/*
** Package library.
** Copyright (C) 2005-2025 Mike Pall. See Copyright Notice in luajit.h
**
** Major portions taken verbatim or adapted from the Lua interpreter.
** Copyright (C) 1994-2012 Lua.org, PUC-Rio. See Copyright Notice in lua.h
*/

#define lib_package_c
#define LUA_LIB

#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"

#include "lj_obj.h"
#include "lj_err.h"
#include "lj_lib.h"

/* ------------------------------------------------------------------------ */

/* Error codes for ll_loadfunc. */
#define PACKAGE_ERR_LIB     1
#define PACKAGE_ERR_FUNC    2
#define PACKAGE_ERR_LOAD    3

/* Redefined in platform specific part. */
#define PACKAGE_LIB_FAIL    "open"
#define setprogdir(L)        ((void)0)

/* Symbol name prefixes. */
#define SYMPREFIX_CF        "luaopen_%s"
#define SYMPREFIX_BC        "luaJIT_BC_%s"

#if LJ_TARGET_DLOPEN

#include <dlfcn.h>

static void ll_unloadlib(void *lib)
{
  dlclose(lib);
}

static void *ll_load(lua_State *L, const char *path, int gl)
{
  void *lib = dlopen(path, RTLD_NOW | (gl ? RTLD_GLOBAL : RTLD_LOCAL));
  if (lib == NULL) lua_pushstring(L, dlerror());
  return lib;
}

static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym)
{
  lua_CFunction f = (lua_CFunction)dlsym(lib, sym);
  if (f == NULL) lua_pushstring(L, dlerror());
  return f;
}

static const char *ll_bcsym(void *lib, const char *sym)
{
#if defined(RTLD_DEFAULT) && !defined(NO_RTLD_DEFAULT)
  if (lib == NULL) lib = RTLD_DEFAULT;
#elif LJ_TARGET_OSX || LJ_TARGET_BSD
  if (lib == NULL) lib = (void *)(intptr_t)-2;
#endif
  return (const char *)dlsym(lib, sym);
}

#elif LJ_TARGET_WINDOWS

#define WIN32_LEAN_AND_MEAN
#include <windows.h>

#ifndef GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS
#define GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS  4
#define GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT  2
BOOL WINAPI GetModuleHandleExA(DWORD, LPCSTR, HMODULE*);
#endif

wchar_t*
lj_utf8_utf16(const char *utf8, size_t *out_len)
{
    int size;
    wchar_t *u16 = NULL;
    size = MultiByteToWideChar(CP_UTF8, 0, utf8, -1, NULL, 0);
    u16 = size > 0 ? (wchar_t*) malloc(sizeof(wchar_t) * (size + 1)) : 0;
    if (!u16)
    {
        return NULL;
    }
    size = MultiByteToWideChar(CP_UTF8, 0, utf8, -1, u16, size);
    if (size > 0)
    {
        if (out_len)
        {
            *out_len = (size_t)size;
        }
    }
    else
    {
        free(u16);
        return NULL;
    }
    return u16;
}

char*
lj_utf16_utf8(const wchar_t *utf16, size_t *out_len)
{
    int   m, size = 0;
    char *utf8 = NULL;

    size = WideCharToMultiByte(CP_UTF8, 0, utf16, -1, NULL, 0, NULL, NULL);
    utf8 = size > 0 ? (char*) malloc(size+1) : 0;
    if (NULL == utf8 )
    {
        return NULL;
    }
    m = WideCharToMultiByte(CP_UTF8, 0, utf16, -1, utf8, size, NULL, NULL);
    if (m > 0 && m <= size)
    {
        if (out_len)
        {
            *out_len = (size_t)m;
        }
        utf8[m-1] = 0;
    }
    else
    {
        free(utf8);
        utf8 = NULL;
    }
    return utf8;
}

void *LJ_WIN_LOADLIBA(const char *path)
{
  DWORD err = GetLastError();
  HANDLE lib = NULL;
  wchar_t *wpath = lj_utf8_utf16(path, NULL);
  if (wpath) {
  #if LJ_TARGET_UWP  
    lib = LoadPackagedLibrary(wpath, 0);
  #else
    lib = LoadLibraryW(wpath);
  #endif
    free(wpath);
  }
  SetLastError(err);
  return lib;
}

