    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 static org.apache.commons.compress.archivers.zip.ZipConstants.BYTE_MASK;
    021    import static org.apache.commons.compress.archivers.zip.ZipConstants.WORD;
    022
    023    /**
    024     * Utility class that represents a four byte integer with conversion
    025     * rules for the big endian byte order of ZIP files.
    026     * @Immutable
    027     */
    028    public final class ZipLong implements Cloneable {
    029
    030        //private static final int BYTE_BIT_SIZE = 8;
    031
    032        private static final int BYTE_1 = 1;
    033        private static final int BYTE_1_MASK = 0xFF00;
    034        private static final int BYTE_1_SHIFT = 8;
    035
    036        private static final int BYTE_2 = 2;
    037        private static final int BYTE_2_MASK = 0xFF0000;
    038        private static final int BYTE_2_SHIFT = 16;
    039
    040        private static final int BYTE_3 = 3;
    041        private static final long BYTE_3_MASK = 0xFF000000L;
    042        private static final int BYTE_3_SHIFT = 24;
    043
    044        private final long value;
    045
    046        /** Central File Header Signature */
    047        public static final ZipLong CFH_SIG = new ZipLong(0X02014B50L);
    048
    049        /** Local File Header Signature */
    050        public static final ZipLong LFH_SIG = new ZipLong(0X04034B50L);
    051
    052        /**
    053         * Data Descriptor signature
    054         * @since Apache Commons Compress 1.1
    055         */
    056        public static final ZipLong DD_SIG = new ZipLong(0X08074B50L);
    057
    058        /**
    059         * Value stored in size and similar fields if ZIP64 extensions are
    060         * used.
    061         * @since Apache Commons Compress 1.3
    062         */
    063        static final ZipLong ZIP64_MAGIC = new ZipLong(ZipConstants.ZIP64_MAGIC);
    064
    065        /**
    066         * Create instance from a number.
    067         * @param value the long to store as a ZipLong
    068         */
    069        public ZipLong(long value) {
    070            this.value = value;
    071        }
    072
    073        /**
    074         * Create instance from bytes.
    075         * @param bytes the bytes to store as a ZipLong
    076         */
    077        public ZipLong (byte[] bytes) {
    078            this(bytes, 0);
    079        }
    080
    081        /**
    082         * Create instance from the four bytes starting at offset.
    083         * @param bytes the bytes to store as a ZipLong
    084         * @param offset the offset to start
    085         */
    086        public ZipLong (byte[] bytes, int offset) {
    087            value = ZipLong.getValue(bytes, offset);
    088        }
    089
    090        /**
    091         * Get value as four bytes in big endian byte order.
    092         * @return value as four bytes in big endian order
    093         */
    094        public byte[] getBytes() {
    095            return ZipLong.getBytes(value);
    096        }
    097
    098        /**
    099         * Get value as Java long.
    100         * @return value as a long
    101         */
    102        public long getValue() {
    103            return value;
    104        }
    105
    106        /**
    107         * Get value as four bytes in big endian byte order.
    108         * @param value the value to convert
    109         * @return value as four bytes in big endian byte order
    110         */
    111        public static byte[] getBytes(long value) {
    112            byte[] result = new byte[WORD];
    113            result[0] = (byte) ((value & BYTE_MASK));
    114            result[BYTE_1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
    115            result[BYTE_2] = (byte) ((value & BYTE_2_MASK) >> BYTE_2_SHIFT);
    116            result[BYTE_3] = (byte) ((value & BYTE_3_MASK) >> BYTE_3_SHIFT);
    117            return result;
    118        }
    119
    120        /**
    121         * Helper method to get the value as a Java long from four bytes starting at given array offset
    122         * @param bytes the array of bytes
    123         * @param offset the offset to start
    124         * @return the corresponding Java long value
    125         */
    126        public static long getValue(byte[] bytes, int offset) {
    127            long value = (bytes[offset + BYTE_3] << BYTE_3_SHIFT) & BYTE_3_MASK;
    128            value += (bytes[offset + BYTE_2] << BYTE_2_SHIFT) & BYTE_2_MASK;
    129            value += (bytes[offset + BYTE_1] << BYTE_1_SHIFT) & BYTE_1_MASK;
    130            value += (bytes[offset] & BYTE_MASK);
    131            return value;
    132        }
    133
    134        /**
    135         * Helper method to get the value as a Java long from a four-byte array
    136         * @param bytes the array of bytes
    137         * @return the corresponding Java long value
    138         */
    139        public static long getValue(byte[] bytes) {
    140            return getValue(bytes, 0);
    141        }
    142
    143        /**
    144         * Override to make two instances with same value equal.
    145         * @param o an object to compare
    146         * @return true if the objects are equal
    147         */
    148        @Override
    149        public boolean equals(Object o) {
    150            if (o == null || !(o instanceof ZipLong)) {
    151                return false;
    152            }
    153            return value == ((ZipLong) o).getValue();
    154        }
    155
    156        /**
    157         * Override to make two instances with same value equal.
    158         * @return the value stored in the ZipLong
    159         */
    160        @Override
    161        public int hashCode() {
    162            return (int) value;
    163        }
    164
    165        @Override
    166        public Object clone() {
    167            try {
    168                return super.clone();
    169            } catch (CloneNotSupportedException cnfe) {
    170                // impossible
    171                throw new RuntimeException(cnfe);
    172            }
    173        }
    174
    175        @Override
    176        public String toString() {
    177            return "ZipLong value: " + value;
    178        }
    179    }