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[PATCH v4 2/4] introduce submodule.superprojectGitDir record

From
Emily Shaffer <emilyshaffer@google.com>
Date
Oct 14, 2021, 20:34 UTC
Message-ID
<20211014203416.2802639-3-emilyshaffer@google.com>
In-Reply-To
<20211014203416.2802639-1-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 cache. 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 cache, too.

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.

If the new config is present, we can do some optional 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        |  4 ++++
 t/t7400-submodule-basic.sh         | 32 ++++++++++++++++++++----------
 3 files changed, 38 insertions(+), 10 deletions(-)
diff --git a/Documentation/config/submodule.txt b/Documentation/config/submodule.txt
index ee454f8126..c10aeb7fdc 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 d574d650af..338dcbd364 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -1838,6 +1838,10 @@ static int clone_submodule(struct module_clone_data *clone_data)
 		git_config_set_in_file(p, "submodule.alternateErrorStrategy",
 				       error_strategy);
 
+	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
 '

-- 
2.33.0.1079.g6e70778dc9-goog
Previous: Emily ShafferNext: Emily Shaffer
Message 3 of 31 in “cache parent project's gitdir in submodules”
  1. 0/4 cache parent project's gitdir in submodulesEmily Shaffer, Oct 14, 2021
  2. 1/4 t7400-submodule-basic: modernize inspect() helperEmily Shaffer, Oct 14, 2021
  3. 2/4 introduce submodule.superprojectGitDir recordEmily Shaffer, Oct 14, 2021
  4. 3/4 submodule: record superproject gitdir during absorbgitdirsEmily Shaffer, Oct 14, 2021
  5. Jonathan TanOct 18, 2021
  6. Derrick StoleeOct 25, 2021
  7. Emily ShafferNov 4, 2021
  8. Derrick StoleeNov 8, 2021
  9. Emily ShafferNov 4, 2021
  10. 4/4 submodule: record superproject gitdir during 'update'Emily Shaffer, Oct 14, 2021
  11. Derrick StoleeOct 25, 2021
  12. Derrick StoleeOct 25, 2021
  13. 0/4 cache parent project's gitdir in submodulesEmily Shaffer, Nov 4, 2021
  14. 1/4 t7400-submodule-basic: modernize inspect() helperEmily Shaffer, Nov 4, 2021
  15. 2/4 introduce submodule.superprojectGitDir recordEmily Shaffer, Nov 4, 2021
  16. Junio C HamanoNov 5, 2021
  17. Emily ShafferNov 8, 2021
  18. 3/4 submodule: record superproject gitdir during absorbgitdirsEmily Shaffer, Nov 4, 2021
  19. 4/4 submodule: record superproject gitdir during 'update'Emily Shaffer, Nov 4, 2021
  20. Junio C HamanoNov 5, 2021
  21. Ævar Arnfjörð BjarmasonNov 5, 2021
  22. Emily ShafferNov 8, 2021
  23. Ævar Arnfjörð BjarmasonNov 9, 2021
  24. Emily ShafferNov 9, 2021
  25. Emily ShafferNov 9, 2021
  26. Ævar Arnfjörð BjarmasonNov 5, 2021
  27. Emily ShafferNov 8, 2021
  28. Ævar Arnfjörð BjarmasonNov 9, 2021
  29. Derrick StoleeNov 8, 2021
  30. Emily ShafferNov 8, 2021
  31. Derrick StoleeNov 9, 2021

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