Method isNeedToAddEmptyBlock

src/IO/ZstdDeflatingAppendableWriteBuffer.cpp:188–212

bool ZstdDeflatingAppendableWriteBuffer::isNeedToAddEmptyBlock()
{
    auto reader = read_buffer_creator();
    auto fsize = reader->getFileSize();
    if (fsize > 3)
    {
        std::array<char, 3> result{};
        reader->seek(fsize - 3, SEEK_SET);
        reader->readStrict(result.data(), 3);

        /// If we don't have correct block in the end, then we need to add it manually.
        /// NOTE: maybe we can have the same bytes in case of data corruption/unfinished write.
        /// But in this case file still corrupted and we have to remove it.
        return result != ZSTD_CORRECT_TERMINATION_LAST_BLOCK;
    }
    if (fsize > 0)
    {
        throw Exception(
            ErrorCodes::ZSTD_ENCODER_FAILED,
            "Trying to write to non-empty file '{}' with tiny size {}. It can lead to data corruption",
            out->getFileName(),
            fsize);
    }
    return false;
}

void ZstdDeflatingAppendableWriteBuffer::cancelImpl() noexcept
{