C / C++ / MFC

DWORD dwMappingStartOffset = 0,  // offset in file where the mapping starts
      dwMappingEndOffset = 0,    // offset where it ends
      dwStartingPosOffsetFromMappingStart = 0, // where to start parsing the file
                                               // (offset from dwMappingStartOffset)
      dwMappingSize = 0;  // size of file mapping object
//NOTE: m_dwLastSeenFileSize is already set to the size of the file the last time we parsed it
 
            // Get the system alloc granularity, the starting offset has to
            // be a multiple of that.
            SYSTEM_INFO si = {0};

            GetSystemInfo ( &si );
 
            // Calc the starting/ending offsets of the file that we'll read.
            dwMappingStartOffset = m_dwLastSeenFileSize;
            dwStartingPosOffsetFromMappingStart = dwMappingStartOffset % si.dwAllocationGranularity;
            dwMappingStartOffset -= dwStartingPosOffsetFromMappingStart;
            dwMappingEndOffset = dwFileSize - 1;
            dwMappingSize = dwMappingEndOffset - dwMappingStartOffset + 1;
 
    // Map the file (or just the end part) into memory.
    //NOTE: hFile was already opened w/CreateFile
HANDLE hMapping = CreateFileMapping ( hFile, NULL, PAGE_READONLY, 0, dwMappingSize, NULL );
 
    if ( NULL == hMapping )
        {
        CloseHandle ( hFile );
        return false;
        }
 
void* pvFileData = MapViewOfFile ( hMapping, FILE_MAP_READ, 0, dwMappingStartOffset, dwMappingSize );
 
    if ( NULL == pvFileData )
        {
        CloseHandle ( hMapping );
        CloseHandle ( hFile );
        return false;
        }