zstd-rs/lib/decompress/zstd_decompress.c

/*
 * Decoder orchestration is implemented in rust/src/zstd_decompress.rs.
 *
 * `ZSTD_DCtx_s` is intentionally still allocated and laid out by C: its
 * optional members vary with the build configuration and the block decoder
 * shares that object.  This translation unit is therefore a deliberately
 * narrow ABI adapter.  It projects field addresses to Rust while retaining
 * the private layout and configuration-bound legacy leaves.  Weak trace-symbol
 * discovery also stays here; Rust receives only a narrow trace projection.
 */

#define ZSTD_STATIC_LINKING_ONLY
#include "../common/zstd_deps.h"
#include "../common/error_private.h"
#include "../common/mem.h"
#include "../common/zstd_internal.h"
#include "zstd_decompress_internal.h"
#include "zstd_ddict.h"

/* 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. */
#ifndef ZSTD_HEAPMODE
#  define ZSTD_HEAPMODE 1
#endif

#ifndef ZSTD_MAXWINDOWSIZE_DEFAULT
#  define ZSTD_MAXWINDOWSIZE_DEFAULT (((U32)1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT) + 1)
#endif

#ifndef ZSTD_NO_FORWARD_PROGRESS_MAX
#  define ZSTD_NO_FORWARD_PROGRESS_MAX 16
#endif

/* Keep this in lock-step with ZSTD_rustDctxView in zstd_decompress.rs.
 * Every pointer that names a scalar is the address of that scalar; array and
 * embedded-object entries name their first byte. */
typedef struct {
    void* dctx;
    void* llt_ptr;
    void* mlt_ptr;
    void* oft_ptr;
    void* huf_ptr;
    void* entropy;
    void* workspace;
    size_t workspace_size;
    void* previous_dst_end;
    void* prefix_start;
    void* virtual_start;
    void* dict_end;
    void* expected;
    void* f_params;
    void* processed_c_size;
    void* decoded_size;
    void* b_type;
    void* stage;
    void* lit_entropy;
    void* fse_entropy;
    void* xxh_state;
    void* header_size;
    void* format;
    void* force_ignore_checksum;
    void* validate_checksum;
    void* lit_ptr;
    void* custom_mem;
    void* lit_size;
    void* rle_size;
    void* static_size;
    void* is_frame_decompression;
    void* ddict_local;
    void* ddict;
    void* dict_id;
    void* ddict_is_cold;
    void* dict_uses;
    void* ddict_set;
    void* ref_multiple_ddicts;
    void* disable_huf_asm;
    void* max_block_size_param;
    void* stream_stage;
    void* in_buff;
    void* in_buff_size;
    void* in_pos;
    void* max_window_size;
    void* out_buff;
    void* out_buff_size;
    void* out_start;
    void* out_end;
    void* lh_size;
    void* legacy_context;
    void* previous_legacy_version;
    void* legacy_version;
    void* hostage_byte;
    void* no_forward_progress;
    void* out_buffer_mode;
    void* expected_out_buffer;
    void* lit_buffer;
    void* lit_buffer_end;
    void* lit_buffer_location;
    void* lit_extra_buffer;
    size_t lit_extra_buffer_size;
    void* header_buffer;
    size_t header_buffer_size;
    void* oversized_duration;
    void* fuzz_begin;
    void* fuzz_end;
    size_t dctx_size;
} ZSTD_rustDctxView;

typedef char ZSTD_rust_dctx_view_layout[
        (offsetof(ZSTD_rustDctxView, dctx) == 0
         && offsetof(ZSTD_rustDctxView, static_size) == 29 * sizeof(void*)
         && offsetof(ZSTD_rustDctxView, dctx_size) == 67 * sizeof(void*)
         && sizeof(ZSTD_rustDctxView) == 68 * sizeof(void*)) ? 1 : -1];

/* Rust exposes this as u64.  Use the trace API's exact unsigned-long-long
 * representation instead of U64, whose typedef may be a different C type on
 * some targets even when it has the same width. */
typedef unsigned long long ZSTD_rustTraceCtx;
typedef ZSTD_rustTraceCtx (*ZSTD_rustTraceBeginFn)(const void* dctx);
typedef void (*ZSTD_rustTraceEndFn)(ZSTD_rustTraceCtx traceCtx,
                                    const void* trace);

typedef struct {
    ZSTD_rustTraceCtx* trace_ctx;
    ZSTD_rustTraceBeginFn begin;
    ZSTD_rustTraceEndFn end;
    const void* dctx;
    const void* ddict;
    int dictionary_is_cold;
} ZSTD_rustDctxTraceView;