#undef setprogdir

static void setprogdir(lua_State *L)
{
  wchar_t *lb;  
  wchar_t wpath[1024 + 1];  
  char buff[1024 + 1] = {0};
  DWORD nsize = 1024;
  DWORD n = GetModuleFileNameW(NULL, wpath, nsize);
  if (n == 0 || n == nsize || (lb = wcsrchr(wpath, L'\\')) == NULL) {
    luaL_error(L, "unable to get ModuleFileName");
  } else {
    *lb = '\0';
    WideCharToMultiByte(CP_UTF8, 0, wpath, -1, buff, nsize, NULL, NULL);
    luaL_gsub(L, lua_tostring(L, -1), LUA_EXECDIR, buff);
    lua_remove(L, -2);  /* remove original string */
  }
}

static void pusherror(lua_State *L)
{
  wchar_t wbuffer[128];
  char buffer[128*2];
  DWORD error = GetLastError();
#if LJ_TARGET_XBOXONE
  if (FormatMessageW(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,
      NULL, error, 0, wbuffer, sizeof(wbuffer)/sizeof(wchar_t), NULL) &&
      WideCharToMultiByte(CP_ACP, 0, wbuffer, 128, buffer, 128*2, NULL, NULL))
#else
  if (FormatMessageW(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,
      NULL, error, 0, wbuffer, sizeof(wbuffer)/sizeof(wchar_t), NULL) &&
      WideCharToMultiByte(CP_UTF8, 0, wbuffer, 128, buffer, 128*2, NULL, NULL))
#endif
    lua_pushstring(L, buffer);
  else
    lua_pushfstring(L, "system error %d\n", error);
}

static void ll_unloadlib(void *lib)
{
  FreeLibrary((HINSTANCE)lib);
}

static void *ll_load(lua_State *L, const char *path, int gl)
{
  HINSTANCE lib = LJ_WIN_LOADLIBA(path);
  if (lib == NULL) pusherror(L);
  UNUSED(gl);
  return lib;
}

static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym)
{
  lua_CFunction f = (lua_CFunction)GetProcAddress((HINSTANCE)lib, sym);
  if (f == NULL) pusherror(L);
  return f;
}

#if LJ_TARGET_UWP
EXTERN_C IMAGE_DOS_HEADER __ImageBase;
#endif

static const char *ll_bcsym(void *lib, const char *sym)
{
  if (lib) {
    return (const char *)GetProcAddress((HINSTANCE)lib, sym);
  } else {
#if LJ_TARGET_UWP
    return (const char *)GetProcAddress((HINSTANCE)&__ImageBase, sym);
#else
    HINSTANCE h = GetModuleHandleA(NULL);
    const char *p = (const char *)GetProcAddress(h, sym);
    if (p == NULL && GetModuleHandleExA(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS|GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT, (const char *)ll_bcsym, &h))
      p = (const char *)GetProcAddress(h, sym);
    return p;
#endif
  }
}

#else

#undef PACKAGE_LIB_FAIL
#define PACKAGE_LIB_FAIL    "absent"

#define DLMSG    "dynamic libraries not enabled; no support for target OS"

static void ll_unloadlib(void *lib)
{
  UNUSED(lib);
}

static void *ll_load(lua_State *L, const char *path, int gl)
{
  UNUSED(path); UNUSED(gl);
  lua_pushliteral(L, DLMSG);
  return NULL;
}

static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym)
{
  UNUSED(lib); UNUSED(sym);
  lua_pushliteral(L, DLMSG);
  return NULL;
}

static const char *ll_bcsym(void *lib, const char *sym)
{
  UNUSED(lib); UNUSED(sym);
  return NULL;
}

