Re: [PATCH 6/6] apply: refactor `struct image` to use a `struct strbuf`

From: Junio C Hamano <gitster@pobox.com>
Date: Sep 16, 2024, 19:30 UTC
Message-ID: <xmqq8qvrmm5e.fsf@gitster.g>
In-Reply-To: <6cf45daf84af68f74d87a5b2ae7102d4cd8ceb57.1726470385.git.ps@pks.im>

Patrick Steinhardt <ps@pks.im> writes:

Show 6 quoted lines

> Refactor the code to use a `struct strbuf` instead, addressing all of
> the above. Like this we can easily perform in-place updates in all
> situations, the logic to perform those updates becomes way simpler and
> the lifetime of the buffer becomes a ton easier to track.
>
> This refactoring also plugs some leaking buffers as a side effect.

Nice.

In short, the leaks were in the original code where it was making direct assignment to image->buf, and we now use strbuf_attach(), which releases the current buffer before replacing it with a piece of memory allocated outside the control of strbuf API?

Show 5 quoted lines

>  static void image_remove_last_line(struct image *img)
>  {
> -	img->len -= img->line[--img->line_nr].len;
> +	strbuf_setlen(&img->buf, img->buf.len - img->line[--img->line_nr].len);
>  }

I feel that this, while technically is faithful to the original, got a bit too complex to understand what is going on. Perhaps split it into two statements with an intermediate variable? I dunno.

Thanks.