void ZSTD_rust_dctx_view(ZSTD_DCtx* dctx, ZSTD_rustDctxView* out);
void ZSTD_rust_dctx_trace_view(ZSTD_DCtx* dctx,
                               ZSTD_rustDctxTraceView* out);
size_t ZSTD_rust_dctx_sizeof(void);
void ZSTD_dctx_init_platform(ZSTD_DCtx* dctx);
void ZSTD_rust_dctx_init_platform(void* bmi2, int dynamic_bmi2);
size_t ZSTD_rust_dctx_default_max_window_size(void);
int ZSTD_rust_no_forward_progress_max(void);
size_t ZSTD_rust_decompress_stack(void* dst, size_t dstCapacity,
                                  const void* src, size_t srcSize);
size_t ZSTD_rust_decompress_stack_context(ZSTD_DCtx* dctx,
                                          void* dst, size_t dstCapacity,
                                          const void* src, size_t srcSize);

typedef struct {
    int heapmode;
    void* workspace;
    size_t workspace_size;
    void* dst;
    size_t dst_capacity;
    const void* src;
    size_t src_size;
} ZSTD_rustDecompressStackProjection;
typedef char ZSTD_rust_decompress_stack_projection_layout[
        (offsetof(ZSTD_rustDecompressStackProjection, heapmode) == 0
         && offsetof(ZSTD_rustDecompressStackProjection, workspace) == sizeof(void*)
         && offsetof(ZSTD_rustDecompressStackProjection, workspace_size)
                == 2 * sizeof(void*)
         && offsetof(ZSTD_rustDecompressStackProjection, dst)
                == 3 * sizeof(void*)
         && offsetof(ZSTD_rustDecompressStackProjection, dst_capacity)
                == 4 * sizeof(void*)
         && offsetof(ZSTD_rustDecompressStackProjection, src)
                == 5 * sizeof(void*)
         && offsetof(ZSTD_rustDecompressStackProjection, src_size)
                == 6 * sizeof(void*)
         && sizeof(ZSTD_rustDecompressStackProjection) == 7 * sizeof(void*))
        ? 1 : -1];

typedef ZSTD_DCtx* (*ZSTD_rustInitStaticDCtxFn)(void* workspace,
                                                 size_t workspace_size);
typedef size_t (*ZSTD_rustDecompressStackContextFn)(
        ZSTD_DCtx* dctx, void* dst, size_t dstCapacity,
        const void* src, size_t srcSize);
typedef struct {
    ZSTD_rustInitStaticDCtxFn init_static_dctx;
    ZSTD_rustDecompressStackContextFn decompress_context;
} ZSTD_rustDecompressStackCallbacks;
typedef char ZSTD_rust_decompress_stack_callbacks_layout[
        (offsetof(ZSTD_rustDecompressStackCallbacks, init_static_dctx) == 0
         && offsetof(ZSTD_rustDecompressStackCallbacks, decompress_context)
                == sizeof(void*)
         && sizeof(ZSTD_rustDecompressStackCallbacks) == 2 * sizeof(void*))
        ? 1 : -1];

size_t ZSTD_rust_decompress_stack_action(
        const ZSTD_rustDecompressStackProjection* projection,
        const ZSTD_rustDecompressStackCallbacks* callbacks);
unsigned ZSTD_rust_legacy_support(void);

#if ZSTD_TRACE
static ZSTD_rustTraceCtx ZSTD_rust_trace_begin_callback(const void* dctx)
{
    return (ZSTD_trace_decompress_begin != NULL)
        ? ZSTD_trace_decompress_begin((const ZSTD_DCtx*)dctx) : 0;
}

static void ZSTD_rust_trace_end_callback(ZSTD_rustTraceCtx traceCtx,
                                          const void* trace)
{
    if (ZSTD_trace_decompress_end != NULL) {
        ZSTD_trace_decompress_end((ZSTD_TraceCtx)traceCtx,
                                  (const ZSTD_Trace*)trace);
    }
}
#endif

void ZSTD_rust_dctx_view(ZSTD_DCtx* dctx, ZSTD_rustDctxView* out)
{
    ZSTD_memset(out, 0, sizeof(*out));
    if (dctx == NULL) return;

