Re: [RFC/PATCH 0/5] Fix fetch regression with transport helpers

[Duy Nguyen <pclouds@gmail.com>]

On Wed, Jun 5, 2019 at 6:27 PM Jeff King <peff@peff.net> wrote:
>
> On Wed, Jun 05, 2019 at 10:12:12AM +0200, Johannes Schindelin wrote:
>
> > This fails on macOS, in t5601, both in our osx-clang and osx-gcc jobs, as
> > well as in the StaticAnalysis job. For details, see
> > https://dev.azure.com/gitgitgadget/git/_build/results?buildId=10206
>
> Hmm. I'm having a hard time seeing why (and I can't seem to reproduce it
> locally on a case-insensitive HFS+ filesystem under Linux).
>
> In particular, if the problem is here:
>
> > expecting success:
> >       grep X icasefs/warning &&
> >       grep x icasefs/warning &&
> >       test_i18ngrep "the following paths have collided" icasefs/warning
> >
> > ++ grep X icasefs/warning
> > error: last command exited with $?=1
> > not ok 99 - colliding file detection
>
> then that implies it has to do with the checkout phase, which Felipe's
> patch doesn't touch. Later in the log we see the actual file contents
> (I'm confused as to how this gets here; it looks like debugging bits
> that were added after the main script?):
>
>   2019-06-05T07:58:37.7961890Z Cloning into 'bogus'...
>   2019-06-05T07:58:37.7962430Z done.
>   2019-06-05T07:58:37.7963360Z warning: the following paths have collided (e.g. case-sensitive paths
>   2019-06-05T07:58:37.7964300Z on a case-insensitive filesystem) and only one from the same
>   2019-06-05T07:58:37.7964880Z colliding group is in the working tree:
>   2019-06-05T07:58:37.7965290Z
>   2019-06-05T07:58:37.7966250Z   'x'
>
> whereas a succeeding test expects us to mention both 'x' and 'X'.
>
> So we _did_ find the collision, but somehow 'X' was not reported.
> Looking at the code, I'm not even sure how that could happen. Given that
> this process does involve looking at stat data, it makes me wonder if

It does use stat data in mark_colliding_entries() if core.checkStat is
false. I think on MacOS it's actually true.

I vaguely recall seeing just one 'x' once. I think last time I had a
problem with truncating st_ino, but that should be fixed in e66ceca94b
(clone: fix colliding file detection on APFS, 2018-11-20). So no idea
how this happens again.

> there could be some raciness involved. But again, I'm scratching my head
> as to how exactly, and I couldn't reproduce it under load or with some
> carefully inserted sleep() calls.
-- 
Duy