/*

** $Id: loadlib.c $

** Dynamic library loader for Lua

** See Copyright Notice in lua.h

**

** This module contains an implementation of loadlib for Unix systems

** that have dlfcn, an implementation for Windows, and a stub for other

** systems.

*/

#define loadlib_c

#define LUA_LIB

#include "lprefix.h"

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "lua.h"

#include "lauxlib.h"

#include "lualib.h"

/*

** LUA_CSUBSEP is the character that replaces dots in submodule names

** when searching for a C loader.

** LUA_LSUBSEP is the character that replaces dots in submodule names

** when searching for a Lua loader.

*/

#if !defined(LUA_CSUBSEP)

#define LUA_CSUBSEP   LUA_DIRSEP

#endif

#if !defined(LUA_LSUBSEP)

#define LUA_LSUBSEP   LUA_DIRSEP

#endif

/* prefix for open functions in C libraries */

#define LUA_POF   "luaopen_"

/* separator for open functions in C libraries */

#define LUA_OFSEP "_"

/*

** key for table in the registry that keeps handles

** for all loaded C libraries

*/

static const char *const CLIBS = "_CLIBS";

#define LIB_FAIL  "open"

#define setprogdir(L)           ((void)0)

/*

** Special type equivalent to '(void*)' for functions in gcc

** (to suppress warnings when converting function pointers)

*/

typedef void (*voidf)(void);

/*

** system-dependent functions

*/

/*

** unload library 'lib'

*/

static void lsys_unloadlib (void *lib);

/*

** load C library in file 'path'. If 'seeglb', load with all names in

** the library global.

** Returns the library; in case of error, returns NULL plus an

** error string in the stack.

*/

static void *lsys_load (lua_State *L, const char *path, int seeglb);

/*

** Try to find a function named 'sym' in library 'lib'.

** Returns the function; in case of error, returns NULL plus an

** error string in the stack.

*/

static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym);

#if defined(LUA_USE_DLOPEN) /* { */

/*

** {========================================================================

** This is an implementation of loadlib based on the dlfcn interface.

** The dlfcn interface is available in Linux, SunOS, Solaris, IRIX, FreeBSD,

** NetBSD, AIX 4.2, HPUX 11, and  probably most other Unix flavors, at least

** as an emulation layer on top of native functions.

** =========================================================================

*/

#include <dlfcn.h>

/*

** Macro to convert pointer-to-void* to pointer-to-function. This cast

** is undefined according to ISO C, but POSIX assumes that it works.

** (The '__extension__' in gnu compilers is only to avoid warnings.)

*/

#if defined(__GNUC__)

#define cast_func(p) (__extension__ (lua_CFunction)(p))

#else

#define cast_func(p) ((lua_CFunction)(p))

#endif

static void lsys_unloadlib (void *lib) {

  dlclose(lib);

}

static void *lsys_load (lua_State *L, const char *path, int seeglb) {

  void *lib = dlopen(path, RTLD_NOW | (seeglb ? RTLD_GLOBAL : RTLD_LOCAL));

  if (l_unlikely(lib == NULL))

    lua_pushstring(L, dlerror());

  return lib;

}

static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {

  lua_CFunction f = cast_func(dlsym(lib, sym));

  if (l_unlikely(f == NULL))

    lua_pushstring(L, dlerror());

  return f;

}

/* }====================================================== */

#elif defined(LUA_DL_DLL) /* }{ */

/*

** {======================================================================

** This is an implementation of loadlib for Windows using native functions.

** =======================================================================

*/

#include <windows.h>

/*

** optional flags for LoadLibraryEx

*/

#if !defined(LUA_LLE_FLAGS)

#define LUA_LLE_FLAGS 0

#endif

#undef setprogdir

/*

** Replace in the path (on the top of the stack) any occurrence

** of LUA_EXEC_DIR with the executable's path.

*/

static void setprogdir (lua_State *L) {

  char buff[MAX_PATH + 1];

  char *lb;

  DWORD nsize = sizeof(buff)/sizeof(char);

