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feat(decompress): move legacy dispatch into Rust

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Legacy detection, frame-size queries, one-shot decode, and buffered streaming
were still routed through the C header dispatcher even though every historical
v0.1 through v0.7 decoder is already ported under Rust feature gates.  The C
implementation also duplicated the support-level boundary independently from
the Rust archive selection.

Move the dispatcher and stream lifecycle to Rust using the existing DCtx field
projection.  Rust now selects the version, preserves the null-buffer and
position semantics, initializes and frees buffered legacy contexts, and calls
the frozen per-version modules.  C retains only the configuration leaf that
reports ZSTD_LEGACY_SUPPORT plus the private DCtx layout and trace helpers, so
library, program, and test builds can still choose different support levels.

Test Plan:
- `cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression,decompression,dict-builder,legacy-v01,legacy-v02,legacy-v03,legacy-v04,legacy-v05,legacy-v06,legacy-v07 --all-targets -- --test-threads=1` -- 528 passed.
- Native `test-legacy`, `test-invalidDictionaries`, `test-decodecorpus`, and `test-zstd` -- passed.
- Strict C syntax checks with legacy support 0, 4, 5, and 7 -- passed.
- `cargo clippy` default, benches, and tests for library and CLI -- passed.
This commit is contained in:
ddidderr
2026-07-18 22:41:17 +02:00
parent 0e0d87ddf5
commit 4304c0af40
2 changed files with 600 additions and 114 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/decompress/zstd_decompress.c
+9 -95
View File
@@ -16,10 +16,6 @@
#include "zstd_decompress_internal.h"
#include "zstd_ddict.h"
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
# include "../legacy/zstd_legacy.h"
#endif
/* Keep the three public build-time tuning knobs in the C configuration domain.
* Rust queries them through the small leaves below rather than baking a second
* set of defaults into its source. */
@@ -125,18 +121,7 @@ void ZSTD_rust_dctx_copy_prefix(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx);
void ZSTD_rust_dctx_trace_begin(ZSTD_DCtx* dctx);
void ZSTD_rust_dctx_trace_end(ZSTD_DCtx* dctx, U64 uncompressedSize,
U64 compressedSize, int streaming);
unsigned ZSTD_rust_legacy_is(const void* src, size_t srcSize);
unsigned long long ZSTD_rust_legacy_get_decompressed_size(const void* src,
size_t srcSize);
size_t ZSTD_rust_legacy_find_compressed_size(const void* src, size_t srcSize);
size_t ZSTD_rust_legacy_frame_size_info(const void* src, size_t srcSize,
size_t* compressedSize,
unsigned long long* decompressedBound,
size_t* nbBlocks);
size_t ZSTD_rust_legacy_decompress(void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
const void* dict, size_t dictSize);
void ZSTD_rust_legacy_free_stream(ZSTD_DCtx* dctx);
unsigned ZSTD_rust_legacy_support(void);
void ZSTD_rust_dctx_view(ZSTD_DCtx* dctx, ZSTD_rustDctxView* out)
{
@@ -319,87 +304,16 @@ void ZSTD_rust_dctx_trace_end(ZSTD_DCtx* dctx, U64 uncompressedSize,
#endif
}
unsigned ZSTD_rust_legacy_is(const void* src, size_t srcSize)
/* The Rust dispatcher has all version-specific legacy implementations. Keep
* the active C configuration as a leaf so test builds, which compile every
* Rust legacy module but vary this C macro per target, retain the historical
* support boundary. */
unsigned ZSTD_rust_legacy_support(void)
{
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
return ZSTD_isLegacy(src, srcSize);
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1) \
&& (ZSTD_LEGACY_SUPPORT <= 7)
return ZSTD_LEGACY_SUPPORT;
#else
(void)src;
(void)srcSize;
return 0;
#endif
}
unsigned long long ZSTD_rust_legacy_get_decompressed_size(const void* src, size_t srcSize)
{
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
return ZSTD_getDecompressedSize_legacy(src, srcSize);
#else
(void)src;
(void)srcSize;
return 0;
#endif
}
size_t ZSTD_rust_legacy_find_compressed_size(const void* src, size_t srcSize)
{
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
return ZSTD_findFrameCompressedSizeLegacy(src, srcSize);
#else
(void)src;
(void)srcSize;
return ERROR(prefix_unknown);
#endif
}
size_t ZSTD_rust_legacy_frame_size_info(const void* src, size_t srcSize,
size_t* compressedSize,
unsigned long long* decompressedBound,
size_t* nbBlocks)
{
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
ZSTD_frameSizeInfo const info = ZSTD_findFrameSizeInfoLegacy(src, srcSize);
*compressedSize = info.compressedSize;
*decompressedBound = info.decompressedBound;
*nbBlocks = info.decompressedBound == ZSTD_CONTENTSIZE_ERROR
? 0 : (size_t)(info.decompressedBound / ZSTD_BLOCKSIZE_MAX);
return ZSTD_isError(info.compressedSize) ? info.compressedSize : 0;
#else
(void)src;
(void)srcSize;
*compressedSize = ERROR(prefix_unknown);
*decompressedBound = ZSTD_CONTENTSIZE_ERROR;
*nbBlocks = 0;
return ERROR(prefix_unknown);
#endif
}
size_t ZSTD_rust_legacy_decompress(void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
const void* dict, size_t dictSize)
{
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
return ZSTD_decompressLegacy(dst, dstCapacity, src, srcSize, dict, dictSize);
#else
(void)dst;
(void)dstCapacity;
(void)src;
(void)srcSize;
(void)dict;
(void)dictSize;
return ERROR(prefix_unknown);
#endif
}
void ZSTD_rust_legacy_free_stream(ZSTD_DCtx* dctx)
{
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
if (dctx->legacyContext) {
ZSTD_freeLegacyStreamContext(dctx->legacyContext,
dctx->previousLegacyVersion);
dctx->legacyContext = NULL;
}
#else
(void)dctx;
#endif
}