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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

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 * accompanied this code).

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package java.util.zip;

import java.lang.ref.Cleaner.Cleanable;

import java.lang.ref.Reference;

import java.nio.ByteBuffer;

import java.nio.ReadOnlyBufferException;

import java.util.Objects;

import jdk.internal.ref.CleanerFactory;

import sun.nio.ch.DirectBuffer;

/**

 * This class provides support for general purpose compression using the

 * popular ZLIB compression library. The ZLIB compression library was

 * initially developed as part of the PNG graphics standard and is not

 * protected by patents. It is fully described in the specifications at

 * the <a href="package-summary.html#package.description">java.util.zip

 * package description</a>.

 * <p>

 * This class deflates sequences of bytes into ZLIB compressed data format.

 * The input byte sequence is provided in either byte array or byte buffer,

 * via one of the {@code setInput()} methods. The output byte sequence is

 * written to the output byte array or byte buffer passed to the

 * {@code deflate()} methods.

 * <p>

 * The following code fragment demonstrates a trivial compression

 * and decompression of a string using {@code Deflater} and

 * {@code Inflater}.

 *

 * <blockquote><pre>

 * try {

 *     // Encode a String into bytes

 *     String inputString = "blahblahblah";

 *     byte[] input = inputString.getBytes("UTF-8");

 *

 *     // Compress the bytes

 *     byte[] output = new byte[100];

 *     Deflater compresser = new Deflater();

 *     compresser.setInput(input);

 *     compresser.finish();

 *     int compressedDataLength = compresser.deflate(output);

 *     compresser.end();

 *

 *     // Decompress the bytes

 *     Inflater decompresser = new Inflater();

 *     decompresser.setInput(output, 0, compressedDataLength);

 *     byte[] result = new byte[100];

 *     int resultLength = decompresser.inflate(result);

 *     decompresser.end();

 *

 *     // Decode the bytes into a String

 *     String outputString = new String(result, 0, resultLength, "UTF-8");

 *     // handle

 * } catch (java.util.zip.DataFormatException ex) {

 *     // handle

 * }

 * </pre></blockquote>

 *

 * @apiNote

 * To release resources used by this {@code Deflater}, the {@link #end()} method

 * should be called explicitly. Subclasses are responsible for the cleanup of resources

 * acquired by the subclass. Subclasses that override {@link #finalize()} in order

 * to perform cleanup should be modified to use alternative cleanup mechanisms such

 * as {@link java.lang.ref.Cleaner} and remove the overriding {@code finalize} method.

 *

 * @implSpec

 * If this {@code Deflater} has been subclassed and the {@code end} method has been

 * overridden, the {@code end} method will be called by the finalization when the

 * deflater is unreachable. But the subclasses should not depend on this specific

 * implementation; the finalization is not reliable and the {@code finalize} method

 * is deprecated to be removed.

 *

 * @see         Inflater

 * @author      David Connelly

 * @since 1.1

 */

public class Deflater {

    private final DeflaterZStreamRef zsRef;

    private ByteBuffer input = ZipUtils.defaultBuf;

    private byte[] inputArray;

    private int inputPos, inputLim;

    private int level, strategy;

    private boolean setParams;

    private boolean finish, finished;

    private long bytesRead;

    private long bytesWritten;

    /**

     * Compression method for the deflate algorithm (the only one currently

     * supported).

     */

    public static final int DEFLATED = 8;

    /**

     * Compression level for no compression.

     */

    public static final int NO_COMPRESSION = 0;

    /**

     * Compression level for fastest compression.

     */

    public static final int BEST_SPEED = 1;

    /**

     * Compression level for best compression.

     */

    public static final int BEST_COMPRESSION = 9;

    /**

     * Default compression level.

     */

    public static final int DEFAULT_COMPRESSION = -1;

    /**

     * Compression strategy best used for data consisting mostly of small

     * values with a somewhat random distribution. Forces more Huffman coding

     * and less string matching.

     */

    public static final int FILTERED = 1;

    /**

     * Compression strategy for Huffman coding only.

     */

    public static final int HUFFMAN_ONLY = 2;

    /**

     * Default compression strategy.

     */

    public static final int DEFAULT_STRATEGY = 0;

    /**

     * Compression flush mode used to achieve best compression result.

     *

     * @see Deflater#deflate(byte[], int, int, int)

     * @since 1.7

     */

    public static final int NO_FLUSH = 0;

    /**

     * Compression flush mode used to flush out all pending output; may

     * degrade compression for some compression algorithms.

     *

     * @see Deflater#deflate(byte[], int, int, int)

     * @since 1.7

     */

    public static final int SYNC_FLUSH = 2;

    /**

     * Compression flush mode used to flush out all pending output and

     * reset the deflater. Using this mode too often can seriously degrade

     * compression.

