static byte[] loadBinaryFilePart(File file, long start, long end) ctex {
  if (file == null) null;
  RandomAccessFile raf = new RandomAccessFile(file, "r");
  int n = toInt(min(raf.length(), end-start));
  byte[] buffer = new byte[n];
  try {
    raf.seek(start);
    raf.readFully(buffer, 0, n);
    return buffer;
  } finally {
    raf.close();
  }
}