mirror of
https://github.com/JakubMelka/PDF4QT.git
synced 2025-06-05 21:59:17 +02:00
398 lines
16 KiB
C++
398 lines
16 KiB
C++
// MIT License
|
|
//
|
|
// Copyright (c) 2018-2025 Jakub Melka and Contributors
|
|
//
|
|
// Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
// of this software and associated documentation files (the "Software"), to deal
|
|
// in the Software without restriction, including without limitation the rights
|
|
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
// copies of the Software, and to permit persons to whom the Software is
|
|
// furnished to do so, subject to the following conditions:
|
|
//
|
|
// The above copyright notice and this permission notice shall be included in all
|
|
// copies or substantial portions of the Software.
|
|
//
|
|
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
|
|
// SOFTWARE.
|
|
|
|
#include "pdfxreftable.h"
|
|
#include "pdfconstants.h"
|
|
#include "pdfexception.h"
|
|
#include "pdfparser.h"
|
|
#include "pdfstreamfilters.h"
|
|
|
|
#include <QIODevice>
|
|
#include <QDataStream>
|
|
|
|
#include "pdfdbgheap.h"
|
|
|
|
#include <stack>
|
|
|
|
namespace pdf
|
|
{
|
|
|
|
void PDFXRefTable::readXRefTable(PDFParsingContext* context, const QByteArray& byteArray, PDFInteger startTableOffset)
|
|
{
|
|
PDFParser parser(byteArray, context, PDFParser::AllowStreams);
|
|
|
|
m_entries.clear();
|
|
|
|
std::set<PDFInteger> processedOffsets;
|
|
std::stack<PDFInteger> workSet;
|
|
workSet.push(startTableOffset);
|
|
|
|
while (!workSet.empty())
|
|
{
|
|
PDFInteger currentOffset = workSet.top();
|
|
workSet.pop();
|
|
|
|
// Check, if we have cyclical references between tables
|
|
if (processedOffsets.count(currentOffset))
|
|
{
|
|
// If cyclical reference occurs, do not report error, just ignore it.
|
|
continue;
|
|
}
|
|
else
|
|
{
|
|
processedOffsets.insert(currentOffset);
|
|
}
|
|
|
|
// Now, we are ready to scan the table. Seek to the start of the reference table.
|
|
parser.seek(currentOffset);
|
|
|
|
if (parser.fetchCommand(PDF_XREF_HEADER))
|
|
{
|
|
while (!parser.fetchCommand(PDF_XREF_TRAILER))
|
|
{
|
|
// Now, first number is start offset, second number is count of table items
|
|
PDFObject firstObject = parser.getObject();
|
|
PDFObject countObject = parser.getObject();
|
|
|
|
if (!firstObject.isInt() || !countObject.isInt())
|
|
{
|
|
throw PDFException(tr("Invalid format of reference table."));
|
|
}
|
|
|
|
PDFInteger firstObjectNumber = firstObject.getInteger();
|
|
PDFInteger count = countObject.getInteger();
|
|
|
|
const PDFInteger lastObjectIndex = firstObjectNumber + count - 1;
|
|
const PDFInteger desiredSize = lastObjectIndex + 1;
|
|
|
|
if (static_cast<PDFInteger>(m_entries.size()) < desiredSize)
|
|
{
|
|
m_entries.resize(desiredSize);
|
|
}
|
|
|
|
// Now, read the records
|
|
for (PDFInteger i = 0; i < count; ++i)
|
|
{
|
|
const PDFInteger objectNumber = firstObjectNumber + i;
|
|
|
|
PDFObject offset = parser.getObject();
|
|
PDFObject generation = parser.getObject();
|
|
|
|
bool occupied = parser.fetchCommand(PDF_XREF_OCCUPIED);
|
|
if (!occupied && !parser.fetchCommand(PDF_XREF_FREE))
|
|
{
|
|
throw PDFException(tr("Bad format of reference table entry."));
|
|
}
|
|
|
|
if (!offset.isInt() || !generation.isInt())
