On Wed, Nov 16, 2022 at 02:43:13PM -0800, Kees Cook wrote: > On Mon, Nov 14, 2022 at 05:45:58PM +0100, Jason A. Donenfeld wrote: > > - (get_random_u32_below(1024) + 1) * PAGE_SIZE; > > + get_random_u32_between(1, 1024 + 1) * PAGE_SIZE; > > I really don't like "between". Can't this be named "inclusive" (and > avoid adding 1 everywhere, which seems ugly), or at least named > something less ambiguous? > > > - n = get_random_u32_below(100) + 1; > > + n = get_random_u32_between(1, 101); > > Because I find this much less readable. "Below 100" is clear: 0-99 > inclusive, plus 1, so 1-100 inclusive. "Between 1 and 101" is not obvious > to me to mean: 1-100 inclusive. > > These seem so much nicer: > get_random_u32_inclusive(1, 1024) > get_random_u32_inclusive(1, 100) Yann pointed out something similar -- the half-closed interval being confusing -- and while I was initially dismissive, I've warmed up to doing this fully closed after sending a diff of that: https://lore.kernel.org/lkml/Y3Qt8HiXj8giOnZy@xxxxxxxxx/ So okay, let's say that I'll implement the inclusive version instead. We now have two problems to solve: 1) How/whether to make f(0, UR2_MAX) safe, - without additional 64-bit arithmetic, - minimizing the number of branches. I have a few ideas I'll code golf for a bit. 2) What to call it: - between I still like, because it mirrors "I'm thinking of a number between 1 and 10 and..." that everybody knows, - inclusive I guess works, but it's not a preposition, - bikeshed color #3? I think I can make progress with (1) alone by fiddling around with godbolt enough, like usual. I could use some more ideas for (2) though. Jason
