1 /*

     2  * Copyright (c) 1998, 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.

     8  *

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

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

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

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

    13  * accompanied this code).

    14  *

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

    16  * 2 along with this work; if not, write to the Free Software Foundation,

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

    18  *

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

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

    21  * questions.

    22  */

    23 

    24 /* @test

    25    @bug 4098742

    26    @summary Test biginteger modpow method

    27    @author Michael McCloskey

    28    @run main/othervm ModPowPowersof2

    29 */

    30 

    31 import java.math.BigInteger;

    32 import java.io.BufferedReader;

    33 import java.io.InputStreamReader;

    34 import java.io.File;

    35 import java.io.IOException;

    36 

    37 /**

    38  * This class tests to see if using modPow on a power

    39  * of two crashes the vm

    40  *

    41  */

    42 public class ModPowPowersof2 {

    43 

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

    45           // Construct a command that runs the test in other vm

    46           String[] command = new String[4];

    47           int n = 0;

    48 

    49           command[n++] = System.getProperty("java.home") + File.separator +

    50               "bin" + File.separator + "java";

    51           if (System.getProperty("java.class.path") != null) {

    52               command[n++] = "-classpath";

    53               command[n++] = System.getProperty("java.class.path");

    54           }

    55 

    56           command[n++] = "ModPowPowersof2$ModTester";

    57 

    58           // Exec another vm to run test in

    59           Process p = null;

    60           p = Runtime.getRuntime().exec(command);

    61 

    62           // Read the result to determine if test failed

    63           BufferedReader in = new BufferedReader(new InputStreamReader(

    64                                              p.getInputStream()));

    65           String s;

    66           s = in.readLine();

    67           if (s == null)

    68               throw new RuntimeException("ModPow causes vm crash");

    69 

    70      }

    71 

    72     public static class ModTester {

    73         public static void main(String [] args) {

    74             BigInteger two = BigInteger.valueOf(2);

    75             BigInteger four = BigInteger.valueOf(4);

    76 

    77             two.modPow(two, BigInteger.valueOf(4));

    78             two.modPow(two, BigInteger.valueOf(8));

    79             two.modPow(four, BigInteger.valueOf(8));

    80 

    81             System.out.println("success");

    82         }

    83     }

    84 

    85 }