/*
* Copyright (c) 2002-2010 Atsuhiko Yamanaka, JCraft,Inc. All rights reserved.
* Copyright (c) 2010-2011 Michael Laudati, N1 Concepts LLC.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The names of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
* INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.vngx.jsch.algorithm;
import com.jcraft.jzlib.JZlib;
import com.jcraft.jzlib.ZStream;
/**
* <p>Implementation of {@code Compression} which uses the JCraft jzlib library
* to compress and/or uncompress byte data.</p>
*
* <p><strong>Note:</strong> This class is not thread-safe and must be
* externally synchronized.</p>
*
* @see com.jcraft.jzlib.JZlib
* @see com.jcraft.jzlib.ZStream
* @see org.vngx.jsch.Compression
*
* @author Atsuhiko Yamanaka
* @author Michael Laudati
*/
public final class CompressionImpl implements Compression {
/** Constant buffer size to use when compressing/decompressing. */
private static final int BUF_SIZE = 4096;
/** JZlib stream used for inflating/deflating session data. */
private final ZStream _zstream;
/** Buffer used when inflating. */
private byte[] _inflatedBuffer;
/** Temporary buffer used for performance. */
private final byte[] _tmp = new byte[BUF_SIZE];
/**
* Creates a new instance of {@code Compression}.
*/
public CompressionImpl() {
_zstream = new ZStream();
}
@Override
public void init(int type, int level) {
switch( type ) {
case COMPRESS_MODE:
_zstream.deflateInit(level);
break;
case DECOMPRESS_MODE:
_zstream.inflateInit();
_inflatedBuffer = new byte[BUF_SIZE];
break;
default:
throw new IllegalArgumentException("Invalid compression type: "+type);
}
}
@Override
public int compress(byte[] buffer, int offset, int length) {
_zstream.next_in = buffer;
_zstream.next_in_index = offset;
_zstream.avail_in = length - offset;
int status, outputLen = offset;
do {
_zstream.next_out = _tmp;
_zstream.next_out_index = 0;
_zstream.avail_out = BUF_SIZE;
status = _zstream.deflate(JZlib.Z_PARTIAL_FLUSH);
switch( status ) {
case JZlib.Z_OK:
System.arraycopy(_tmp, 0, buffer, outputLen, BUF_SIZE - _zstream.avail_out);
outputLen += (BUF_SIZE - _zstream.avail_out);
break;
default:
// TODO Error handling?
System.err.println("compress: deflate returned " + status);
}
} while( _zstream.avail_out == 0 );
return outputLen;
}
@Override
public byte[] uncompress(byte[] buffer, int offset, int[] length) {
int inflated_end = 0;
int status;
_zstream.next_in = buffer;
_zstream.next_in_index = offset;
_zstream.avail_in = length[0];
while( true ) {
_zstream.next_out = _tmp;
_zstream.next_out_index = 0;
_zstream.avail_out = BUF_SIZE;
status = _zstream.inflate(JZlib.Z_PARTIAL_FLUSH);
switch( status ) {
case JZlib.Z_OK:
if( _inflatedBuffer.length < inflated_end + BUF_SIZE - _zstream.avail_out ) {
byte[] foo = new byte[inflated_end + BUF_SIZE - _zstream.avail_out];
System.arraycopy(_inflatedBuffer, 0, foo, 0, inflated_end);
_inflatedBuffer = foo;
}
System.arraycopy(_tmp, 0, _inflatedBuffer, inflated_end, BUF_SIZE - _zstream.avail_out);
inflated_end += (BUF_SIZE - _zstream.avail_out);
length[0] = inflated_end;
break;
case JZlib.Z_BUF_ERROR:
if( inflated_end > buffer.length - offset ) {
byte[] foo = new byte[inflated_end + offset];
System.arraycopy(buffer, 0, foo, 0, offset);
System.arraycopy(_inflatedBuffer, 0, foo, offset, inflated_end);
buffer = foo;
} else {
System.arraycopy(_inflatedBuffer, 0, buffer, offset, inflated_end);
}
length[0] = inflated_end;
return buffer;
default:
// TODO Error handling?
System.err.println("uncompress: inflate returned " + status);
return null;
}
}
}
}