Re: Lua Perl Bridge

[Rob Hoelz <rob@...>]

Someone pointed out that there were no attachments; my mistake!  Also,
here is the error message I'm seeing:

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
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

local perl = require 'perl'
assert(perl.eval [[
require Scalar::Util;
]])

Attachment: Makefile
Description: Binary data

#include <EXTERN.h>
#include <perl.h>

#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>

static PerlInterpreter *my_perl;

/********************************* Utilities **********************************/
void push_sv(lua_State *L, SV *sv)
{
    if(! SvOK(sv)) {
	lua_pushnil(L);
    } else if(SvIOK(sv)) {
	lua_pushinteger(L, SvIV(sv));
    } else if(SvNOK(sv)) {
	lua_pushnumber(L, SvNV(sv));
    } else if(SvPOK(sv)) {
	lua_pushstring(L, SvPVX(sv));
    } else {
	printf("WTF!\n");
    }
}

/******************************** Metamethods *********************************/
static int perl_interp_gc(lua_State *L)
{
    perl_destruct(my_perl);
    perl_free(my_perl);
    PERL_SYS_TERM();

    return 0;
}

static perl_interp_index(lua_State *L)
{
    lua_getfenv(L, 1);
    lua_pushvalue(L, 2);
    lua_gettable(L, -2);

    return 1;
}

static luaL_Reg perl_interpreter_mmethods[] = {
    { "__gc", perl_interp_gc },
    { "__index", perl_interp_index },
    { NULL, NULL }
};

/********************************** Methods ***********************************/
static int perl_interp_eval(lua_State *L)
{
    SV *sv, *errsv;
    const char *perl = luaL_checkstring(L, 1);

    sv = eval_pv(perl, 0);
    errsv = get_sv("@", GV_ADD);
    if(SvOK(errsv) && SvCUR(errsv)) {
	lua_pushnil(L);
	push_sv(L, errsv);

	return 2;
    } else {
	push_sv(L, sv);
	return 1;
    }
}

static luaL_Reg perl_interpreter_methods[] = {
    { "eval", perl_interp_eval },
    { NULL, NULL }
};

/*************************** Module Initialization ****************************/

EXTERN_C void boot_DynaLoader(pTHX_ CV* cv);

static void xs_init(pTHX)
{
    char *file = __FILE__;

    newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader, file);
}

int luaopen_perl(lua_State *L)
{
    int fake_argc = 3;
    char *fake_argv[] = { "", "-e", "0" };

    lua_newuserdata(L, 0);

    PERL_SYS_INIT(&fake_argc, &fake_argv);
    my_perl = perl_alloc();
    perl_construct(my_perl);
    perl_parse(my_perl, xs_init, fake_argc, fake_argv, NULL);

    luaL_newmetatable(L, "PerlInterpreter");
    luaL_register(L, NULL, perl_interpreter_mmethods);
    lua_setmetatable(L, -2);

    lua_createtable(L, 0, sizeof(perl_interpreter_methods) / sizeof(luaL_Reg) - 1);
    luaL_register(L, NULL, perl_interpreter_methods);
    lua_setfenv(L, -2);

    lua_pushvalue(L, -1);
    lua_setglobal(L, "perl");

    return 1;
}

Attachment: signature.asc
Description: PGP signature