Turn a failing assert into an actual check.

core/src/fpdfapi/fpdf_parser/fpdf_parser_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 "../../../include/fpdfapi/fpdf_parser.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
 
 CPDF_Document::CPDF_Document(CPDF_Parser* pParser)
@@ skipping 118 matching lines @@
     } else {
       int nPages = pKid->GetInteger(FX_BSTRC("Count"));
       if (nPagesToGo < nPages) {
         return _FindPDFPage(pKid, iPage, nPagesToGo, level + 1);
       }
       nPagesToGo -= nPages;
     }
   }
   return NULL;
 }
+
 CPDF_Dictionary* CPDF_Document::GetPage(int iPage) {
-  if (iPage < 0 || iPage >= m_PageList.GetSize()) {
-    return NULL;
-  }
+  if (iPage < 0 || iPage >= m_PageList.GetSize())
+    return nullptr;
+
   if (m_bLinearized && (iPage == (int)m_dwFirstPageNo)) {
     CPDF_Object* pObj = GetIndirectObject(m_dwFirstPageObjNum);
     if (pObj && pObj->GetType() == PDFOBJ_DICTIONARY) {
-      return (CPDF_Dictionary*)pObj;
+      return static_cast<CPDF_Dictionary*>(pObj);
     }
   }
+
   int objnum = m_PageList.GetAt(iPage);
   if (objnum) {
     CPDF_Object* pObj = GetIndirectObject(objnum);
-    ASSERT(pObj->GetType() == PDFOBJ_DICTIONARY);
-    return (CPDF_Dictionary*)pObj;
+    if (pObj && pObj->GetType() == PDFOBJ_DICTIONARY) {
+      return static_cast<CPDF_Dictionary*>(pObj);
+    }
   }
+
   CPDF_Dictionary* pRoot = GetRoot();
-  if (pRoot == NULL) {
-    return NULL;
-  }
+  if (!pRoot)
+    return nullptr;
+
   CPDF_Dictionary* pPages = pRoot->GetDict(FX_BSTRC("Pages"));
-  if (pPages == NULL) {
-    return NULL;
-  }
+  if (!pPages)
+    return nullptr;
+
   CPDF_Dictionary* pPage = _FindPDFPage(pPages, iPage, iPage, 0);
-  if (pPage == NULL) {
-    return NULL;
-  }
+  if (!pPage)
+    return nullptr;
+
   m_PageList.SetAt(iPage, pPage->GetObjNum());
   return pPage;
 }
+
 int CPDF_Document::_FindPageIndex(CPDF_Dictionary* pNode,
                                   FX_DWORD& skip_count,
                                   FX_DWORD objnum,
                                   int& index,
                                   int level) {
   if (pNode->KeyExist(FX_BSTRC("Kids"))) {
     CPDF_Array* pKidList = pNode->GetArray(FX_BSTRC("Kids"));
     if (pKidList == NULL) {
       return -1;
     }
@@ skipping 171 matching lines @@
 void CPDF_Document::ClearPageData() {
   if (m_pDocPage) {
     CPDF_ModuleMgr::Get()->GetPageModule()->ClearDoc(this);
   }
 }
 void CPDF_Document::ClearRenderData() {
   if (m_pDocRender) {
     CPDF_ModuleMgr::Get()->GetRenderModule()->ClearDocData(m_pDocRender);
   }
 }