From: Matheus Tavares Bernardino <matheus.bernardino@usp.br>
To: Thomas Gummerer <t.gummerer@gmail.com>
Cc: git <git@vger.kernel.org>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Christian Couder" <christian.couder@gmail.com>,
"Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>,
"Kernel USP" <kernel-usp@googlegroups.com>,
"Benoit Pierre" <benoit.pierre@gmail.com>,
"Junio C Hamano" <gitster@pobox.com>,
"Johannes Schindelin" <Johannes.Schindelin@gmx.de>
Subject: Re: [GSoC][PATCH v4 2/7] clone: better handle symlinked files at .git/objects/
Date: Fri, 29 Mar 2019 11:27:54 -0300 [thread overview]
Message-ID: <CAHd-oW78Cwhq8sFFjOX4c6kS8JsEUUd_RGgheJhdN6MLAr+G2Q@mail.gmail.com> (raw)
In-Reply-To: <20190328221049.GK32487@hank.intra.tgummerer.com>
On Thu, Mar 28, 2019 at 7:10 PM Thomas Gummerer <t.gummerer@gmail.com> wrote:
>
> On 03/22, Matheus Tavares wrote:
> > There is currently an odd behaviour when locally clonning a repository
> > with symlinks at .git/objects: using --no-hardlinks all symlinks are
> > dereferenced but without it Git will try to hardlink the files with the
> > link() function, which has an OS-specific behaviour on symlinks. On OSX
> > and NetBSD, it creates a hardlink to the file pointed by the symlink
> > whilst on GNU/Linux, it creates a hardlink to the symlink itself.
> >
> > On Manjaro GNU/Linux:
> > $ touch a
> > $ ln -s a b
> > $ link b c
> > $ ls -li a b c
> > 155 [...] a
> > 156 [...] b -> a
> > 156 [...] c -> a
> >
> > But on NetBSD:
> > $ ls -li a b c
> > 2609160 [...] a
> > 2609164 [...] b -> a
> > 2609160 [...] c
> >
> > It's not good to have the result of a local clone to be OS-dependent and
> > since the behaviour on GNU/Linux may result in broken symlinks, let's
> > re-implement it with linkat() instead of link() using a flag to always
> > follow symlinks and make the hardlink be to the pointed file. With this,
> > besides standardizing the behaviour, no broken symlinks will be
> > produced. Also, add tests for symlinked files at .git/objects/.
> >
> > Note: Git won't create symlinks at .git/objects itself, but it's better
> > to handle this case and be friendly with users who manually create them.
> >
> > Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
> > Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> > Co-authored-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> > ---
> > builtin/clone.c | 2 +-
> > t/t5604-clone-reference.sh | 26 +++++++++++++++++++-------
> > 2 files changed, 20 insertions(+), 8 deletions(-)
> >
> > diff --git a/builtin/clone.c b/builtin/clone.c
> > index 50bde99618..b76f33c635 100644
> > --- a/builtin/clone.c
> > +++ b/builtin/clone.c
> > @@ -443,7 +443,7 @@ static void copy_or_link_directory(struct strbuf *src, struct strbuf *dest,
> > if (unlink(dest->buf) && errno != ENOENT)
> > die_errno(_("failed to unlink '%s'"), dest->buf);
> > if (!option_no_hardlinks) {
> > - if (!link(src->buf, dest->buf))
> > + if (!linkat(AT_FDCWD, src->buf, AT_FDCWD, dest->buf, AT_SYMLINK_FOLLOW))
>
> This line is starting to get a bit long, might be worth breaking it up
> to keep to 80 characters per line.
>
> I notice that we are currently not using 'linkat()' anywhere else in
> our codebase. It looks like it has been introduced in POSIX.1-2008,
> which sounds fairly recent by git's standards. So I wonder if this is
> really supported on all platforms that git is being built on.
>
> I also wonder what would need to be done on Windows if we were to
> introduce this. I see we define the 'link()' function in
> 'compat/mingw.c' for that currently, so I guess something similar
> would be needed for 'linkat()'. I added Dscho to Cc for Windows
> expertise.
Ok, what if instead of using linkat() we use 'realpath(const char
*path, char *resolved_path)', which will resolve any symlinks at
'path' and store the canonical path at 'resolved_path'? Then, we can
still keep using link() but now, with the certainty that all platforms
will have a consistent behaviour? (also, realpath() is POSIX.1-2001)
Would that be a better idea?
