Function zlibDecompress

src/openrct2/core/Compression.cpp:85–141

    }

    bool zlibDecompress(IStream& source, uint64_t sourceLength, IStream& dest, uint64_t decompressLength, ZlibHeaderType header)
    {
        if (sourceLength > source.GetLength() - source.GetPosition())
            throw IOException("Not Enough Data to Decompress");

        StreamReadBuffer sourceBuf(source, sourceLength, kZlibChunkSize);
        StreamWriteBuffer destBuf(dest, decompressLength, kZlibChunkSize);

        z_stream strm{};
        int ret = inflateInit2(&strm, kZlibWindowBits[static_cast<int>(header)]);
        if (ret != Z_OK)
        {
            LOG_ERROR("Failed to initialise stream");
            return false;
        }

        do
        {
            auto readBlock = sourceBuf.ReadBlock(source, kZlibMaxChunkSize);
            strm.next_in = static_cast<const Bytef*>(readBlock.first);
            strm.avail_in = static_cast<uInt>(readBlock.second);

            do
            {
                if (!destBuf)
                {
                    LOG_ERROR("Decompressed data larger than expected");
                    inflateEnd(&strm);
                    return false;
                }

                auto writeBlock = destBuf.WriteBlockStart(kZlibMaxChunkSize);
                strm.next_out = static_cast<Bytef*>(writeBlock.first);
                strm.avail_out = static_cast<uInt>(writeBlock.second);

                ret = inflate(&strm, sourceBuf ? Z_NO_FLUSH : Z_FINISH);
                if (ret == Z_STREAM_ERROR)
                {
                    LOG_ERROR("Failed to decompress data");
                    inflateEnd(&strm);
                    return false;
                }

                destBuf.WriteBlockCommit(dest, writeBlock.second - strm.avail_out);
            } while (strm.avail_in > 0);
        } while (sourceBuf);

        if (destBuf)
        {
            LOG_ERROR("Decompressed data smaller than expected");
            inflateEnd(&strm);
            return false;
        }

        inflateEnd(&strm);
        return true;
    }