Reland of Unify some code

Unify some code
Move parsing of linearized header into separate CPDF_Linearized class.

Original review:
https://codereview.chromium.org/2466023002/

Revert review:
https://codereview.chromium.org/2474283005/

Revert reason was:
Breaking the chrome roll.
See https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_rel_ng/builds/331856
___

Added Fix for fuzzers.

Review-Url: https://codereview.chromium.org/2477213003

11 files changed, 208 insertions, 202 deletions

diff --git a/core/fpdfapi/parser/cpdf_data_avail.cpp b/core/fpdfapi/parser/cpdf_data_avail.cpp
index c4ed95e17f..e6d2c61ad3 100644
--- a/core/fpdfapi/parser/cpdf_data_avail.cpp
+++ b/core/fpdfapi/parser/cpdf_data_avail.cpp
@@ -15,6 +15,7 @@
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fpdfapi/parser/cpdf_document.h"
 #include "core/fpdfapi/parser/cpdf_hint_tables.h"
+#include "core/fpdfapi/parser/cpdf_linearized.h"
 #include "core/fpdfapi/parser/cpdf_name.h"
 #include "core/fpdfapi/parser/cpdf_number.h"
 #include "core/fpdfapi/parser/cpdf_reference.h"
@@ -43,7 +44,6 @@ CPDF_DataAvail::CPDF_DataAvail(FileAvail* pFileAvail,
   m_dwCurrentOffset = 0;
   m_dwXRefOffset = 0;
   m_bufferOffset = 0;
-  m_dwFirstPageNo = 0;
   m_bufferSize = 0;
   m_PagesObjNum = 0;
   m_dwCurrentXRefSteam = 0;
@@ -56,7 +56,6 @@ CPDF_DataAvail::CPDF_DataAvail(FileAvail* pFileAvail,
   m_bDocAvail = false;
   m_bMainXRefLoadTried = false;
   m_bDocAvail = false;
-  m_bLinearized = false;
   m_bPagesLoad = false;
   m_bPagesTreeLoad = false;
   m_bMainXRefLoadedOK = false;
@@ -66,7 +65,6 @@ CPDF_DataAvail::CPDF_DataAvail(FileAvail* pFileAvail,
   m_bPageLoadedOK = false;
   m_bNeedDownLoadResource = false;
   m_bLinearizedFormParamLoad = false;
-  m_pLinearized = nullptr;
   m_pRoot = nullptr;
   m_pTrailer = nullptr;
   m_pCurrentParser = nullptr;
@@ -83,9 +81,6 @@ CPDF_DataAvail::CPDF_DataAvail(FileAvail* pFileAvail,
 
 CPDF_DataAvail::~CPDF_DataAvail() {
   m_pHintTables.reset();
-  delete m_pLinearized;
-  delete m_pRoot;
-  delete m_pTrailer;
 
   for (CPDF_Object* pObject : m_arrayAcroforms)
     delete pObject;
@@ -613,48 +608,27 @@ bool CPDF_DataAvail::CheckHeader(DownloadHints* pHints) {
 }
 
 bool CPDF_DataAvail::CheckFirstPage(DownloadHints* pHints) {
-  CPDF_Dictionary* pDict = m_pLinearized->GetDict();
-  CPDF_Object* pEndOffSet = pDict ? pDict->GetObjectFor("E") : nullptr;
-  if (!pEndOffSet) {
-    m_docStatus = PDF_DATAAVAIL_ERROR;
-    return false;
-  }
-
-  CPDF_Object* pXRefOffset = pDict ? pDict->GetObjectFor("T") : nullptr;
-  if (!pXRefOffset) {
-    m_docStatus = PDF_DATAAVAIL_ERROR;
-    return false;
-  }
-
-  CPDF_Object* pFileLen = pDict ? pDict->GetObjectFor("L") : nullptr;
-  if (!pFileLen) {
+  if (!m_pLinearized->GetFirstPageEndOffset() ||
+      !m_pLinearized->GetFileSize() || !m_pLinearized->GetLastXRefOffset()) {
     m_docStatus = PDF_DATAAVAIL_ERROR;
     return false;
   }
 
   bool bNeedDownLoad = false;
-  if (pEndOffSet->IsNumber()) {
-    uint32_t dwEnd = pEndOffSet->GetInteger();
-    dwEnd += 512;
-    if ((FX_FILESIZE)dwEnd > m_dwFileLen)
-      dwEnd = (uint32_t)m_dwFileLen;
-
-    int32_t iStartPos = (int32_t)(m_dwFileLen > 1024 ? 1024 : m_dwFileLen);
-    int32_t iSize = dwEnd > 1024 ? dwEnd - 1024 : 0;
-    if (!m_pFileAvail->IsDataAvail(iStartPos, iSize)) {
-      pHints->AddSegment(iStartPos, iSize);
-      bNeedDownLoad = true;
-    }
-  }
+  uint32_t dwEnd = m_pLinearized->GetFirstPageEndOffset();
+  dwEnd += 512;
+  if ((FX_FILESIZE)dwEnd > m_dwFileLen)
+    dwEnd = (uint32_t)m_dwFileLen;
 
