package gnu.crypto.assembly;
// ----------------------------------------------------------------------------
// Id: $
//
// Copyright (C) 2003, Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto 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 Crypto 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 this program; 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.
// ----------------------------------------------------------------------------
import java.util.Map;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;
/**
* <p>A {@link Transformer} Adapter allowing inclusion of a DEFLATE compression
* algorithm in an {@link Assembly} chain. The {@link Direction#FORWARD}
* transformation is a compression (deflate) of input data, while the
* {@link Direction#REVERSED} one is a decompression (inflate) that restores
* the original data.</p>
*
* <p>This {@link Transformer} uses a {@link Deflater} instance to carry on the
* compression, and an {@link Inflater} to do the decompression.</p>
*
* <p>When using such a {@link Transformer}, in an {@link Assembly}, there must
* be at least one element behind this instance in the constructed chain;
* otherwise, a {@link TransformerException} is thrown at initialisation time.</p>
*
* @version Revision: $
*/
class DeflateTransformer extends Transformer {
// Constants and variables
// -------------------------------------------------------------------------
private Deflater compressor;
private Inflater decompressor;
private int outputBlockSize = 512; // default zlib buffer size
private byte[] zlibBuffer;
// Constructor(s)
// -------------------------------------------------------------------------
DeflateTransformer() {
super();
}
// Class methods
// -------------------------------------------------------------------------
// Instance methods
// -------------------------------------------------------------------------
void initDelegate(Map attributes) throws TransformerException {
if (tail == null) {
throw new TransformerException("initDelegate()",
new IllegalStateException("Compression transformer missing its tail!"));
}
outputBlockSize = tail.currentBlockSize();
zlibBuffer = new byte[outputBlockSize];
Direction flow = (Direction) attributes.get(DIRECTION);
if (flow == Direction.FORWARD) {
compressor = new Deflater();
} else {
decompressor = new Inflater();
}
}
int delegateBlockSize() {
// return outputBlockSize;
return 1;
}
void resetDelegate() {
compressor = null;
decompressor = null;
outputBlockSize = 1;
zlibBuffer = null;
}
byte[] updateDelegate(byte[] in, int offset, int length)
throws TransformerException {
byte[] result;
if (wired == Direction.FORWARD) {
compressor.setInput(in, offset, length);
while (!compressor.needsInput()) {
compress();
}
} else { // decompression: inflate first and then update tail
decompress(in, offset, length);
}
result = inBuffer.toByteArray();
inBuffer.reset();
return result;
}
// byte[] lastUpdateDelegate(byte[] in, int offset, int length)
// throws TransformerException {
// // process multiples of blocksize as much as possible
// byte[] result = this.updateDelegate(in, offset, length);
// inBuffer.write(result, 0, result.length);
// if (wired == Direction.FORWARD) { // compressing
// if (!compressor.finished()) {
// compressor.finish();
// while (!compressor.finished()) {
// compress();
// }
// }
// } else { // decompressing
// if (!decompressor.finished()) {
// throw new TransformerException("lastUpdateDelegate()",
// new IllegalStateException("Compression transformer, after last "
// +"update, must be finished but isn't"));
// }
// }
//
// result = inBuffer.toByteArray();
// inBuffer.reset();
// return result;
// }
byte[] lastUpdateDelegate()
throws TransformerException {
// process multiples of blocksize as much as possible
if (wired == Direction.FORWARD) { // compressing
if (!compressor.finished()) {
compressor.finish();
while (!compressor.finished()) {
compress();
}
}
} else { // decompressing
if (!decompressor.finished()) {
throw new TransformerException("lastUpdateDelegate()",
new IllegalStateException("Compression transformer, after last "
+"update, must be finished but isn't"));
}
}
byte[] result = inBuffer.toByteArray();
inBuffer.reset();
return result;
}
private void compress() {
int len = compressor.deflate(zlibBuffer);
if (len > 0) {
inBuffer.write(zlibBuffer, 0, len);
}
}
private void decompress(byte[] in, int offset, int length)
throws TransformerException {
decompressor.setInput(in, offset, length);
int len = 1;
while (len > 0) {
try {
len = decompressor.inflate(zlibBuffer);
} catch (DataFormatException x) {
throw new TransformerException("decompress()", x);
}
if (len > 0) {
inBuffer.write(zlibBuffer, 0, len);
}
}
}
}