CODEWITHSUNDEEP
lua
liangdong from baidu
liangdong from baidu

Reputation: 351

lua5.2's error: multiple Lua VMs detected

I use 5.2 for learning recently, what I want to try like this:

Step 1, build a c module for lua:

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

static int add(lua_State *L) {
    int x = luaL_checkint(L, -2);
    int y = luaL_checkint(L, -1);
    lua_pushinteger(L, x + y);
    return 1;
}

static const struct luaL_Reg reg_lib[] = {
    {"add", add}
};

int luaopen_tool(lua_State *L) {
    luaL_newlib(L, reg_lib);
    lua_setglobal(L, "tool");
    return 0;
}

I compile and link it with liblua.a, and I'm sure it works well in lua script like "require("tool") tool.add(1, 2)"

Step 2, I write another C program that wants to require my c module in step 1 like this:

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

int main(int argc, char* const argv[]) {
    lua_State *L = luaL_newstate(); 
    luaL_requiref(L, "base", luaopen_base, 1);
    luaL_requiref(L, "package", luaopen_package, 1);
    lua_getglobal(L, "require");
    if (!lua_isfunction(L, -1)) {
        printf("require not found\n");
        return 2;
    }
    lua_pushstring(L, "tool");
    if (lua_pcall(L, 1, 1, 0) != LUA_OK) {
        printf("require_fail=%s\n", lua_tostring(L, -1));
        return 3;
    }
    lua_getfield(L, -1, "add");
    lua_pushinteger(L, 2);
    lua_pushinteger(L, 3);
    lua_pcall(L, 2, 1, 0);
    int n = luaL_checkint(L, -1);
    printf("n=%d\n", n);
    return 0;
}

I also compile & link with liblua.a, but error occurs when I run it: "require_fail=multiple Lua VMs detected"

Someone's blog said that in lua5.2, you should link c module and c host program both dynamicly, but not staticly.

is there someone that has the same problem, or is there somehing wrong in my code, thanks.

NOTICE:

the problem has been solved by compile main program with -Wl,-E, thanks a lot for all your help ^^.

Upvotes: 4

Views: 3769

Answers (1)

lhf
lhf

Reputation: 72312

Don't link your C module with liblua.a when you create a .so from it. For examples, see my page of Lua libraries: http://www.tecgraf.puc-rio.br/~lhf/ftp/lua/ . You can link liblua.a statically into your main program but you have to export its symbols by adding -Wl,-E at link time. That's how the Lua interpreter is built in Linux.

Upvotes: 5

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