/*

 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package build.tools.addjsum;

import java.io.*;

import java.util.regex.*;

/** Adds a checksum ("jsum") to the end of a text file. The algorithm

    used is known to the JVM and prevents trivial tampering with the

    class list used for class data sharing.

*/

public class AddJsum {

  private static final long JSUM_SEED = 0xCAFEBABEBABECAFEL;

  public static void main(String[] args) throws Exception {

    if (args.length != 2) {

      System.err.println("Usage: java AddJsum [input file name] [output file name]");

      System.exit(1);

    }

    try {

      File inFile  = new File(args[0]);

      File outFile = new File(args[1]);

      BufferedReader reader = new BufferedReader(new FileReader(inFile));

      BufferedWriter writer = new BufferedWriter(new FileWriter(outFile));

      Pattern p = Pattern.compile("# [0-9A-Fa-f]*");

      long computedJsum = JSUM_SEED;

      String line = null;

      while ((line = reader.readLine()) != null) {

        if (line.length() > 0 && line.charAt(0) == '#') {

          Matcher m = p.matcher(line);

          if (!m.matches()) {

            writer.write(line);

            writer.newLine();

          }

        } else {

          computedJsum = jsum(computedJsum, line);

          writer.write(line);

          writer.newLine();

        }

      }

      String hex = Long.toHexString(computedJsum);

      int diff = 16 - hex.length();

      for (int i = 0; i < diff; i++) {

        hex = "0" + hex;

      }

      writer.write("# " + hex);

      writer.newLine();

      reader.close();

      writer.close();

    } catch (IOException e) {

      System.err.println("Error reading or writing file");

      throw(e);

    }

  }

  private static long jsum(long start, String str) {

    long h = start;

    int len = str.length();

    for (int i = 0; i < len; i++) {

      char c = str.charAt(i);

      if (c <= ' ') {

        /* Skip spaces and control characters */

        continue;

      }

      h = 31 * h + c;

    }

    return h;

  }

}