|
|
{
|
|
throw PDFException(tr("Bad format of reference table entry."));
|
|
}
|
|
|
|
if (static_cast<size_t>(objectNumber) >= m_entries.size())
|
|
{
|
|
throw PDFException(tr("Bad format of reference table entry."));
|
|
}
|
|
|
|
Entry entry;
|
|
if (occupied)
|
|
{
|
|
entry.reference = PDFObjectReference(objectNumber, generation.getInteger());
|
|
entry.offset = offset.getInteger();
|
|
entry.type = EntryType::Occupied;
|
|
}
|
|
|
|
if (m_entries[objectNumber].type == EntryType::Free)
|
|
{
|
|
m_entries[objectNumber] = std::move(entry);
|
|
}
|
|
}
|
|
}
|
|
|
|
PDFObject trailerDictionary = parser.getObject();
|
|
if (!trailerDictionary.isDictionary())
|
|
{
|
|
throw PDFException(tr("Trailer dictionary is invalid."));
|
|
}
|
|
|
|
// Now, we have scanned the table. If we didn't have a trailer dictionary yet, then
|
|
// try to load it. We must also check, that trailer dictionary is OK.
|
|
if (m_trailerDictionary.isNull())
|
|
{
|
|
m_trailerDictionary = trailerDictionary;
|
|
}
|
|
|
|
const PDFDictionary* dictionary = trailerDictionary.getDictionary();
|
|
if (dictionary->hasKey(PDF_XREF_TRAILER_PREVIOUS))
|
|
{
|
|
PDFObject previousOffset = dictionary->get(PDF_XREF_TRAILER_PREVIOUS);
|
|
|
|
if (!previousOffset.isInt())
|
|
{
|
|
throw PDFException(tr("Offset of previous reference table is invalid."));
|
|
}
|
|
|
|
workSet.push(previousOffset.getInteger());
|
|
}
|
|
|
|
const PDFObject& xrefstmObject = dictionary->get(PDF_XREF_TRAILER_XREFSTM);
|
|
if (xrefstmObject.isInt())
|
|
{
|
|
workSet.push(xrefstmObject.getInteger());
|
|
}
|
|
}
|
|
else
|
|
{
|
|
// Try to read cross-reference stream
|
|
PDFObject crossReferenceStreamObjectNumber = parser.getObject();
|
|
PDFObject crossReferenceStreamGeneration = parser.getObject();
|
|
|
|
if (!crossReferenceStreamObjectNumber.isInt() || !crossReferenceStreamGeneration.isInt())
|
|
{
|
|
throw PDFException(tr("Invalid format of reference table."));
|
|
}
|
|
|
|
if (!parser.fetchCommand(PDF_OBJECT_START_MARK))
|
|
{
|
|
throw PDFException(tr("Invalid format of reference table."));
|
|
}
|
|
|
|
PDFObject crossReferenceObject = parser.getObject();
|
|
|
|
if (!parser.fetchCommand(PDF_OBJECT_END_MARK))
|
|
{
|
|
throw PDFException(tr("Invalid format of reference table."));
|
|
}
|
|
|
|
if (crossReferenceObject.isStream())
|
|
{
|
|
const PDFStream* crossReferenceStream = crossReferenceObject.getStream();
|
|
const PDFDictionary* crossReferenceStreamDictionary = crossReferenceStream->getDictionary();
|
|
const PDFObject typeObject = crossReferenceStreamDictionary->get("Type");
|
|
if (typeObject.isName() && typeObject.getString() == "XRef")
|
|
{
|
|
PDFObject sizeObject = crossReferenceStreamDictionary->get("Size");
|
|
if (!sizeObject.isInt() || sizeObject.getInteger() < 0)
|
|
{
|
|
throw PDFException(tr("Invalid format of cross-reference stream."));
|
|
}
|
|
|
|
const PDFInteger desiredSize = sizeObject.getInteger();
|
|
if (static_cast<PDFInteger>(m_entries.size()) < desiredSize)
|
|
{
|
|
m_entries.resize(desiredSize);
|
|
}
|
|
|
|
PDFObject prevObject = crossReferenceStreamDictionary->get("Prev");
|
|
if (prevObject.isInt())
|
|
{
|
|
workSet.push(prevObject.getInteger());
|
|
}
|
|
|
|
// Do not overwrite trailer dictionary, if it was already loaded.
