The implementation of skip() in java.io.InputStream:

    public long skip(long n) throws IOException {
        /* ensure that the number is a positive int */
        byte data[] = new byte[(int) (n & 0xEFFFFFFF)];
        return read(data);
    }

First off, the bit mask above must just be a typo; it should be 0x7FFFFFFF.
As it is, it allows negative integers to be used for the array size, resulting
in a NegativeArraySizeException.

Second, since it calls read(), it could return -1 if there is EOF before any
bytes could be skipped. [Although I would argue that this is the way it
*should* be,] the JLS states that it should still return only zero in this
case (section 22.3.4).