rand_range_int() computed `end - begin + 1` in mrb_int before checking
for a reversed or empty range. For extreme bounds the subtraction itself
overflowed mrb_int (UndefinedBehaviorSanitizer signed-integer-overflow),
and the wraparound could turn a reversed range into a positive span,
defeating the guard.
Reject reversed or empty ranges before subtracting, and compute the
candidate count in unsigned arithmetic, so no signed overflow is
possible. A new unsigned uniform sampler draws from the full mrb_int
domain, so valid ranges whose width exceeds MRB_INT_MAX now return a
uniform in-range value instead of nil, matching CRuby.
Co-authored-by: Claude <noreply@anthropic.com>
For Array#sample and Array#shuffle. They used to take optional ordinal
argument for Random object but CRuby uses `random:` keyword argument.
Now mruby is compatible with CRuby here.
* The `Fixnum` constant is now an alias for the `Integer` class.
* Remove `struct mrb_state::fixnum_class` member.
If necessary, use `struct mrb_state::integer_class` instead.
The ISO standard does not include implicit type conversion using
`to_int`. This implicit conversion often causes vulnerability.
There will be no more attacks like #4120.
In addition, we have added internal convenience method `__to_int` which
does type check and conversion (from floats).
Yukihiro "Matz" Matsumoto