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From: Jeff King <peff@peff.net>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	Andrei Rybak <rybak.a.v@gmail.com>
Subject: Re: [PATCH v2 1/3] bundle cmd: stop leaking memory from parse_options_cmd_bundle()
Date: Thu, 24 Jun 2021 12:54:24 -0400	[thread overview]
Message-ID: <YNS4wCjkp4yiLLBQ@coredump.intra.peff.net> (raw)
In-Reply-To: <patch-1.3-932c0883ce0-20210621T151357Z-avarab@gmail.com>

On Mon, Jun 21, 2021 at 05:16:12PM +0200, Ævar Arnfjörð Bjarmason wrote:

> Fix a memory leak from the prefix_filename() function introduced with
> its use in 3b754eedd5 (bundle: use prefix_filename with bundle path,
> 2017-03-20).
> 
> As noted in that commit the leak was intentional as a part of being
> sloppy about freeing resources just before we exit, I'm changing this
> because I'll be fixing other memory leaks in the bundle API (including
> the library version) in subsequent commits. It's easier to reason
> about those fixes if valgrind runs cleanly at the end without any
> leaks whatsoever.

Looking at that old commit, it seems like this is a good candidate for
just inserting a single UNLEAK(bundle_file) into cmd_bundle(). But it
looks like the allocation has now migrated into all of the individual
sub-command functions, so we have to deal with it multiple times. They
could still use UNLEAK() if you want to avoid the "ret = foo(); free();
return ret" dance in each one, though.

We should avoid UNLEAK() in library-ish functions, but sub-commands that
are just one step away from cmd_bundle() returning are OK uses, IMHO.

> @@ -92,77 +93,107 @@ static int cmd_bundle_create(int argc, const char **argv, const char *prefix) {
>  	if (progress && all_progress_implied)
>  		strvec_push(&pack_opts, "--all-progress-implied");
>  
> -	if (!startup_info->have_repository)
> +	if (!startup_info->have_repository) {
> +		die_no_repo = 1;
> +		goto cleanup;
> +	}
> +	ret = !!create_bundle(the_repository, bundle_file, argc, argv, &pack_opts, version);
> +cleanup:
> +	free(bundle_file);
> +	if (die_no_repo)
>  		die(_("Need a repository to create a bundle."));
> -	return !!create_bundle(the_repository, bundle_file, argc, argv, &pack_opts, version);
> +	return ret;
>  }

This die_no_repo stuff confused me at first. But I think you are trying
to make sure we call free(bundle_file) before die? There is no point in
spending any effort on that, I think. When we exit() via die(), the
variable is still on the stack, and hence not leaked. And there are
probably a zillion other places we can hit a die() inside
create_bundle() anyway, which would produce the same effect. There's not
much point treating this one specially.

-Peff

  reply	other threads:[~2021-06-24 16:54 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-17 11:21 [PATCH 0/3] bundle.c: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-06-17 11:21 ` [PATCH 1/3] bundle cmd: stop leaking memory from parse_options_cmd_bundle() Ævar Arnfjörð Bjarmason
2021-06-17 11:21 ` [PATCH 2/3] bundle.c: use a temporary variable for OIDs and names Ævar Arnfjörð Bjarmason
2021-06-17 11:21 ` [PATCH 3/3] bundle: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-06-19  2:12   ` Andrei Rybak
2021-06-21 15:16 ` [PATCH v2 0/3] bundle.c: " Ævar Arnfjörð Bjarmason
2021-06-21 15:16   ` [PATCH v2 1/3] bundle cmd: stop leaking memory from parse_options_cmd_bundle() Ævar Arnfjörð Bjarmason
2021-06-24 16:54     ` Jeff King [this message]
2021-06-24 19:28       ` Ævar Arnfjörð Bjarmason
2021-06-21 15:16   ` [PATCH v2 2/3] bundle.c: use a temporary variable for OIDs and names Ævar Arnfjörð Bjarmason
2021-06-21 15:16   ` [PATCH v2 3/3] bundle: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-06-24 17:11     ` Jeff King
2021-06-24 19:31       ` Ævar Arnfjörð Bjarmason
2021-06-29  1:02       ` Junio C Hamano
2021-06-24 17:14   ` [PATCH v2 0/3] bundle.c: " Jeff King
2021-06-30 14:06   ` [PATCH v3 0/3] Ævar Arnfjörð Bjarmason
2021-06-30 14:06     ` [PATCH v3 1/3] bundle cmd: stop leaking memory from parse_options_cmd_bundle() Ævar Arnfjörð Bjarmason
2021-06-30 17:26       ` Jeff King
2021-06-30 18:00         ` Ævar Arnfjörð Bjarmason
2021-07-01 15:41           ` Jeff King
2021-06-30 14:06     ` [PATCH v3 2/3] bundle.c: use a temporary variable for OIDs and names Ævar Arnfjörð Bjarmason
2021-06-30 14:06     ` [PATCH v3 3/3] bundle: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-06-30 21:18       ` Junio C Hamano
2021-06-30 17:34     ` [PATCH v3 0/3] Jeff King
2021-06-30 17:45       ` Jeff King
2021-06-30 18:00         ` Ævar Arnfjörð Bjarmason
2021-07-01 10:53           ` Ævar Arnfjörð Bjarmason
2021-07-02  9:57     ` [PATCH v4 0/3] bundle.c: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-07-02  9:57       ` [PATCH v4 1/3] bundle cmd: stop leaking memory from parse_options_cmd_bundle() Ævar Arnfjörð Bjarmason
2021-07-02  9:57       ` [PATCH v4 2/3] bundle.c: use a temporary variable for OIDs and names Ævar Arnfjörð Bjarmason
2021-07-02  9:57       ` [PATCH v4 3/3] bundle: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-07-03 10:52       ` [PATCH v4 0/3] bundle.c: " Jeff King
2021-07-03 11:28         ` Ævar Arnfjörð Bjarmason

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