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/*

** $Id: loadlib.c,v 1.52 2006/04/10 18:27:23 roberto Exp $

** 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 Darwin (Mac OS X), an

** implementation for Windows, and a stub for other systems.

*/

#include <stdlib.h>

#include <string.h>

#define loadlib_c

#define LUA_LIB

#include "lauxlib.h"

#include "lobject.h"

#include "lua.h"

#include "lualib.h"

/* prefix for open functions in C libraries */

#define LUA_POF		"luaopen_"

/* separator for open functions in C libraries */

#define LUA_OFSEP	"_"

#define LIBPREFIX	"LOADLIB: "

#define POF		LUA_POF

#define LIB_FAIL	"open"

/* error codes for ll_loadfunc */

#define ERRLIB		1

#define ERRFUNC		2

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

static void ll_unloadlib (void *lib);

static void *ll_load (lua_State *L, const char *path);

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

#if defined(LUA_DL_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>

static void ll_unloadlib (void *lib) {

  dlclose(lib);

}

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

  void *lib = dlopen(path, RTLD_NOW);

  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;

}

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

#elif defined(LUA_DL_DLL)

/*

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

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

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

*/

#include <windows.h>

#undef setprogdir

static void setprogdir (lua_State *L) {

  char buff[MAX_PATH + 1];

  char *lb;

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

  DWORD n = GetModuleFileName(NULL, buff, nsize);

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

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

  else {

    *lb = '\0';

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

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

  }

}

static void pusherror (lua_State *L) {

  int error = GetLastError();

  char buffer[128];

  if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,

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

    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) {

  HINSTANCE lib = LoadLibrary(path);

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

  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;

}

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

#elif defined(LUA_DL_DYLD)

/*

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

** Native Mac OS X / Darwin Implementation

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

*/

#include <mach-o/dyld.h>

/* Mac appends a `_' before C function names */

#undef POF

#define POF	"_" LUA_POF

static void pusherror (lua_State *L) {

  const char *err_str;

  const char *err_file;

  NSLinkEditErrors err;

  int err_num;

  NSLinkEditError(&err, &err_num, &err_file, &err_str);

  lua_pushstring(L, err_str);

}

static const char *errorfromcode (NSObjectFileImageReturnCode ret) {

  switch (ret) {

    case NSObjectFileImageInappropriateFile:

      return "file is not a bundle";

    case NSObjectFileImageArch:

      return "library is for wrong CPU type";

    case NSObjectFileImageFormat:

      return "bad format";

    case NSObjectFileImageAccess:

      return "cannot access file";

    case NSObjectFileImageFailure:

    default:

      return "unable to load library";

  }

}

static void ll_unloadlib (void *lib) {

  NSUnLinkModule((NSModule)lib, NSUNLINKMODULE_OPTION_RESET_LAZY_REFERENCES);

}

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

  NSObjectFileImage img;

  NSObjectFileImageReturnCode ret;

  /* this would be a rare case, but prevents crashing if it happens */

  if(!_dyld_present()) {

    lua_pushliteral(L, "dyld not present");

    return NULL;

  }

  ret = NSCreateObjectFileImageFromFile(path, &img);

  if (ret == NSObjectFileImageSuccess) {

    NSModule mod = NSLinkModule(img, path, NSLINKMODULE_OPTION_PRIVATE |

                       NSLINKMODULE_OPTION_RETURN_ON_ERROR);

    NSDestroyObjectFileImage(img);

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

    return mod;

  }

  lua_pushstring(L, errorfromcode(ret));

  return NULL;

}

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

  NSSymbol nss = NSLookupSymbolInModule((NSModule)lib, sym);

  if (nss == NULL) {

    lua_pushfstring(L, "symbol " LUA_QS " not found", sym);

    return NULL;

  }

  return (lua_CFunction)NSAddressOfSymbol(nss);

