[PATCH 1/5] submodules: add helper functions to determine presence of submodules

[Brandon Williams <bmwill@google.com>]

Add two helper functions to submodules.c.
`is_submodule_initialized()` checks if a submodule has been initialized
at a given path and `is_submodule_checked_out()` check if a submodule
has been checked out at a given path.

Signed-off-by: Brandon Williams <bmwill@google.com>
---
 submodule.c | 39 +++++++++++++++++++++++++++++++++++++++
 submodule.h |  2 ++
 2 files changed, 41 insertions(+)

diff --git a/submodule.c b/submodule.c
index 6f7d883de..029b24440 100644
--- a/submodule.c
+++ b/submodule.c
@@ -198,6 +198,45 @@ void gitmodules_config(void)
 	}
 }
 
+/*
+ * Determine if a submodule has been initialized at a given 'path'
+ */
+int is_submodule_initialized(const char *path)
+{
+	int ret = 0;
+	const struct submodule *module = NULL;
+
+	module = submodule_from_path(null_sha1, path);
+
+	if (module) {
+		struct strbuf buf = STRBUF_INIT;
+		char *submodule_url = NULL;
+
+		strbuf_addf(&buf, "submodule.%s.url",module->name);
+		ret = !git_config_get_string(buf.buf, &submodule_url);
+
+		free(submodule_url);
+		strbuf_release(&buf);
+	}
+
+	return ret;
+}
+
+/*
+ * Determine if a submodule has been checked out at a given 'path'
+ */
+int is_submodule_checked_out(const char *path)
+{
+	int ret = 0;
+	struct strbuf buf = STRBUF_INIT;
+
+	strbuf_addf(&buf, "%s/.git", path);
+	ret = file_exists(buf.buf);
+
+	strbuf_release(&buf);
+	return ret;
+}
+
 int parse_submodule_update_strategy(const char *value,
 		struct submodule_update_strategy *dst)
 {
diff --git a/submodule.h b/submodule.h
index d9e197a94..bd039ca98 100644
--- a/submodule.h
+++ b/submodule.h
@@ -37,6 +37,8 @@ void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,
 		const char *path);
 int submodule_config(const char *var, const char *value, void *cb);
 void gitmodules_config(void);
+extern int is_submodule_initialized(const char *path);
+extern int is_submodule_checked_out(const char *path);
 int parse_submodule_update_strategy(const char *value,
 		struct submodule_update_strategy *dst);
 const char *submodule_strategy_to_string(const struct submodule_update_strategy *s);
-- 
2.10.1.613.g6021889