit
(conformance/corpus.txt) into a gitignored cache, reads every file with
clawhdf5 (conformance/probe, a crate outside the workspace) and with
h5py/libhdf5 (ref.py), and the CVE files with h5dump, each under a timeout
and an address-space limit; compare.py classifies the files, report.py
writes CONFORMANCE.md and check.py gates on panics/hangs/crashes/OOM and on
regressions against conformance/baseline.json. ~25 s once cached.
Changes from the ad-hoc audit harness:
- the probe compares non-IEEE-layout floats (N-Bit) and integers with a bit
offset or reduced precision as the values libhdf5 converts them to, not
raw file bytes: 8 files that showed as mismatches now read identically;
- ref.py exits without tearing down h5py objects: libhdf5 2.0 aborts while
freeing them for two files about half the time, which flipped them
between ok and h5py-cannot-read from run to run;
- the file list is defined (list_files.py): netCDF classic files are left
out, 11 HDF5 files the ad-hoc sweep missed are in.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Elements of a virtual dataset that no mapping supplies (unmapped regions,
a missing source file, a missing source dataset) read as 0 instead of the
fill value libhdf5 returns — silent wrong data for any VDS created with a
non-zero fillvalue (read-matrix cases 0471/0472: -1 and 7 read as 0). A
missing source dataset was an error; libhdf5 reads it as fill.
Move VDS assembly into a new vds module following H5Dvirtual.c:
vds::read_virtual_dataset takes the dataset's fill value and a
VdsFileResolver that can refuse a name, and reports how many elements were
unmapped. Sources are read with their own fill value, and a source whose
datatype differs from the virtual dataset's is an error (libhdf5 converts).
File passes the dataset's fill value, resolves source names against the
virtual file's directory, and refuses names that leave it with an error
instead of reading them as fill. read_selection on a VDS goes through the
same fill-aware path.
The raw-read API (read_raw_data_full*) has no fill value, so it now errors
for a VDS with unmapped elements instead of guessing zeros.
Tests: vds_interop::vds_unmapped_regions_read_as_fill_value (external,
same-file, missing file/dataset, sparse source with its own fill, int
fill; earliest and latest format) and
vds_source_outside_directory_is_an_error_not_fill, both against h5py;
integration_test::v4_virtual_dataset_raw_api_refuses_to_guess_the_fill_value.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
attrs() read every attribute of an object through extract_attributes_full,
so one attribute it could not read (a corrupt or unsupported attribute
message, or a heap object it could not locate) failed all of them — the
same shape as the huge-object bug, where one 8 KiB attribute hid every
attribute on a NetCDF file's root group.
- clawhdf5-format: new attribute::extract_attributes_tolerant returns the
attributes it could read plus one error per attribute it could not.
Errors in the attribute index itself (Attribute Info message, dense
heap header, B-tree) still fail, since then it is unknown which
attributes exist. extract_attributes_full is unchanged (strict); both
share one implementation.
- clawhdf5: attrs() on Group/Dataset, MmapGroup/MmapDataset and
LazyGroup/LazyDataset leaves an unreadable attribute out (documented),
and the new attrs_with_errors() returns the map with the per-attribute
errors. A value is either returned complete or not at all.
Regression test: one_unreadable_attribute_does_not_hide_the_others (h5py
writes 11 dense attributes; one message's version byte is corrupted;
before: attrs() failed with InvalidAttributeVersion(127), after: the 10
others come back with their values and one error is reported).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Group::datasets()/groups() (and the Mmap/Lazy handles) listed only hard
links, so a soft link to a dataset or group was missing, and dataset(name)
/ group(name) on a group handle could not open one. In old-style (symbol
table) groups a soft link's entry has no object header address, and the
listing failed outright trying to parse one.
The three facade handles each had their own copy of the child-listing
code; they now share group_v2::resolve_group_children, which returns hard
links plus soft links resolved to their targets (relative targets from
the group holding the link, via the new resolve_path_from). A dangling or
cyclic soft link, an external link and a user-defined link are left out —
h5py lists their names but cannot open them. Any other error met while
resolving is returned, not hidden.
Path resolution now walks a relative soft link's target from the group
holding it instead of rebuilding the path from the root (same result,
one less re-walk), and ignores "." components.
Regression test: soft_links_are_listed_as_their_targets (h5py writes
absolute, relative, group, dangling, cyclic and external links with
libver latest and earliest; listings compared with h5py for File,
MmapFile and LazyFile).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
With a 2.0 low version bound, libhdf5 stores the VDS mapping list as heap
block version 1: every entry starts with a flags byte (0x04 same file, no
file name; 0x01/0x02 file/dataset name shared with an earlier entry, whose
index is stored in place of the name). The parser treated only a leading
0x04 byte as special, so a 0x00 flags byte read as an empty (same-file)
name and shared names were read as garbage.
