INFO: Long Filenames on Windows NT FAT Partitions

• Microsoft Win32 Application Programming Interface (API) included with: - Microsoft Windows NT versions 3.5, 3.51, 4.0

SUMMARY

Windows NT, versions 3.5, 3.51, and 4.0 have the ability to create or open files with long filenames (LFN) on Windows NT file allocation table (FAT) partitions.

UNICODE is stored on disk, so that the original name is always preserved for extended characters regardless of which code page happens to be active when reading from or writing to the disk.

The legal character set is that of the Windows NT file system (NTFS) (except for the ":" for opening NTFS alternative file streams), so you can copy arbitrary files between NTFS and FAT without losing any of the filename information.

MORE INFORMATION

The LFNs are not available from the MS-DOS DIR command, but they are available from the Windows NT DIR command. When you create an LFN on a Windows NT FAT partition, an accompanying short name is created just as on an NTFS partition. You can access the file or directory with either the long names or the short names under Windows NT.

For example, use the Microsoft Editor (MEP) to create a file named as follows on a FAT partition under Windows NT:

   longfilename.fat

   longfi~1.fat

The same result can also be achieved programmatically. Build and run the following sample code on Windows NT:

Sample Code

   #include <windows.h>

   void main( )
   {
      WIN32_FIND_DATA fd;
      char buf[80];

      FindFirstFile( "long*", &fd );
      wsprintf( buf, "File name is %s", fd.cFileName );
      MessageBox( NULL, buf, "Test", MB_OK );
      wsprintf( buf, "Alternate file name is %s", fd.cAlternateFileName );
      MessageBox( NULL, buf, "Test", MB_OK );
   }

   File name is longfilename.fat

   Alternate file name is longfi~1.fat

Keywords          : BseFileio
Version           : WINNT:3.5,3.51,4.0;
Platform          : winnt
Issue type        : kbinfo