}

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

#else

/*

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

** Fallback for other systems

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

*/

#undef LIB_FAIL

#define LIB_FAIL	"absent"

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

static void ll_unloadlib (void *lib) {

  (void)lib;  /* to avoid warnings */

}

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

  (void)path;  /* to avoid warnings */

  lua_pushliteral(L, DLMSG);

  return NULL;

}

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

  (void)lib; (void)sym;  /* to avoid warnings */

  lua_pushliteral(L, DLMSG);

  return NULL;

}

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

#endif

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

  void **plib;

  lua_pushfstring(L, "%s%s", LIBPREFIX, 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(const void *));

    *plib = NULL;

    luaL_getmetatable(L, "_LOADLIB");

    lua_setmetatable(L, -2);

    lua_pushfstring(L, "%s%s", LIBPREFIX, path);

    lua_pushvalue(L, -2);

    lua_settable(L, LUA_REGISTRYINDEX);

  }

  return plib;

}

/*

** __gc tag method: calls library's `ll_unloadlib' function with the lib

** handle

*/

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

  void **reg = ll_register(L, path);

  if (*reg == NULL) *reg = ll_load(L, path);

  if (*reg == NULL)

    return ERRLIB;  /* unable to load library */

  else {

    lua_CFunction f = ll_sym(L, *reg, sym);

    if (f == NULL)

      return ERRFUNC;  /* unable to find function */

    lua_pushcfunction(L, f);

    return 0;  /* return function */

  }

}

static int ll_loadlib (lua_State *L) {

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

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

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

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

    return 3;  /* return nil, 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;

}

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, l - path);  /* template */

  return l;

}

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

                                           const char *pname) {

  const char *path;

  name = luaL_gsub(L, name, ".", LUA_DIRSEP);

  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);

  lua_pushstring(L, "");  /* error accumulator */

  while ((path = pushnexttemplate(L, path)) != NULL) {

    const char *filename;

    filename = luaL_gsub(L, lua_tostring(L, -1), LUA_PATH_MARK, name);

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

      return filename;  /* return that file name */

    lua_pop(L, 2);  /* remove path template and file name */ 

    luaO_pushfstring(L, "\n\tno file " LUA_QS, filename);

    lua_concat(L, 2);

  }

  return NULL;  /* not found */

}

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 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 const char *mkfuncname (lua_State *L, const char *modname) {

  const char *funcname;

  const char *mark = strchr(modname, *LUA_IGMARK);

  if (mark) modname = mark + 1;

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

  funcname = lua_pushfstring(L, POF"%s", funcname);

  lua_remove(L, -2);  /* remove 'gsub' result */

  return funcname;

}

static int loader_C (lua_State *L) {

  const char *funcname;

  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 */

  funcname = mkfuncname(L, name);

  if (ll_loadfunc(L, filename, funcname) != 0)

    loaderror(L, filename);

  return 1;  /* library loaded successfully */

}

static int loader_Croot (lua_State *L) {

  const char *funcname;

  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");

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

  funcname = mkfuncname(L, name);

  if ((stat = ll_loadfunc(L, filename, funcname)) != 0) {

    if (stat != ERRFUNC) loaderror(L, filename);  /* real error */

    luaO_pushfstring(L, "\n\tno module " LUA_QS " in file " LUA_QS,

                        name, filename);

    return 1;  /* function not found */

  }

  return 1;

}

static int 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? */

    luaO_pushfstring(L, "\n\tno field package.preload['%s']", name);

  return 1;

}

static const int sentinel_ = 0;

#define sentinel	((void *)&sentinel_)

static int ll_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 (lua_touserdata(L, -1) == 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_pushstring(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);

  }

  lua_pushlightuserdata(L, 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 (lua_touserdata(L, -1) == 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 */

  }

  return 1;

}

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

/*

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

** 'module' function

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

*/

static void setfenv (lua_State *L) {

  lua_Debug ar;

  lua_getstack(L, 1, &ar);

  lua_getinfo(L, "f", &ar);

