mikronova/openzl-sys-rs

Vendored C sources

Everything under this directory is third-party C source, copied verbatim from upstream release artifacts. Nothing here is modified. build.rs compiles it with the cc crate — there is no network access, no curl, no tar, no git, no cmake and no process spawned at build time.

Provenance

The two dependency hashes are the ones OpenZL itself pins in build-scripts/cmake/openzl-deps.cmake (ZSTD_TARBALL_SHA256 line 27, LZ4_TARBALL_SHA256 line 114), so the vendored zstd and lz4 are exactly what OpenZL's own CMake would have downloaded. v0.3.0 pins the same zstd 1.5.7 and lz4 1.10.0 as the previous vendored commit, so deps/ is unchanged. The OpenZL hash is the GitHub tag tarball, downloaded 2026-10-02; src/, include/, LICENSE and CHANGELOG were replaced from it and checked byte-identical.

Which OpenZL each wrapper line bundles

The wrapper's version number is not OpenZL's. From 0.4.0 the crate version carries the bundled OpenZL release as build metadata (0.4.0+openzl.0.3.0).

OpenZL 0.3.0 writes frame format 27 by default (ZL_getDefaultEncodingVersion). A reader built on any 0.1–0.3 wrapper decodes at most format 25, so a writer that must stay readable by them sets ZL_CParam_formatVersion explicitly.

Regenerating src/bindings.rs

The bindings are pre-generated so the crate needs no libclang. 0.4.0's were produced with bindgen-cli 0.73.2 against libclang 21, from the crate root:

bindgen wrapper.h --allowlist-function 'ZL_.*' --allowlist-type 'ZL_.*' \
    --allowlist-var 'ZL_.*' -o src/bindings.rs -- -I openzl/include -I openzl/src

(the same allowlist the 0.1.0 build-time bindgen used). API changes against the 0.3.x bindings: ZL_MaterializerDesc2 is now ZL_MaterializerDesc, ZL_Compressor_registerBruteForceSelectorGraph is replaced by ZL_Compressor_buildBruteForceSelectorGraph, and new functions/types appear (ZL_Compressor_buildTrainableZstdGraph, ZL_Graph_getMParam, ZL_Graph_getLocalParams, ZL_Edge_setEntropyDestination, ZL_E_clearInfo, ZL_OperationContext_ownsError, ZL_LzParam, ZL_LzStrategy, ZL_Result_uint{16,32,64}_t). The crate's own helpers (ZlCCtx, ZlDCtx, zl_compress_bound, zl_decompress, zl_get_decompressed_size) wrap none of the renamed items and are unchanged; ZL_COMPRESSBOUND is identical in 0.3.0.

What was and was not copied

• src/, include/ — OpenZL, complete.
• deps/zstd/lib/{common,compress,decompress,dictBuilder} plus zstd.h, zstd_errors.h, zdict.h. lib/legacy is omitted: OpenZL builds zstd with -DZSTD_LEGACY_SUPPORT=0, so none of it is compiled.
• deps/lz4/lib/*.{c,h} — the library only. lz4's programs/ (which is GPL-2.0-or-later) is not vendored.

Licences

• OpenZL — BSD-3-Clause. openzl/LICENSE, Meta Platforms, Inc.
• zstd — dual-licensed BSD-3-Clause / GPL-2.0. The BSD-3-Clause option is elected here; openzl/deps/zstd/LICENSE is that text. Upstream's COPYING (the GPL-2.0 alternative, which is not elected) is not redistributed.
• lz4 — the vendored lib/ directory is BSD-2-Clause; openzl/deps/lz4/LICENSE is lz4's own lib/LICENSE. lz4's GPL-2.0-or-later programs/ tree is not vendored, so that licence does not apply to anything shipped here.

The crate's package license field is therefore BSD-3-Clause AND BSD-2-Clause.

Build configuration reproduced by build.rs

Ported from what CMake actually put on the compiler command line. Taken from a compile_commands.json of the 0.2.0 cmake build, not from reading the CMake by eye.

NDEBUG is defined when OPT_LEVEL != 0, matching CMake's Release configuration. Include order for openzl is: generated config dir, vendor root, include/, src/, deps/lz4/lib, deps/zstd/lib.

zl_config.h

Generated by build.rs into OUT_DIR/include/openzl/zl_config.h, reproducing configure_file(build-scripts/cmake/zl_config.h.cmake ...). Both knobs are 0:

• ZL_ALLOW_INTROSPECTION — 0.2.0 configured CMake with -DOPENZL_ALLOW_INTROSPECTION=OFF.
• ZL_HAVE_X86_64_ASM — 0 even on x86-64. Upstream's OpenZLConfigChecks.cmake sets a variable named OPENZL_HAVE_X86_64_ASM, while both zl_config.h.cmake and CMakeLists.txt test ZL_HAVE_X86_64_ASM, which nothing ever assigns. OpenZL's own huf_decompress_amd64.S was consequently never compiled by the 0.2.0 build either, and is not compiled here. This is upstream's bug, faithfully preserved so the library behaves identically; it is not something this crate should quietly "fix". v0.3.0 still has the same mismatch (OpenZLConfigChecks.cmake line 6/13 vs zl_config.h.cmake line 16).

System libraries

m and pthread on unix. 0.2.0 also emitted -lstdc++; it was never needed — the openzl target is built with OPENZL_BUILD_CPP=OFF and is pure C, and nm --undefined-only libopenzl.a reports zero C++ symbols. Dropping it removes libstdc++ from this crate's build requirements.

Escape hatch

Setting OPENZL_SYS_LIB_DIR to a directory containing libopenzl.a, libzstd.a and liblz4.a links those instead of compiling the vendored tree. The build script prints a line saying so, and fails loudly if any of the three is absent rather than half-linking.