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

 *

 * This code is free software; you can redistribute it and/or modify it

 * 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

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

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

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package java.util.zip;

/**

 * 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>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");

 * } catch(java.io.UnsupportedEncodingException ex) {

 *     // 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 byte[] buf = new byte[0];

    private int off, len;

    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;

    static {

        ZipUtils.loadLibrary();

        initIDs();

    }

    /**

     * 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;

    }

    /**

     * 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. This should be called whenever

     * needsInput() returns true indicating that more input data is required.

     * @param b 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[] b, int off, int len) {

        if (b== null) {

            throw new NullPointerException();

        }

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

            throw new ArrayIndexOutOfBoundsException();

        }

        synchronized (zsRef) {

            this.buf = b;

            this.off = off;

            this.len = len;

        }

    }

    /**

     * Sets input data for compression. This should be called whenever

     * needsInput() returns true indicating that more input data is required.

     * @param b the input data bytes

     * @see Deflater#needsInput

     */

    public void setInput(byte[] b) {

        setInput(b, 0, b.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.

     * @param b 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[] b, int off, int len) {

        if (b == null) {

            throw new NullPointerException();

        }

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

            throw new ArrayIndexOutOfBoundsException();

        }

        synchronized (zsRef) {

            ensureOpen();

            setDictionary(zsRef.address(), b, 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 b the dictionary data bytes

     * @see Inflater#inflate

     * @see Inflater#getAdler

     */

    public void setDictionary(byte[] b) {

        setDictionary(b, 0, b.length);

    }

    /**

     * 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 the input data buffer is empty and setInput()

     * 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) {

            return len <= 0;

        }

    }

    /**

     * 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 b 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[] b, int off, int len) {

        return deflate(b, 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 b the buffer for the compressed data

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

     *         output buffer

     */

    public int deflate(byte[] b) {

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

    }

    /**

     * Compresses the input data and fills the specified buffer with compressed

     * data. Returns actual number of bytes of data compressed.

     *

     * <p>Compression flush mode is one of the following three modes:

     *

     * <ul>

     * <li>{@link #NO_FLUSH}: allows the deflater to decide how much data

     * to accumulate, before producing output, in order to achieve the best

     * compression (should be used in normal use scenario). A return value

     * of 0 in this flush mode indicates that {@link #needsInput()} should

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

     *

     * <li>{@link #SYNC_FLUSH}: all pending output in the deflater is flushed,

     * to the specified output buffer, so that an inflater that works on

     * compressed data can get all input data available so far (In particular

     * the {@link #needsInput()} returns {@code true} after this invocation

     * if enough output space is provided). Flushing with {@link #SYNC_FLUSH}

     * may degrade compression for some compression algorithms and so it

     * should be used only when necessary.

     *

     * <li>{@link #FULL_FLUSH}: all pending output is flushed out as with

     * {@link #SYNC_FLUSH}. The compression state is reset so that the inflater

     * that works on the compressed output data can restart from this point

     * if previous compressed data has been damaged or if random access is

     * desired. Using {@link #FULL_FLUSH} too often can seriously degrade

     * compression.

     * </ul>

     *

     * <p>In the case of {@link #FULL_FLUSH} or {@link #SYNC_FLUSH}, if

     * the return value is {@code len}, the space available in output

     * buffer {@code b}, this method should be invoked again with the same

     * {@code flush} parameter and more output space. Make sure that

     * {@code len} is greater than 6 to avoid flush marker (5 bytes) being

     * repeatedly output to the output buffer every time this method is

     * invoked.

     *

     * @param b the buffer for the compressed data

     * @param off the start offset of the data

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

     * @param flush the compression flush mode

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

     *         the output buffer

     *

     * @throws IllegalArgumentException if the flush mode is invalid

     * @since 1.7

     */

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

        if (b == null) {

            throw new NullPointerException();

        }

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

            throw new ArrayIndexOutOfBoundsException();

        }

        synchronized (zsRef) {

            ensureOpen();

            if (flush == NO_FLUSH || flush == SYNC_FLUSH ||

                flush == FULL_FLUSH) {

                int thisLen = this.len;

                int n = deflateBytes(zsRef.address(), b, off, len, flush);

                bytesWritten += n;

                bytesRead += (thisLen - this.len);

                return n;

            }

            throw new IllegalArgumentException();

        }

    }

    /**

     * Returns the ADLER-32 value of the uncompressed data.

     * @return the ADLER-32 value of the uncompressed data

     */

    public int getAdler() {

        synchronized (zsRef) {

            ensureOpen();

            return getAdler(zsRef.address());

        }

    }

    /**

     * Returns the total number of uncompressed bytes input so far.

     *

     * <p>Since the number of bytes may be greater than

     * Integer.MAX_VALUE, the {@link #getBytesRead()} method is now

     * the preferred means of obtaining this information.</p>

     *

     * @return the total number of uncompressed bytes input so far

     */

    public int getTotalIn() {

        return (int) getBytesRead();

    }

    /**

     * Returns the total number of uncompressed bytes input so far.

     *

     * @return the total (non-negative) number of uncompressed bytes input so far

     * @since 1.5

     */

    public long getBytesRead() {

        synchronized (zsRef) {

            ensureOpen();

            return bytesRead;