Re: [PATCH v3] setup: trace bare repository setups

> From: Glen Choo <chooglen@google.com>
>
> safe.bareRepository=explicit is a safer default mode of operation, since
> it guards against the embedded bare repository attack [1]. Most end
> users don't use bare repositories directly, so they should be able to
> set safe.bareRepository=explicit, with the expectation that they can
> reenable bare repositories by specifying GIT_DIR or --git-dir.
>
> However, the user might use a tool that invokes Git on bare repositories
> without setting GIT_DIR (e.g. "go mod" will clone bare repositories
> [2]), so even if a user wanted to use safe.bareRepository=explicit, it
> wouldn't be feasible until their tools learned to set GIT_DIR.
>
> To make this transition easier, add a trace message to note when we
> attempt to set up a bare repository without setting GIT_DIR. This allows
> users and tool developers to audit which of their tools are problematic
> and report/fix the issue.  When they are sufficiently confident, they
> would switch over to "safe.bareRepository=explicit".
>
> Note that this uses trace2_data_string(), which isn't supported by the
> "normal" GIT_TRACE2 target, only _EVENT or _PERF.
>
> [1] https://lore.kernel.org/git/kl6lsfqpygsj.fsf@chooglen-macbookpro.roam.corp.google.com/
> [2] https://go.dev/ref/mod
>
> Signed-off-by: Glen Choo <chooglen@google.com>
> Signed-off-by: Josh Steadmon <steadmon@google.com>
> ---
> I'm sending a lightly-adapted version of Glen's tracing patch because
> Glen will be on vacation next week and we'd like to get this upstream
> ASAP.
>
> Changes in V3: added a test_unconfig test case for safe.bareRepository
> Changes in V2: cleaned up test-style issues.