CascadeTransformer.java

/* CascadeTransformer.java -- 
   Copyright (C) 2003, 2006 Free Software Foundation, Inc.

This file is a 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 of the License, 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; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, 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
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permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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package gnu.javax.crypto.assembly;

import java.security.InvalidKeyException;
import java.util.Map;

/**
 * An Adapter to use any {@link Cascade} as a {@link Transformer} in an
 * {@link Assembly}.
 */
class CascadeTransformer
    extends Transformer
{
  private Cascade delegate;

  private int blockSize;

  CascadeTransformer(Cascade delegate)
  {
    super();

    this.delegate = delegate;
  }

  void initDelegate(Map attributes) throws TransformerException
  {
    attributes.put(Cascade.DIRECTION, wired);
    try
      {
        delegate.init(attributes);
      }
    catch (InvalidKeyException x)
      {
        throw new TransformerException("initDelegate()", x);
      }
    blockSize = delegate.currentBlockSize();
  }

  int delegateBlockSize()
  {
    return blockSize;
  }

  void resetDelegate()
  {
    delegate.reset();
    blockSize = 0;
  }

  byte[] updateDelegate(byte[] in, int offset, int length)
      throws TransformerException
  {
    byte[] result = updateInternal(in, offset, length);
    return result;
  }

  byte[] lastUpdateDelegate() throws TransformerException
  {
    if (inBuffer.size() != 0)
      {
        IllegalStateException cause = new IllegalStateException(
            "Cascade transformer, after last update, must be empty but isn't");
        throw new TransformerException("lastUpdateDelegate()", cause);
      }
    return new byte[0];
  }

  private byte[] updateInternal(byte[] in, int offset, int length)
  {
    byte[] result;
    for (int i = 0; i < length; i++)
      {
        inBuffer.write(in[offset++] & 0xFF);
        if (inBuffer.size() >= blockSize)
          {
            result = inBuffer.toByteArray();
            inBuffer.reset();
            delegate.update(result, 0, result, 0);
            outBuffer.write(result, 0, blockSize);
          }
      }
    result = outBuffer.toByteArray();
    outBuffer.reset();
    return result;
  }
}