Initial revision

From-SVN: r102074

libjava/classpath/java/security/DigestInputStream.java

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+/* DigestInputStream.java --- An Input stream tied to a message digest
+   Copyright (C) 1999, 2003, 2004, 2005  Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package java.security;
+
+import java.io.FilterInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * DigestInputStream is a class that ties an InputStream with a 
+ * MessageDigest. The Message Digest is used by the class to 
+ * update it self as bytes are read from the InputStream.
+ *
+ * The updating to the digest depends on the on flag which is set
+ * to true by default to tell the class to update the data
+ * in the message digest.
+ *
+ * @version 0.0
+ * @author Mark Benvenuto (ivymccough@worldnet.att.net)
+ */
+public class DigestInputStream extends FilterInputStream
+{
+  /**
+   * The message digest for the DigestInputStream 
+   */
+  protected MessageDigest digest;
+
+  //Manages the on flag
+  private boolean state = true;
+
+  /**
+   * Constructs a new DigestInputStream.
+   * It associates a MessageDigest with the stream to 
+   * compute the stream as data is written.
+   *
+   * @param stream An InputStream to associate this stream with
+   * @param digest A MessageDigest to hash the stream with
+   */
+  public DigestInputStream(InputStream stream, MessageDigest digest)
+  {
+    super(stream);
+    //this.in = stream;
+    this.digest = digest;
+  }
+
+  /**
+   * Returns the MessageDigest associated with this DigestInputStream 
+   *
+   * @return The MessageDigest used to hash this stream
+   */
+  public MessageDigest getMessageDigest()
+  {
+    return digest;
+  }
+
+  /**
+   * Sets the current MessageDigest to current parameter
+   *
+   * @param digest A MessageDigest to associate with this stream
+   */
+  public void setMessageDigest(MessageDigest digest)
+  {
+    this.digest = digest;
+  }
+
+  /** 
+   * Reads a byte from the input stream and updates the digest.
+   * This method reads the underlying input stream and if the 
+   * on flag is true then updates the message digest.
+   *
+   * @return Returns a byte from the input stream, -1 is returned to indicate that 
+   * the end of stream was reached before this read call
+   *
+   * @throws IOException if an IO error occurs in the underlying input stream,
+   * this error is thrown
+   */
+  public int read() throws IOException
+  {
+    int temp = in.read();
+
+    if (state == true && temp != -1)
+      digest.update((byte) temp);
+
+    return temp;
+  }
+
+  /** 
+   * Reads bytes from the input stream and updates the digest.
+   * This method reads the underlying input stream and if the 
+   * on flag is true then updates the message digest.
+   *
+   * @param b a byte array to store the data from the input stream
+   * @param off an offset to start at in the array
+   * @param len length of data to read
+   * @return Returns count of bytes read, -1 is returned to indicate that 
+   * the end of stream was reached before this read call
+   *
+   * @throws IOException if an IO error occurs in the underlying input stream,
+   * this error is thrown
+   */
+  public int read(byte[]b, int off, int len) throws IOException
+  {
+    int temp = in.read(b, off, len);
+
+    if (state == true && temp != -1)
+      digest.update(b, off, temp);
+
+    return temp;
+  }
+
+  /**
+   * Sets the flag specifing if this DigestInputStream updates the
+   * digest in the write() methods. The default is on;
+   *
+   * @param on True means it digests stream, false means it does not
+   */
+  public void on(boolean on)
+  {
+    state = on;
+  }
+
+  /**
+   * Converts the input stream and underlying message digest to a string.
+   *
+   * @return A string representing the input stream and message digest.
+   */
+  public String toString()
+  {
+    return "[Digest Input Stream] " + digest.toString();
+  }
+}