Shorten filename if necessary

  define("FILENAME_MAX_LENGTH",     10);

  $file1_name = "myfilenameisthis.txt";

  //Shorten the file name if its too long
  $FilenameExtension = pathinfo($file1_name, PATHINFO_EXTENSION);
  $FilenameBasename = pathinfo($file1_name, PATHINFO_FILENAME);
  $FilenameExtension = $FilenameExtension ? '.' . $FilenameExtension : '';   //If extension is present, add the dot
  $MaxBasenameLength = FILENAME_MAX_LENGTH - strlen($FilenameExtension);

  if ($MaxBasenameLength < 1)
  {
    //Not enough space for even 1 character of the basename
    $file1_name = substr($FilenameBasename, 0, 1) . $FilenameExtension;   //<<<<<THIS WILL BE TOO LONG!!!!
  }
  else if (strlen($FilenameBasename) > $MaxBasenameLength)
  {
    //Filename needs shortening
    $file1_name = substr($FilenameBasename, 0, $MaxBasenameLength) . $FilenameExtension;
  }
  else
  {
    //No need to shorten
    //$file1_name = $file1_name;
  }