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From: Junio C Hamano <gitster@pobox.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Jeff King" <peff@peff.net>
Cc: git@vger.kernel.org, Denton Liu <liu.denton@gmail.com>,
	Jeff Hostetler <jeffhost@microsoft.com>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>
Subject: Re: [PATCH v2] trace2: refactor to avoid gcc warning under -O3
Date: Thu, 20 May 2021 09:20:58 +0900	[thread overview]
Message-ID: <xmqqim3ew905.fsf@gitster.g> (raw)
In-Reply-To: <YJrIMbr6VkYGQMfs@coredump.intra.peff.net> (Jeff King's message of "Tue, 11 May 2021 14:08:49 -0400")

Jeff King <peff@peff.net> writes:

> I also wondered briefly why we needed the out-parameter at all, and not
> just letting the caller look at errno. The answer is that we need to
> preserve it across the close() call. The more usual thing in our code
> base _would_ be to use saved_errno, but not have it as an out-parameter.
>
> I.e.:
>
> diff --git a/trace2/tr2_dst.c b/trace2/tr2_dst.c
> index ae052a07fe..bda283e7f4 100644
> --- a/trace2/tr2_dst.c
> +++ b/trace2/tr2_dst.c
> @@ -204,15 +204,16 @@ static int tr2_dst_try_uds_connect(const char *path, int sock_type, int *out_fd)
>  
>  	fd = socket(AF_UNIX, sock_type, 0);
>  	if (fd == -1)
> -		return errno;
> +		return -1;
>  
>  	sa.sun_family = AF_UNIX;
>  	strlcpy(sa.sun_path, path, sizeof(sa.sun_path));
>  
>  	if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
> -		int e = errno;
> +		int saved_errno = errno;
>  		close(fd);
> -		return e;
> +		errno = saved_errno;
> +		return -1;
>  	}
>  
> ...
>
> I do prefer that approach, since I think it's more idiomatic for our
> code base, but for the sake of wrapping up this simple fix which has
> been discussed much more than I think it deserves, I am OK with either.
> :)

I think this alternative is more readable as well.

I'll mark the topic to be "Expecting a reroll" in the what's cooking
report.

Thanks.

  parent reply	other threads:[~2021-05-20  0:21 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-01  7:30 [PATCH] Fix -Wmaybe-uninitialized warnings under -O0 Denton Liu
     [not found] ` <CAPUEspgBkmxszgBee8C9hZnEwqztf-XKEj7LB_jWVFJaJCge0w@mail.gmail.com>
2020-04-01  9:05   ` Denton Liu
2020-04-01  9:52 ` Jeff King
2020-04-01 14:06   ` Denton Liu
2020-04-03 14:04     ` Jeff King
2020-04-03 14:38       ` Jeff King
2020-04-04 12:07       ` Denton Liu
2020-04-04 14:21         ` Jeff King
2021-05-05  8:40           ` [PATCH] trace2: refactor to avoid gcc warning under -O3 Ævar Arnfjörð Bjarmason
2021-05-05  9:47             ` Junio C Hamano
2021-05-05 13:34               ` Jeff King
2021-05-05 14:38             ` Johannes Schindelin
2021-05-06  1:26               ` Junio C Hamano
2021-05-06 20:29                 ` Johannes Schindelin
2021-05-06 21:10                   ` Junio C Hamano
2021-05-11 14:34                     ` Johannes Schindelin
2021-05-11 18:00                       ` Jeff King
2021-05-11 20:58                         ` Junio C Hamano
2021-05-11 21:07                           ` Jeff King
2021-05-11 21:33                             ` Junio C Hamano
2021-05-11  7:03             ` Junio C Hamano
2021-05-11 13:04             ` [PATCH v2] " Ævar Arnfjörð Bjarmason
2021-05-11 16:40               ` Jeff Hostetler
2021-05-11 17:54               ` Jeff King
2021-05-11 18:08                 ` Jeff King
2021-05-11 21:09                   ` Junio C Hamano
2021-05-20  0:20                   ` Junio C Hamano [this message]
2021-05-20 11:05                     ` [PATCH v3] " Ævar Arnfjörð Bjarmason
2021-05-20 13:13                       ` Jeff King
2021-05-20 22:08                         ` Junio C Hamano
2021-05-21  9:34                           ` Jeff King

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