Fix for #618267. Adding a method to determine if multiplication has

core/fxcodec/codec/fx_codec_tiff.cpp

Index: core/fxcodec/codec/fx_codec_tiff.cpp
diff --git a/core/fxcodec/codec/fx_codec_tiff.cpp b/core/fxcodec/codec/fx_codec_tiff.cpp
index 09cfea41116576fb2113b23866af5d50d61877b1..204e6cb41f26a2c797711da27e53248f57aa1072 100644
--- a/core/fxcodec/codec/fx_codec_tiff.cpp
+++ b/core/fxcodec/codec/fx_codec_tiff.cpp
@@ -79,6 +79,10 @@ int _TIFFmemcmp(const void* ptr1, const void* ptr2, tmsize_t size) {
   return FXSYS_memcmp(ptr1, ptr2, (size_t)size);
 }
 
+int _TIFFIfMultiplicationOverflow(tmsize_t op1, tmsize_t op2) {

[Tom Sepez, 2016/08/26 23:05:28]

Should be bool return value.  Also, we return true when it doesn't overflow
(right?), which is opposite of what the name suggests to me.  Maybe
_TIFFMultiplicationSafeFromOverflow() or some such?

[tracy_jiang, 2016/08/26 23:44:16]

We will change the naming logic. It made sense to us.
The reason we used int was that this method is declared in
third_party/libtiff/tiffio.h. tiffio.h holds a bunch of 
C function signatures and will not allow 'bool' to be compiled
We declared it in tiffio.h was because other tiff auxiliary
methods are declared in the same place like _TIFFmemcpy etc.
Also in libtiff there is not a thing similar to FX_BOOL in
non-third-party places.
So do you think we should use int here or should we typedef a 
TIFF_BOOL?

+  return op1 <= std::numeric_limits<tmsize_t>::max() / op2;
+}
+
 TIFFErrorHandler _TIFFwarningHandler = nullptr;
 TIFFErrorHandler _TIFFerrorHandler = nullptr;