【跪求大神】关于直接读取NTFS硬盘扇区和FAT32优盘扇区的问题

Question

本帖最后由 great82149 于 2014-10-26 11:54:08 编辑

Answer 1

FAT32的数据区起始位置不是0, 读取前要额外计算
包括保留扇区, FAT, ....等参考BOOL CDiskFile::ReadDiskCluster(LARGE_INTEGER llFirstCluster, LARGE_INTEGER llCount, BYTE *pBuf)
{
LARGE_INTEGER llOffset;
LARGE_INTEGER llReadCount;
DWORD dwRetVal;
BOOL bResult;
DWORD dwReadSize; bResult = FALSE;
llOffset.QuadPart = llFirstCluster.QuadPart * m_dwBytesPerSector * m_dwSectorsPerCluster;
llOffset.QuadPart += m_dwFat32FirstDataSector * m_dwBytesPerSector;
dwRetVal = SetFilePointer(m_hVolume, llOffset.LowPart, &llOffset.HighPart, FILE_BEGIN);
if(dwRetVal == INVALID_SET_FILE_POINTER)
goto ReadDiskClusterDone; llReadCount.QuadPart = llCount.QuadPart * m_dwBytesPerSector * m_dwSectorsPerCluster;
if(llReadCount.HighPart != 0)
assert(0); bResult = ReadFile(m_hVolume, pBuf, llReadCount.LowPart, &dwReadSize, NULL);
if(bResult && llReadCount.QuadPart != dwReadSize)
goto ReadDiskClusterDone; bResult = TRUE;ReadDiskClusterDone:
return bResult;
}
................
DWORD dwReservedSectors;
DWORD dwFatSectors;
DWORD dwDirtoryTableSectors; dwReservedSectors = Boot.ReservedSectors;
dwFatSectors = Boot.BigSectorsPerFat * Boot.NumberOfFATs; //FAT32
dwDirtoryTableSectors = ((Boot.RootEntries * 32 - 1) / m_dwBytesPerSector + 1) * m_dwBytesPerSector; m_dwFat32FirstDataSector = dwReservedSectors + dwFatSectors + dwDirtoryTableSectors;