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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Sat, 17 Nov 2018 11:29:37 +0200
Message-ID: <CABBYNZK1fydodkrSoZAeja-6h50xBBkMLLMNqxFbxsaGCtquiA@mail.gmail.com>
Subject: Re: [PATCH BlueZ] core: Ignore SIGPIPE
To:     Gal Ben Haim <gbenhaim@augury.com>
Cc:     Marcel Holtmann <marcel@holtmann.org>,
        "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
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Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Gal,

Weird I thought send/sendmsg works with pipes, anyway I think we can
apply the handling of SIGPIPE with signalfd then.
On Sat, Nov 17, 2018 at 1:47 AM Gal Ben Haim <gbenhaim@augury.com> wrote:
>
> I tried MSG_NOSIGNAL, see my other patch. the error is io_send: Socket
> operation on non-socket.
>
> please suggest an acceptable solution for this issue
> On Fri, Nov 16, 2018 at 10:11 PM Gal Ben Haim <gbenhaim@augury.com> wrote:
> >
> > 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
> > >


-- 
Luiz Augusto von Dentz