Написание Си библиотеки для Lua

lualibtest.c

#include <unistd.h>
#include <time.h>
#include <math.h>
#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>
 
static int api_Sleep(lua_State* L) {
    int argc = lua_gettop(L);
    if (argc != 1) {
        lua_pushstring(L, "sleep function requres an argument");
        lua_error(L);
    }
    lua_Number argv1 = lua_tonumber(L, 1);
    if (argv1 <= 0) {
        lua_pushstring(L, "sleep funtion requires number, greather than zero");
        lua_error(L);
    }
    int sleepTime = floor(argv1 * 1000000);
    usleep(sleepTime);
    return 0;
}
 
static int api_Version(lua_State* L) {
    lua_pushstring(L, "LibTest 1.0.0");
    lua_pushnumber(L, 100);
    return 2;
}
 
static const struct luaL_Reg LuaLibCtx [] = {
    {"sleep", api_Sleep},
    {"version", api_Version},
    {NULL, NULL}
};
 
int extern luaopen_libtest(lua_State *L) {
    luaL_newlib(L, LuaLibCtx);
    return 1;
}

makefile

# LIBS="$(PREFIX)/"
INCS="$(PREFIX)/include/lua5.3/"
 
libtest.so: lualibtest.c
        gcc -shared -I$(INCS) $< -o $@

local lib = assert(require("libtest"))
local nixnow = function()
    return os.time(os.date("!*t"))
end
local a = nixnow()
print(lib.version())
lib.sleep(5)
print("Test done! " .. tostring(nixnow()-a))