Port ZSTD_seqStore_resolveOffCodes and its repcode-resolution helper to Rust. The C shim keeps Repcodes_t and SeqStore_t ownership in the compressor context while Rust preserves long-literal handling, mismatch materialization, and independent decoder/compressor history updates.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression (208 tests)
- cargo clippy --manifest-path rust/Cargo.toml
- cargo clippy --manifest-path rust/Cargo.toml --benches
- cargo clippy --manifest-path rust/Cargo.toml --tests
- make -B -C lib -j2 lib
Replace the shared C raw and one-byte RLE fallback block serializers with Rust ABI leaves. Preserve the zstd block headers, payload copies, capacity errors, and all existing C compressor dispatch and context ownership; share the raw serializer with the Rust one-shot path.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression (208 tests)
- cargo clippy --manifest-path rust/Cargo.toml
- cargo clippy --manifest-path rust/Cargo.toml --benches
- cargo clippy --manifest-path rust/Cargo.toml --tests
- make -B -C lib -j2 lib
Port the scalar frame-finalization policy and byte serialization into the Rust compression leaf while keeping checksum finalization, tracing, and the compression context in C. Preserve the init-to-ongoing transition on partial failure and reset the stage only after a successful epilogue.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression
- cargo clippy --manifest-path rust/Cargo.toml
- cargo clippy --manifest-path rust/Cargo.toml --benches
- cargo clippy --manifest-path rust/Cargo.toml --tests
- make -B -C lib -j2 lib
- make -B -C tests -j2 test-zstream (84 deterministic, 6737 and 9012 fuzzer cases)
Port the external-sequence window, offset, and minimum-match checks through a scalar C ABI leaf while retaining the C caller's control flow and diagnostics.
Test Plan: cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression; cargo clippy --manifest-path rust/Cargo.toml; cargo clippy --manifest-path rust/Cargo.toml --benches; cargo clippy --manifest-path rust/Cargo.toml --tests; make -B -C lib -j2 lib; make -B -C tests -j2 test-zstream (84 deterministic, 7063 and 8665 fuzzer cases).
Move ZSTD_isUpdateAuthorized behind the existing Rust parameter API while retaining the C context-stage checks, diagnostics, and mutation flow.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression (187 tests)
- cargo clippy for library, benches, and tests
- make -B -C lib -j2 lib
Move hash-salt mixing and context-reset overflow predicates behind scalar Rust ABI shims. Keep the C-owned match state and window arithmetic in the C wrapper while preserving exact architecture-dependent thresholds.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression (186 tests)
- cargo clippy for library, benches, tests, and CLI all-targets
- make -B -C lib -j2 lib
- make -B -C tests -j2 test-zstream (84 deterministic tests; fuzzers 6451 and 9879 cases)
Move target block-size and block-splitter policy predicates behind narrow Rust ABI shims while retaining the C debug logging, finalized-mode assertion, and surrounding control flow.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression
- cargo clippy --manifest-path rust/Cargo.toml and native library build
- make -B -C tests -j2 test-zstream (84 deterministic tests; fuzzers 6778 and 8299 cases)
Move construction of the external-dictionary and active-prefix ranges into a narrow Rust ABI while retaining the C window and logging surface. Preserve byte-range half-open overlap semantics and leave the input-range overlap wrapper available to its other C caller.
Test Plan: cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression (180 passed); root and CLI clippy; make -B -C lib -j2 lib; make -C tests -j2 test-cli-tests (41 passed); make -B -C tests -j2 test-zstream (84 named tests plus 6,845 and 9,628 fuzz cases passed).
Port the 16-cell match-table reduction leaf while preserving the window-index threshold, wrapping subtraction, and btlazy2 unsorted marker. Keep ZSTD_reduceIndex and its strategy-specific table selection in C behind the narrow Rust ABI.
Test Plan: cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression (180 passed); root clippy, bench clippy, and test clippy; make -B -C lib -j2 lib; make -B -C tests -j2 test-zstream (84 named tests plus 6,845 and 9,628 fuzz cases passed).
Port repcode offBase finalization and explicit-delimiter block sizing through the Rust compression ABI. Preserve wrapped sequence arithmetic, external-sequence error codes, and the no-delimiter target-size policy while keeping the C control flow intact.
Test Plan: cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression (176 passed); cargo clippy root, benches, and tests; make -B -C lib -j2 lib; make -B -C tests -j2 test-zstream (84 named tests plus 6,230 and 8,598 fuzz cases passed).
Move sequence-store byte accounting, chunk derivation, and repcode resolution into the Rust compression module. Move MT raw-sequence buffer conversions into Rust while preserving the existing C adapters and ABI layouts.
Test Plan:\n- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression\n- cargo clippy --manifest-path rust/Cargo.toml\n- cargo clippy --manifest-path rust/Cargo.toml --benches\n- cargo clippy --manifest-path rust/Cargo.toml --tests\n- make -B -C lib -j2 lib\n- make -B -C tests -j2 test-cli-tests
Route public CCtx parameter bounds through the Rust policy implementation while keeping build-specific MT limits supplied by the C configuration. Preserve clamping and validation behavior for migrated parameters and add focused Rust coverage.
