From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 23 Mar 2022 20:51:22 GMT
Subject: Re: [RFC PATCH] repo-settings: set defaults even when not in a repo
Message-ID: <xmqqtuboqto5.fsf@gitster.g>
In-Reply-To: <1b27e0b115f858a422e0a2891688227be8f3db01.1648055915.git.steadmon@google.com>

Josh Steadmon <steadmon@google.com> writes:

> prepare_repo_settings() initializes a `struct repository` with various
> default config options and settings read from a repository-local config
> file. In 44c7e62 (2021-12-06, repo-settings:prepare_repo_settings only
> in git repos), prepare_repo_settings was changed to issue a BUG() if it
> is called by a process whose CWD is not a Git repository. This approach
> was suggested in [1].
>
> This breaks fuzz-commit-graph, which attempts to parse arbitrary
> fuzzing-engine-provided bytes as a commit graph file.
> commit-graph.c:parse_commit_graph() calls prepare_repo_settings(), but
> since we run the fuzz tests without a valid repository, we are hitting
> the BUG() from 44c7e62 for every test case.

I think the right approach for such a breakage is to ensure it is in
a repository, not to force prepare_repo_settings() to lie.  In the
day-to-day real code paths the end user uses, we do want to catch
mistakes in our code that calls prepare_repo_settings() when we are
not in a repository.