|
|
if (m_trailerDictionary.isNull())
|
|
{
|
|
m_trailerDictionary = crossReferenceObject;
|
|
}
|
|
|
|
auto readIntegerArray = [crossReferenceStreamDictionary](const char* key, auto defaultValues) -> std::vector<PDFInteger>
|
|
{
|
|
std::vector<PDFInteger> result;
|
|
|
|
const PDFObject& object = crossReferenceStreamDictionary->get(key);
|
|
if (object.isArray())
|
|
{
|
|
const PDFArray* array = object.getArray();
|
|
result.reserve(array->getCount());
|
|
|
|
for (size_t i = 0, count = array->getCount(); i < count; ++i)
|
|
{
|
|
const PDFObject& itemObject = array->getItem(i);
|
|
if (itemObject.isInt())
|
|
{
|
|
result.push_back(itemObject.getInteger());
|
|
}
|
|
else
|
|
{
|
|
throw PDFException(tr("Invalid format of cross-reference stream."));
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
result = defaultValues;
|
|
}
|
|
|
|
return result;
|
|
};
|
|
|
|
std::vector<PDFInteger> indexArray = readIntegerArray("Index", std::initializer_list<PDFInteger>{ PDFInteger(0), PDFInteger(desiredSize) });
|
|
std::vector<PDFInteger> wArray = readIntegerArray("W", std::vector<PDFInteger>());
|
|
|
|
if (wArray.size() != 3 || indexArray.empty() || (indexArray.size() % 2 != 0))
|
|
{
|
|
throw PDFException(tr("Invalid format of cross-reference stream."));
|
|
}
|
|
|
|
const int columnTypeBytes = wArray[0];
|
|
const int columnObjectNumberOrByteOffsetBytes = wArray[1];
|
|
const int columnGenerationNumberOrObjectIndexBytes = wArray[2];
|
|
const size_t blockCount = indexArray.size() / 2;
|
|
|
|
QByteArray data = PDFStreamFilterStorage::getDecodedStream(crossReferenceStream, nullptr);
|
|
QDataStream dataStream(&data, QIODevice::ReadOnly);
|
|
dataStream.setByteOrder(QDataStream::BigEndian);
|
|
|
|
auto readNumber = [&dataStream](int bytes, PDFInteger defaultValue) -> PDFInteger
|
|
{
|
|
if (bytes)
|
|
{
|
|
uint64_t value = 0;
|
|
|
|
while (bytes--)
|
|
{
|
|
uint8_t byte = 0;
|
|
dataStream >> byte;
|
|
value = (value << 8) + byte;
|
|
|
|
// Check, if stream is OK (we doesn't read past the end of the stream,
|
|
// data aren't corrupted etc.)
