Re: [PATCH v2] receive-pack: add option to interrupt pre-receive when client exits

From: Jiang Xin <worldhello.net@gmail.com>
To: Robin Jarry <robin.jarry@6wind.com>
Cc: Git List <git@vger.kernel.org>,
	Nicolas Dichtel <nicolas.dichtel@6wind.com>,
	Patryk Obara <patryk.obara@gmail.com>,
	Junio C Hamano <gitster@pobox.com>,
	Jiang Xin <zhiyou.jx@alibaba-inc.com>
Subject: Re: [PATCH v2] receive-pack: add option to interrupt pre-receive when client exits
Date: Thu, 27 Jan 2022 11:21:23 +0800	[thread overview]
Message-ID: <CANYiYbGME-=w4raiwW3w1_gHzVpsvdStz7xVpKqAwx2r_Vezzw@mail.gmail.com> (raw)
In-Reply-To: <20220126214438.3066132-1-robin.jarry@6wind.com>

On Thu, Jan 27, 2022 at 10:03 AM Robin Jarry <robin.jarry@6wind.com> wrote:
> @@ -800,6 +806,19 @@ static void prepare_push_cert_sha1(struct child_process *proc)
>         }
>  }
>
> +static volatile pid_t hook_pid;

Can we use a flag instead of hook_pid to distinguish the source of the
SIGPIPE signal?
1. "pre-receive" hook exits early without consuming stdin.
2. "pre-receive" hook hangs after receiving commands from stdin, until
client quits by receiving a "ctrl-c".

> +static void kill_hook(int signum)
> +{
> +       if (hook_pid != 0) {
> +               kill(hook_pid, signum);
> +               waitpid(hook_pid, NULL, 0);
> +               hook_pid = 0;

Can we let the signal handler in "pre-receive" to do it job? And we
can show some user friendly error message here. E.g.:

    die("broken pipe: seems like the pre-receive hook exits early
without consuming its stdin");

--
Jiang Xin