-  m_dwLastXRefOffset = 0;
-  FX_FILESIZE dwFileLen = 0;
-  if (pXRefOffset->IsNumber())
-    m_dwLastXRefOffset = pXRefOffset->GetInteger();
-
-  if (pFileLen->IsNumber())
-    dwFileLen = pFileLen->GetInteger();
+  int32_t iStartPos = (int32_t)(m_dwFileLen > 1024 ? 1024 : m_dwFileLen);
+  int32_t iSize = dwEnd > 1024 ? dwEnd - 1024 : 0;
+  if (!m_pFileAvail->IsDataAvail(iStartPos, iSize)) {
+    pHints->AddSegment(iStartPos, iSize);
+    bNeedDownLoad = true;
+  }
 
+  m_dwLastXRefOffset = m_pLinearized->GetLastXRefOffset();
+  FX_FILESIZE dwFileLen = m_pLinearized->GetFileSize();
   if (!m_pFileAvail->IsDataAvail(m_dwLastXRefOffset,
                                  (uint32_t)(dwFileLen - m_dwLastXRefOffset))) {
     if (m_docStatus == PDF_DATAAVAIL_FIRSTPAGE) {
@@ -702,52 +676,17 @@ bool CPDF_DataAvail::IsDataAvail(FX_FILESIZE offset,
 }
 
 bool CPDF_DataAvail::CheckHintTables(DownloadHints* pHints) {
-  CPDF_Dictionary* pDict = m_pLinearized->GetDict();
-  if (!pDict) {
-    m_docStatus = PDF_DATAAVAIL_ERROR;
-    return false;
-  }
-
-  // The actual value is not required here, but validate its existence and type.
-  CPDF_Number* pFirstPage = ToNumber(pDict->GetDirectObjectFor("O"));
-  if (!pFirstPage || !pFirstPage->IsInteger()) {
-    m_docStatus = PDF_DATAAVAIL_ERROR;
-    return false;
-  }
-
-  CPDF_Number* pPageCount = ToNumber(pDict->GetDirectObjectFor("N"));
-  if (!pPageCount || !pPageCount->IsInteger()) {
-    m_docStatus = PDF_DATAAVAIL_ERROR;
-    return false;
-  }
-
-  int nPageCount = pPageCount->GetInteger();
-  if (nPageCount <= 1) {
+  if (m_pLinearized->GetPageCount() <= 1) {
     m_docStatus = PDF_DATAAVAIL_DONE;
     return true;
   }
-
-  CPDF_Array* pHintStreamRange = pDict->GetArrayFor("H");
-  size_t nHintStreamSize = pHintStreamRange ? pHintStreamRange->GetCount() : 0;
-  if (nHintStreamSize != 2 && nHintStreamSize != 4) {
+  if (!m_pLinearized->HasHintTable()) {
     m_docStatus = PDF_DATAAVAIL_ERROR;
     return false;
   }
 
-  for (const CPDF_Object* pArrayObject : *pHintStreamRange) {
-    const CPDF_Number* pNumber = ToNumber(pArrayObject->GetDirect());
-    if (!pNumber || !pNumber->IsInteger()) {
-      m_docStatus = PDF_DATAAVAIL_ERROR;
-      return false;
-    }
-  }
-
-  FX_FILESIZE szHintStart = pHintStreamRange->GetIntegerAt(0);
-  FX_FILESIZE szHintLength = pHintStreamRange->GetIntegerAt(1);
-  if (szHintStart < 0 || szHintLength <= 0) {
-    m_docStatus = PDF_DATAAVAIL_ERROR;
-    return false;
-  }
+  FX_FILESIZE szHintStart = m_pLinearized->GetHintStart();
+  FX_FILESIZE szHintLength = m_pLinearized->GetHintLength();
 
   if (!IsDataAvail(szHintStart, szHintLength, pHints))
     return false;
@@ -755,7 +694,7 @@ bool CPDF_DataAvail::CheckHintTables(DownloadHints* pHints) {
   m_syntaxParser.InitParser(m_pFileRead, m_dwHeaderOffset);
 
   std::unique_ptr<CPDF_HintTables> pHintTables(
-      new CPDF_HintTables(this, pDict));
+      new CPDF_HintTables(this, m_pLinearized.get()));
   std::unique_ptr<CPDF_Object> pHintStream(
       ParseIndirectObjectAt(szHintStart, 0));
   CPDF_Stream* pStream = ToStream(pHintStream.get());
@@ -819,12 +758,12 @@ CPDF_DataAvail::DocLinearizationStatus CPDF_DataAvail::IsLinearizedPDF() {
 }
 
 bool CPDF_DataAvail::IsLinearized() {
-  return m_bLinearized;
+  return !!m_pLinearized;
 }
 
 bool CPDF_DataAvail::IsLinearizedFile(uint8_t* pData, uint32_t dwLen) {
   if (m_pLinearized)
-    return m_bLinearized;
+    return true;
 
