Re: [PATCH] Fix start_command closing cmd->out/in regardless of cmd->close_out/in

From: Ping Yin <pkufranky@gmail.com>
Date: Nov 21, 2007, 02:38 UTC
Message-ID: <46dff0320711201838g5affba6bo21a8c837b0bef681@mail.gmail.com>
In-Reply-To: <474308A5.8070301@viscovery.net>

On Nov 21, 2007 12:17 AM, Johannes Sixt <j.sixt@viscovery.net> wrote:

Show 24 quoted lines

> Ping Yin schrieb:
> > This patch disables the auto closing behavious of start_command
> > and corrects all codes which depend on this kind of behaviour.
>
> I've thought about this a bit more, and I think that it is better to leave
> this auto-closing behavior unchanged and change your usage of this feature,
> like so:
>
> > +static void wt_status_print_submodule_summary(struct wt_status *s)
> > +{
> > +       struct child_process sm_summary;
> > +       memset(&sm_summary, 0, sizeof(sm_summary));
> > +       ...
> > +       sm_summary.out = fileno(s->fp);
>
>         fflush(s->fp);
>         sm_summary.out = dup(fileno(s->fp));    /* run_command closes it */
>
> > +       ...
> > +       run_command(&sm_summary);
> > +}
>
> This way the change is more local without affecting well-tested other callers.
>

This way works, but it is a tricky one, not a natural or graceful one.

> Furthermore, I don't think that it's correct to just set the .close_in or
> .close_out flags. This will close the fd only in finish_command(), which can
> be too late: Think again of a writable pipe end that remains open and keeps
> the reader waiting for input that is not going to happen.

This may happen. However, i have scanned all the git codes using the auto closing behaviour and i don't discover the problem you mentioned. So i think it deserves to correct the misbehaviour after carefully testing. And we can make a clarification for that if necessary.

>
> -- Hannes
>
>

-- 
Ping Yin