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 * Copyright (c) 2001, 2014, 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 com.sun.imageio.plugins.jpeg;

import javax.imageio.metadata.IIOInvalidTreeException;
import javax.imageio.metadata.IIOMetadataNode;
import javax.imageio.stream.ImageOutputStream;
import javax.imageio.IIOException;

import java.io.IOException;

import org.w3c.dom.Node;
import org.w3c.dom.NamedNodeMap;

All metadata is stored in MarkerSegments.  Marker segments
that we know about are stored in subclasses of this
basic class, which used for unrecognized APPn marker
segments.  XXX break out UnknownMarkerSegment as a subclass
and make this abstract, avoiding unused data field.
/**
 * All metadata is stored in MarkerSegments.  Marker segments
 * that we know about are stored in subclasses of this
 * basic class, which used for unrecognized APPn marker
 * segments.  XXX break out UnknownMarkerSegment as a subclass
 * and make this abstract, avoiding unused data field.
 */
class MarkerSegment implements Cloneable {
    protected static final int LENGTH_SIZE = 2; // length is 2 bytes
    int tag;      // See JPEG.java
    int length;    /* Sometimes needed by subclasses; doesn't include
                      itself.  Meaningful only if constructed from a stream */
    byte [] data = null;  // Raw segment data, used for unrecognized segments
    boolean unknown = false; // Set to true if the tag is not recognized

    
Constructor for creating MarkerSegments by reading from an ImageInputStream. /**
     * Constructor for creating {@code MarkerSegment}s by reading
     * from an {@code ImageInputStream}.
     */
    MarkerSegment(JPEGBuffer buffer) throws IOException {

        buffer.loadBuf(3);  // tag plus length
        tag = buffer.buf[buffer.bufPtr++] & 0xff;
        length = (buffer.buf[buffer.bufPtr++] & 0xff) << 8;
        length |= buffer.buf[buffer.bufPtr++] & 0xff;
        length -= 2;  // JPEG length includes itself, we don't

        if (length < 0) {
            throw new IIOException("Invalid segment length: " + length);
        }
        buffer.bufAvail -= 3;
        // Now that we know the true length, ensure that we've got it,
        // or at least a bufferful if length is too big.
        buffer.loadBuf(length);
    }

    
Constructor used when creating segments other than by
reading them from a stream.
/**
     * Constructor used when creating segments other than by
     * reading them from a stream.
     */
    MarkerSegment(int tag) {
        this.tag = tag;
        length = 0;
    }

    
Construct a MarkerSegment from an "unknown" DOM Node.
/**
     * Construct a MarkerSegment from an "unknown" DOM Node.
     */
    MarkerSegment(Node node) throws IIOInvalidTreeException {
        // The type of node should have been verified already.
        // get the attribute and assign it to the tag
        tag = getAttributeValue(node,
                                null,
                                "MarkerTag",
                                0, 255,
                                true);
        length = 0;
        // get the user object and clone it to the data
        if (node instanceof IIOMetadataNode) {
            IIOMetadataNode iioNode = (IIOMetadataNode) node;
            try {
                data = (byte []) iioNode.getUserObject();
            } catch (Exception e) {
                IIOInvalidTreeException newGuy =
                    new IIOInvalidTreeException
                    ("Can't get User Object", node);
                newGuy.initCause(e);
                throw newGuy;
            }
        } else {
            throw new IIOInvalidTreeException
                ("Node must have User Object", node);
        }
    }

    
Deep copy of data array.
/**
     * Deep copy of data array.
     */
    protected Object clone() {
        MarkerSegment newGuy = null;
        try {
            newGuy = (MarkerSegment) super.clone();
        } catch (CloneNotSupportedException e) {} // won't happen
        if (this.data != null) {
            newGuy.data = data.clone();
        }
        return newGuy;
    }

    
We have determined that we don't know the type, so load
the data using the length parameter.
/**
     * We have determined that we don't know the type, so load
     * the data using the length parameter.
     */
    void loadData(JPEGBuffer buffer) throws IOException {
        data = new byte[length];
        buffer.readData(data);
    }

    IIOMetadataNode getNativeNode() {
        IIOMetadataNode node = new IIOMetadataNode("unknown");
        node.setAttribute("MarkerTag", Integer.toString(tag));
        node.setUserObject(data);

        return node;
    }

    static int getAttributeValue(Node node,
                                 NamedNodeMap attrs,
                                 String name,
                                 int min,
                                 int max,
                                 boolean required)
        throws IIOInvalidTreeException {
        if (attrs == null) {
            attrs = node.getAttributes();
        }
        String valueString = attrs.getNamedItem(name).getNodeValue();
        int value = -1;
        if (valueString == null) {
            if (required) {
                throw new IIOInvalidTreeException
                    (name + " attribute not found", node);
            }
        } else {
              value = Integer.parseInt(valueString);
              if ((value < min) || (value > max)) {
                  throw new IIOInvalidTreeException
                      (name + " attribute out of range", node);
              }
        }
        return value;
    }

    
Writes the marker, tag, and length.  Note that length
should be verified by the caller as a correct JPEG
length, i.e it includes itself.
/**
     * Writes the marker, tag, and length.  Note that length
     * should be verified by the caller as a correct JPEG
     * length, i.e it includes itself.
     */
    void writeTag(ImageOutputStream ios) throws IOException {
        ios.write(0xff);
        ios.write(tag);
        write2bytes(ios, length);
    }

    
Writes the data for this segment to the stream in
valid JPEG format.
/**
     * Writes the data for this segment to the stream in
     * valid JPEG format.
     */
    void write(ImageOutputStream ios) throws IOException {
        length = 2 + ((data != null) ? data.length : 0);
        writeTag(ios);
        if (data != null) {
            ios.write(data);
        }
    }

    static void write2bytes(ImageOutputStream ios,
                            int value) throws IOException {
        ios.write((value >> 8) & 0xff);
        ios.write(value & 0xff);

    }

    void printTag(String prefix) {
        System.out.println(prefix + " marker segment - marker = 0x"
                           + Integer.toHexString(tag));
        System.out.println("length: " + length);
    }

    void print() {
        printTag("Unknown");
        if (length > 10) {
            System.out.print("First 5 bytes:");
            for (int i=0;i<5;i++) {
                System.out.print(" Ox"
                                 + Integer.toHexString((int)data[i]));
            }
            System.out.print("\nLast 5 bytes:");
            for (int i=data.length-5;i<data.length;i++) {
                System.out.print(" Ox"
                                 + Integer.toHexString((int)data[i]));
            }
        } else {
            System.out.print("Data:");
            for (int i=0;i<data.length;i++) {
                System.out.print(" Ox"
                                 + Integer.toHexString((int)data[i]));
            }
        }
        System.out.println();
    }
}