Lock page in LoadFXAnnot to prevent unintended page closing

fpdfsdk/src/fpdfview.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/fsdk_define.h"
+#include "../include/fsdk_mgr.h"
 #include "../include/fpdfview.h"
 #include "../include/fsdk_rendercontext.h"
 #include "../include/fpdf_progressive.h"
 #include "../include/fpdf_ext.h"
 #include "../../third_party/numerics/safe_conversions_impl.h"
 
 CPDF_CustomAccess::CPDF_CustomAccess(FPDF_FILEACCESS* pFileAccess)
 {
         if (pFileAccess)
                 m_FileAccess = *pFileAccess;
@@ skipping 566 matching lines @@
 
         Func_RenderPage(pContext, page, start_x, start_y, size_x, size_y, rotate, flags,TRUE,NULL);
 
         delete pContext;
         pPage->RemovePrivateData((void*)1);
 }
 
 DLLEXPORT void STDCALL FPDF_ClosePage(FPDF_PAGE page)
 {
         if (!page) return;
+        CPDFSDK_PageView* pPageView = (CPDFSDK_PageView*)(((CPDF_Page*)page))->GetPrivateData((FX_LPVOID)page);
+        if (pPageView && pPageView->IsLocked()) {
+            pPageView->TakeOverPage();
+            return;
+        }
         delete (CPDF_Page*)page;
 
 }
 
 DLLEXPORT void STDCALL FPDF_CloseDocument(FPDF_DOCUMENT document)
 {
         if (!document)
                 return;
         CPDF_Document* pDoc = (CPDF_Document*)document; 
         CPDF_Parser* pParser = (CPDF_Parser*)pDoc->GetParser();
@@ skipping 245 matching lines @@
 {
         if (document == NULL)
                 return NULL;
         if (name == NULL || name[0] == 0) 
                 return NULL;
 
         CPDF_Document* pDoc = (CPDF_Document*)document;
         CPDF_NameTree name_tree(pDoc, FX_BSTRC("Dests"));
         return name_tree.LookupNamedDest(pDoc, name);
 }