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	/*
	* Copyright (c) 1994, 2010, 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.io;

	/**
	* A <code>FilterInputStream</code> contains
	* some other input stream, which it uses as
	* its basic source of data, possibly transforming
	* the data along the way or providing additional
	* functionality. The class <code>FilterInputStream</code>
	* itself simply overrides all methods of
	* <code>InputStream</code> with versions that
	* pass all requests to the contained input
	* stream. Subclasses of <code>FilterInputStream</code>
	* may further override some of these methods
	* and may also provide additional methods
	* and fields.
	*
	* @author Jonathan Payne
	* @since JDK1.0
	*/
	public
	class FilterInputStream extends InputStream {
	/**
	* The input stream to be filtered.
	*/
	protected volatile InputStream in;

	/**
	* Creates a <code>FilterInputStream</code>
	* by assigning the argument <code>in</code>
	* to the field <code>this.in</code> so as
	* to remember it for later use.
	*
	* @param in the underlying input stream, or <code>null</code> if
	* this instance is to be created without an underlying stream.
	*/
	protected FilterInputStream(InputStream in) {
	this.in = in;
	}

	/**
	* Reads the next byte of data from this input stream. The value
	* byte is returned as an <code>int</code> in the range
	* <code>0</code> to <code>255</code>. If no byte is available
	* because the end of the stream has been reached, the value
	* <code>-1</code> is returned. This method blocks until input data
	* is available, the end of the stream is detected, or an exception
	* is thrown.
	* <p>
	* This method
	* simply performs <code>in.read()</code> and returns the result.
	*
	* @return the next byte of data, or <code>-1</code> if the end of the
	* stream is reached.
	* @exception IOException if an I/O error occurs.
	* @see java.io.FilterInputStream#in
	*/
	public int read() throws IOException {
	return in.read();
	}

	/**
	* Reads up to <code>byte.length</code> bytes of data from this
	* input stream into an array of bytes. This method blocks until some
	* input is available.
	* <p>
	* This method simply performs the call
	* <code>read(b, 0, b.length)</code> and returns
	* the result. It is important that it does
	* <i>not</i> do <code>in.read(b)</code> instead;
	* certain subclasses of <code>FilterInputStream</code>
	* depend on the implementation strategy actually
	* used.
	*
	* @param b the buffer into which the data is read.
	* @return the total number of bytes read into the buffer, or
	* <code>-1</code> if there is no more data because the end of
	* the stream has been reached.
	* @exception IOException if an I/O error occurs.
	* @see java.io.FilterInputStream#read(byte[], int, int)
	*/
	public int read(byte b[]) throws IOException {
	return read(b, 0, b.length);
	}

	/**
	* Reads up to <code>len</code> bytes of data from this input stream
	* into an array of bytes. If <code>len</code> is not zero, the method
	* blocks until some input is available; otherwise, no
	* bytes are read and <code>0</code> is returned.
	* <p>
	* This method simply performs <code>in.read(b, off, len)</code>
	* and returns the result.
	*
	* @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 total number of bytes read into the buffer, or
	* <code>-1</code> if there is no more data because the end of
	* the stream has been reached.
	* @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 IOException if an I/O error occurs.
	* @see java.io.FilterInputStream#in
	*/
	public int read(byte b[], int off, int len) throws IOException {
	return in.read(b, off, len);
	}

	/**
	* Skips over and discards <code>n</code> bytes of data from the
	* input stream. The <code>skip</code> method may, for a variety of
	* reasons, end up skipping over some smaller number of bytes,
	* possibly <code>0</code>. The actual number of bytes skipped is
	* returned.
	* <p>
	* This method simply performs <code>in.skip(n)</code>.
	*
	* @param n the number of bytes to be skipped.
	* @return the actual number of bytes skipped.
	* @exception IOException if the stream does not support seek,
	* or if some other I/O error occurs.
	*/
	public long skip(long n) throws IOException {
	return in.skip(n);
	}

	/**
	* Returns an estimate of the number of bytes that can be read (or
	* skipped over) from this input stream without blocking by the next
	* caller of a method for this input stream. The next caller might be
	* the same thread or another thread. A single read or skip of this
	* many bytes will not block, but may read or skip fewer bytes.
	* <p>
	* This method returns the result of {@link #in in}.available().
	*
	* @return an estimate of the number of bytes that can be read (or skipped
	* over) from this input stream without blocking.
	* @exception IOException if an I/O error occurs.
	*/
	public int available() throws IOException {
	return in.available();
	}

	/**
	* Closes this input stream and releases any system resources
	* associated with the stream.
	* This
	* method simply performs <code>in.close()</code>.
	*
	* @exception IOException if an I/O error occurs.
	* @see java.io.FilterInputStream#in
	*/
	public void close() throws IOException {
	in.close();
	}

	/**
	* Marks the current position in this input stream. A subsequent
	* call to the <code>reset</code> method repositions this stream at
	* the last marked position so that subsequent reads re-read the same bytes.
	* <p>
	* The <code>readlimit</code> argument tells this input stream to
	* allow that many bytes to be read before the mark position gets
	* invalidated.
	* <p>
	* This method simply performs <code>in.mark(readlimit)</code>.
	*
	* @param readlimit the maximum limit of bytes that can be read before
	* the mark position becomes invalid.
	* @see java.io.FilterInputStream#in
	* @see java.io.FilterInputStream#reset()
	*/
	public synchronized void mark(int readlimit) {
	in.mark(readlimit);
	}

	/**
	* Repositions this stream to the position at the time the
	* <code>mark</code> method was last called on this input stream.
	* <p>
	* This method
	* simply performs <code>in.reset()</code>.
	* <p>
	* Stream marks are intended to be used in
	* situations where you need to read ahead a little to see what's in
	* the stream. Often this is most easily done by invoking some
	* general parser. If the stream is of the type handled by the
	* parse, it just chugs along happily. If the stream is not of
	* that type, the parser should toss an exception when it fails.
	* If this happens within readlimit bytes, it allows the outer
	* code to reset the stream and try another parser.
	*
	* @exception IOException if the stream has not been marked or if the
	* mark has been invalidated.
	* @see java.io.FilterInputStream#in
	* @see java.io.FilterInputStream#mark(int)
	*/
	public synchronized void reset() throws IOException {
	in.reset();
	}

	/**
	* Tests if this input stream supports the <code>mark</code>
	* and <code>reset</code> methods.
	* This method
	* simply performs <code>in.markSupported()</code>.
	*
	* @return <code>true</code> if this stream type supports the
	* <code>mark</code> and <code>reset</code> method;
	* <code>false</code> otherwise.
	* @see java.io.FilterInputStream#in
	* @see java.io.InputStream#mark(int)
	* @see java.io.InputStream#reset()
	*/
	public boolean markSupported() {
	return in.markSupported();
	}
	}

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