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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 1997-2017 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://oss.oracle.com/licenses/CDDL+GPL-1.1
 * or LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
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 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
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 */

package javax.mail.util;

import java.io.*;
import javax.mail.internet.SharedInputStream;

/**
 * A ByteArrayInputStream that implements the SharedInputStream interface,
 * allowing the underlying byte array to be shared between multiple readers.
 *
 * @author  Bill Shannon
 * @since JavaMail 1.4
 */

public class SharedByteArrayInputStream extends ByteArrayInputStream
				implements SharedInputStream {
    /**
     * Position within shared buffer that this stream starts at.
     */
    protected int start = 0;

    /**
     * Create a SharedByteArrayInputStream representing the entire
     * byte array.
     *
     * @param	buf	the byte array
     */
    public SharedByteArrayInputStream(byte[] buf) {
	super(buf);
    }

    /**
     * Create a SharedByteArrayInputStream representing the part
     * of the byte array from offset for length
     * bytes.
     *
     * @param	buf	the byte array
     * @param	offset	offset in byte array to first byte to include
     * @param	length	number of bytes to include
     */
    public SharedByteArrayInputStream(byte[] buf, int offset, int length) {
	super(buf, offset, length);
	start = offset;
    }

    /**
     * Return the current position in the InputStream, as an
     * offset from the beginning of the InputStream.
     *
     * @return  the current position
     */
    @Override
    public long getPosition() {
	return pos - start;
    }

    /**
     * Return a new InputStream representing a subset of the data
     * from this InputStream, starting at start (inclusive)
     * up to end (exclusive).  start must be
     * non-negative.  If end is -1, the new stream ends
     * at the same place as this stream.  The returned InputStream
     * will also implement the SharedInputStream interface.
     *
     * @param	start	the starting position
     * @param	end	the ending position + 1
     * @return		the new stream
     */
    @Override
    public InputStream newStream(long start, long end) {
	if (start < 0)
	    throw new IllegalArgumentException("start < 0");
	if (end == -1)
	    end = count - this.start;
	return new SharedByteArrayInputStream(buf,
				this.start + (int)start, (int)(end - start));
    }
}