Test Plan: cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression; cargo clippy --manifest-path rust/Cargo.toml; cargo clippy --manifest-path rust/Cargo.toml --benches; cargo clippy --manifest-path rust/Cargo.toml --tests; make -B -C lib -j2 lib; make -B -C tests -j2 test-cli-tests; make -B -C tests -j2 test-zstream
Move ZSTD_CCtxParams_init_advanced and its default-resolution policy into the Rust parameter API while retaining the C public ABI wrapper. Preserve validation, zeroing, and the existing row-match, block-splitter, LDM, and repcode defaults.
Test Plan:\n- cargo clippy --manifest-path rust/Cargo.toml\n- cargo clippy --manifest-path rust/Cargo.toml --benches\n- cargo clippy --manifest-path rust/Cargo.toml --tests\n- cargo +nightly fmt --manifest-path rust/Cargo.toml --all -- --check\n- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression zstd_compress_params_api\n- make -B -C lib -j2 lib
Move CCtx_params allocation, initialization, and release behind Rust ABI helpers while preserving the public C wrappers and custom allocator contract. Keep parameter bounds and policy in the existing C implementation.
Test Plan:\n- cargo clippy --manifest-path rust/Cargo.toml\n- cargo clippy --manifest-path rust/Cargo.toml --benches\n- cargo clippy --manifest-path rust/Cargo.toml --tests\n- cargo +nightly fmt --manifest-path rust/Cargo.toml --all\n- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression\n- make -B -C lib -j2 lib\n- make -B -C tests -j2 test-rust-lib-smoke\n- make -B -C tests -j2 test-zstream\n- make -B -C tests -j2 test-cli-tests
Match the original optimal-parser statistics for zero-possible symbols, complete the shortest-path fallback when the forward pass runs past its final position, and refresh the projected window state for the ultra2 second pass. Keep the simple Rust frame leaf restricted to the match finders it implements so lazy and optimal strategies retain their stateful lifecycle.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression (135 passed)
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression zstd_opt (3 passed)
- make -B -C tests -j2 test-cli-tests (41 passed)
- make -B -C tests -j2 test-zstream (84 named tests and fuzzer suites passed)
- cargo clippy --manifest-path rust/Cargo.toml
- cargo clippy --manifest-path rust/Cargo.toml --benches
- cargo clippy --manifest-path rust/Cargo.toml --tests
Route ordinary complete-input ZSTD_compressStream2 calls through the Rust frame compressor while retaining the C state machine for partial, advanced, and dictionary-backed streams. Track explicit maxBlockSize requests so the migrated path preserves the original byte-identical default behavior, and extend the C archive smoke test across context reuse and fallback cases.
Test Plan:
- cargo clippy --manifest-path rust/Cargo.toml
- cargo clippy --manifest-path rust/Cargo.toml --benches
- cargo clippy --manifest-path rust/Cargo.toml --tests
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression (133 passed)
- make -B -C tests -j2 test-rust-lib-smoke and ./tests/rustLibSmoke
- make -B -C tests -j2 test-zstream (passed, including both APIs and maxBlockSize case 78)
The multithreaded compressor already uses Rust-owned buffer and CCtx pools,
but zstdmt_compress.c still allocated and freed its job table directly. Move
the raw table storage and power-of-two sizing behind Rust's custom allocator
ABI. Keep descriptor field access and platform mutex/condition initialization
in C because those layouts remain private and platform-specific. The C
wrapper initializes and destroys synchronization primitives around the Rust
storage calls, preserving failure cleanup while leaving worker job setup,
scheduling, and stream entry points in C as the fallback implementation.
Keep the Rust storage-only ABI free of MT-only C references so single-threaded
archives can omit zstdmt_compress.c without acquiring new unresolved symbols.
Test Plan:
- `cargo test --manifest-path rust/Cargo.toml --no-default-features
--features compression zstdmt_compress --lib` -- passed (5 tests).
- `make -B -C lib lib-mt` -- passed.
- `make -B -C tests -j2 fullbench zstreamtest poolTests` -- passed.
- `./poolTests` -- passed.
- `./fullbench -i1 -B1000 README.md` -- passed, including -T2 scenarios.
- Rebuilt `programs/zstd` and ran a `-T2` compress/decompress `cmp` round-trip
-- passed.
- `rustfmt` and `cargo +nightly fmt --manifest-path rust/Cargo.toml --all
-- --check` -- passed.
- Full `cargo clippy -D warnings` remains blocked by unrelated warnings in
the concurrent `rust/src/fileio_asyncio.rs` worktree changes.
- `./zstreamtest -T5s` reaches an unrelated single-thread maxBlockSize
assertion at `tests/zstreamtest.c:2157`; MT fullbench and CLI smoke pass.
Dispatch ordinary dictionary-free ZSTD_compress2 calls through the Rust frame
compressor while retaining the original C implementation for advanced
contexts. Prepare the C workspace first so allocation downsizing and
static-context limits remain observable.
Mark successful Rust frames so a following one-shot
ZSTD_compressStream2(..., ZSTD_e_end) call uses the same output path. Other
streaming directives and advanced parameters remain on the C implementation.
Test Plan:
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo test --manifest-path
rust/Cargo.toml --no-default-features --features compression
zstd_compress::tests
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo clippy --manifest-path
rust/Cargo.toml --no-default-features --features compression -- -D warnings
- cargo +nightly fmt --manifest-path rust/Cargo.toml -- --check
- make -B -C tests fuzzer
- ./tests/fuzzer -t114 -i1000 --no-big-tests -s1
The basic fuzzer run now reaches the existing Rust one-shot compression-ratio
limit at test 113; the new stateful reuse tests pass before that point.