#endif

/* ------------------------------------------------------------------------ */

static void **ll_register(lua_State *L, const char *path)
{
  void **plib;
  lua_pushfstring(L, "LOADLIB: %s", path);
  lua_gettable(L, LUA_REGISTRYINDEX);  /* check library in registry? */
  if (!lua_isnil(L, -1)) {  /* is there an entry? */
    plib = (void **)lua_touserdata(L, -1);
  } else {  /* no entry yet; create one */
    lua_pop(L, 1);
    plib = (void **)lua_newuserdata(L, sizeof(void *));
    *plib = NULL;
    luaL_setmetatable(L, "_LOADLIB");
    lua_pushfstring(L, "LOADLIB: %s", path);
    lua_pushvalue(L, -2);
    lua_settable(L, LUA_REGISTRYINDEX);
  }
  return plib;
}

static const char *mksymname(lua_State *L, const char *modname, const char *prefix)
{
  const char *funcname;
  const char *mark = strchr(modname, *LUA_IGMARK);
  if (mark) modname = mark + 1;
  funcname = luaL_gsub(L, modname, ".", "_");
  funcname = lua_pushfstring(L, prefix, funcname);
  lua_remove(L, -2);  /* remove 'gsub' result */
  return funcname;
}

static int ll_loadfunc(lua_State *L, const char *path, const char *name, int r)
{
  void **reg;
  if (strlen(path) >= 4096) {
    lua_pushliteral(L, "path too long");
    return PACKAGE_ERR_LIB;
  }
  reg = ll_register(L, path);
  if (*reg == NULL) *reg = ll_load(L, path, (*name == '*'));
  if (*reg == NULL) {
    return PACKAGE_ERR_LIB;  /* Unable to load library. */
  } else if (*name == '*') {  /* Only load library into global namespace. */
    lua_pushboolean(L, 1);
    return 0;
  } else {
    const char *sym = r ? name : mksymname(L, name, SYMPREFIX_CF);
    lua_CFunction f = ll_sym(L, *reg, sym);
    if (f) {
      lua_pushcfunction(L, f);
      return 0;
    }
    if (!r) {
      const char *bcdata = ll_bcsym(*reg, mksymname(L, name, SYMPREFIX_BC));
      lua_pop(L, 1);
      if (bcdata) {
        if (luaL_loadbuffer(L, bcdata, ~(size_t)0, name) != 0)
          return PACKAGE_ERR_LOAD;
        return 0;
      }
    }
    return PACKAGE_ERR_FUNC;  /* Unable to find function. */
  }
}

static int lj_cf_package_loadlib(lua_State *L)
{
  const char *path = luaL_checkstring(L, 1);
  const char *init = luaL_checkstring(L, 2);
  int st = ll_loadfunc(L, path, init, 1);
  if (st == 0) {  /* no errors? */
    return 1;  /* return the loaded function */
  } else {  /* error; error message is on stack top */
    lua_pushnil(L);
    lua_insert(L, -2);
    lua_pushstring(L, (st == PACKAGE_ERR_LIB) ?  PACKAGE_LIB_FAIL : "init");
    return 3;  /* return nil, error message, and where */
  }
}

static int lj_cf_package_unloadlib(lua_State *L)
{
  void **lib = (void **)luaL_checkudata(L, 1, "_LOADLIB");
  if (*lib) ll_unloadlib(*lib);
  *lib = NULL;  /* mark library as closed */
  return 0;
}

/* ------------------------------------------------------------------------ */

static int readable(const char *filename)
{
  int ret = 1;
  FILE *f = NULL;
  wchar_t *wfname = NULL;
#ifdef _WIN32
  if ((wfname = lj_utf8_utf16(filename, NULL)))
  {
    f = _wfopen(wfname, L"r");  
  }
#else
  f = fopen(filename, "r");  /* try to open file */
#endif  
  if (f == NULL)
  {
    ret = 0;  /* open failed */
  }
  else
  {
    fclose(f);  
  }
  if (wfname)
  {
    free(wfname);
  }
  return ret;
}

static const char *pushnexttemplate(lua_State *L, const char *path)
{
  const char *l;
  while (*path == *LUA_PATHSEP) path++;  /* skip separators */
  if (*path == '\0') return NULL;  /* no more templates */
  l = strchr(path, *LUA_PATHSEP);  /* find next separator */
  if (l == NULL) l = path + strlen(path);
  lua_pushlstring(L, path, (size_t)(l - path));  /* template */
  return l;
}

