@Override
    public final int available() {
        return ofinish - ostart;
    }
Returns the number of bytes that can be read from this input
stream without blocking. The <code>available</code> method of
<code>InputStream</code> returns <code>0</code>. This method
<B>should</B> be overridden by subclasses.

@return the number of bytes that can be read from this input stream
without blocking.
src/main/java/org/gaul/s3proxy/crypto/DecryptionInputStream.java