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

core/fxcrt/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_FX_STREAM_H_
 #define CORE_FXCRT_FX_STREAM_H_
 
 #include "core/fxcrt/fx_string.h"
@@ skipping 73 matching lines @@
 };
 
 class IFX_SeekableReadStream : public IFX_ReadStream {
  public:
   // IFX_ReadStream:
   void Release() override = 0;
   bool IsEOF() override;
   FX_FILESIZE GetPosition() override;
   size_t ReadBlock(void* buffer, size_t size) override;
 
-  virtual 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_SeekableReadStream* FX_CreateFileRead(const FX_CHAR* filename);
 IFX_SeekableReadStream* FX_CreateFileRead(const FX_WCHAR* filename);
 
 class IFX_SeekableStream : public IFX_SeekableReadStream,
                            public IFX_SeekableWriteStream {
  public:
   virtual IFX_SeekableStream* Retain() = 0;
 
   // IFX_SeekableReadStream:
   void Release() override = 0;
   bool IsEOF() override = 0;
   FX_FILESIZE GetPosition() override = 0;
   size_t ReadBlock(void* buffer, size_t size) override = 0;
-  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_SeekableWriteStream:
   bool WriteBlock(const void* buffer,
                   FX_FILESIZE offset,
                   size_t size) override = 0;
   bool WriteBlock(const void* buffer, size_t size) override;
   bool Flush() override = 0;
 };
 
@@ skipping 59 matching lines @@
 };
 
 class CFindFileDataW : public CFindFileData {
  public:
   ~CFindFileDataW() override {}
   WIN32_FIND_DATAW m_FindData;
 };
 #endif
 
 #endif  // CORE_FXCRT_FX_STREAM_H_