     *

     * @see Deflater#deflate(byte[], int, int, int)

     * @since 1.7

     */

    public static final int FULL_FLUSH = 3;

    /**

     * Flush mode to use at the end of output.  Can only be provided by the

     * user by way of {@link #finish()}.

     */

    private static final int FINISH = 4;

    static {

        ZipUtils.loadLibrary();

    }

    /**

     * Creates a new compressor using the specified compression level.

     * If 'nowrap' is true then the ZLIB header and checksum fields will

     * not be used in order to support the compression format used in

     * both GZIP and PKZIP.

     * @param level the compression level (0-9)

     * @param nowrap if true then use GZIP compatible compression

     */

    public Deflater(int level, boolean nowrap) {

        this.level = level;

        this.strategy = DEFAULT_STRATEGY;

        this.zsRef = DeflaterZStreamRef.get(this,

                                    init(level, DEFAULT_STRATEGY, nowrap));

    }

    /**

     * Creates a new compressor using the specified compression level.

     * Compressed data will be generated in ZLIB format.

     * @param level the compression level (0-9)

     */

    public Deflater(int level) {

        this(level, false);

    }

    /**

     * Creates a new compressor with the default compression level.

     * Compressed data will be generated in ZLIB format.

     */

    public Deflater() {

        this(DEFAULT_COMPRESSION, false);

    }

    /**

     * Sets input data for compression.

     * <p>

     * One of the {@code setInput()} methods should be called whenever

     * {@code needsInput()} returns true indicating that more input data

     * is required.

     * <p>

     * @param input the input data bytes

     * @param off the start offset of the data

     * @param len the length of the data

     * @see Deflater#needsInput

     */

    public void setInput(byte[] input, int off, int len) {

        if (off < 0 || len < 0 || off > input.length - len) {

            throw new ArrayIndexOutOfBoundsException();

        }

        synchronized (zsRef) {

            this.input = null;

            this.inputArray = input;

            this.inputPos = off;

            this.inputLim = off + len;

        }

    }

    /**

     * Sets input data for compression.

     * <p>

     * One of the {@code setInput()} methods should be called whenever

     * {@code needsInput()} returns true indicating that more input data

     * is required.

     * <p>

     * @param input the input data bytes

     * @see Deflater#needsInput

     */

    public void setInput(byte[] input) {

        setInput(input, 0, input.length);

    }

    /**

     * Sets input data for compression.

     * <p>

     * One of the {@code setInput()} methods should be called whenever

     * {@code needsInput()} returns true indicating that more input data

     * is required.

     * <p>

     * The given buffer's position will be advanced as deflate

     * operations are performed, up to the buffer's limit.

     * The input buffer may be modified (refilled) between deflate

     * operations; doing so is equivalent to creating a new buffer

     * and setting it with this method.

     * <p>

     * Modifying the input buffer's contents, position, or limit

     * concurrently with an deflate operation will result in

     * undefined behavior, which may include incorrect operation

     * results or operation failure.

     *

     * @param input the input data bytes

     * @see Deflater#needsInput

     * @since 11

     */

    public void setInput(ByteBuffer input) {

        Objects.requireNonNull(input);

        synchronized (zsRef) {

            this.input = input;

            this.inputArray = null;

        }

    }

    /**

     * Sets preset dictionary for compression. A preset dictionary is used

     * when the history buffer can be predetermined. When the data is later

     * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called

     * in order to get the Adler-32 value of the dictionary required for

     * decompression.

     * @param dictionary the dictionary data bytes

     * @param off the start offset of the data

     * @param len the length of the data

     * @see Inflater#inflate

     * @see Inflater#getAdler

     */

    public void setDictionary(byte[] dictionary, int off, int len) {

        if (off < 0 || len < 0 || off > dictionary.length - len) {

            throw new ArrayIndexOutOfBoundsException();

        }

        synchronized (zsRef) {

            ensureOpen();

            setDictionary(zsRef.address(), dictionary, off, len);

        }

    }

    /**

     * Sets preset dictionary for compression. A preset dictionary is used

     * when the history buffer can be predetermined. When the data is later

     * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called

     * in order to get the Adler-32 value of the dictionary required for

     * decompression.

     * @param dictionary the dictionary data bytes

     * @see Inflater#inflate

     * @see Inflater#getAdler

     */

    public void setDictionary(byte[] dictionary) {

        setDictionary(dictionary, 0, dictionary.length);

    }

    /**

     * Sets preset dictionary for compression. A preset dictionary is used

     * when the history buffer can be predetermined. When the data is later

     * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called

     * in order to get the Adler-32 value of the dictionary required for

     * decompression.

     * <p>

     * The bytes in given byte buffer will be fully consumed by this method.  On

     * return, its position will equal its limit.

