[PATCH] submodule: check for NULL return of get_submodule_ref_store()

[Stefan Beller <sbeller@google.com>]

From: René Scharfe <l.s.r@web.de>

If we can't find a ref store for a submodule then assume it the latter
is not initialized (or was removed).  Print a status line accordingly
instead of causing a segmentation fault by passing NULL as the first
parameter of refs_head_ref().

Reported-by: Jeremy Feusi <jeremy@feusi.co>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Stefan Beller <sbeller@google.com>
---

I added a test for you.

Thanks,
Stefan

 builtin/submodule--helper.c |  8 ++++++--
 t/t7400-submodule-basic.sh  | 12 ++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index ee020d4749..ae3014ac5a 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -654,9 +654,13 @@ static void status_submodule(const char *path, const struct object_id *ce_oid,
 			     displaypath);
 	} else if (!(flags & OPT_CACHED)) {
 		struct object_id oid;
+		struct ref_store *refs = get_submodule_ref_store(path);
 
-		if (refs_head_ref(get_submodule_ref_store(path),
-				  handle_submodule_head_ref, &oid))
+		if (!refs) {
+			print_status(flags, '-', path, ce_oid, displaypath);
+			goto cleanup;
+		}
+		if (refs_head_ref(refs, handle_submodule_head_ref, &oid))
 			die(_("could not resolve HEAD ref inside the "
 			      "submodule '%s'"), path);
 
diff --git a/t/t7400-submodule-basic.sh b/t/t7400-submodule-basic.sh
index a39e69a3eb..d8aee51603 100755
--- a/t/t7400-submodule-basic.sh
+++ b/t/t7400-submodule-basic.sh
@@ -821,6 +821,18 @@ test_expect_success 'moving the superproject does not break submodules' '
 	)
 '
 
+test_expect_success 'moving the submodule does not break the superproject' '
+	(
+		cd addtest2 &&
+
+		mv repo repo.bak &&
+		git submodule status >actual &&
+		grep -e "^-" -e repo actual &&
+
+		mv repo.bak repo
+	)
+'
+
 test_expect_success 'submodule add --name allows to replace a submodule with another at the same path' '
 	(
 		cd addtest2 &&
-- 
2.17.0.rc1.321.gba9d0f2565-goog