static const char *searchpath (lua_State *L, const char *name,
                   const char *path, const char *sep,
                   const char *dirsep)
{
  luaL_Buffer msg;  /* to build error message */
  luaL_buffinit(L, &msg);
  if (*sep != '\0')  /* non-empty separator? */
    name = luaL_gsub(L, name, sep, dirsep);  /* replace it by 'dirsep' */
  while ((path = pushnexttemplate(L, path)) != NULL) {
    const char *filename = luaL_gsub(L, lua_tostring(L, -1),
                     LUA_PATH_MARK, name);
    lua_remove(L, -2);  /* remove path template */
    if (readable(filename))  /* does file exist and is readable? */
      return filename;  /* return that file name */
    lua_pushfstring(L, "\n\tno file " LUA_QS, filename);
    lua_remove(L, -2);  /* remove file name */
    luaL_addvalue(&msg);  /* concatenate error msg. entry */
  }
  luaL_pushresult(&msg);  /* create error message */
  return NULL;  /* not found */
}

static int lj_cf_package_searchpath(lua_State *L)
{
  const char *f = searchpath(L, luaL_checkstring(L, 1),
                luaL_checkstring(L, 2),
                luaL_optstring(L, 3, "."),
                luaL_optstring(L, 4, LUA_DIRSEP));
  if (f != NULL) {
    return 1;
  } else {  /* error message is on top of the stack */
    lua_pushnil(L);
    lua_insert(L, -2);
    return 2;  /* return nil + error message */
  }
}

static const char *findfile(lua_State *L, const char *name,
                const char *pname)
{
  const char *path;
  lua_getfield(L, LUA_ENVIRONINDEX, pname);
  path = lua_tostring(L, -1);
  if (path == NULL)
    luaL_error(L, LUA_QL("package.%s") " must be a string", pname);
  return searchpath(L, name, path, ".", LUA_DIRSEP);
}

static void loaderror(lua_State *L, const char *filename)
{
  luaL_error(L, "error loading module " LUA_QS " from file " LUA_QS ":\n\t%s",
         lua_tostring(L, 1), filename, lua_tostring(L, -1));
}

static int lj_cf_package_loader_lua(lua_State *L)
{
  const char *filename;
  const char *name = luaL_checkstring(L, 1);
  filename = findfile(L, name, "path");
  if (filename == NULL) return 1;  /* library not found in this path */
  if (luaL_loadfile(L, filename) != 0)
    loaderror(L, filename);
  return 1;  /* library loaded successfully */
}

static int lj_cf_package_loader_c(lua_State *L)
{
  const char *name = luaL_checkstring(L, 1);
  const char *filename = findfile(L, name, "cpath");
  if (filename == NULL) return 1;  /* library not found in this path */
  if (ll_loadfunc(L, filename, name, 0) != 0)
    loaderror(L, filename);
  return 1;  /* library loaded successfully */
}

static int lj_cf_package_loader_croot(lua_State *L)
{
  const char *filename;
  const char *name = luaL_checkstring(L, 1);
  const char *p = strchr(name, '.');
  int st;
  if (p == NULL) return 0;  /* is root */
  lua_pushlstring(L, name, (size_t)(p - name));
  filename = findfile(L, lua_tostring(L, -1), "cpath");
  if (filename == NULL) return 1;  /* root not found */
  if ((st = ll_loadfunc(L, filename, name, 0)) != 0) {
    if (st != PACKAGE_ERR_FUNC) loaderror(L, filename);  /* real error */
    lua_pushfstring(L, "\n\tno module " LUA_QS " in file " LUA_QS,
            name, filename);
    return 1;  /* function not found */
  }
  return 1;
}

static int lj_cf_package_loader_preload(lua_State *L)
{
  const char *name = luaL_checkstring(L, 1);
  lua_getfield(L, LUA_ENVIRONINDEX, "preload");
  if (!lua_istable(L, -1))
    luaL_error(L, LUA_QL("package.preload") " must be a table");
  lua_getfield(L, -1, name);
  if (lua_isnil(L, -1)) {  /* Not found? */
    const char *bcname = mksymname(L, name, SYMPREFIX_BC);
    const char *bcdata = ll_bcsym(NULL, bcname);
    if (bcdata == NULL || luaL_loadbuffer(L, bcdata, ~(size_t)0, name) != 0)
      lua_pushfstring(L, "\n\tno field package.preload['%s']", name);
  }
  return 1;
}

