Subject: [PATCH v2 1/3] fsck: verify commit graph when implicitly enabled

From: Glen Choo <[email-masked]>
Date: Fri, 17 Sep 2021 15:54:57 -0700

the_repository->settings is the preferred way to get certain
settings (such as "core.commitGraph") because it gets default values
from prepare_repo_settings(). However, cmd_fsck() reads the config
directly via git_config_get_bool(), which bypasses these default values.
This causes fsck to ignore the commit graph if "core.commitgraph" is not
explicitly set in the config. This worked fine until commit-graph was
enabled by default in 31b1de6a09 (commit-graph: turn on commit-graph by
default, 2019-08-13).

Replace git_config_get_bool("core.commitgraph") in fsck with the
equivalent call to the_repository->settings.core_commit_graph.

The expected behavior is that fsck respects the config value when it is
set, but uses the default value when it is unset. For example, for
core.commitGraph, there are three cases:

- Config value is set to true -> enabled
- Config value is set to false -> disabled
- Config value is unset -> enabled

As such, tests cover all three cases.

Signed-off-by: Glen Choo <[email-masked]>
---
 builtin/fsck.c          |  3 ++-
 t/t5318-commit-graph.sh | 24 +++++++++++++++++++++++-
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/builtin/fsck.c b/builtin/fsck.c
index b42b6fe21f..1c4e485b66 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -803,6 +803,7 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 		fsck_enable_object_names(&fsck_walk_options);
 
 	git_config(git_fsck_config, &fsck_obj_options);
+	prepare_repo_settings(the_repository);
 
 	if (connectivity_only) {
 		for_each_loose_object(mark_loose_for_connectivity, NULL, 0);
@@ -908,7 +909,7 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 
 	check_connectivity();
 
-	if (!git_config_get_bool("core.commitgraph", &i) && i) {
+	if (the_repository->settings.core_commit_graph) {
 		struct child_process commit_graph_verify = CHILD_PROCESS_INIT;
 		const char *verify_argv[] = { "commit-graph", "verify", NULL, NULL, NULL };
 
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index af88f805aa..42e785cb6e 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -674,7 +674,7 @@ test_expect_success 'detect incorrect chunk count' '
 		$GRAPH_CHUNK_LOOKUP_OFFSET
 '
 
-test_expect_success 'git fsck (checks commit-graph)' '
+test_expect_success 'git fsck (checks commit-graph when config set to true)' '
 	cd "$TRASH_DIRECTORY/full" &&
 	git fsck &&
 	corrupt_graph_and_verify $GRAPH_BYTE_FOOTER "\00" \
@@ -683,6 +683,28 @@ test_expect_success 'git fsck (checks commit-graph)' '
 	test_must_fail git fsck
 '
 
+test_expect_success 'git fsck (ignores commit-graph when config set to false)' '
+	cd "$TRASH_DIRECTORY/full" &&
+	git fsck &&
+	corrupt_graph_and_verify $GRAPH_BYTE_FOOTER "\00" \
+		"incorrect checksum" &&
+	cp commit-graph-pre-write-test $objdir/info/commit-graph &&
+	test_config core.commitGraph false &&
+	git fsck
+'
+
+test_expect_success 'git fsck (checks commit-graph when config unset)' '
+	test_when_finished "git config core.commitGraph true" &&
+
+	cd "$TRASH_DIRECTORY/full" &&
+	git fsck &&
+	corrupt_graph_and_verify $GRAPH_BYTE_FOOTER "\00" \
+		"incorrect checksum" &&
+	test_unconfig core.commitGraph &&
+	cp commit-graph-pre-write-test $objdir/info/commit-graph &&
+	test_must_fail git fsck
+'
+
 test_expect_success 'setup non-the_repository tests' '
 	rm -rf repo &&
 	git init repo &&
-- 
2.33.0.464.g1972c5931b-goog