Date: Mon, 22 Jan 2018 11:43:34 -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: <CACNAnaGwTkhKqCsb420VnOW7vRmbURWtoV7rPwmK88f2-AQGnA@mail.gmail.com> In-Reply-To: <20180122155307.GG55707@kib.kiev.ua> References: <201801220244.w0M2if3I083081@repo.freebsd.org> <20180122102639.GD55707@kib.kiev.ua> <CACNAnaEWrWxruMgVKUyoE-sUqHv29ONhitHO6y25QnT3XD9AUA@mail.gmail.com> <20180122155307.GG55707@kib.kiev.ua>
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On Mon, Jan 22, 2018 at 9:53 AM, Konstantin Belousov <kostikbel@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 >> <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. > 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. diff --git a/lib/libregex/Makefile b/lib/libregex/Makefile index eb6b0b64650..8ac496dd9f7 100644 --- a/lib/libregex/Makefile +++ b/lib/libregex/Makefile @@ -9,7 +9,8 @@ SHLIB_MINOR= 0 CFLAGS+= -DLIBREGEX LIBC_SRCTOP= ${.CURDIR:H}/libc -SYMBOL_MAPS= ${SYM_MAPS} +VERSION_DEF= ${.CURDIR}/Versions.def +SYMBOL_MAPS= ${.CURDIR}/Symbol.map WARNS?= 2 #HAS_TESTS= diff --git a/lib/libregex/Symbol.map b/lib/libregex/Symbol.map new file mode 100644 index 00000000000..1b77bd85aca --- /dev/null +++ b/lib/libregex/Symbol.map @@ -0,0 +1,10 @@ +/* + * $FreeBSD$ + */ + +LIBREGEX_1.0 { + regcomp; + regerror; + regexec; + regfree; +}; diff --git a/lib/libregex/Versions.def b/lib/libregex/Versions.def new file mode 100644 index 00000000000..b6c84200762 --- /dev/null +++ b/lib/libregex/Versions.def @@ -0,0 +1,5 @@ +# $FreeBSD$ + +LIBREGEX_1.0 { +}; +
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