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// Copyright 2016 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
#include "core/fpdfapi/parser/cpdf_linearized_header.h"
#include <algorithm>
#include <limits>
#include <utility>
#include "core/fpdfapi/parser/cpdf_array.h"
#include "core/fpdfapi/parser/cpdf_dictionary.h"
#include "core/fpdfapi/parser/cpdf_number.h"
#include "core/fpdfapi/parser/cpdf_syntax_parser.h"
#include "third_party/base/ptr_util.h"
namespace {
constexpr FX_FILESIZE kLinearizedHeaderOffset = 9;
constexpr size_t kMaxInt = static_cast<size_t>(std::numeric_limits<int>::max());
template <class T>
bool IsValidNumericDictionaryValue(const CPDF_Dictionary* pDict,
const char* key,
T min_value,
bool must_exist = true) {
if (!pDict->KeyExist(key))
return !must_exist;
const CPDF_Number* pNum = ToNumber(pDict->GetObjectFor(key));
if (!pNum || !pNum->IsInteger())
return false;
const int raw_value = pNum->GetInteger();
if (!pdfium::base::IsValueInRangeForNumericType<T>(raw_value))
return false;
return static_cast<T>(raw_value) >= min_value;
}
bool IsLinearizedHeaderValid(const CPDF_LinearizedHeader* header,
FX_FILESIZE document_size) {
ASSERT(header);
return header->GetFileSize() == document_size &&
header->GetFirstPageNo() < kMaxInt &&
header->GetFirstPageNo() < header->GetPageCount() &&
header->GetMainXRefTableFirstEntryOffset() < document_size &&
header->GetFirstPageEndOffset() < document_size &&
header->GetLastXRefOffset() < document_size &&
header->GetHintStart() < document_size;
}
} // namespace
// static
std::unique_ptr<CPDF_LinearizedHeader> CPDF_LinearizedHeader::Parse(
CPDF_SyntaxParser* parser) {
parser->SetPos(kLinearizedHeaderOffset);
const auto pDict = ToDictionary(
parser->GetIndirectObject(nullptr, CPDF_SyntaxParser::ParseType::kLoose));
if (!pDict || !pDict->KeyExist("Linearized") ||
!IsValidNumericDictionaryValue<FX_FILESIZE>(pDict.get(), "L", 1) ||
!IsValidNumericDictionaryValue<uint32_t>(pDict.get(), "P", 0, false) ||
!IsValidNumericDictionaryValue<FX_FILESIZE>(pDict.get(), "T", 1) ||
!IsValidNumericDictionaryValue<uint32_t>(pDict.get(), "N", 1) ||
!IsValidNumericDictionaryValue<FX_FILESIZE>(pDict.get(), "E", 1) ||
!IsValidNumericDictionaryValue<uint32_t>(pDict.get(), "O", 1)) {
return nullptr;
}
// Move parser to the start of the xref table for the documents first page.
// (skpping endobj keyword)
if (parser->GetNextWord(nullptr) != "endobj")
return nullptr;
auto result = pdfium::WrapUnique(
new CPDF_LinearizedHeader(pDict.get(), parser->GetPos()));
if (!IsLinearizedHeaderValid(result.get(), parser->GetDocumentSize()))
return nullptr;
return result;
}
CPDF_LinearizedHeader::CPDF_LinearizedHeader(const CPDF_Dictionary* pDict,
FX_FILESIZE szLastXRefOffset)
: m_szFileSize(pDict->GetIntegerFor("L")),
m_dwFirstPageNo(pDict->GetIntegerFor("P")),
m_szMainXRefTableFirstEntryOffset(pDict->GetIntegerFor("T")),
m_PageCount(pDict->GetIntegerFor("N")),
m_szFirstPageEndOffset(pDict->GetIntegerFor("E")),
m_FirstPageObjNum(pDict->GetIntegerFor("O")),
m_szLastXRefOffset(szLastXRefOffset) {
const CPDF_Array* pHintStreamRange = pDict->GetArrayFor("H");
const size_t nHintStreamSize =
pHintStreamRange ? pHintStreamRange->GetCount() : 0;
if (nHintStreamSize == 2 || nHintStreamSize == 4) {
m_szHintStart = std::max(pHintStreamRange->GetIntegerAt(0), 0);
const FX_SAFE_UINT32 safe_hint_length = pHintStreamRange->GetIntegerAt(1);
if (safe_hint_length.IsValid())
m_HintLength = safe_hint_length.ValueOrDie();
}
}
CPDF_LinearizedHeader::~CPDF_LinearizedHeader() {}
bool CPDF_LinearizedHeader::HasHintTable() const {
return GetPageCount() > 1 && GetHintStart() > 0 && GetHintLength() > 0;
}
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