Function repo_migrate_ref_storage_format

refs.c:3330–3521

}

int repo_migrate_ref_storage_format(struct repository *repo,
				    enum ref_storage_format format,
				    unsigned int flags,
				    struct strbuf *errbuf)
{
	struct ref_store *old_refs = NULL, *new_refs = NULL;
	struct refs_for_each_ref_options for_each_ref_opts = {
		.flags = REFS_FOR_EACH_INCLUDE_ROOT_REFS | REFS_FOR_EACH_INCLUDE_BROKEN,
	};
	struct ref_transaction *transaction = NULL;
	struct strbuf new_gitdir = STRBUF_INIT;
	struct migration_data data = {
		.sb = STRBUF_INIT,
		.name = STRBUF_INIT,
		.mail = STRBUF_INIT,
	};
	int did_migrate_refs = 0;
	int ret;

	if (repo->ref_storage_format == format) {
		strbuf_addstr(errbuf, "current and new ref storage format are equal");
		ret = -1;
		goto done;
	}

	old_refs = get_main_ref_store(repo);

	/*
	 * Worktrees complicate the migration because every worktree has a
	 * separate ref storage. While it should be feasible to implement, this
	 * is pushed out to a future iteration.
	 *
	 * TODO: we should really be passing the caller-provided repository to
	 * `has_worktrees()`, but our worktree subsystem doesn't yet support
	 * that.
	 */
	if (has_worktrees()) {
		strbuf_addstr(errbuf, "migrating repositories with worktrees is not supported yet");
		ret = -1;
		goto done;
	}

	/*
	 * The overall logic looks like this:
	 *
	 *   1. Set up a new temporary directory and initialize it with the new
	 *      format. This is where all refs will be migrated into.
	 *
	 *   2. Enumerate all refs and write them into the new ref storage.
	 *      This operation is safe as we do not yet modify the main
	 *      repository.
	 *
	 *   3. Enumerate all reflogs and write them into the new ref storage.
	 *      This operation is safe as we do not yet modify the main
	 *      repository.
	 *
	 *   4. If we're in dry-run mode then we are done and can hand over the
	 *      directory to the caller for inspection. If not, we now start