  DWORD n = GetModuleFileNameA(NULL, buff, nsize);  /* get exec. name */

  if (n == 0 || n == nsize || (lb = strrchr(buff, '\\')) == NULL)

    luaL_error(L, "unable to get ModuleFileName");

  else {

    *lb = '\0';  /* cut name on the last '\\' to get the path */

    luaL_gsub(L, lua_tostring(L, -1), LUA_EXEC_DIR, buff);

    lua_remove(L, -2);  /* remove original string */

  }

}

static void pusherror (lua_State *L) {

  int error = GetLastError();

  char buffer[128];

  if (FormatMessageA(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,

      NULL, error, 0, buffer, sizeof(buffer)/sizeof(char), NULL))

    lua_pushstring(L, buffer);

  else

    lua_pushfstring(L, "system error %d\n", error);

}

static void lsys_unloadlib (void *lib) {

  FreeLibrary((HMODULE)lib);

}

static void *lsys_load (lua_State *L, const char *path, int seeglb) {

  HMODULE lib = LoadLibraryExA(path, NULL, LUA_LLE_FLAGS);

  (void)(seeglb);  /* not used: symbols are 'global' by default */

  if (lib == NULL) pusherror(L);

  return lib;

}

static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {

  lua_CFunction f = (lua_CFunction)(voidf)GetProcAddress((HMODULE)lib, sym);

  if (f == NULL) pusherror(L);

  return f;

}

/* }====================================================== */

#else       /* }{ */

/*

** {======================================================

** Fallback for other systems

** =======================================================

*/

#undef LIB_FAIL

#define LIB_FAIL  "absent"

#define DLMSG "dynamic libraries not enabled; check your Lua installation"

static void lsys_unloadlib (void *lib) {

  (void)(lib);  /* not used */

}

static void *lsys_load (lua_State *L, const char *path, int seeglb) {

  (void)(path); (void)(seeglb);  /* not used */

  lua_pushliteral(L, DLMSG);

  return NULL;

}

static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {

  (void)(lib); (void)(sym);  /* not used */

  lua_pushliteral(L, DLMSG);

  return NULL;

}

/* }====================================================== */

#endif        /* } */

/*

** {==================================================================

** Set Paths

** ===================================================================

*/

/*

** LUA_PATH_VAR and LUA_CPATH_VAR are the names of the environment

** variables that Lua check to set its paths.

*/

#if !defined(LUA_PATH_VAR)

#define LUA_PATH_VAR    "LUA_PATH"

#endif

#if !defined(LUA_CPATH_VAR)

#define LUA_CPATH_VAR   "LUA_CPATH"

#endif

/*

** return registry.LUA_NOENV as a boolean

*/

static int noenv (lua_State *L) {

  int b;

  lua_getfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");

  b = lua_toboolean(L, -1);

  lua_pop(L, 1);  /* remove value */

  return b;

}

/*

** Set a path. (If using the default path, assume it is a string

** literal in C and create it as an external string.)

*/

static void setpath (lua_State *L, const char *fieldname,

                                   const char *envname,

                                   const char *dft) {

  const char *dftmark;

  const char *nver = lua_pushfstring(L, "%s%s", envname, LUA_VERSUFFIX);

  const char *path = getenv(nver);  /* try versioned name */

  if (path == NULL)  /* no versioned environment variable? */

    path = getenv(envname);  /* try unversioned name */

  if (path == NULL || noenv(L))  /* no environment variable? */

    lua_pushextlstring(L, dft, strlen(dft), NULL, NULL);  /* use default */

  else if ((dftmark = strstr(path, LUA_PATH_SEP LUA_PATH_SEP)) == NULL)

    lua_pushstring(L, path);  /* nothing to change */

  else {  /* path contains a ";;": insert default path in its place */

    size_t len = strlen(path);

    luaL_Buffer b;

    luaL_buffinit(L, &b);

    if (path < dftmark) {  /* is there a prefix before ';;'? */

      luaL_addlstring(&b, path, dftmark - path);  /* add it */

      luaL_addchar(&b, *LUA_PATH_SEP);

    }

    luaL_addstring(&b, dft);  /* add default */

    if (dftmark < path + len - 2) {  /* is there a suffix after ';;'? */

      luaL_addchar(&b, *LUA_PATH_SEP);

      luaL_addlstring(&b, dftmark + 2, (path + len - 2) - dftmark);

