[PATCH 0/5] diff output_prefix cleanups

From: Jeff King <peff@peff.net>
Date: Oct 3, 2024, 21:05 UTC
Message-ID: <20241003210548.GB11180@coredump.intra.peff.net>
In-Reply-To: <pull.1806.v2.git.1727956724.gitgitgadget@gmail.com>

On Thu, Oct 03, 2024 at 11:58:41AM +0000, Derrick Stolee via GitGitGadget wrote:

Show 14 quoted lines

> This fixes a regression introduced in 2.46.0.
> 
> The change made in 394affd46d (line-log: always allocate the output prefix,
> 2024-06-07) made the method more consistent in that it did not return a
> static empty string that would fail to free(), but it does lead to
> double-frees when a strbuf buffer is freed multiple times.
> 
> In v2, I add Peff's test to the first patch. I also split his diff into two
> more follow-up patches because the additional clarity seems valuable to me.
> I have forged his sign-off in all three patches.
> 
> Note to the maintainer: feel free to take only the first patch, as Peff
> replied that he may work on the remaining cleanup independently (but I had
> already prepared patches 2 & 3).

Oh, I wasn't expecting you to go to that trouble, and had already polished them up myself. :)

So certainly your patch 1 looks good to me now. Here's what I would put on top (but I would suggest making it a separate branch, since yours is a fairly urgent fix and mine is all cleanup).

  [1/5]: line-log: use diff_line_prefix() instead of custom helper
  [2/5]: diff: drop line_prefix_length field
  [3/5]: diff: return const char from output_prefix callback
  [4/5]: diff: return line_prefix directly when possible
  [5/5]: diff: store graph prefix buf in git_graph struct

 diff-lib.c   |  4 ++--
 diff.c       | 10 +++-------
 diff.h       |  3 +--
 graph.c      | 29 +++++++++++++++++------------
 line-log.c   | 14 ++------------
 log-tree.c   |  7 +------
 range-diff.c |  4 ++--
 7 files changed, 28 insertions(+), 43 deletions(-)

-Peff