On 8/24/16 11:06 AM, Bryan Drewery wrote: > On 8/12/16 12:03 AM, Ed Schouten wrote: >> Author: ed >> Date: Fri Aug 12 07:03:58 2016 >> New Revision: 303988 >> URL: https://svnweb.freebsd.org/changeset/base/303988 >> >> Log: >> Reimplement dirname(3) to be thread-safe. >> >> Now that we've updated the prototypes of the basename(3) and dirname(3) >> functions to conform to POSIX, let's go ahead and reimplement dirname(3) >> in such a way that it's thread-safe, but also guaranteed to succeed. C >> libraries like glibc, musl and the one that's part of Solaris already >> follow such an approach. >> >> Move the existing implementation to another source file, >> freebsd11_dirname.c to keep existing users of the API that pass in a >> constant string happy, using symbol versioning. >> >> Put a new version of the function in dirname.c, obtained from CloudABI's >> C library. This version scans through the pathname string from left to >> right, normalizing it, while discarding the last pathname component. >> >> Reviewed by: emaste, jilles >> Differential Revision: https://reviews.freebsd.org/D7355 >> >> Added: >> head/lib/libc/gen/dirname_compat.c >> - copied, changed from r303452, head/lib/libc/gen/dirname.c >> Modified: >> head/lib/libc/gen/Makefile.inc >> head/lib/libc/gen/Symbol.map >> head/lib/libc/gen/dirname.3 >> head/lib/libc/gen/dirname.c >> > > [...] > >> >> Copied and modified: head/lib/libc/gen/dirname_compat.c (from r303452, >> head/lib/libc/gen/dirname.c) >> ============================================================================== >> --- head/lib/libc/gen/dirname.c Thu Jul 28 16:54:12 2016 >> (r303452, copy source) >> +++ head/lib/libc/gen/dirname_compat.c Fri Aug 12 07:03:58 2016 >> (r303988) >> @@ -26,7 +26,7 @@ __FBSDID("$FreeBSD$"); >> #include <sys/param.h> >> >> char * >> -dirname(char *path) >> +__freebsd11_dirname(char *path) >> { >> static char *dname = NULL; >> size_t len; >> @@ -75,3 +75,5 @@ dirname(char *path) >> dname[len] = '\0'; >> return (dname); >> } >> + >> +__sym_compat(dirname, __freebsd11_dirname, FBSD_1.0); >> > > This creates an interesting situation [1] that breaks building older > sources and installing them into a chroot. The dirname@FBSD_1.0 is > _not_ used in this case and isn't expected to be. This is coming up > most often lately for nanonbsd and staged installs. > > Example scenario: > > Host: Head after this commit > Src: stable/9 > Building to install on another system over NFS or chroot to tar, > whatever. Not trying to downgrade the host (though one report was trying > this too). > > Buildworld builds usr.bin/xinstall in the bootstrap-tools phase *for the > host* to run during the build and to use for installation later in > installworld. This uses *the host libc* and picks up the new > dirname@FBSD_1.5 symbol. > > The reasoning for this is so we can add new flags into the build that > install needs and have a newly boostrapped xinstall to use them. > > I mimiced this by building a releng/11.0 xinstall from head but the > result is the same for building an older stable/9: > >> # readelf -a /usr/obj/root/svn/releng/11.0/usr.bin/xinstall/xinstall | grep >> dirname >> 000000607200 000300000007 R_X86_64_JUMP_SLOT 0000000000000000 dirname + 0 >> 3: 0000000000000000 247 FUNC GLOBAL DEFAULT UND dirname@FBSD_1.5 >> (3) >> 108: 0000000000000000 247 FUNC GLOBAL DEFAULT UND dirname@@FBSD_1.5 > > Stable/9 too: >> ~/svn/stable/9/usr.bin/xinstall # readelf -a $(make whereobj)/xinstall | >> grep dirname >> 000000607200 000300000007 R_X86_64_JUMP_SLOT 0000000000000000 dirname + 0 >> 3: 0000000000000000 247 FUNC GLOBAL DEFAULT UND dirname@FBSD_1.5 >> (3) >> 108: 0000000000000000 247 FUNC GLOBAL DEFAULT UND dirname@@FBSD_1.5 > > > The xinstall being built lacks the fix to expect dirname/basename to > modify its arguments (r303450). > > So later when the *old* xinstall runs with *new host libc* in > installworld it gets the wrong result from basename/dirname: > >> ~/git/freebsd/lib/libcxxrt # >> INSTALL=/usr/obj/root/svn/releng/11.0/usr.bin/xinstall/xinstall make install >> DESTDIR=/tmp/blah >> /usr/obj/root/svn/releng/11.0/usr.bin/xinstall/xinstall -C -o root -g wheel >> -m 444 libcxxrt.a /tmp/blah/usr/lib/ >> /usr/obj/root/svn/releng/11.0/usr.bin/xinstall/xinstall -C -o root -g wheel >> -m 444 libcxxrt_p.a /tmp/blah/usr/lib/ >> /usr/obj/root/svn/releng/11.0/usr.bin/xinstall/xinstall -s -o root -g wheel >> -m 444 libcxxrt.so.1 /tmp/blah/lib/ >> /usr/obj/root/svn/releng/11.0/usr.bin/xinstall/xinstall -o root -g wheel -m >> 444 libcxxrt.so.1.debug /tmp/blah/usr/lib/debug/lib/ >> /usr/obj/root/svn/releng/11.0/usr.bin/xinstall/xinstall -l rs >> /tmp/blah/lib/libcxxrt.so.1 /tmp/blah/usr/lib/libcxxrt.so >> xinstall: symlink ../../lib/libcxxrt.so.1 -> /tmp/blah/usr/lib: File exists >> *** Error code 71 > > > So how can we fix? > > We can't expect older builds to expect basename(3)/dirname(3) to change > arguments. We could fix the tips of branches and all relengs/, but not > non-tips and I doubt so@ would care to EN something into all relengs/. > Nor can we change the xinstall bootstrapping in older builds for the > same reasons. We need a fix in head to handle this but I don't have any > ideas currently. > > > Interestingly I have an older stable/10 build that has an xinstall > before the dirname version was moved and it works fine as it is > defaulting to FBSD_1.0: > >> # readelf -a /usr/obj/root/svn/stable/10/tmp/legacy/usr/bin/install | grep >> dirname >> 112: 00000000006f4160 8 OBJECT LOCAL DEFAULT 15 dirname.dname >> 1893: 000000000040d950 268 FUNC GLOBAL DEFAULT 3 dirname > >> ~/git/freebsd/lib/libcxxrt # >> INSTALL=/usr/obj/root/svn/stable/10/tmp/legacy/usr/bin/install make install >> DESTDIR=/tmp/blah >> /usr/obj/root/svn/stable/10/tmp/legacy/usr/bin/install -C -o root -g wheel >> -m 444 libcxxrt.a /tmp/blah/usr/lib/ >> /usr/obj/root/svn/stable/10/tmp/legacy/usr/bin/install -C -o root -g wheel >> -m 444 libcxxrt_p.a /tmp/blah/usr/lib/ >> /usr/obj/root/svn/stable/10/tmp/legacy/usr/bin/install -s -o root -g wheel >> -m 444 libcxxrt.so.1 /tmp/blah/lib/ >> /usr/obj/root/svn/stable/10/tmp/legacy/usr/bin/install -o root -g wheel -m >> 444 libcxxrt.so.1.debug /tmp/blah/usr/lib/debug/lib/ >> /usr/obj/root/svn/stable/10/tmp/legacy/usr/bin/install -l rs >> /tmp/blah/lib/libcxxrt.so.1 /tmp/blah/usr/lib/libcxxrt.so > > But as soon as I do another buildworld on that checkout it will break > the binary. > > [1] > https://lists.freebsd.org/pipermail/freebsd-current/2016-August/063023.html >
I'm drawing blanks, hoping someone else has an idea. Otherwise I think we should revert this until a solution is thought up. Even putting a safe dirname(3)/basename(3) in xinstall won't help for the same reasons as listed. -- Regards, Bryan Drewery
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