bug#64954: GNU 'uptime' on OpenBSD always prints "0 users"

[Pádraig Brady]

On 30/07/2023 15:44, Bruno Haible wrote:
> Hi,
>
> GNU coreutils-9.3 'uptime', on OpenBSD 7.2, prints
>
>   16:24:53  up 14 days 13:33,  0 users,  load average: 0.04, 0.44, 0.59
>
> whereas the OpenBSD /usr/bin/uptime prints
>
>   4:24PM  up 14 days, 13:33, 1 user, load averages: 0.04, 0.44, 0.59
>
> The utmp file contain these entries:
>
>      Time (GMT)           User          PID     Term Exit Boot User Process
> ------------------- --------------- ---------- ---- ---- ---- ------------
> 1970-01-01 00:00:00                          0   0    0
> 1970-01-01 00:00:00                          0   0    0
> 2023-07-16 00:52:00 bruno                    0   0    0
>
> The readutmp.h code, in particular the IS_USER_PROCESS macro, works fine.
> (UT_TYPE_USER_PROCESS (U) expands to 0, and UT_TYPE_NOT_DEFINED expands to 1.)
>
> The problem is that the readutmp code is entirely disabled on this platform.
> Which is not appropriate.
>
> When I revert the coreutils commit 2984e47c789ebc39f55a3b1cb20b943de88eeedc,
> the coreutils 'uptime' program prints "1 user", as expected.
>
> The rationale of that commit was wrong:
> "Following gnulib commit 9041103 HAVE_UTMP_H will always be defined."
> No, what that gnulib commit did is to create an <utmp.h> replacement
> if the package imports the 'login_tty' module. But the HAVE_UTMP_H
> is *still* only defined if the platform provides it.
> Proof: On FreeBSD 13.2, which does not have <utmp.h> (it has <utmpx.h>
> instead), configuring coreutils-9.3 produces the attached config.h,
> which has
>
> #define HAVE_UTMPX_H 1
> /* #undef HAVE_UTMP_H */
>
> So, find attached the fix of the bug.

I'm fine with the change, but we'll also need to adjust
the sc_prohibit_always_true_header_tests syntax check in gnulib
as that will fail since gnulib/lib/utmp.in.h is present
and thus use of HAVE_UTMP_H is disallowed.

cheers,
Pádraig