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    
022    import static org.apache.commons.compress.archivers.zip.ZipConstants.BYTE_MASK;
023    import static org.apache.commons.compress.archivers.zip.ZipConstants.WORD;
024    
025    /**
026     * Utility class that represents a four byte integer with conversion
027     * rules for the big endian byte order of ZIP files.
028     * @Immutable
029     */
030    public final class ZipLong implements Cloneable, Serializable {
031        private static final long serialVersionUID = 1L;
032    
033        //private static final int BYTE_BIT_SIZE = 8;
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 final long value;
048    
049        /** Central File Header Signature */
050        public static final ZipLong CFH_SIG = new ZipLong(0X02014B50L);
051    
052        /** Local File Header Signature */
053        public static final ZipLong LFH_SIG = new ZipLong(0X04034B50L);
054    
055        /**
056         * Data Descriptor signature.
057         *
058         * <p>Actually, PKWARE uses this as marker for split/spanned
059         * archives and other archivers have started to use it as Data
060         * Descriptor signature (as well).</p>
061         * @since 1.1
062         */
063        public static final ZipLong DD_SIG = new ZipLong(0X08074B50L);
064    
065        /**
066         * Value stored in size and similar fields if ZIP64 extensions are
067         * used.
068         * @since 1.3
069         */
070        static final ZipLong ZIP64_MAGIC = new ZipLong(ZipConstants.ZIP64_MAGIC);
071    
072        /**
073         * Marks ZIP archives that were supposed to be split or spanned
074         * but only needed a single segment in then end (so are actually
075         * neither split nor spanned).
076         *
077         * <p>This is the "PK00" prefix found in some archives.</p>
078         * @since 1.5
079         */
080        public static final ZipLong SINGLE_SEGMENT_SPLIT_MARKER =
081            new ZipLong(0X30304B50L);
082    
083        /**
084         * Archive extra data record signature.</p>
085         * @since 1.5
086         */
087        public static final ZipLong AED_SIG = new ZipLong(0X08064B50L);
088    
089        /**
090         * Create instance from a number.
091         * @param value the long to store as a ZipLong
092         */
093        public ZipLong(long value) {
094            this.value = value;
095        }
096    
097        /**
098         * Create instance from bytes.
099         * @param bytes the bytes to store as a ZipLong
100         */
101        public ZipLong (byte[] bytes) {
102            this(bytes, 0);
103        }
104    
105        /**
106         * Create instance from the four bytes starting at offset.
107         * @param bytes the bytes to store as a ZipLong
108         * @param offset the offset to start
109         */
110        public ZipLong (byte[] bytes, int offset) {
111            value = ZipLong.getValue(bytes, offset);
112        }
113    
114        /**
115         * Get value as four bytes in big endian byte order.
116         * @return value as four bytes in big endian order
117         */
118        public byte[] getBytes() {
119            return ZipLong.getBytes(value);
120        }
121    
122        /**
123         * Get value as Java long.
124         * @return value as a long
125         */
126        public long getValue() {
127            return value;
128        }
129    
130        /**
131         * Get value as four bytes in big endian byte order.
132         * @param value the value to convert
133         * @return value as four bytes in big endian byte order
134         */
135        public static byte[] getBytes(long value) {
136            byte[] result = new byte[WORD];
137            result[0] = (byte) ((value & BYTE_MASK));
138            result[BYTE_1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
139            result[BYTE_2] = (byte) ((value & BYTE_2_MASK) >> BYTE_2_SHIFT);
140            result[BYTE_3] = (byte) ((value & BYTE_3_MASK) >> BYTE_3_SHIFT);
141            return result;
142        }
143    
144        /**
145         * Helper method to get the value as a Java long from four bytes starting at given array offset
146         * @param bytes the array of bytes
147         * @param offset the offset to start
148         * @return the corresponding Java long value
149         */
150        public static long getValue(byte[] bytes, int offset) {
151            long value = (bytes[offset + BYTE_3] << BYTE_3_SHIFT) & BYTE_3_MASK;
152            value += (bytes[offset + BYTE_2] << BYTE_2_SHIFT) & BYTE_2_MASK;
153            value += (bytes[offset + BYTE_1] << BYTE_1_SHIFT) & BYTE_1_MASK;
154            value += (bytes[offset] & BYTE_MASK);
155            return value;
156        }
157    
158        /**
159         * Helper method to get the value as a Java long from a four-byte array
160         * @param bytes the array of bytes
161         * @return the corresponding Java long value
162         */
163        public static long getValue(byte[] bytes) {
164            return getValue(bytes, 0);
165        }
166    
167        /**
168         * Override to make two instances with same value equal.
169         * @param o an object to compare
170         * @return true if the objects are equal
171         */
172        @Override
173        public boolean equals(Object o) {
174            if (o == null || !(o instanceof ZipLong)) {
175                return false;
176            }
177            return value == ((ZipLong) o).getValue();
178        }
179    
180        /**
181         * Override to make two instances with same value equal.
182         * @return the value stored in the ZipLong
183         */
184        @Override
185        public int hashCode() {
186            return (int) value;
187        }
188    
189        @Override
190        public Object clone() {
191            try {
192                return super.clone();
193            } catch (CloneNotSupportedException cnfe) {
194                // impossible
195                throw new RuntimeException(cnfe);
196            }
197        }
198    
199        @Override
200        public String toString() {
201            return "ZipLong value: " + value;
202        }
203    }