Re: Lua Perl Bridge

[Rob Hoelz <rob@...>]

On Thu, 29 Apr 2010 21:50:55 -0700
Brian Maher <brian@brimworks.com> wrote:

> On Thu, Apr 29, 2010 at 9:02 AM, Rob Hoelz <rob@hoelzro.net> wrote:
> > lua: fail.lua:2: Can't load
> > '/usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/auto/B/B.so' for
> > module
> > B: /usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/auto/B/B.so:
> > undefined symbol: PL_opargs
> > at /usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/XSLoader.pm
> > line 64. at /usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/B.pm
> > line 316
> 
> The PL_opargs symbol should be coming from libperl.  If you are
> statically linking in libperl into your lua implementation of perl.so,
> there is a good possibility that the linker is optimizing out
> PL_opargs.  You could either build your perl with a libperl.so and
> link your perl.so as loaded by lua so it dynamically links against
> libperl.so, or you could tell your linker to link in the "whole
> archive" (-Wl,--whole-archive if you are using gcc frontend to ld).
> 
> All of this is just my guess though ;-).
> 
> Your project sounds really interesting to me.

The only library I have for Perl is libperl.so, and I link against that
with the following options (generated by perl -MExtUtils::Embed -e
ldopts):

-Wl,-E -Wl,-rpath,/usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/CORE -L/usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/CORE -lperl
-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc

Running ldd on my perl.so Lua module results in this output:

$ ldd perl.so
        linux-vdso.so.1 =>  (0x00007fffe49ff000)
        liblua-5.1.so => /usr/lib64/liblua-5.1.so (0x00007f6ababef000)
        libm.so.6 => /lib64/libm.so.6 (0x00007f6aba96a000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007f6aba766000)
        libperl.so => /usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/CORE/libperl.so (0x00007f6aba3c1000)
        libresolv.so.2 => /lib64/libresolv.so.2 (0x00007f6aba1a7000)
        libnsl.so.1 => /lib64/libnsl.so.1 (0x00007f6ab9f8e000)
        libcrypt.so.1 => /lib64/libcrypt.so.1 (0x00007f6ab9d57000)
        libutil.so.1 => /lib64/libutil.so.1 (0x00007f6ab9b53000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f6ab9937000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f6ab95be000)
        /lib64/ld-linux-x86-64.so.2 (0x00000038c7400000)
        libfreebl3.so => /lib64/libfreebl3.so (0x00007f6ab935e000)

> 
> > Compilation failed in require
> > at /usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/Scalar/Util/PP.pm
> > line 15. BEGIN failed--compilation aborted
> > at /usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/Scalar/Util/PP.pm
> > line 15. Compilation failed in require
> > at /usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/Scalar/Util.pm
> > line 21. Compilation failed in require at (eval 1) line 1.
> >
> > stack traceback:
> >        [C]: in function 'assert'
> >        fail.lua:2: in main chunk
> >        [C]: ?
> >
> > On Wed, 28 Apr 2010 16:08:42 -0500
> > Rob Hoelz <rob@hoelzro.net> wrote:
> >
> >> Hello lua-l,
> >>
> >> As indicated by my e-mail this morning, I'm writing a Lua-Perl
> >> bridge. I've run into a bit of a snag.
> >>
> >> I've written perl.c, which currently just allows you to evaluate
> >> strings of Perl code from Lua.  However, when I load a dynamic
> >> module from Perl (ex. Scalar::Util), I get errors relating to
> >> undefined symbols.  This probably stems from the fact that I have
> >> a standalone Lua interpreter loading a shared object (perl.so)
> >> that loads another shared object (libperl.so) that uses a dynamic
> >> loader (Perl's DynaLoader) to load another shared object (in the
> >> case of Scalar::Util, List/Util/Util.so).  I understand the basics
> >> of linking, but this is beyond my current knowledge.
> >>
> >> Attached are three files:
> >>
> >> - perl.c, which defines the Lua bindings to my Perl bridge.
> >> - Makefile - self explanatory
> >> - fail.lua - After running make, run 'lua fail.lua' and you'll see
> >> the errors.
> >>
> >> Note: If I compile my perl.c into standalone Lua, fail.lua passes
> >> fine.
> >>
> >> I should specify that I'm on 64-bit Fedora 12.
> >>
> >> If anyone with a greater knowledge of linking could take a look at
> >> this and give me any insight, I'd be very grateful.
> >>
> >> Thanks,
> >> Rob Hoelz
> >
> >
> 
> 
>

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