From owner-freebsd-current@FreeBSD.ORG Wed Jun 20 12:59:10 2007 Return-Path: X-Original-To: current@freebsd.org Delivered-To: freebsd-current@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 18E8D16A469 for ; Wed, 20 Jun 2007 12:59:10 +0000 (UTC) (envelope-from Hartmut.Brandt@dlr.de) Received: from smtp-3.dlr.de (smtp-3.dlr.de [195.37.61.187]) by mx1.freebsd.org (Postfix) with ESMTP id A26D413C46A for ; Wed, 20 Jun 2007 12:59:09 +0000 (UTC) (envelope-from Hartmut.Brandt@dlr.de) Received: from knop-beagle.kn.op.dlr.de ([129.247.173.6]) by smtp-3.dlr.de over TLS secured channel with Microsoft SMTPSVC(6.0.3790.1830); Wed, 20 Jun 2007 14:45:52 +0200 Date: Wed, 20 Jun 2007 14:45:53 +0200 (CEST) From: Harti Brandt X-X-Sender: brandt_h@knop-beagle.kn.op.dlr.de To: Daniel Eischen In-Reply-To: Message-ID: <20070620143830.M33081@knop-beagle.kn.op.dlr.de> References: <46765CB9.9020105@incunabulum.net> <4676C30E.7040300@incunabulum.net> <4676C952.5000607@incunabulum.net> <4676D168.3050502@incunabulum.net> <4678529A.3080308@incunabulum.net> <20070620110702.GB929@lizard.fafoe.narf.at> X-OpenPGP-Key: harti@freebsd.org MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 20 Jun 2007 12:45:52.0301 (UTC) FILETIME=[EF9E2DD0:01C7B338] Cc: Stefan Farfeleder , current@freebsd.org Subject: Re: socklen_t (Re: Multicast problems [PATCH]) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Harti Brandt List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 20 Jun 2007 12:59:10 -0000 On Wed, 20 Jun 2007, Daniel Eischen wrote: DE>On Wed, 20 Jun 2007, Stefan Farfeleder wrote: DE> DE>> On Tue, Jun 19, 2007 at 06:36:39PM -0400, Daniel Eischen wrote: DE>> DE>> > POSIX states that: DE>> > DE>> > o The header shall define the type socklen_t, DE>> > which is an integer type of width of at least 32 bits; see DE>> > APPLICATION USAGE. DE>> > DE>> > and goes on to state: DE>> > DE>> > o The header shall define the unsigned integer DE>> > type sa_family_t. DE>> > DE>> > This seems to imply that our socklen_t should not be an unsigned DE>> > integer (uint32_t), but a signed integer. In APPLICATION USAGE, DE>> > POSIX states: DE>> DE>> I don't understand how you come to that conclusion. Why does not DE>> mentioning whether socklen_t is signed or unsigned imply it should be DE>> signed? DE> DE>Because it explicitly says unsigned for sa_family_t and does not DE>say unsigned for socklen_t. To me, "integer" means a C (signed) DE>integer. The fact that older APIs and implementations used "int" DE>might support the argument to use int32_t just for compatibility DE>reasons. As it stands now, portable code has to have some sort DE>of autoconfig to determine whether or not to use socklen_t or int. DE>I don't see how you can do this with #ifdefs unless you know DE>OS version numbers and when socklen_t first got introduced. In standardese stating 'integer type' means any integer type. It does not imply signed or unsignedness. You might look at paragraph 14 of 6.2.5 of the C standard: "The type char, the signed and unsigned integer types, and the enumerated types are collectively called integer types." DE> DE>> > To forestall portability problems, it is recommended that DE>> > applications not use values larger than 23^1 -1 for the DE>> > socklen_t type. DE>> DE>> That just means that those values will wrap to negative values if DE>> socklen_t is a signed integer type. It ensures that the code works whether the type is signed or unsigned. harti