Move ZSTD_compressCCtx() onto the Rust frame-compression path while
retaining only the C-owned reset needed for its private context layout.
The simple API ignores advanced context parameters by contract, so the
Rust entry point can share the one-shot implementation after reset.
Preserve valid frames when the Rust superblock leaf declines a compressed
block by emitting a raw block instead. Match the fast-strategy literal
policy for negative levels so compatibility behavior remains intact.
Streaming, stateful ZSTD_compress2(), and multithreaded context
orchestration remain C-owned for a later slice. The full fuzzer currently
reaches an existing compress2() superblock-expansion failure after these
simple-API checks; that stateful path is intentionally out of scope here.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --no-default-features
--features compression zstd_compress::tests
- cargo clippy --manifest-path rust/Cargo.toml -- -D warnings
(library, benches, and tests)
- cargo +nightly fmt --manifest-path rust/Cargo.toml -- --check
- make -B -C programs zstd V=1
- make -B -C examples multiple_simple_compression
- ./multiple_simple_compression README.md ../rust/README.md
Move the frozen v0.7 decoder, dictionary handling, bufferless streaming,
and buffered streaming implementation into the Rust legacy module. Keep
the historical C translation unit as a declaration-only ABI shim so the
existing C callers and build selection remain unchanged.
The port preserves the v0.7 entropy and frame boundaries, while fixing the
Rust-side literal-tail bookkeeping and making buffered header loading revisit
the complete frame header before sizing its rolling buffers.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features decompression,legacy-v07 legacy::zstd_v07::tests
- cargo clippy --manifest-path rust/Cargo.toml -- -D warnings
- make -B -C programs zstd V=1
- decode a v0.7.5 fixture and compare its 200000-byte output
- make -C tests check V=1
Replace the v0.5 and v0.6 legacy decoder translation units with Rust modules
and keep only narrow C registration shims for the public legacy dispatch ABI.
Test Plan:
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo test --manifest-path rust/Cargo.toml --features compression,decompression,dict-builder,legacy-v05,legacy-v06,legacy-v07
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo clippy --manifest-path rust/Cargo.toml --all-targets --features compression,decompression,dict-builder,legacy-v05,legacy-v06,legacy-v07 -- -D warnings
- make -C tests check V=1
Move the frozen v0.4 frame, entropy, streaming, and dictionary decoder
implementation to Rust while retaining the C translation unit as an ABI
anchor. Register the decoder behind the matching legacy feature and keep its
historical behavior isolated from newer formats.
Test Plan:
- rustfmt +nightly --check --edition 2021 rust/src/legacy/zstd_v04.rs rust/src/legacy/mod.rs
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo test --manifest-path rust/Cargo.toml --no-default-features --features decompression,legacy-v04 legacy::zstd_v04
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo clippy --manifest-path rust/Cargo.toml --all-targets --no-default-features --features decompression,legacy-v04 -- -D warnings
- C/Rust v0.4 ABI and decompression build checks
- git diff --cached --check
Move FastCover parameter validation, corpus preparation, optimization, and
dictionary training into Rust. Retain the C source as a static-linking ABI
anchor and register the implementation with the compression dictionary-builder
feature set.
Test Plan:
- rustfmt +nightly --check --edition 2021 rust/src/dict_builder_fastcover.rs rust/src/lib.rs
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo clippy --manifest-path rust/Cargo.toml --all-targets --no-default-features --features compression,dict-builder -- -D warnings
- FastCover focused Rust tests and deterministic C-reference harness
- git diff --cached --check
Move the public ZDICT helpers, legacy trainer, dictionary finalization,
entropy-table construction, and supporting dictionary logic into Rust. Keep
the C translation unit as an ABI anchor and register the Rust module only
when compression and dictionary-builder features are enabled.
Test Plan:
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo test --manifest-path rust/Cargo.toml dict_builder_zdict
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
- rustfmt +nightly --check --edition 2021 rust/src/dict_builder_zdict.rs rust/src/lib.rs
- git diff --cached --check
Move the frozen v0.3 frame decoder, entropy tables, and streaming context
state into a feature-gated Rust module. Keep the historical C translation
unit as an ABI shim so existing C callers retain the opaque context and
error-code contracts while v0.4 and newer decoders remain unchanged.
Test Plan:
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo test --manifest-path
rust/Cargo.toml --no-default-features --features legacy-v01,legacy-v02,
legacy-v03
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo test --manifest-path
rust/Cargo.toml --no-default-features --features compression,decompression,
dict-builder,legacy-v01,legacy-v02,legacy-v03
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo clippy --manifest-path
rust/Cargo.toml --all-targets --no-default-features --features
compression,decompression,dict-builder,legacy-v01,legacy-v02,legacy-v03
-- -D warnings
- make -B -C lib libzstd.a ZSTD_LEGACY_SUPPORT=3 V=1
- git diff --cached --check
Move the reusable buffer and compression-context pools behind a Rust
implementation with a narrow C ABI adapter. The scheduler, job table, serial
LDM state, and stream orchestration remain in C until their private layouts
are ported.
Keep context types opaque across Rust modules so the pool bridge does not
depend on private C layout declarations. This also keeps the existing custom
allocator and pool replacement contracts intact.
