in the attempt to fix 627393, changed IFX_FileRead's readBlock to return the length it reads

xfa/fxfa/xfa_ffapp.h

 // 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
 
 #ifndef XFA_FXFA_XFA_FFAPP_H_
 #define XFA_FXFA_XFA_FFAPP_H_
 
 #include <memory>
@@ skipping 11 matching lines @@
 class CXFA_FWLTheme;
 class CXFA_FFDocHandler;
 class CXFA_FontMgr;
 class IFWL_AdapterTimerMgr;
 
 class CXFA_FileRead : public IFX_SeekableReadStream {
  public:
   explicit CXFA_FileRead(const std::vector<CPDF_Stream*>& streams);
   ~CXFA_FileRead() override;
 
-  // IFX_SeekableReadStream
+  // IFX_FileRead
+  bool IsEOF() override;
   FX_FILESIZE GetSize() override;
-  bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
+  size_t ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
   void Release() override;
 
  protected:
   CFX_ObjectArray<CPDF_StreamAcc> m_Data;
+  FX_FILESIZE m_FileSize;
+  FX_FILESIZE m_nCurPos;
 };
 
 class CXFA_FFApp {
  public:
   explicit CXFA_FFApp(IXFA_AppProvider* pProvider);
   ~CXFA_FFApp();
 
   CXFA_FFDoc* CreateDoc(IXFA_DocEnvironment* pDocEnvironment,
                         IFX_SeekableReadStream* pStream,
                         bool bTakeOverFile);
@@ skipping 39 matching lines @@
   std::unique_ptr<CXFA_FWLAdapterWidgetMgr> m_pAdapterWidgetMgr;
   CFWL_WidgetMgrDelegate* m_pWidgetMgrDelegate;  // not owned.
 
   // |m_pFWLApp| has to be released first, then |m_pFWLTheme| since the former
   // may refers to theme manager and the latter refers to font manager.
   std::unique_ptr<CXFA_FWLTheme> m_pFWLTheme;
   std::unique_ptr<IFWL_App> m_pFWLApp;
 };
 
 #endif  // XFA_FXFA_XFA_FFAPP_H_