|
|
if (dataStream.status() != QDataStream::Ok)
|
|
{
|
|
throw PDFException(tr("Invalid format of cross-reference stream - not enough data in the stream."));
|
|
}
|
|
}
|
|
|
|
return static_cast<PDFInteger>(value);
|
|
}
|
|
return defaultValue;
|
|
};
|
|
|
|
for (size_t i = 0; i < blockCount; ++i)
|
|
{
|
|
PDFInteger firstObjectNumber = indexArray[2 * i];
|
|
PDFInteger count = indexArray[2 * i + 1];
|
|
|
|
const PDFInteger lastObjectIndex = firstObjectNumber + count - 1;
|
|
const PDFInteger currentDesiredSize = lastObjectIndex + 1;
|
|
|
|
if (static_cast<PDFInteger>(m_entries.size()) < currentDesiredSize)
|
|
{
|
|
m_entries.resize(currentDesiredSize);
|
|
}
|
|
|
|
for (PDFInteger objectNumber = firstObjectNumber; objectNumber <= lastObjectIndex; ++ objectNumber)
|
|
{
|
|
int itemType = readNumber(columnTypeBytes, 1);
|
|
int itemObjectNumberOfObjectStreamOrByteOffset = readNumber(columnObjectNumberOrByteOffsetBytes, 0);
|
|
int itemGenerationNumberOrObjectIndex = readNumber(columnGenerationNumberOrObjectIndexBytes, 0);
|
|
|
|
switch (itemType)
|
|
{
|
|
case 0:
|
|
// Free object
|
|
break;
|
|
|
|
case 1:
|
|
{
|
|
Entry entry;
|
|
entry.reference = PDFObjectReference(objectNumber, itemGenerationNumberOrObjectIndex);
|
|
entry.offset = itemObjectNumberOfObjectStreamOrByteOffset;
|
|
entry.type = EntryType::Occupied;
|
|
|
|
if (m_entries[objectNumber].type == EntryType::Free)
|
|
{
|
|
m_entries[objectNumber] = std::move(entry);
|
|
}
|
|
break;
|
|
}
|
|
|
|
case 2:
|
|
{
|
|
Entry entry;
|
|
entry.reference = PDFObjectReference(objectNumber, 0);
|
|
entry.objectStream = PDFObjectReference(itemObjectNumberOfObjectStreamOrByteOffset, 0);
|
|
entry.indexInObjectStream = itemGenerationNumberOrObjectIndex;
|
|
entry.type = EntryType::InObjectStream;
|
|
|
|
if (m_entries[objectNumber].type == EntryType::Free)
|
|
{
|
|
m_entries[objectNumber] = std::move(entry);
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
default:
|
|
// According to the specification, treat this object as null object
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
continue;
|
|
}
|
|
|
|
throw PDFException(tr("Invalid format of reference table."));
|
|
}
|
|
}
|
|
}
|
|
|
|
std::vector<PDFXRefTable::Entry> PDFXRefTable::getOccupiedEntries() const
|
|
{
|
|
std::vector<PDFXRefTable::Entry> result;
|
|
|
|
// Suppose majority of items are occupied
|
|
result.reserve(m_entries.size());
|
|
std::copy_if(m_entries.cbegin(), m_entries.cend(), std::back_inserter(result), [](const Entry& entry) { return entry.type == EntryType::Occupied; });
|
|
|
|
return result;
|
|
}
|
|
|
|
std::vector<PDFXRefTable::Entry> PDFXRefTable::getObjectStreamEntries() const
|
|
{
|
|
std::vector<PDFXRefTable::Entry> result;
|
|
|
|
// Suppose majority of items are occupied
|
|
result.reserve(m_entries.size());
|
|
std::copy_if(m_entries.cbegin(), m_entries.cend(), std::back_inserter(result), [](const Entry& entry) { return entry.type == EntryType::InObjectStream; });
|
|
|
|
return result;
|
|
}
|
|
|
|
const PDFXRefTable::Entry& PDFXRefTable::getEntry(PDFObjectReference reference) const
|
|
{
|
|
// We must also check generation number here. For this reason, we compare references of the entry at given position.
|
|
if (reference.objectNumber >= 0 && reference.objectNumber < static_cast<PDFInteger>(m_entries.size()) && m_entries[reference.objectNumber].reference == reference)
|
|
{
|
|
return m_entries[reference.objectNumber];
|
|
}
|
|
else
|
|
{
|
|
static Entry dummy;
|
|
return dummy;
|
|
}
|
|
}
|
|
|
|
} // namespace pdf
|