Hi Michal/Duy
On 21/02/2019 13:50, Michal Suchánek wrote:
On Thu, 21 Feb 2019 17:50:38 +0700
Duy Nguyen <pclouds@xxxxxxxxx> wrote:
On Tue, Feb 19, 2019 at 12:05 AM Michal Suchanek <msuchanek@xxxxxxx> wrote:
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. One solution is to have a lock
entry in $GIT_COMMON_DIR/worktree-locks and make sure the code that
iterates over the entries in $GIT_COMMON_DIR/worktrees skips any that
have a corresponding ignores in $GIT_COMMON_DIR/worktree-locks. If the
worktree-locks/<dir> is created before worktree/<dir> then it should be
race free (you will have to remove the lock if the real entry cannot be
created and then increment the counter and try again). Entries could
also be locked on removal to prevent a race there.
Best Wishes
Phillip
Thanks
Michal
