Correctly check for overflow in FX_atonum.

core/fxcrt/fx_basic_util.cpp

 // 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
 
 #include "core/fxcrt/include/fx_basic.h"
 #include "core/fxcrt/include/fx_ext.h"
 
 #include <cctype>
@@ skipping 76 matching lines @@
   return NULL;
 }
 void CFX_PrivateData::ClearAll() {
   FX_PRIVATEDATA* pList = m_DataList.GetData();
   int count = m_DataList.GetSize();
   for (int i = 0; i < count; i++) {
     pList[i].FreeData();
   }
   m_DataList.RemoveAll();
 }
+
 void FX_atonum(const CFX_ByteStringC& strc, FX_BOOL& bInteger, void* pData) {
   if (strc.Find('.') == -1) {
     bInteger = TRUE;
     int cc = 0;
-    int integer = 0;
+    pdfium::base::CheckedNumeric<int> integer = 0;
     FX_STRSIZE len = strc.GetLength();
     bool bNegative = false;
     if (strc[0] == '+') {
       cc++;
     } else if (strc[0] == '-') {
       bNegative = true;
       cc++;
     }
     while (cc < len && std::isdigit(strc[cc])) {
-      // TODO(dsinclair): This is not the right way to handle overflow.
       integer = integer * 10 + FXSYS_toDecimalDigit(strc.CharAt(cc));
-      if (integer < 0)
+      if (!integer.IsValid())
         break;
       cc++;
     }
     if (bNegative) {
       integer = -integer;
     }
-    *(int*)pData = integer;
+    *(int*)pData = integer.ValueOrDefault(0);
   } else {
     bInteger = FALSE;
     *(FX_FLOAT*)pData = FX_atof(strc);
   }
 }
+
 FX_FLOAT FX_atof(const CFX_ByteStringC& strc) {
   if (strc.IsEmpty())
     return 0.0;
 
   int cc = 0;
   bool bNegative = false;
   int len = strc.GetLength();
   if (strc[0] == '+') {
     cc++;
   } else if (strc[0] == '-') {
@@ skipping 220 matching lines @@
       d * m.b + e * m.e + f * m.h, d * m.c + e * m.f + f * m.i,
       g * m.a + h * m.d + i * m.g, g * m.b + h * m.e + i * m.h,
       g * m.c + h * m.f + i * m.i);
 }
 
 CFX_Vector_3by1 CFX_Matrix_3by3::TransformVector(const CFX_Vector_3by1& v) {
   return CFX_Vector_3by1(a * v.a + b * v.b + c * v.c,
                          d * v.a + e * v.b + f * v.c,
                          g * v.a + h * v.b + i * v.c);
 }