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From: Emily Shaffer <emilyshaffer@google.com>
To: git@vger.kernel.org
Cc: Emily Shaffer <emilyshaffer@google.com>,
	Junio C Hamano <gitster@pobox.com>
Subject: [PATCH v6 2/5] introduce submodule.superprojectGitDir record
Date: Tue, 16 Nov 2021 16:56:58 -0800	[thread overview]
Message-ID: <20211117005701.371808-3-emilyshaffer@google.com> (raw)
In-Reply-To: <20211117005701.371808-1-emilyshaffer@google.com>

Teach submodules a reference to their superproject's gitdir. This allows
us to A) know that we're running from a submodule, and B) have a
shortcut to the superproject's vitals, for example, configs.

By using a relative path instead of an absolute path, we can move the
superproject directory around on the filesystem without breaking the
submodule's pointer. And by using the path from gitdir to gitdir, we can
move the submodule within the superproject's tree structure without
breaking the submodule's pointer, too. Finally, by pointing at the
superproject's worktree gitdir (if it exists), we ensure that we can
tell which worktree contains our submodule.

Since this hint value is only introduced during new submodule creation
via `git submodule add`, though, there is more work to do to allow the
record to be created at other times.

Once this new config is reliably in place, we can use it to know
definitively that we are working in a submodule, and to know which
superproject we are a submodule of. This allows us to do some
value-added behavior, like letting "git status" print additional info
about the submodule's status in relation to its superproject, or like
letting the superproject and submodule share an additional config file
separate from either one's local config.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/config/submodule.txt | 12 +++++++++++
 builtin/submodule--helper.c        | 11 ++++++++++
 t/t7400-submodule-basic.sh         | 32 ++++++++++++++++++++----------
 3 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/Documentation/config/submodule.txt b/Documentation/config/submodule.txt
index ee454f8126..61d975745e 100644
--- a/Documentation/config/submodule.txt
+++ b/Documentation/config/submodule.txt
@@ -91,3 +91,15 @@ submodule.alternateErrorStrategy::
 	`ignore`, `info`, `die`. Default is `die`. Note that if set to `ignore`
 	or `info`, and if there is an error with the computed alternate, the
 	clone proceeds as if no alternate was specified.
+
+submodule.superprojectGitDir::
+	The relative path from the submodule's gitdir to its superproject's
+	gitdir. When Git is run in a repository, it usually makes no
+	difference whether this repository is standalone or a submodule, but if
+	this configuration variable is present, additional behavior may be
+	possible, such as "git status" printing additional information about
+	this submodule's status with respect to its superproject. This config
+	should only be present in projects which are submodules, but is not
+	guaranteed to be present in every submodule, so only optional
+	value-added behavior should be linked to it. It is set automatically
+	during submodule creation.
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index e630f0c730..24f0ef2a78 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -1838,6 +1838,17 @@ static int clone_submodule(struct module_clone_data *clone_data)
 		git_config_set_in_file(p, "submodule.alternateErrorStrategy",
 				       error_strategy);
 
+	/*
+	 * Set the path from submodule's new gitdir to superproject's gitdir.
+	 * The latter may be a worktree gitdir. However, it is not possible for
+	 * the submodule to have a worktree-specific gitdir or config at clone
+	 * time, because "extensions.worktreeConfig" is only valid when set in
+	 * the local gitconfig, which the brand new submodule does not have yet.
+	 */
+	git_config_set_in_file(p, "submodule.superprojectGitDir",
+			       relative_path(absolute_path(get_git_dir()),
+					     sm_gitdir, &sb));
+
 	free(sm_alternate);
 	free(error_strategy);
 
diff --git a/t/t7400-submodule-basic.sh b/t/t7400-submodule-basic.sh
index d69a5c0032..3d146491df 100755
--- a/t/t7400-submodule-basic.sh
+++ b/t/t7400-submodule-basic.sh
@@ -109,12 +109,24 @@ submodurl=$(pwd -P)
 
 inspect() {
 	sub_dir=$1 &&
+	super_dir=$2 &&
 
 	git -C "$sub_dir" for-each-ref --format='%(refname)' 'refs/heads/*' >heads &&
 	{ git -C "$sub_dir" symbolic-ref HEAD || :; } >head &&
 	git -C "$sub_dir" rev-parse HEAD >head-sha1 &&
 	git -C "$sub_dir" update-index --refresh &&
 	git -C "$sub_dir" diff-files --exit-code &&
+
+	# Ensure that submodule.superprojectGitDir contains the path from the
+	# submodule's gitdir to the superproject's gitdir.
+
+	super_abs_gitdir=$(git -C "$super_dir" rev-parse --absolute-git-dir) &&
+	sub_abs_gitdir=$(git -C "$sub_dir" rev-parse --absolute-git-dir) &&
+
+	[ "$(git -C "$sub_dir" config --get submodule.superprojectGitDir)" = \
+	  "$(test-tool path-utils relative_path "$super_abs_gitdir" \
+						"$sub_abs_gitdir")" ] &&
+
 	git -C "$sub_dir" clean -n -d -x >untracked
 }
 