Decode it as H5D__virtual_load_layout does, refusing unknown flags,
forward references and block versions above 1.
Test: vds_interop::vds_mapping_block_version1_shared_names (h5py
libver=("v200","v200") with repeated long names; failed before with
"unknown dataspace selection type") plus the exact heap block as a unit
test.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
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]>
Link types 65-255 are user-defined: their target is only meaningful to
the application that registered the link class. LinkMessage::parse
rejects them with InvalidLinkType, and group traversal propagated that,
so one such link made the whole group unlistable and every path through
it unresolvable (libhdf5's tall.h5 and tudlink.h5, class 187).
Group traversal (compact and dense) now leaves user-defined links out,
the way h5py leaves out links it cannot open; reserved types (2-63) are
still an error.
Regression test: user_defined_links_do_not_break_the_listing, on
libhdf5's own tools/test/testfiles tall.h5 and tudlink.h5 (BSD-style
HDF5 licence, 10 KB and 1 KB), committed as fixtures.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
A heap ID's type is in bits 4-5 of its first byte (H5HF_ID_TYPE_MASK
0x30); bits 6-7 are the ID version. The reader took the type from bits
6-7, so every huge object ID (0x10) was decoded as a managed one and
failed — and since dense attributes are read all at once, one attribute
over the heap's 4 KiB managed limit made every attribute on its object
unreadable (netcdf4-python's issue671.nc / issue672.nc).
- Huge objects (type 1): located directly from the ID when address and
length fit in it, otherwise through the huge-object v2 B-tree (record
types 1 and 2); filtered huge objects are decoded with the heap's
pipeline and their filter mask.
- Tiny objects (type 2): read from the ID itself.
- Filtered heaps: the header's pipeline is parsed (it was skipped short,
so the header checksum was read from the wrong place), indirect-block
entries for direct blocks carry their filtered size and mask, and
direct blocks are decoded before objects are read from them.
- An unknown ID version is an error.
FractalHeapHeader gains huge_btree_address, filter_pipeline,
root_direct_block_filtered_size, root_direct_block_filter_mask,
offset_size and length_size; read_managed_object now accepts any ID type.
Regression tests (h5py-written, compared with h5py):
dense_attribute_stored_as_a_huge_heap_object, dense_group_with_a_huge_link,
dense_group_with_a_filtered_link_heap; unit tests
tiny_object_is_read_from_the_id, huge_object_with_a_direct_id,
unknown_heap_id_version_is_refused.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
A version-1 shared message reference is version, type, six reserved bytes
and then an old-style symbol table entry: link-name offset (length size),
object header address, cache type, reserved, scratch. We read the address
straight after the reserved bytes, i.e. the link-name offset, and the
committed datatype lookup failed with InvalidObjectHeaderVersion (the bytes
checked in tcompound.h5: name offset 0x10, then 0x590 = /type1). Datasets
of 1.4/1.6-era files that use a committed datatype were unreadable.
Skip the name offset. parse_shared_ref has no length size, so add
parse_shared_ref_sized and use it in every internal caller;
parse_shared_ref keeps its signature and assumes length size == offset
size. The old parse_v1_ref unit test encoded the wrong layout and now uses
the real bytes.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Compound datatype version 1 carries, per member, a dimensionality and four
dimension sizes (HDF5 before 1.4 had no array class). The parser skipped
those 28 bytes, so a member such as `f: f32[4]` came back as a single f32
at the member's offset: the compound's size was right but its members were
wrong. libhdf5 wraps such a member in an array type of the first
`dimensionality` sizes and ignores the permutation; do the same, and
reject a dimensionality above 4 as libhdf5 does.
Only files old enough to also use layout message v1 have these, so this
became reachable with the previous commit (tarrold.h5, tcompound.h5).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
HDF5 1.4/1.6-era files store the layout as version 1 or 2: version,
dimensionality, class, 5 reserved bytes, an address (contiguous and chunked
only), dimensionality 32-bit sizes (with the trailing element-size
dimension) and, for compact storage, a 32-bit size and the raw data. They
failed with InvalidLayoutVersion — 84 of the 686 files in the audit sweep,
205 datasets.
Map them onto the existing variants: chunked uses the same version-1
B-tree chunk index as version 3 and is reported as version 3, so every
chunked read path (filters, selections, caches) applies unchanged.
Contiguous size is the product of the stored dimensions, which is what
libhdf5 computes from the dataspace; a disagreement fails the reader's size
check instead of returning wrong data.
