    001/*
    002 *  Licensed to the Apache Software Foundation (ASF) under one or more
    003 *  contributor license agreements.  See the NOTICE file distributed with
    004 *  this work for additional information regarding copyright ownership.
    005 *  The ASF licenses this file to You under the Apache License, Version 2.0
    006 *  (the "License"); you may not use this file except in compliance with
    007 *  the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 *  Unless required by applicable law or agreed to in writing, software
    012 *  distributed under the License is distributed on an "AS IS" BASIS,
    013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 *  See the License for the specific language governing permissions and
    015 *  limitations under the License.
    016 */
    017package org.apache.commons.compress.archivers.zip;
    018
    019import static org.apache.commons.compress.archivers.zip.ZipConstants.BYTE_MASK;
    020
    021import java.io.Serializable;
    022import java.math.BigInteger;
    023
    024/**
    025 * Utility class that represents an eight byte integer with conversion rules for the little-endian byte order of ZIP files.
    026 *
    027 * @Immutable
    028 *
    029 * @since 1.2
    030 */
    031public final class ZipEightByteInteger implements Serializable {
    032    private static final long serialVersionUID = 1L;
    033
    034    private static final int BYTE_1 = 1;
    035    private static final int BYTE_1_MASK = 0xFF00;
    036    private static final int BYTE_1_SHIFT = 8;
    037
    038    private static final int BYTE_2 = 2;
    039    private static final int BYTE_2_MASK = 0xFF0000;
    040    private static final int BYTE_2_SHIFT = 16;
    041
    042    private static final int BYTE_3 = 3;
    043    private static final long BYTE_3_MASK = 0xFF000000L;
    044    private static final int BYTE_3_SHIFT = 24;
    045
    046    private static final int BYTE_4 = 4;
    047    private static final long BYTE_4_MASK = 0xFF00000000L;
    048    private static final int BYTE_4_SHIFT = 32;
    049
    050    private static final int BYTE_5 = 5;
    051    private static final long BYTE_5_MASK = 0xFF0000000000L;
    052    private static final int BYTE_5_SHIFT = 40;
    053
    054    private static final int BYTE_6 = 6;
    055    private static final long BYTE_6_MASK = 0xFF000000000000L;
    056    private static final int BYTE_6_SHIFT = 48;
    057
    058    private static final int BYTE_7 = 7;
    059    private static final long BYTE_7_MASK = 0x7F00000000000000L;
    060    private static final int BYTE_7_SHIFT = 56;
    061
    062    private static final int LEFTMOST_BIT_SHIFT = 63;
    063    private static final byte LEFTMOST_BIT = (byte) 0x80;
    064
    065    public static final ZipEightByteInteger ZERO = new ZipEightByteInteger(0);
    066
    067    /**
    068     * Gets value as eight bytes in big-endian byte order.
    069     *
    070     * @param value the value to convert
    071     * @return value as eight bytes in big-endian byte order
    072     */
    073    public static byte[] getBytes(final BigInteger value) {
    074        final byte[] result = new byte[8];
    075        final long val = value.longValue();
    076        result[0] = (byte) (val & BYTE_MASK);
    077        result[BYTE_1] = (byte) ((val & BYTE_1_MASK) >> BYTE_1_SHIFT);
    078        result[BYTE_2] = (byte) ((val & BYTE_2_MASK) >> BYTE_2_SHIFT);
    079        result[BYTE_3] = (byte) ((val & BYTE_3_MASK) >> BYTE_3_SHIFT);
    080        result[BYTE_4] = (byte) ((val & BYTE_4_MASK) >> BYTE_4_SHIFT);
    081        result[BYTE_5] = (byte) ((val & BYTE_5_MASK) >> BYTE_5_SHIFT);
    082        result[BYTE_6] = (byte) ((val & BYTE_6_MASK) >> BYTE_6_SHIFT);
    083        result[BYTE_7] = (byte) ((val & BYTE_7_MASK) >> BYTE_7_SHIFT);
    084        if (value.testBit(LEFTMOST_BIT_SHIFT)) {
    085            result[BYTE_7] |= LEFTMOST_BIT;
    086        }
    087        return result;
    088    }
    089
    090    /**
    091     * Gets value as eight bytes in big-endian byte order.
