_lfn_gen_short_fname

Syntax

#include <fcntl.h>

char _lfn_gen_short_fname (const char *long_fname, char *short_fname);

Description

This function generates a short (8+3) filename alias for the long filename pointed to by long_fname and puts it into the buffer pointed to by short_fname. It uses the same algorithm that Windows 9x uses, with the exception that the returned short name will never have a numeric tail, because this function doesn't check the directory to see whether the generated short name will collide with any other file in the directory. Note that long_fname must contain only the name part of a file; elements of a full pathname (like : or / are not allowed (they will cause the function to fail). short_fname will be returned upper-cased, since that is how 8+3 filenames are stored in directory entries.

When the LFN API is not supported (see section _use_lfn), the function simply converts up to 12 characters of long_fname to upper-case and returns that. It will do the same if long_fname includes any characters illegal in a filename.

You might need to call this function if you want to know whether a given filename is valid on MSDOS: if a case-sensitive string comparison function such as strcmp (see section strcmp) returns a 0 when it compares the original long filename with the short one returned by _lfn_gen_short_fname, then the filename is a valid DOS name. (Note that if long_fname is in lower case, it might not compare equal with short_fname because of the case difference.)

Return value

The function returns a pointer to short_fname.

Example

#include <stdio.h>
#include <string.h>
#include <fcntl.h>

int dos_check (char *fname)
{
  char fshort[13];
  int retval;

  if (stricmp (_lfn_gen_short_fname (fname, fshort), fname) == 0)
  {
    printf ("%s is a valid MSDOS 8+3 filename\n", fname);
    retval = 1;
  }
  else
  {
    printf ("%s will have to be changed for MSDOS\n", fname);
    retval = 0;
  }
  return retval;
}

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