view release on metacpan or  search on metacpan

ext/zstd/lib/decompress/zstd_decompress.c  view on Meta::CPAN

 */
static size_t ZSTD_decompressContinueStream(
            ZSTD_DStream* zds, char** op, char* oend,
            void const* src, size_t srcSize) {
    int const isSkipFrame = ZSTD_isSkipFrame(zds);
    if (zds->outBufferMode == ZSTD_bm_buffered) {
        size_t const dstSize = isSkipFrame ? 0 : zds->outBuffSize - zds->outStart;
        size_t const decodedSize = ZSTD_decompressContinue(zds,
                zds->outBuff + zds->outStart, dstSize, src, srcSize);
        FORWARD_IF_ERROR(decodedSize, "");
        if (!decodedSize && !isSkipFrame) {
            zds->streamStage = zdss_read;
        } else {
            zds->outEnd = zds->outStart + decodedSize;
            zds->streamStage = zdss_flush;
        }
    } else {
        /* Write directly into the output buffer */
        size_t const dstSize = isSkipFrame ? 0 : (size_t)(oend - *op);
        size_t const decodedSize = ZSTD_decompressContinue(zds, *op, dstSize, src, srcSize);
        FORWARD_IF_ERROR(decodedSize, "");
        *op += decodedSize;
        /* Flushing is not needed. */
        zds->streamStage = zdss_read;
        assert(*op <= oend);
        assert(zds->outBufferMode == ZSTD_bm_stable);
    }
    return 0;
}

size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input)
{
    const char* const src = (const char*)input->src;
    const char* const istart = input->pos != 0 ? src + input->pos : src;
    const char* const iend = input->size != 0 ? src + input->size : src;
    const char* ip = istart;
    char* const dst = (char*)output->dst;
    char* const ostart = output->pos != 0 ? dst + output->pos : dst;
    char* const oend = output->size != 0 ? dst + output->size : dst;
    char* op = ostart;
    U32 someMoreWork = 1;

    DEBUGLOG(5, "ZSTD_decompressStream");
    RETURN_ERROR_IF(
        input->pos > input->size,
        srcSize_wrong,
        "forbidden. in: pos: %u   vs size: %u",
        (U32)input->pos, (U32)input->size);
    RETURN_ERROR_IF(
        output->pos > output->size,
        dstSize_tooSmall,
        "forbidden. out: pos: %u   vs size: %u",
        (U32)output->pos, (U32)output->size);
    DEBUGLOG(5, "input size : %u", (U32)(input->size - input->pos));
    FORWARD_IF_ERROR(ZSTD_checkOutBuffer(zds, output), "");

    while (someMoreWork) {
        switch(zds->streamStage)
        {
        case zdss_init :
            DEBUGLOG(5, "stage zdss_init => transparent reset ");
            zds->streamStage = zdss_loadHeader;
            zds->lhSize = zds->inPos = zds->outStart = zds->outEnd = 0;
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
            zds->legacyVersion = 0;
#endif
            zds->hostageByte = 0;
            zds->expectedOutBuffer = *output;
            ZSTD_FALLTHROUGH;

        case zdss_loadHeader :
            DEBUGLOG(5, "stage zdss_loadHeader (srcSize : %u)", (U32)(iend - ip));
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
            if (zds->legacyVersion) {
                RETURN_ERROR_IF(zds->staticSize, memory_allocation,
                    "legacy support is incompatible with static dctx");
                {   size_t const hint = ZSTD_decompressLegacyStream(zds->legacyContext, zds->legacyVersion, output, input);
                    if (hint==0) zds->streamStage = zdss_init;
                    return hint;
            }   }
#endif
            {   size_t const hSize = ZSTD_getFrameHeader_advanced(&zds->fParams, zds->headerBuffer, zds->lhSize, zds->format);
                if (zds->refMultipleDDicts && zds->ddictSet) {
                    ZSTD_DCtx_selectFrameDDict(zds);
                }
                if (ZSTD_isError(hSize)) {
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
                    U32 const legacyVersion = ZSTD_isLegacy(istart, iend-istart);
                    if (legacyVersion) {
                        ZSTD_DDict const* const ddict = ZSTD_getDDict(zds);
                        const void* const dict = ddict ? ZSTD_DDict_dictContent(ddict) : NULL;
                        size_t const dictSize = ddict ? ZSTD_DDict_dictSize(ddict) : 0;
                        DEBUGLOG(5, "ZSTD_decompressStream: detected legacy version v0.%u", legacyVersion);
                        RETURN_ERROR_IF(zds->staticSize, memory_allocation,
                            "legacy support is incompatible with static dctx");
                        FORWARD_IF_ERROR(ZSTD_initLegacyStream(&zds->legacyContext,
                                    zds->previousLegacyVersion, legacyVersion,
                                    dict, dictSize), "");
                        zds->legacyVersion = zds->previousLegacyVersion = legacyVersion;
                        {   size_t const hint = ZSTD_decompressLegacyStream(zds->legacyContext, legacyVersion, output, input);
                            if (hint==0) zds->streamStage = zdss_init;   /* or stay in stage zdss_loadHeader */
                            return hint;
                    }   }
#endif
                    return hSize;   /* error */
                }
                if (hSize != 0) {   /* need more input */
                    size_t const toLoad = hSize - zds->lhSize;   /* if hSize!=0, hSize > zds->lhSize */
                    size_t const remainingInput = (size_t)(iend-ip);
                    assert(iend >= ip);
                    if (toLoad > remainingInput) {   /* not enough input to load full header */
                        if (remainingInput > 0) {
                            ZSTD_memcpy(zds->headerBuffer + zds->lhSize, ip, remainingInput);
                            zds->lhSize += remainingInput;
                        }
                        input->pos = input->size;
                        /* check first few bytes */
                        FORWARD_IF_ERROR(
                            ZSTD_getFrameHeader_advanced(&zds->fParams, zds->headerBuffer, zds->lhSize, zds->format),
                            "First few bytes detected incorrect" );
                        /* return hint input size */