}

    @Override
    public void write(char[] cbuf, int off, int len) {
      checkPositionIndexes(off, off + len, cbuf.length);
    }

    @Override
    public void write(String str) {
      checkNotNull(str);
    }

    @Override
    public void write(String str, int off, int len) {
      checkPositionIndexes(off, off + len, str.length());
    }

    @Override

    int readSetupWireFormat(final byte[] buffer, final int bufferIndex, final int len) {
        return 0;
    }

    @Override
    int readParametersWireFormat(final byte[] buffer, final int bufferIndex, final int len) {
        return 0;
    }

    @Override
    int readDataWireFormat(final byte[] buffer, final int bufferIndex, final int len) {
        return 0;
    }

    @Override
    public String toString() {

        return 0;
    }

    @Override
    protected int readSetupWireFormat(final byte[] buffer, final int bufferIndex, final int len) {
        return 0;
    }

    @Override
    protected int readParametersWireFormat(final byte[] buffer, int bufferIndex, final int len) {
        final int start = bufferIndex;
        setStatus(SMBUtil.readInt2(buffer, bufferIndex));
        bufferIndex += 2;

    abstract int writeDataWireFormat(byte[] dst, int dstIndex);

    abstract int readSetupWireFormat(byte[] buffer, int bufferIndex, int len);

    abstract int readParametersWireFormat(byte[] buffer, int bufferIndex, int len);

    abstract int readDataWireFormat(byte[] buffer, int bufferIndex, int len);

    @Override
    public String toString() {

     * {@inheritDoc}
     *
     * @see jcifs.Decodable#decode(byte[], int, int)
     */
    @Override
    public int decode(final byte[] buffer, int bufferIndex, final int len) throws SMBProtocolDecodingException {
        final int start = bufferIndex;
        if (len < 24) {
            throw new SMBProtocolDecodingException("Invalid resume key");
        }

        this.resumeKey = new byte[24];

        byte[] dk = new byte[klen];
        for (int n = 0; n < klen;) {
            byte[] block = cipher.doFinal(enc);
            int len = Math.min(klen - n, block.length);
            System.arraycopy(block, 0, dk, n, len);
            n += len;
            enc = block;
        }
        return dk;
    }

    /**
     * Performs n-fold expansion of data as specified in RFC 3961.

     */
    public static int readn(final InputStream in, final byte[] b, final int off, final int len) throws IOException {
        int i = 0, n = -5;

        while (i < len) {
            n = in.read(b, off + i, len - i);
            if (n <= 0) {
                break;
            }
            i += n;
        }

        return i;
    }

    /* state values
     * 0 - not connected
     * 1 - connecting

     * @param bufferIndex the starting index in the buffer
     * @param len the maximum length of data to decode
     * @return decoded length
     * @throws SMBProtocolDecodingException if decoding fails
     */
    int decode(byte[] buffer, int bufferIndex, int len) throws SMBProtocolDecodingException;

    }

    static int readn(final InputStream in, final byte[] b, final int off, final int len) throws IOException {
        int i = 0, n;

        while (i < len) {
            n = in.read(b, off + i, len - i);
            if (n <= 0) {
                break;
            }
            i += n;
        }

        return i;
    }

    }

    @Test
    @DisplayName("initSecContext with null buffer and non-zero len throws NPE")
    void testInitSecContextNullBufferNonZeroLen() throws Exception {
        SpnegoContext ctx = newContext();
        // A null buffer with non-zero len leads to NPE while slicing input
        assertThrows(NullPointerException.class, () -> ctx.initSecContext(null, 0, 1));