#define INCL_NOPM
#define INCL_DOSERRORS
#include <os2.h>

#include <stdlib.h>
#include <string.h>
#include <ctype.h>

int IsFileNameValid(char *name)
{
  HFILE hf;
#ifdef OS2_16
  USHORT uAction;
#else
  ULONG uAction;
#endif

  if ( _osmode == DOS_MODE )
    return FALSE;

  switch( DosOpen(name, &hf, &uAction, 0L, 0, FILE_OPEN,
                  OPEN_ACCESS_READONLY | OPEN_SHARE_DENYNONE, 0L) )
  {
  case ERROR_INVALID_NAME:
  case ERROR_FILENAME_EXCED_RANGE:
    return FALSE;
  case NO_ERROR:
    DosClose(hf);
  default:
    return TRUE;
  }
}

void ChangeNameForFAT(char *name)
{
  char *src, *dst, *next, *ptr, *dot, *start;
  static char invalid[] = ":;,=+\"[]<>| \t";

  if ( isalpha(name[0]) && (name[1] == ':') )
    start = name + 2;
  else
    start = name;

  src = dst = start;
  if ( (*src == '/') || (*src == '\\') )
    src++, dst++;

  while ( *src )
  {
    for ( next = src; *next && (*next != '/') && (*next != '\\'); next++ );

    for ( ptr = src, dot = NULL; ptr < next; ptr++ )
      if ( *ptr == '.' )
      {
        dot = ptr; /* remember last dot */
        *ptr = '_';
      }

    if ( dot == NULL )
      for ( ptr = src; ptr < next; ptr++ )
        if ( *ptr == '_' )
          dot = ptr; /* remember last _ as if it were a dot */

    if ( dot && (dot > src) &&
         ((next - dot <= 4) ||
          ((next - src > 8) && (dot - src > 3))) )
    {
      if ( dot )
        *dot = '.';

      for ( ptr = src; (ptr < dot) && ((ptr - src) < 8); ptr++ )
        *dst++ = *ptr;

      for ( ptr = dot; (ptr < next) && ((ptr - dot) < 4); ptr++ )
        *dst++ = *ptr;
    }
    else
    {
      if ( dot && (next - src == 1) )
        *dot = '.';           /* special case: "." as a path component */

      for ( ptr = src; (ptr < next) && ((ptr - src) < 8); ptr++ )
        *dst++ = *ptr;
    }

    *dst++ = *next; /* either '/' or 0 */

    if ( *next )
    {
      src = next + 1;

      if ( *src == 0 ) /* handle trailing '/' on dirs ! */
        *dst = 0;
    }
    else
      break;
  }

  for ( src = start; *src != 0; ++src )
    if ( (strchr(invalid, *src) != NULL) || (*src == ' ') )
        *src = '_';
}