[PATCH v3 0/2] Properly peel tags in can_all_from_reach_with_flags()

From: "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: peff@peff.net, Junio C Hamano <gitster@pobox.com>
Subject: [PATCH v3 0/2] Properly peel tags in can_all_from_reach_with_flags()
Date: Fri, 21 Sep 2018 08:05:24 -0700 (PDT)	[thread overview]
Message-ID: <pull.39.v3.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.39.v2.git.gitgitgadget@gmail.com>

As Peff reported [1], the refactored can_all_from_reach_with_flags() method
does not properly peel tags. Since the helper method can_all_from_reach()
and code in t/helper/test-reach.c all peel tags before getting to this
method, it is not super-simple to create a test that demonstrates this.

I modified t/helper/test-reach.c to allow calling
can_all_from_reach_with_flags() directly, and added a test in
t6600-test-reach.sh that demonstrates the segfault without the fix.

For V2, I compared the loop that inspects the 'from' commits in commit
ba3ca1edce "commit-reach: move can_all_from_reach_with_flags" to the version
here and got the following diff:

3c3
<                 if (from_one->flags & assign_flag)
---
>                 if (!from_one || from_one->flags & assign_flag)
5c5,7
<                 from_one = deref_tag(the_repository, from_one, "a from object", 0);
---
>
>                 from_one = deref_tag(the_repository, from_one,
>                                      "a from object", 0);
14a17,22
>
>                 list[nr_commits] = (struct commit *)from_one;
>                 if (parse_commit(list[nr_commits]) ||
>                     list[nr_commits]->generation < min_generation)
>                         return 0; /* is this a leak? */
>                 nr_commits++;

This diff includes the early termination we had before 'deref_tag' and the
comment for why we can ignore non-commit objects.

[1] 
https://public-inbox.org/git/0bf9103c-9377-506b-7ad7-e5273d8e94fc@gmail.com/T/#u

Derrick Stolee (2):
  commit-reach: properly peel tags
  commit-reach: fix memory and flag leaks

 commit-reach.c        | 41 ++++++++++++++++++++++++++++++++++-------
 t/helper/test-reach.c | 22 +++++++++++++++++-----
 t/t6600-test-reach.sh | 30 ++++++++++++++++++++++++++++--
 3 files changed, 79 insertions(+), 14 deletions(-)

base-commit: 6621c838743812aaba96e55cfec8524ea1144c2d
Published-As: https://github.com/gitgitgadget/git/releases/tags/pr-39%2Fderrickstolee%2Ftag-fix-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-39/derrickstolee/tag-fix-v3
Pull-Request: https://github.com/gitgitgadget/git/pull/39

Range-diff vs v2:

 1:  4bf21204dd ! 1:  0a1e661271 commit-reach: properly peel tags
     @@ -53,8 +53,11 @@
      +
      +		list[nr_commits] = (struct commit *)from_one;
      +		if (parse_commit(list[nr_commits]) ||
     -+		    list[nr_commits]->generation < min_generation)
     -+			return 0; /* is this a leak? */
     ++		    list[nr_commits]->generation < min_generation) {
     ++			result = 0;
     ++			goto cleanup;
     ++		}
     ++
      +		nr_commits++;
       	}

 -:  ---------- > 2:  b2e0ee4978 commit-reach: fix memory and flag leaks

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