Correct the way to count pages and to avoid infinite loop

core/include/fpdfapi/fpdf_parser.h

 // Copyright 2014 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_INCLUDE_FPDFAPI_FPDF_PARSER_H_
 #define CORE_INCLUDE_FPDFAPI_FPDF_PARSER_H_
 
 #include <map>
@@ skipping 43 matching lines @@
   return PDF_CharType[c] == 'D';
 }
 inline bool PDFCharIsOther(uint8_t c) {
   return PDF_CharType[c] == 'R';
 }
 
 inline bool PDFCharIsLineEnding(uint8_t c) {
   return c == '\r' || c == '\n';
 }
 
+template <typename T>
+class ScopedSetInsertion {
+ public:
+  ScopedSetInsertion(std::set<T>* org_set, T elem)
+      : m_Set(org_set), m_Entry(elem) {
+    m_Set->insert(m_Entry);
+  }
+  ~ScopedSetInsertion() { m_Set->erase(m_Entry); }
+
+ private:
+  std::set<T>* const m_Set;
+  const T m_Entry;
+};
+
 // Indexed by 8-bit char code, contains unicode code points.
 extern const FX_WORD PDFDocEncoding[256];
 
 class CPDF_Document : public CFX_PrivateData, public CPDF_IndirectObjectHolder {
  public:
   CPDF_Document();
   explicit CPDF_Document(CPDF_Parser* pParser);
 
   ~CPDF_Document();
 
@@ skipping 87 matching lines @@
   CFX_ByteString m_ID2;
 
   FX_BOOL m_bLinearized;
 
   FX_DWORD m_dwFirstPageNo;
 
   FX_DWORD m_dwFirstPageObjNum;
 
   CFX_DWordArray m_PageList;
 
-  int _GetPageCount() const;
+  // Retrieve page count information by getting count value from the tree nodes
+  // or walking through the tree nodes to calculate it.
+  int RetrievePageCount() const;
   CPDF_Dictionary* _FindPDFPage(CPDF_Dictionary* pPages,
                                 int iPage,
                                 int nPagesToGo,
                                 int level);
   int _FindPageIndex(CPDF_Dictionary* pNode,
                      FX_DWORD& skip_count,
                      FX_DWORD objnum,
                      int& index,
                      int level = 0);
   FX_BOOL IsContentUsedElsewhere(FX_DWORD objnum, CPDF_Dictionary* pPageDict);
@@ skipping 799 matching lines @@
                        FX_DWORD src_size,
                        const CPDF_Dictionary* pDict,
                        uint8_t*& dest_buf,
                        FX_DWORD& dest_size,
                        CFX_ByteString& ImageEncoding,
                        CPDF_Dictionary*& pImageParms,
                        FX_DWORD estimated_size,
                        FX_BOOL bImageAcc);
 
 #endif  // CORE_INCLUDE_FPDFAPI_FPDF_PARSER_H_