HexStringToUInt64 should fail for negative input

base/strings/string_number_conversions.cc

Index: base/strings/string_number_conversions.cc
diff --git a/base/strings/string_number_conversions.cc b/base/strings/string_number_conversions.cc
index fadc81a186f6631a5e5226e49a1e11b969ec2f70..1ef6e631d7c9541181986700dfbe38a34f3407c9 100644
--- a/base/strings/string_number_conversions.cc
+++ b/base/strings/string_number_conversions.cc
@@ -500,6 +500,9 @@ bool HexStringToInt64(const StringPiece& input, int64* output) {
 }
 
 bool HexStringToUInt64(const StringPiece& input, uint64* output) {
+  if (input[0] == '-') {
+    return false;

[brettw, 2013/04/24 05:42:05]

The header file defines that the best effort result should saturate (so should
return 0 in the negative cases). Is there something broken in the template code?
It seems like there's a bunch of stuff to test for negative numbers, but I don't
see any unit tests for StringToUint so am suspicious.

[Mostyn Bramley-Moore, 2013/04/24 08:19:20]

The template code only seems to check for valid negative numbers (eg I think it
would spot "-12-12" as invalid), but does not check that the value type is
signed.

I moved the negativity/signed check inside the template code, I guess it's a
more complete fix (in case other unsigned types are added later).

+  }
   return IteratorRangeToNumber<HexIteratorRangeToUInt64Traits>::Invoke(
       input.begin(), input.end(), output);
 }