From 627fde102515a7807dba89acaa88cb053b38a44a Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Mon, 24 Apr 2017 20:57:47 -0400
Subject: submodule_init: die cleanly on submodules without url defined

When we init a submodule, we try to die when it has no URL
defined:

  url = xstrdup(sub->url);
  if (!url)
	  die(...);

But that's clearly nonsense. xstrdup() will never return
NULL, and if sub->url is NULL, we'll segfault.

These two bits of code need to be flipped, so we check
sub->url before looking at it.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 926d205..b345689 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -332,12 +332,12 @@ static void init_submodule(const char *path, const char *prefix, int quiet)
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "submodule.%s.url", sub->name);
 	if (git_config_get_string(sb.buf, &url)) {
-		url = xstrdup(sub->url);
-
-		if (!url)
+		if (!sub->url)
 			die(_("No url found for submodule path '%s' in .gitmodules"),
 				displaypath);
 
+		url = xstrdup(sub->url);
+
 		/* Possibly a url relative to parent */
 		if (starts_with_dot_dot_slash(url) ||
 		    starts_with_dot_slash(url)) {
diff --git a/t/t7400-submodule-basic.sh b/t/t7400-submodule-basic.sh
index 3570f7b..01e25a4 100755
--- a/t/t7400-submodule-basic.sh
+++ b/t/t7400-submodule-basic.sh
@@ -38,6 +38,14 @@ test_expect_success 'submodule update aborts on missing .gitmodules file' '
 	test_i18ngrep "Submodule path .sub. not initialized" actual
 '
 
+test_expect_success 'submodule update aborts on missing gitmodules url' '
+	test_when_finished "git update-index --remove sub" &&
+	git update-index --add --cacheinfo 160000,$(git rev-parse HEAD),sub &&
+	test_when_finished "rm -f .gitmodules" &&
+	git config -f .gitmodules submodule.s.path sub &&
+	test_must_fail git submodule init
+'
+
 test_expect_success 'configuration parsing' '
 	test_when_finished "rm -f .gitmodules" &&
 	cat >.gitmodules <<-\EOF &&
-- 
cgit v0.10.2-6-g49f6