Junio C Hamano <gitster@xxxxxxxxx> 于2022年7月12日周二 06:11写道：
>
> "ZheNing Hu via GitGitGadget" <gitgitgadget@xxxxxxxxx> writes:
>
> > From: ZheNing Hu <adlternative@xxxxxxxxx>
> >
> > Add a new option --format that output index enties ...
>
> Let's quote the options and use the Oxford comma.
>
> ls-files: introduce "--format" option
>
> Add a new option "--format" that outputs index entries in a
> custom format, taking inspiration from the option with the same
> name in the `git ls-tree` command.
>
> "--format" cannot used with "-s", "-o", "-k", "-t", "--resolve-undo",
> "--deduplicate", and "--eol".
>
> > +It is possible to print in a custom format by using the `--format`
> > +option, which is able to interpolate different fields using
>
> So we use the term "field" to mean different piece of information we
> can present. The definition of what fields are available come later
> and the presentation order is a bit awkward, but hopefully the text
> is understandable as-is.
>
OK.
> > +a `%(fieldname)` notation. For example, if you only care about the
> > +"objectname" and "path" fields, you can execute with a specific
> > +"--format" like
> > +
> > + git ls-files --format='%(objectname) %(path)'
>
> And the example makes it pretty clear. OK.
>
> > +FIELD NAMES
> > +-----------
> > +Various values from structured fields can be used to interpolate
>
> Are we dealing with unstructured fields, too? If not, let's drop
> "structured".
>
OK (copy from git-ls-tree.txt too)
> > +into the resulting output. For each outputting line, the following
> > +names can be used:
>
> "outputting line" sounds like a non language.
>
>
> The way each path is shown can be customized by using the
> `--format=<format>` option, where the %(fieldname) in the
> <format> string for various aspects of the index entry are
> interpolated. The following "fieldname" are understood:
>
> perhaps?
>
This will indeed be better.
> > +{
> > + struct show_index_data *data = context;
> > + const char *end;
> > + const char *p;
> > + size_t len = strbuf_expand_literal_cb(sb, start, NULL);
> > + struct stat st;
> > +
> > + if (len)
> > + return len;
> > + if (*start != '(')
> > + die(_("bad ls-files format: element '%s' "
> > + "does not start with '('"), start);
> > +
> > + end = strchr(start + 1, ')');
> > + if (!end)
> > + die(_("bad ls-files format: element '%s'"
> > + "does not end in ')'"), start);
> > +
> > + len = end - start + 1;
> > + if (skip_prefix(start, "(objectmode)", &p))
>
>
> Using skip_prefix() not for the purpose of skipping (notice that
> nobody uses p at all) is ugly. We already computed start and end
> (hence the length), so we should be able to do much better than
> this.
>
Agree. I check the parsing format part of ref-filter.c, we just need to find the
atom's begin pos and end pos, then we can use memcmp() to know what's the
type of atom.
> But let's let it pass, as it was copy-pasted from existing code in
> ls-tree.c::expand_show_tree().
>
Yeah, maybe we can optimize it later.
> > + else if (skip_prefix(start, "(eolinfo:index)", &p) &&
> > + S_ISREG(data->ce->ce_mode))
> > + strbuf_addstr(sb, get_cached_convert_stats_ascii(data->istate,
> > + data->ce->name));
>
> This is outright wrong, isn't it?
>
> It is unlikely to see such a trivial error in the 6th round of a
> series after other reviewers looked at it many times, so perhaps I
> am missing something? Or perhaps this is a new code added in this
> round.
>
> If you ask for %(eolinfo:index) for an index entry that is not a
> regular file, this "else if" will not trigger, and the control will
> eventually fall through to hit "bad ls-files format" but what you
> detected is not a bad format at all. Once the skip_prefix() hits,
> you should be committed to handle that "field" and never let the
> other choices in this if/elif/ cascade to see it.
>
> It is OK to interpolate %(eolinfo:index) to an empty string for a
> gitlink and a symbolic link, but the right way to do so would
> probably be:
>
> else if (skip_prefix(start, "(eolinfo:index)", &p) {
> if (S_ISREG(data->ce->ce_mode))
> strbuf_addstr(...);
> } else ...
>
Yeah, but we would use "{", "}" again, so just revert this code to v5,
which uses a
wrap function.
> > + else if (skip_prefix(start, "(eolinfo:worktree)", &p) &&
> > + !lstat(data->pathname, &st) && S_ISREG(st.st_mode))
> > + strbuf_addstr(sb, get_wt_convert_stats_ascii(data->pathname));
>
> Likewise.
>
> > +test_expect_success 'setup' '
> > + echo o1 >o1 &&
> > + echo o2 >o2 &&
> > + git add o1 o2 &&
> > + git add --chmod +x o1 &&
> > + git commit -m base
> > +'
>
> Apparently, this set-up is too trivial to uncover the above bug that
> can be spotted in 10 seconds of staring at the code. Perhaps add a
> symbolic link (use "git update-index --cacheinfo" and you do not
> have to worry about Windows), a subdirectory and a submodule?
>
Ah, Just looking at the c code, I took a long time (more than 10 minutes) to
find out where the mistake was. But yeah, use a subdirectory can quickly
meet the error, so I need to add more cases here.
Thanks for your review.
ZheNing Hu
