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

fpdfsdk/fsdk_define.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 FPDFSDK_FSDK_DEFINE_H_
 #define FPDFSDK_FSDK_DEFINE_H_
 
 #include "core/fpdfapi/parser/cpdf_parser.h"
@@ skipping 15 matching lines @@
 class IFSDK_PAUSE_Adapter;
 
 class CPDF_CustomAccess final : public IFX_SeekableReadStream {
  public:
   explicit CPDF_CustomAccess(FPDF_FILEACCESS* pFileAccess);
   ~CPDF_CustomAccess() override {}
 
   // IFX_SeekableReadStream
   FX_FILESIZE GetSize() override;
   void Release() override;
-  bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
+  bool IsEOF() override;
+  size_t ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
 
  private:
   FPDF_FILEACCESS m_FileAccess;
+  FX_FILESIZE m_nCurPos;
 };
 
 #ifdef PDF_ENABLE_XFA
 class CFPDF_FileStream : public IFX_SeekableStream {
  public:
   explicit CFPDF_FileStream(FPDF_FILEHANDLER* pFS);
   ~CFPDF_FileStream() override {}
 
   // IFX_SeekableStream:
   IFX_SeekableStream* Retain() override;
   void Release() override;
   FX_FILESIZE GetSize() override;
   bool IsEOF() override;
   FX_FILESIZE GetPosition() override;
-  bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
+  size_t ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
   size_t ReadBlock(void* buffer, size_t size) override;
   bool WriteBlock(const void* buffer, FX_FILESIZE offset, size_t size) override;
   bool Flush() override;
 
   void SetPosition(FX_FILESIZE pos) { m_nCurPos = pos; }
 
  protected:
   FPDF_FILEHANDLER* m_pFS;
   FX_FILESIZE m_nCurPos;
 };
@@ skipping 35 matching lines @@
                             int rotate,
                             int flags,
                             bool bNeedToRestore,
                             IFSDK_PAUSE_Adapter* pause);
 
 void CheckUnSupportError(CPDF_Document* pDoc, uint32_t err_code);
 void CheckUnSupportAnnot(CPDF_Document* pDoc, const CPDF_Annot* pPDFAnnot);
 void ProcessParseError(CPDF_Parser::Error err);
 
 #endif  // FPDFSDK_FSDK_DEFINE_H_