On Mon, Jan 22, 2018 at 12:05 PM, Konstantin Belousov <kostik...@gmail.com> 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 >> <kostik...@gmail.com> 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 >> >> <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. >> >> 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! _______________________________________________ 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"
