[PATCH 3/7] submodule: is_submodule_active to differentiate between new and old mode

[Stefan Beller <sbeller@google.com>]

The change a086f921a72 (submodule: decouple url and submodule interest,
2017-03-17) enables us to do more than originally thought.
As the url setting was used both to actually set the url where to
obtain the submodule from, as well as used as a boolean flag later
to see if it was active, we would need to keep the url around.

Now that submodules can be activated using the submodule.[<name>.]active
setting, we could remove the url if the submodule is activated via that
setting.

In preparation to do so, pave the way by providing an easy way to see
if a submodule is considered active via the new .active setting or via
the old .url setting.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 submodule.c | 5 +----
 submodule.h | 6 ++++++
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/submodule.c b/submodule.c
index 6e14547e9e0..d56350ed094 100644
--- a/submodule.c
+++ b/submodule.c
@@ -221,9 +221,6 @@ int option_parse_recurse_submodules_worktree_updater(const struct option *opt,
 	return 0;
 }
 
-/*
- * Determine if a submodule has been initialized at a given 'path'
- */
 int is_submodule_active(struct repository *repo, const char *path)
 {
 	int ret = 0;
@@ -267,7 +264,7 @@ int is_submodule_active(struct repository *repo, const char *path)
 
 	/* fallback to checking if the URL is set */
 	key = xstrfmt("submodule.%s.url", module->name);
-	ret = !repo_config_get_string(repo, key, &value);
+	ret = !repo_config_get_string(repo, key, &value) ? 2 : 0;
 
 	free(value);
 	free(key);
diff --git a/submodule.h b/submodule.h
index 4644683e6cb..bfc070e4629 100644
--- a/submodule.h
+++ b/submodule.h
@@ -45,6 +45,12 @@ extern int git_default_submodule_config(const char *var, const char *value, void
 struct option;
 int option_parse_recurse_submodules_worktree_updater(const struct option *opt,
 						     const char *arg, int unset);
+/*
+ * Determine if a submodule has been initialized at a given 'path'.
+ * Returns 1 if it is considered active via the submodule.[<name>.]active
+ * setting, or return 2 if it is active via the older submodule.url setting.
+ */
+#define SUBMODULE_ACTIVE_VIA_URL 2
 extern int is_submodule_active(struct repository *repo, const char *path);
 /*
  * Determine if a submodule has been populated at a given 'path' by checking if
-- 
2.18.0.265.g16de1b435c9.dirty