Test Plan:
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo clippy --manifest-path
rust/Cargo.toml --all-targets -- -D warnings
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo test --manifest-path
rust/Cargo.toml zstdmt_compress
- make -B -C lib lib-mt
- git diff --cached --check
Move COVER training, frequency mapping, segment selection, optimization,
dictionary shrinking, and best-candidate synchronization into Rust. The
remaining C translation unit is an ABI shim, while the public ZDICT and COVER
symbols stay available to the existing C dictionary-builder callers.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml dict_builder_cover
- cargo check --manifest-path rust/Cargo.toml --no-default-features --features compression,decompression,dict-builder
- cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
- make -B -C lib libzstd.a V=1
- git diff --check
Depends-on: Rust compression, entropy, and dictionary-finalization leaves
Move the public ZBUFF compatibility layer into the Rust static archive while
keeping stream contexts opaque and forwarding to the current ZSTD streaming
APIs. The deprecated C translation units are now declaration-only shims, so
the compatibility symbols work in compression-only and decompression-only
feature builds without duplicating private context layouts.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml
- cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
- cargo +nightly fmt --manifest-path rust/Cargo.toml -- --check
- make -B -C lib libzstd.a ZSTD_LIB_DEPRECATED=1 V=1
- C ZBUFF compress/decompress smoke test against the rebuilt static archive
Depends-on: Rust compression and decompression streaming ABI ports
Move the binary-tree optimal and ultra block parsers into Rust with a narrow
C projection of match-state, sequence-store, and entropy-table fields. Keep
the established C entry points as wrappers, and avoid reading uninitialized
entropy costs during dictionary tree updates.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml
- cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
- cargo +nightly fmt --manifest-path rust/Cargo.toml --all -- --check
- make -B -C tests test-zstream V=1
- git diff --check
Refs: rust/src/zstd_opt.rs, lib/compress/zstd_opt.c
Translate the frozen v0.2 frame, entropy, block, frame-size, and streaming
decoder paths to Rust while preserving the opaque C context ABI. Replace the
3465-line historical C implementation with a declaration-only shim and enable
the Rust module for the legacy-v02 Cargo feature.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression,decompression,dict-builder,legacy-v02
- make -B -C lib libzstd.a ZSTD_LEGACY_SUPPORT=2 V=1
- git diff --check
Refs: rust/src/legacy/zstd_v02.rs, lib/legacy/zstd_v02.c
Implement ZSTD_compress in Rust using the migrated parameter, match-finder,
sequence, frame, and superblock leaves. Keep the private context and streaming
entry points C-backed until their configuration-dependent context projection is
ported, and remove only the duplicate C one-shot definition.
Test Plan:
- cargo test --manifest-path rust/Cargo.toml
- cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
- cargo +nightly fmt --manifest-path rust/Cargo.toml --all -- --check
- make -B -C tests test-rust-lib-smoke V=1
- git diff --check
Refs: rust/src/zstd_compress.rs, lib/compress/zstd_compress.c
Continue the incremental zstd_compress.c migration with its sequence
statistics and seqStore entropy-compression layer. The following now
live in rust/src/zstd_compress_stats.rs:
- ZSTD_seqToCodes(), exported under its original name because the C
dictionary builder (zdict.c) and decodecorpus link against it,
- ZSTD_buildSequencesStatistics() and its dummy variant, whose result
struct no longer crosses the language boundary,
- ZSTD_entropyCompressSeqStore_internal(), _wExtLitBuffer(), and
ZSTD_entropyCompressSeqStore(),
- ZSTD_buildBlockEntropyStats() with its literals/sequences helpers,
- ZSTD_copyBlockSequences() and the ZSTD_updateRep() rules it shares
with the superblock writer.
Boundary: ZSTD_CCtx and ZSTD_CCtx_params stay private to C. These
paths read exactly two parameter fields, so the C shims keep the
original static/exported function names and forward the strategy and
ZSTD_literalsCompressionIsDisabled() as int scalars alongside the
seqStore and entropy-table leaves. The leaf layouts (SeqDef,
SeqStore_t, ZSTD_hufCTables_t, ZSTD_fseCTables_t, entropy metadata,
SeqCollector, ZSTD_Sequence) are pinned by compile-time asserts in
zstd_compress.c and by both-pointer-width layout tests in Rust.
ZSTD_buildSeqStore, block dispatch/splitting, and the block-size
estimation helpers remain C for a later slice.
The superblock module previously round-tripped through the C export of
ZSTD_buildBlockEntropyStats and mirrored the entropy leaf structs
privately. It now calls the crate-internal builder directly, and the
shared struct definitions moved to zstd_compress_stats; consequently
ZSTD_rust_compressSuperBlock() takes the two parameter scalars instead
of an opaque ZSTD_CCtx_params pointer, extracted by its C shim. Its
layout and repcode tests moved with the definitions.
One C helper family gets no shim: the static
ZSTD_entropyCompressSeqStore_wExtLitBuffer() had a single caller and
was folded into the Rust implementation.
Byte-identity was verified against the pre-change compressor: COPYING,
datagen -g5000000 -s7, and datagen -g300000 -s21 -P90, each at levels
1/3/9/19 and --fast=5, plus a superblock-heavy pass at level 19 with
--target-compressed-block-size=1024; all 18 frames are byte-identical,
covering the repeat-mode state machine, longOffsets, RLE/raw fallback,
and dstSize_tooSmall paths through the block splitter and superblock.