    092     *
    093     * @param value the value to convert
    094     * @return value as eight bytes in big-endian byte order
    095     */
    096    public static byte[] getBytes(final long value) {
    097        return getBytes(BigInteger.valueOf(value));
    098    }
    099
    100    /**
    101     * Helper method to get the value as a Java long from an eight-byte array
    102     *
    103     * @param bytes the array of bytes
    104     * @return the corresponding Java long value
    105     */
    106    public static long getLongValue(final byte[] bytes) {
    107        return getLongValue(bytes, 0);
    108    }
    109
    110    /**
    111     * Helper method to get the value as a Java long from eight bytes starting at given array offset
    112     *
    113     * @param bytes  the array of bytes
    114     * @param offset the offset to start
    115     * @return the corresponding Java long value
    116     */
    117    public static long getLongValue(final byte[] bytes, final int offset) {
    118        return getValue(bytes, offset).longValue();
    119    }
    120
    121    /**
    122     * Helper method to get the value as a Java long from an eight-byte array
    123     *
    124     * @param bytes the array of bytes
    125     * @return the corresponding Java BigInteger value
    126     */
    127    public static BigInteger getValue(final byte[] bytes) {
    128        return getValue(bytes, 0);
    129    }
    130
    131    /**
    132     * Helper method to get the value as a Java BigInteger from eight bytes starting at given array offset
    133     *
    134     * @param bytes  the array of bytes
    135     * @param offset the offset to start
    136     * @return the corresponding Java BigInteger value
    137     */
    138    public static BigInteger getValue(final byte[] bytes, final int offset) {
    139        long value = (long) bytes[offset + BYTE_7] << BYTE_7_SHIFT & BYTE_7_MASK;
    140        value += (long) bytes[offset + BYTE_6] << BYTE_6_SHIFT & BYTE_6_MASK;
    141        value += (long) bytes[offset + BYTE_5] << BYTE_5_SHIFT & BYTE_5_MASK;
    142        value += (long) bytes[offset + BYTE_4] << BYTE_4_SHIFT & BYTE_4_MASK;
    143        value += (long) bytes[offset + BYTE_3] << BYTE_3_SHIFT & BYTE_3_MASK;
    144        value += (long) bytes[offset + BYTE_2] << BYTE_2_SHIFT & BYTE_2_MASK;
    145        value += (long) bytes[offset + BYTE_1] << BYTE_1_SHIFT & BYTE_1_MASK;
    146        value += (long) bytes[offset] & BYTE_MASK;
    147        final BigInteger val = BigInteger.valueOf(value);
    148        return (bytes[offset + BYTE_7] & LEFTMOST_BIT) == LEFTMOST_BIT ? val.setBit(LEFTMOST_BIT_SHIFT) : val;
    149    }
    150
    151    private final BigInteger value;
    152
    153    /**
    154     * Constructs a new instance from a number.
    155     *
    156     * @param value the BigInteger to store as a ZipEightByteInteger
    157     */
    158    public ZipEightByteInteger(final BigInteger value) {
    159        this.value = value;
    160    }
    161
    162    /**
    163     * Constructs a new instance from bytes.
    164     *
    165     * @param bytes the bytes to store as a ZipEightByteInteger
    166     */
    167    public ZipEightByteInteger(final byte[] bytes) {
    168        this(bytes, 0);
    169    }
    170
    171    /**
    172     * Constructs a new instance from the eight bytes starting at offset.
    173     *
    174     * @param bytes  the bytes to store as a ZipEightByteInteger
    175     * @param offset the offset to start
    176     */
    177    public ZipEightByteInteger(final byte[] bytes, final int offset) {
    178        value = ZipEightByteInteger.getValue(bytes, offset);
    179    }
    180
    181    /**
    182     * Constructs a new instance from a number.
    183     *
    184     * @param value the long to store as a ZipEightByteInteger
    185     */
    186    public ZipEightByteInteger(final long value) {
    187        this(BigInteger.valueOf(value));
    188    }
    189
    190    /**
    191     * Override to make two instances with same value equal.
    192     *
    193     * @param o an object to compare
    194     * @return true if the objects are equal
    195     */
    196    @Override
    197    public boolean equals(final Object o) {
    198        if (!(o instanceof ZipEightByteInteger)) {
    199            return false;
    200        }
    201        return value.equals(((ZipEightByteInteger) o).getValue());
    202    }
    203
    204    /**
    205     * Gets value as eight bytes in big-endian byte order.
    206     *
    207     * @return value as eight bytes in big-endian order
    208     */
    209    public byte[] getBytes() {
    210        return ZipEightByteInteger.getBytes(value);
    211    }
    212
    213    /**
    214     * Gets value as Java long.
    215     *
    216     * @return value as a long
    217     */
    218    public long getLongValue() {
    219        return value.longValue();
    220    }
    221
    222    /**
    223     * Gets value as Java BigInteger.
    224     *
    225     * @return value as a BigInteger
    226     */
    227    public BigInteger getValue() {
    228        return value;
    229    }
    230
    231    /**
    232     * Override to make two instances with same value equal.
    233     *
    234     * @return the hash code of the value stored in the ZipEightByteInteger
    235     */
    236    @Override
    237    public int hashCode() {
    238        return value.hashCode();
    239    }
    240
    241    @Override
    242    public String toString() {
    243        return "ZipEightByteInteger value: " + value;
    244    }
    245}