DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E9312087A
MIME-Version: 1.0
References: <20181116191452.17377-1-gbenhaim@augury.com> <5F365876-5DA6-4916-B810-E2DF1ABD3772@holtmann.org>
In-Reply-To: <5F365876-5DA6-4916-B810-E2DF1ABD3772@holtmann.org>
From:   Gal Ben Haim <gbenhaim@augury.com>
Date:   Fri, 16 Nov 2018 22:11:57 +0200
Message-ID: <CAHotPr-cE2gc9Gue9ekyqgb4fFCR+jPWuVYcQzNrpFc-BmW7-g@mail.gmail.com>
Subject: Re: [PATCH BlueZ] core: Ignore SIGPIPE
To:     Marcel Holtmann <marcel@holtmann.org>
Cc:     linux-bluetooth@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

what should signal_handler do in case of SIGPIPE? will failed write
return EPIPE if the signal is catched?

On Fri, Nov 16, 2018 at 10:01 PM Marcel Holtmann <marcel@holtmann.org> wrote:
>
> Hi Gal,
>
> > bluetoothd receives a SIGPIPE and terminates if writing to a pipe that
> > was acquired by AcquireNotify and there are no readers. it can be
> > reproduced by terminating the reader process without closing the reader
> > end of the pipe.
> >
> > Ignoring the SIGPIPE will cause the write operation to return an
> > error which will be logged as "io_send: Broken pipe".
> > ---
> > src/main.c | 10 +++++++---
> > 1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/src/main.c b/src/main.c
> > index 4716f5388..c62886593 100644
> > --- a/src/main.c
> > +++ b/src/main.c
> > @@ -691,7 +691,7 @@ int main(int argc, char *argv[])
> >       uint16_t sdp_mtu = 0;
> >       uint32_t sdp_flags = 0;
> >       int gdbus_flags = 0;
> > -     guint signal, watchdog;
> > +     guint signal_source, watchdog;
> >       const char *watchdog_usec;
> >
> >       init_defaults();
> > @@ -721,7 +721,11 @@ int main(int argc, char *argv[])
> >
> >       event_loop = g_main_loop_new(NULL, FALSE);
> >
> > -     signal = setup_signalfd();
> > +     signal_source = setup_signalfd();
> > +
> > +     /* Ignore SIGPIPE, a broken pipe error will be returned from write
> > +      * attempts to a pipe with no readers */
> > +     signal(SIGPIPE, SIG_IGN);
>
> if we decide not to use MSG_NOSIGNAL, then everything has to go via signalfd and not just by hacking in signal(SIG_IGN).
>
> Regards
>
> Marcel
>