   ScopedFileStream file(FX_CreateMemoryStream(pData, (size_t)dwLen, false));
 
@@ -844,27 +783,13 @@ bool CPDF_DataAvail::IsLinearizedFile(uint8_t* pData, uint32_t dwLen) {
     return false;
 
   uint32_t objnum = FXSYS_atoui(wordObjNum.c_str());
-  m_pLinearized =
-      ParseIndirectObjectAt(m_syntaxParser.m_HeaderOffset + 9, objnum);
-  if (!m_pLinearized)
-    return false;
-
-  CPDF_Dictionary* pDict = m_pLinearized->GetDict();
-  if (!pDict || !pDict->GetObjectFor("Linearized"))
+  m_pLinearized = CPDF_Linearized::CreateForObject(pdfium::WrapUnique(
+      ParseIndirectObjectAt(m_syntaxParser.m_HeaderOffset + 9, objnum)));
+  if (!m_pLinearized ||
+      m_pLinearized->GetFileSize() != m_pFileRead->GetSize()) {
+    m_pLinearized.reset();
     return false;
-
-  CPDF_Object* pLen = pDict->GetObjectFor("L");
-  if (!pLen)
-    return false;
-
-  if ((FX_FILESIZE)pLen->GetInteger() != m_pFileRead->GetSize())
-    return false;
-
-  m_bLinearized = true;
-
-  if (CPDF_Number* pNo = ToNumber(pDict->GetObjectFor("P")))
-    m_dwFirstPageNo = pNo->GetInteger();
-
+  }
   return true;
 }
 
@@ -1600,8 +1525,8 @@ CPDF_DataAvail::DocAvailStatus CPDF_DataAvail::IsPageAvail(
   if (pdfium::ContainsKey(m_pagesLoadState, dwPage))
     return DataAvailable;
 
-  if (m_bLinearized) {
-    if (dwPage == m_dwFirstPageNo) {
+  if (m_pLinearized) {
+    if (dwPage == m_pLinearized->GetFirstPageNo()) {
       DocAvailStatus nRet = CheckLinearizedFirstPage(dwPage, pHints);
       if (nRet == DataAvailable)
         m_pagesLoadState.insert(dwPage);
@@ -1731,11 +1656,8 @@ void CPDF_DataAvail::GetLinearizedMainXRefInfo(FX_FILESIZE* pPos,
 }
 
 int CPDF_DataAvail::GetPageCount() const {
-  if (m_pLinearized) {
-    CPDF_Dictionary* pDict = m_pLinearized->GetDict();
-    CPDF_Object* pObj = pDict ? pDict->GetDirectObjectFor("N") : nullptr;
-    return pObj ? pObj->GetInteger() : 0;
-  }
+  if (m_pLinearized)
+    return m_pLinearized->GetPageCount();
   return m_pDocument ? m_pDocument->GetPageCount() : 0;
 }
 
@@ -1748,10 +1670,7 @@ CPDF_Dictionary* CPDF_DataAvail::GetPage(int index) {
   if (!m_pLinearized || !m_pHintTables)
     return nullptr;
 
-  CPDF_Dictionary* pDict = m_pLinearized->GetDict();
-  CPDF_Object* pObj = pDict ? pDict->GetDirectObjectFor("P") : nullptr;
-  int firstPageNum = pObj ? pObj->GetInteger() : 0;
-  if (index == firstPageNum)
+  if (index == static_cast<int>(m_pLinearized->GetFirstPageNo()))
     return nullptr;
   FX_FILESIZE szPageStartPos = 0;
   FX_FILESIZE szPageLength = 0;
diff --git a/core/fpdfapi/parser/cpdf_data_avail.h b/core/fpdfapi/parser/cpdf_data_avail.h
index 0a8716a498..bff9f2943b 100644
--- a/core/fpdfapi/parser/cpdf_data_avail.h
+++ b/core/fpdfapi/parser/cpdf_data_avail.h
@@ -16,6 +16,7 @@
 class CPDF_Dictionary;
 class CPDF_HintTables;
 class CPDF_IndirectObjectHolder;
+class CPDF_Linearized;
 class CPDF_Parser;
 
