From owner-svn-src-head@freebsd.org Mon Jan 22 18:42:12 2018 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id D250AECF1F6; Mon, 22 Jan 2018 18:42:12 +0000 (UTC) (envelope-from byond.lenox@gmail.com) Received: from mail-io0-f177.google.com (mail-io0-f177.google.com [209.85.223.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 0C0F36805C; Mon, 22 Jan 2018 18:42:10 +0000 (UTC) (envelope-from byond.lenox@gmail.com) Received: by mail-io0-f177.google.com with SMTP id l17so10478555ioc.3; Mon, 22 Jan 2018 10:42:10 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=tGX1vRMYT/o4Hqf8hBePcSGUxfKKAvns0qCSpD2X/eo=; b=YzP2Rqsis/TLBnXV8WeIca4VNaxO8+2pGtskCSLvm+q9a/iX+BERvQ7m77NtM+L1+W L0liPEqcmWXsHNnR14hctVd8Zn82m4SYtEYE32hbBG5vGmfCcVN5LH+Gh7/41qu6qWjK Ldh2X76rPePYoo8MocuJ4wr7ZtqbEdhIkgq++IzIXH/eao3E4kSgxbDnhJzqlijyecXu u6bHk2vn5AjxSyfXQk0TlilKPueIafQ/FCbp2NW+up4h3LmNQmNeYo6svmBK6zdy8cJM wO9XL7emjPnZ8HGu6oKq1coTGcjzhWIN+nVqjQMKGvLpyCSIvq07y3mu+RdNJGam9+e4 j+eA== X-Gm-Message-State: AKwxytdCPMGfZqcpYzkOnphXIk6jWfS23PyvYAWoecSVpillswkXCpqK ELMCnINn3WlGTNwNaes4knBEL23H X-Google-Smtp-Source: AH8x2254VvivIfKucCxq+8mMeCTF4z31yySyx/re6+v1lD89YUNLwnok4gcahBFkWGoCiHeXeSm74A== X-Received: by 10.107.8.148 with SMTP id h20mr9302520ioi.204.1516646523582; Mon, 22 Jan 2018 10:42:03 -0800 (PST) Received: from mail-io0-f174.google.com (mail-io0-f174.google.com. [209.85.223.174]) by smtp.gmail.com with ESMTPSA id f7sm8494226iod.60.2018.01.22.10.42.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 22 Jan 2018 10:42:03 -0800 (PST) Received: by mail-io0-f174.google.com with SMTP id t22so10461435ioa.7; Mon, 22 Jan 2018 10:42:02 -0800 (PST) X-Received: by 10.107.20.200 with SMTP id 191mr9547916iou.239.1516646522583; Mon, 22 Jan 2018 10:42:02 -0800 (PST) MIME-Version: 1.0 Received: by 10.107.157.12 with HTTP; Mon, 22 Jan 2018 10:41:41 -0800 (PST) In-Reply-To: <20180122180523.GH55707@kib.kiev.ua> References: <201801220244.w0M2if3I083081@repo.freebsd.org> <20180122102639.GD55707@kib.kiev.ua> <20180122155307.GG55707@kib.kiev.ua> <20180122180523.GH55707@kib.kiev.ua> From: Kyle Evans Date: Mon, 22 Jan 2018 12:41:41 -0600 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: svn commit: r328240 - in head: etc/mtree lib lib/libc/regex lib/libc/tests/regex lib/libregex lib/libregex/tests share/mk To: Konstantin Belousov Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers Content-Type: text/plain; charset="UTF-8" X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 22 Jan 2018 18:42:13 -0000 On Mon, Jan 22, 2018 at 12:05 PM, Konstantin Belousov wrote: > On Mon, Jan 22, 2018 at 11:43:34AM -0600, Kyle Evans wrote: >> On Mon, Jan 22, 2018 at 9:53 AM, Konstantin Belousov >> wrote: >> > On Mon, Jan 22, 2018 at 08:05:30AM -0600, Kyle Evans wrote: >> >> On Mon, Jan 22, 2018 at 4:26 AM, Konstantin Belousov >> >> wrote: >> >> > On Mon, Jan 22, 2018 at 02:44:41AM +0000, Kyle Evans wrote: >> >> >> Author: kevans >> >> >> Date: Mon Jan 22 02:44:41 2018 >> >> >> New Revision: 328240 >> >> >> URL: https://svnweb.freebsd.org/changeset/base/328240 >> >> >> >> >> >> Log: >> >> >> Add libregex, connect it to the build >> >> >> >> >> >> libregex is a regex(3) implementation intended to feature GNU extensions and >> >> >> any other non-POSIX compliant extensions that are deemed worthy. >> >> >> >> >> >> These extensions are separated out into a separate library for the sake of >> >> >> not cluttering up libc further with them as well as not deteriorating the >> >> >> speed (or lack thereof) of the libc implementation. >> >> >> >> >> >> libregex is implemented as a build of the libc implementation with LIBREGEX >> >> >> defined to distinguish this from a libc build. The reasons for >> >> >> implementation like this are two-fold: >> >> >> >> >> >> 1.) Maintenance- This reduces the overhead induced by adding yet another >> >> >> regex implementation to base. >> >> >> >> >> >> 2.) Ease of use- Flipping on GNU extensions will be as simple as linking >> >> >> against libregex, and POSIX-compliant compilations can be guaranteed with a >> >> >> REG_POSIX cflag that should be ignored by libc/regex and disables extensions >> >> >> in libregex. It is also easier to keep REG_POSIX sane and POSIX pure when >> >> >> implemented in this fashion. >> >> > You are doing very fragile and unmaintainable trick on all consumers >> >> > there. Your libregex.so exports the same symbols under the same version >> >> > as the libc does. In other words, we now provide two binary-incompatible >> >> > callable symbols, and selection of the symbol by the consumer depends on >> >> > the DT_NEEDED order and interposing. For instance, if some program loads >> >> > a module linked to your libregex, the program behaviour suddenly changes. >> >> > >> >> > Since the library provides incompatible implementation, it must use >> >> > different versions for the symbols, at least to save others time to >> >> > debug the mess. >> >> >> >> What's the best way that you see, going forward? >> >> >> >> I'm inclined to throw a Symbol.map into libregex using FBSD_1.1... >> >> these interfaces are otherwise stable stable within the two respective >> >> libraries, so I don't see that causing too much pain in the future >> >> because symbol version changes should be rare. >> > I do not think this is wise to create contention on the standard FreeBSD' >> > version namespace. >> > >> >> >> >> On the other hand, I could see wanting to use something more like >> >> FBSD_LIBREGEX_1.0 so that if the situation does come up one doesn't >> >> need to double-check that they're not colliding with the other >> >> implementation. >> > I like this more. We still have to carry that symbols with the current >> > behaviour forever, but at least they would no longer conflict with the >> > libc' symbols for dynamic linking. >> >> Right- that makes sense. Would you object to the following patch? The >> versioning was botched in the first place because of no VERSION_DEF. >> I've also dropped the FBSD_ prefix from my previous mention of it >> because there seems to be no good justification or precedent for it >> elsewhere in the tree that I've found. > This looks fine. > > I would suggest to add the explanation why a different version name was > used there, in particular, to highlight that the symbols otherwise > conflict with the symbols from libc. >> Committed as r328263 with explanation in the symbol map for the difference from libc. Thanks!