On Mon, Jan 22, 2018 at 08:05:30AM -0600, Kyle Evans wrote: > On Mon, Jan 22, 2018 at 4:26 AM, Konstantin Belousov > <kostik...@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. 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. _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
