Re: [PATCH v7 4/4] cat-file: add --batch-command mode

[Eric Sunshine <sunshine@sunshineco.com>]

On Tue, Feb 15, 2022 at 10:00 PM Junio C Hamano <gitster@pobox.com> wrote:
> John Cai <johncai86@gmail.com> writes:
> > Yeah, this is what I had before but there was discussion about
> > separation of concerns in [1]. But perhaps it's preferable
> > compared to passing a pointer to nr.
>
> Oh, I see.
>
> I do not see any issue with separation of concerns here, actually.
>
> As long as "dispatch_calls() consumes all the cmd[] before it
> returns to the caller" is clearly understood between the function
> and its caller(s) [*], clearing of "nr" the caller has is entirely
> caller's problem.  It becomes needed only because this caller
> decides to reuse cmd[] array.
>
>         Side note: you do have a comment before the function to tell
>         what to expect out of the helper for its callers, right?

True, it is the caller's problem due to reusing the array, though
dispatch_calls() freeing `line` muddies things slightly. A comment
before the function could indeed be helpful, especially letting
callers know that `line` is being freed.

It probably also would be wise to replace the free() call with
FREE_AND_NULL() in order to address the dangling-pointer concern.