 enum PDF_DATAAVAIL_STATUS {
@@ -199,7 +200,7 @@ class CPDF_DataAvail final {
   CPDF_Object* m_pRoot;
   uint32_t m_dwRootObjNum;
   uint32_t m_dwInfoObjNum;
-  CPDF_Object* m_pLinearized;
+  std::unique_ptr<CPDF_Linearized> m_pLinearized;
   CPDF_Object* m_pTrailer;
   bool m_bDocAvail;
   FX_FILESIZE m_dwHeaderOffset;
@@ -220,8 +221,6 @@ class CPDF_DataAvail final {
   CFX_ArrayTemplate<uint32_t> m_XRefStreamList;
   CFX_ArrayTemplate<uint32_t> m_PageObjList;
   uint32_t m_PagesObjNum;
-  bool m_bLinearized;
-  uint32_t m_dwFirstPageNo;
   bool m_bLinearedDataOK;
   bool m_bMainXRefLoadTried;
   bool m_bMainXRefLoadedOK;
diff --git a/core/fpdfapi/parser/cpdf_document.cpp b/core/fpdfapi/parser/cpdf_document.cpp
index 8e181de97c..d9ffc0b28a 100644
--- a/core/fpdfapi/parser/cpdf_document.cpp
+++ b/core/fpdfapi/parser/cpdf_document.cpp
@@ -17,6 +17,7 @@
 #include "core/fpdfapi/page/pageint.h"
 #include "core/fpdfapi/parser/cpdf_array.h"
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
+#include "core/fpdfapi/parser/cpdf_linearized.h"
 #include "core/fpdfapi/parser/cpdf_number.h"
 #include "core/fpdfapi/parser/cpdf_parser.h"
 #include "core/fpdfapi/parser/cpdf_reference.h"
@@ -378,23 +379,13 @@ void CPDF_Document::LoadDoc() {
   m_PageList.SetSize(RetrievePageCount());
 }
 
-void CPDF_Document::LoadLinearizedDoc(CPDF_Dictionary* pLinearizationParams) {
+void CPDF_Document::LoadLinearizedDoc(
+    const CPDF_Linearized* pLinearizationParams) {
   m_bLinearized = true;
   LoadDocInternal();
-
-  uint32_t dwPageCount = 0;
-  CPDF_Object* pCount = pLinearizationParams->GetObjectFor("N");
-  if (ToNumber(pCount))
-    dwPageCount = pCount->GetInteger();
-  m_PageList.SetSize(dwPageCount);
-
-  CPDF_Object* pNo = pLinearizationParams->GetObjectFor("P");
-  if (ToNumber(pNo))
-    m_iFirstPageNo = pNo->GetInteger();
-
-  CPDF_Object* pObjNum = pLinearizationParams->GetObjectFor("O");
-  if (ToNumber(pObjNum))
-    m_dwFirstPageObjNum = pObjNum->GetInteger();
+  m_PageList.SetSize(pLinearizationParams->GetPageCount());
+  m_iFirstPageNo = pLinearizationParams->GetFirstPageNo();
+  m_dwFirstPageObjNum = pLinearizationParams->GetFirstPageObjNum();
 }
 
 void CPDF_Document::LoadPages() {
diff --git a/core/fpdfapi/parser/cpdf_document.h b/core/fpdfapi/parser/cpdf_document.h
index 0a99e42c3f..1b18015200 100644
--- a/core/fpdfapi/parser/cpdf_document.h
+++ b/core/fpdfapi/parser/cpdf_document.h
@@ -26,6 +26,7 @@ class CPDF_Font;
 class CPDF_FontEncoding;
 class CPDF_IccProfile;
 class CPDF_Image;
+class CPDF_Linearized;
 class CPDF_Parser;
 class CPDF_Pattern;
 class CPDF_StreamAcc;
@@ -85,7 +86,7 @@ class CPDF_Document : public CPDF_IndirectObjectHolder {
   CPDF_IccProfile* LoadIccProfile(CPDF_Stream* pStream);
 
   void LoadDoc();
-  void LoadLinearizedDoc(CPDF_Dictionary* pLinearizationParams);
+  void LoadLinearizedDoc(const CPDF_Linearized* pLinearizationParams);
   void LoadPages();
 