    out->dctx = dctx;
    out->llt_ptr = &dctx->LLTptr;
    out->mlt_ptr = &dctx->MLTptr;
    out->oft_ptr = &dctx->OFTptr;
    out->huf_ptr = &dctx->HUFptr;
    out->entropy = &dctx->entropy;
    out->workspace = dctx->workspace;
    out->workspace_size = sizeof(dctx->workspace);
    out->previous_dst_end = &dctx->previousDstEnd;
    out->prefix_start = &dctx->prefixStart;
    out->virtual_start = &dctx->virtualStart;
    out->dict_end = &dctx->dictEnd;
    out->expected = &dctx->expected;
    out->f_params = &dctx->fParams;
    out->processed_c_size = &dctx->processedCSize;
    out->decoded_size = &dctx->decodedSize;
    out->b_type = &dctx->bType;
    out->stage = &dctx->stage;
    out->lit_entropy = &dctx->litEntropy;
    out->fse_entropy = &dctx->fseEntropy;
    out->xxh_state = &dctx->xxhState;
    out->header_size = &dctx->headerSize;
    out->format = &dctx->format;
    out->force_ignore_checksum = &dctx->forceIgnoreChecksum;
    out->validate_checksum = &dctx->validateChecksum;
    out->lit_ptr = &dctx->litPtr;
    out->custom_mem = &dctx->customMem;
    out->lit_size = &dctx->litSize;
    out->rle_size = &dctx->rleSize;
    out->static_size = &dctx->staticSize;
    out->is_frame_decompression = &dctx->isFrameDecompression;
    out->ddict_local = &dctx->ddictLocal;
    out->ddict = &dctx->ddict;
    out->dict_id = &dctx->dictID;
    out->ddict_is_cold = &dctx->ddictIsCold;
    out->dict_uses = &dctx->dictUses;
    out->ddict_set = &dctx->ddictSet;
    out->ref_multiple_ddicts = &dctx->refMultipleDDicts;
    out->disable_huf_asm = &dctx->disableHufAsm;
    out->max_block_size_param = &dctx->maxBlockSizeParam;
    out->stream_stage = &dctx->streamStage;
    out->in_buff = &dctx->inBuff;
    out->in_buff_size = &dctx->inBuffSize;
    out->in_pos = &dctx->inPos;
    out->max_window_size = &dctx->maxWindowSize;
    out->out_buff = &dctx->outBuff;
    out->out_buff_size = &dctx->outBuffSize;
    out->out_start = &dctx->outStart;
    out->out_end = &dctx->outEnd;
    out->lh_size = &dctx->lhSize;
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
    out->legacy_context = &dctx->legacyContext;
    out->previous_legacy_version = &dctx->previousLegacyVersion;
    out->legacy_version = &dctx->legacyVersion;
#endif
    out->hostage_byte = &dctx->hostageByte;
    out->no_forward_progress = &dctx->noForwardProgress;
    out->out_buffer_mode = &dctx->outBufferMode;
    out->expected_out_buffer = &dctx->expectedOutBuffer;
    out->lit_buffer = &dctx->litBuffer;
    out->lit_buffer_end = &dctx->litBufferEnd;
    out->lit_buffer_location = &dctx->litBufferLocation;
    out->lit_extra_buffer = dctx->litExtraBuffer;
    out->lit_extra_buffer_size = sizeof(dctx->litExtraBuffer);
    out->header_buffer = dctx->headerBuffer;
    out->header_buffer_size = sizeof(dctx->headerBuffer);
    out->oversized_duration = &dctx->oversizedDuration;
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
    out->fuzz_begin = &dctx->dictContentBeginForFuzzing;
    out->fuzz_end = &dctx->dictContentEndForFuzzing;
#endif
    out->dctx_size = sizeof(*dctx);
}

size_t ZSTD_rust_dctx_sizeof(void)
{
    return sizeof(ZSTD_DCtx);
}

void ZSTD_dctx_init_platform(ZSTD_DCtx* dctx)
{
#if DYNAMIC_BMI2
    ZSTD_rust_dctx_init_platform(&dctx->bmi2, DYNAMIC_BMI2);
#else
    (void)dctx;
    ZSTD_rust_dctx_init_platform(NULL, DYNAMIC_BMI2);
#endif
}

size_t ZSTD_rust_dctx_default_max_window_size(void)
{
    return ZSTD_MAXWINDOWSIZE_DEFAULT;
}

int ZSTD_rust_no_forward_progress_max(void)
{
    return ZSTD_NO_FORWARD_PROGRESS_MAX;
}

int ZSTD_rust_heapmode(void)
{
    return ZSTD_HEAPMODE;
}

size_t ZSTD_rust_decompress_stack(void* dst, size_t dstCapacity,
                                  const void* src, size_t srcSize)
{
    ZSTD_DCtx dctx;
    ZSTD_rustDecompressStackProjection const projection = {
        ZSTD_HEAPMODE,
        &dctx,
        sizeof(dctx),
        dst,
        dstCapacity,
        src,
        srcSize
    };
    ZSTD_rustDecompressStackCallbacks const callbacks = {
        ZSTD_initStaticDCtx,
        ZSTD_rust_decompress_stack_context
    };
    return ZSTD_rust_decompress_stack_action(&projection, &callbacks);
}

void ZSTD_rust_dctx_trace_view(ZSTD_DCtx* dctx,
                               ZSTD_rustDctxTraceView* out)
{
    ZSTD_memset(out, 0, sizeof(*out));
    out->dctx = dctx;
#if ZSTD_TRACE
    out->trace_ctx = &dctx->traceCtx;
    out->begin = (ZSTD_trace_decompress_begin != NULL)
        ? ZSTD_rust_trace_begin_callback : NULL;
    out->end = (ZSTD_trace_decompress_end != NULL)
        ? ZSTD_rust_trace_end_callback : NULL;
    out->ddict = dctx->ddict;
    out->dictionary_is_cold = dctx->ddictIsCold;
#endif
}

/* 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) \
    && (ZSTD_LEGACY_SUPPORT <= 7)
    return ZSTD_LEGACY_SUPPORT;
#else
    return 0;
#endif
}