[Toybox] [PATCH] xgetrandom: fix macOS build.

[Rob Landley]

On 6/19/22 12:37, enh via Toybox wrote:
> BSD has <sys/random.h> first, but has getentropy() in there. glibc
> has getentropy() in addition to getrandom(), but they keep it in
> <unistd.h> instead. Since both went in in glibc 2.25 I don't think
> this will matter in practice, but if this does cause trouble, we
> can have separate getentropy() and getrandom() implementations for
> the BSDs versus glibc.

Hmmm... git annotate says
https://github.com/bminor/glibc/commit/ccb8b7f7d48 from december 27,
2016. No wait, that was inside an #ifdef STALLMAN_FTAGHN which changed
to something realistic in commit
https://github.com/bminor/glibc/commit/a851999f61a four days later.

Five and a half years, meaning maybe five in distros. Not the full
seven, but I'll wait for somebody to complain I guess?

> This does mean that the only valid values for `flags` are now 0 or
> WARN_ONLY, but that was already effectively true anyway because
> GRND_NONBLOCK != O_NONBLOCK so the fallback path was already broken.

Everything should always be reading from /dev/urandom not /dev/random
these days. Anything else is a denial of service attack waiting to
happen. (Either the pool is properly initialized or it isn't.)

Rob