Re: xpdf

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

Josh Triplett, le Mon 07 Jan 2008 21:36:59 -0800, a écrit :
> Josh Triplett wrote:
> > Josh Triplett wrote:
> >> Samuel Thibault wrote:
> >>> Josh Triplett, le Mon 07 Jan 2008 19:49:21 -0800, a écrit :
> >>>> All of the stubs exist as weak symbols, so linking to pthread will
> >>>> override the stubs in libpthread-stubs just like the ones in glibc.
> >>> The big difference is that glibc is guaranteed to be dynamically loaded
> >>> first, while libpthread-stubs is not necessarily, and this now have an
> >>> influence on weak symbol overrides, see
> >>>
> >>> http://sourceware.org/bugzilla/show_bug.cgi?id=3946
> >> Uh oh.  That looks bad for us too.
> > 
> > At least for Hurd, it looks like Debian's libc addresses your problem.
> > According to /usr/share/doc/libc6/changelog.Debian.gz:
> > 
> > glibc (2.5-5) unstable; urgency=low
> > [...]
> >   [ Michael Banck ]
> >   * patches/hurd-i386/local-dl-dynamic-weak.diff: new patch (turn
> >     _dl_dynamic_weak on by default for hurd-i386).
> > [...]
> >  -- Aurelien Jarno <aurel32@debian.org>  Mon, 30 Apr 2007 21:55:09 +0200
> > 
> > That doesn't help libpthread-stubs, though.  And if, as the bug you
> > referenced says, the ELF standards don't specify the behavior we expected
> > for weak symbols, I don't know that we have a solution.
> 
> ...which apparently already got mentioned earlier in the thread.  Sorry for
> the duplicate info; I should have read the entire thread before replying.

That said, now that you point out libpthread-stubs, maybe there's a
not so bad solution: make libc0.3-dev depend on libpthread-stubs0-dev,
and in libc.so, add AS_NEEDED ( /usr/lib/libpthread-stubs.so ) . That
way, if a library uses pthread functions without including -lpthread,
libpthread-stubs.so will automatically get linked in, providing the
necessary stubs, and things will behave correctly when used either in
a pthread program or in a non-pthread program.  The good thing in this
compared to the solutions I proposed earlier is that we don't have to
duplicate the work of libpthread-stubs, and when libpthread eventually
gets included in glibc, we can easily know which packages need to be
recompiled before putting back _dl_dynamic_weak to 0: it's simply all
those which depend on libpthread-stubs0!

Samuel