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

core/fxcrt/include/fx_stream.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 CORE_FXCRT_INCLUDE_FX_STREAM_H_
 #define CORE_FXCRT_INCLUDE_FX_STREAM_H_
 
 #include "core/fxcrt/include/fx_string.h"
@@ skipping 65 matching lines @@
   virtual void Release() = 0;
   virtual FX_BOOL IsEOF() = 0;
   virtual FX_FILESIZE GetPosition() = 0;
   virtual size_t ReadBlock(void* buffer, size_t size) = 0;
 };
 
 class IFX_FileRead : public IFX_StreamRead {
  public:
   // IFX_StreamRead:
   void Release() override = 0;
-  FX_BOOL IsEOF() override;
+  FX_BOOL IsEOF() override = 0;
   FX_FILESIZE GetPosition() override;
   size_t ReadBlock(void* buffer, size_t size) override;
 
-  virtual FX_BOOL ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) = 0;
+  virtual size_t ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) = 0;
   virtual FX_FILESIZE GetSize() = 0;
 };
 
 IFX_FileRead* FX_CreateFileRead(const FX_CHAR* filename);
 IFX_FileRead* FX_CreateFileRead(const FX_WCHAR* filename);
 
 class IFX_FileStream : public IFX_FileRead, public IFX_FileWrite {
  public:
   virtual IFX_FileStream* Retain() = 0;
 
   // IFX_FileRead:
   void Release() override = 0;
   FX_BOOL IsEOF() override = 0;
   FX_FILESIZE GetPosition() override = 0;
   size_t ReadBlock(void* buffer, size_t size) override = 0;
-  FX_BOOL ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override = 0;
+  size_t ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override = 0;
   FX_FILESIZE GetSize() override = 0;
 
   // IFX_FileWrite:
   FX_BOOL WriteBlock(const void* buffer,
                      FX_FILESIZE offset,
                      size_t size) override = 0;
   FX_BOOL WriteBlock(const void* buffer, size_t size) override;
   FX_BOOL Flush() override = 0;
 };
 
@@ skipping 36 matching lines @@
   FX_FILESIZE GetPosition() override = 0;
   size_t ReadBlock(void* buffer, size_t size) override = 0;
 
   virtual FX_BOOL ReadNextBlock(FX_BOOL bRestart = FALSE) = 0;
   virtual const uint8_t* GetBlockBuffer() = 0;
   virtual size_t GetBlockSize() = 0;
   virtual FX_FILESIZE GetBlockOffset() = 0;
 };
 
 #endif  // CORE_FXCRT_INCLUDE_FX_STREAM_H_