fsck: verify multi-pack-index

When core.multiPackIndex is true, we may have a multi-pack-index
in our object directory. Add calls to 'git multi-pack-index verify'
at the end of 'git fsck' if so.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/fsck.c

@@ -848,5 +848,23 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 		}
 	}
 
+	if (!git_config_get_bool("core.multipackindex", &i) && i) {
+		struct child_process midx_verify = CHILD_PROCESS_INIT;
+		const char *midx_argv[] = { "multi-pack-index", "verify", NULL, NULL, NULL };
+
+		midx_verify.argv = midx_argv;
+		midx_verify.git_cmd = 1;
+		if (run_command(&midx_verify))
+			errors_found |= ERROR_COMMIT_GRAPH;
+
+		prepare_alt_odb(the_repository);
+		for (alt =  the_repository->objects->alt_odb_list; alt; alt = alt->next) {
+			midx_argv[2] = "--object-dir";
+			midx_argv[3] = alt->path;
+			if (run_command(&midx_verify))
+				errors_found |= ERROR_COMMIT_GRAPH;
+		}
+	}
+
 	return errors_found;
 }

t/t5319-multi-pack-index.sh

@@ -160,12 +160,17 @@ corrupt_midx_and_verify() {
 	DATA="${2:-\0}" &&
 	OBJDIR=$3 &&
 	GREPSTR="$4" &&
+	COMMAND="$5" &&
+	if test -z "$COMMAND"
+	then
+		COMMAND="git multi-pack-index verify --object-dir=$OBJDIR"
+	fi &&
 	FILE=$OBJDIR/pack/multi-pack-index &&
 	chmod a+w $FILE &&
 	test_when_finished mv midx-backup $FILE &&
 	cp $FILE midx-backup &&
 	printf "$DATA" | dd of="$FILE" bs=1 seek="$POS" conv=notrunc &&
-	test_must_fail git multi-pack-index verify --object-dir=$OBJDIR 2>test_err &&
+	test_must_fail $COMMAND 2>test_err &&
 	grep -v "^+" test_err >err &&
 	test_i18ngrep "$GREPSTR" err
 }
@@ -258,6 +263,12 @@ test_expect_success 'verify incorrect offset' '
 		"incorrect object offset"
 '
 
+test_expect_success 'git-fsck incorrect offset' '
+	corrupt_midx_and_verify $MIDX_BYTE_OFFSET "\07" $objdir \
+		"incorrect object offset" \
+		"git -c core.multipackindex=true fsck"
+'
+
 test_expect_success 'repack removes multi-pack-index' '
 	test_path_is_file $objdir/pack/multi-pack-index &&
 	git repack -adf &&