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From: Stefan Beller <sbeller@google.com>
To: Antonio Ospite <ao2@ao2.it>
Cc: SZEDER Gábor <szeder.dev@gmail.com>,
	Junio C Hamano <gitster@pobox.com>, git <git@vger.kernel.org>,
	Brandon Williams <bmwill@google.com>,
	Daniel Graña <dangra@gmail.com>,
	Jonathan Nieder <jrnieder@gmail.com>,
	Richard Hartmann <richih.mailinglist@gmail.com>,
	Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Subject: Re: [PATCH v5 9/9] submodule: support reading .gitmodules when it's not in the working tree
Date: Mon, 24 Sep 2018 14:00:50 -0700
Message-ID: <CAGZ79kZaomuE3p1puznM1x+hu-w4O+ZqeGUODBDj=-R3Z1hDzg@mail.gmail.com> (raw)
In-Reply-To: <20180924122031.9dbec6b4c2e2a8c1bff3365b@ao2.it>

On Mon, Sep 24, 2018 at 3:20 AM Antonio Ospite <ao2@ao2.it> wrote:

> > The third call, however, looks at the nested submodule at
> > 'submodule/sub', which doesn't contain a '.gitmodules' file.  So this
> > function goes on with the second condition and calls
> > get_oid(GITMODULES_INDEX, &oid), which then appears to find the blob
> > in the _superproject's_ index.
> >
>
> You are correct.
>
> This is a limitation of the object store in git, there is no equivalent
> of get_oid() to get the oid from a specific repository and this affects
> config_with_options too when the config source is a blob.

Not yet, as there is a big push to pass-through an object-store object
or similar recently and rely less on global variables.
I am not sure I get to this code, though.

> This does not affect commands called via "git -C submodule_dir cmd"
> because in that case the chdir happens before the_repository is set up,
> for instance "git-submodule $SOMETHING --recursive" commands seem to
> change the working directory before the recursion.

For this it may be worth looking into the option
       --super-prefix=<path>
  Currently for internal use only. Set a prefix which gives a
  path from above a repository down to its root. One use is
  to give submodules context about the superproject that
  invoked it.

the whole motion of moving to in-process deprecates this clunky
API to pass around strings to subprocesses.

> The test suite passes even after removing repo_read_gitmodules()
> entirely from builtin/grep.c, but I am still not confident that I get
> all the implication of why that call was originally added in commit
> f9ee2fcdfa (grep: recurse in-process using 'struct repository',
> 2017-08-02).

If you checkout that commit and remove the call to repo_read_gitmodules
and then call git-grep in a superproject with nested submodules, you
get a segfault.

On master (and deleting out that line) you do not get the segfault,
I think praise goes to ff6f1f564c4 (submodule-config: lazy-load a
repository's .gitmodules file, 2017-08-03) which happened shortly
after f9ee2fcdfa.

It showcased that it worked by converting ls-files, but left out grep.

So I think based on ff6f1f564c4 it is safe to remove all calls to
repo_read_gitmodules.

> Anyways, even if we removed the call we would prevent the problem from
> happening in the test suite, but not in the real world, in case non-leaf
> submodules without .gitmodules in their working tree.

Quite frankly I think grep was just overlooked in review of
https://public-inbox.org/git/20170803182000.179328-14-bmwill@google.com/

Stefan

  reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-17 14:09 [PATCH v5 0/9] Make submodules work if .gitmodules is not checked out Antonio Ospite
2018-09-17 14:09 ` [PATCH v5 1/9] submodule: add a print_config_from_gitmodules() helper Antonio Ospite
2018-09-24 10:25   ` Antonio Ospite
2018-09-24 23:06     ` Stefan Beller
2018-09-17 14:09 ` [PATCH v5 2/9] submodule: factor out a config_set_in_gitmodules_file_gently function Antonio Ospite
2018-09-17 14:09 ` [PATCH v5 3/9] t7411: merge tests 5 and 6 Antonio Ospite
2018-09-17 14:09 ` [PATCH v5 4/9] t7411: be nicer to future tests and really clean things up Antonio Ospite
2018-09-17 14:09 ` [PATCH v5 5/9] submodule--helper: add a new 'config' subcommand Antonio Ospite
2018-09-17 14:09 ` [PATCH v5 6/9] submodule: use the 'submodule--helper config' command Antonio Ospite
2018-09-17 14:09 ` [PATCH v5 7/9] t7506: clean up .gitmodules properly before setting up new scenario Antonio Ospite
2018-09-17 14:09 ` [PATCH v5 8/9] submodule: add a helper to check if it is safe to write to .gitmodules Antonio Ospite
2018-09-17 14:09 ` [PATCH v5 9/9] submodule: support reading .gitmodules when it's not in the working tree Antonio Ospite
2018-09-18 17:12   ` SZEDER Gábor
2018-09-19 19:24     ` Junio C Hamano
2018-09-20 15:35     ` Antonio Ospite
2018-09-21 16:19       ` Junio C Hamano
2018-09-27 14:49         ` Antonio Ospite
2018-09-24 10:20     ` Antonio Ospite
2018-09-24 21:00       ` Stefan Beller [this message]
2018-09-27 14:44         ` Antonio Ospite
2018-09-27 18:00           ` Stefan Beller
2018-10-01 15:45             ` Antonio Ospite
2018-10-01 19:42               ` Stefan Beller

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