Currently, GetUnsigned() calls strtoul and checks whether the resulting
unsigned long int is greater than UINT_MAX. This implicitly assumes that
UINT_MAX < ULONG_MAX.
Problematically, `unsigned long int` and `unsigned` have the same size
on Windows [0] and on 32-bit architectures.
For correctness, we now check whether strtoul failed because it would
overflow the unsigned long int before checking whether the value fits in
an unsigned type.
[0]: https://docs.microsoft.com/en-us/cpp/cpp/data-type-ranges?view=msvc-160
Change-Id: I49702febf4543bfb7991592717443e0b2adb954f
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48545
Commit-Queue: Dan McArdle <dmcardle@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Dan McArdle
Adam Langley