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/*
This file is part of the iText (R) project.
Copyright (c) 1998-2024 Apryse Group NV
Authors: Apryse Software.
This program is offered under a commercial and under the AGPL license.
For commercial licensing, contact us at https://itextpdf.com/sales. For AGPL licensing, see below.
AGPL licensing:
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see .
*/
package com.itextpdf.kernel.pdf;
import com.itextpdf.io.source.ByteBuffer;
import com.itextpdf.kernel.exceptions.PdfException;
import java.security.MessageDigest;
import java.util.HashMap;
import java.util.Map;
class SmartModePdfObjectsSerializer {
private MessageDigest sha512;
private HashMap serializedContentToObj = new HashMap<>();
SmartModePdfObjectsSerializer() {
try {
sha512 = MessageDigest.getInstance("SHA-512");
} catch (Exception e) {
throw new PdfException(e);
}
}
public void saveSerializedObject(SerializedObjectContent serializedContent, PdfIndirectReference objectReference) {
serializedContentToObj.put(serializedContent, objectReference);
}
public PdfIndirectReference getSavedSerializedObject(SerializedObjectContent serializedContent) {
if (serializedContent != null) {
return serializedContentToObj.get(serializedContent);
}
return null;
}
public SerializedObjectContent serializeObject(PdfObject obj) {
if (!obj.isStream() && !obj.isDictionary()) {
return null;
}
PdfIndirectReference indRef = obj.getIndirectReference();
assert indRef != null;
Map serializedCache = indRef.getDocument().serializedObjectsCache;
byte[] content = serializedCache.get(indRef);
if (content == null) {
ByteBuffer bb = new ByteBuffer();
int level = 100;
try {
serObject(obj, bb, level, serializedCache);
} catch (SelfReferenceException e) {
return null;
}
content = bb.toByteArray();
}
return new SerializedObjectContent(content);
}
private void serObject(PdfObject obj, ByteBuffer bb, int level, Map serializedCache) throws SelfReferenceException {
if (level <= 0) {
return;
}
if (obj == null) {
bb.append("$Lnull");
return;
}
PdfIndirectReference reference = null;
ByteBuffer savedBb = null;
if (obj.isIndirectReference()) {
reference = (PdfIndirectReference) obj;
byte[] cached = serializedCache.get(reference);
if (cached != null) {
bb.append(cached);
return;
} else {
if (serializedCache.keySet().contains(reference)) {
//referencing itself
throw new SelfReferenceException();
}
serializedCache.put(reference, null);
savedBb = bb;
bb = new ByteBuffer();
obj = reference.getRefersTo();
}
}
if (obj.isStream()) {
serDic((PdfDictionary) obj, bb, level - 1, serializedCache);
bb.append("$B");
if (level > 0) {
bb.append(sha512.digest(((PdfStream) obj).getBytes(false)));
}
} else if (obj.isDictionary()) {
serDic((PdfDictionary) obj, bb, level - 1, serializedCache);
} else if (obj.isArray()) {
serArray((PdfArray) obj, bb, level - 1, serializedCache);
} else if (obj.isString()) {
bb.append("$S").append(obj.toString());
} else if (obj.isName()) {
bb.append("$N").append(obj.toString());
} else {
// PdfNull case is also here
bb.append("$L").append(obj.toString());
}
if (savedBb != null) {
serializedCache.put(reference, bb.toByteArray());
savedBb.append(bb.getInternalBuffer(), 0, bb.size());
}
}
private void serDic(PdfDictionary dic, ByteBuffer bb, int level,
Map serializedCache) throws SelfReferenceException {
bb.append("$D");
if (level <= 0)
return;
for (PdfName key : dic.keySet()) {
if (isKeyRefersBack(dic, key)) {
continue;
}
serObject(key, bb, level, serializedCache);
serObject(dic.get(key, false), bb, level, serializedCache);
}
bb.append("$\\D");
}
private void serArray(PdfArray array, ByteBuffer bb, int level,
Map serializedCache) throws SelfReferenceException {
bb.append("$A");
if (level <= 0)
return;
for (int k = 0; k < array.size(); ++k) {
serObject(array.get(k, false), bb, level, serializedCache);
}
bb.append("$\\A");
}
private boolean isKeyRefersBack(PdfDictionary dic, PdfName key) {
// ignore recursive call
return key.equals(PdfName.P) && (dic.get(key).isIndirectReference() || dic.get(key).isDictionary())
|| key.equals(PdfName.Parent);
}
private static class SelfReferenceException extends Exception {
}
}
