/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.util.zip;

This class provides support for general purpose decompression 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 java.util.zip
package description.
The following code fragment demonstrates a trivial compression
and decompression of a string using Deflater and
Inflater.
try {
    // Encode a String into bytes
    String inputString = "blahblahblah\u20AC\u20AC";
    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);
    // 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
}

Author:
     David Connelly
See Also:
Deflater/**
 * This class provides support for general purpose decompression 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 <tt>Deflater</tt> and
 * <tt>Inflater</tt>.
 *
 * <blockquote><pre>
 * try {
 *     // Encode a String into bytes
 *     String inputString = "blahblahblah\u20AC\u20AC";
 *     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);
 *
 *     // 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>
 *
 * @see         Deflater
 * @author      David Connelly
 *
 */
public
class Inflater {

    private final ZStreamRef zsRef;
    private byte[] buf = defaultBuf;
    private int off, len;
    private boolean finished;
    private boolean needDict;
    private long bytesRead;
    private long bytesWritten;

    private static final byte[] defaultBuf = new byte[0];

    static {
        /* Zip library is loaded from System.initializeSystemClass */
        initIDs();
    }

    
Creates a new decompressor. If the parameter 'nowrap' is true then
the ZLIB header and checksum fields will not be used. This provides
compatibility with the compression format used by both GZIP and PKZIP.

Note: When using the 'nowrap' option it is also necessary to provide
an extra "dummy" byte as input. This is required by the ZLIB native
library in order to support certain optimizations.
Params:
nowrap – if true then support GZIP compatible compression/**
     * Creates a new decompressor. If the parameter 'nowrap' is true then
     * the ZLIB header and checksum fields will not be used. This provides
     * compatibility with the compression format used by both GZIP and PKZIP.
     * <p>
     * Note: When using the 'nowrap' option it is also necessary to provide
     * an extra "dummy" byte as input. This is required by the ZLIB native
     * library in order to support certain optimizations.
     *
     * @param nowrap if true then support GZIP compatible compression
     */
    public Inflater(boolean nowrap) {
        zsRef = new ZStreamRef(init(nowrap));
    }

    
Creates a new decompressor.
/**
     * Creates a new decompressor.
     */
    public Inflater() {
        this(false);
    }

    
Sets input data for decompression. Should be called whenever
needsInput() returns true indicating that more input data is
required.
Params:
b – the input data bytes
off – the start offset of the input data
len – the length of the input data
See Also:
needsInput/**
     * Sets input data for decompression. 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 input data
     * @param len the length of the input data
     * @see Inflater#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 decompression. Should be called whenever
needsInput() returns true indicating that more input data is
required.
Params:
b – the input data bytes
See Also:
needsInput/**
     * Sets input data for decompression. Should be called whenever
     * needsInput() returns true indicating that more input data is
     * required.
     * @param b the input data bytes
     * @see Inflater#needsInput
     */
    public void setInput(byte[] b) {
        setInput(b, 0, b.length);
    }

    
Sets the preset dictionary to the given array of bytes. Should be
called when inflate() returns 0 and needsDictionary() returns true
indicating that a preset dictionary is required. The method getAdler()
can be used to get the Adler-32 value of the dictionary needed.
Params:
b – the dictionary data bytes
off – the start offset of the data
len – the length of the data
See Also:
needsDictionary
getAdler/**
     * Sets the preset dictionary to the given array of bytes. Should be
     * called when inflate() returns 0 and needsDictionary() returns true
     * indicating that a preset dictionary is required. The method getAdler()
     * can be used to get the Adler-32 value of the dictionary needed.
     * @param b the dictionary data bytes
     * @param off the start offset of the data
     * @param len the length of the data
     * @see Inflater#needsDictionary
     * @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);
            needDict = false;
        }
    }

    
Sets the preset dictionary to the given array of bytes. Should be
called when inflate() returns 0 and needsDictionary() returns true
indicating that a preset dictionary is required. The method getAdler()
can be used to get the Adler-32 value of the dictionary needed.
Params:
b – the dictionary data bytes
See Also:
needsDictionary
getAdler/**
     * Sets the preset dictionary to the given array of bytes. Should be
     * called when inflate() returns 0 and needsDictionary() returns true
     * indicating that a preset dictionary is required. The method getAdler()
     * can be used to get the Adler-32 value of the dictionary needed.
     * @param b the dictionary data bytes
     * @see Inflater#needsDictionary
     * @see Inflater#getAdler
     */
    public void setDictionary(byte[] b) {
        setDictionary(b, 0, b.length);
    }

