com.sshtools.common.zlib.ZLibCompression Maven / Gradle / Ivy

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/**
 * (c) 2002-2021 JADAPTIVE Limited. All Rights Reserved.
 *
 * This file is part of the Maverick Synergy Java SSH API.
 *
 * Maverick Synergy is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Maverick Synergy 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with Maverick Synergy.  If not, see .
 */
package com.sshtools.common.zlib;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

import com.jcraft.jzlib.JZlib;
import com.jcraft.jzlib.ZStream;
import com.sshtools.common.ssh.compression.SshCompression;

@SuppressWarnings("deprecation")
public class ZLibCompression
   implements SshCompression {

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

  public String getAlgorithm() {
    return "zlib";
  }

  static private final int BUF_SIZE = 65535;

  ByteArrayOutputStream compressOut = new ByteArrayOutputStream(BUF_SIZE);
  ByteArrayOutputStream uncompressOut = new ByteArrayOutputStream(BUF_SIZE);

//  private int type;
  private ZStream stream;

  private byte[] inflated_buf = new byte[BUF_SIZE];
  private byte[] tmpbuf = new byte[BUF_SIZE];

  public void init(int type, int level) {
    if(type == SshCompression.DEFLATER) {
      stream.deflateInit(level);
//      this.type = SshCompression.DEFLATER;
    }
    else if(type == SshCompression.INFLATER) {
      stream.inflateInit();
//      this.type = SshCompression.INFLATER;
    }
  }


  public byte[] compress(byte[] buf, int start, int len) throws IOException {

    compressOut.reset();
    stream.next_in = buf;
    stream.next_in_index = start;
    stream.avail_in = len - start;
    int status;

    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:
          compressOut.write(tmpbuf, 0, BUF_SIZE - stream.avail_out);
          break;
        default:
          throw new IOException("compress: deflate returnd " + status);
      }
    }
    while(stream.avail_out == 0);

    return compressOut.toByteArray();
  }

  public byte[] uncompress(byte[] buffer, int start, int length) throws IOException {

//    int inflated_end = 0;
    uncompressOut.reset();

    stream.next_in = buffer;
    stream.next_in_index = start;
    stream.avail_in = length;

    while(true) {
      stream.next_out = inflated_buf;
      stream.next_out_index = 0;
      stream.avail_out = BUF_SIZE;
      int status = stream.inflate(JZlib.Z_PARTIAL_FLUSH);
      switch(status) {
        case JZlib.Z_OK:
          uncompressOut.write(inflated_buf, 0, BUF_SIZE - stream.avail_out);
          break;
        case JZlib.Z_BUF_ERROR:
          return uncompressOut.toByteArray();
        default:
          throw new IOException("uncompress: inflate returnd " + status);
      }
    }
  }

}