submodule: fetch missing objects from default remote

When be76c21282 (fetch: ensure submodule objects fetched, 2018-12-06)
added support for fetching a missing submodule object by id, it
hardcoded the remote name as "origin" and deferred anything more
complicated for a later patch. Implement the NEEDSWORK item to remove
the hardcoded assumption by adding and using a submodule helper subcmd
'get-default-remote'. Fixing this lets 'git fetch --recurse-submodules'
succeed when the fetched commit(s) in the superproject trigger a
submodule fetch, and that submodule's default remote name is not
"origin".

Add non-"origin" remote tests to t5526-fetch-submodules.sh and
t5572-pull-submodule.sh demonstrating this works as expected and add
dedicated tests for get-default-remote.

Signed-off-by: Nasser Grainawi <nasser.grainawi@oss.qualcomm.com>
Reviewed-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index d537ab087a..b180a24091 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -112,6 +112,43 @@ static int get_default_remote_submodule(const char *module_path, char **default_
 	return 0;
 }
 
+static int module_get_default_remote(int argc, const char **argv, const char *prefix,
+				     struct repository *repo UNUSED)
+{
+	const char *path;
+	char *resolved_path = NULL;
+	char *default_remote = NULL;
+	int code;
+	struct option options[] = {
+		OPT_END()
+	};
+	const char *const usage[] = {
+		N_("git submodule--helper get-default-remote <path>"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, options);
+
+	path = argv[0];
+	if (prefix && *prefix && !is_absolute_path(path)) {
+		resolved_path = xstrfmt("%s%s", prefix, path);
+		path = resolved_path;
+	}
+
+	code = get_default_remote_submodule(path, &default_remote);
+	if (code) {
+		free(resolved_path);
+		return code;
+	}
+
+	printf("%s\n", default_remote);
+	free(default_remote);
+	free(resolved_path);
+	return 0;
+}
+
 /* the result should be freed by the caller. */
 static char *get_submodule_displaypath(const char *path, const char *prefix,
 				       const char *super_prefix)
@@ -3608,6 +3645,7 @@ int cmd_submodule__helper(int argc,
 		OPT_SUBCOMMAND("set-url", &fn, module_set_url),
 		OPT_SUBCOMMAND("set-branch", &fn, module_set_branch),
 		OPT_SUBCOMMAND("create-branch", &fn, module_create_branch),
+		OPT_SUBCOMMAND("get-default-remote", &fn, module_get_default_remote),
 		OPT_END()
 	};
 	argc = parse_options(argc, argv, prefix, options, usage, 0);