Function ZSTD_decompressMultiFrame

freebsd/contrib/openzfs/module/zstd/lib/zstd.c:25200–25291

}

static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
                                        void* dst, size_t dstCapacity,
                                  const void* src, size_t srcSize,
                                  const void* dict, size_t dictSize,
                                  const ZSTD_DDict* ddict)
{
    void* const dststart = dst;
    int moreThan1Frame = 0;

    DEBUGLOG(5, "ZSTD_decompressMultiFrame");
    assert(dict==NULL || ddict==NULL);  /* either dict or ddict set, not both */

    if (ddict) {
        dict = ZSTD_DDict_dictContent(ddict);
        dictSize = ZSTD_DDict_dictSize(ddict);
    }

    while (srcSize >= ZSTD_startingInputLength(dctx->format)) {

#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
        if (ZSTD_isLegacy(src, srcSize)) {
            size_t decodedSize;
            size_t const frameSize = ZSTD_findFrameCompressedSizeLegacy(src, srcSize);
            if (ZSTD_isError(frameSize)) return frameSize;
            RETURN_ERROR_IF(dctx->staticSize, memory_allocation,
                "legacy support is not compatible with static dctx");

            decodedSize = ZSTD_decompressLegacy(dst, dstCapacity, src, frameSize, dict, dictSize);
            if (ZSTD_isError(decodedSize)) return decodedSize;

            assert(decodedSize <=- dstCapacity);
            dst = (BYTE*)dst + decodedSize;
            dstCapacity -= decodedSize;

            src = (const BYTE*)src + frameSize;
            srcSize -= frameSize;

            continue;
        }
#endif

        {   U32 const magicNumber = MEM_readLE32(src);
            DEBUGLOG(4, "reading magic number %08X (expecting %08X)",
                        (unsigned)magicNumber, ZSTD_MAGICNUMBER);
            if ((magicNumber & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) {
                size_t const skippableSize = readSkippableFrameSize(src, srcSize);
                FORWARD_IF_ERROR(skippableSize, "readSkippableFrameSize failed");
                assert(skippableSize <= srcSize);

                src = (const BYTE *)src + skippableSize;
                srcSize -= skippableSize;
                continue;
        }   }

        if (ddict) {
            /* we were called from ZSTD_decompress_usingDDict */
            FORWARD_IF_ERROR(ZSTD_decompressBegin_usingDDict(dctx, ddict), "");
        } else {