Re: What's cooking in git.git (Nov 2025, #10; Sun, 30)

> On Sun, Nov 30, 2025 at 09:05:07PM -0800, Junio C Hamano wrote:
>
>> * ar/submodule-gitdir-tweak (2025-11-19) 7 commits
>>  - meson/Makefile: allow setting submodule encoding at build time
>>  - submodule: use hashed name for gitdir
>>  - submodule: fix case-folding gitdir filesystem colisions
>>  - submodule: add extension to encode gitdir paths
>>  - submodule: always validate gitdirs inside submodule_name_to_gitdir
>>  - builtin/credential-store: move is_rfc3986_unreserved to url.[ch]
>>  - submodule--helper: use submodule_name_to_gitdir in add_submodule
>> 
>>  Avoid local submodule repository directory paths overlapping with
>>  each other by encoding submodule names before using them as path
>>  components.
>> 
>>  Will merge to 'next'?
>>  source: <20251119211030.2008441-1-adrian.ratiu@collabora.com>
>
> This topic seems to introduce a race in t7450. Running:
>
>   make && (cd t && ./t7450-bad-git-dotfiles.sh --stress-limit=50)
>
> usually fails within 10 or so iterations, whereas without this topic I
> can reliably get through 50 iterations (since it's racy, nothing is for
> sure, but it seems to trigger pretty easily).
>
> The failing test is the parallel one added by 9cf8547320 (clone: prevent
> clashing git dirs when cloning submodule in parallel, 2024-01-28), which
> is making sure we catch nested modules during a parallel checkout. The
> race seems to be in Git itself, and not an artifact of the test (so this
> isn't a race we want to wave away, but probably a real bug, perhaps even
> one with security implications, according to that commit).
>
> Bisection points to 099fe37397 (submodule: always validate gitdirs
> inside submodule_name_to_gitdir, 2025-11-19). Which seems plausible,
> given that it tries to move those same checks from 9cf8547320 around.
>
> It's also possible that the race was always there and this simply makes
> it worse, but I wasn't ever able to trigger it on a pre-099fe37397
> commit.