Re: [PATCH] worktree: avoid dead-code in conditional

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 24, 2020, 21:20 UTC
Message-ID: <xmqqsgek5fg3.fsf@gitster.c.googlers.com>
In-Reply-To: <20200624190541.5253-1-sunshine@sunshineco.com>

Eric Sunshine <sunshine@sunshineco.com> writes:

Show 9 quoted lines

> get_worktrees() retrieves a list of all worktrees associated with a
> repository, including the main worktree. The location of the main
> worktree is determined by get_main_worktree() which needs to handle
> three distinct cases for the main worktree after absolute-path
> conversion:
>
>     * <bare-repository>/.
>     * <main-worktree>/.git/. (when $CWD is .git)
>     * <main-worktree>/.git (when $CWD is any worktree)

It is unclear from the above but I would assume that you are talking about the returned path from get_git_common_dir().

I can certainly understand why there needs two distinct cases (i.e.. bare vs non-bare), but why is this codepath (or any caller of get_git_common_dir()) forced to care about the two cases?

I wonder if the right "fix" to this instance, at the same time preventing similar breakages in the future, is rather make sure get_git_common_dir() not to return the redundant path with ".git/." suffixed? For that matter, I do not know why the bare case must need "/." suffix. There seem to be about a dozen callers of the function, but don't some of them share a similar issue?

Let's look at the other two grep hits from worktree.c

	strbuf_reset(&path);
	strbuf_addf(&path, "%s/worktrees/%s/HEAD", get_git_common_dir(), id);

	worktree = xcalloc(1, sizeof(*worktree));
	worktree->path = strbuf_detach(&worktree_path, NULL);
	worktree->id = xstrdup(id);
	add_head_info(worktree);

done:
	strbuf_release(&path);
	strbuf_release(&worktree_path);
	return worktree;
}

This looks somewhat bogus. "sturct strbuf path" is populated, but is released without ever getting used, isn't it? Am I grossly misreading the code?

The other one

	strbuf_addf(&path, "%s/worktrees", get_git_common_dir());
	dir = opendir(path.buf);
	strbuf_release(&path);
	if (dir) {
		while ((d = readdir(dir)) != NULL) {
		...

is a regular filesystem access, but it ends up opening the directory with a path like "foo/.git/./worktrees", where we should be using a more reasonable "foo/.git/worktrees" to access it. The redundant "/./" is not wrong per-se, but it looks sloppy to depend on "not wrong per-se".

Puzzled.