    }

    luaL_pushresult(&b);

  }

  setprogdir(L);

  lua_setfield(L, -3, fieldname);  /* package[fieldname] = path value */

  lua_pop(L, 1);  /* pop versioned variable name ('nver') */

}

/* }================================================================== */

/*

** return registry.CLIBS[path]

*/

static void *checkclib (lua_State *L, const char *path) {

  void *plib;

  lua_getfield(L, LUA_REGISTRYINDEX, CLIBS);

  lua_getfield(L, -1, path);

  plib = lua_touserdata(L, -1);  /* plib = CLIBS[path] */

  lua_pop(L, 2);  /* pop CLIBS table and 'plib' */

  return plib;

}

/*

** registry.CLIBS[path] = plib        -- for queries

** registry.CLIBS[#CLIBS + 1] = plib  -- also keep a list of all libraries

*/

static void addtoclib (lua_State *L, const char *path, void *plib) {

  lua_getfield(L, LUA_REGISTRYINDEX, CLIBS);

  lua_pushlightuserdata(L, plib);

  lua_pushvalue(L, -1);

  lua_setfield(L, -3, path);  /* CLIBS[path] = plib */

  lua_rawseti(L, -2, luaL_len(L, -2) + 1);  /* CLIBS[#CLIBS + 1] = plib */

  lua_pop(L, 1);  /* pop CLIBS table */

}

/*

** __gc tag method for CLIBS table: calls 'lsys_unloadlib' for all lib

** handles in list CLIBS

*/

static int gctm (lua_State *L) {

  lua_Integer n = luaL_len(L, 1);

  for (; n >= 1; n--) {  /* for each handle, in reverse order */

    lua_rawgeti(L, 1, n);  /* get handle CLIBS[n] */

    lsys_unloadlib(lua_touserdata(L, -1));

    lua_pop(L, 1);  /* pop handle */

  }

  return 0;

}

/* error codes for 'lookforfunc' */

#define ERRLIB    1

#define ERRFUNC   2

/*

** Look for a C function named 'sym' in a dynamically loaded library

** 'path'.

** First, check whether the library is already loaded; if not, try

** to load it.

** Then, if 'sym' is '*', return true (as library has been loaded).

** Otherwise, look for symbol 'sym' in the library and push a

** C function with that symbol.

** Return 0 and 'true' or a function in the stack; in case of

** errors, return an error code and an error message in the stack.

*/

static int lookforfunc (lua_State *L, const char *path, const char *sym) {

  void *reg = checkclib(L, path);  /* check loaded C libraries */

  if (reg == NULL) {  /* must load library? */

    reg = lsys_load(L, path, *sym == '*');  /* global symbols if 'sym'=='*' */

    if (reg == NULL) return ERRLIB;  /* unable to load library */

    addtoclib(L, path, reg);

  }

  if (*sym == '*') {  /* loading only library (no function)? */

    lua_pushboolean(L, 1);  /* return 'true' */

    return 0;  /* no errors */

  }

  else {

    lua_CFunction f = lsys_sym(L, reg, sym);

    if (f == NULL)

      return ERRFUNC;  /* unable to find function */

    lua_pushcfunction(L, f);  /* else create new function */

    return 0;  /* no errors */

  }

}

static int ll_loadlib (lua_State *L) {

  const char *path = luaL_checkstring(L, 1);

  const char *init = luaL_checkstring(L, 2);

  int stat = lookforfunc(L, path, init);

  if (l_likely(stat == 0))  /* no errors? */

    return 1;  /* return the loaded function */

  else {  /* error; error message is on stack top */

    luaL_pushfail(L);

    lua_insert(L, -2);

    lua_pushstring(L, (stat == ERRLIB) ?  LIB_FAIL : "init");

    return 3;  /* return fail, error message, and where */

  }

}

/*

** {======================================================

** 'require' function

** =======================================================

*/

static int readable (const char *filename) {

  FILE *f = fopen(filename, "r");  /* try to open file */

  if (f == NULL) return 0;  /* open failed */

  fclose(f);

  return 1;

