From: Jeff King <peff@peff.net>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 6/6] revisions API: don't leak memory on argv elements that need free()-ing
Date: Mon, 18 Jul 2022 11:45:52 -0400 [thread overview]
Message-ID: <YtWAMP0ROFseFs6B@coredump.intra.peff.net> (raw)
In-Reply-To: <220718.86zgh6wiwa.gmgdl@evledraar.gmail.com>
On Mon, Jul 18, 2022 at 05:13:05PM +0200, Ævar Arnfjörð Bjarmason wrote:
> > But if you went just a little further and made the option "rev should
> > own its own argv", then I think you can simplify life for callers even
> > more. They could construct a strvec themselves and then hand it off to
> > the rev_info, to be cleaned up when release_revisions() is called (and
> > of course freeing the "--" when we overwrite it in the interim, as you
> > do here).
> >
> > Then all of the bisect callers from the previous patch could avoid
> > having to deal with the strvec at all. They'd call bisect_rev_setup(),
> > which would internally attach the memory to rev_info.
>
> Yes, I experimented with this, and it's a solid approach.
>
> But it's a much larger change, particularly since we'd also want to
> update the API itself to take take "const" in the appropriate places to
> do it properly.
Hmm. I was thinking that we'd just have rev_info.we_own_our_argv, and
then release it in release_revisions(). But actually, rev_info does not
hold onto the argv at all! It's totally processed in setup_revisions().
And there it either:
- becomes part of prune_data (in which case a copy is made)
- is passed to handle_revisions_opt(), etc, in which case it is parsed
but not held onto (it's possible that some string option holds onto
a pointer, but the only one I found is --filter, which makes a
copy).
- is passed to handle_revision_arg(), but these days
add_rev_cmdline(), etc, make copies. As they must, otherwise --stdin
would be totally buggy.
So I actually wonder if the comment in bisect_rev_setup() is simply
wrong. It was correct in 2011 when I wrote it, but things changed in
df835d3a0c (add_rev_cmdline(): make a copy of the name argument,
2013-05-25), etc.
In that case, we could replace your patch 5 in favor of just calling
strvec_clear() at the end of bisect_rev_setup(). It's possible there's a
case I'm missing that makes this generally not-safe, but in the case of
bisect_rev_setup() there's a very limited set of items in our argv in
the first place. Doing so also passes the test suite with
SANITIZE=address, though again, this is just exercising the very limited
bisect options here.
-Peff
next prev parent reply other threads:[~2022-07-18 15:46 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-13 13:10 [PATCH 0/6] revisions API: fix more memory leaks Ævar Arnfjörð Bjarmason
2022-07-13 13:10 ` [PATCH 1/6] bisect.c: add missing "goto" for release_revisions() Ævar Arnfjörð Bjarmason
2022-07-13 13:10 ` [PATCH 2/6] test-fast-rebase helper: use release_revisions() (again) Ævar Arnfjörð Bjarmason
2022-07-13 13:10 ` [PATCH 3/6] log: make the intent of cmd_show()'s "rev.pending" juggling clearer Ævar Arnfjörð Bjarmason
2022-07-18 14:51 ` Jeff King
2022-07-13 13:10 ` [PATCH 4/6] log: fix common "rev.pending" memory leak in "git show" Ævar Arnfjörð Bjarmason
2022-07-18 14:57 ` Jeff King
2022-07-18 15:08 ` Ævar Arnfjörð Bjarmason
2022-07-13 13:10 ` [PATCH 5/6] bisect.c: partially fix bisect_rev_setup() memory leak Ævar Arnfjörð Bjarmason
2022-07-18 15:05 ` Jeff King
2022-07-13 13:10 ` [PATCH 6/6] revisions API: don't leak memory on argv elements that need free()-ing Ævar Arnfjörð Bjarmason
2022-07-18 15:11 ` Jeff King
2022-07-18 15:13 ` Ævar Arnfjörð Bjarmason
2022-07-18 15:45 ` Jeff King [this message]
2022-07-29 7:07 ` Ævar Arnfjörð Bjarmason
2022-07-29 18:03 ` Jeff King
2022-07-29 18:37 ` Jeff King
2022-07-29 18:52 ` Junio C Hamano
2022-07-29 19:04 ` Jeff King
2022-07-18 15:14 ` [PATCH 0/6] revisions API: fix more memory leaks Jeff King
2022-07-29 8:31 ` [PATCH v2 " Ævar Arnfjörð Bjarmason
2022-07-29 8:31 ` [PATCH v2 1/6] bisect.c: add missing "goto" for release_revisions() Ævar Arnfjörð Bjarmason
2022-07-29 8:31 ` [PATCH v2 2/6] test-fast-rebase helper: use release_revisions() (again) Ævar Arnfjörð Bjarmason
2022-07-30 5:22 ` Eric Sunshine
2022-07-29 8:31 ` [PATCH v2 3/6] log: make the intent of cmd_show()'s "rev.pending" juggling clearer Ævar Arnfjörð Bjarmason
2022-07-29 18:44 ` Junio C Hamano
2022-07-29 8:31 ` [PATCH v2 4/6] log: fix common "rev.pending" memory leak in "git show" Ævar Arnfjörð Bjarmason
2022-07-29 18:55 ` Jeff King
2022-07-29 19:07 ` Jeff King
2022-07-29 18:59 ` Jeff King
2022-07-29 8:31 ` [PATCH v2 5/6] bisect.c: partially fix bisect_rev_setup() memory leak Ævar Arnfjörð Bjarmason
2022-07-29 8:31 ` [PATCH v2 6/6] revisions API: don't leak memory on argv elements that need free()-ing Ævar Arnfjörð Bjarmason
2022-07-29 19:00 ` Jeff King
2022-07-29 19:02 ` [PATCH v2 0/6] revisions API: fix more memory leaks Jeff King
2022-08-02 15:33 ` [PATCH v3 " Ævar Arnfjörð Bjarmason
2022-08-02 15:33 ` [PATCH v3 1/6] bisect.c: add missing "goto" for release_revisions() Ævar Arnfjörð Bjarmason
2022-08-03 17:13 ` Junio C Hamano
2022-08-02 15:33 ` [PATCH v3 2/6] test-fast-rebase helper: use release_revisions() (again) Ævar Arnfjörð Bjarmason
2022-08-02 15:33 ` [PATCH v3 3/6] log: fix a memory leak in "git show <revision>..." Ævar Arnfjörð Bjarmason
2022-08-03 17:27 ` Jeff King
2022-08-03 17:29 ` Jeff King
2022-08-03 17:54 ` Junio C Hamano
2022-08-02 15:33 ` [PATCH v3 4/6] log: refactor "rev.pending" code in cmd_show() Ævar Arnfjörð Bjarmason
2022-08-03 17:32 ` Jeff King
2022-08-03 17:59 ` Junio C Hamano
2022-08-04 7:51 ` Ævar Arnfjörð Bjarmason
2022-08-04 15:59 ` Junio C Hamano
2022-08-05 9:01 ` Ævar Arnfjörð Bjarmason
2022-08-02 15:33 ` [PATCH v3 5/6] bisect.c: partially fix bisect_rev_setup() memory leak Ævar Arnfjörð Bjarmason
2022-08-02 15:33 ` [PATCH v3 6/6] revisions API: don't leak memory on argv elements that need free()-ing Ævar Arnfjörð Bjarmason
2022-08-03 18:30 ` Junio C Hamano
2022-08-03 17:33 ` [PATCH v3 0/6] revisions API: fix more memory leaks Jeff King
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