请教关于FSCTL_GET_RETRIEVAL_POINTERS的问题,谢了!
先看代码:
#define WINVER 0x0501
#define _WIN32_WINNT 0x0501
#include <iostream>
#include <windows.h>
#include <tchar.h>
#include <Winioctl.h>
int main()
{
HANDLE hFile;
DWORD dwRet = 0;
hFile = CreateFile(_T("C:\\2.txt"), GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, 0, OPEN_EXISTING, FILE_FLAG_NO_BUFFERING, 0);
if (hFile != INVALID_HANDLE_VALUE)
{
STARTING_VCN_INPUT_BUFFER InBuf;
RETRIEVAL_POINTERS_BUFFER OutBuf;
DWORD dwBytesRet;
InBuf.StartingVcn.QuadPart = 0;
ZeroMemory(&OutBuf, sizeof(OutBuf));
DeviceIoControl(hFile, FSCTL_GET_RETRIEVAL_POINTERS, &InBuf, sizeof(InBuf), &OutBuf, sizeof(OutBuf), &dwBytesRet, NULL);
dwRet = GetLastError();
CloseHandle(hFile);
}
return dwRet;
}
当2.txt这个文件很小时,DeviceIoControl总是返回ERROR_HANDLE_EOF,但是当我增大2.txt到一定大小时,DeviceIoControl就成功了,而且再减小2.txt到原来的大小DeviceIoControl还是能执行成功,为什么呢???C盘为NTFS格式