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 *
017 */
018package org.apache.commons.compress.archivers.zip;
019
020import static org.apache.commons.compress.archivers.zip.ZipConstants.BYTE_MASK;
021
022import java.io.Serializable;
023import java.math.BigInteger;
024
025/**
026 * Utility class that represents an eight byte integer with conversion
027 * rules for the little endian byte order of ZIP files.
028 * @Immutable
029 *
030 * @since 1.2
031 */
032public final class ZipEightByteInteger implements Serializable {
033    private static final long serialVersionUID = 1L;
034
035    private static final int BYTE_1 = 1;
036    private static final int BYTE_1_MASK = 0xFF00;
037    private static final int BYTE_1_SHIFT = 8;
038
039    private static final int BYTE_2 = 2;
040    private static final int BYTE_2_MASK = 0xFF0000;
041    private static final int BYTE_2_SHIFT = 16;
042
043    private static final int BYTE_3 = 3;
044    private static final long BYTE_3_MASK = 0xFF000000L;
045    private static final int BYTE_3_SHIFT = 24;
046
047    private static final int BYTE_4 = 4;
048    private static final long BYTE_4_MASK = 0xFF00000000L;
049    private static final int BYTE_4_SHIFT = 32;
050
051    private static final int BYTE_5 = 5;
052    private static final long BYTE_5_MASK = 0xFF0000000000L;
053    private static final int BYTE_5_SHIFT = 40;
054
055    private static final int BYTE_6 = 6;
056    private static final long BYTE_6_MASK = 0xFF000000000000L;
057    private static final int BYTE_6_SHIFT = 48;
058
059    private static final int BYTE_7 = 7;
060    private static final long BYTE_7_MASK = 0x7F00000000000000L;
061    private static final int BYTE_7_SHIFT = 56;
062
063    private static final int LEFTMOST_BIT_SHIFT = 63;
064    private static final byte LEFTMOST_BIT = (byte) 0x80;
065
066    public static final ZipEightByteInteger ZERO = new ZipEightByteInteger(0);
067
068    /**
069     * Get value as eight bytes in big endian byte order.
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     * Get value as eight bytes in big endian byte order.
092     * @param value the value to convert
093     * @return value as eight bytes in big endian byte order
094     */
095    public static byte[] getBytes(final long value) {
096        return getBytes(BigInteger.valueOf(value));
097    }
098
099    /**
100     * Helper method to get the value as a Java long from an eight-byte array
101     * @param bytes the array of bytes
102     * @return the corresponding Java long value
103     */
104    public static long getLongValue(final byte[] bytes) {
105        return getLongValue(bytes, 0);
106    }
107
108    /**
109     * Helper method to get the value as a Java long from eight bytes
110     * starting at given array offset
111     * @param bytes the array of bytes
112     * @param offset the offset to start
113     * @return the corresponding Java long value
114     */
115    public static long getLongValue(final byte[] bytes, final int offset) {
116        return getValue(bytes, offset).longValue();
117    }
118
119    /**
120     * Helper method to get the value as a Java long from an eight-byte array
121     * @param bytes the array of bytes
122     * @return the corresponding Java BigInteger value
123     */
124    public static BigInteger getValue(final byte[] bytes) {
125        return getValue(bytes, 0);
126    }
127
128    /**
129     * Helper method to get the value as a Java BigInteger from eight
130     * bytes starting at given array offset
131     * @param bytes the array of bytes
132     * @param offset the offset to start
133     * @return the corresponding Java BigInteger value
134     */
135    public static BigInteger getValue(final byte[] bytes, final int offset) {
136        long value = ((long) bytes[offset + BYTE_7] << BYTE_7_SHIFT) & BYTE_7_MASK;
137        value += ((long) bytes[offset + BYTE_6] << BYTE_6_SHIFT) & BYTE_6_MASK;
138        value += ((long) bytes[offset + BYTE_5] << BYTE_5_SHIFT) & BYTE_5_MASK;
139        value += ((long) bytes[offset + BYTE_4] << BYTE_4_SHIFT) & BYTE_4_MASK;
140        value += ((long) bytes[offset + BYTE_3] << BYTE_3_SHIFT) & BYTE_3_MASK;
141        value += ((long) bytes[offset + BYTE_2] << BYTE_2_SHIFT) & BYTE_2_MASK;
142        value += ((long) bytes[offset + BYTE_1] << BYTE_1_SHIFT) & BYTE_1_MASK;
143        value += ((long) bytes[offset] & BYTE_MASK);
144        final BigInteger val = BigInteger.valueOf(value);
145        return (bytes[offset + BYTE_7] & LEFTMOST_BIT) == LEFTMOST_BIT
146            ? val.setBit(LEFTMOST_BIT_SHIFT) : val;
147    }
148
149    private final BigInteger value;
150
151    /**
152     * Create instance from a number.
153     * @param value the BigInteger to store as a ZipEightByteInteger
154     */
155    public ZipEightByteInteger(final BigInteger value) {
156        this.value = value;
157    }
158
159    /**
160     * Create instance from bytes.
161     * @param bytes the bytes to store as a ZipEightByteInteger
162     */
163    public ZipEightByteInteger (final byte[] bytes) {
164        this(bytes, 0);
165    }
166
167    /**
168     * Create instance from the eight bytes starting at offset.
169     * @param bytes the bytes to store as a ZipEightByteInteger
170     * @param offset the offset to start
171     */
172    public ZipEightByteInteger (final byte[] bytes, final int offset) {
173        value = ZipEightByteInteger.getValue(bytes, offset);
174    }
175
176    /**
177     * Create instance from a number.
178     * @param value the long to store as a ZipEightByteInteger
179     */
180    public ZipEightByteInteger(final long value) {
181        this(BigInteger.valueOf(value));
182    }
183
184    /**
185     * Override to make two instances with same value equal.
186     * @param o an object to compare
187     * @return true if the objects are equal
188     */
189    @Override
190    public boolean equals(final Object o) {
191        if (!(o instanceof ZipEightByteInteger)) {
192            return false;
193        }
194        return value.equals(((ZipEightByteInteger) o).getValue());
195    }
196
197    /**
198     * Get value as eight bytes in big endian byte order.
199     * @return value as eight bytes in big endian order
200     */
201    public byte[] getBytes() {
202        return ZipEightByteInteger.getBytes(value);
203    }
204
205    /**
206     * Get value as Java long.
207     * @return value as a long
208     */
209    public long getLongValue() {
210        return value.longValue();
211    }
212
213    /**
214     * Get value as Java BigInteger.
215     * @return value as a BigInteger
216     */
217    public BigInteger getValue() {
218        return value;
219    }
220
221    /**
222     * Override to make two instances with same value equal.
223     * @return the hash code of the value stored in the ZipEightByteInteger
224     */
225    @Override
226    public int hashCode() {
227        return value.hashCode();
228    }
229
230    @Override
231    public String toString() {
232        return "ZipEightByteInteger value: " + value;
233    }
234}