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     */
018    package org.apache.commons.compress.archivers.zip;
019    
020    import java.io.Serializable;
021    import java.math.BigInteger;
022    
023    import static org.apache.commons.compress.archivers.zip.ZipConstants.BYTE_MASK;
024    
025    /**
026     * Utility class that represents an eight byte integer with conversion
027     * rules for the big endian byte order of ZIP files.
028     * @Immutable
029     *
030     * @since 1.2
031     */
032    public 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        private final BigInteger value;
067    
068        public static final ZipEightByteInteger ZERO = new ZipEightByteInteger(0);
069    
070        /**
071         * Create instance from a number.
072         * @param value the long to store as a ZipEightByteInteger
073         */
074        public ZipEightByteInteger(long value) {
075            this(BigInteger.valueOf(value));
076        }
077    
078        /**
079         * Create instance from a number.
080         * @param value the BigInteger to store as a ZipEightByteInteger
081         */
082        public ZipEightByteInteger(BigInteger value) {
083            this.value = value;
084        }
085    
086        /**
087         * Create instance from bytes.
088         * @param bytes the bytes to store as a ZipEightByteInteger
089         */
090        public ZipEightByteInteger (byte[] bytes) {
091            this(bytes, 0);
092        }
093    
094        /**
095         * Create instance from the eight bytes starting at offset.
096         * @param bytes the bytes to store as a ZipEightByteInteger
097         * @param offset the offset to start
098         */
099        public ZipEightByteInteger (byte[] bytes, int offset) {
100            value = ZipEightByteInteger.getValue(bytes, offset);
101        }
102    
103        /**
104         * Get value as eight bytes in big endian byte order.
105         * @return value as eight bytes in big endian order
106         */
107        public byte[] getBytes() {
108            return ZipEightByteInteger.getBytes(value);
109        }
110    
111        /**
112         * Get value as Java long.
113         * @return value as a long
114         */
115        public long getLongValue() {
116            return value.longValue();
117        }
118    
119        /**
120         * Get value as Java long.
121         * @return value as a long
122         */
123        public BigInteger getValue() {
124            return value;
125        }
126    
127        /**
128         * Get value as eight bytes in big endian byte order.
129         * @param value the value to convert
130         * @return value as eight bytes in big endian byte order
131         */
132        public static byte[] getBytes(long value) {
133            return getBytes(BigInteger.valueOf(value));
134        }
135    
136        /**
137         * Get value as eight bytes in big endian byte order.
138         * @param value the value to convert
139         * @return value as eight bytes in big endian byte order
140         */
141        public static byte[] getBytes(BigInteger value) {
142            byte[] result = new byte[8];
143            long val = value.longValue();
144            result[0] = (byte) ((val & BYTE_MASK));
145            result[BYTE_1] = (byte) ((val & BYTE_1_MASK) >> BYTE_1_SHIFT);
146            result[BYTE_2] = (byte) ((val & BYTE_2_MASK) >> BYTE_2_SHIFT);
147            result[BYTE_3] = (byte) ((val & BYTE_3_MASK) >> BYTE_3_SHIFT);
148            result[BYTE_4] = (byte) ((val & BYTE_4_MASK) >> BYTE_4_SHIFT);
149            result[BYTE_5] = (byte) ((val & BYTE_5_MASK) >> BYTE_5_SHIFT);
150            result[BYTE_6] = (byte) ((val & BYTE_6_MASK) >> BYTE_6_SHIFT);
151            result[BYTE_7] = (byte) ((val & BYTE_7_MASK) >> BYTE_7_SHIFT);
152            if (value.testBit(LEFTMOST_BIT_SHIFT)) {
153                result[BYTE_7] |= LEFTMOST_BIT;
154            }
155            return result;
156        }
157    
158        /**
159         * Helper method to get the value as a Java long from eight bytes
160         * starting at given array offset
161         * @param bytes the array of bytes
162         * @param offset the offset to start
163         * @return the corresponding Java long value
164         */
165        public static long getLongValue(byte[] bytes, int offset) {
166            return getValue(bytes, offset).longValue();
167        }
168    
169        /**
170         * Helper method to get the value as a Java BigInteger from eight
171         * bytes starting at given array offset
172         * @param bytes the array of bytes
173         * @param offset the offset to start
174         * @return the corresponding Java BigInteger value
175         */
176        public static BigInteger getValue(byte[] bytes, int offset) {
177            long value = ((long) bytes[offset + BYTE_7] << BYTE_7_SHIFT) & BYTE_7_MASK;
178            value += ((long) bytes[offset + BYTE_6] << BYTE_6_SHIFT) & BYTE_6_MASK;
179            value += ((long) bytes[offset + BYTE_5] << BYTE_5_SHIFT) & BYTE_5_MASK;
180            value += ((long) bytes[offset + BYTE_4] << BYTE_4_SHIFT) & BYTE_4_MASK;
181            value += ((long) bytes[offset + BYTE_3] << BYTE_3_SHIFT) & BYTE_3_MASK;
182            value += ((long) bytes[offset + BYTE_2] << BYTE_2_SHIFT) & BYTE_2_MASK;
183            value += ((long) bytes[offset + BYTE_1] << BYTE_1_SHIFT) & BYTE_1_MASK;
184            value += ((long) bytes[offset] & BYTE_MASK);
185            BigInteger val = BigInteger.valueOf(value);
186            return (bytes[offset + BYTE_7] & LEFTMOST_BIT) == LEFTMOST_BIT
187                ? val.setBit(LEFTMOST_BIT_SHIFT) : val;
188        }
189    
190        /**
191         * Helper method to get the value as a Java long from an eight-byte array
192         * @param bytes the array of bytes
193         * @return the corresponding Java long value
194         */
195        public static long getLongValue(byte[] bytes) {
196            return getLongValue(bytes, 0);
197        }
198    
199        /**
200         * Helper method to get the value as a Java long from an eight-byte array
201         * @param bytes the array of bytes
202         * @return the corresponding Java BigInteger value
203         */
204        public static BigInteger getValue(byte[] bytes) {
205            return getValue(bytes, 0);
206        }
207    
208        /**
209         * Override to make two instances with same value equal.
210         * @param o an object to compare
211         * @return true if the objects are equal
212         */
213        @Override
214        public boolean equals(Object o) {
215            if (o == null || !(o instanceof ZipEightByteInteger)) {
216                return false;
217            }
218            return value.equals(((ZipEightByteInteger) o).getValue());
219        }
220    
221        /**
222         * Override to make two instances with same value equal.
223         * @return the hashCode 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    }