Re: [PATCH 1/2] ref-filter: hacky "streaming" mode

[ZheNing Hu <adlternative@gmail.com>]

Jeff King <peff@peff.net> 于2021年9月8日周三 上午2:01写道：
>
> On Tue, Sep 07, 2021 at 01:28:33PM +0800, ZheNing Hu wrote:
>
> > > I think it's just because pretty_print_ref() does not take a "flag"
> > > parameter for the caller. So it never sees that REF_ISSYMREF is set.
> > >
> >
> > yeah, pretty_print_ref() does not set the flag, this is a defect of
> > pretty_print_ref(), maybe we need to find a way to set this flag.
>
> In general, I think it could take a flag parameter from its caller. But
> its caller comes indirectly from for_each_tag_name(), which isn't a
> regular ref-iterator. It would probably need to switch to using
> read_ref_full() to get the flags.
>

Yeah, I think using read_ref_full() with verify_tag() changes can
solve this BUG:

$ git.fix tag --verify --format='verify: %(refname) %(symref)' annotated symref
verify: refs/tags/annotated
verify: refs/tags/symref refs/tags/annotated

diff --git a/ref-filter.c b/ref-filter.c
index 1efa3aadc8..71b1d7da4f 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -2613,18 +2613,6 @@ void ref_filter_maybe_stream(struct ref_filter *filter,
        if (filter->reachable_from || filter->unreachable_from)
                return;

-       /*
-        * the %(symref) placeholder is broken with pretty_print_ref(),
-        * which our streaming code uses. I suspect this is a sign of breakage
-        * in other callers like verify_tag(), which should be fixed. But for
-        * now just disable streaming.
-        *
-        * Note that this implies we've parsed the format already with
-        * verify_ref_format().
-        */
-       if (need_symref)
-               return;
-
        /* OK to stream */
        filter->streaming_format = format;
 }
@@ -2735,6 +2723,7 @@ void pretty_print_ref(const char *name, const
struct object_id *oid,

        ref_item = new_ref_array_item(name, oid);
        ref_item->kind = ref_kind_from_refname(name);
+       read_ref_full(name, 0, NULL, &ref_item->flag);
        if (format_ref_array_item(ref_item, format, &output, &err))
                die("%s", err.buf);
        fwrite(output.buf, 1, output.len, stdout);

> > > I notice that the --verify output also shows the short refname, which
> > > makes me wonder if %(symref) would have other bugs there (because it
> > > has to re-resolve the ref to come up with the symref destination).
> > >
> >
> > This may be easy to fix:
> >
> > diff --git a/builtin/tag.c b/builtin/tag.c
> > index 452558ec95..4be5d36366 100644
> > --- a/builtin/tag.c
> > +++ b/builtin/tag.c
> > @@ -152,11 +152,11 @@ static int verify_tag(const char *name, const char *ref,
> >         if (format->format)
> >                 flags = GPG_VERIFY_OMIT_STATUS;
> >
> > -       if (gpg_verify_tag(oid, name, flags))
> > +       if (gpg_verify_tag(oid, ref, flags))
> >                 return -1;
> >
> >         if (format->format)
> > -               pretty_print_ref(name, oid, format);
> > +               pretty_print_ref(ref, oid, format);
> >
> >         return 0;
> >  }
>
> Yeah, I think that would work, although:
>
>   - there's another caller in cmd_verify_tag() which seems to just pass
>     whatever was on the command line. It doesn't even resolve the ref
>     itself!
>

We can modify get_oid() --> read_ref_full() in cmd_verify_tag()...
Yes, the inconsistency between cmd_verify_tag() and verify_tag() makes
me feel very strange.

>   - I suspect people may be relying on the current behavior. The
>     original was added to be able to compare the internal tagname to the
>     refname. I.e., that:
>
>       git tag -v --format='%(refname) %(tag)' foo
>
>     would show "foo foo". Now that _should_ be "%(refname:strip=2)", I
>     think, but we'd probably be breaking scripts. OTOH, it really feels
>     like _not_ handing over a real, fully-qualified refname to the
>     ref-filter code will mean other things are broken (e.g.,
>     ATOM_UPSTREAM is assuming we have a fully-qualified ref).
>

This is indeed a sad thing: A bug becomes a feature.

>     I think a backwards-compatible way of fixing it would be to have
>     this call hand over the full refname to the ref-filter code, but
>     tell it that %(refname) should default to strip=2. And then anybody
>     who wants the full name can use %(refname:strip=0).
>

Doesn't this make things more complicated? Those callers of git for-each-ref,
wouldn't our changes like this destroy them?


>     It makes the behavior confusing and quirky, but we can't avoid that
>     without breaking compatibility.
>

Eh, I think we may need other solutions.

> -Peff

Thanks.
--
ZheNing Hu