    
Returns the total number of bytes remaining in the input buffer.
This can be used to find out what bytes still remain in the input
buffer after decompression has finished.
Returns:
the total number of bytes remaining in the input buffer/**
     * Returns the total number of bytes remaining in the input buffer.
     * This can be used to find out what bytes still remain in the input
     * buffer after decompression has finished.
     * @return the total number of bytes remaining in the input buffer
     */
    public int getRemaining() {
        synchronized (zsRef) {
            return len;
        }
    }

    
Returns true if no data remains in the input buffer. This can
be used to determine if #setInput should be called in order
to provide more input.
Returns:
true if no data remains in the input buffer/**
     * Returns true if no data remains in the input buffer. This can
     * be used to determine if #setInput should be called in order
     * to provide more input.
     * @return true if no data remains in the input buffer
     */
    public boolean needsInput() {
        synchronized (zsRef) {
            return len <= 0;
        }
    }

    
Returns true if a preset dictionary is needed for decompression.
See Also:
setDictionary
Returns:
true if a preset dictionary is needed for decompression/**
     * Returns true if a preset dictionary is needed for decompression.
     * @return true if a preset dictionary is needed for decompression
     * @see Inflater#setDictionary
     */
    public boolean needsDictionary() {
        synchronized (zsRef) {
            return needDict;
        }
    }

    
Returns true if the end of the compressed data stream has been
reached.
Returns:
true if the end of the compressed data stream has been
reached/**
     * Returns true if the end of the compressed data stream has been
     * reached.
     * @return true if the end of the compressed data stream has been
     * reached
     */
    public boolean finished() {
        synchronized (zsRef) {
            return finished;
        }
    }

    
Uncompresses bytes into specified buffer. Returns actual number
of bytes uncompressed. A return value of 0 indicates that
needsInput() or needsDictionary() should be called in order to
determine if more input data or a preset dictionary is required.
In the latter case, getAdler() can be used to get the Adler-32
value of the dictionary required.
Params:
b – the buffer for the uncompressed data
off – the start offset of the data
len – the maximum number of uncompressed bytes
Throws:
DataFormatException – if the compressed data format is invalid
See Also:
needsInput
needsDictionary
Returns:
the actual number of uncompressed bytes/**
     * Uncompresses bytes into specified buffer. Returns actual number
     * of bytes uncompressed. A return value of 0 indicates that
     * needsInput() or needsDictionary() should be called in order to
     * determine if more input data or a preset dictionary is required.
     * In the latter case, getAdler() can be used to get the Adler-32
     * value of the dictionary required.
     * @param b the buffer for the uncompressed data
     * @param off the start offset of the data
     * @param len the maximum number of uncompressed bytes
     * @return the actual number of uncompressed bytes
     * @exception DataFormatException if the compressed data format is invalid
     * @see Inflater#needsInput
     * @see Inflater#needsDictionary
     */
    public int inflate(byte[] b, int off, int len)
        throws DataFormatException
    {
        if (b == null) {
            throw new NullPointerException();
        }
        if (off < 0 || len < 0 || off > b.length - len) {
            throw new ArrayIndexOutOfBoundsException();
        }
        synchronized (zsRef) {
            ensureOpen();
            int thisLen = this.len;
            int n = inflateBytes(zsRef.address(), b, off, len);
            bytesWritten += n;
            bytesRead += (thisLen - this.len);
            return n;
        }
    }

    
Uncompresses bytes into specified buffer. Returns actual number
of bytes uncompressed. A return value of 0 indicates that
needsInput() or needsDictionary() should be called in order to
determine if more input data or a preset dictionary is required.
In the latter case, getAdler() can be used to get the Adler-32
value of the dictionary required.
Params:
b – the buffer for the uncompressed data
Throws:
DataFormatException – if the compressed data format is invalid
See Also:
needsInput
needsDictionary
Returns:
the actual number of uncompressed bytes/**
     * Uncompresses bytes into specified buffer. Returns actual number
     * of bytes uncompressed. A return value of 0 indicates that
     * needsInput() or needsDictionary() should be called in order to
     * determine if more input data or a preset dictionary is required.
     * In the latter case, getAdler() can be used to get the Adler-32
     * value of the dictionary required.
     * @param b the buffer for the uncompressed data
     * @return the actual number of uncompressed bytes
     * @exception DataFormatException if the compressed data format is invalid
     * @see Inflater#needsInput
     * @see Inflater#needsDictionary
     */
    public int inflate(byte[] b) throws DataFormatException {
        return inflate(b, 0, b.length);
    }

