Date: Mon, 22 Jan 2018 08:05:30 -0600 From: Kyle Evans <kevans@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r328240 - in head: etc/mtree lib lib/libc/regex lib/libc/tests/regex lib/libregex lib/libregex/tests share/mk Message-ID: <CACNAnaEWrWxruMgVKUyoE-sUqHv29ONhitHO6y25QnT3XD9AUA@mail.gmail.com> In-Reply-To: <20180122102639.GD55707@kib.kiev.ua> References: <201801220244.w0M2if3I083081@repo.freebsd.org> <20180122102639.GD55707@kib.kiev.ua>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, Jan 22, 2018 at 4:26 AM, Konstantin Belousov <kostikbel@gmail.com> 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.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CACNAnaEWrWxruMgVKUyoE-sUqHv29ONhitHO6y25QnT3XD9AUA>