From owner-freebsd-net  Thu Mar 20  8:30: 1 2003
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Date: Thu, 20 Mar 2003 08:29:54 -0800
From: Luigi Rizzo <rizzo@icir.org>
To: Bruce Evans <bde@zeta.org.au>
Cc: Peter Pentchev <roam@ringlet.net>, net@FreeBSD.ORG,
	Tristan Goode <tgoode@iprimus.com.au>
Subject: Re: write(2) SIGPIPE on a closed socket?
Message-ID: <20030320082954.B15241@xorpc.icir.org>
References: <20030319093002.GT468@straylight.oblivion.bg> <20030319013748.A84035@xorpc.icir.org> <20030319094506.GB27330@straylight.oblivion.bg> <20030319215212.V8375@gamplex.bde.org>
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In-Reply-To: <20030319215212.V8375@gamplex.bde.org>; from bde@zeta.org.au on Wed, Mar 19, 2003 at 10:27:57PM +1100
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On Wed, Mar 19, 2003 at 10:27:57PM +1100, Bruce Evans wrote:
...
<re. SIGPIPE handling>
...
> Similarly in for sockets except in the SO_NOSIGPIPE case, unless I am
> misreading uipc_syscalls.c:sendit():
> 
> % 	error = so->so_proto->pr_usrreqs->pru_sosend(so, to, &auio, 0, control,
> % 						     flags, td);
> % 	if (error) {
> % 		if (auio.uio_resid != len && (error == ERESTART ||
> % 		    error == EINTR || error == EWOULDBLOCK))
> % 			error = 0;
> % 		/* Generation of SIGPIPE can be controlled per socket */
> % 		if (error == EPIPE && !(so->so_options & SO_NOSIGPIPE)) {
> % 			PROC_LOCK(td->td_proc);
> % 			psignal(td->td_proc, SIGPIPE);
>   			^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> % 			PROC_UNLOCK(td->td_proc);
> % 		}
> % 	}
> 
> This code seems to have an interesting version of mishandling short
> i/o counts (auio.uio_resid != len && auio.ui_resid != 0).  Short i/o
> counts involving an interrupt are normally the only ones handled
> correctly (by the ERESTART/EINTR/EWOULDBLOCK fixup).  However, in the
> case of EPIPE/SIGPIPE, we only notice the SIGPIPE after we do the
> fixup, so we never do the fixup and always return an error instead of
> the short i/o count.

this is probably harmless because the pipe is gone anyways,
so it matters little how many bytes have been written, right ?

	cheers
	luigi

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