updater/src/ie/wombat/jbdiff/JBPatch.java

/*
* Copyright (c) 2005, Joe Desbonnet, (jdesbonnet@gmail.com)
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*     * Redistributions of source code must retain the above copyright
*       notice, this list of conditions and the following disclaimer.
*     * 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.
*     * Neither the name of the <organization> nor the
*       names of its contributors may be used to endorse or promote products
*       derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY <copyright holder> ``AS IS'' AND ANY
* EXPRESS 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 <copyright holder> 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 ie.wombat.jbdiff;

import com.intellij.updater.Utils;

import java.io.*;
import java.util.zip.GZIPInputStream;

/**
 * Java Binary patcher (based on bspatch by Colin Percival)
 *
 * @author Joe Desbonnet, jdesbonnet@gmail.com
 */
public class JBPatch {
  public static void bspatch(InputStream oldFileIn, OutputStream newFileOut, InputStream diffFileIn)
    throws IOException {

    int oldpos, newpos;

    byte[] diffData = Utils.readBytes(diffFileIn);

    DataInputStream diffIn = new DataInputStream(new ByteArrayInputStream(diffData));

    // headerMagic at header offset 0 (length 8 bytes)
    long headerMagic = diffIn.readLong();

    // ctrlBlockLen after gzip compression at heater offset 8 (length 8 bytes)
    long ctrlBlockLen = diffIn.readLong();

    // diffBlockLen after gzip compression at header offset 16 (length 8 bytes)
    long diffBlockLen = diffIn.readLong();

    // size of new file at header offset 24 (length 8 bytes)
    int newsize = (int)diffIn.readLong();

    /*
                System.err.println ("newsize=" + newsize);
                System.err.println ("ctrlBlockLen=" + ctrlBlockLen);
                System.err.println ("diffBlockLen=" + diffBlockLen);
                System.err.println ("newsize=" + newsize);
                */

    InputStream in;
    in = new ByteArrayInputStream(diffData);
    in.skip(ctrlBlockLen + 32);
    GZIPInputStream diffBlockIn = new GZIPInputStream(in);

    in = new ByteArrayInputStream(diffData);
    in.skip(diffBlockLen + ctrlBlockLen + 32);
    GZIPInputStream extraBlockIn = new GZIPInputStream(in);

    /*
                 * Read in old file (file to be patched) to oldBuf
                 */
    ByteArrayOutputStream oldFileByteOut = new ByteArrayOutputStream();
    try {
      Utils.copyStream(oldFileIn, oldFileByteOut);
    }
    finally {
      oldFileByteOut.close();
    }
    byte[] oldBuf = oldFileByteOut.toByteArray();
    int oldsize = oldBuf.length;

    byte[] newBuf = new byte[newsize + 1];

    oldpos = 0;
    newpos = 0;
    int[] ctrl = new int[3];
    int nbytes;
    while (newpos < newsize) {

      for (int i = 0; i <= 2; i++) {
        ctrl[i] = diffIn.readInt();
        //System.err.println ("  ctrl[" + i + "]=" + ctrl[i]);
      }

      if (newpos + ctrl[0] > newsize) {
        System.err.println("Corrupt patch\n");
        return;
      }

      /*
                         * Read ctrl[0] bytes from diffBlock stream
                         */

      if (!Util.readFromStream(diffBlockIn, newBuf, newpos, ctrl[0])) {
        System.err.println("error reading from extraIn");
        return;
      }

      for (int i = 0; i < ctrl[0]; i++) {
        if ((oldpos + i >= 0) && (oldpos + i < oldsize)) {
          newBuf[newpos + i] += oldBuf[oldpos + i];
        }
      }

      newpos += ctrl[0];
      oldpos += ctrl[0];

      if (newpos + ctrl[1] > newsize) {
        System.err.println("Corrupt patch");
        return;
      }

      if (!Util.readFromStream(extraBlockIn, newBuf, newpos, ctrl[1])) {
        System.err.println("error reading from extraIn");
        return;
      }

      newpos += ctrl[1];
      oldpos += ctrl[2];
    }

    // TODO: Check if at end of ctrlIn
    // TODO: Check if at the end of diffIn
    // TODO: Check if at the end of extraIn

    diffBlockIn.close();
    extraBlockIn.close();
    diffIn.close();

    newFileOut.write(newBuf, 0, newBuf.length - 1);
  }
}