Re: [PATCH 09/21] maintenance: add commit-graph task

> On Thu, Jul 09, 2020 at 07:14:41AM -0400, Derrick Stolee wrote:
> 
>> On 7/8/2020 10:29 PM, Jonathan Tan wrote:
>>>> +static int run_write_commit_graph(struct repository *r)
>>>> +{
>>>> +	int result;
>>>> +	struct argv_array cmd = ARGV_ARRAY_INIT;
>>>> +
>>>> +	argv_array_pushl(&cmd, "-C", r->worktree,
>>>> +			 "commit-graph", "write",
>>>> +			 "--split", "--reachable",
>>>> +			 NULL);
>>>
>>> As mentioned in my reply to an earlier patch (sent a few minutes ago),
>>> this won't work if there are environment variables like GIT_DIR present.
>>
>> Do we not pass GIT_DIR to the subcommand? Or does using "-C" override
>> the GIT_DIR?
> 
> We do pass GIT_DIR to the subcommand, and "-C" does not override it. I
> think this code would work as long as "r" is the_repository, which it
> would be in the current code. But then the "-C" would be doing nothing
> useful (it might change to the top of the worktree if we weren't there
> for some reason, but I don't think "commit-graph write" would care
> either way).
> 
> But if "r" is some other repository, "commit-graph" would continue to
> operate in the parent process repository because of the inherited
> GIT_DIR. Using "--git-dir" would solve that, but as a general practice,
> if you're spawning a sub-process that might be in another repository,
> you should clear any repo-specific environment variables. The list is in
> local_repo_env, which you can feed to the "env" or "env_array" parameter
> of a child_process (see the use in connect.c for an example).
> 
> Even in the current scheme where "r" is always the_repository, I suspect
> this might still be buggy. If we're in a bare repository, presumably
> r->worktree would be NULL.