From owner-freebsd-arch@FreeBSD.ORG Tue May 24 02:52:03 2005 Return-Path: X-Original-To: arch@freebsd.org Delivered-To: freebsd-arch@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 284E016A41C; Tue, 24 May 2005 02:52:03 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9D5FB43D1D; Tue, 24 May 2005 02:52:00 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from [192.168.254.14] (imini.samsco.home [192.168.254.14]) (authenticated bits=0) by pooker.samsco.org (8.13.3/8.13.3) with ESMTP id j4O2sRwH025147; Mon, 23 May 2005 20:54:27 -0600 (MDT) (envelope-from scottl@samsco.org) Message-ID: <42929680.3000309@samsco.org> Date: Mon, 23 May 2005 20:50:40 -0600 From: Scott Long User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7.7) Gecko/20050416 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Harti Brandt References: <20050523153118.C28521@beagle.kn.op.dlr.de> In-Reply-To: <20050523153118.C28521@beagle.kn.op.dlr.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.8 required=3.8 tests=ALL_TRUSTED autolearn=failed version=3.0.2 X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on pooker.samsco.org Cc: arch@freebsd.org Subject: Re: Handling of shell builtins in make(1) X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 24 May 2005 02:52:03 -0000 Harti Brandt wrote: > > Hi all, > > I think I found a problem in the shell code in make(1), but I'm not sure > whether to fix it or not and how. The problem is as follows: in compat > mode (this is the default mode when make(1) is not called with -j) the > command lines of a target are executed by one shell per line (this is > also how Posix wants it). To reduce the number of shells make does an > optimisation: when the command line does not contain one of a > pre-defined set of meta characters and does not start with one of a > predefined set of shell builtins, make directly exec's the command > instead of using an intermediate shell. The problem is that the current > list of builtins is limited to: > > alias cd eval exec exit read set ulimit unalias umask unset wait > > Obviously this is not the full set of shell builtins and does also not > contain the shell reserved words. > > The result of this is that for one and the same command you can get > different behaviour whether you execute it via make(1) or via sh -c '...'. > As an example take echo(1). When called via the sh -c you get the builtin > echo which supports the -e option, when executed by make(1) you get > /bin/echo which doesn't. If you suddenly include a shell meta character > in the command line: > > foo: > echo "MAKEFLAGS: ${MAKEFLAGS}" > > you suddenly get also the builtin (':' is a meta character). > > For the reserved words the situation is almost the same. With the > following makefile: > > foo: > if > > one gets: > > if:No such file or directory, while > > foo: > if [ -x /bin/sh ] ; then echo hey ; fi > > you get what you expect. > > I think all this may be very confusing. The question is what to do. I > see the following options: > > 1. leave it as it is. > > 2. include the Posix reserved words and builtins into the list. > > 3. include all reserved words and builtins of our shell into the list. > > Option (3) is probably best. With (2) you still get different behaviour > for the two command lines in: > > foo: > bind -h > bind -h * > > (the first line will try to find bind in the path while the second will > execute the shell builtin). > > Opinions? > > harti 4. Separate /bin/sh into a front end and back end (libsh) and include libsh into make. (running and hiding as I hit the 'send' key) Scott