content: /*
   * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package java.security;
  
  import java.io.IOException;
  import java.io.EOFException;
  import java.io.OutputStream;
  import java.io.FilterOutputStream;
  import java.io.PrintStream;
  import java.io.ByteArrayOutputStream;
  
  /**
   * A transparent stream that updates the associated message digest using
   * the bits going through the stream.
   *
   * <p>To complete the message digest computation, call one of the
   * {@code digest} methods on the associated message
   * digest after your calls to one of this digest output stream's
   * {@link #write(int) write} methods.
   *
   * <p>It is possible to turn this stream on or off (see
   * {@link #on(boolean) on}). When it is on, a call to one of the
   * {@code write} methods results in
   * an update on the message digest.  But when it is off, the message
   * digest is not updated. The default is for the stream to be on.
   *
   * @see MessageDigest
   * @see DigestInputStream
   *
   * @author Benjamin Renaud
   */
  public class DigestOutputStream extends FilterOutputStream {
  
      private boolean on = true;
  
      /**
       * The message digest associated with this stream.
       */
      protected MessageDigest digest;
  
      /**
       * Creates a digest output stream, using the specified output stream
       * and message digest.
       *
       * @param stream the output stream.
       *
       * @param digest the message digest to associate with this stream.
       */
      public DigestOutputStream(OutputStream stream, MessageDigest digest) {
          super(stream);
          setMessageDigest(digest);
      }
  
      /**
       * Returns the message digest associated with this stream.
       *
       * @return the message digest associated with this stream.
       * @see #setMessageDigest(MessageDigest)
       */
      public MessageDigest getMessageDigest() {
          return digest;
      }
  
      /**
       * Associates the specified message digest with this stream.
       *
       * @param digest the message digest to be associated with this stream.
       * @see #getMessageDigest()
       */
      public void setMessageDigest(MessageDigest digest) {
          this.digest = digest;
      }
  
      /**
       * Updates the message digest (if the digest function is on) using
       * the specified byte, and in any case writes the byte
       * to the output stream. That is, if the digest function is on
       * (see {@link #on(boolean) on}), this method calls
       * {@code update} on the message digest associated with this
       * stream, passing it the byte {@code b}. This method then
       * writes the byte to the output stream, blocking until the byte
       * is actually written.
       *
       * @param b the byte to be used for updating and writing to the
       * output stream.
       *
       * @exception IOException if an I/O error occurs.
       *
       * @see MessageDigest#update(byte)
       */
      public void write(int b) throws IOException {
          out.write(b);
          if (on) {
              digest.update((byte)b);
          }
      }
  
      /**
       * Updates the message digest (if the digest function is on) using
       * the specified subarray, and in any case writes the subarray to
       * the output stream. That is, if the digest function is on (see
       * {@link #on(boolean) on}), this method calls {@code update}
       * on the message digest associated with this stream, passing it
       * the subarray specifications. This method then writes the subarray
       * bytes to the output stream, blocking until the bytes are actually
       * written.
       *
       * @param b the array containing the subarray to be used for updating
       * and writing to the output stream.
       *
       * @param off the offset into {@code b} of the first byte to
       * be updated and written.
       *
       * @param len the number of bytes of data to be updated and written
       * from {@code b}, starting at offset {@code off}.
       *
       * @exception IOException if an I/O error occurs.
       *
       * @see MessageDigest#update(byte[], int, int)
       */
      public void write(byte[] b, int off, int len) throws IOException {
          // BEGIN Android-added: perform checks for parameters first.
          // See org.apache.harmony.security.tests.j.s.DigestOutputStreamTest#test_write$BII_6
          if (b == null || off + len > b.length) {
              throw new IllegalArgumentException("wrong parameters for write");
          }
          if (off < 0 || len < 0) {
              throw new IndexOutOfBoundsException("wrong index for write");
          }
          // END Android-added: perform checks for parameters first.
          out.write(b, off, len);
          if (on) {
              digest.update(b, off, len);
          }
      }
  
      /**
       * Turns the digest function on or off. The default is on.  When
       * it is on, a call to one of the {@code write} methods results in an
       * update on the message digest.  But when it is off, the message
       * digest is not updated.
       *
       * @param on true to turn the digest function on, false to turn it
       * off.
       */
      public void on(boolean on) {
          this.on = on;
      }
  
      /**
       * Prints a string representation of this digest output stream and
       * its associated message digest object.
       */
       public String toString() {
           return "[Digest Output Stream] " + digest.toString();
       }
  }
  