}

/*

** Get the next name in '*path' = 'name1;name2;name3;...', changing

** the ending ';' to '\0' to create a zero-terminated string. Return

** NULL when list ends.

*/

static const char *getnextfilename (char **path, char *end) {

  char *sep;

  char *name = *path;

  if (name == end)

    return NULL;  /* no more names */

  else if (*name == '\0') {  /* from previous iteration? */

    *name = *LUA_PATH_SEP;  /* restore separator */

    name++;  /* skip it */

  }

  sep = strchr(name, *LUA_PATH_SEP);  /* find next separator */

  if (sep == NULL)  /* separator not found? */

    sep = end;  /* name goes until the end */

  *sep = '\0';  /* finish file name */

  *path = sep;  /* will start next search from here */

  return name;

}

/*

** Given a path such as ";blabla.so;blublu.so", pushes the string

**

** no file 'blabla.so'

**  no file 'blublu.so'

*/

static void pusherrornotfound (lua_State *L, const char *path) {

  luaL_Buffer b;

  luaL_buffinit(L, &b);

  luaL_addstring(&b, "no file '");

  luaL_addgsub(&b, path, LUA_PATH_SEP, "'\n\tno file '");

  luaL_addstring(&b, "'");

  luaL_pushresult(&b);

}

static const char *searchpath (lua_State *L, const char *name,

                                             const char *path,

                                             const char *sep,

                                             const char *dirsep) {

  luaL_Buffer buff;

  char *pathname;  /* path with name inserted */

  char *endpathname;  /* its end */

  const char *filename;

  /* separator is non-empty and appears in 'name'? */

  if (*sep != '\0' && strchr(name, *sep) != NULL)

    name = luaL_gsub(L, name, sep, dirsep);  /* replace it by 'dirsep' */

  luaL_buffinit(L, &buff);

  /* add path to the buffer, replacing marks ('?') with the file name */

  luaL_addgsub(&buff, path, LUA_PATH_MARK, name);

  luaL_addchar(&buff, '\0');

  pathname = luaL_buffaddr(&buff);  /* writable list of file names */

  endpathname = pathname + luaL_bufflen(&buff) - 1;

  while ((filename = getnextfilename(&pathname, endpathname)) != NULL) {

    if (readable(filename))  /* does file exist and is readable? */

      return lua_pushstring(L, filename);  /* save and return name */

  }

  luaL_pushresult(&buff);  /* push path to create error message */

  pusherrornotfound(L, lua_tostring(L, -1));  /* create error message */

  return NULL;  /* not found */

}

static int ll_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 */

    luaL_pushfail(L);

    lua_insert(L, -2);

    return 2;  /* return fail + error message */

  }

}

static const char *findfile (lua_State *L, const char *name,

                                           const char *pname,

                                           const char *dirsep) {

  const char *path;

  lua_getfield(L, lua_upvalueindex(1), pname);

  path = lua_tostring(L, -1);

  if (l_unlikely(path == NULL))

    luaL_error(L, "'package.%s' must be a string", pname);

  return searchpath(L, name, path, ".", dirsep);

}

static int checkload (lua_State *L, int stat, const char *filename) {

  if (l_likely(stat)) {  /* module loaded successfully? */

    lua_pushstring(L, filename);  /* will be 2nd argument to module */

    return 2;  /* return open function and file name */

  }

  else

    return luaL_error(L, "error loading module '%s' from file '%s':\n\t%s",

                          lua_tostring(L, 1), filename, lua_tostring(L, -1));

}

static int searcher_Lua (lua_State *L) {

  const char *filename;

  const char *name = luaL_checkstring(L, 1);

  filename = findfile(L, name, "path", LUA_LSUBSEP);

  if (filename == NULL) return 1;  /* module not found in this path */

  return checkload(L, (luaL_loadfile(L, filename) == LUA_OK), filename);

