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
026 * rules for the little endian byte order of ZIP files.
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     * Get value as eight bytes in big endian byte order.
069     * @param value the value to convert
070     * @return value as eight bytes in big endian byte order
071     */
072    public static byte[] getBytes(final BigInteger value) {
073        final byte[] result = new byte[8];
074        final long val = value.longValue();
075        result[0] = (byte) ((val & BYTE_MASK));
076        result[BYTE_1] = (byte) ((val & BYTE_1_MASK) >> BYTE_1_SHIFT);
077        result[BYTE_2] = (byte) ((val & BYTE_2_MASK) >> BYTE_2_SHIFT);
078        result[BYTE_3] = (byte) ((val & BYTE_3_MASK) >> BYTE_3_SHIFT);
079        result[BYTE_4] = (byte) ((val & BYTE_4_MASK) >> BYTE_4_SHIFT);
080        result[BYTE_5] = (byte) ((val & BYTE_5_MASK) >> BYTE_5_SHIFT);
081        result[BYTE_6] = (byte) ((val & BYTE_6_MASK) >> BYTE_6_SHIFT);
082        result[BYTE_7] = (byte) ((val & BYTE_7_MASK) >> BYTE_7_SHIFT);
083        if (value.testBit(LEFTMOST_BIT_SHIFT)) {
084            result[BYTE_7] |= LEFTMOST_BIT;
085        }
086        return result;
087    }
088
089    /**
090     * Get value as eight bytes in big endian byte order.
091     * @param value the value to convert
092     * @return value as eight bytes in big endian byte order
093     */
094    public static byte[] getBytes(final long value) {
095        return getBytes(BigInteger.valueOf(value));
096    }
097
098    /**
099     * Helper method to get the value as a Java long from an eight-byte array
100     * @param bytes the array of bytes
101     * @return the corresponding Java long value
102     */
103    public static long getLongValue(final byte[] bytes) {
104        return getLongValue(bytes, 0);
105    }
106
107    /**
108     * Helper method to get the value as a Java long from eight bytes
109     * starting at given array offset
110     * @param bytes the array of bytes
111     * @param offset the offset to start
112     * @return the corresponding Java long value
113     */
114    public static long getLongValue(final byte[] bytes, final int offset) {
115        return getValue(bytes, offset).longValue();
116    }
117
118    /**
119     * Helper method to get the value as a Java long from an eight-byte array
120     * @param bytes the array of bytes
121     * @return the corresponding Java BigInteger value
122     */
123    public static BigInteger getValue(final byte[] bytes) {
124        return getValue(bytes, 0);
125    }
126
127    /**
128     * Helper method to get the value as a Java BigInteger from eight
129     * bytes starting at given array offset
130     * @param bytes the array of bytes
131     * @param offset the offset to start
132     * @return the corresponding Java BigInteger value
133     */
134    public static BigInteger getValue(final byte[] bytes, final int offset) {
135        long value = ((long) bytes[offset + BYTE_7] << BYTE_7_SHIFT) & BYTE_7_MASK;
136        value += ((long) bytes[offset + BYTE_6] << BYTE_6_SHIFT) & BYTE_6_MASK;
137        value += ((long) bytes[offset + BYTE_5] << BYTE_5_SHIFT) & BYTE_5_MASK;
138        value += ((long) bytes[offset + BYTE_4] << BYTE_4_SHIFT) & BYTE_4_MASK;
139        value += ((long) bytes[offset + BYTE_3] << BYTE_3_SHIFT) & BYTE_3_MASK;
140        value += ((long) bytes[offset + BYTE_2] << BYTE_2_SHIFT) & BYTE_2_MASK;
141        value += ((long) bytes[offset + BYTE_1] << BYTE_1_SHIFT) & BYTE_1_MASK;
142        value += ((long) bytes[offset] & BYTE_MASK);
143        final BigInteger val = BigInteger.valueOf(value);
144        return (bytes[offset + BYTE_7] & LEFTMOST_BIT) == LEFTMOST_BIT
145            ? val.setBit(LEFTMOST_BIT_SHIFT) : val;
146    }
147
148    private final BigInteger value;
149
150    /**
151     * Create instance from a number.
152     * @param value the BigInteger to store as a ZipEightByteInteger
153     */
154    public ZipEightByteInteger(final BigInteger value) {
155        this.value = value;
156    }
157
158    /**
159     * Create instance from bytes.
160     * @param bytes the bytes to store as a ZipEightByteInteger
161     */
162    public ZipEightByteInteger (final byte[] bytes) {
163        this(bytes, 0);
164    }
165
166    /**
167     * Create instance from the eight bytes starting at offset.
168     * @param bytes the bytes to store as a ZipEightByteInteger
169     * @param offset the offset to start
170     */
171    public ZipEightByteInteger (final byte[] bytes, final int offset) {
172        value = ZipEightByteInteger.getValue(bytes, offset);
173    }
174
175    /**
176     * Create instance from a number.
177     * @param value the long to store as a ZipEightByteInteger
178     */
179    public ZipEightByteInteger(final long value) {
180        this(BigInteger.valueOf(value));
181    }
182
183    /**
184     * Override to make two instances with same value equal.
185     * @param o an object to compare
186     * @return true if the objects are equal
187     */
188    @Override
189    public boolean equals(final Object o) {
190        if (!(o instanceof ZipEightByteInteger)) {
191            return false;
192        }
193        return value.equals(((ZipEightByteInteger) o).getValue());
194    }
195
196    /**
197     * Get value as eight bytes in big endian byte order.
198     * @return value as eight bytes in big endian order
199     */
200    public byte[] getBytes() {
201        return ZipEightByteInteger.getBytes(value);
202    }
203
204    /**
205     * Get value as Java long.
206     * @return value as a long
207     */
208    public long getLongValue() {
209        return value.longValue();
210    }
211
212    /**
213     * Get value as Java BigInteger.
214     * @return value as a BigInteger
215     */
216    public BigInteger getValue() {
217        return value;
218    }
219
220    /**
221     * Override to make two instances with same value equal.
222     * @return the hash code of the value stored in the ZipEightByteInteger
223     */
224    @Override
225    public int hashCode() {
226        return value.hashCode();
227    }
228
229    @Override
230    public String toString() {
231        return "ZipEightByteInteger value: " + value;
232    }
233}