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

xfa/fgas/font/fgas_stdfontmgr.cpp

 // Copyright 2015 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
 
 #include "xfa/fgas/font/fgas_stdfontmgr.h"
 
 #include "core/fxcrt/fx_stream.h"
 #include "core/fxge/cfx_fontmapper.h"
@@ skipping 851 matching lines @@
 
 unsigned long _ftStreamRead(FXFT_Stream stream,
                             unsigned long offset,
                             unsigned char* buffer,
                             unsigned long count) {
   if (count == 0)
     return 0;
 
   IFX_SeekableReadStream* pFile =
       (IFX_SeekableReadStream*)stream->descriptor.pointer;
-  int res = pFile->ReadBlock(buffer, offset, count);
-  if (res)
-    return count;
+  unsigned long readSize =
+      static_cast<unsigned long>(pFile->ReadBlock(buffer, offset, count));
+  if (readSize == count || pFile->IsEOF())
+    return readSize;
   return 0;
 }
 
 void _ftStreamClose(FXFT_Stream stream) {}
 
 };  // extern "C"
 
 FXFT_Face CFGAS_FontMgrImp::LoadFace(IFX_SeekableReadStream* pFontStream,
                                      int32_t iFaceIndex) {
   if (!pFontStream)
@@ skipping 490 matching lines @@
 
 int32_t CFGAS_FontMgrImp::IsPartName(const CFX_WideString& Name1,
                                      const CFX_WideString& Name2) {
   if (Name1.Find(Name2.c_str()) != -1) {
     return 1;
   }
   return 0;
 }
 
 #endif