> While I agree with the goal of consistency accross all platforms here,
> I don't know if it's actually worth going through the pain of doing
> that, especially for somewhat of an edge case in local clones.
>
> If the test in the previous patch passes on all platforms, I'd be okay
> with just calling the behaviour here undefined, especially as git
> would never actually create symlinks in the .git/objects directory.
next prev parent reply other threads:[~2019-03-29 14:28 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-26 5:17 [WIP RFC PATCH v2 0/5] clone: dir iterator refactoring with tests Matheus Tavares
2019-02-26 5:18 ` [WIP RFC PATCH v2 1/5] dir-iterator: add flags parameter to dir_iterator_begin Matheus Tavares
2019-02-26 12:01 ` Duy Nguyen
2019-02-27 13:59 ` Matheus Tavares Bernardino
2019-02-26 5:18 ` [WIP RFC PATCH v2 2/5] clone: test for our behavior on odd objects/* content Matheus Tavares
2019-02-26 5:18 ` [WIP RFC PATCH v2 3/5] clone: copy hidden paths at local clone Matheus Tavares
2019-02-26 12:13 ` Duy Nguyen
2019-02-26 5:18 ` [WIP RFC PATCH v2 4/5] clone: extract function from copy_or_link_directory Matheus Tavares
2019-02-26 12:18 ` Duy Nguyen
2019-02-27 17:30 ` Matheus Tavares Bernardino
2019-02-27 22:45 ` Thomas Gummerer
2019-02-27 22:50 ` Matheus Tavares Bernardino
2019-02-26 5:18 ` [WIP RFC PATCH v2 5/5] clone: use dir-iterator to avoid explicit dir traversal Matheus Tavares
2019-02-26 11:35 ` Ævar Arnfjörð Bjarmason
2019-02-26 12:32 ` Duy Nguyen
2019-02-26 12:50 ` Ævar Arnfjörð Bjarmason
2019-02-27 17:40 ` Matheus Tavares Bernardino
2019-02-28 7:13 ` Duy Nguyen
2019-02-28 7:53 ` Ævar Arnfjörð Bjarmason
2019-02-26 11:36 ` [WIP RFC PATCH v2 0/5] clone: dir iterator refactoring with tests Ævar Arnfjörð Bjarmason
2019-02-26 12:20 ` Duy Nguyen
2019-02-26 12:28 ` [RFC PATCH v3 " Ævar Arnfjörð Bjarmason
2019-02-26 20:56 ` Matheus Tavares Bernardino
2019-03-22 23:22 ` [GSoC][PATCH v4 0/7] clone: dir-iterator " Matheus Tavares
2019-03-22 23:22 ` [GSoC][PATCH v4 1/7] clone: test for our behavior on odd objects/* content Matheus Tavares
2019-03-24 18:09 ` Matheus Tavares Bernardino
2019-03-24 20:56 ` SZEDER Gábor
2019-03-26 19:43 ` Matheus Tavares Bernardino
2019-03-28 21:49 ` Thomas Gummerer
2019-03-29 14:06 ` Matheus Tavares Bernardino
2019-03-29 19:31 ` Thomas Gummerer
2019-03-29 19:42 ` SZEDER Gábor
2019-03-30 2:49 ` Matheus Tavares Bernardino
2019-03-22 23:22 ` [GSoC][PATCH v4 2/7] clone: better handle symlinked files at .git/objects/ Matheus Tavares
2019-03-28 22:10 ` Thomas Gummerer
2019-03-29 8:38 ` Ævar Arnfjörð Bjarmason
2019-03-29 20:15 ` Thomas Gummerer
2019-03-29 14:27 ` Matheus Tavares Bernardino [this message]
2019-03-29 20:05 ` Thomas Gummerer
2019-03-30 5:32 ` Matheus Tavares Bernardino
2019-03-30 19:27 ` Thomas Gummerer
2019-04-01 3:56 ` Matheus Tavares Bernardino
2019-03-29 15:40 ` Johannes Schindelin
2019-03-22 23:22 ` [GSoC][PATCH v4 3/7] dir-iterator: add flags parameter to dir_iterator_begin Matheus Tavares
2019-03-28 22:19 ` Thomas Gummerer
2019-03-29 13:16 ` Matheus Tavares Bernardino
2019-03-22 23:22 ` [GSoC][PATCH v4 4/7] clone: copy hidden paths at local clone Matheus Tavares
2019-03-22 23:22 ` [GSoC][PATCH v4 5/7] clone: extract function from copy_or_link_directory Matheus Tavares