Test plan:
- cd rust && cargo fmt --check && cargo clippy --all-targets -- -D
warnings && cargo test --all-targets (131 tests: new reference
vectors for seqToCodes, RLE table headers, empty-seqStore repeat
copies, literal-stats type selection, and repcode resolution in
copyBlockSequences)
- cargo build --release --no-default-features --features compression
and --features decompression
- make -C tests fuzzer && ./tests/fuzzer -i1 --no-big-tests (covers
ZSTD_generateSequences and ZDICT training over the Rust seqToCodes)
- make -C tests test-rust-lib-smoke
- ./tests/zstreamtest -i1 and ./tests/zstreamtest --newapi -t1 -i1
- ./tests/decodecorpus -t -T1s (decodecorpus links Rust seqToCodes)
- /tmp/ref vs /tmp/got frame diff as described above: byte-identical
Port lib/legacy/zstd_v01.c (the frozen zstd v0.1 decoder) to
rust/src/legacy/zstd_v01.rs as the first legacy-format port on the new
scaffolding, and reduce the C file to a declaration-only shim that
keeps its header includes for configuration and platform preprocessor
behavior.
Frozen-decoder policy: zstd_v01.c embeds its own v0.1-era FSE and
Huff0 snapshot, distinct from every other release. The Rust port is a
line-by-line translation with the same table layouts (FSE_DTable as a
u32 header word plus packed newState/symbol/nbBits entries, the Huff0
u16 DTable with byte/nbBits pairs), the same arithmetic including
wrap-around and pointer-comparison quirks (e.g. the offset-vs-base
address check in ZSTD_execSequence), the same internal FSE error space
(size_t)-1..-7, and the same public ZSTD error codes. It reuses no
modern Rust entropy module; its only crate dependency is `errors`,
matching the C file's error_private.h include. The 32-bit-only reload
points are kept as compile-time conditions on usize::BITS.
Symbol takeover boundary: all nine ZSTDv01_* entry points from
zstd_v01.h now come from Rust as context-free #[no_mangle] extern "C"
functions (isError, decompress, decompressDCtx,
findFrameSizeInfoLegacy, createDCtx, freeDCtx, resetDCtx,
nextSrcSizeToDecompress, decompressContinue). zstd_legacy.h only uses
the first four for v0.1; streaming for v0.1-v0.3 intentionally returns
version_unsupported there, unchanged. The ZSTDv01_Dctx struct
definition moves entirely into Rust: C code only ever holds an opaque
pointer (zstd_v01.h forward-declares the type), and the context is
malloc/free-allocated exactly like the C version so create/free may
pair across the language boundary.
Byte-identity verification against the pristine pre-migration C build
(f8745da6, pure C, ZSTD_LEGACY_SUPPORT=1):
- Real v0.1 frames were generated by building the v0.1.0 git tag and
compressing text, random, and 426 KB multi-block inputs. A one-shot
ZSTD_decompress harness linked once against the pristine C libzstd.a
and once against the Rust-backed libzstd.a produced bit-identical
outputs for all frames.
- A direct ZSTDv01_* probe (one-shot decode, dst-too-small, truncated
input, bad magic, findFrameSizeInfoLegacy, and the streaming
continue loop) printed identical results, including exact error
codes (-70 dstSize_tooSmall, -72 srcSize_wrong, -10 prefix_unknown)
and identical dBound values.
- zstd -l -v on v0.1 files matches the pristine binary; CLI streaming
decode of v0.1 fails with the same "Version not supported" in both,
by design of zstd_legacy.h.
Unit tests embed three v0.1.0-generated fixtures (entropy-coded,
raw-block, and four-block frames) plus the truncation, bad-magic,
small-destination, and streaming-API cases, all asserting the exact C
error codes above. Note that `make -C tests test-legacy` only covers
v0.4+ frames, so the embedded fixtures and the harness comparison are
the actual v0.1 coverage.
Test plan:
- cd rust && cargo fmt --check && cargo clippy --all-targets
--features legacy-v01 -- -D warnings && cargo test --all-targets
--features legacy-v01 (127 tests, 9 for v0.1)
- cargo clippy/test --no-default-features --features
decompression,legacy-v01 (module builds standalone)
- make -C tests fuzzer && ./tests/fuzzer -i1 --no-big-tests, also with
ZSTD_LEGACY_SUPPORT=1 (mixed Rust v0.1 + C v0.2-0.7 link)
- make -C tests test-rust-lib-smoke && make -C tests test-legacy
- make -C programs zstd (default and ZSTD_LEGACY_SUPPORT=1); nm shows
the nine ZSTDv01_* symbols provided by Rust at level 1
- make -C lib libzstd.a ZSTD_LEGACY_SUPPORT=0 (no legacy symbols) and
meson -Dlegacy_level=1 shared library exporting all nine
The legacy decoders (lib/legacy/zstd_v01.c .. zstd_v07.c) are next in
the Rust migration. Each of those files is a frozen snapshot of the
FSE/Huff0 entropy coders and frame logic of one historical release, so
their ports must not reuse the modern Rust entropy modules and must not
share code with each other: outputs and error codes have to stay
byte-identical to the frozen C forever. This commit installs the
build-system scaffolding so seven per-version ports can land
independently, each adding only its own module file plus a one-line
registration in rust/src/legacy/mod.rs.
Cargo grows features legacy-v01 .. legacy-v07. They are never default
features: the C build defaults differ per build system, so each build
system passes the list explicitly, derived from its own legacy
configuration:
- lib/Makefile and programs/Makefile map ZSTD_LEGACY_SUPPORT=N to the
features for versions N..7 (0 disables legacy), mirroring the
ZSTD_LEGACY_FILES selection in lib/libzstd.mk.