/* ------------------------------------------------------------------------ */

#define KEY_SENTINEL    (U64x(80000000,00000000)|'s')

static int lj_cf_package_require(lua_State *L)
{
  const char *name = luaL_checkstring(L, 1);
  int i;
  lua_settop(L, 1);  /* _LOADED table will be at index 2 */
  lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
  lua_getfield(L, 2, name);
  if (lua_toboolean(L, -1)) {  /* is it there? */
    if ((L->top-1)->u64 == KEY_SENTINEL)  /* check loops */
      luaL_error(L, "loop or previous error loading module " LUA_QS, name);
    return 1;  /* package is already loaded */
  }
  /* else must load it; iterate over available loaders */
  lua_getfield(L, LUA_ENVIRONINDEX, "loaders");
  if (!lua_istable(L, -1))
    luaL_error(L, LUA_QL("package.loaders") " must be a table");
  lua_pushliteral(L, "");  /* error message accumulator */
  for (i = 1; ; i++) {
    lua_rawgeti(L, -2, i);  /* get a loader */
    if (lua_isnil(L, -1))
      luaL_error(L, "module " LUA_QS " not found:%s",
         name, lua_tostring(L, -2));
    lua_pushstring(L, name);
    lua_call(L, 1, 1);  /* call it */
    if (lua_isfunction(L, -1))  /* did it find module? */
      break;  /* module loaded successfully */
    else if (lua_isstring(L, -1))  /* loader returned error message? */
      lua_concat(L, 2);  /* accumulate it */
    else
      lua_pop(L, 1);
  }
  (L->top++)->u64 = KEY_SENTINEL;
  lua_setfield(L, 2, name);  /* _LOADED[name] = sentinel */
  lua_pushstring(L, name);  /* pass name as argument to module */
  lua_call(L, 1, 1);  /* run loaded module */
  if (!lua_isnil(L, -1))  /* non-nil return? */
    lua_setfield(L, 2, name);  /* _LOADED[name] = returned value */
  lua_getfield(L, 2, name);
  if ((L->top-1)->u64 == KEY_SENTINEL) {   /* module did not set a value? */
    lua_pushboolean(L, 1);  /* use true as result */
    lua_pushvalue(L, -1);  /* extra copy to be returned */
    lua_setfield(L, 2, name);  /* _LOADED[name] = true */
  }
  lj_lib_checkfpu(L);
  return 1;
}

/* ------------------------------------------------------------------------ */

static void setfenv(lua_State *L)
{
  lua_Debug ar;
  if (lua_getstack(L, 1, &ar) == 0 ||
      lua_getinfo(L, "f", &ar) == 0 ||  /* get calling function */
      lua_iscfunction(L, -1))
    luaL_error(L, LUA_QL("module") " not called from a Lua function");
  lua_pushvalue(L, -2);
  lua_setfenv(L, -2);
  lua_pop(L, 1);
}

static void dooptions(lua_State *L, int n)
{
  int i;
  for (i = 2; i <= n; i++) {
    lua_pushvalue(L, i);  /* get option (a function) */
    lua_pushvalue(L, -2);  /* module */
    lua_call(L, 1, 0);
  }
}

static void modinit(lua_State *L, const char *modname)
{
  const char *dot;
  lua_pushvalue(L, -1);
  lua_setfield(L, -2, "_M");  /* module._M = module */
  lua_pushstring(L, modname);
  lua_setfield(L, -2, "_NAME");
  dot = strrchr(modname, '.');  /* look for last dot in module name */
  if (dot == NULL) dot = modname; else dot++;
  /* set _PACKAGE as package name (full module name minus last part) */
  lua_pushlstring(L, modname, (size_t)(dot - modname));
  lua_setfield(L, -2, "_PACKAGE");
}

static int lj_cf_package_module(lua_State *L)
{
  const char *modname = luaL_checkstring(L, 1);
  int lastarg = (int)(L->top - L->base);
  luaL_pushmodule(L, modname, 1);
  lua_getfield(L, -1, "_NAME");
  if (!lua_isnil(L, -1)) {  /* Module already initialized? */
    lua_pop(L, 1);
  } else {
    lua_pop(L, 1);
    modinit(L, modname);
  }
  lua_pushvalue(L, -1);
  setfenv(L);
  dooptions(L, lastarg);
  return LJ_52;
}

