Fix receiving page, if it have not obj num.

core/fpdfapi/parser/cpdf_document.cpp

 // 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
 
 #include "core/fpdfapi/parser/cpdf_document.h"
 
 #include <memory>
 #include <set>
@@ skipping 474 matching lines @@
   if (objnum) {
     if (CPDF_Dictionary* pDict = ToDictionary(GetOrParseIndirectObject(objnum)))
       return pDict;
     return nullptr;
   }
 
   CPDF_Dictionary* pPages = GetPagesDict();
   if (!pPages)
     return nullptr;
 
+  int nPagesToGo = iPage - m_iNextPageToTraverse + 1;
+  if (nPagesToGo <= 0) {
+    // This can happen when the page does not have an object number. On repeated
+    // calls to this function for the same page index, this condition causes
+    // TraversePDFPages() to incorrectly return nullptr.
+    // Example "testing/corpus/fx/other/jetman_std.pdf"
+    // We should restart traversing in this case.
+    // TODO(art-snake): optimize this.
+    m_pTreeTraversal.clear();
+    m_iNextPageToTraverse = 0;
+    nPagesToGo = iPage + 1;
+  }
   if (m_pTreeTraversal.empty())
     m_pTreeTraversal.push_back(std::make_pair(pPages, 0));
-  int nPagesToGo = iPage - m_iNextPageToTraverse + 1;
   CPDF_Dictionary* pPage = TraversePDFPages(iPage, &nPagesToGo, 0);
   m_iNextPageToTraverse = iPage + 1;
   return pPage;
 }
 
 void CPDF_Document::SetPageObjNum(int iPage, uint32_t objNum) {
   m_PageList.SetAt(iPage, objNum);
 }
 
 int CPDF_Document::FindPageIndex(CPDF_Dictionary* pNode,
@@ skipping 529 matching lines @@
                         pBBox, pLogFont->lfWeight / 5);
   pFontDesc->SetIntegerFor("CapHeight", capheight);
   pFontDict->SetReferenceFor("FontDescriptor", this,
                              AddIndirectObject(pFontDesc));
   hFont = SelectObject(hDC, hFont);
   DeleteObject(hFont);
   DeleteDC(hDC);
   return LoadFont(pBaseDict);
 }
 #endif  //  _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_