From owner-freebsd-arch Thu Oct 25 17:39: 4 2001 Delivered-To: freebsd-arch@freebsd.org Received: from elvis.mu.org (elvis.mu.org [216.33.66.196]) by hub.freebsd.org (Postfix) with ESMTP id CB93237B405; Thu, 25 Oct 2001 17:39:02 -0700 (PDT) Received: by elvis.mu.org (Postfix, from userid 1192) id 924C581D05; Thu, 25 Oct 2001 19:38:57 -0500 (CDT) Date: Thu, 25 Oct 2001 19:38:57 -0500 From: Alfred Perlstein To: Robert Watson Cc: arch@FreeBSD.org Subject: Re: Behavior of select() on pipes Message-ID: <20011025193857.U15052@elvis.mu.org> References: <20011025161200.N15052@elvis.mu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from rwatson@FreeBSD.org on Thu, Oct 25, 2001 at 06:14:45PM -0400 Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG * Robert Watson [011025 17:14] wrote: > > On Thu, 25 Oct 2001, Alfred Perlstein wrote: > > > * Robert Watson [011025 14:56] wrote: > > > > > > Alfred recently pointed me at some FreeBSD pipe behavior that I was > > > previously unaware of: select() will always return true regarding the > > > readability of a fifo, regardless of whether data is pending on the fifo. > > > He referred to this as "brokenness", which is a diagnosis I tend to > > > accept. However, it turns out to be somewhat more complicated than I > > > thought, witnessed by the extensive discussion on freebsd-bugs, and logged > > > in PR/19871. But to the short of it: it sounds to me like we should > > > modify the behavior of select() to match the more popular (but possibly > > > standards-incompliant) behavior, which allows select to block on the fifo > > > until data is ready (found in Solaris, Linux, et al). Rather than just > > > commit the patch, I thought I'd open myself up for broad flamage. > > > Comments on what to do are welcome. > > > > If the patch safely brings us into compatibility with both Linux and > > Solaris it's a no-brainer, just put it in, however if it puts FreeBSD > > into some other 'mode' I think it deserves further discussion. > > My understanding, from my reading of the PR, is that it does so. However, > I'm not familiar with the sections of the standards describing fifos, and > was hoping for input from those that would. I'll look at it, I have a couple of non freebsd hosts (blech) to try it on. -- -Alfred Perlstein [alfred@freebsd.org] 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.' http://www.morons.org/rants/gpl-harmful.php3 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message