}

/*

** Try to find a load function for module 'modname' at file 'filename'.

** First, change '.' to '_' in 'modname'; then, if 'modname' has

** the form X-Y (that is, it has an "ignore mark"), build a function

** name "luaopen_X" and look for it. (For compatibility, if that

** fails, it also tries "luaopen_Y".) If there is no ignore mark,

** look for a function named "luaopen_modname".

*/

static int loadfunc (lua_State *L, const char *filename, const char *modname) {

  const char *openfunc;

  const char *mark;

  modname = luaL_gsub(L, modname, ".", LUA_OFSEP);

  mark = strchr(modname, *LUA_IGMARK);

  if (mark) {

    int stat;

    openfunc = lua_pushlstring(L, modname, mark - modname);

    openfunc = lua_pushfstring(L, LUA_POF"%s", openfunc);

    stat = lookforfunc(L, filename, openfunc);

    if (stat != ERRFUNC) return stat;

    modname = mark + 1;  /* else go ahead and try old-style name */

  }

  openfunc = lua_pushfstring(L, LUA_POF"%s", modname);

  return lookforfunc(L, filename, openfunc);

}

static int searcher_C (lua_State *L) {

  const char *name = luaL_checkstring(L, 1);

  const char *filename = findfile(L, name, "cpath", LUA_CSUBSEP);

  if (filename == NULL) return 1;  /* module not found in this path */

  return checkload(L, (loadfunc(L, filename, name) == 0), filename);

}

static int searcher_Croot (lua_State *L) {

  const char *filename;

  const char *name = luaL_checkstring(L, 1);

  const char *p = strchr(name, '.');

  int stat;

  if (p == NULL) return 0;  /* is root */

  lua_pushlstring(L, name, p - name);

  filename = findfile(L, lua_tostring(L, -1), "cpath", LUA_CSUBSEP);

  if (filename == NULL) return 1;  /* root not found */

  if ((stat = loadfunc(L, filename, name)) != 0) {

    if (stat != ERRFUNC)

      return checkload(L, 0, filename);  /* real error */

    else {  /* open function not found */

      lua_pushfstring(L, "no module '%s' in file '%s'", name, filename);

      return 1;

    }

  }

  lua_pushstring(L, filename);  /* will be 2nd argument to module */

  return 2;

}

static int searcher_preload (lua_State *L) {

  const char *name = luaL_checkstring(L, 1);

  lua_getfield(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);

  if (lua_getfield(L, -1, name) == LUA_TNIL) {  /* not found? */

    lua_pushfstring(L, "no field package.preload['%s']", name);

    return 1;

  }

  else {

    lua_pushliteral(L, ":preload:");

    return 2;

  }

}

static void findloader (lua_State *L, const char *name) {

  int i;

  luaL_Buffer msg;  /* to build error message */

  /* push 'package.searchers' to index 3 in the stack */

  if (l_unlikely(lua_getfield(L, lua_upvalueindex(1), "searchers")

                 != LUA_TTABLE))

    luaL_error(L, "'package.searchers' must be a table");

  luaL_buffinit(L, &msg);

  luaL_addstring(&msg, "\n\t");  /* error-message prefix for first message */

  /*  iterate over available searchers to find a loader */

  for (i = 1; ; i++) {

    if (l_unlikely(lua_rawgeti(L, 3, i) == LUA_TNIL)) {  /* no more searchers? */

      lua_pop(L, 1);  /* remove nil */

      luaL_buffsub(&msg, 2);  /* remove last prefix */

      luaL_pushresult(&msg);  /* create error message */

      luaL_error(L, "module '%s' not found:%s", name, lua_tostring(L, -1));

    }

    lua_pushstring(L, name);

    lua_call(L, 1, 2);  /* call it */

    if (lua_isfunction(L, -2))  /* did it find a loader? */

      return;  /* module loader found */

    else if (lua_isstring(L, -2)) {  /* searcher returned error message? */

      lua_pop(L, 1);  /* remove extra return */

      luaL_addvalue(&msg);  /* concatenate error message */

      luaL_addstring(&msg, "\n\t");  /* prefix for next message */

    }

    else  /* no error message */

      lua_pop(L, 2);  /* remove both returns */

  }

}

static int ll_require (lua_State *L) {

  const char *name = luaL_checkstring(L, 1);

  lua_settop(L, 1);  /* LOADED table will be at index 2 */

  lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);

