Re: [PATCH 3/5] worktree: teach "repair" to fix outgoing links to worktrees

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 27, 2020, 17:14 UTC
Message-ID: <xmqqh7soqady.fsf@gitster.c.googlers.com>
In-Reply-To: <20200827082129.56149-4-sunshine@sunshineco.com>

Eric Sunshine <sunshine@sunshineco.com> writes:

Show 18 quoted lines

> The .git/worktrees/<id>/gitdir file points at the location of a linked
> worktree's .git file. Its content must be of the form
> /path/to/worktree/.git (from which the location of the worktree itself
> can be derived by stripping the "/.git" suffix). If the gitdir file is
> deleted or becomes corrupted or outdated, then Git will be unable to
> find the linked worktree. An easy way for the gitdir file to become
> outdated is for the user to move the worktree manually (without using
> "git worktree move"). Although it is possible to manually update the
> gitdir file to reflect the new linked worktree location, doing so
> requires a level of knowledge about worktree internals beyond what a
> user should be expected to know offhand.
>
> Therefore, teach "git worktree repair" how to repair broken or outdated
> .git/worktrees/<id>/gitdir files automatically. (For this to work, the
> command must either be invoked from within the worktree whose gitdir
> file requires repair, or from within the main or any linked worktree by
> providing the path of the broken worktree as an argument to "git
> worktree repair".)

Would git "work" in a corrupt worktree whose gitfile is broken, in the sense that it notices that the cwd is the top of the working tree of a secondary worktree? I can imagine how it would work, starting in one of the functioning worktrees so that git can locate where the primary copy is, with end-user supplied path to a directory that is supposed to be the top of the working tree of a secondary worktree.

Hmph, if the secondary is _moved_, how would "worktree repair $path" would know which <id> the $path corresponds to? Would we just cull all the <id> that do not point at working secondary worktrees and add the $path as if it were a new one by allocating a new <id>, or reusing a randomly chosen <id> that points at a non-existing location?