From owner-freebsd-bugs  Sat Oct 13 12: 0:21 2001
Delivered-To: freebsd-bugs@hub.freebsd.org
Received: from freefall.freebsd.org (freefall.FreeBSD.org [216.136.204.21])
	by hub.freebsd.org (Postfix) with ESMTP id 5D1CD37B411
	for <freebsd-bugs@hub.freebsd.org>; Sat, 13 Oct 2001 12:00:06 -0700 (PDT)
Received: (from gnats@localhost)
	by freefall.freebsd.org (8.11.4/8.11.4) id f9DJ06K91607;
	Sat, 13 Oct 2001 12:00:06 -0700 (PDT)
	(envelope-from gnats)
Received: from milliways.chance.ru (milliways.chance.ru [195.190.107.35])
	by hub.freebsd.org (Postfix) with ESMTP id 9A95837B401
	for <FreeBSD-gnats-submit@freebsd.org>; Sat, 13 Oct 2001 11:55:53 -0700 (PDT)
Received: from do-labs.spb.ru (ppp-4.chance.ru [195.190.107.7])
	by milliways.chance.ru (8.9.0/8.9.0) with SMTP id WAA04128
	for <FreeBSD-gnats-submit@freebsd.org>; Sat, 13 Oct 2001 22:55:45 +0400 (MSD)
Received: (qmail 7153 invoked by uid 0); 13 Oct 2001 22:56:59 -0000
Message-Id: <20011013225659.7152.qmail@do-labs.spb.ru>
Date: 13 Oct 2001 22:56:59 -0000
From: root@do-labs.spb.ru
Reply-To: root@do-labs.spb.ru
To: FreeBSD-gnats-submit@freebsd.org
X-Send-Pr-Version: 3.113
Subject: kern/31255: select with zero timeout returns 0 even when data pending
Sender: owner-freebsd-bugs@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-bugs.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-bugs>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-bugs>
X-Loop: FreeBSD.org


>Number:         31255
>Category:       kern
>Synopsis:       select with zero timeout returns 0 even when data pending
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Oct 13 12:00:06 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     dozen@osw.com.ru
>Release:        FreeBSD 4.3-RELEASE-p20 i386
>Organization:
>Environment:
System: FreeBSD eix.do-labs.spb.ru 4.3-RELEASE-p20 FreeBSD 4.3-RELEASE-p20 #1: Fri Oct 12 22:18:27 GMT 2001 root@eix.do-labs.spb.ru:/usr/src/sys/compile/EIX i386


	
>Description:
        struct timeval tv = { 0,0 };
        rc = select(...,&tv);

        This code will always return zero even if data is pending
        one any descriptor or any descriptor is ready to write.
        This is because check for timed out performed before 
        asking kernel about descriptor state.

	Single Unix Spec do not states exactly that zero timeout shall
        lead to immediate return with correct descriptor number as result,
        but it looks like it is supposed to be as such.

>How-To-Repeat:
	
>Fix:
        The problem code is in /usr/src/sys/kern/sys_generic.c

>Release-Note:
>Audit-Trail:
>Unformatted:

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-bugs" in the body of the message