From owner-freebsd-current Tue Dec 24 3:40:32 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id CBA2337B401 for ; Tue, 24 Dec 2002 03:40:30 -0800 (PST) Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.86.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0531343ED8 for ; Tue, 24 Dec 2002 03:40:30 -0800 (PST) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.12.6/8.12.6) with ESMTP id gBOBePu6030918 for ; Tue, 24 Dec 2002 12:40:25 +0100 (CET) (envelope-from phk@critter.freebsd.dk) To: current@freebsd.org Subject: revoke(2) redux... From: Poul-Henning Kamp Date: Tue, 24 Dec 2002 12:40:25 +0100 Message-ID: <30917.1040730025@critter.freebsd.dk> Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG I've been studying revoke(2), and somehow fail to see it fulfill its promise from the man-page. Consider this piece of code from init(8): >/* > * Start a session and allocate a controlling terminal. > * Only called by children of init after forking. > */ >void >setctty(char *name) >{ > int fd; > > (void) revoke(name); > if ((fd = open(name, O_RDWR)) == -1) { > stall("can't open %s: %m", name); > _exit(1); > } Isn't there a pretty obvious race between the revoke() and the open() ? Wouldn't it in fact make much more sense if revoke(2) was defined as int revoke(int fd); /* kick everybody else off */ and the code above would look like: > if ((fd = open(name, O_RDWR)) == -1) { > stall("can't open %s: %m", name); > _exit(1); > } > (void) revoke(fd); -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message