    
Returns the ADLER-32 value of the uncompressed data.
Returns:
the ADLER-32 value of the uncompressed data/**
     * 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 compressed bytes input so far.
Since the number of bytes may be greater than Integer.MAX_VALUE, the getBytesRead() method is now the preferred means of obtaining this information.
Returns:
the total number of compressed bytes input so far/**
     * Returns the total number of compressed 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 compressed bytes input so far
     */
    public int getTotalIn() {
        return (int) getBytesRead();
    }

    
Returns the total number of compressed bytes input so far.
Returns:
the total (non-negative) number of compressed bytes input so far
Since:
1.5/**
     * Returns the total number of compressed bytes input so far.
     *
     * @return the total (non-negative) number of compressed bytes input so far
     * @since 1.5
     */
    public long getBytesRead() {
        synchronized (zsRef) {
            ensureOpen();
            return bytesRead;
        }
    }

    
Returns the total number of uncompressed bytes output so far.
Since the number of bytes may be greater than Integer.MAX_VALUE, the getBytesWritten() method is now the preferred means of obtaining this information.
Returns:
the total number of uncompressed bytes output so far/**
     * Returns the total number of uncompressed bytes output so far.
     *
     * <p>Since the number of bytes may be greater than
     * Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now
     * the preferred means of obtaining this information.</p>
     *
     * @return the total number of uncompressed bytes output so far
     */
    public int getTotalOut() {
        return (int) getBytesWritten();
    }

    
Returns the total number of uncompressed bytes output so far.
Returns:
the total (non-negative) number of uncompressed bytes output so far
Since:
1.5/**
     * Returns the total number of uncompressed bytes output so far.
     *
     * @return the total (non-negative) number of uncompressed bytes output so far
     * @since 1.5
     */
    public long getBytesWritten() {
        synchronized (zsRef) {
            ensureOpen();
            return bytesWritten;
        }
    }

    
Resets inflater so that a new set of input data can be processed.
/**
     * Resets inflater so that a new set of input data can be processed.
     */
    public void reset() {
        synchronized (zsRef) {
            ensureOpen();
            reset(zsRef.address());
            buf = defaultBuf;
            finished = false;
            needDict = false;
            off = len = 0;
            bytesRead = bytesWritten = 0;
        }
    }

    
Closes the decompressor and discards any unprocessed input.
This method should be called when the decompressor is no longer
being used, but will also be called automatically by the finalize()
method. Once this method is called, the behavior of the Inflater
object is undefined.
/**
     * Closes the decompressor and discards any unprocessed input.
     * This method should be called when the decompressor is no longer
     * being used, but will also be called automatically by the finalize()
     * method. Once this method is called, the behavior of the Inflater
     * object is undefined.
     */
    public void end() {
        synchronized (zsRef) {
            long addr = zsRef.address();
            zsRef.clear();
            if (addr != 0) {
                end(addr);
                buf = null;
            }
        }
    }

    
Closes the decompressor when garbage is collected.
/**
     * Closes the decompressor when garbage is collected.
     */
    protected void finalize() {
        end();
    }

    private void ensureOpen () {
        assert Thread.holdsLock(zsRef);
        if (zsRef.address() == 0)
            throw new NullPointerException("Inflater has been closed");
    }

    boolean ended() {
        synchronized (zsRef) {
            return zsRef.address() == 0;
        }
    }

    private native static void initIDs();
    private native static long init(boolean nowrap);
    private native static void setDictionary(long addr, byte[] b, int off,
                                             int len);
    private native int inflateBytes(long addr, byte[] b, int off, int len)
            throws DataFormatException;
    private native static int getAdler(long addr);
    private native static void reset(long addr);
    private native static void end(long addr);
}