readfile读写磁盘扇区时偏移量超出DWORD范围怎么办

Question

现在我正在通过createfile和readfile函数直接读磁盘扇区，OVERLAPPED结构的offset是DWORD类型，最大值为4294967295，当需要读取的扇区号大于8388607时，偏移量超出这个最大值，读取失败，请问这种情况应该如何解决呢？setfilepointer有用吗？
代码如下

//作用：打开逻辑磁盘设备
//参数：逻辑盘符  
//返回值：该逻辑磁盘的句柄  
HANDLE OpenDisk(char devName[7]) {
    HANDLE handle = CreateFile(devName, GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
    if (handle == INVALID_HANDLE_VALUE)
        return 0;
    else
        return handle;
}

//作用：读磁盘的指定扇区
//参数：逻辑磁盘句柄，输出的字符串指针，起始扇区号，长度  
//返回值：读取的大小  
DWORD ReadDisk(HANDLE handle, unsigned char*& out, DWORD start, DWORD size)
{
    OVERLAPPED over = { 0 };
    over.Offset = start * 512;
    unsigned char* buffer = new unsigned char[size + 1];
    DWORD readsize;
    ReadFile(handle, buffer, size, &readsize, &over);
    buffer[size] = 0;
    out = buffer;
    return size;
}  

Answer 1

分两个32DWORD存储。