Method underflow

src/Abyss/FileSystem/MPQ.cpp:48–61

std::streamsize MPQStream::StartOfBlockForTesting() const { return _startOfBlock; }

int MPQStream::underflow() {
    if (gptr() == egptr()) {
        _startOfBlock += egptr() - eback();
        DWORD amountRead;
        if (!SFileReadFile(_mpqFile, _buffer, sizeof(_buffer), &amountRead, nullptr)) {
            if (GetLastError() != ERROR_HANDLE_EOF) {
                throw std::runtime_error("Error reading file from MPQ");
            }
        }
        setg(_buffer, _buffer, _buffer + amountRead);
    }

    return gptr() == egptr() ? traits_type::eof() : traits_type::to_int_type(*gptr());
}

std::streambuf::pos_type MPQStream::seekpos(const pos_type pos, const std::ios_base::openmode which) { return seekoff(pos, std::ios_base::beg, which); }