From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: Stefan Beller <sbeller@google.com>,
Johannes.Schindelin@gmx.de, git@vger.kernel.org
Subject: Re: [PATCH 2/2] sequencer.c: plug mem leak in git_sequencer_config
Date: Mon, 04 Jun 2018 13:26:57 +0900 [thread overview]
Message-ID: <xmqqin6z5g8e.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <20180604035637.GA15408@sigill.intra.peff.net> (Jeff King's message of "Sun, 3 Jun 2018 23:56:37 -0400")
Jeff King <peff@peff.net> writes:
> I've looked into it before, but that causes its own wave of headaches.
> The source of the problem is that we do:
>
> const char *some_var = "default";
> ...
> git_config_string(&some_var, ...);
Yup, that is a valid pattern for "run once and let exit(3) clean
after us" programs.
> Doing it "right" in C would probably involve two variables:
>
> const char *some_var = "default";
> const char *some_var_storage = NULL;
>
> int git_config_string_smart(const char **ptr, char **storage,
> const char *var, const char *value)
> {
> ...
> free(*storage);
> *ptr = *storage = xstrdup(value);
> return 0;
> }
>
> #define GIT_CONFIG_STRING(name, var, value) \
> git_config_string_smart(&(name), &(name##_storage), var, value)
>
> Or something like that.
The attitude the approach takes is that "run once and let exit(3)
clean after us" programs *should* care. And at that point, maybe
char *some_var = xstrdup("default");
git_config_string(&some_var, ...);
that takes "char **" and frees the current storage before assigning
to it may be simpler than the two-variable approach.
But you're right. We cannot just unconst the type and be done with
it---there are associated clean-up necessary if we were to do this.
Thanks.
next prev parent reply other threads:[~2018-06-04 4:27 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-01 20:01 [PATCH 1/2] sequencer.c: plug leaks in do_pick_commit Stefan Beller
2018-06-01 20:01 ` [PATCH 2/2] sequencer.c: plug mem leak in git_sequencer_config Stefan Beller
2018-06-04 2:41 ` Junio C Hamano
2018-06-04 3:44 ` Junio C Hamano
2018-06-04 3:56 ` Jeff King
2018-06-04 4:26 ` Junio C Hamano [this message]
2018-06-04 4:51 ` Jeff King
2018-06-04 4:55 ` Junio C Hamano
2018-06-21 7:03 ` Johannes Schindelin
2018-06-21 11:46 ` Jeff King
2018-06-04 5:00 ` Jeff King
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