Function try_update_sparse_directory

builtin/checkout.c:149–191

* Handle a tree object and determine if we need to recurse into the * tree (READ_TREE_RECURSIVE) or skip it (0). */

 * tree (READ_TREE_RECURSIVE) or skip it (0).
 */
static int try_update_sparse_directory(const struct object_id *oid,
				       struct strbuf *base,
				       const char *pathname,
				       int overlay_mode)
{
	struct strbuf dirpath = STRBUF_INIT;
	struct cache_entry *old;
	int pos, result = READ_TREE_RECURSIVE;

	if (!the_repository->index->sparse_index)
		return result;

	strbuf_addbuf(&dirpath, base);
	strbuf_addstr(&dirpath, pathname);
	strbuf_addch(&dirpath, '/');

	pos = index_name_pos_sparse(the_repository->index,
				    dirpath.buf, dirpath.len);
	if (pos < 0)
		goto cleanup;

	old = the_repository->index->cache[pos];
	if (!S_ISSPARSEDIR(old->ce_mode))
		goto cleanup;

	if (oideq(oid, &old->oid)) {
		/* Tree content already matches; no need to descend. */
		result = 0;
	} else if (!overlay_mode) {
		/*
		 * In non-overlay mode (e.g., restore --staged), replace the
		 * sparse directory OID directly since files not present in
		 * the source tree should be removed anyway.
		 */
		oidcpy(&old->oid, oid);
		old->ce_flags |= CE_UPDATE;
		result = 0;
	}

cleanup:
	strbuf_release(&dirpath);
	return result;
}

static int update_some(const struct object_id *oid, struct strbuf *base,
		       const char *pathname, unsigned mode, void *context)