1 /*

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

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

     4  *

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

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

     7  * published by the Free Software Foundation.  Oracle designates this

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

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

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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

    15  * accompanied this code).

    16  *

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

    18  * 2 along with this work; if not, write to the Free Software Foundation,

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

    20  *

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

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package build.tools.addjsum;

    27 

    28 import java.io.*;

    29 import java.util.regex.*;

    30 

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

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

    33     class list used for class data sharing.

    34 */

    35 

    36 public class AddJsum {

    37   private static final long JSUM_SEED = 0xCAFEBABEBABECAFEL;

    38 

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

    40     if (args.length != 2) {

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

    42       System.exit(1);

    43     }

    44 

    45     try {

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

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

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

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

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

    51       long computedJsum = JSUM_SEED;

    52 

    53       String line = null;

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

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

    56           Matcher m = p.matcher(line);

    57           if (!m.matches()) {

    58             writer.write(line);

    59             writer.newLine();

    60           }

    61         } else {

    62           computedJsum = jsum(computedJsum, line);

    63           writer.write(line);

    64           writer.newLine();

    65         }

    66       }

    67       String hex = Long.toHexString(computedJsum);

    68       int diff = 16 - hex.length();

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

    70         hex = "0" + hex;

    71       }

    72       writer.write("# " + hex);

    73       writer.newLine();

    74       reader.close();

    75       writer.close();

    76     } catch (IOException e) {

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

    78       throw(e);

    79     }

    80   }

    81 

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

    83     long h = start;

    84     int len = str.length();

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

    86       char c = str.charAt(i);

    87       if (c <= ' ') {

    88         /* Skip spaces and control characters */

    89         continue;

    90       }

    91       h = 31 * h + c;

    92     }

    93     return h;

    94   }

    95 }