FWIW, there was a similar issue fixed in rpki-client somewhat
recently, for reference:
https://github.com/rpki-client/rpki-client-portable/pull/85

On Sat, Jun 24, 2023 at 9:50 PM Stefan Sperling <stsp@stsp.name> wrote:
>
> On Sat, Jun 24, 2023 at 10:32:52PM +0200, Christian Weisgerber wrote:
> > On FreeBSD, HOST_NAME_MAX is not defined.  Use _POSIX_HOST_NAME_MAX
> > instead, which is guaranteed to exist.
> >
> > OK?
> >
> > The POSIX logic is convoluted.  Basically, if I understand correctly:
> > If sysconf(_SC_HOST_NAME_MAX) >= _POSIX_HOST_NAME_MAX, then
> > HOST_NAME_MAX should not be defined in <limits.h>.
>
> Thanks for digging this up.
> I don't understand why it was specified like this in POSIX but everything
> still builds and works for me with this patch. So fine by me.
>
> > -----------------------------------------------
> > commit 1f948a3aee6f3f9bff26b7f39fe2c4e63ddf8ff6 (main)
> > from: Christian Weisgerber <naddy@mips.inka.de>
> > date: Sat Jun 24 20:25:37 2023 UTC
> >
> >  use _POSIX_HOST_NAME_MAX for portability
> >
> >  M  lib/repository_admin.c
> >
> > diff 294fdcae50063512dd68a933836696c9eb0ea0ff 1f948a3aee6f3f9bff26b7f39fe2c4e63ddf8ff6
> > commit - 294fdcae50063512dd68a933836696c9eb0ea0ff
> > commit + 1f948a3aee6f3f9bff26b7f39fe2c4e63ddf8ff6
> > blob - 31425fb8310125b7f7fe7389432f6a005df42136
> > blob + b3f6f17b931df0ad083fed1158a332673f844866
> > --- lib/repository_admin.c
> > +++ lib/repository_admin.c
> > @@ -618,7 +618,7 @@ got_repo_cleanup_prepare(struct got_repository *repo,
> >      struct got_lockfile **lk)
> >  {
> >       const struct got_error *err;
> > -     char myname[HOST_NAME_MAX + 1];
> > +     char myname[_POSIX_HOST_NAME_MAX + 1];
> >
> >       if (gethostname(myname, sizeof(myname)) == -1)
> >               return got_error_from_errno("gethostname");
> >
> > --
> > Christian "naddy" Weisgerber                          naddy@mips.inka.de
> >
> >
>