Re: [PATCH 2/2] grep.c: tolerate NULL grep_expr in free_pattern_expr()

From: Taylor Blau <me@ttaylorr.com>
Date: Oct 10, 2022, 18:14 UTC
Message-ID: <Y0Rg9My2EaWl/WCU@nand.local>
In-Reply-To: <xmqqsfjv35xi.fsf@gitster.g>

On Mon, Oct 10, 2022 at 11:11:05AM -0700, Junio C Hamano wrote:

Show 5 quoted lines

> Junio C Hamano <gitster@pobox.com> writes:
>
> So I think the right thing to do may be to allow free_pattern_expr()
> to take and ignore NULL silently?  Ah, that is already what you are
> doing in the first hunk.  Is this second hunk even necessary?

Right. The fix in my patch is to have `free_pattern_expr()` treat its arguments like `free()` does, where NULL is a silent noop.

We could do with or without the second hunk. I dropped it to avoid confusion, but it seems to have had the opposite effect ;-). I'll keep the if-statement there and instead drop the latter hunk.

> I wonder how calls to grep.c::match_line() with opt->extended true
> and opt->pattern_expression NULL, though.  It should die() at the
> beginning of match_expr_eval(), which probably is OK, but somehow
> feels unsatisfactory.

It does, and we can thank Linus for that: c922b01f54 (grep: fix segfault when "git grep '('" is given, 2009-04-27).

Thanks, Taylor