@Override
  public void moveTo(long position) {
    if (position < 0 || length() < position) {
      throw new IllegalArgumentException("Position out of the bounds of the file!");
    }

    fp = position;
  }
@Test
  public void available() throws IOException {
    int amount = 12;
    cs.moveTo((int) len - amount);
    assertEquals(amount, cs.availableExact());
  }