RE: Bug report - Can create worktrees from bare repo / such worktrees can fool is_bare_repository()

On December 19, 2021 6:30 PM, Eric Sunshine wrote:

On Sun, Dec 19, 2021 at 5:51 PM [off-list ref] wrote:

quoted

On December 19, 2021 5:23 PM, Sean Allred wrote:

quoted

quoted

what about the comparison code where is_bare_repository_cfg is
compared with 1 (it is a boolean and sometimes set to -1). This
would not generally pass a code review.

I'm sorry, I'm afraid I don't completely follow.  Wouldn't the most
straightforward change be to simply follow the documented
recommendation when we create the worktree config in `git sparse-
checkout init`?  Specifically,

    +    if (is_bare_repository())
    +      git_config_set_in_file_gently(config_path, "core.bare", "false");
    +

Are we saying the comparison within is_bare_repository() may not be
appropriate in this case?

I'm suggesting that:

        worktree->is_bare = (is_bare_repository_cfg == 1) ||
                is_bare_repository();

the == 1 comparison should not be done for boolean-style variables. It is an

int, but initialized to -1. Unless -1 and 1 mean different things, but that is not
really documented.

`is_bare_repository_cfg` is not exactly a boolean; it's a tristate, with -1
meaning "not yet determined". I didn't, at the time, closely follow the
discussion[1] of the particular bit of code you're questioning, but the `== 1`
was mentioned at least a couple times, once in review by Junio[2], and then
in the extra patch commentary by "jtan" when he submitted v2[3]. Anyhow,
if I'm following the original discussion correctly, then the usage, `== 1` (or the
equivalent `> 0`) is probably correct, and that treating it as a simple boolean
(where
-1 is true, too) would be undesirable. (Of course, I haven't traced through the
init code at all, so I don't even know if it can ever be
-1 at this point.) Five existing consumers of this global variable use `== 1`, and
only two use `> 0`, so this usage is at least reasonably consistent with other
parts of the project.

[1]: https://lore.kernel.org/git/20190419172128.130170-1-
jonathantanmy@google.com/T/
[2]: https://lore.kernel.org/git/xmqqo954gira.fsf@gitster-ct.c.googlers.com/ (local)
[3]: https://lore.kernel.org/git/20190419172128.130170-1-
jonathantanmy@google.com/

Thanks for the clarification. It helps to understand the code. Could the variable type be changed to a new typedef like ConfigTriState instead of int to be clear about its semantics? Or perhaps an enum with -1, 0, 1 declared explicitly?
-Randall