  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, dot - modname);

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

}

static int ll_module (lua_State *L) {

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

  int loaded = lua_gettop(L) + 1;  /* index of _LOADED table */

  lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");

  lua_getfield(L, loaded, modname);  /* get _LOADED[modname] */

  if (!lua_istable(L, -1)) {  /* not found? */

    lua_pop(L, 1);  /* remove previous result */

    /* try global variable (and create one if it does not exist) */

    if (luaL_findtable(L, LUA_GLOBALSINDEX, modname, 1) != NULL)

      return luaL_error(L, "name conflict for module " LUA_QS, modname);

    lua_pushvalue(L, -1);

    lua_setfield(L, loaded, modname);  /* _LOADED[modname] = new table */

  }

  /* check whether table already has a _NAME field */

  lua_getfield(L, -1, "_NAME");

  if (!lua_isnil(L, -1))  /* is table an initialized module? */

    lua_pop(L, 1);

  else {  /* no; initialize it */

    lua_pop(L, 1);

    modinit(L, modname);

  }

  lua_pushvalue(L, -1);

  setfenv(L);

  dooptions(L, loaded - 1);

  return 0;

}

static int ll_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;

}

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

/* auxiliary mark (for internal use) */

#define AUXMARK		"\1"

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

                                   const char *def) {

  const char *path = getenv(envname);

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

    lua_pushstring(L, def);  /* use default */

  else {

    /* replace ";;" by ";AUXMARK;" and then AUXMARK by default path */

    path = luaL_gsub(L, path, LUA_PATHSEP LUA_PATHSEP,

                              LUA_PATHSEP AUXMARK LUA_PATHSEP);

    luaL_gsub(L, path, AUXMARK, def);

    lua_remove(L, -2);

  }

  setprogdir(L);

  lua_setfield(L, -2, fieldname);

}

static const luaL_Reg pk_funcs[] = {

  {"loadlib", ll_loadlib},

  {"seeall", ll_seeall},

  {NULL, NULL}

};

static const luaL_Reg ll_funcs[] = {

  {"module", ll_module},

  {"require", ll_require},

  {NULL, NULL}

};

static const lua_CFunction loaders[] =

  {loader_preload, loader_Lua, loader_C, loader_Croot, NULL};

LUALIB_API int luaopen_package (lua_State *L) {

  int i;

  /* create new type _LOADLIB */

  luaL_newmetatable(L, "_LOADLIB");

  lua_pushcfunction(L, gctm);

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

  /* create `package' table */

  luaL_register(L, LUA_LOADLIBNAME, pk_funcs);

#if defined(LUA_COMPAT_LOADLIB) 

  lua_getfield(L, -1, "loadlib");

  lua_setfield(L, LUA_GLOBALSINDEX, "loadlib");

#endif

  lua_pushvalue(L, -1);

  lua_replace(L, LUA_ENVIRONINDEX);

  /* create `loaders' table */

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

  /* fill it with pre-defined loaders */

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

    lua_pushcfunction(L, loaders[i]);

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

  }

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

  setpath(L, "path", LUA_PATH, LUA_PATH_DEFAULT);  /* set field `path' */

  setpath(L, "cpath", LUA_CPATH, LUA_CPATH_DEFAULT); /* set field `cpath' */

  /* store config information */

  lua_pushstring(L, LUA_DIRSEP "\n" LUA_PATHSEP "\n" LUA_PATH_MARK "\n"

                    LUA_EXECDIR "\n" LUA_IGMARK);

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

  /* set field `loaded' */

  luaL_findtable(L, LUA_REGISTRYINDEX, "_LOADED", 2);

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

  /* set field `preload' */

  lua_newtable(L);

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

  lua_pushvalue(L, LUA_GLOBALSINDEX);

  luaL_register(L, NULL, ll_funcs);  /* open lib into global table */

  lua_pop(L, 1);

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

}