Re: [RFC PATCH v2 1/4] tag: use a "goto cleanup" pattern, leak less memory

From: Junio C Hamano <gitster@pobox.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, Jeff King <peff@peff.net>
Subject: Re: [RFC PATCH v2 1/4] tag: use a "goto cleanup" pattern, leak less memory
Date: Wed, 20 Oct 2021 07:37:03 -0700	[thread overview]
Message-ID: <xmqqwnm7rcds.fsf@gitster.g> (raw)
In-Reply-To: <RFC-patch-v2-1.4-fc776c3f1cd-20211020T131627Z-avarab@gmail.com> (=?utf-8?B?IsOGdmFyIEFybmZqw7Zyw7A=?= Bjarmason"'s message of "Wed, 20 Oct 2021 15:24:33 +0200")

Ævar Arnfjörð Bjarmason  <avarab@gmail.com> writes:

> Change cmd_tag() to free its "struct string_list"'s instead of using

string_list -> strbuf

> an UNLEAK() pattern. This changes code added in 886e1084d78 (builtin/:
> add UNLEAKs, 2017-10-01).
>
> As shown in the context of the deceleration of the "struct

deceleration?

> msg_arg" (which I'm changing to use a designated initializer while at
> it, and to show the context in this change), that struct is just a
> thin wrapper around an int and "struct strbuf".
>
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> ---
>  builtin/tag.c | 28 ++++++++++++++++------------
>  1 file changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/builtin/tag.c b/builtin/tag.c
> index 6535ed27ee9..ad6c9855914 100644
> --- a/builtin/tag.c
> +++ b/builtin/tag.c
> @@ -432,7 +432,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
>  	int annotate = 0, force = 0;
>  	int cmdmode = 0, create_tag_object = 0;
>  	const char *msgfile = NULL, *keyid = NULL;
> -	struct msg_arg msg = { 0, STRBUF_INIT };
> +	struct msg_arg msg = { .buf = STRBUF_INIT };
>  	struct ref_transaction *transaction;
>  	struct strbuf err = STRBUF_INIT;
>  	struct ref_filter filter;
> @@ -482,6 +482,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
>  		OPT_BOOL('i', "ignore-case", &icase, N_("sorting and filtering are case insensitive")),
>  		OPT_END()
>  	};
> +	int ret = 0;
>  
>  	setup_ref_filter_porcelain_msg();
>  
> @@ -529,7 +530,6 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
>  	ref_sorting_set_sort_flags_all(sorting, REF_SORTING_ICASE, icase);
>  	filter.ignore_case = icase;
>  	if (cmdmode == 'l') {
> -		int ret;
>  		if (column_active(colopts)) {
>  			struct column_options copts;
>  			memset(&copts, 0, sizeof(copts));
> @@ -540,7 +540,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
>  		ret = list_tags(&filter, sorting, &format);
>  		if (column_active(colopts))
>  			stop_column_filter();
> -		return ret;
> +		goto cleanup;
>  	}
>  	if (filter.lines != -1)
>  		die(_("-n option is only allowed in list mode"));
> @@ -552,12 +552,15 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
>  		die(_("--points-at option is only allowed in list mode"));
>  	if (filter.reachable_from || filter.unreachable_from)
>  		die(_("--merged and --no-merged options are only allowed in list mode"));
> -	if (cmdmode == 'd')
> -		return delete_tags(argv);
> +	if (cmdmode == 'd') {
> +		ret = delete_tags(argv);
> +		goto cleanup;
> +	}
>  	if (cmdmode == 'v') {
>  		if (format.format && verify_ref_format(&format))
>  			usage_with_options(git_tag_usage, options);
> -		return for_each_tag_name(argv, verify_tag, &format);
> +		ret = for_each_tag_name(argv, verify_tag, &format);
> +		goto cleanup;
>  	}
>  
>  	if (msg.given || msgfile) {
> @@ -626,10 +629,11 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
>  		printf(_("Updated tag '%s' (was %s)\n"), tag,
>  		       find_unique_abbrev(&prev, DEFAULT_ABBREV));
>  
> -	UNLEAK(buf);
> -	UNLEAK(ref);
> -	UNLEAK(reflog_msg);
> -	UNLEAK(msg);
> -	UNLEAK(err);
> -	return 0;
> +cleanup:
> +	strbuf_release(&buf);
> +	strbuf_release(&ref);
> +	strbuf_release(&reflog_msg);
> +	strbuf_release(&msg.buf);
> +	strbuf_release(&err);
> +	return ret;
>  }