de.intarsys.pdf.cos.COSTrailer Maven / Gradle / Ivy

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/*
 * Copyright (c) 2007, intarsys consulting GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * - Neither the name of intarsys nor the names of its contributors may be used
 *   to endorse or promote products derived from this software without specific
 *   prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package de.intarsys.pdf.cos;

import java.security.MessageDigest;
import java.util.Iterator;

import de.intarsys.tools.locator.ILocator;
import de.intarsys.tools.randomaccess.IRandomAccess;
import de.intarsys.tools.randomaccess.RandomAccessByteArray;
import de.intarsys.tools.string.StringTools;

/**
 * The document trailer.
 */
public class COSTrailer extends COSBasedObject {
	/**
	 * The meta class implementation
	 */
	public static class MetaClass extends COSBasedObject.MetaClass {
		protected MetaClass(Class instanceClass) {
			super(instanceClass);
		}

		@Override
		protected COSBasedObject doCreateCOSBasedObject(COSObject object) {
			return new COSTrailer(object);
		}
	}

	/** The well known attribute names */
	public static final COSName DK_Info = COSName.constant("Info"); //$NON-NLS-1$

	public static final COSName DK_Prev = COSName.constant("Prev"); //$NON-NLS-1$

	public static final COSName DK_Root = COSName.constant("Root"); //$NON-NLS-1$

	public static final COSName DK_Size = COSName.constant("Size"); //$NON-NLS-1$

	public static final COSName DK_Encrypt = COSName.constant("Encrypt"); //$NON-NLS-1$

	public static final COSName DK_ID = COSName.constant("ID"); //$NON-NLS-1$

	public static final COSName DK_XRefStm = COSName.constant("XRefStm"); //$NON-NLS-1$

	/** The meta class instance */
	public static final MetaClass META = new MetaClass(
			MetaClass.class.getDeclaringClass());

	/** The cached catalog object */
	private COSCatalog cachedCatalog;

	protected COSTrailer(COSObject object) {
		super(object);
	}

	/**
	 * The dynamic file id part.
	 */
	public COSString cosGetDynamicFileID() {
		COSArray fileID = cosGetField(DK_ID).asArray();
		if ((fileID == null) || (fileID.size() < 2)) {
			return null;
		} else {
			return (COSString) fileID.get(1);
		}
	}

	/**
	 * The /Encrypt field of the trailer.
	 * 
	 * @return The /Encrypt field of the trailer.
	 */
	public COSDictionary cosGetEncryption() {
		return cosGetField(DK_Encrypt).asDictionary();
	}

	/**
	 * The current file id or null
	 */
	public COSArray cosGetFileID() {
		return cosGetField(DK_ID).asArray();
	}

	/**
	 * The /ID field of the trailer.
	 * 
	 * @return The /ID field of the trailer.
	 */
	public COSArray cosGetID() {
		return cosGetField(DK_ID).asArray();
	}

	/**
	 * The permanent file id part.
	 */
	public COSString cosGetPermanentFileID() {
		COSArray fileID = cosGetField(DK_ID).asArray();
		if ((fileID == null) || (fileID.size() == 0)) {
			return null;
		} else {
			return (COSString) fileID.get(0);
		}
	}

	/**
	 * Set the /Encrypt field of the trailer.
	 * 
	 * @param encryption
	 *            The new encryption dictionary
	 */
	public void cosSetEncryption(COSDictionary encryption) {
		cosSetField(DK_Encrypt, encryption);
	}

	/**
	 *  
	 * - include time 
	 * - file location 
	 * - size 
	 * - document information dictionary 
	 * 
	 * 
	 * @return a byte array with the created ID
	 */
	protected byte[] createFileID() {
		try {
			COSDocument cosDoc = cosGetDoc();
			if (cosDoc == null) {
				return null;
			}
			ILocator locator = cosDoc.getLocator();
			if (locator == null) {
				return null;
			}
			IRandomAccess ra = cosDoc.stGetDoc().getRandomAccess();
			if (ra == null) {
				ra = new RandomAccessByteArray(
						StringTools.toByteArray("DummyValue")); //$NON-NLS-1$
			}
			MessageDigest digest = MessageDigest.getInstance("MD5"); //$NON-NLS-1$
			long time = System.currentTimeMillis();
			digest.update(String.valueOf(time).getBytes());
			digest.update(locator.getFullName().getBytes());
			// this is the previous length! - but should not matter
			digest.update(String.valueOf(ra.getLength()).getBytes());
			COSInfoDict infoDict = getInfoDict();
			if (infoDict != null) {
				for (Iterator it = infoDict.cosGetDict().iterator(); it
						.hasNext();) {
					COSObject object = (COSObject) it.next();
					String tempString = object.stringValue();
					if (tempString != null) {
						digest.update(tempString.getBytes());
					}
				}
			}
			return digest.digest();
		} catch (Exception e) {
			throw new IllegalStateException(e);
		}
	}

	/**
	 * The {@link COSInfoDict} containing metadata.
	 * 
	 * @return The {@link COSInfoDict} containing metadata.
	 */
	public COSInfoDict getInfoDict() {
		return (COSInfoDict) COSInfoDict.META
				.createFromCos(cosGetField(DK_Info).asDictionary());
	}

	/**
	 * 
	 * @return Offset of previous trailer dict or -1 if none exists
	 */
	public int getPrev() {
		return getFieldInt(DK_Prev, -1);
	}

	/**
	 * Get the root object (the catalog) for the document.
	 * 
	 * @return The root object (the catalog) for the document.
	 */
	public COSCatalog getRoot() {
		if (cachedCatalog == null) {
			cachedCatalog = (COSCatalog) COSCatalog.META
					.createFromCos(cosGetField(DK_Root));
		}
		return cachedCatalog;
	}

	/**
	 * @return Total number of indirect objects in the document
	 */
	public int getSize() {
		return getFieldInt(DK_Size, -1);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see de.intarsys.pdf.cos.COSBasedObject#initializeFromScratch()
	 */
	@Override
	protected void initializeFromScratch() {
		super.initializeFromScratch();
		setRoot((COSCatalog) COSCatalog.META.createNew());
		setInfoDict((COSInfoDict) COSInfoDict.META.createNew());
	}

	@Override
	public void invalidateCaches() {
		super.invalidateCaches();
		cachedCatalog = null;
	}

	/**
	 * Set the info dictionary containing metadata.
	 * 
	 * @param infoDict
	 *            The info dictionary containing metadata.
	 */
	public void setInfoDict(COSInfoDict infoDict) {
		setFieldObject(DK_Info, infoDict);
	}

	/**
	 * Set the catalog.
	 * 
	 * @param root
	 *            The document catalog
	 */
	public void setRoot(COSCatalog root) {
		setFieldObject(DK_Root, root);
	}

	/**
	 * Generates a unique file ID array (10.3).
	 */
	public void updateFileID() {
		COSArray fileID = cosGetField(DK_ID).asArray();
		if ((fileID == null) || (fileID.size() == 0)) {
			fileID = COSArray.create();
			cosSetField(DK_ID, fileID);
			byte[] id = createFileID();
			COSString permanentID = COSString.create(id);
			fileID.add(permanentID);
			fileID.add(permanentID);
		} else {
			byte[] id = createFileID();
			COSString changingID = COSString.create(id);
			if (fileID.size() < 2) {
				fileID.add(changingID);
			} else {
				fileID.set(1, changingID);
			}
		}
	}
}