Compression.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
/* -*-mode:java; c-basic-offset:2; indent-tabs-mode:nil -*- */
/*
Copyright (c) 2002-2008 ymnk, JCraft,Inc. All rights reserved.

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.apache.sshd.util;

import com.jcraft.jzlib.JZlib;
import com.jcraft.jzlib.ZStream;

/**
 * TODO Add javadoc
 *
 * @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a>
 */
public class Compression implements com.jcraft.jsch.Compression {
  static private final int BUF_SIZE=4096;

  private int type;
  private ZStream stream;
  private byte[] tmpbuf=new byte[BUF_SIZE];

  public Compression(){
    stream=new ZStream();
  }

  public void init(int type, int level){
    if(type==DEFLATER){
      stream.deflateInit(level);
      this.type=DEFLATER;
    }
    else if(type==INFLATER){
      stream.inflateInit();
      inflated_buf=new byte[BUF_SIZE];
      this.type=INFLATER;
    }
  }
  /*
  static Compression getDeflater(int level){
    Compression foo=new Compression();
    foo.stream.deflateInit(level);
    foo.type=DEFLATER;
    return foo;
  }
  */
  private byte[] inflated_buf;
  /*
  static Compression getInflater(){
    Compression foo=new Compression();
    foo.stream.inflateInit();
    foo.inflated_buf=new byte[BUF_SIZE];
    foo.type=INFLATER;
    return foo;
  }
  */

  public int compress(byte[] buf, int start, int len){
    stream.next_in=buf;
    stream.next_in_index=start;
    stream.avail_in=len-start;
    int status;
    int outputlen=start;

    do{
      stream.next_out=tmpbuf;
      stream.next_out_index=0;
      stream.avail_out=BUF_SIZE;
      status=stream.deflate(JZlib.Z_PARTIAL_FLUSH);
      switch(status){
        case JZlib.Z_OK:
	    System.arraycopy(tmpbuf, 0,
			     buf, outputlen,
			     BUF_SIZE-stream.avail_out);
	    outputlen+=(BUF_SIZE-stream.avail_out);
	    break;
        default:
	    System.err.println("compress: deflate returnd "+status);
      }
    }
    while(stream.avail_out==0);
    return outputlen;
  }

  public byte[] uncompress(byte[] buffer, int start, int[] length){
    int inflated_end=0;

    stream.next_in=buffer;
    stream.next_in_index=start;
    stream.avail_in=length[0];

    while(true){
      stream.next_out=tmpbuf;
      stream.next_out_index=0;
      stream.avail_out=BUF_SIZE;
      int status=stream.inflate(JZlib.Z_PARTIAL_FLUSH);
      switch(status){
        case JZlib.Z_OK:
	  if(inflated_buf.length<inflated_end+BUF_SIZE-stream.avail_out){
            byte[] foo=new byte[inflated_end+BUF_SIZE-stream.avail_out];
	    System.arraycopy(inflated_buf, 0, foo, 0, inflated_end);
	    inflated_buf=foo;
	  }
	  System.arraycopy(tmpbuf, 0,
			   inflated_buf, inflated_end,
			   BUF_SIZE-stream.avail_out);
	  inflated_end+=(BUF_SIZE-stream.avail_out);
          length[0]=inflated_end;
	  break;
        case JZlib.Z_BUF_ERROR:
          if(inflated_end>buffer.length-start){
            byte[] foo=new byte[inflated_end+start];
            System.arraycopy(buffer, 0, foo, 0, start);
            System.arraycopy(inflated_buf, 0, foo, start, inflated_end);
	    buffer=foo;
	  }
	  else{
            System.arraycopy(inflated_buf, 0, buffer, start, inflated_end);
	  }
          length[0]=inflated_end;
	  return buffer;
	default:
	  System.err.println("uncompress: inflate returnd "+status);
          return null;
      }
    }
  }
}