odb: introduce odb_source_new()

We have three different locations where we create a new ODB source.
Deduplicate the logic via a new `odb_source_new()` function.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

odb.c

@@ -141,6 +141,20 @@ static void read_info_alternates(struct object_database *odb,
 				 const char *relative_base,
 				 int depth);
 
+struct odb_source *odb_source_new(struct object_database *odb,
+				  const char *path,
+				  bool local)
+{
+	struct odb_source *source;
+
+	CALLOC_ARRAY(source, 1);
+	source->odb = odb;
+	source->local = local;
+	source->path = xstrdup(path);
+
+	return source;
+}
+
 static struct odb_source *link_alt_odb_entry(struct object_database *odb,
 					     const char *dir,
 					     const char *relative_base,
@@ -178,10 +192,7 @@ static struct odb_source *link_alt_odb_entry(struct object_database *odb,
 	if (!alt_odb_usable(odb, pathbuf.buf, tmp.buf))
 		goto error;
 
-	CALLOC_ARRAY(alternate, 1);
-	alternate->odb = odb;
-	alternate->local = false;
-	alternate->path = strbuf_detach(&pathbuf, NULL);
+	alternate = odb_source_new(odb, pathbuf.buf, false);
 
 	/* add the alternate entry */
 	*odb->sources_tail = alternate;
@@ -341,9 +352,7 @@ struct odb_source *odb_set_temporary_primary_source(struct object_database *odb,
 	 * Make a new primary odb and link the old primary ODB in as an
 	 * alternate
 	 */
-	source = xcalloc(1, sizeof(*source));
-	source->odb = odb;
-	source->path = xstrdup(dir);
+	source = odb_source_new(odb, dir, false);
 
 	/*
 	 * Disable ref updates while a temporary odb is active, since

odb.h

@@ -89,6 +89,10 @@ struct odb_source {
 	char *path;
 };
 
+struct odb_source *odb_source_new(struct object_database *odb,
+				  const char *path,
+				  bool local);
+
 struct packed_git;
 struct packfile_store;
 struct cached_object_entry;

repository.c

@@ -160,20 +160,24 @@ void repo_set_gitdir(struct repository *repo,
 	 * until after xstrdup(root). Then we can free it.
 	 */
 	char *old_gitdir = repo->gitdir;
+	char *objects_path = NULL;
 
 	repo->gitdir = xstrdup(gitfile ? gitfile : root);
 	free(old_gitdir);
 
 	repo_set_commondir(repo, o->commondir);
+	expand_base_dir(&objects_path, o->object_dir,
+			repo->commondir, "objects");
 
 	if (!repo->objects->sources) {
-		CALLOC_ARRAY(repo->objects->sources, 1);
-		repo->objects->sources->odb = repo->objects;
-		repo->objects->sources->local = true;
+		repo->objects->sources = odb_source_new(repo->objects,
+							objects_path, true);
 		repo->objects->sources_tail = &repo->objects->sources->next;
+		free(objects_path);
+	} else {
+		free(repo->objects->sources->path);
+		repo->objects->sources->path = objects_path;
 	}
-	expand_base_dir(&repo->objects->sources->path, o->object_dir,
-			repo->commondir, "objects");
 
 	repo->objects->sources->disable_ref_updates = o->disable_ref_updates;