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
Link poolTests against the multithreaded object set and Rust static archive,
so its C callbacks exercise the migrated pool rather than compiling a private
C implementation. Preserve ZSTD_MULTITHREAD for the test translation unit;
without it, its pthread test helpers become no-ops while the Rust pool runs
concurrently. Add a Rust regression for draining a small queue after reducing
the worker limit.
Test Plan:
- cargo clippy
- cargo clippy --benches
- cargo clippy --tests
- cargo +nightly fmt
- cargo test shrinking_the_limit_keeps_draining_a_small_queue -- --nocapture
- make -B -C tests poolTests && timeout 20s stdbuf -oL ./tests/poolTests
Refs: Rust pool migration 26b5e202
The fuzz Makefile compiles libzstd sources directly, so C compatibility shims
previously left migrated symbols unresolved. Build and link a configuration
matched Cargo archive after the C objects for every fuzz target.
Track forced HUF mode changes with a C-object stamp to prevent a stale C
decoder from being mixed with another Rust archive. A -m32 invocation now
also selects Cargo's i686 target rather than attempting to link native Rust
objects into a 32-bit fuzzer.
Test Plan:
- build and run huf_round_trip and dictionary_round_trip on LICENSE
- transition default to forced X1 and back without cleaning, then run input
- build and run huf_round_trip with C/C++/linker -m32 flags
- cargo clippy, cargo clippy --benches, cargo clippy --tests, and nightly fmt
Refs: tests/fuzz/Makefile Rust archive configuration
Build feature-matched Rust archives for the native Make library path. Flatten
their members into libzstd.a so static consumers resolve C-to-Rust and
Rust-to-C references in one archive, and whole-archive link shared outputs so
every migrated public ABI export remains available.
Rust compression and decompression features now mirror the C partial-library
switches. This prevents compression-only artifacts from retaining DDict
references to decompression-only C helpers.
Add a C archive smoke test that round-trips data and exercises the DDict
lifecycle through lib/libzstd.a, rather than direct test-object links.
Test Plan:
- cargo fmt, strict Clippy, cargo test --all-targets, release build
- Rust checks with compression-only, decompression-only, and no features
- full, partial, forced-HUF, and 32-bit static/shared Make library probes
- test-rust-lib-smoke, fuzzer, zstreamtest, and invalidDictionaries
Refs: rust/README.md
Mode-specific Rust archives exposed the test makefiles' flat C-object cache:
switching from default to forced HUF mode could relink stale default C objects
with a newly built forced Rust archive. That hybrid has incompatible decoder
table expectations and can corrupt dictionary decompression.
Track each makefile's effective HUF mode with an empty archive stamp. It is a
safe normal linker prerequisite, and every mode transition advances its mtime
so cached C objects and direct-source binaries rebuild while unchanged modes
remain incremental.
Test Plan:
- cargo clippy; cargo clippy --benches; cargo clippy --tests
- cargo +nightly fmt, then repeat the Clippy checks
- cargo test --all-targets
- Default -> forced-X1 -> default fuzzer builds without -B, each running
./fuzzer -s5346 -i1 --no-big-tests
- Equivalent zstd-small default/forced/default rebuild and --version checks
Refs: rust/README.md
Fixes: d89ebb31
Derive the Rust static-library configuration from the effective C HUF decoder
flags and place each mode in its own Cargo target directory. This prevents a
forced X1/X2 C build from silently reusing the default Rust archive.
The test and program makefiles now also build and link an i686 Rust archive
for their 32-bit targets, including zstd32. zstd-small retains its existing
default configuration while preserving an explicitly requested HUF mode.
Test Plan:
- cargo clippy; cargo clippy --benches; cargo clippy --tests
- cargo +nightly fmt, then repeat the Clippy checks
- cargo test --all-targets for default, forced X1, and forced X2 modes
- cargo build --release --target i686-unknown-linux-gnu for each mode
- make -n checks for default, forced, direct -D, and 32-bit test/CLI targets
Refs: rust/README.md
Make Rust sources normal prerequisites of native C test executables and CLI
builds. A changed Rust module now rebuilds libzstd_rs.a and relinks the target,
instead of relying on a manually prepared archive that can silently be stale.
The archive is linked after C objects, allowing migrated C shims to resolve
their Rust ABI symbols while remaining compatible with the existing makefile
flows. The migration guide now documents this behavior.
Test Plan:
- make -B -C tests fuzzer
- ./tests/fuzzer -i1 --no-big-tests
- make -B -C programs zstd
- ./programs/zstd --version
Refs: rust/README.md
Introduce the Rust static library and move the shared byte, bitstream, CPU,
error, xxHash, debug, and public-common implementations into it. Thin C shims
preserve the existing header-driven C build while original tests link the Rust
archive.
This establishes the ABI-safe foundation for later codec and CLI ports;
entropy coding, runtime support, codecs, dictionaries, and the CLI remain C.
The top-down migration map documents that boundary and its validation path.
Test Plan:
- cargo fmt --check
- cargo test --all-targets
- cargo clippy --all-targets -- -D warnings
- cargo build --release
Refs: rust/README.md
so that a human reading the test log can determine everything was fine without consulting the shell error code.
Also: made `make check` slightly shorter by moving one longer test to `make test`
which creates more "realistic" scenarios than former compressible noise.
The legacy data generator remains accessible,
it is triggered when requesting an explicit compressibility factor (-P#).
ddidderr