  lua_getfield(L, 2, name);  /* LOADED[name] */

  if (lua_toboolean(L, -1))  /* is it there? */

    return 1;  /* package is already loaded */

  /* else must load package */

  lua_pop(L, 1);  /* remove 'getfield' result */

  findloader(L, name);

  lua_rotate(L, -2, 1);  /* function <-> loader data */

  lua_pushvalue(L, 1);  /* name is 1st argument to module loader */

  lua_pushvalue(L, -3);  /* loader data is 2nd argument */

  /* stack: ...; loader data; loader function; mod. name; loader data */

  lua_call(L, 2, 1);  /* run loader to load module */

  /* stack: ...; loader data; result from loader */

  if (!lua_isnil(L, -1))  /* non-nil return? */

    lua_setfield(L, 2, name);  /* LOADED[name] = returned value */

  else

    lua_pop(L, 1);  /* pop nil */

  if (lua_getfield(L, 2, name) == LUA_TNIL) {   /* module set no value? */

    lua_pushboolean(L, 1);  /* use true as result */

    lua_copy(L, -1, -2);  /* replace loader result */

    lua_setfield(L, 2, name);  /* LOADED[name] = true */

  }

  lua_rotate(L, -2, 1);  /* loader data <-> module result  */

  return 2;  /* return module result and loader data */

}

/* }====================================================== */

static const luaL_Reg pk_funcs[] = {

  {"loadlib", ll_loadlib},

  {"searchpath", ll_searchpath},

  /* placeholders */

  {"preload", NULL},

  {"cpath", NULL},

  {"path", NULL},

  {"searchers", NULL},

  {"loaded", NULL},

  {NULL, NULL}

};

static const luaL_Reg ll_funcs[] = {

  {"require", ll_require},

  {NULL, NULL}

};

static void createsearcherstable (lua_State *L) {

  static const lua_CFunction searchers[] = {

    searcher_preload,

    searcher_Lua,

    searcher_C,

    searcher_Croot,

    NULL

  };

  int i;

  /* create 'searchers' table */

  lua_createtable(L, sizeof(searchers)/sizeof(searchers[0]) - 1, 0);

  /* fill it with predefined searchers */

  for (i=0; searchers[i] != NULL; i++) {

    lua_pushvalue(L, -2);  /* set 'package' as upvalue for all searchers */

    lua_pushcclosure(L, searchers[i], 1);

    lua_rawseti(L, -2, i+1);

  }

  lua_setfield(L, -2, "searchers");  /* put it in field 'searchers' */

}

/*

** create table CLIBS to keep track of loaded C libraries,

** setting a finalizer to close all libraries when closing state.

*/

static void createclibstable (lua_State *L) {

  luaL_getsubtable(L, LUA_REGISTRYINDEX, CLIBS);  /* create CLIBS table */

  lua_createtable(L, 0, 1);  /* create metatable for CLIBS */

  lua_pushcfunction(L, gctm);

  lua_setfield(L, -2, "__gc");  /* set finalizer for CLIBS table */

  lua_setmetatable(L, -2);

}

LUAMOD_API int luaopen_package (lua_State *L) {

  createclibstable(L);

  luaL_newlib(L, pk_funcs);  /* create 'package' table */

  createsearcherstable(L);

  /* set paths */

  setpath(L, "path", LUA_PATH_VAR, LUA_PATH_DEFAULT);

  setpath(L, "cpath", LUA_CPATH_VAR, LUA_CPATH_DEFAULT);

  /* store config information */

  lua_pushliteral(L, LUA_DIRSEP "\n" LUA_PATH_SEP "\n" LUA_PATH_MARK "\n"

                     LUA_EXEC_DIR "\n" LUA_IGMARK "\n");

  lua_setfield(L, -2, "config");

  /* set field 'loaded' */

  luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);

  lua_setfield(L, -2, "loaded");

  /* set field 'preload' */

  luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);

  lua_setfield(L, -2, "preload");

  lua_pushglobaltable(L);

  lua_pushvalue(L, -2);  /* set 'package' as upvalue for next lib */

  luaL_setfuncs(L, ll_funcs, 1);  /* open lib into global table */

  lua_pop(L, 1);  /* pop global table */

  return 1;  /* return 'package' table */

}