   void CreateNewDoc();
diff --git a/core/fpdfapi/parser/cpdf_document_unittest.cpp b/core/fpdfapi/parser/cpdf_document_unittest.cpp
index 16d0ade069..e20a5a1d1d 100644
--- a/core/fpdfapi/parser/cpdf_document_unittest.cpp
+++ b/core/fpdfapi/parser/cpdf_document_unittest.cpp
@@ -9,15 +9,13 @@
 #include "core/fpdfapi/cpdf_modulemgr.h"
 #include "core/fpdfapi/parser/cpdf_array.h"
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
+#include "core/fpdfapi/parser/cpdf_linearized.h"
 #include "core/fpdfapi/parser/cpdf_parser.h"
 #include "core/fxcrt/fx_memory.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
-using ScopedDictionary =
-    std::unique_ptr<CPDF_Dictionary, ReleaseDeleter<CPDF_Dictionary>>;
-
 CPDF_Dictionary* CreatePageTreeNode(CPDF_Array* kids,
                                     CPDF_Document* pDoc,
                                     int count) {
@@ -77,6 +75,11 @@ class CPDF_TestDocumentForPages : public CPDF_Document {
  private:
   std::unique_ptr<CPDF_Dictionary> m_pOwnedRootDict;
 };
+
+class TestLinearized : public CPDF_Linearized {
+ public:
+  explicit TestLinearized(CPDF_Dictionary* dict) : CPDF_Linearized(dict) {}
+};
 }  // namespace
 
 class cpdf_document_test : public testing::Test {
@@ -142,10 +145,12 @@ TEST_F(cpdf_document_test, UseCachedPageObjNumIfHaveNotPagesDict) {
   // can be not exists in this case.
   // (case, when hint table is used to page check in CPDF_DataAvail).
   CPDF_Document document(pdfium::MakeUnique<CPDF_Parser>());
-  std::unique_ptr<CPDF_Dictionary> dict(new CPDF_Dictionary());
+  auto dict = pdfium::MakeUnique<CPDF_Dictionary>();
+  dict->SetBooleanFor("Linearized", true);
   const int page_count = 100;
   dict->SetIntegerFor("N", page_count);
-  document.LoadLinearizedDoc(dict.get());
+  TestLinearized linearized(dict.get());
+  document.LoadLinearizedDoc(&linearized);
   ASSERT_EQ(page_count, document.GetPageCount());
   CPDF_Object* page_stub = new CPDF_Dictionary();
   const uint32_t obj_num = document.AddIndirectObject(page_stub);
diff --git a/core/fpdfapi/parser/cpdf_hint_tables.cpp b/core/fpdfapi/parser/cpdf_hint_tables.cpp
index 045b94cac5..bbc57dace9 100644
--- a/core/fpdfapi/parser/cpdf_hint_tables.cpp
+++ b/core/fpdfapi/parser/cpdf_hint_tables.cpp
@@ -12,6 +12,7 @@
 #include "core/fpdfapi/parser/cpdf_data_avail.h"
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fpdfapi/parser/cpdf_document.h"
+#include "core/fpdfapi/parser/cpdf_linearized.h"
 #include "core/fpdfapi/parser/cpdf_stream.h"
 #include "core/fpdfapi/parser/cpdf_stream_acc.h"
 #include "core/fxcrt/fx_safe_types.h"
@@ -34,12 +35,12 @@ bool IsValidPageOffsetHintTableBitCount(uint32_t bits) {
 }  // namespace
 
 CPDF_HintTables::CPDF_HintTables(CPDF_DataAvail* pDataAvail,
-                                 CPDF_Dictionary* pLinearized)
+                                 CPDF_Linearized* pLinearized)
     : m_pDataAvail(pDataAvail),
-      m_pLinearizedDict(pLinearized),
+      m_pLinearized(pLinearized),
       m_nFirstPageSharedObjs(0),
       m_szFirstPageObjOffset(0) {
-  ASSERT(m_pLinearizedDict);
+  ASSERT(m_pLinearized);
 }
 
 CPDF_HintTables::~CPDF_HintTables() {}
@@ -487,38 +488,25 @@ bool CPDF_HintTables::LoadHintStream(CPDF_Stream* pHintStream) {
 }
 
 int CPDF_HintTables::GetEndOfFirstPageOffset() const {
-  CPDF_Object* pOffsetE = m_pLinearizedDict->GetDirectObjectFor("E");
-  return pOffsetE ? pOffsetE->GetInteger() : -1;
+  return static_cast<int>(m_pLinearized->GetFirstPageEndOffset());
 }
 
 int CPDF_HintTables::GetNumberOfPages() const {
-  CPDF_Object* pPageNum = m_pLinearizedDict->GetDirectObjectFor("N");
-  return pPageNum ? pPageNum->GetInteger() : 0;
+  return static_cast<int>(m_pLinearized->GetPageCount());
 }
 
 int CPDF_HintTables::GetFirstPageObjectNumber() const {
-  CPDF_Object* pFirstPageObj = m_pLinearizedDict->GetDirectObjectFor("O");
-  return pFirstPageObj ? pFirstPageObj->GetInteger() : -1;
+  return static_cast<int>(m_pLinearized->GetFirstPageObjNum());
 }
 
