mitm.common.util.MiscArrayUtils.java Source code

Introduction

Here is the source code for mitm.common.util.MiscArrayUtils.java

Source

/*
 * Copyright (c) 2008-2011, Martijn Brinkers, Djigzo.
 * 
 * This file is part of Djigzo email encryption.
 *
 * Djigzo is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License 
 * version 3, 19 November 2007 as published by the Free Software 
 * Foundation.
 *
 * Djigzo 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public 
 * License along with Djigzo. If not, see <http://www.gnu.org/licenses/>
 *
 * Additional permission under GNU AGPL version 3 section 7
 * 
 * If you modify this Program, or any covered work, by linking or 
 * combining it with aspectjrt.jar, aspectjweaver.jar, tyrex-1.0.3.jar, 
 * freemarker.jar, dom4j.jar, mx4j-jmx.jar, mx4j-tools.jar, 
 * spice-classman-1.0.jar, spice-loggerstore-0.5.jar, spice-salt-0.8.jar, 
 * spice-xmlpolicy-1.0.jar, saaj-api-1.3.jar, saaj-impl-1.3.jar, 
 * wsdl4j-1.6.1.jar (or modified versions of these libraries), 
 * containing parts covered by the terms of Eclipse Public License, 
 * tyrex license, freemarker license, dom4j license, mx4j license,
 * Spice Software License, Common Development and Distribution License
 * (CDDL), Common Public License (CPL) the licensors of this Program grant 
 * you additional permission to convey the resulting work.
 */
package mitm.common.util;

import java.math.BigInteger;

import org.apache.commons.lang.ArrayUtils;

/**
 * Array utility functions.
 * 
 * @author Martijn Brinkers
 *
 */
public class MiscArrayUtils {
    /**
     * Compares the two arrays. If the sizes are different it is assumed that the shortest array
     * is padded with 0's.
     * @param a
     * @param b
     * @return
     */
    public static int compareArray(byte[] a, byte[] b) {
        if (a.length < b.length) {
            for (int i = 0; i != a.length; i++) {
                int l = a[i] & 0xff;
                int r = b[i] & 0xff;

                if (r > l) {
                    return -1;
                } else if (l > r) {
                    return 1;
                }
            }

            return -1;
        } else if (a.length > b.length) {
            for (int i = 0; i != b.length; i++) {
                int l = a[i] & 0xff;
                int r = b[i] & 0xff;

                if (r > l) {
                    return -1;
                } else if (l > r) {
                    return 1;
                }
            }

            return 1;
        } else {
            for (int i = 0; i != b.length; i++) {
                int l = a[i] & 0xff;
                int r = b[i] & 0xff;

                if (r > l) {
                    return -1;
                } else if (l > r) {
                    return 1;
                }
            }

            return 0;
        }
    }

    /**
     * Encodes the byte array to a String consisting of all readable characters.
     */
    public static String toMaxRadix(byte[] bytes) {
        Check.notNull(bytes, "bytes");

        /*
         * We need to make sure that the BigInteger will be positive and that any starting zero (0) bytes
         * are not removed.
         */
        byte[] pos = ArrayUtils.addAll(new byte[] { 1 }, bytes);

        BigInteger bigInt = new BigInteger(pos);

        return bigInt.toString(Character.MAX_RADIX);
    }

    /**
     * Converts the input string which is encoded in MAX_RADIX to a byte array (this function 
     * is the complement of ArrayUtils#toMaxRadix) 
     */
    public static byte[] fromMaxRadix(String inputMaxRadix) {
        Check.notNull(inputMaxRadix, "inputMaxRadix");

        BigInteger bigInt = new BigInteger(inputMaxRadix, Character.MAX_RADIX);

        byte[] bytes = bigInt.toByteArray();

        /*
         * We need to remove the first byte added by toMaxRadix.
         */
        return ArrayUtils.subarray(bytes, 1, bytes.length);
    }

    /**
     * Clears the byte array (can be used for example to clear out passwords)
     */
    public static char[] clear(char[] array) {
        if (array != null) {
            for (int i = 0; i < array.length; i++) {
                array[i] = 0;
            }
        }

        return array;
    }

    /**
     * Returns the object at the given index. If the index is out of bounds null will be returned.
     */
    public static <T> T safeGet(T[] array, int index) {
        if (array == null) {
            return null;
        }

        if (index < 0 || index > array.length - 1) {
            return null;
        }

        return array[index];
    }
}