@@ -138,7 +150,7 @@ test_expect_success 'submodule add' '
 	) &&
 
 	rm -f heads head untracked &&
-	inspect addtest/submod &&
+	inspect addtest/submod addtest &&
 	test_cmp expect heads &&
 	test_cmp expect head &&
 	test_must_be_empty untracked
@@ -240,7 +252,7 @@ test_expect_success 'submodule add --branch' '
 	) &&
 
 	rm -f heads head untracked &&
-	inspect addtest/submod-branch &&
+	inspect addtest/submod-branch addtest &&
 	test_cmp expect-heads heads &&
 	test_cmp expect-head head &&
 	test_must_be_empty untracked
@@ -256,7 +268,7 @@ test_expect_success 'submodule add with ./ in path' '
 	) &&
 
 	rm -f heads head untracked &&
-	inspect addtest/dotsubmod/frotz &&
+	inspect addtest/dotsubmod/frotz addtest &&
 	test_cmp expect heads &&
 	test_cmp expect head &&
 	test_must_be_empty untracked
@@ -272,7 +284,7 @@ test_expect_success 'submodule add with /././ in path' '
 	) &&
 
 	rm -f heads head untracked &&
-	inspect addtest/dotslashdotsubmod/frotz &&
+	inspect addtest/dotslashdotsubmod/frotz addtest &&
 	test_cmp expect heads &&
 	test_cmp expect head &&
 	test_must_be_empty untracked
@@ -288,7 +300,7 @@ test_expect_success 'submodule add with // in path' '
 	) &&
 
 	rm -f heads head untracked &&
-	inspect addtest/slashslashsubmod/frotz &&
+	inspect addtest/slashslashsubmod/frotz addtest &&
 	test_cmp expect heads &&
 	test_cmp expect head &&
 	test_must_be_empty untracked
@@ -304,7 +316,7 @@ test_expect_success 'submodule add with /.. in path' '
 	) &&
 
 	rm -f heads head untracked &&
-	inspect addtest/realsubmod &&
+	inspect addtest/realsubmod addtest &&
 	test_cmp expect heads &&
 	test_cmp expect head &&
 	test_must_be_empty untracked
@@ -320,7 +332,7 @@ test_expect_success 'submodule add with ./, /.. and // in path' '
 	) &&
 
 	rm -f heads head untracked &&
-	inspect addtest/realsubmod2 &&
+	inspect addtest/realsubmod2 addtest &&
 	test_cmp expect heads &&
 	test_cmp expect head &&
 	test_must_be_empty untracked
@@ -351,7 +363,7 @@ test_expect_success 'submodule add in subdirectory' '
 	) &&
 
 	rm -f heads head untracked &&
-	inspect addtest/realsubmod3 &&
+	inspect addtest/realsubmod3 addtest &&
 	test_cmp expect heads &&
 	test_cmp expect head &&
 	test_must_be_empty untracked
@@ -492,7 +504,7 @@ test_expect_success 'update should work when path is an empty dir' '
 	git submodule update -q >update.out &&
 	test_must_be_empty update.out &&
 
-	inspect init &&
+	inspect init . &&
 	test_cmp expect head-sha1
 '
 
@@ -551,7 +563,7 @@ test_expect_success 'update should checkout rev1' '
 	echo "$rev1" >expect &&
 
