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Apache Commons Compress defines an API for working with compression and archive formats. These include bzip2, gzip, pack200, LZMA, XZ, Snappy, traditional Unix Compress, DEFLATE, DEFLATE64, LZ4, Brotli, Zstandard and ar, cpio, jar, tar, zip, dump, 7z, arj.
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/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */
package org.apache.commons.compress.archivers.zip;

import org.apache.commons.compress.utils.ByteUtils;

import java.io.Serializable;

import static org.apache.commons.compress.archivers.zip.ZipConstants.WORD;

/**
 * Utility class that represents a four byte integer with conversion
 * rules for the little endian byte order of ZIP files.
 * @Immutable
 */
public final class ZipLong implements Cloneable, Serializable {
    private static final long serialVersionUID = 1L;

    private final long value;

    /** Central File Header Signature */
    public static final ZipLong CFH_SIG = new ZipLong(0X02014B50L);

    /** Local File Header Signature */
    public static final ZipLong LFH_SIG = new ZipLong(0X04034B50L);

    /**
     * Data Descriptor signature.
     *
     * Actually, PKWARE uses this as marker for split/spanned
     * archives and other archivers have started to use it as Data
     * Descriptor signature (as well).
     * @since 1.1
     */
    public static final ZipLong DD_SIG = new ZipLong(0X08074B50L);

    /**
     * Value stored in size and similar fields if ZIP64 extensions are
     * used.
     * @since 1.3
     */
    static final ZipLong ZIP64_MAGIC = new ZipLong(ZipConstants.ZIP64_MAGIC);

    /**
     * Marks ZIP archives that were supposed to be split or spanned
     * but only needed a single segment in then end (so are actually
     * neither split nor spanned).
     *
     * This is the "PK00" prefix found in some archives.
     * @since 1.5
     */
    public static final ZipLong SINGLE_SEGMENT_SPLIT_MARKER =
        new ZipLong(0X30304B50L);

    /**
     * Archive extra data record signature.
     * @since 1.5
     */
    public static final ZipLong AED_SIG = new ZipLong(0X08064B50L);

    /**
     * Create instance from a number.
     * @param value the long to store as a ZipLong
     */
    public ZipLong(final long value) {
        this.value = value;
    }

    /**
     * create instance from a java int.
     * @param value the int to store as a ZipLong
     * @since 1.15
     */
    public ZipLong(int value) {
        this.value = value;
    }

    /**
     * Create instance from bytes.
     * @param bytes the bytes to store as a ZipLong
     */
    public ZipLong (final byte[] bytes) {
        this(bytes, 0);
    }

    /**
     * Create instance from the four bytes starting at offset.
     * @param bytes the bytes to store as a ZipLong
     * @param offset the offset to start
     */
    public ZipLong (final byte[] bytes, final int offset) {
        value = ZipLong.getValue(bytes, offset);
    }

    /**
     * Get value as four bytes in big endian byte order.
     * @return value as four bytes in big endian order
     */
    public byte[] getBytes() {
        return ZipLong.getBytes(value);
    }

    /**
     * Get value as Java long.
     * @return value as a long
     */
    public long getValue() {
        return value;
    }

    /**
     * Get value as a (signed) java int
     * @return value as int
     * @since 1.15
     */
    public int getIntValue() { return (int)value;}

    /**
     * Get value as four bytes in big endian byte order.
     * @param value the value to convert
     * @return value as four bytes in big endian byte order
     */
    public static byte[] getBytes(final long value) {
        final byte[] result = new byte[WORD];
        putLong(value, result, 0);
        return result;
    }

    /**
     * put the value as four bytes in big endian byte order.
     * @param value the Java long to convert to bytes
     * @param buf the output buffer
     * @param  offset
     *         The offset within the output buffer of the first byte to be written.
     *         must be non-negative and no larger than buf.length-4
     */

    public static void putLong(final long value, final byte[] buf, int offset) {
        ByteUtils.toLittleEndian(buf, value, offset, 4);
    }

    public void putLong(final byte[] buf, final int offset) {
        putLong(value, buf, offset);
    }

    /**
     * Helper method to get the value as a Java long from four bytes starting at given array offset
     * @param bytes the array of bytes
     * @param offset the offset to start
     * @return the corresponding Java long value
     */
    public static long getValue(final byte[] bytes, final int offset) {
        return ByteUtils.fromLittleEndian(bytes, offset, 4);
    }

    /**
     * Helper method to get the value as a Java long from a four-byte array
     * @param bytes the array of bytes
     * @return the corresponding Java long value
     */
    public static long getValue(final byte[] bytes) {
        return getValue(bytes, 0);
    }

    /**
     * Override to make two instances with same value equal.
     * @param o an object to compare
     * @return true if the objects are equal
     */
    @Override
    public boolean equals(final Object o) {
        if (o == null || !(o instanceof ZipLong)) {
            return false;
        }
        return value == ((ZipLong) o).getValue();
    }

    /**
     * Override to make two instances with same value equal.
     * @return the value stored in the ZipLong
     */
    @Override
    public int hashCode() {
        return (int) value;
    }

    @Override
    public Object clone() {
        try {
            return super.clone();
        } catch (final CloneNotSupportedException cnfe) {
            // impossible
            throw new RuntimeException(cnfe); //NOSONAR
        }
    }

    @Override
    public String toString() {
        return "ZipLong value: " + value;
    }
}