- tests/Makefile always enables all seven features because its
ZSTDLEGACY_FILES wildcard compiles every lib/legacy/*.c regardless of
the dispatch level.
- build/meson maps legacy_level exactly like the makefiles; build/cmake
enables all seven whenever ZSTD_LEGACY_SUPPORT is ON because it
always compiles all seven C files (ZSTD_LEGACY_LEVEL only selects the
C dispatch).
Every build system also encodes the legacy selection in the Rust target
directory name (e.g. c1-d1-default-legacy5), for the same reason the
HUF mode is encoded there: a cached archive built for one configuration
must never be linked into a build expecting another. In tests/Makefile
the legacy level additionally flows into the existing HUF C-mode stamp,
so the flat C test objects (which bake -DZSTD_LEGACY_SUPPORT into the
dispatch) are rebuilt whenever the level changes. In programs/Makefile
the compress-only, decompress-only, and CLI archives keep
level-independent directories (RUST_HUF_MODE) because they are only
linked into ZSTD_LEGACY_SUPPORT=0 program variants and carry no legacy
features.
A feature whose version has not been ported yet gates nothing: the
module registration in rust/src/legacy/mod.rs is added by each port,
so enabling e.g. legacy-v05 today simply leaves that decoder in C.
This is what makes mixed C/Rust legacy levels link cleanly while the
seven ports land in any order.
Test plan:
- cd rust && cargo fmt --check && cargo clippy --all-targets
-- -D warnings && cargo test --all-targets
- cargo clippy with --no-default-features --features
decompression,legacy-v01 and with all seven legacy features
- make -C tests fuzzer && ./tests/fuzzer -i1 --no-big-tests
- make -C tests test-rust-lib-smoke; make -C tests test-legacy
- make -C lib libzstd.a with ZSTD_LEGACY_SUPPORT=0, 1 and default (5)
- cmake configure and meson setup (including -Dlegacy_level=1) emit the
expected --features lists and legacy-suffixed target directories
Move the dictionary builder's suffix-array construction from
lib/dictBuilder/divsufsort.c to rust/src/divsufsort.rs, the first
dictBuilder module to migrate. It rides on the dict-builder cargo
feature dimension introduced by the previous commit.
divsufsort() is a self-contained algorithm (two-stage sort of type-B*
substrings via sssort, rank refinement via trsort, then induced sorting
of the full array), so its context-free signature allows a direct symbol
takeover: the Rust #[no_mangle] export provides the existing `divsufsort`
symbol and the C file becomes a declaration-only shim that just keeps the
header's prototypes in the build. Only divsufsort() moved; divbwt() has
no callers anywhere in zstd, so it is now declaration-only, keeping the
Rust export surface minimal. The unused openMP parameter is retained for
signature compatibility (zstd never defines LIBBSC_OPENMP).
The port is a mechanical translation of the exact configuration zstd
compiles: ALPHABET_SIZE=256, SS_INSERTIONSORT_THRESHOLD=8,
SS_BLOCKSIZE=1024, SS_MISORT_STACKSIZE=16, SS_SMERGE_STACKSIZE=32,
TR_STACKSIZE=64. Every C `int*` cursor into the SA buffer becomes an
`isize` index into a single `&mut [i32]` slice, preserving the pointer
arithmetic (including transient one-before-the-range cursors and the
bitwise-complement rank marking) while staying bounds-checked; all value
arithmetic keeps C int semantics. The C -1/-2 error results are
preserved, with Vec::try_reserve_exact standing in for the bucket-array
malloc failure path. Behavior is bit-identical by construction and by
measurement (see test plan); runtime on an 11 MB training buffer is
within ~5% of the C build end-to-end.
Users see no behavioral change: dictionaries trained through
ZDICT_trainFromBuffer_legacy() are byte-identical to the C build. The
only external difference is that the never-called `divbwt` symbol is no
longer defined in the library.
Test plan:
- cd rust && cargo fmt --check && cargo clippy --all-targets
-- -D warnings && cargo test --all-targets && cargo build --release
(125 tests pass; new unit tests cover empty/one/two-byte inputs,
all-equal bytes, an exact hand-computed "abracadabra" SA, and
fixed-seed LCG buffers at 256-, 4-, and 2-symbol alphabets verified
against a naive reference sort plus permutation/sorted invariants)
- Feature matrix: cargo build --release --no-default-features
--features compression,decompression (and decompression-only,
compression-only, compression,dict-builder); `divsufsort` is exported
only when dict-builder is enabled
- make -C tests fuzzer && ./tests/fuzzer -i1 --no-big-tests (includes
ZDICT training tests): pass
- make -C tests test-rust-lib-smoke: pass
- make -C tests test-invalidDictionaries: pass
- make -C programs zstd zstd-dictBuilder zstd-small zstd-compress
zstd-decompress: build; compress/decompress round-trip verified
- Byte-identity vs pristine C build (commit 959e4852): a harness calling
ZDICT_trainFromBuffer_legacy() (the only zstd path reaching
divsufsort) and divsufsort() directly, linked against both libzstd.a
builds, produces byte-identical dictionaries (80,288 B and full
112,640 B capacity) and byte-identical suffix arrays on a 1 MB source
set and an 11 MB binary/repetitive set; a differential driver over 148
random and structured buffers (sizes 3..6000, alphabets 1..256,
Fibonacci word, sawtooth, 6 KB near-constant) shows zero mismatches.
