使用 Win32 API 函数 ReadFile 和 WriteFile 将代码迁移到 Linux 的正确方法

问：

我有一个使用 Win32 API 函数的自定义流实现，例如 、 。此外，流实现和函数不受 （它刷新其内部缓冲区，但不刷新操作系统缓冲区）：::CreateFile2::ReadFile::WriteFileFlushTruncatestd::fstreamflush()

class WinStream : public IoStream
{
public:

    size_t Read(uint8_t* buffer, size_t count) override
    {
        const DWORD nNumberOfBytesToRead = static_cast<DWORD>(count);
        assert(nNumberOfBytesToRead == count);
        DWORD NumberOfBytesRead = 0;

        Check(::ReadFile(m_hFile, buffer, nNumberOfBytesToRead, &NumberOfBytesRead, NULL) != FALSE);

        return NumberOfBytesRead;
    }

    void Write(const uint8_t* buffer, size_t count) override
    {
        const DWORD nNumberOfBytesToWrite = static_cast<DWORD>(count);
        assert(nNumberOfBytesToWrite == count);
        DWORD NumberOfBytesWritten = 0;

        if (::WriteFile(m_hFile, buffer, nNumberOfBytesToWrite, &NumberOfBytesWritten, NULL) == FALSE)
        {
            throw IoError(format()
                << _T("::WriteFile failed. This may indicate that the disk is full. Win32 Error: ")
                << ::GetLastError());
        }

        if (nNumberOfBytesToWrite != NumberOfBytesWritten)
        {
            throw IoError(format() << _T("Requested ") << nNumberOfBytesToWrite
                << _T(" bytes, but actually written ") << NumberOfBytesWritten << _T("."));
        }

    bool End() override
    {
        return GetFileSizeHelper() == GetFilePointerHelper();
    }

    void Seek(std::size_t pos, bool begin = true) override
    {
        LARGE_INTEGER li;

        li.QuadPart = pos;

        Check(::SetFilePointerEx(m_hFile, li, NULL, begin ? FILE_BEGIN : FILE_END) != INVALID_SET_FILE_POINTER);
    }

    void Move(std::ptrdiff_t offset) override
    {
        LARGE_INTEGER li;

        li.QuadPart = offset;

        Check(::SetFilePointerEx(m_hFile, li, NULL, FILE_CURRENT) != INVALID_SET_FILE_POINTER);
    }

    void Flush() override
    {
        Check(::FlushFileBuffers(m_hFile) != FALSE);
    }

    void Truncate() override
    {
        Check(::SetEndOfFile(m_hFile) != FALSE);
    }

private:

    void Check(bool success)
    {
        if (!success)
        {
            throw Win32Exception();
        }
    }
    
    LONGLONG GetFileSizeHelper()
    {
        LARGE_INTEGER li;

        li.QuadPart = 0;

        Check(::GetFileSizeEx(m_hFile, &li) != FALSE);

        return li.QuadPart;
    }

    LONGLONG GetFilePointerHelper()
    {
        LARGE_INTEGER liOfs = { 0 };
        LARGE_INTEGER liNew = { 0 };

        Check(::SetFilePointerEx(m_hFile, liOfs, &liNew, FILE_CURRENT) != INVALID_SET_FILE_POINTER);

        return liNew.QuadPart;
    }

    FileHandle m_hFile;
}

inline UniqueFileHandle CreateUniqueFile(const String& file_name)
{
    HANDLE hFile = ::CreateFile2(
        file_name.c_str(),
        GENERIC_READ | GENERIC_WRITE,
        0, //FILE_SHARE_READ | FILE_SHARE_WRITE,
        OPEN_ALWAYS,
        NULL //&extendedParams
    );

    if (hFile == INVALID_HANDLE_VALUE)
    {
        DWORD dw_err = ::GetLastError();

        throw IoError(format() << _T("Cannot open file ')" << file_name << "' for updating, error = " << dw_err));
    }

    return hFile;
}

将此代码迁移到 Linux 的正确（或现代）方法是什么？那么 Android、MacOS 和 iOS 呢？

它应该使用非缓冲读/写函数。