refs: extract out `refs_create_refdir_stubs()`

For Git to recognize a directory as a Git directory, it requires the
directory to contain:

  1. 'HEAD' file
  2. 'objects/' directory
  3. 'refs/' directory

Here, #1 and #3 are part of the reference storage mechanism,
specifically the files backend. Since then, newer backends such as the
reftable backend have moved to using their own path ('reftable/') for
storing references. But to ensure Git still recognizes the directory as
a Git directory, we create stubs.

There are two locations where we create stubs:

- In 'refs/reftable-backend.c' when creating the reftable backend.
- In 'clone.c' before spawning transport helpers.

In a following commit, we'll add another instance. So instead of
repeating the code, let's extract out this code to
`refs_create_refdir_stubs()` and use it.

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/refs.c b/refs.c
index 627b7f8698..77b93d655b 100644
--- a/refs.c
+++ b/refs.c
@@ -2163,6 +2163,29 @@ const char *refs_resolve_ref_unsafe(struct ref_store *refs,
 	return NULL;
 }
 
+void refs_create_refdir_stubs(struct repository *repo, const char *refdir,
+			      const char *refs_heads_content)
+{
+	struct strbuf path = STRBUF_INIT;
+
+	strbuf_addf(&path, "%s/HEAD", refdir);
+	write_file(path.buf, "ref: refs/heads/.invalid");
+	adjust_shared_perm(repo, path.buf);
+
+	strbuf_reset(&path);
+	strbuf_addf(&path, "%s/refs", refdir);
+	safe_create_dir(repo, path.buf, 1);
+
+	if (refs_heads_content) {
+		strbuf_reset(&path);
+		strbuf_addf(&path, "%s/refs/heads", refdir);
+		write_file(path.buf, "%s", refs_heads_content);
+		adjust_shared_perm(repo, path.buf);
+	}
+
+	strbuf_release(&path);
+}
+
 /* backend functions */
 int ref_store_create_on_disk(struct ref_store *refs, int flags, struct strbuf *err)
 {