I think overflow occurs when w * h > SIZE_MAX So you just want to make sure that w > 0 and w * h <= SIZE_MAX. But if w * h is large enough, it overflows, w

I think overflow occurs when w * h > SIZE_MAX So you just want to make sure that w > 0 and w * h <= SIZE_MAX. But if w * h is large enough, it overflows, which would result in w * h <= SIZE_MAX being evaluated to true. I agree that it is confusing though.