 int CPDF_HintTables::GetFirstPageNumber() const {
-  CPDF_Object* pFirstPageNum = m_pLinearizedDict->GetDirectObjectFor("P");
-  return pFirstPageNum ? pFirstPageNum->GetInteger() : 0;
+  return static_cast<int>(m_pLinearized->GetFirstPageNo());
 }
 
 int CPDF_HintTables::ReadPrimaryHintStreamOffset() const {
-  return ReadPrimaryHintStream(0);
+  return static_cast<int>(m_pLinearized->GetHintStart());
 }
 
 int CPDF_HintTables::ReadPrimaryHintStreamLength() const {
-  return ReadPrimaryHintStream(1);
-}
-
-int CPDF_HintTables::ReadPrimaryHintStream(int index) const {
-  CPDF_Array* pRange = m_pLinearizedDict->GetArrayFor("H");
-  if (!pRange)
-    return -1;
-
-  CPDF_Object* pStreamLen = pRange->GetDirectObjectAt(index);
-  return pStreamLen ? pStreamLen->GetInteger() : -1;
+  return static_cast<int>(m_pLinearized->GetHintLength());
 }
diff --git a/core/fpdfapi/parser/cpdf_hint_tables.h b/core/fpdfapi/parser/cpdf_hint_tables.h
index 84f48cf41f..68b5059b05 100644
--- a/core/fpdfapi/parser/cpdf_hint_tables.h
+++ b/core/fpdfapi/parser/cpdf_hint_tables.h
@@ -14,12 +14,12 @@
 #include "core/fxcrt/fx_stream.h"
 
 class CFX_BitStream;
-class CPDF_Dictionary;
+class CPDF_Linearized;
 class CPDF_Stream;
 
 class CPDF_HintTables {
  public:
-  CPDF_HintTables(CPDF_DataAvail* pDataAvail, CPDF_Dictionary* pLinearized);
+  CPDF_HintTables(CPDF_DataAvail* pDataAvail, CPDF_Linearized* pLinearized);
   virtual ~CPDF_HintTables();
 
   bool GetPagePos(uint32_t index,
@@ -46,9 +46,6 @@ class CPDF_HintTables {
   virtual int ReadPrimaryHintStreamOffset() const;
   virtual int ReadPrimaryHintStreamLength() const;
 
-  // Helper for the ReadPrimaryHintStream methods above.
-  int ReadPrimaryHintStream(int index) const;
-
   uint32_t GetItemLength(uint32_t index,
                          const std::vector<FX_FILESIZE>& szArray);
 
@@ -56,7 +53,7 @@ class CPDF_HintTables {
   CPDF_DataAvail* const m_pDataAvail;
 
   // Owned by |m_pDataAvail|.
-  CPDF_Dictionary* const m_pLinearizedDict;
+  CPDF_Linearized* const m_pLinearized;
 
