Check whether a pdf has XFA fields before loading XFA fields

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"
@@ skipping 290 matching lines @@
         CPDFXFA_App* pProvider = FPDFXFA_GetApp();
         CPDFXFA_Document* pDocument = FX_NEW CPDFXFA_Document(pPDFDoc, pProvider);
         return pDocument;
 }
 
 DLLEXPORT FX_BOOL STDCALL FPDF_HasXFAField(FPDF_DOCUMENT document, int& docType)
 {
         if (!document)
                 return FALSE;
 
-        CPDF_Dictionary* pRoot = ((CPDF_Document*)document)->GetRoot();
+        CPDF_Document *pdfDoc = (static_cast<CPDFXFA_Document *>(document))->GetPDFDoc();
+        if (!pdfDoc)
+                return FALSE;
+
+        CPDF_Dictionary* pRoot = pdfDoc->GetRoot();
         if (!pRoot)
                 return FALSE;
 
         CPDF_Dictionary* pAcroForm = pRoot->GetDict("AcroForm");
         if (!pAcroForm)
                 return FALSE;
 
         CPDF_Object* pXFA = pAcroForm->GetElement("XFA");
         if (!pXFA)
                 return FALSE;
 
         FX_BOOL bDynamicXFA = pRoot->GetBoolean("NeedsRendering", FALSE);
 
         if (bDynamicXFA)
                 docType = DOCTYPE_DYNIMIC_XFA;
         else
                 docType = DOCTYPE_STATIC_XFA;
 
         return TRUE;
 }
 
 DLLEXPORT  FPDF_BOOL STDCALL FPDF_LoadXFA(FPDF_DOCUMENT document)
 {
-        if (!document) 
-                return FALSE;
-
-        int iDocType = DOCTYPE_PDF;
-        FX_BOOL hasXFAField = FPDF_HasXFAField(document, iDocType);
-        if (!hasXFAField)
-                return FALSE;
-        return ((CPDFXFA_Document*)document)->LoadXFADoc();
+        return document && (static_cast<CPDFXFA_Document *>(document))->LoadXFADoc();
 }
 
 
 extern void CheckUnSupportError(CPDF_Document * pDoc, FX_DWORD err_code);
 
 class CMemFile FX_FINAL: public IFX_FileRead, public CFX_Object
 {
 public:
         CMemFile(FX_BYTE* pBuf, FX_FILESIZE size):m_pBuf(pBuf),m_size(size) {}
 
@@ skipping 735 matching lines @@
     if (!buffer) {
         buflen = len;
     } else if (buflen >= len) {
         memcpy(buffer, utf16Name.c_str(), len);
         buflen = len;
     } else {
         buflen = -1;
     }
     return (FPDF_DEST)pDestObj;
 }