159 lines
4.8 KiB
Java
159 lines
4.8 KiB
Java
/* DigestOutputStream.java --- An output stream tied to a message digest
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Copyright (C) 1999, 2004, 2005 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.security;
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import java.io.FilterOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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/**
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* DigestOutputStream is a class that ties an OutputStream with a
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* MessageDigest. The Message Digest is used by the class to update it
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* self as bytes are written to the OutputStream.
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*
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* The updating to the digest depends on the on flag which is set to
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* true by default that tells the class to update the data in the
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* message digest.
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*
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* @version 0.0
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* @author Mark Benvenuto (ivymccough@worldnet.att.net)
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*/
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public class DigestOutputStream extends FilterOutputStream
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{
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/**
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* The message digest for the DigestOutputStream
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*/
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protected MessageDigest digest;
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//Manages the on flag
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private boolean state = true;
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/**
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* Constructs a new DigestOutputStream. It associates a
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* MessageDigest with the stream to compute the stream as data is
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* written.
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*
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* @param stream An OutputStream to associate this stream with
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* @param digest A MessageDigest to hash the stream with
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*/
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public DigestOutputStream(OutputStream stream, MessageDigest digest)
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{
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super(stream);
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this.digest = digest;
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}
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/**
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* Returns the MessageDigest associated with this DigestOutputStream
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*
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* @return The MessageDigest used to hash this stream
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*/
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public MessageDigest getMessageDigest()
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{
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return digest;
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}
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/**
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* Sets the current MessageDigest to current parameter
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*
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* @param digest A MessageDigest to associate with this stream
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*/
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public void setMessageDigest(MessageDigest digest)
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{
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this.digest = digest;
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}
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/**
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* Updates the hash if the on flag is true and then writes a byte to
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* the underlying output stream.
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*
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* @param b A byte to write to the output stream
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*
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* @exception IOException if the underlying output stream
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* cannot write the byte, this is thrown.
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*/
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public void write(int b) throws IOException
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{
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if (state)
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digest.update((byte) b);
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out.write(b);
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}
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/**
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* Updates the hash if the on flag is true and then writes the bytes
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* to the underlying output stream.
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*
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* @param b Bytes to write to the output stream
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* @param off Offset to start to start at in array
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* @param len Length of data to write
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*
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* @exception IOException if the underlying output stream
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* cannot write the bytes, this is thrown.
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*/
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public void write(byte[]b, int off, int len) throws IOException
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{
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if (state)
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digest.update(b, off, len);
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out.write(b, off, len);
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}
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/**
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* Sets the flag specifying if this DigestOutputStream updates the
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* digest in the write() methods. The default is on;
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*
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* @param on True means it digests stream, false means it does not
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*/
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public void on(boolean on)
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{
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state = on;
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}
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/**
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* Converts the output stream and underlying message digest to a string.
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*
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* @return A string representing the output stream and message digest.
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*/
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public String toString()
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{
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return "[Digest Output Stream] " + digest.toString();
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}
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}
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