Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754268AbbLKWat (ORCPT ); Fri, 11 Dec 2015 17:30:49 -0500 Received: from terminus.zytor.com ([198.137.202.10]:51654 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753277AbbLKWas (ORCPT ); Fri, 11 Dec 2015 17:30:48 -0500 Subject: Re: [PATCH] devpts: Sensible /dev/ptmx & force newinstance To: Andy Lutomirski References: <1CB621EF-1647-463B-A144-D611DB150E15@zytor.com> <20151208223135.GA8352@kroah.com> <87oae0h2bo.fsf@x220.int.ebiederm.org> <56677DE3.5040705@zytor.com> <20151209012311.GA11794@kroah.com> <84B136DF-55E4-476A-9CB2-062B15677EE5@zytor.com> <20151209013859.GA12442@kroah.com> <20151209083225.GA30452@1wt.eu> <87wpskyds7.fsf_-_@x220.int.ebiederm.org> <20151211210400.GL20997@ZenIV.linux.org.uk> <87h9jovgf7.fsf@x220.int.ebiederm.org> <566B4931.5080806@zytor.com> <566B4BAA.3030600@zytor.com> Cc: "Eric W. Biederman" , Al Viro , Greg KH , Jiri Slaby , Linus Torvalds , Aurelien Jarno , Florian Weimer , Serge Hallyn , Jann Horn , "security@kernel.org" , "security@ubuntu.com >> security" , security@debian.org, Willy Tarreau , "linux-kernel@vger.kernel.org" From: "H. Peter Anvin" Message-ID: <566B4E5E.2030800@zytor.com> Date: Fri, 11 Dec 2015 14:29:50 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1029 Lines: 35 On 12/11/15 14:24, Andy Lutomirski wrote: > > To do the whole shebang at once: > > ioctl(ptmx_fd, TIOCWHATEVER, fd_to_devpts_mount); > > returns the slave number if fd_to_devpts_mount points to the right > place or an error if not. > > ptsname(fd) logically does: > > fd_to_devpts_mount = open("/dev/pts", O_RDONLY | O_DIRECTORY); > int n = ioctl(fd, TIOCWHATEVER, fd_to_devpts_mount); > close(fd_to_devpts_mount); > if (n < 0) > return some error; > return "/dev/pts/" + n; > > I think that all kinds of variants are possible. > If we're going to invent new names, any reason to not simply have TIOCPTSNAME, since we can find the pts inode from the ptm fd, and then walk the dentry tree (returning error if unreachable)? Or does that open up entirely new issues? -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/