On Thursday 29 May 2008 22:40:11 Brian Bevins wrote:
> Hi Jeff,
>
> I'm pretty sure stubs aren't the problem since neither BLT nor the perl
> Tcl module are compiled against the stub libraries. They are compiled
> against exactly the same version of libtcl8.4.so.
>
> When I examine the perl Tcl module library, I see a dependence on
> libtcl8.4.so:
>
> ldd
> <blah>/perl/5.8.2/lib/site_perl/5.8.2/i686-linux-thread-multi/auto/Tcl/Tcl.
>so libtcl8.4.so => <blah>/tcl/8.4/lib/libtcl8.4.so (0x00b62000) libc.so.6 =>
> /lib/tls/libc.so.6 (0x00577000)
> libdl.so.2 => /lib/libdl.so.2 (0x00e83000)
> libpthread.so.0 => /lib/tls/libpthread.so.0 (0x00708000)
> libm.so.6 => /lib/tls/libm.so.6 (0x00144000)
> /lib/ld-linux.so.2 (0x00785000)
>
> So as I understand it, when perl loads Tcl.so, that should force the
> dynamic loader to also load libtcl8.4.so. When I look at our BLT library:
>
> ldd <blah>/tcl/8.4/lib/libBLT24.so
> libc.so.6 => /lib/tls/libc.so.6 (0x0050d000)
> /lib/ld-linux.so.2 (0x00785000)
>
> It does not show any dependence on libtcl8.4.so (but I am certain that
> this is the version of Tcl against which it was compiled).
>
> However, when perl tries to load BLT inside the Tcl module, there are
> unresolved symbols. This script:
>
> #!<blah>/perl/5.8.2/bin/perl
> use Tcl::Tk;
> my $m = Tcl::Tk::MainWindow->new();
> my $i = $m->interp();
> $i->Eval('package require BLT');
>
> gives this error:
>
> ERROR: couldn't load file "<blah>/tcl/8.4/lib/libBLT24.so":
> <blah>/tcl/8.4/lib/libBLT24.so: undefined symbol: TclpRealloc
>
> If I use just Tcl rather than Tcl::Tk I get the same error. The missing
> symbol TclpRealloc is found in libtcl8.4.so:
>
> nm <blah>/tcl/8.4/lib/libtcl8.4.so | grep TclpRealloc
> 0007ade8 T TclpRealloc
>
> So my conclusion is that libBLT24.so needs to have libtcl8.4.so loaded
> even though it doesn't ask for it explicitly. Perl should be loading
> libtcl8.4.so since it is asked for by perl's Tcl.so. However, for some
> reason when I "use Tcl" from perl, libtcl8.4.so does not get loaded, and
> hence it is not there when libBLT24.so needs it.
>
> I think this confirmed by the fact that everything works if I force the
> loading of libtcl8.4.so like so:
>
> #!<blah>/perl/5.8.2/bin/perl
> use Tcl::Tk;
> my $m = Tcl::Tk::MainWindow->new();
IMO at the moment of this line both libtcl84.so and libtk84.so already loaded,
otherwise you'll get an error.
But I think that it is different
than /usr/csite/pubtools/tcl/8.4/lib/libtcl8.4.so
> my $i = $m->interp();
> $i->Eval('load /usr/csite/pubtools/tcl/8.4/lib/libtcl8.4.so Tcl');
> $i->Eval('package require BLT');
>
> Then I get no error. What I don't understand is why I have to do that.
> Perl should be loading libtcl8.4.so automatically, but for some reason
> it doesn't.
I think perl do load libtcl84..., but then you load different libtcl84 library
which have another missing symbol, i.e resolving goes okay, but you do get a
mess of some kind.
You should try isolate your libtcl-s and try to work with
only /usr/csite/pubtools/tcl/8.4/lib/libtcl8.4.so one.
> Is there any way to get perl to tell me exactly what libraries have been
> loaded? In Tcl I would use "info loaded" for this purpose.
dynaloader tracks loaded libraries internally, it do not track any shared
libraries that were loaded by library that it loaded
perl -MTcl::Tk -lwe 'print
join " ",keys %{DynaLoader::},";; ",qq/@DynaLoader::dl_shared_objects/'
dl_require_symbols dl_error dl_install_xsub dl_modules dl_find_symbol
boot_DynaLoader bootstrap dl_undef_symbols isa dl_load_file dl_librefs
dl_shared_objects
dl_unload_file ;;
/opt/perl-5.8.8/lib/site_perl/5.8.8/i686-linux/auto/Tcl/Tcl.so
BR,
Vadim.