static int lj_cf_package_seeall(lua_State *L)
{
  luaL_checktype(L, 1, LUA_TTABLE);
  if (!lua_getmetatable(L, 1)) {
    lua_createtable(L, 0, 1); /* create new metatable */
    lua_pushvalue(L, -1);
    lua_setmetatable(L, 1);
  }
  lua_pushvalue(L, LUA_GLOBALSINDEX);
  lua_setfield(L, -2, "__index");  /* mt.__index = _G */
  return 0;
}

/* ------------------------------------------------------------------------ */

#define AUXMARK "\1"

static void setpath(lua_State *L, const char *fieldname, const char *envname, const char *def, int noenv)
{
  char *path = NULL;
  wchar_t *w_env = NULL;
  const wchar_t *wpath = NULL;
#if LJ_TARGET_CONSOLE
  UNUSED(envname);
#else
  w_env = lj_utf8_utf16(envname, NULL);
  wpath = w_env ? _wgetenv(w_env) : NULL;
  path = wpath ? lj_utf16_utf8(wpath, NULL) : NULL;
#endif
  if (path == NULL || noenv) {
    lua_pushstring(L, def);
  } else {
    const char *lpath = luaL_gsub(L, path, LUA_PATHSEP LUA_PATHSEP, LUA_PATHSEP AUXMARK LUA_PATHSEP);
    luaL_gsub(L, lpath, AUXMARK, def);
    lua_remove(L, -2);
  }
  setprogdir(L);
  lua_setfield(L, -2, fieldname);
  if (path)
  {
    free(path);
  }
  if (w_env)
  {
    free(w_env);
  }
}


static const luaL_Reg package_lib[] = {
  { "loadlib",    lj_cf_package_loadlib },
  { "searchpath",  lj_cf_package_searchpath },
  { "seeall",    lj_cf_package_seeall },
  { NULL, NULL }
};

static const luaL_Reg package_global[] = {
  { "module",    lj_cf_package_module },
  { "require",    lj_cf_package_require },
  { NULL, NULL }
};

static const lua_CFunction package_loaders[] =
{
  lj_cf_package_loader_preload,
  lj_cf_package_loader_lua,
  lj_cf_package_loader_c,
  lj_cf_package_loader_croot,
  NULL
};

LUALIB_API int luaopen_package(lua_State *L)
{
  int i;
  int noenv;
  luaL_newmetatable(L, "_LOADLIB");
  lj_lib_pushcf(L, lj_cf_package_unloadlib, 1);
  lua_setfield(L, -2, "__gc");
  luaL_register(L, LUA_LOADLIBNAME, package_lib);
  lua_copy(L, -1, LUA_ENVIRONINDEX);
  lua_createtable(L, sizeof(package_loaders)/sizeof(package_loaders[0])-1, 0);
  for (i = 0; package_loaders[i] != NULL; i++) {
    lj_lib_pushcf(L, package_loaders[i], 1);
    lua_rawseti(L, -2, i+1);
  }
#if LJ_52
  lua_pushvalue(L, -1);
  lua_setfield(L, -3, "searchers");
#endif
  lua_setfield(L, -2, "loaders");
  lua_getfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
  noenv = lua_toboolean(L, -1);
  lua_pop(L, 1);
  setpath(L, "path", LUA_PATH, LUA_PATH_DEFAULT, noenv);
  setpath(L, "cpath", LUA_CPATH, LUA_CPATH_DEFAULT, noenv);
  lua_pushliteral(L, LUA_PATH_CONFIG);
  lua_setfield(L, -2, "config");
  luaL_findtable(L, LUA_REGISTRYINDEX, "_LOADED", 16);
  lua_setfield(L, -2, "loaded");
  luaL_findtable(L, LUA_REGISTRYINDEX, "_PRELOAD", 4);
  lua_setfield(L, -2, "preload");
  lua_pushvalue(L, LUA_GLOBALSINDEX);
  luaL_register(L, NULL, package_global);
  lua_pop(L, 1);
  return 1;
}

