throw new IllegalArgumentException(); if (amount > end - filepos) amount = end - filepos; filepos += amount;
return 0; if (amount > end - (bufferOffset + pos)) amount = end - (bufferOffset + pos); seek(bufferOffset + pos + amount);
    public long skip(long amount)    {			if (amount < 0)				throw new IllegalArgumentException();			if (amount > end - filepos)				amount = end - filepos;			filepos += amount;			return amount;		}