svn commit: r351423 - in head: . sbin/ping6 sbin/ping6/tests

[Hiroki Sato]

Hi Alan and Conrad,

 I agree with the idea having ping6(8) as a hardlink to ping(8) to
 provide the historical ping6(8) behavior.

Alan Somers <asomers at freebsd.org> wrote
  in <CAOtMX2hjaYq+8_S0yXeAJutF2gNy3wgivmvOd=OV-iTByUdYKA at mail.gmail.com>:

as> Jan (please keep him CCed on replies) has been musing about the same
as> thing.  That might satisfy everyone.  Jan, would it be straightforward
as> to implement?
as> -Alan
as> 
as> On Sun, Aug 25, 2019 at 5:51 PM Conrad Meyer <cem at freebsd.org> wrote:
as> >
as> > Hi Alan, Hiroki,
as> >
as> > It would be pretty easy to install a `ping6` link to the `ping(8)`
as> > binary with different option parsing (conditional on argv[0]).  That
as> > removes most of the issues of code and space duplication, I think?
as> > And the goal would be for the 'ping6' name to retain option
as> > compatibility with historical ping6.
as> >
as> > It's not an uncommon pattern; for example, 'id', 'groups', and
as> > 'whoami' are all a single binary with multiple linked names.  Another
as> > example is Clang, which provides 'cc', 'c++', 'clang', 'clang-cpp',
as> > 'clang++' and 'cpp' links to the same inode — and those have very
as> > different behavior depending on argv[0].
as> >
as> > It's less work than forcing the ping6 compatibility crowd to create a
as> > port and doesn't hurt ping(8) much, AFAICT.  Is it an acceptable
as> > middle ground?
as> >
as> > Best,
as> > Conrad
as> >
as> > On Sun, Aug 25, 2019 at 1:26 PM alan somers <asomers at gmail.com> wrote:
as> > >
as> > > On Sun, Aug 25, 2019, 2:11 PM Hiroki Sato <hrs at allbsd.org> wrote:
as> > >>
as> > >> Alan Somers <asomers at freebsd.org> wrote
as> > >>   in <CAOtMX2hLxx=SKvh1ZoiMAcagQJjPaRSvkML9J+BgpQsz5uNNbw at mail.gmail.com>:
as> > >>
as> > >> as> On Sun, Aug 25, 2019 at 1:22 PM Hiroki Sato <hrs at allbsd.org> wrote:
as> > >> as> >
as> > >> as> > Hi,
as> > >> as> >
as> > >> as> > Alan Somers <asomers at FreeBSD.org> wrote
as> > >> as> >   in <201908231522.x7NFMLuJ068037 at repo.freebsd.org>:
as> > >> as> >
as> > >> as> > as> Author: asomers
as> > >> as> > as> Date: Fri Aug 23 15:22:20 2019
as> > >> as> > as> New Revision: 351423
as> > >> as> > as> URL: https://svnweb.freebsd.org/changeset/base/351423
as> > >> as> > as>
as> > >> as> > as> Log:
as> > >> as> > as>   ping6: Rename options for better consistency with ping
as> > >> as> > as>
as> > >> as> > as>   Now equivalent options have the same flags, and nonequivalent options have
as> > >> as> > as>   different flags.  This is a prelude to merging the two commands.
as> > >> as> > as>
as> > >> as> > as>   Submitted by:     Ján Sučan <sucanjan at gmail.com>
as> > >> as> > as>   MFC:              Never
as> > >> as> > as>   Sponsored by:     Google LLC (Google Summer of Code 2019)
as> > >> as> > as>   Differential Revision:    https://reviews.freebsd.org/D21345
as> > >> as> >
as> > >> as> >  I have an objection on renaming the existing option flags in ping6(8)
as> > >> as> >  for compatibility with ping(8).
as> > >> as> >
as> > >> as> >  Is it sufficient to add INET6 support to ping(8) with consistent
as> > >> as> >  flags and keep CLI of ping6(8) backward compatible?  People have used
as> > >> as> >  ping6(8) for >15 years, so it is too late to rename the flags.  I do
as> > >> as> >  not think the renaming is useful if "ping -6 localhost" or "ping ::1"
as> > >> as> >  works.
as> > >> as> >
as> > >> as> > -- Hiroki
as> > >> as>
as> > >> as> If ping works with inet6, then why would we want to keep a separate
as> > >> as> tool around?  If it's just for the sake of people who don't want to or
as> > >> as> can't update scripts, would a version in ports suffice?
as> > >>
as> > >>  Because removing (or renaming) it causes a POLA violation.  Do we
as> > >>  really have a strong, unavoidable reason to force people to rewrite
as> > >>  their script now?  This is still a fairly essential and actively used
as> > >>  tool, not like rcp or rlogin.  Although deprecating ping6(8) and
as> > >>  removing it from the base system in the future release at some point
as> > >>  may work, changing the existing interface will simply confuse people
as> > >>  who have used IPv6 for a long time.
as> > >>
as> > >>  In my understanding, the purpose to integrate ping(8) and ping6(8)
as> > >>  into a single utility is to provide a consistent CLI and reduce
as> > >>  duplicate code, not to break compatibility.
as> > >>
as> > >> -- Hiroki
as> > >
as> > >
as> > > Those goals are incompatible. We can't provide a consistent CLI without breaking compatibility because ping and ping6 have conflicting options.  And we can't keep ping6 around while also removing duplicate code because that would be, well, duplicate code.
as> > >
as> > > When would be a better time than a major version bump to make a change like this?
as> > >
as> > > The lack of a ping6 command in freebsd 13 should serve as a pretty obvious reminder that scripts will need updating.  I think that putting a version of ping6 in ports should be a sufficient crutch for those who need it, don't you?
as> 
as> 

-- Hiroki
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