CPDF_Parser shouldnt be in the business of opening files

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 "../../core/include/fxcodec/fx_codec.h"
 #include "../../core/include/fxcrt/fx_safe_types.h"
 #include "../../public/fpdf_ext.h"
 #include "../../public/fpdf_progressive.h"
@@ skipping 137 matching lines @@
       break;
   }
   SetLastError(err_code);
 }
 
 DLLEXPORT void STDCALL FPDF_SetSandBoxPolicy(FPDF_DWORD policy,
                                              FPDF_BOOL enable) {
   return FSDK_SetSandBoxPolicy(policy, enable);
 }
 
+
 DLLEXPORT FPDF_DOCUMENT STDCALL FPDF_LoadDocument(FPDF_STRING file_path,
                                                   FPDF_BYTESTRING password) {
+  // NOTE: the creation of the file needs to be by the embedder on the
+  // other side of this API.
+  IFX_FileRead* pFileAccess = FX_CreateFileRead((const FX_CHAR*)file_path);
+  if (!pFileAccess) {
+    return nullptr;
+  }
+
   CPDF_Parser* pParser = new CPDF_Parser;
   pParser->SetPassword(password);
 
-  FX_DWORD err_code = pParser->StartParse((const FX_CHAR*)file_path);
+  FX_DWORD err_code = pParser->StartParse(pFileAccess);
   if (err_code) {
     delete pParser;
     ProcessParseError(err_code);
     return NULL;
   }
   return pParser->GetDocument();
 }
 
 extern void CheckUnSupportError(CPDF_Document* pDoc, FX_DWORD err_code);
 
@@ skipping 726 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;
 }