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Handling object reference streams

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This commit is contained in:
Jakub Melka
2019-07-01 12:29:57 +02:00
parent 8c130ca013
commit 4d782af971
7 changed files with 383 additions and 20 deletions
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109
PdfForQtLib/sources/pdfdocumentreader.cpp
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@ -21,6 +21,7 @@
#include "pdfxreftable.h"
#include "pdfexception.h"
#include "pdfparser.h"
#include "pdfstreamfilters.h"
#include <QFile>
@ -239,6 +240,7 @@ PDFDocument PDFDocumentReader::readFromBuffer(const QByteArray& buffer)
std::vector<PDFXRefTable::Entry> occupiedEntries = xrefTable.getOccupiedEntries();
// First, process regular objects
auto processEntry = [this, &getObject, &objectFetcher, &objects](const PDFXRefTable::Entry& entry)
{
Q_ASSERT(entry.type == PDFXRefTable::EntryType::Occupied);
@ -248,7 +250,10 @@ PDFDocument PDFDocumentReader::readFromBuffer(const QByteArray& buffer)
try
{
PDFParsingContext context(objectFetcher);
objects[entry.reference.objectNumber] = PDFObjectStorage::Entry(entry.reference.generation, getObject(&context, entry.offset, entry.reference));
PDFObject object = getObject(&context, entry.offset, entry.reference);
QMutexLocker lock(&m_mutex);
objects[entry.reference.objectNumber] = PDFObjectStorage::Entry(entry.reference.generation, object);
}
catch (PDFParserException exception)
{
@ -262,6 +267,108 @@ PDFDocument PDFDocumentReader::readFromBuffer(const QByteArray& buffer)
// Now, we are ready to scan all objects
std::for_each(std::execution::parallel_policy(), occupiedEntries.cbegin(), occupiedEntries.cend(), processEntry);
// Then process object streams
std::vector<PDFXRefTable::Entry> objectStreamEntries = xrefTable.getObjectStreamEntries();
std::set<PDFObjectReference> objectStreams;
for (const PDFXRefTable::Entry& entry : objectStreamEntries)
{
Q_ASSERT(entry.type == PDFXRefTable::EntryType::InObjectStream);
objectStreams.insert(entry.objectStream);
}
auto processObjectStream = [this, &getObject, &objectFetcher, &objects, &objectStreamEntries] (const PDFObjectReference& objectStreamReference)
{
if (!m_successfull)
{
return;
}
try
{
PDFParsingContext context(objectFetcher);
if (objectStreamReference.objectNumber >= static_cast<PDFInteger>(objects.size()))
{
throw PDFParserException(PDFTranslationContext::tr("Object stream %1 not found.").arg(objectStreamReference.objectNumber));
}
const PDFObject& object = objects[objectStreamReference.objectNumber].object;
if (!object.isStream())
{
throw PDFParserException(PDFTranslationContext::tr("Object stream %1 is invalid.").arg(objectStreamReference.objectNumber));
}
const PDFStream* objectStream = object.getStream();
const PDFDictionary* objectStreamDictionary = objectStream->getDictionary();
const PDFObject& objectStreamType = objectStreamDictionary->get("Type");
if (!objectStreamType.isName() || objectStreamType.getString() != "ObjStm")
{
throw PDFParserException(PDFTranslationContext::tr("Object stream %1 is invalid.").arg(objectStreamReference.objectNumber));
}
const PDFObject& nObject = objectStreamDictionary->get("N");
const PDFObject& firstObject = objectStreamDictionary->get("First");
if (!nObject.isInt() || !firstObject.isInt())
{
throw PDFParserException(PDFTranslationContext::tr("Object stream %1 is invalid.").arg(objectStreamReference.objectNumber));
}
// Number of objects in object stream dictionary
const PDFInteger n = nObject.getInteger();
const PDFInteger first = firstObject.getInteger();
QByteArray objectStreamData = PDFStreamFilterStorage::getDecodedStream(objectStream);
PDFParsingContext::PDFParsingContextGuard guard(&context, objectStreamReference);
PDFParser parser(objectStreamData, &context, PDFParser::AllowStreams);
std::vector<std::pair<PDFInteger, PDFInteger>> objectNumberAndOffset;
objectNumberAndOffset.reserve(n);
for (PDFInteger i = 0; i < n; ++i)
{
PDFObject currentObjectNumber = parser.getObject();
PDFObject currentOffset = parser.getObject();
if (!currentObjectNumber.isInt() || !currentOffset.isInt())
{
throw PDFParserException(PDFTranslationContext::tr("Object stream %1 is invalid.").arg(objectStreamReference.objectNumber));
}
const PDFInteger objectNumber = currentObjectNumber.getInteger();
const PDFInteger offset = currentOffset.getInteger() + first;
objectNumberAndOffset.emplace_back(objectNumber, offset);
}
for (size_t i = 0; i < objectNumberAndOffset.size(); ++i)
{
const PDFInteger objectNumber = objectNumberAndOffset[i].first;
const PDFInteger offset = objectNumberAndOffset[i].second;
parser.seek(offset);
PDFObject object = parser.getObject();
auto predicate = [objectNumber, objectStreamReference](const PDFXRefTable::Entry& entry) -> bool { return entry.reference.objectNumber == objectNumber && entry.objectStream == objectStreamReference; };
if (std::find_if(objectStreamEntries.cbegin(), objectStreamEntries.cend(), predicate) != objectStreamEntries.cend())
{
QMutexLocker lock(&m_mutex);
objects[objectNumber].object = qMove(object);
}
else
{
throw PDFParserException(PDFTranslationContext::tr("Object stream %1 is invalid.").arg(objectStreamReference.objectNumber));
}
}
}
catch (PDFParserException exception)
{
QMutexLocker lock(&m_mutex);
m_successfull = false;
m_errorMessage = exception.getMessage();
}
};
// Now, we are ready to scan all object streams
std::for_each(std::execution::parallel_policy(), objectStreams.cbegin(), objectStreams.cend(), processObjectStream);
PDFObjectStorage storage(std::move(objects), PDFObject(xrefTable.getTrailerDictionary()));
return PDFDocument(std::move(storage));
}