The CLI --train path could not be exercised because the Rust CLI
frontend rejects --train in both the pristine and ported builds (a
pre-existing migration gap unrelated to this change).
The dictionary-builder sources (lib/dictBuilder) are about to start moving
to Rust, beginning with divsufsort. The Rust crate previously only modeled
the compression/decompression module split plus the forced-HUF decoder
modes, so no build could express "this C configuration includes (or
excludes) dictBuilder" to Cargo. Without that, a Rust archive could carry
dictBuilder modules into a build whose C side disabled them, or worse,
omit a migrated implementation from a build whose C shims require it.
Add a `dict-builder` cargo feature and thread it through every build that
consumes the Rust static archive, mirroring exactly how each build system
already gates the dictBuilder C sources:
- rust/Cargo.toml: new `dict-builder` feature, included in the default
set because the C library builds dictBuilder by default
(ZSTD_LIB_DICTBUILDER ?= 1). The feature is empty until the first
dictBuilder module lands.
- lib/Makefile: RUST_CARGO_FEATURES gains dict-builder when
ZSTD_LIB_DICTBUILDER is enabled, following the existing
ZSTD_LIB_COMPRESSION/ZSTD_LIB_DECOMPRESSION pattern. The archive
directory naming grows a matching `b<0|1>` dimension
(c1-d1-b1-default etc.) so differently configured archives never
collide; the repeated config prefix is factored into
RUST_MODULE_CONFIG.
- programs/Makefile: the full-featured archives now request
compression,decompression,dict-builder (equal to the default set, so
the target directory stays shared with tests). The partial-library
variants gain the `b0` name dimension, and zstd-dictBuilder gets its
own lib-c1-d0-b1 archive because it compiles the dictBuilder C sources
without decompression; it previously shared the compression-only
archive, which will lack the migrated dictBuilder symbols.
- tests/Makefile: no flag change needed since tests use the crate default
feature set; a comment now records that dict-builder arrives that way.
- build/cmake/lib/CMakeLists.txt: ZSTD_BUILD_DICTBUILDER now adds the
dict-builder feature and a `b<0|1>` component in the Rust build-config
directory name, in lockstep with the DictBuilderSources gating.
- build/meson/lib/meson.build: meson compiles the dictBuilder sources
unconditionally, so the feature list and config name gain dict-builder
unconditionally (c1-d1-b1-<huf-mode>).
The `dict-builder` feature deliberately does not imply `compression`.
lib/Makefile forces ZSTD_LIB_DICTBUILDER=0 when compression is disabled,
but CMake does not couple the two options, so encoding the C-side
constraint in Cargo would make the Rust archive diverge from the C source
list in that (already unsupported) CMake configuration.
Test plan:
- cd rust && cargo build --release
- cargo build --release --no-default-features \
--features compression,decompression
- cargo build --release --no-default-features \
--features compression,dict-builder
- Full validation (fuzzer, smoke tests, dictionary byte-identity) runs
with the follow-up commit that ports divsufsort onto this scaffolding.
Move the context-free compression-parameter logic of zstd_compress.c to
rust/src/zstd_compress_params.rs: the compression-level tables (formerly
clevels.h), parameter bounds/checking/clamping, cycle log, level-table
selection, source/dictionary parameter adjustment, default frame
parameters, and the match-state/CDict size estimators.
The boundary follows the module's design notes: Rust owns only leaves
whose behavior is independent of C preprocessor configuration. C keeps
the public ZSTD_* symbols and feeds the leaves everything that is
configuration-owned as explicit scalars:
- The ZSTD_EXCLUDE_*_BLOCK_COMPRESSOR strategy cascade stays in
ZSTD_adjustCParams_internal() ahead of the Rust adjustment leaf, so
reduced builds keep their fallback policy.
- Workspace estimation receives struct sizes (ZSTD_CDict, ZSTD_match_t,
ZSTD_optimal_t), HUF workspace size, and the sanitizer redzone size,
because those depend on private layouts and ASAN configuration.
- ZSTD_cParam_getBounds() forwards only the compression level and the
seven core parameters; all other parameter bounds remain C.
- Frozen private constants the leaves hardcode (short-cache and row-hash
tag widths, MaxML/MaxLL/MaxOff/Litbits, ZSTD_OPT_SIZE, cwksp alignment)
are pinned by ZSTD_STATIC_ASSERTs at the C call sites.
Two latent 32-bit bugs in the previously unwired module were fixed
before integration: dictAndWindowLog's max window size and the
window-resize threshold were hardcoded to the 64-bit constants
(1<<31, 1<<30) instead of deriving from ZSTD_WINDOWLOG_MAX, which is
30 on 32-bit targets.
clevels.h is no longer included anywhere but stays in-tree as the
reference for mechanical comparison against the Rust table.
Test plan:
- cd rust && cargo fmt --check && cargo clippy --all-targets -- -D
warnings && cargo test --all-targets (125 tests)
- make -C tests fuzzer && ./tests/fuzzer -i1 --no-big-tests
- make -C tests test-rust-lib-smoke
- Byte-identity: zstd CLI frames for COPYING, a 250 KB C source, and a
5 MB datagen sample at levels 1/3/9/19/--fast=5 are identical between
this change and its parent commit.
