We have bool now

B missing

Sorry, I'm a bit too tired to double check against style(9), but these seem to be in wrong order.

Why the ugly underscores?

Is this Gray encoding, after Frank Gray?

I may be wrong, but I think we want to avoid using atoi() in new code.

Aren't we dropping this from wherever we can legally?

is this daemon(3)? That returns an int, which would mandate an explicit comparison.

Indeed atoi(3) says

The atoi() function has been deprecated by strtol() and should not be
used in new code.

Yeah the standard copyright template for new code no longer has this. It's not a big deal but serves no purpose so if there's no other reason to include it (e.g. your employer requires it) then I'd leave it out.

Yes, I'll fix the spelling.

I'll fix it.

Fixed.

All includes are now sorted by name.

Fixed.

"Kernel includes come first"

Subjective note, but this looks awkward to me, especially with the quotes. I would just call it as everyone else: "apply Gray code".

clang-format says:

include <sys/soundcard.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <math.h>
#include <paths.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

I don't have the authority to say for sure, but I think we should use space to separate the numbers from the units here and below.