 	git submodule update init &&
-	inspect init &&
+	inspect init . &&
 
 	test_cmp expect head-sha1
 '
-- 
2.34.0.rc1.387.gb447b232ab-goog


  parent reply	other threads:[~2021-11-17  0:57 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-17  0:56 [PATCH v6 0/5] teach submodules to know they're submodules Emily Shaffer
2021-11-17  0:56 ` [PATCH v6 1/5] t7400-submodule-basic: modernize inspect() helper Emily Shaffer
2021-11-17  0:56 ` Emily Shaffer [this message]
2021-11-17 23:43   ` [PATCH v6 2/5] introduce submodule.superprojectGitDir record Jonathan Tan
2021-11-17  0:56 ` [PATCH v6 3/5] submodule: record superproject gitdir during absorbgitdirs Emily Shaffer
2021-11-17  0:57 ` [PATCH v6 4/5] submodule: record superproject gitdir during 'update' Emily Shaffer
2021-11-17  0:57 ` [PATCH v6 5/5] submodule: use config to find superproject worktree Emily Shaffer
2021-11-17 11:43 ` [RFC PATCH 0/2] submodule: test what happens if submodule.superprojectGitDir isn't around Ævar Arnfjörð Bjarmason
2021-11-17 11:43   ` [RFC PATCH 1/2] submodule tests: fix potentially broken "config .. --unset" Ævar Arnfjörð Bjarmason
2021-11-17 11:43   ` [RFC PATCH 2/2] submodule: add test mode for checking absence of "superProjectGitDir" Ævar Arnfjörð Bjarmason
2021-11-23 20:08   ` [RFC PATCH 0/2] submodule: test what happens if submodule.superprojectGitDir isn't around Emily Shaffer
2021-11-24  1:38     ` Ævar Arnfjörð Bjarmason
2021-11-17 23:28 ` [PATCH v6 0/5] teach submodules to know they're submodules Jonathan Tan
2021-11-23 20:28   ` Emily Shaffer
2022-02-03 21:59 ` Emily Shaffer
2022-02-03 21:59   ` [PATCH v7 1/4] t7400-submodule-basic: modernize inspect() helper Emily Shaffer
2022-02-03 21:59   ` [PATCH v7 2/4] introduce submodule.superprojectGitDir record Emily Shaffer
2022-02-03 21:59   ` [PATCH v7 3/4] submodule: record superproject gitdir during absorbgitdirs Emily Shaffer
2022-02-03 21:59   ` [PATCH v7 4/4] submodule: record superproject gitdir during 'update' Emily Shaffer
2022-02-03 22:39   ` [PATCH v6 0/5] teach submodules to know they're submodules Junio C Hamano
2022-02-04  1:15   ` Ævar Arnfjörð Bjarmason
2022-02-04 16:20     ` Junio C Hamano
2022-02-07 19:56     ` Jonathan Nieder
2022-02-07 23:21       ` Junio C Hamano
2022-02-08  1:18         ` Jonathan Nieder
2022-02-08 18:24           ` Junio C Hamano
2022-02-10 22:12             ` Emily Shaffer
2022-02-10 22:53               ` Jonathan Nieder
2022-02-12 20:35       ` Ævar Arnfjörð Bjarmason
2022-02-13  6:25         ` Junio C Hamano
2022-03-01  0:26   ` [PATCH v8 0/3] " Emily Shaffer
2022-03-01  0:26     ` [PATCH v8 1/3] t7400-submodule-basic: modernize inspect() helper Emily Shaffer
2022-03-01  0:26     ` [PATCH v8 2/3] introduce submodule.hasSuperproject record Emily Shaffer
2022-03-01  7:00       ` Junio C Hamano
2022-03-08 20:04         ` Emily Shaffer
2022-03-08 22:13       ` Glen Choo
2022-03-08 22:29         ` Glen Choo
2022-03-01  0:26     ` [PATCH v8 3/3] rev-parse: short-circuit superproject worktree when config unset Emily Shaffer
2022-03-01  7:06       ` Junio C Hamano
2022-03-09  0:38         ` Emily Shaffer
2022-03-01  3:08     ` [PATCH v8 0/3] teach submodules to know they're submodules Junio C Hamano
2022-03-08 18:54       ` Emily Shaffer
2022-03-10  0:44     ` [PATCH v9 " Emily Shaffer
2022-03-10  0:44       ` [PATCH v9 1/3] t7400-submodule-basic: modernize inspect() helper Emily Shaffer
2022-03-10  0:44       ` [PATCH v9 2/3] introduce submodule.hasSuperproject record Emily Shaffer
2022-03-10  2:09         ` Junio C Hamano
2022-03-10 21:29           ` Glen Choo
2022-03-10 21:40           ` Glen Choo
2022-03-10 22:10             ` Junio C Hamano
2022-03-10 23:42               ` Glen Choo
2022-03-10 23:53                 ` Glen Choo
2022-03-15 20:48                   ` Emily Shaffer
2022-03-15 20:56                     ` Emily Shaffer
2022-03-15 21:19                       ` Glen Choo
2022-03-15 18:39               ` Emily Shaffer
2022-03-15 19:19                 ` Junio C Hamano
2022-03-10  2:32         ` Junio C Hamano
2022-03-10 21:54         ` Glen Choo
2022-03-15 18:27           ` Emily Shaffer
2022-03-10  0:44       ` [PATCH v9 3/3] rev-parse: short-circuit superproject worktree when config unset Emily Shaffer
2022-03-10  1:47         ` Junio C Hamano
2022-03-10  4:39           ` Eric Sunshine
2022-03-11  9:09       ` [PATCH v9 0/3] teach submodules to know they're submodules Ævar Arnfjörð Bjarmason
2022-03-13  5:43         ` Junio C Hamano

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