9b909aaef8821d27e319363dcafb698e260e1b9e
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Commits
| Author | SHA1 | Message | Date | |
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 ddidderr
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9b909aaef8 |
feat(legacy): port the v0.2 decoder to Rust
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 |
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ddidderr
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322f99dfd0
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feat(rust): port legacy v0.1 decoder
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
(
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ddidderr
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bdd35c838d
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build(rust): add legacy feature scaffolding
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 |