   uint32_t m_nFirstPageSharedObjs;
   FX_FILESIZE m_szFirstPageObjOffset;
diff --git a/core/fpdfapi/parser/cpdf_linearized.cpp b/core/fpdfapi/parser/cpdf_linearized.cpp
new file mode 100644
index 0000000000..ec57f100cb
--- /dev/null
+++ b/core/fpdfapi/parser/cpdf_linearized.cpp
@@ -0,0 +1,71 @@
+// 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.h"
+
+#include "core/fpdfapi/parser/cpdf_array.h"
+#include "core/fpdfapi/parser/cpdf_dictionary.h"
+#include "core/fpdfapi/parser/cpdf_number.h"
+#include "third_party/base/ptr_util.h"
+
+namespace {
+
+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;
+}
+
+}  // namespace
+
+// static
+std::unique_ptr<CPDF_Linearized> CPDF_Linearized::CreateForObject(
+    std::unique_ptr<CPDF_Object> pObj) {
+  auto pDict = ToDictionary(std::move(pObj));
+  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", 0) ||
+      !IsValidNumericDictionaryValue<FX_FILESIZE>(pDict.get(), "E", 1) ||
+      !IsValidNumericDictionaryValue<uint32_t>(pDict.get(), "O", 1))
+    return nullptr;
+  return pdfium::WrapUnique(new CPDF_Linearized(pDict.get()));
+}
+
+CPDF_Linearized::CPDF_Linearized(const CPDF_Dictionary* pDict) {
+  if (!pDict)
+    return;
+  m_szFileSize = pDict->GetIntegerFor("L");
+  m_dwFirstPageNo = pDict->GetIntegerFor("P");
+  m_szLastXRefOffset = pDict->GetIntegerFor("T");
+  m_PageCount = pDict->GetIntegerFor("N");
+  m_szFirstPageEndOffset = pDict->GetIntegerFor("E");
+  m_FirstPageObjNum = pDict->GetIntegerFor("O");
+  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);
+    m_szHintLength = std::max(pHintStreamRange->GetIntegerAt(1), 0);
+  }
+}
+
+CPDF_Linearized::~CPDF_Linearized() {}
+
+bool CPDF_Linearized::HasHintTable() const {
+  return GetPageCount() > 1 && GetHintStart() > 0 && GetHintLength() > 0;
+}
diff --git a/core/fpdfapi/parser/cpdf_linearized.h b/core/fpdfapi/parser/cpdf_linearized.h
new file mode 100644
index 0000000000..caf538e3fe
--- /dev/null
+++ b/core/fpdfapi/parser/cpdf_linearized.h
@@ -0,0 +1,55 @@
+// 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
+
+#ifndef CORE_FPDFAPI_PARSER_CPDF_LINEARIZED_H_
+#define CORE_FPDFAPI_PARSER_CPDF_LINEARIZED_H_
+
+#include <memory>
+
+#include "core/fxcrt/fx_memory.h"
+#include "core/fxcrt/fx_stream.h"
+
+class CPDF_Dictionary;
+class CPDF_Object;
+
+class CPDF_Linearized {
+ public:
+  ~CPDF_Linearized();
+  static std::unique_ptr<CPDF_Linearized> CreateForObject(
+      std::unique_ptr<CPDF_Object> pObj);
+
+  // Will only return values > 0.
+  FX_FILESIZE GetFileSize() const { return m_szFileSize; }
+  uint32_t GetFirstPageNo() const { return m_dwFirstPageNo; }
+  // Will only return values > 0.
+  FX_FILESIZE GetLastXRefOffset() const { return m_szLastXRefOffset; }
+  uint32_t GetPageCount() const { return m_PageCount; }
+  // Will only return values > 0.
+  FX_FILESIZE GetFirstPageEndOffset() const { return m_szFirstPageEndOffset; }
+  // Will only return values > 0.
+  uint32_t GetFirstPageObjNum() const { return m_FirstPageObjNum; }
+
+  bool HasHintTable() const;
+  // Will only return values > 0.
+  FX_FILESIZE GetHintStart() const { return m_szHintStart; }
+  // Will only return values > 0.
+  FX_FILESIZE GetHintLength() const { return m_szHintLength; }
+
+ protected:
+  explicit CPDF_Linearized(const CPDF_Dictionary* pDict);
+
+ private:
+  FX_FILESIZE m_szFileSize = 0;
+  uint32_t m_dwFirstPageNo = 0;
+  FX_FILESIZE m_szLastXRefOffset = 0;
+  uint32_t m_PageCount = 0;
+  FX_FILESIZE m_szFirstPageEndOffset = 0;
+  uint32_t m_FirstPageObjNum = 0;
+  FX_FILESIZE m_szHintStart = 0;
+  FX_FILESIZE m_szHintLength = 0;
+};
+
+#endif  // CORE_FPDFAPI_PARSER_CPDF_LINEARIZED_H_
diff --git a/core/fpdfapi/parser/cpdf_parser.cpp b/core/fpdfapi/parser/cpdf_parser.cpp
index c8c07bd0b7..044d12d6ef 100644
--- a/core/fpdfapi/parser/cpdf_parser.cpp
+++ b/core/fpdfapi/parser/cpdf_parser.cpp
@@ -12,6 +12,7 @@
 #include "core/fpdfapi/parser/cpdf_crypto_handler.h"
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fpdfapi/parser/cpdf_document.h"
+#include "core/fpdfapi/parser/cpdf_linearized.h"
 #include "core/fpdfapi/parser/cpdf_number.h"
 #include "core/fpdfapi/parser/cpdf_reference.h"
 #include "core/fpdfapi/parser/cpdf_security_handler.h"
@@ -54,8 +55,6 @@ CPDF_Parser::CPDF_Parser()
       m_pTrailer(nullptr),
       m_pEncryptDict(nullptr),
       m_bVersionUpdated(false),
-      m_pLinearized(nullptr),
-      m_dwFirstPageNo(0),
       m_dwXrefStartObjNum(0) {
   m_pSyntax.reset(new CPDF_SyntaxParser);
 }
@@ -72,8 +71,6 @@ CPDF_Parser::~CPDF_Parser() {
 
   for (CPDF_Dictionary* trailer : m_Trailers)
     delete trailer;
-
-  delete m_pLinearized;
 }
 
 uint32_t CPDF_Parser::GetLastObjNum() const {
@@ -1402,6 +1399,10 @@ CPDF_Object* CPDF_Parser::ParseIndirectObjectAtByStrict(
   return pObj;
 }
 
