[Neftali [Germán.Estévez]]

Las RxLib, en la unit FileUtil.pas tienen la siguiente función, que tal vez te sea útil (te pongo la 4):

Código Delphi [-]
function ShortToLongFileName(const ShortName: string): string;
var
  Temp: TWin32FindData;
  SearchHandle: THandle;
begin
  SearchHandle := FindFirstFile(PChar(ShortName), Temp);
  if SearchHandle <> INVALID_HANDLE_VALUE then begin
    Result := string(Temp.cFileName);
    if Result = '' then Result := string(Temp.cAlternateFileName);
  end
  else Result := '';
  Windows.FindClose(SearchHandle);
end;

function LongToShortFileName(const LongName: string): string;
var
  Temp: TWin32FindData;
  SearchHandle: THandle;
begin
  SearchHandle := FindFirstFile(PChar(LongName), Temp);
  if SearchHandle <> INVALID_HANDLE_VALUE then begin
    Result := string(Temp.cAlternateFileName);
    if Result = '' then Result := string(Temp.cFileName);
  end
  else Result := '';
  Windows.FindClose(SearchHandle);
end;

function ShortToLongPath(const ShortName: string): string;
var
  LastSlash: PChar;
  TempPathPtr: PChar;
begin
  Result := '';
  TempPathPtr := PChar(ShortName);
  LastSlash := StrRScan(TempPathPtr, '\');
  while LastSlash <> nil do begin
    Result := '\' + ShortToLongFileName(TempPathPtr) + Result;
    if LastSlash <> nil then begin
      LastSlash^ := char(0);
      LastSlash := StrRScan(TempPathPtr, '\');
    end;
  end;
  Result := TempPathPtr + Result;
end;

function LongToShortPath(const LongName: string): string;
var
  LastSlash: PChar;
  TempPathPtr: PChar;
begin
  Result := '';
  TempPathPtr := PChar(LongName);
  LastSlash := StrRScan(TempPathPtr, '\');
  while LastSlash <> nil do begin
    Result := '\' + LongToShortFileName(TempPathPtr) + Result;
    if LastSlash <> nil then begin
      LastSlash^ := char(0);
      LastSlash := StrRScan(TempPathPtr, '\');
    end;
  end;
  Result := TempPathPtr + Result;
end;