Prevent undefined behaviour modifying bionic power #36686
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As it turns out, the check to prevent integer overflow when modifying bionic power is undefined behaviour. Whoops! Let's avoid that.
ZhilkinSerg
added
[C++]
This was referenced Jan 5, 2020
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Summary
SUMMARY: None
Purpose of change
#34684 (comment)
I needed a way to instantly modify bionic power so that I could test that this fix worked.
Describe the solution
Add a
Debug Bionic Powergentrait, which when activated prompts you for a number by which to modify bionic power.Cast
npowerandpower_leveltoint64_t, then add them and compare them with max power level to prevent integer overflow inCharacter::mod_bionic_power()Describe alternatives you've considered
Leaving the UB there, like I did for the past 30 or so days.
Testing
Create a character, install enough bionic power storage to push your max power level to the max. Debug in the
Debug Bionic Powergentrait, activate it and then increase your power by2000000000using it. Repeat, and notice that power does not overflow (where it is clamped to 0), and instead your power stays at the max power level.If you did that without these changes and the changes in #34684 applied, it will overflow and be clamped to 0.