bug#79232: tsort doesn't support -w added by POSIX 2024.

On 14/08/2025 06:01, Collin Funk wrote:
> Collin Funk <[email protected]> writes:
> 
>> I'll have a look at implementing this behavior. But figured it was worth
>> sending on bug-coreutils for tracking like the rest of the missing POSIX
>> 2024 features.
> 
> I have attached a proposed patch.
> 
> I followed the POSIX recommendation of using the exit status 0 - 124 for
> the number of cycles and 125 for program errors (e.g. closing standard
> output).

-w seems a bit arbitrary to standardize since I only see it in OpenBSD:
https://manned.org/man/openbsd-7.7/tsort
Also exit status is a weird interface to propagate numbers,
with various limitations and overlaps.

But it doesn't cost much to implement, so fair enough.

It's good to limit to < 125 anyway.
> But I have hidden the 125 exit status behind POSIXLY_CORRECT. To avoid
> breaking something like this:
> 
>      tsort input-file
>      if test $? -eq 1; then
>        echo do something
>      fi

I don't think that edge case is worth worrying about,
given tsort is less often used, and that's not a normal way to check errors.

So we could just always exit >= 125 on error, and
it would suffice to mention this in NEWS under "Change in behavior".

But I'm inclined to only do the exit status adjustments if -w was specified.
and just document the exit status range in the info docs for -w,
and no further changes to NEWS.

> If we can agree on that behavior, I'll probably move tests/misc/tsort.pl
> to a separate tsort directory in tests. And then add a shell script to
> test the behavior of POSIXLY_CORRECT on the exit status using /dev/full.

In general it's better to err on a separate dir per util.

thanks!
Padraig