When normalize coordinate, return instead of assert() when divide by 0

core/include/fxcrt/fx_coordinates.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 _FXCRT_COORDINATES_
 #define _FXCRT_COORDINATES_
 template<class baseType> class CFX_PSVTemplate;
 template<class baseType> class CFX_VTemplate;
@@ skipping 138 matching lines @@
     {
         return FXT_PSV::x * FXT_PSV::x + FXT_PSV::y * FXT_PSV::y;
     }
     baseType    Length() const
     {
         return FXSYS_sqrt(FXT_PSV::x * FXT_PSV::x + FXT_PSV::y * FXT_PSV::y);
     }
     void                Normalize()
     {
         FX_FLOAT fLen = FXSYS_sqrt(FXT_PSV::x * FXT_PSV::x + FXT_PSV::y * FXT_PSV::y);
-        FXSYS_assert(fLen >= 0.0001f);
+        if (fLen < 0.0001f) {

[Tom Sepez, 2014/08/04 17:09:38]

Isn't .0001f a kinda large value for near-zero? I'd expect you could get a few
more sig digits here.

Do we want to set both x and y to something (like 0.0) when the length is 0?

[Bo Xu, 2014/08/04 18:48:09]

For some fuzz test, the x, and y are set to be really large values like over
1e20. After some matrix transformation, the fLen is computed to -1.#IND0004 or
-1.#INF0004. In these situations, I think we should leave these values there for
later application processing but not change to zero.

I can check with the devs on the 0.0001f, but this number is for the objects
spacing in PDF and 0.00001f is a reasonable "0" for a spacing in the PDF world.

+            return;
+        }
         FXT_PSV::x = ((baseType)FXT_PSV::x) / fLen;
         FXT_PSV::y = ((baseType)FXT_PSV::y) / fLen;
     }
     baseType    DotProduct(baseType x, baseType y) const
     {
         return FXT_PSV::x * x + FXT_PSV::y * y;
     }
     baseType    DotProduct(const FXT_VECTOR &v) const
     {
         return FXT_PSV::x * v.x + FXT_PSV::y * v.y;
@@ skipping 721 matching lines @@
 public:
     FX_FLOAT a;
     FX_FLOAT b;
     FX_FLOAT c;
     FX_FLOAT d;
     FX_FLOAT e;
     FX_FLOAT f;
 };
 #define CFX_AffineMatrix        CFX_Matrix
 #endif