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Date: Sat, 8 Oct 2011 14:31:08 +0200
From: Jilles Tjoelker <jilles@stack.nl>
To: Artem Belevich <art@freebsd.org>
Message-ID: <20111008123108.GA44476@stack.nl>
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Cc: Michael Bushkov <bushman@freebsd.org>, Dag-Erling Sm?rgrav <des@des.no>,
	hackers@freebsd.org, Trond Endrest?l <Trond.Endrestol@fagskolen.gjovik.no>
Subject: Re: Does anyone use nscd?
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On Wed, Oct 05, 2011 at 03:54:00PM -0700, Artem Belevich wrote:
> 2011/10/5 Dag-Erling Sm?rgrav <des@des.no>:
> > Michael Bushkov <bushman@freebsd.org> writes:
> >> 2. Consequences of the aforementioned problem can probably be
> >> corrected by using _setsockopt(..., SO_NOSIGPIPE) in
> >> __open_cached_connection() in nscachedcli.c

> > That sounds like a workaround rather than a fix...

> Not necessarily. Using SO_NOSIGPIPE is a valid option when someone
> wants to see read/write on a closed socket fail and return -1 with
> errno=EPIPE.

> Quick grep in libc shows that resolver code in
> lib/libc/resolv/res_send.c also sets SO_NOSIGPIPE for exactly that
> reason.

Disabling SIGPIPE is good anyway because a crashing/dying nscd should
not cause applications to terminate. However, if EPIPE/SIGPIPE happens
in normal operation, that is still a bug that should be fixed.

By the way, SO_NOSIGPIPE is not in POSIX.1-2008 while the MSG_NOSIGNAL
flag to send() is. It may be better to replace the write() call with
send() with the MSG_NOSIGNAL flag and drop the setsockopt().

-- 
Jilles Tjoelker