Fix -INT_MIN integer overflow in string_number_conversions.cc.

base/strings/string_number_conversions.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/strings/string_number_conversions.h"
 
 #include <ctype.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <wctype.h>
@@ skipping 24 matching lines @@
   template <typename INT2, typename UINT2>
   struct ToUnsignedT<INT2, UINT2, false> {
     static UINT2 ToUnsigned(INT2 value) {
       return static_cast<UINT2>(value);
     }
   };
 
   template <typename INT2, typename UINT2>
   struct ToUnsignedT<INT2, UINT2, true> {
     static UINT2 ToUnsigned(INT2 value) {
-      return static_cast<UINT2>(value < 0 ? -value : value);
+      if (value >= 0) {
+        return value;
+      } else {
+        // Avoid integer overflow when negating INT_MIN.
+        return static_cast<UINT2>(-(value + 1)) + 1;
+      }
     }
   };
 
   // This set of templates is very similar to the above templates, but
   // for testing whether an integer is negative.
   template <typename INT2, bool NEG2>
   struct TestNegT {};
   template <typename INT2>
   struct TestNegT<INT2, false> {
     static bool TestNeg(INT2 value) {
@@ skipping 464 matching lines @@
 bool HexStringToUInt64(const StringPiece& input, uint64* output) {
   return IteratorRangeToNumber<HexIteratorRangeToUInt64Traits>::Invoke(
       input.begin(), input.end(), output);
 }
 
 bool HexStringToBytes(const std::string& input, std::vector<uint8>* output) {
   return HexStringToBytesT(input, output);
 }
 
 }  // namespace base