Continue the incremental zstd_compress.c migration with its frame
serialization leaves: ZSTD_writeFrameHeader(), the public
ZSTD_writeSkippableFrame() ABI, and ZSTD_writeLastEmptyBlock() now live
in rust/src/zstd_compress_frame.rs.
ZSTD_writeFrameHeader() reads five fields out of ZSTD_CCtx_params, whose
layout is private to zstd_compress.c and sensitive to build
configuration. Rather than mirror that structure in Rust, the C
function keeps its original static signature and forwards the scalar
fields to ZSTD_rust_writeFrameHeader(), so no parameter-structure layout
crosses the language boundary. The other two functions take only
pointer/size arguments and are exported directly, replacing their C
bodies outright.
Behavior differences are limited to hardening in release builds: the
Rust leaf clamps a window-size shift that C would leave undefined for a
malformed windowLog, and ZSTD_writeSkippableFrame() rejects a srcSize +
header overflow instead of comparing against a wrapped sum. Both paths
are unreachable through validated callers, so compressed output is
byte-identical.
Remaining zstd_compress.c work: parameter selection and validation,
context lifecycle, block dispatch, dictionary loading, and the streaming
state machine.
Test plan:
- cd rust && cargo fmt --check && cargo clippy --all-targets -- -D
warnings && cargo test --all-targets (118 tests, includes new frame
header/skippable/last-block reference vectors)
- make -C tests fuzzer && ./tests/fuzzer -i1 --no-big-tests
- make -C tests test-rust-lib-smoke
Move long-distance matching and high-level decompression from C shims into
Rust. The decoder now owns context, dictionary, parameter, one-shot, and
buffered streaming state while C retains allocation/configuration, legacy,
and trace leaves.
Move CLI parsing, safety policy, and dispatch into a separate Rust static
archive. Keeping it separate prevents library builds from retaining FIO
symbols, while C continues to own file opening, replacement, and I/O.
Program targets now select matching compression/decompression archives.
The remaining C boundary is intentional: high-level compression, optimal
parsing, dictionary building, legacy callbacks, and CLI file I/O still need
migration.
Test Plan:
- cargo test --all-targets (native and i686)
- cargo test --all-targets in rust/cli (native and i686)
- CLI crate compression-only and decompression-only feature tests
- native and i686 fuzzer/zstreamtest runs, plus legacy and dictionary tests
- ZSTD_C_PREDICT and ZSTD_HEAPMODE=0 fuzzer coverage
- library, dynamic-link, and program-target build/round-trip matrix
Refs: rust/README.md
Move the binary-tree table maintenance shared by optimal compression strategies
into Rust. A small C projection preserves the private match-state boundary;
the dynamic-programming parser and match selection remain C-owned for now.
The Rust implementation covers prefix and external-dictionary tree updates and
preserves the optional C predictor path. The component map now distinguishes
this migrated tree layer from the remaining optimal parser.
Test Plan:
- cargo test --all-targets
- cargo test --target i686-unknown-linux-gnu --all-targets
- cargo clippy && cargo clippy --benches && cargo clippy --tests
- cargo +nightly fmt
- make -B -C tests -j2 fuzzer zstreamtest invalidDictionaries
- ./tests/fuzzer -s5346 -i1 --no-big-tests
- ./tests/zstreamtest -i3000 -s334462
- ./tests/invalidDictionaries
- make -B -C tests fuzzer32 MOREFLAGS=-DZSTD_C_PREDICT
- ./tests/fuzzer32 -s5346 -i1 --no-big-tests
- byte-compare C and Rust-control CLI output at levels 13, 16, 19, and 22
for random, patterned, zero, and dictionary inputs with and without
ZSTD_C_PREDICT
Refs: rust/README.md
Move literal decoding, sequence-table construction, FSE sequence decoding, and
sequence execution into Rust. The C shim retains ownership of the configured
decoder context and passes only the leaf state needed by the block codec.
Correct the two high offset-code bases while porting the tables. Their prior
values made valid large-window streams decode as corrupted data; the new unit
test fixes the exact values and a native zstream regression exercises them.
High-level frame and streaming context control remains C for now.
Test Plan:
- cargo test --all-targets
- cargo test --target i686-unknown-linux-gnu --all-targets
- cargo clippy && cargo clippy --benches && cargo clippy --tests
- cargo +nightly fmt
- make -B -C tests -j2 fuzzer zstreamtest invalidDictionaries poolTests
- ./tests/fuzzer -s5346 -i1 --no-big-tests
- ./tests/zstreamtest -i3000 -s334462
- ./tests/invalidDictionaries
- timeout 20s stdbuf -oL ./tests/poolTests
Refs: rust/README.md
Move the two-table fast match finder into Rust while retaining a small C
projection of the private match-state. The Rust implementation handles normal,
attached-dictionary, and external-dictionary matching without exposing the
full C context ABI. The C entry points and build-time exclusion guards remain
unchanged for configured consumers.
Document the migrated matcher in the Rust component map and narrow the
remaining-C boundary accordingly.
Test Plan:
- cargo test --all-targets
- cargo test --target i686-unknown-linux-gnu --all-targets
- cargo clippy && cargo clippy --benches && cargo clippy --tests
- cargo +nightly fmt
- make -B -C tests -j2 fuzzer zstreamtest invalidDictionaries poolTests
- ./tests/fuzzer -s5346 -i1 --no-big-tests
- ./tests/zstreamtest -i3000 -s334462
- ./tests/invalidDictionaries
- timeout 20s stdbuf -oL ./tests/poolTests
Refs: rust/README.md
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