author | chegar |
Sun, 17 Aug 2014 15:54:13 +0100 | |
changeset 25859 | 3317bb8137f4 |
parent 18579 | jdk/src/share/classes/java/security/DigestInputStream.java@b678846778ad |
child 40789 | 43b42538af90 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package java.security; |
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import java.io.IOException; |
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import java.io.EOFException; |
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import java.io.InputStream; |
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import java.io.FilterInputStream; |
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import java.io.PrintStream; |
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import java.io.ByteArrayInputStream; |
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/** |
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* A transparent stream that updates the associated message digest using |
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* the bits going through the stream. |
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* |
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* <p>To complete the message digest computation, call one of the |
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* {@code digest} methods on the associated message |
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* digest after your calls to one of this digest input stream's |
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* {@link #read() read} methods. |
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* |
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* <p>It is possible to turn this stream on or off (see |
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* {@link #on(boolean) on}). When it is on, a call to one of the |
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* {@code read} methods |
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* results in an update on the message digest. But when it is off, |
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* the message digest is not updated. The default is for the stream |
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* to be on. |
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* |
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* <p>Note that digest objects can compute only one digest (see |
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* {@link MessageDigest}), |
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* so that in order to compute intermediate digests, a caller should |
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* retain a handle onto the digest object, and clone it for each |
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* digest to be computed, leaving the orginal digest untouched. |
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* |
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* @see MessageDigest |
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* |
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* @see DigestOutputStream |
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* |
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* @author Benjamin Renaud |
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*/ |
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public class DigestInputStream extends FilterInputStream { |
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/* NOTE: This should be made a generic UpdaterInputStream */ |
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/* Are we on or off? */ |
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private boolean on = true; |
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/** |
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* The message digest associated with this stream. |
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*/ |
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protected MessageDigest digest; |
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/** |
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* Creates a digest input stream, using the specified input stream |
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* and message digest. |
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* |
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* @param stream the input stream. |
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* |
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* @param digest the message digest to associate with this stream. |
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*/ |
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public DigestInputStream(InputStream stream, MessageDigest digest) { |
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super(stream); |
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setMessageDigest(digest); |
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} |
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/** |
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* Returns the message digest associated with this stream. |
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* |
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* @return the message digest associated with this stream. |
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* @see #setMessageDigest(java.security.MessageDigest) |
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*/ |
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public MessageDigest getMessageDigest() { |
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return digest; |
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} |
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/** |
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* Associates the specified message digest with this stream. |
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* |
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* @param digest the message digest to be associated with this stream. |
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* @see #getMessageDigest() |
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*/ |
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public void setMessageDigest(MessageDigest digest) { |
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this.digest = digest; |
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} |
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/** |
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* Reads a byte, and updates the message digest (if the digest |
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* function is on). That is, this method reads a byte from the |
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* input stream, blocking until the byte is actually read. If the |
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* digest function is on (see {@link #on(boolean) on}), this method |
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* will then call {@code update} on the message digest associated |
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* with this stream, passing it the byte read. |
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* |
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* @return the byte read. |
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* |
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* @exception IOException if an I/O error occurs. |
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* |
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* @see MessageDigest#update(byte) |
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*/ |
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public int read() throws IOException { |
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int ch = in.read(); |
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if (on && ch != -1) { |
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digest.update((byte)ch); |
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} |
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return ch; |
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} |
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/** |
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* Reads into a byte array, and updates the message digest (if the |
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* digest function is on). That is, this method reads up to |
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* {@code len} bytes from the input stream into the array |
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* {@code b}, starting at offset {@code off}. This method |
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* blocks until the data is actually |
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* read. If the digest function is on (see |
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* {@link #on(boolean) on}), this method will then call {@code update} |
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* on the message digest associated with this stream, passing it |
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* the data. |
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* |
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* @param b the array into which the data is read. |
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* |
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* @param off the starting offset into {@code b} of where the |
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* data should be placed. |
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* |
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* @param len the maximum number of bytes to be read from the input |
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* stream into b, starting at offset {@code off}. |
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* |
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* @return the actual number of bytes read. This is less than |
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* {@code len} if the end of the stream is reached prior to |
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* reading {@code len} bytes. -1 is returned if no bytes were |
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* read because the end of the stream had already been reached when |
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* the call was made. |
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* |
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* @exception IOException if an I/O error occurs. |
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* |
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* @see MessageDigest#update(byte[], int, int) |
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*/ |
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public int read(byte[] b, int off, int len) throws IOException { |
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int result = in.read(b, off, len); |
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if (on && result != -1) { |
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digest.update(b, off, result); |
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} |
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return result; |
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} |
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/** |
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* Turns the digest function on or off. The default is on. When |
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* it is on, a call to one of the {@code read} methods results in an |
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* update on the message digest. But when it is off, the message |
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* digest is not updated. |
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* |
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* @param on true to turn the digest function on, false to turn |
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* it off. |
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*/ |
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public void on(boolean on) { |
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this.on = on; |
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} |
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/** |
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* Prints a string representation of this digest input stream and |
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* its associated message digest object. |
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*/ |
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public String toString() { |
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return "[Digest Input Stream] " + digest.toString(); |
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} |
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} |