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      1 // Copyright 2016 PDFium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
      6 
      7 #include "core/fpdfapi/parser/cpdf_linearized_header.h"
      8 
      9 #include <algorithm>
     10 #include <utility>
     11 
     12 #include "core/fpdfapi/parser/cpdf_array.h"
     13 #include "core/fpdfapi/parser/cpdf_dictionary.h"
     14 #include "core/fpdfapi/parser/cpdf_number.h"
     15 #include "third_party/base/ptr_util.h"
     16 
     17 namespace {
     18 
     19 template <class T>
     20 bool IsValidNumericDictionaryValue(const CPDF_Dictionary* pDict,
     21                                    const char* key,
     22                                    T min_value,
     23                                    bool must_exist = true) {
     24   if (!pDict->KeyExist(key))
     25     return !must_exist;
     26   const CPDF_Number* pNum = ToNumber(pDict->GetObjectFor(key));
     27   if (!pNum || !pNum->IsInteger())
     28     return false;
     29   const int raw_value = pNum->GetInteger();
     30   if (!pdfium::base::IsValueInRangeForNumericType<T>(raw_value))
     31     return false;
     32   return static_cast<T>(raw_value) >= min_value;
     33 }
     34 
     35 }  // namespace
     36 
     37 // static
     38 std::unique_ptr<CPDF_LinearizedHeader> CPDF_LinearizedHeader::CreateForObject(
     39     std::unique_ptr<CPDF_Object> pObj) {
     40   auto pDict = ToDictionary(std::move(pObj));
     41   if (!pDict || !pDict->KeyExist("Linearized") ||
     42       !IsValidNumericDictionaryValue<FX_FILESIZE>(pDict.get(), "L", 1) ||
     43       !IsValidNumericDictionaryValue<uint32_t>(pDict.get(), "P", 0, false) ||
     44       !IsValidNumericDictionaryValue<FX_FILESIZE>(pDict.get(), "T", 1) ||
     45       !IsValidNumericDictionaryValue<uint32_t>(pDict.get(), "N", 0) ||
     46       !IsValidNumericDictionaryValue<FX_FILESIZE>(pDict.get(), "E", 1) ||
     47       !IsValidNumericDictionaryValue<uint32_t>(pDict.get(), "O", 1))
     48     return nullptr;
     49   return pdfium::WrapUnique(new CPDF_LinearizedHeader(pDict.get()));
     50 }
     51 
     52 CPDF_LinearizedHeader::CPDF_LinearizedHeader(const CPDF_Dictionary* pDict) {
     53   m_szFileSize = pDict->GetIntegerFor("L");
     54   m_dwFirstPageNo = pDict->GetIntegerFor("P");
     55   m_szLastXRefOffset = pDict->GetIntegerFor("T");
     56   m_PageCount = pDict->GetIntegerFor("N");
     57   m_szFirstPageEndOffset = pDict->GetIntegerFor("E");
     58   m_FirstPageObjNum = pDict->GetIntegerFor("O");
     59   const CPDF_Array* pHintStreamRange = pDict->GetArrayFor("H");
     60   const size_t nHintStreamSize =
     61       pHintStreamRange ? pHintStreamRange->GetCount() : 0;
     62   if (nHintStreamSize == 2 || nHintStreamSize == 4) {
     63     m_szHintStart = std::max(pHintStreamRange->GetIntegerAt(0), 0);
     64     m_szHintLength = std::max(pHintStreamRange->GetIntegerAt(1), 0);
     65   }
     66 }
     67 
     68 CPDF_LinearizedHeader::~CPDF_LinearizedHeader() {}
     69 
     70 bool CPDF_LinearizedHeader::HasHintTable() const {
     71   return GetPageCount() > 1 && GetHintStart() > 0 && GetHintLength() > 0;
     72 }
     73