On Fri, Feb 22, 2019 at 12:07 AM Phillip Wood [off-list ref] wrote:

Hi Michal/Duy

On 21/02/2019 13:50, Michal Suchánek wrote:

quoted

On Thu, 21 Feb 2019 17:50:38 +0700
Duy Nguyen [off-list ref] wrote:

quoted

On Tue, Feb 19, 2019 at 12:05 AM Michal Suchanek [off-list ref] wrote:

quoted

When adding wotktrees git can die in get_common_dir_noenv while
examining existing worktrees because the commondir file does not exist.
Rather than testing if the file exists before reading it handle ENOENT.

I don't think we could go around fixing every access to incomplete
worktrees like this. If this is because of racy 'worktree add', then
perhaps a better solution is make it absolutely clear it's not ready
for anybody to access.

For example, we can suffix the worktree directory name with ".lock"
and make sure get_worktrees() ignores entries ending with ".lock".
That should protect other commands while 'worktree add' is still
running. Only when the worktree is complete that 'worktree add' should
rename the directory to lose ".lock" and run external commands like
git-checkout to populate the worktree.

The problem is we don't forbid worktree names ending with ".lock".
Which means that if we start to forbid them now existing worktrees
might become inaccessible.

I think it is also racy as the renaming breaks the use of mkdir erroring
out if the directory already exists.

You mean the part where we see "fred" exists and decide to try the
name "fred1" instead (i.e. patch 1/2)?

I don't think it's the problem if that's the case. We mkdir
"fred.lock" _then_ check if "fred" exists. If it does, remove
fred.lock and move on to fred1.lock. Then we rename fred1.lock to
fred1 and error out if rename fails.
-- 
Duy