+uint32_t CPDF_Parser::GetFirstPageNo() const {
+  return m_pLinearized ? m_pLinearized->GetFirstPageNo() : 0;
+}
+
 CPDF_Dictionary* CPDF_Parser::LoadTrailerV4() {
   if (m_pSyntax->GetKeyword() != "trailer")
     return nullptr;
@@ -1448,35 +1449,14 @@ bool CPDF_Parser::IsLinearizedFile(IFX_SeekableReadStream* pFileAccess,
     return false;
   }
 
-  m_pLinearized = m_pSyntax->GetObject(nullptr, objnum, gennum, true);
+  m_pLinearized = CPDF_Linearized::CreateForObject(
+      pdfium::WrapUnique(m_pSyntax->GetObject(nullptr, objnum, gennum, true)));
   if (!m_pLinearized)
     return false;
-
-  CPDF_Dictionary* pDict = m_pLinearized->GetDict();
-  if (pDict && pDict->GetObjectFor("Linearized")) {
-    m_pSyntax->GetNextWord(nullptr);
-
-    CPDF_Object* pLen = pDict->GetObjectFor("L");
-    if (!pLen) {
-      delete m_pLinearized;
-      m_pLinearized = nullptr;
-      return false;
-    }
-
-    if (pLen->GetInteger() != (int)pFileAccess->GetSize())
-      return false;
-
-    if (CPDF_Number* pNo = ToNumber(pDict->GetObjectFor("P")))
-      m_dwFirstPageNo = pNo->GetInteger();
-
-    if (CPDF_Number* pTable = ToNumber(pDict->GetObjectFor("T")))
-      m_LastXRefOffset = pTable->GetInteger();
-
-    return true;
-  }
-  delete m_pLinearized;
-  m_pLinearized = nullptr;
-  return false;
+  m_LastXRefOffset = m_pLinearized->GetLastXRefOffset();
+  // Move parser onto first page xref table start.
+  m_pSyntax->GetNextWord(nullptr);
+  return true;
 }
 
 CPDF_Parser::Error CPDF_Parser::StartLinearizedParse(
@@ -1525,7 +1505,7 @@ CPDF_Parser::Error CPDF_Parser::StartLinearizedParse(
   if (eRet != SUCCESS)
     return eRet;
 
-  m_pDocument->LoadLinearizedDoc(m_pLinearized->GetDict());
+  m_pDocument->LoadLinearizedDoc(m_pLinearized.get());
   if (!m_pDocument->GetRoot() || m_pDocument->GetPageCount() == 0) {
     if (bXRefRebuilt)
       return FORMAT_ERROR;
@@ -1538,7 +1518,7 @@ CPDF_Parser::Error CPDF_Parser::StartLinearizedParse(
     if (eRet != SUCCESS)
       return eRet;
 
-    m_pDocument->LoadLinearizedDoc(m_pLinearized->GetDict());
+    m_pDocument->LoadLinearizedDoc(m_pLinearized.get());
     if (!m_pDocument->GetRoot())
       return FORMAT_ERROR;
   }
diff --git a/core/fpdfapi/parser/cpdf_parser.h b/core/fpdfapi/parser/cpdf_parser.h
index 3be157a1a2..b8ce7ab294 100644
--- a/core/fpdfapi/parser/cpdf_parser.h
+++ b/core/fpdfapi/parser/cpdf_parser.h
@@ -19,6 +19,7 @@ class CPDF_CryptoHandler;
 class CPDF_Dictionary;
 class CPDF_Document;
 class CPDF_IndirectObjectHolder;
+class CPDF_Linearized;
 class CPDF_Object;
 class CPDF_SecurityHandler;
 class CPDF_StreamAcc;
@@ -88,7 +89,7 @@ class CPDF_Parser {
       uint32_t objnum,
       FX_FILESIZE* pResultPos);
 
-  uint32_t GetFirstPageNo() const { return m_dwFirstPageNo; }
+  uint32_t GetFirstPageNo() const;
 
  protected:
   struct ObjectInfo {
@@ -157,8 +158,7 @@ class CPDF_Parser {
   std::set<FX_FILESIZE> m_SortedOffset;
   std::vector<CPDF_Dictionary*> m_Trailers;
   bool m_bVersionUpdated;
-  CPDF_Object* m_pLinearized;
-  uint32_t m_dwFirstPageNo;
+  std::unique_ptr<CPDF_Linearized> m_pLinearized;
   uint32_t m_dwXrefStartObjNum;
 
   // A map of object numbers to indirect streams. Map owns the streams.