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

xfa/fxfa/include/xfa_ffapp.h

Index: xfa/fxfa/include/xfa_ffapp.h
diff --git a/xfa/fxfa/include/xfa_ffapp.h b/xfa/fxfa/include/xfa_ffapp.h
index 8a60ce6195dc187d4fa671f679a3eea46a5d88e2..59096696d4d7bc5c94e315b2f041a30a566149c3 100644
--- a/xfa/fxfa/include/xfa_ffapp.h
+++ b/xfa/fxfa/include/xfa_ffapp.h
@@ -29,12 +29,15 @@ class CXFA_FileRead : public IFX_FileRead {
   ~CXFA_FileRead() override;
 
   // IFX_FileRead
+  FX_BOOL IsEOF() override;
   FX_FILESIZE GetSize() override;
-  FX_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 {