Fixtures are HDF5's own deflate.h5 (v1, chunked + deflate) and
h5ex_g_iterate.h5 (v2, contiguous, one unallocated dataset); the new
interop test compares every dataset byte for byte against h5py.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
An internal node's child pointer is an address, the child's record count
and (below the first internal level) the child subtree's total record
count. libhdf5 (H5B2__hdr_init) encodes the record count in the width of
a leaf's maximum and the subtree total in the width of cum_max_nrec for
that depth, computed level by level from the node size. The reader
guessed 2 * leaf_max and leaf_max^depth, which agree at depth 2 but not
at depth 3: a 24 000-link group's name index has depth 3, its root's
pointers were read 3 bytes wide instead of 2, and listing failed with a
garbage heap offset.
Regression tests: dense_group_with_a_three_level_name_index (h5py writes
24 000 links; listing compared with h5py) and
subtree_capacity_matches_libhdf5.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
A child indirect block in row r of a fractal heap's doubling table spans
that row's block size of heap space, so it has
log2(size) - log2(start_block_size * width) + 1 rows (libhdf5's
H5HF__dtable_size_to_rows). The reader used row - first_indirect_row + 1,
which undercounts, so every object stored past the root block's direct
rows (512 KiB with libhdf5's defaults) was unreachable: dense groups with
a few thousand long link names, or ~20 000 short ones, could not be listed.
Regression test: dense_group_whose_heap_outgrows_the_root_direct_rows
(h5py writes 2 500 links with 248-byte names; listing compared with h5py).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
CHANGELOG: upgrade notes (changed read results for max-shape files,
saturating conversions, new writer errors, format-crate API changes) and
the reader/writer correctness fixes. known-issues: the silent-wrong-data
table with before/after sweep numbers, the gaps still open, and a
correction to the Extensible Array entry, which said files we wrote were
unaffected. CLAUDE.md: clawhdf5-gpu is vector distance computation, not
I/O, and clawhdf5-filters holds only deflate backends (no Blosc).
Also a facade test that libhdf5's 20-bit N-Bit float test data reads as
libhdf5's values.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
The interop step built writer_h5py_tests without the lz4/zstd features,
so the hdf5plugin round-trips added with the registered LZ4 framing and
the Zstd content-size fix never compiled in CI, and CI never installed
hdf5plugin.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
The maxshape checks added to chunked_write use format!, which a no_std
build has to import from alloc (scripts/check-nostd.sh).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
dataset_fill_value treated a shared Fill Value message as "no fill
value", so unwritten storage of a dataset whose fill value lives in the
file's shared-message (SOHM) heap read as zeros rather than its fill
value. libhdf5 shares fill values whenever the file has a SOHM index for
them.
- fill_value::dataset_fill_value_in follows the reference (another object
header, or the SOHM heap); read_full_with_fill and the facade's
selection read use it.
- dataset_fill_value, which has no file to follow a reference into, now
returns UnresolvedSharedMessage for a shared message instead of None.
- shared_message::load_sohm_table / message_data_with_sohm load the SOHM
table from the superblock extension on demand.
- parse_sohm_table skipped each index's leading version byte, reading
every field one byte off; SOHM references could never resolve.
Fixture shared_fill_value.h5 (HDF5 2.0, gen_shared_fill.py): sohm_b read
[0,1,2,3,0,0,0,0] and now reads [0,1,2,3,-7,-7,-7,-7], as h5py does.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
libhdf5 applies filters in pipeline order, so with Fletcher32 before
deflate (h5repack_filters.h5 /dset_all: shuffle, fletcher32, deflate; or
h5py's set_fletcher32() then set_deflate()) the compressor holds the
chunk plus a 4-byte checksum. decompress_chunk bounded every stage by the
chunk size and rejected it: "deflate: output exceeds size limit". Bound
each stage by the chunk size plus 4 bytes per Fletcher32 that precedes
it in the pipeline.
Test: fletcher32_before_deflate_decodes (h5py-written chunk, and our own
shuffle + fletcher32 + deflate round trip); failed before.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Any maxshape forced chunked storage, even one equal to the shape, which
cannot grow. h5py and the library store such a dataset contiguously; we
now do too unless chunks (or a filter) are requested.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
D-scale floats were rebuilt as `minval + code / 10^D` in f64 and then
rounded to f32 once, but libhdf5 (H5Z_scaleoffset_modify_3/4 with
`float`/`powf`) computes `(float)(int)code / powf(10, D) + min` in single
precision. The two differ by 1 ULP for some values: le_data.h5
/Scale_offset_float_data_{le,be} gave 1.6663332 (0x3fd54a69) where
libhdf5 gives 1.6663333 (0x3fd54a6a). Use f32 arithmetic for 4-byte
floats and `(double)(long)code / pow(10, D) + min` for 8-byte ones.
Test: scaleoffset_float_dscale_matches_libhdf5_bits (le_data.h5 float
LE/BE and double chunks, bit-exact against h5py); failed before.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
osobh