FractalHeapHeader::parse_in reads the header as one window (a second,
longer one when it holds an I/O filter pipeline); read_managed_object_in
reads direct blocks, indirect blocks (one window up to the last child
entry) and huge objects with bounded reads. The &[u8] methods are
wrappers. A huge object indexed by the huge-object v2 B-tree, which is
not converted yet, is a clean ContiguousStorageRequired error on a
backend without the whole file in memory (after the "no index" check,
so the error order is unchanged).
storage::Window (crate-internal) reads a window of a structure and
reports bounds failures exactly as the whole-file ensure_len did, and a
short read inside the file is now a Storage error rather than an EOF.
New tests: headers (with and without a filter pipeline) cut at every
length, and managed objects in a direct root and through an indirect
root, huge objects with direct IDs and tiny objects, give identical
results through a read_at-only CountingStorage.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Range-read milestone M1, first step (docs/design/range-reads.md §3(a)):
a synchronous, no_std read interface with u64 offsets, read_at returning
Cow<[u8]>, read_ranges, len and an as_contiguous fast path. Implemented
for [u8], Vec<u8>, &T, Box<T> and Arc<T>; slices serve borrowed bytes.
read_exact_at reproduces the parsers' UnexpectedEof bounds error exactly,
so converted modules keep their error values.
FormatError gains Storage(String) and ContiguousStorageRequired; it and
the facade Error are now #[non_exhaustive] (breaking for exhaustive
matches, noted in the changelog; the Python bindings' match gets a
wildcard arm).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