2019-03-22 23:22 ` [GSoC][PATCH v4 6/7] clone: use dir-iterator to avoid explicit dir traversal Matheus Tavares
2019-03-22 23:22 ` [GSoC][PATCH v4 7/7] clone: Replace strcmp by fspathcmp Matheus Tavares
2019-03-30 22:49 ` [GSoC][PATCH v5 0/7] clone: dir-iterator refactoring with tests Matheus Tavares
2019-03-30 22:49 ` [GSoC][PATCH v5 1/7] clone: test for our behavior on odd objects/* content Matheus Tavares
2019-03-30 22:49 ` [GSoC][PATCH v5 2/7] clone: better handle symlinked files at .git/objects/ Matheus Tavares
2019-03-31 17:40 ` Thomas Gummerer
2019-04-01 3:59 ` Matheus Tavares Bernardino
2019-03-30 22:49 ` [GSoC][PATCH v5 3/7] dir-iterator: add flags parameter to dir_iterator_begin Matheus Tavares
2019-03-31 18:12 ` Thomas Gummerer
2019-04-10 20:24 ` Matheus Tavares Bernardino
2019-04-11 21:09 ` Thomas Gummerer
2019-04-23 17:07 ` Matheus Tavares Bernardino
2019-04-24 18:36 ` Thomas Gummerer
2019-04-26 4:13 ` Matheus Tavares Bernardino
2019-03-30 22:49 ` [GSoC][PATCH v5 4/7] clone: copy hidden paths at local clone Matheus Tavares
2019-03-30 22:49 ` [GSoC][PATCH v5 5/7] clone: extract function from copy_or_link_directory Matheus Tavares
2019-03-30 22:49 ` [GSoC][PATCH v5 6/7] clone: use dir-iterator to avoid explicit dir traversal Matheus Tavares
2019-03-30 22:49 ` [GSoC][PATCH v5 7/7] clone: replace strcmp by fspathcmp Matheus Tavares
2019-03-31 18:16 ` [GSoC][PATCH v5 0/7] clone: dir-iterator refactoring with tests Thomas Gummerer
2019-04-01 13:56 ` Matheus Tavares Bernardino
2019-05-02 14:48 ` [GSoC][PATCH v6 00/10] " Matheus Tavares
2019-05-02 14:48 ` [GSoC][PATCH v6 01/10] clone: test for our behavior on odd objects/* content Matheus Tavares
2019-05-02 14:48 ` [GSoC][PATCH v6 02/10] clone: better handle symlinked files at .git/objects/ Matheus Tavares
2019-05-02 14:48 ` [GSoC][PATCH v6 03/10] dir-iterator: add tests for dir-iterator API Matheus Tavares
2019-05-02 14:48 ` [GSoC][PATCH v6 04/10] dir-iterator: use warning_errno when possible Matheus Tavares
2019-05-02 14:48 ` [GSoC][PATCH v6 05/10] dir-iterator: refactor state machine model Matheus Tavares
2019-05-02 14:48 ` [GSoC][PATCH v6 06/10] dir-iterator: add flags parameter to dir_iterator_begin Matheus Tavares
2019-05-02 14:48 ` [GSoC][PATCH v6 07/10] clone: copy hidden paths at local clone Matheus Tavares
2019-05-02 14:48 ` [GSoC][PATCH v6 08/10] clone: extract function from copy_or_link_directory Matheus Tavares
2019-05-02 14:48 ` [GSoC][PATCH v6 09/10] clone: use dir-iterator to avoid explicit dir traversal Matheus Tavares
2019-05-02 14:48 ` [GSoC][PATCH v6 10/10] clone: replace strcmp by fspathcmp Matheus Tavares
2019-06-18 23:27 ` [GSoC][PATCH v7 00/10] clone: dir-iterator refactoring with tests Matheus Tavares
2019-06-18 23:27 ` [GSoC][PATCH v7 01/10] clone: test for our behavior on odd objects/* content Matheus Tavares
2019-06-18 23:27 ` [GSoC][PATCH v7 02/10] clone: better handle symlinked files at .git/objects/ Matheus Tavares
2019-06-18 23:27 ` [GSoC][PATCH v7 03/10] dir-iterator: add tests for dir-iterator API Matheus Tavares
2019-06-18 23:27 ` [GSoC][PATCH v7 04/10] dir-iterator: use warning_errno when possible Matheus Tavares
2019-06-18 23:27 ` [GSoC][PATCH v7 05/10] dir-iterator: refactor state machine model Matheus Tavares
