/*

  * Copyright (c) 1996, 2006, 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

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 package java.util.zip;

 import java.io.FilterInputStream;

 import java.io.InputStream;

 import java.io.IOException;

 import java.io.EOFException;

 /**

  * This class implements a stream filter for uncompressing data in the

  * "deflate" compression format. It is also used as the basis for other

  * decompression filters, such as GZIPInputStream.

  *

  * @see         Inflater

  * @author      David Connelly

  */

 public

 class InflaterInputStream extends FilterInputStream {

     /**

      * Decompressor for this stream.

      */

     protected Inflater inf;

     /**

      * Input buffer for decompression.

      */

     protected byte[] buf;

     /**

      * Length of input buffer.

      */

     protected int len;

     private boolean closed = false;

     // this flag is set to true after EOF has reached

     private boolean reachEOF = false;

     /**

      * Check to make sure that this stream has not been closed

      */

     private void ensureOpen() throws IOException {

         if (closed) {

             throw new IOException("Stream closed");

         }

     }

     /**

      * Creates a new input stream with the specified decompressor and

      * buffer size.

      * @param in the input stream

      * @param inf the decompressor ("inflater")

      * @param size the input buffer size

      * @exception IllegalArgumentException if size is <= 0

      */

     public InflaterInputStream(InputStream in, Inflater inf, int size) {

         super(in);

         if (in == null || inf == null) {

             throw new NullPointerException();

         } else if (size <= 0) {

             throw new IllegalArgumentException("buffer size <= 0");

         }

         this.inf = inf;

         buf = new byte[size];

     }

     /**

      * Creates a new input stream with the specified decompressor and a

      * default buffer size.

      * @param in the input stream

      * @param inf the decompressor ("inflater")

      */

     public InflaterInputStream(InputStream in, Inflater inf) {

         this(in, inf, 512);

     }

     boolean usesDefaultInflater = false;

     /**

      * Creates a new input stream with a default decompressor and buffer size.

      * @param in the input stream

      */

     public InflaterInputStream(InputStream in) {

         this(in, new Inflater());

         usesDefaultInflater = true;

     }

     private byte[] singleByteBuf = new byte[1];

     /**

      * Reads a byte of uncompressed data. This method will block until

      * enough input is available for decompression.

      * @return the byte read, or -1 if end of compressed input is reached

      * @exception IOException if an I/O error has occurred

      */

     public int read() throws IOException {

         ensureOpen();

         return read(singleByteBuf, 0, 1) == -1 ? -1 : singleByteBuf[0] & 0xff;

     }

     /**

      * Reads uncompressed data into an array of bytes. If <code>len</code> is not

      * zero, the method will block until some input can be decompressed; otherwise,

      * no bytes are read and <code>0</code> is returned.

      * @param b the buffer into which the data is read

      * @param off the start offset in the destination array <code>b</code>

      * @param len the maximum number of bytes read

      * @return the actual number of bytes read, or -1 if the end of the

      *         compressed input is reached or a preset dictionary is needed

      * @exception  NullPointerException If <code>b</code> is <code>null</code>.

      * @exception  IndexOutOfBoundsException If <code>off</code> is negative,

      * <code>len</code> is negative, or <code>len</code> is greater than

      * <code>b.length - off</code>

      * @exception ZipException if a ZIP format error has occurred

      * @exception IOException if an I/O error has occurred

      */

     public int read(byte[] b, int off, int len) throws IOException {

         ensureOpen();

         if (b == null) {

             throw new NullPointerException();

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

             throw new IndexOutOfBoundsException();

         } else if (len == 0) {

             return 0;

         }

         try {

             int n;

             while ((n = inf.inflate(b, off, len)) == 0) {

                 if (inf.finished() || inf.needsDictionary()) {

                     reachEOF = true;

                     return -1;

                 }

                 if (inf.needsInput()) {

                     fill();

                 }

             }

             return n;

         } catch (DataFormatException e) {

             String s = e.getMessage();

             throw new ZipException(s != null ? s : "Invalid ZLIB data format");

         }

     }

     /**

      * Returns 0 after EOF has been reached, otherwise always return 1.

      * <p>

      * Programs should not count on this method to return the actual number

      * of bytes that could be read without blocking.

      *

      * @return     1 before EOF and 0 after EOF.

      * @exception  IOException  if an I/O error occurs.

      *

      */

     public int available() throws IOException {

         ensureOpen();

         if (reachEOF) {

             return 0;

         } else {

             return 1;

         }

     }

     private byte[] b = new byte[512];

     /**

      * Skips specified number of bytes of uncompressed data.

      * @param n the number of bytes to skip

      * @return the actual number of bytes skipped.

      * @exception IOException if an I/O error has occurred

      * @exception IllegalArgumentException if n < 0

      */

     public long skip(long n) throws IOException {

         if (n < 0) {

             throw new IllegalArgumentException("negative skip length");

         }

         ensureOpen();

         int max = (int)Math.min(n, Integer.MAX_VALUE);

         int total = 0;

         while (total < max) {

             int len = max - total;

             if (len > b.length) {

                 len = b.length;

             }

             len = read(b, 0, len);

             if (len == -1) {

                 reachEOF = true;

                 break;

             }

             total += len;

         }

         return total;

     }

     /**

      * Closes this input stream and releases any system resources associated

      * with the stream.

      * @exception IOException if an I/O error has occurred

      */

     public void close() throws IOException {

         if (!closed) {

             if (usesDefaultInflater)

                 inf.end();

             in.close();

             closed = true;

         }

     }

     /**

      * Fills input buffer with more data to decompress.

      * @exception IOException if an I/O error has occurred

      */

     protected void fill() throws IOException {

         ensureOpen();

         len = in.read(buf, 0, buf.length);

         if (len == -1) {

             throw new EOFException("Unexpected end of ZLIB input stream");

         }

         inf.setInput(buf, 0, len);

     }

     /**

      * Tests if this input stream supports the <code>mark</code> and

      * <code>reset</code> methods. The <code>markSupported</code>

      * method of <code>InflaterInputStream</code> returns

      * <code>false</code>.

      *

      * @return  a <code>boolean</code> indicating if this stream type supports

      *          the <code>mark</code> and <code>reset</code> methods.

      * @see     java.io.InputStream#mark(int)

      * @see     java.io.InputStream#reset()

      */

     public boolean markSupported() {

         return false;

     }

     /**

      * Marks the current position in this input stream.

      *

      * <p> The <code>mark</code> method of <code>InflaterInputStream</code>

      * does nothing.

      *

      * @param   readlimit   the maximum limit of bytes that can be read before

      *                      the mark position becomes invalid.

      * @see     java.io.InputStream#reset()

      */

     public synchronized void mark(int readlimit) {

     }

     /**

      * Repositions this stream to the position at the time the

      * <code>mark</code> method was last called on this input stream.

      *

      * <p> The method <code>reset</code> for class

      * <code>InflaterInputStream</code> does nothing except throw an

      * <code>IOException</code>.

      *

      * @exception  IOException  if this method is invoked.

      * @see     java.io.InputStream#mark(int)

      * @see     java.io.IOException

      */

     public synchronized void reset() throws IOException {

         throw new IOException("mark/reset not supported");

     }

 }