[PATCH v6 4/6] refs: move out stub modification to generic layer

[Karthik Nayak <karthik.188@gmail.com>]

When creating the reftable reference backend on disk, we create stubs to
ensure that the directory can be recognized as a Git repository. This is
done by calling `refs_create_refdir_stubs()`. Move this to the generic
layer as this is needed for all backends excluding from the files
backends. In an upcoming commit, we'll also need to extend this logic to
create stubs when using alternate reference directories.

Similarly, move the logic for deletion of stubs to the generic layer.
The files backend recursively calls the remove function of the
'packed-backend', here skip calling the generic function since that
would try to delete stubs.

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
---
 refs.c                  | 51 +++++++++++++++++++++++++++++++++++++++++++++++--
 refs/files-backend.c    |  6 +++++-
 refs/reftable-backend.c | 27 --------------------------
 3 files changed, 54 insertions(+), 30 deletions(-)

diff --git a/refs.c b/refs.c
index 11d028232b..a24602c9bf 100644
--- a/refs.c
+++ b/refs.c
@@ -2190,12 +2190,59 @@ void refs_create_refdir_stubs(struct repository *repo, const char *refdir,
 /* backend functions */
 int ref_store_create_on_disk(struct ref_store *refs, int flags, struct strbuf *err)
 {
-	return refs->be->create_on_disk(refs, flags, err);
+	int ret = refs->be->create_on_disk(refs, flags, err);
+
+	if (!ret &&
+	    ref_storage_format_by_name(refs->be->name) != REF_STORAGE_FORMAT_FILES) {
+		struct strbuf msg = STRBUF_INIT;
+
+		strbuf_addf(&msg, "this repository uses the %s format", refs->be->name);
+		refs_create_refdir_stubs(refs->repo, refs->gitdir, msg.buf);
+		strbuf_release(&msg);
+	}
+
+	return ret;
 }
 
 int ref_store_remove_on_disk(struct ref_store *refs, struct strbuf *err)
 {
-	return refs->be->remove_on_disk(refs, err);
+	int ret = refs->be->remove_on_disk(refs, err);
+
+	if (!ret) {
+		enum ref_storage_format format = ref_storage_format_by_name(refs->be->name);
+		struct strbuf sb = STRBUF_INIT;
+
+		/* Backends apart from the files backend create stubs. */
+		if (format == REF_STORAGE_FORMAT_FILES)
+			return ret;
+
+		strbuf_addf(&sb, "%s/HEAD", refs->gitdir);
+		if (unlink(sb.buf) < 0) {
+			strbuf_addf(err, "could not delete stub HEAD: %s",
+				    strerror(errno));
+			ret = -1;
+		}
+		strbuf_reset(&sb);
+
+		strbuf_addf(&sb, "%s/refs/heads", refs->gitdir);
+		if (unlink(sb.buf) < 0) {
+			strbuf_addf(err, "could not delete stub heads: %s",
+				    strerror(errno));
+			ret = -1;
+		}
+		strbuf_reset(&sb);
+
+		strbuf_addf(&sb, "%s/refs", refs->gitdir);
+		if (rmdir(sb.buf) < 0) {
+			strbuf_addf(err, "could not delete refs directory: %s",
+				    strerror(errno));
+			ret = -1;
+		}
+
+		strbuf_release(&sb);
+	}
+
+	return ret;
 }
 
 int repo_resolve_gitlink_ref(struct repository *r,
diff --git a/refs/files-backend.c b/refs/files-backend.c
index b40d6feb1f..9cde3ba724 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -3707,7 +3707,11 @@ static int files_ref_store_remove_on_disk(struct ref_store *ref_store,
 	if (for_each_root_ref(refs, remove_one_root_ref, &data) < 0)
 		ret = -1;
 
-	if (ref_store_remove_on_disk(refs->packed_ref_store, err) < 0)
+	/*
+	 * Directly access the cleanup functions for packed-refs as the generic function
+	 * would try to clear stubs which isn't required for the files backend.
+	 */
+	if (refs->packed_ref_store->be->remove_on_disk(refs->packed_ref_store, err) < 0)
 		ret = -1;
 
 	strbuf_release(&sb);
diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c
index 964b0b50fc..0e220d6bb5 100644
--- a/refs/reftable-backend.c
+++ b/refs/reftable-backend.c
@@ -495,9 +495,6 @@ static int reftable_be_create_on_disk(struct ref_store *ref_store,
 	safe_create_dir(the_repository, sb.buf, 1);
 	strbuf_reset(&sb);
 
-	refs_create_refdir_stubs(the_repository, refs->base.gitdir,
-				 "this repository uses the reftable format");
-
 	strbuf_release(&sb);
 	return 0;
 }
@@ -523,30 +520,6 @@ static int reftable_be_remove_on_disk(struct ref_store *ref_store,
 			    strerror(errno));
 		ret = -1;
 	}
-	strbuf_reset(&sb);
-
-	strbuf_addf(&sb, "%s/HEAD", refs->base.gitdir);
-	if (unlink(sb.buf) < 0) {
-		strbuf_addf(err, "could not delete stub HEAD: %s",
-			    strerror(errno));
-		ret = -1;
-	}
-	strbuf_reset(&sb);
-
-	strbuf_addf(&sb, "%s/refs/heads", refs->base.gitdir);
-	if (unlink(sb.buf) < 0) {
-		strbuf_addf(err, "could not delete stub heads: %s",
-			    strerror(errno));
-		ret = -1;
-	}
-	strbuf_reset(&sb);
-
-	strbuf_addf(&sb, "%s/refs", refs->base.gitdir);
-	if (rmdir(sb.buf) < 0) {
-		strbuf_addf(err, "could not delete refs directory: %s",
-			    strerror(errno));
-		ret = -1;
-	}
 
 	strbuf_release(&sb);
 	return ret;

-- 
2.52.0