2019-06-18 23:27 ` [GSoC][PATCH v7 06/10] dir-iterator: add flags parameter to dir_iterator_begin Matheus Tavares
2019-06-25 18:00 ` Junio C Hamano
2019-06-25 18:11 ` Matheus Tavares Bernardino
2019-06-26 13:34 ` Johannes Schindelin
2019-06-26 18:04 ` Junio C Hamano
2019-06-27 9:20 ` Duy Nguyen
2019-06-27 17:23 ` Matheus Tavares Bernardino
2019-06-27 18:48 ` Johannes Schindelin
2019-06-27 19:33 ` Matheus Tavares Bernardino
2019-06-28 12:51 ` Johannes Schindelin
2019-06-28 14:16 ` Matheus Tavares Bernardino
2019-07-01 12:15 ` Johannes Schindelin
2019-07-03 8:57 ` SZEDER Gábor
2019-07-08 22:21 ` Matheus Tavares Bernardino
2019-06-18 23:27 ` [GSoC][PATCH v7 07/10] clone: copy hidden paths at local clone Matheus Tavares
2019-06-18 23:27 ` [GSoC][PATCH v7 08/10] clone: extract function from copy_or_link_directory Matheus Tavares
2019-06-18 23:27 ` [GSoC][PATCH v7 09/10] clone: use dir-iterator to avoid explicit dir traversal Matheus Tavares
2019-06-18 23:27 ` [GSoC][PATCH v7 10/10] clone: replace strcmp by fspathcmp Matheus Tavares
2019-06-19 4:36 ` [GSoC][PATCH v7 00/10] clone: dir-iterator refactoring with tests Matheus Tavares Bernardino
2019-06-20 20:18 ` Junio C Hamano
2019-06-21 13:41 ` Matheus Tavares Bernardino
2019-07-10 23:58 ` [GSoC][PATCH v8 " Matheus Tavares
2019-07-10 23:58 ` [GSoC][PATCH v8 01/10] clone: test for our behavior on odd objects/* content Matheus Tavares
2019-07-10 23:58 ` [GSoC][PATCH v8 02/10] clone: better handle symlinked files at .git/objects/ Matheus Tavares
2019-07-10 23:58 ` [GSoC][PATCH v8 03/10] dir-iterator: add tests for dir-iterator API Matheus Tavares
2019-07-10 23:58 ` [GSoC][PATCH v8 04/10] dir-iterator: use warning_errno when possible Matheus Tavares
2019-07-10 23:58 ` [GSoC][PATCH v8 05/10] dir-iterator: refactor state machine model Matheus Tavares
2019-07-10 23:59 ` [GSoC][PATCH v8 06/10] dir-iterator: add flags parameter to dir_iterator_begin Matheus Tavares
2019-07-10 23:59 ` [GSoC][PATCH v8 07/10] clone: copy hidden paths at local clone Matheus Tavares
2019-07-10 23:59 ` [GSoC][PATCH v8 08/10] clone: extract function from copy_or_link_directory Matheus Tavares
2019-07-10 23:59 ` [GSoC][PATCH v8 09/10] clone: use dir-iterator to avoid explicit dir traversal Matheus Tavares
2019-07-10 23:59 ` [GSoC][PATCH v8 10/10] clone: replace strcmp by fspathcmp Matheus Tavares
2019-07-11 11:56 ` [GSoC][PATCH v8 00/10] clone: dir-iterator refactoring with tests Johannes Schindelin
2019-07-11 15:24 ` Matheus Tavares Bernardino
2019-02-26 12:28 ` [RFC PATCH v3 1/5] clone: test for our behavior on odd objects/* content Ævar Arnfjörð Bjarmason
2019-02-28 21:19 ` Matheus Tavares Bernardino
2019-03-01 13:49 ` Ævar Arnfjörð Bjarmason
2019-03-13 3:17 ` Matheus Tavares
2019-02-26 12:28 ` [RFC PATCH v3 2/5] dir-iterator: add flags parameter to dir_iterator_begin Ævar Arnfjörð Bjarmason
2019-02-26 12:28 ` [RFC PATCH v3 3/5] clone: copy hidden paths at local clone Ævar Arnfjörð Bjarmason
2019-02-26 12:28 ` [RFC PATCH v3 4/5] clone: extract function from copy_or_link_directory Ævar Arnfjörð Bjarmason
2019-02-26 12:28 ` [RFC PATCH v3 5/5] clone: use dir-iterator to avoid explicit dir traversal Ævar Arnfjörð Bjarmason
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