Re: [PATCH] dir: point treat_leading_path() warning to the right place

From: Elijah Newren <newren@gmail.com>
To: Jeff King <peff@peff.net>
Cc: Elijah Newren via GitGitGadget <gitgitgadget@gmail.com>,
	Junio C Hamano <gitster@pobox.com>,
	Git Mailing List <git@vger.kernel.org>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>
Subject: Re: [PATCH] dir: point treat_leading_path() warning to the right place
Date: Wed, 15 Jan 2020 12:28:48 -0800	[thread overview]
Message-ID: <CABPp-BFQDkpcm57dTwH+AiMsocxTro4ZuvhK2eAZzfHutWjq3Q@mail.gmail.com> (raw)
In-Reply-To: <20200115202146.GA4091171@coredump.intra.peff.net>

On Wed, Jan 15, 2020 at 12:21 PM Jeff King <peff@peff.net> wrote:
>
> On Wed, Jan 15, 2020 at 02:21:18PM +0000, Elijah Newren via GitGitGadget wrote:
>
> > From: Jeff King <peff@peff.net>
> >
> > Restructure the code slightly to avoid passing around a struct dirent
> > anywhere, which also enables us to avoid trying to manufacture one.
> >
> > Signed-off-by: Jeff King <peff@peff.net>
> > Signed-off-by: Elijah Newren <newren@gmail.com>
>
> Thanks, this looks good.
>
> I wondered briefly whether this:
>
> > @@ -2374,12 +2362,13 @@ static int treat_leading_path(struct dir_struct *dir,
> >                       break;
> >               strbuf_reset(&sb);
> >               strbuf_add(&sb, path, prevlen);
> > -             memcpy(de->d_name, path+prevlen, baselen-prevlen);
> > -             de->d_name[baselen-prevlen] = '\0';
> > +             strbuf_reset(&subdir);
> > +             strbuf_add(&subdir, path+prevlen, baselen-prevlen);
> > +             cdir.d_name = subdir.buf;
>
> ...could avoid the extra strbuf by pointing into an existing string
> (since d_name is now a pointer, and not part of a dirent). But I think
> the answer is "no", because in a path like "a/b/c", the loop may see
> just "b" (so offsetting into path isn't sufficient, because we also have
> to cut off the trailing part).
>
> I did notice one other small thing while looking at this code:
>
> -- >8 --
> Subject: [PATCH] dir: point treat_leading_path() warning to the right place
>
> Commit 777b420347 (dir: synchronize treat_leading_path() and
> read_directory_recursive(), 2019-12-19) tried to add two warning
> comments in those functions, pointing at each other. But the one in
> treat_leading_path() just points at itself.
>
> Let's fix that. Since the comment also redirects the reader for more
> details to "the commit that added this warning", and since we're now
> modifying the warning (creating a new commit without those details),
> let's mention the actual commit id.
>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
>  dir.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/dir.c b/dir.c
> index 7d255227b1..31e83d982a 100644
> --- a/dir.c
> +++ b/dir.c
> @@ -2308,9 +2308,9 @@ static int treat_leading_path(struct dir_struct *dir,
>          * WARNING WARNING WARNING:
>          *
>          * Any updates to the traversal logic here may need corresponding
> -        * updates in treat_leading_path().  See the commit message for the
> -        * commit adding this warning as well as the commit preceding it
> -        * for details.
> +        * updates in read_directory_recursive().  See 777b420347 (dir:
> +        * synchronize treat_leading_path() and read_directory_recursive(),
> +        * 2019-12-19) and its parent commit for details.
>          */
>
>         struct strbuf sb = STRBUF_INIT;
> --
> 2.25.0.639.gb9b1511416

Looks good to me; thanks.