RE: [PATCH 1/1] fport_print: handle ttyname ENODEV

Maxime Devos <[email protected]> writes:

> I don’t think the ‘#define FUNC_NAME "scm_i_c_ttyname"’ is actually
> doing something for scm_i_ttyname, given the absence of SCM_SYSERROR.

Ahh, thanks.  With the rework, I don't need that anymore.

> Since the internal function is only used in the same file as which it
> is defined in, you can make it a static function and remove it from
> posix.h.

It's also used in fports.c in the patch -- we need the helper so we can
get the errno in order to handle ENODEV in fport_print.

> And shouldn’t be the description of the function be right before the
> function declaration (and maybe before the #if too, dunno) instead of
> inside?

In this case, I was just including it as an indication of the helper's
intent rather than "real" documentation.

> Also, the locking is like...

OK, so you're saying that the existing scm_ttyname() is potentially
broken in these ways.  Assuming so, then I might see about handling that
right now, but I think it could also be filed as a bug for later.

And depending on what you mean by "non-standard", I don't know whether
that change (e.g. to allow EINTR to propagate, and to stop processing
ticks) could go into a stable release.

In any case, I'm happy to fix all the problems if we can be confident
we're not causing a regression, and not introducing something
inappropriate for a Z release -- I'll probably look into it a bit
further today, but for now, my more immediate goal is to fix the test by
fixing the ENODEV problem, without making anything worse.

> On length checks and the like: it isn’t clear to me whether
> TTY_NAME_MAX includes the terminating zero or not (I would expect not,
> like strlen).

I wsn't sure at first either, but then I saw that POSIX says "The value
of namesize is smaller than the length of the string to be returned
including the terminating null character" for the ERANGE case, so I
assumed it was included:
https://pubs.opengroup.org/onlinepubs/9699919799/functions/ttyname.html

Thanks
-- 
Rob Browning
rlb @defaultvalue.org and @debian.org
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