[PATCH 3/4] submodule.c: get superprojects gitlink value

[Stefan Beller]

Signed-off-by: Stefan Beller <sbel...@google.com>
---
 submodule.c | 27 +++++++++++++++++++++++++++
 submodule.h |  6 ++++++
 2 files changed, 33 insertions(+)

diff --git a/submodule.c b/submodule.c
index 4fcb64469e..68b123eb13 100644
--- a/submodule.c
+++ b/submodule.c
@@ -2074,6 +2074,33 @@ const char *get_superproject_working_tree(void)
        return ret;
 }
 
+/*
+ * Returns 0 when the gitlink is found in the superprojects index,
+ * the value will be found in `oid`. Otherwise return -1.
+ */
+int get_superproject_gitlink(struct object_id *oid)
+{
+       struct child_process cp = CHILD_PROCESS_INIT;
+       struct strbuf sb = STRBUF_INIT;
+       const char *hash;
+
+       if (start_ls_files_dot_dot(&cp, &sb) < 0)
+               return -1;
+
+       if (!skip_prefix(sb.buf, "160000 ", &hash))
+               /*
+                * superproject doesn't have a gitlink at submodule position or
+                * output is gibberish
+                */
+               return -1;
+
+       if (get_oid_hex(hash, oid))
+               /* could not parse the object name */
+               return -1;
+
+       return 0;
+}
+
 /*
  * Put the gitdir for a submodule (given relative to the main
  * repository worktree) into `buf`, or return -1 on error.
diff --git a/submodule.h b/submodule.h
index f0da0277a4..5fc602f0c7 100644
--- a/submodule.h
+++ b/submodule.h
@@ -137,4 +137,10 @@ extern void absorb_git_dir_into_superproject(const char 
*prefix,
  */
 extern const char *get_superproject_working_tree(void);
 
+/*
+ * Returns 0 when the gitlink is found in the superprojects index,
+ * the value will be found in `oid`. Otherwise return -1.
+ */
+extern int get_superproject_gitlink(struct object_id *oid);
+
 #endif
-- 
2.15.0.128.g40905b34bf.dirty