From owner-svn-src-all@freebsd.org Mon Jan 22 14:05:53 2018 Return-Path: Delivered-To: svn-src-all@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 E7319EC2B84; Mon, 22 Jan 2018 14:05:53 +0000 (UTC) (envelope-from byond.lenox@gmail.com) Received: from mail-it0-f50.google.com (mail-it0-f50.google.com [209.85.214.50]) (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 B7C3D7D4A0; Mon, 22 Jan 2018 14:05:53 +0000 (UTC) (envelope-from byond.lenox@gmail.com) Received: by mail-it0-f50.google.com with SMTP id w14so9815145itc.3; Mon, 22 Jan 2018 06:05:53 -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=WQdKB8qoqmKy9P2EtM8/yxIko0OzDoWzdEkM08fLKcI=; b=N5vNaiJKDT3e3NO29v+MsXyKlCseNK3KsKIKcRcT8IFGTT9BtKFgww/juCSWcgngjl 7sUSV29RCUTIgxHjk/dvJX48LB10j6qug9ADITQWvvZjsV67En880Mnta7jQnW3G5uiq OZ1a+eFLNWo+BnE8usxGBGicMVXgcxNkTOqtCsL0WG39rL18cYQfDgXCGWin6qR3XElF ZotV2j26rQArz3XgIl42IwdkXcIGtCtP0CDVV1uMFR17FGwLnKRgDy5PEZNs+luYamoV IoprkE/N/hp4n2bA8BM5E7ZRf009FxqNPE1TWyPXc6OGEr0h6bMdHqlQx+mKHUApjNc0 82mw== X-Gm-Message-State: AKwxytflPXvj5NHAdJoIH+yoH7qXvTR7S55+QlL7aForQpKF5c/1FGHp 6JeePL40uyP4WMjjurLVONJ6rGFb X-Google-Smtp-Source: AH8x226O75yt6LZ1jiDRmRHuldSrMwi8a6co+uAc9B5hy8P2K9Z7H6K2F9H+ZZLABxni4W/K4w30+g== X-Received: by 10.36.211.142 with SMTP id n136mr7929656itg.146.1516629951724; Mon, 22 Jan 2018 06:05:51 -0800 (PST) Received: from mail-it0-f51.google.com (mail-it0-f51.google.com. [209.85.214.51]) by smtp.gmail.com with ESMTPSA id c194sm3826988itb.20.2018.01.22.06.05.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 22 Jan 2018 06:05:51 -0800 (PST) Received: by mail-it0-f51.google.com with SMTP id x42so9967715ita.4; Mon, 22 Jan 2018 06:05:51 -0800 (PST) X-Received: by 10.36.52.8 with SMTP id z8mr7788909itz.130.1516629950818; Mon, 22 Jan 2018 06:05:50 -0800 (PST) MIME-Version: 1.0 Received: by 10.107.157.12 with HTTP; Mon, 22 Jan 2018 06:05:30 -0800 (PST) In-Reply-To: <20180122102639.GD55707@kib.kiev.ua> References: <201801220244.w0M2if3I083081@repo.freebsd.org> <20180122102639.GD55707@kib.kiev.ua> From: Kyle Evans Date: Mon, 22 Jan 2018 08:05:30 -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: src-committers , svn-src-all@freebsd.org, svn-src-head@freebsd.org Content-Type: text/plain; charset="UTF-8" X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 22 Jan 2018 14:05:54 -0000 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. 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.