     *

     * @param dictionary the dictionary data bytes

     * @see Inflater#inflate

     * @see Inflater#getAdler

     */

    public void setDictionary(ByteBuffer dictionary) {

        synchronized (zsRef) {

            int position = dictionary.position();

            int remaining = Math.max(dictionary.limit() - position, 0);

            ensureOpen();

            if (dictionary.isDirect()) {

                long address = ((DirectBuffer) dictionary).address();

                try {

                    setDictionaryBuffer(zsRef.address(), address + position, remaining);

                } finally {

                    Reference.reachabilityFence(dictionary);

                }

            } else {

                byte[] array = ZipUtils.getBufferArray(dictionary);

                int offset = ZipUtils.getBufferOffset(dictionary);

                setDictionary(zsRef.address(), array, offset + position, remaining);

            }

            dictionary.position(position + remaining);

        }

    }

    /**

     * Sets the compression strategy to the specified value.

     *

     * <p> If the compression strategy is changed, the next invocation

     * of {@code deflate} will compress the input available so far with

     * the old strategy (and may be flushed); the new strategy will take

     * effect only after that invocation.

     *

     * @param strategy the new compression strategy

     * @exception IllegalArgumentException if the compression strategy is

     *                                     invalid

     */

    public void setStrategy(int strategy) {

        switch (strategy) {

          case DEFAULT_STRATEGY:

          case FILTERED:

          case HUFFMAN_ONLY:

            break;

          default:

            throw new IllegalArgumentException();

        }

        synchronized (zsRef) {

            if (this.strategy != strategy) {

                this.strategy = strategy;

                setParams = true;

            }

        }

    }

    /**

     * Sets the compression level to the specified value.

     *

     * <p> If the compression level is changed, the next invocation

     * of {@code deflate} will compress the input available so far

     * with the old level (and may be flushed); the new level will

     * take effect only after that invocation.

     *

     * @param level the new compression level (0-9)

     * @exception IllegalArgumentException if the compression level is invalid

     */

    public void setLevel(int level) {

        if ((level < 0 || level > 9) && level != DEFAULT_COMPRESSION) {

            throw new IllegalArgumentException("invalid compression level");

        }

        synchronized (zsRef) {

            if (this.level != level) {

                this.level = level;

                setParams = true;

            }

        }

    }

    /**

     * Returns true if no data remains in the input buffer. This can

     * be used to determine if one of the {@code setInput()} methods should be

     * called in order to provide more input.

     *

     * @return true if the input data buffer is empty and setInput()

     * should be called in order to provide more input

     */

    public boolean needsInput() {

        synchronized (zsRef) {

            ByteBuffer input = this.input;

            return input == null ? inputLim == inputPos : ! input.hasRemaining();

        }

    }

    /**

     * When called, indicates that compression should end with the current

     * contents of the input buffer.

     */

    public void finish() {

        synchronized (zsRef) {

            finish = true;

        }

    }

    /**

     * Returns true if the end of the compressed data output stream has

     * been reached.

     * @return true if the end of the compressed data output stream has

     * been reached

     */

    public boolean finished() {

        synchronized (zsRef) {

            return finished;

        }

    }

    /**

     * Compresses the input data and fills specified buffer with compressed

     * data. Returns actual number of bytes of compressed data. A return value

     * of 0 indicates that {@link #needsInput() needsInput} should be called

     * in order to determine if more input data is required.

     *

     * <p>This method uses {@link #NO_FLUSH} as its compression flush mode.

     * An invocation of this method of the form {@code deflater.deflate(b, off, len)}

     * yields the same result as the invocation of

     * {@code deflater.deflate(b, off, len, Deflater.NO_FLUSH)}.

     *

     * @param output the buffer for the compressed data

     * @param off the start offset of the data

     * @param len the maximum number of bytes of compressed data

     * @return the actual number of bytes of compressed data written to the

     *         output buffer

     */

    public int deflate(byte[] output, int off, int len) {

        return deflate(output, off, len, NO_FLUSH);

    }

    /**

     * Compresses the input data and fills specified buffer with compressed

     * data. Returns actual number of bytes of compressed data. A return value

     * of 0 indicates that {@link #needsInput() needsInput} should be called

     * in order to determine if more input data is required.

     *

     * <p>This method uses {@link #NO_FLUSH} as its compression flush mode.

     * An invocation of this method of the form {@code deflater.deflate(b)}

     * yields the same result as the invocation of

     * {@code deflater.deflate(b, 0, b.length, Deflater.NO_FLUSH)}.

     *

     * @param output the buffer for the compressed data

     * @return the actual number of bytes of compressed data written to the

     *         output buffer

     */

    public int deflate(byte[] output) {

        return deflate(output, 0, output.length, NO_FLUSH);

    }

    /**

     * Compresses the input data and fills specified buffer with compressed

     * data. Returns actual number of bytes of compressed data. A return value

     * of 0 indicates that {@link #needsInput() needsInput} should be called

     * in order to determine if more input data is required.

     *

     * <p>This method uses {@link #NO_FLUSH} as its compression flush mode.

     * An invocation of this method of the form {@code deflater.deflate(output)}