Re: [PATCH] symbolic-ref: check format of given reference

On Tue, Jun 19, 2012 at 10:47:12AM -0400, Jeff King wrote:

On Mon, Jun 18, 2012 at 10:10:14AM -0700, Junio C Hamano wrote:

quoted

For that matter, shouldn't symbolic-ref be forbidden to point
outside refs/heads/, not just restricted in refs/ like the current
code does?

We tried that already but reverted it due to topgit. See:

    commit e9cc02f0e41fd5d2f51e3c3f2b4f8cfa9e434432
    Author: Jeff King [off-list ref]
    Date:   Fri Feb 13 13:26:09 2009 -0500

        symbolic-ref: allow refs/<whatever> in HEAD

        Commit afe5d3d5 introduced a safety valve to symbolic-ref to
        disallow installing an invalid HEAD. It was accompanied by
        b229d18a, which changed validate_headref to require that
        HEAD contain a pointer to refs/heads/ instead of just refs/.
        Therefore, the safety valve also checked for refs/heads/.

        As it turns out, topgit is using refs/top-bases/ in HEAD,
        leading us to re-loosen (at least temporarily) the
        validate_headref check made in b229d18a. This patch does the
        corresponding loosening for the symbolic-ref safety valve,
        so that the two are in agreement once more.

The "at least temporarily" in that commit message merited a little
investigation. There was some discussion of changing topgit to record
its information using a different scheme, but there was no clear
outcome:

  http://thread.gmane.org/gmane.comp.version-control.git/109581

So if somebody wanted to re-tighten this check, they would want
to at least check topgit's current behavior, and see which versions of
it we would be breaking. I tend to think it is not worth the effort.

-Peff