lua/loadlib.c

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/*
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** $Id: loadlib.c,v 1.12 2004/12/13 12:14:21 roberto Exp roberto $
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** Dynamic library loader for Lua
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** See Copyright Notice in lua.h
*
* This Lua library exports a single function, called loadlib, which
* is called from Lua as loadlib(lib,init), where lib is the full
* name of the library to be loaded (including the complete path) and
* init is the name of a function to be called after the library is
* loaded. Typically, this function will register other functions, thus
* making the complete library available to Lua. The init function is
* *not* automatically called by loadlib. Instead, loadlib returns the
* init function as a Lua function that the client can call when it
* thinks is appropriate. In the case of errors, loadlib returns nil and
* two strings describing the error. The first string is supplied by
* the operating system; it should be informative and useful for error
* messages. The second string is "open", "init", or "absent" to identify
* the error and is meant to be used for making decisions without having
* to look into the first string (whose format is system-dependent).
* 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. See
* the list at the end of this file for some links to available
* implementations of dlfcn and interfaces to other native dynamic
* loaders on top of which loadlib could be implemented.
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*/
#include <stdlib.h>
#include <string.h>
#define loadlib_c
#define LUA_LIB
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#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
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#define ERR_OPEN 1
#define ERR_FUNCTION 2
#define ERR_ABSENT 3
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static void registerlib (lua_State *L, const void *lib);
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#if defined(USE_DLOPEN)
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/*
* 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>
#define freelib dlclose
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static int loadlib(lua_State *L, const char *path, const char *init) {
void *lib=dlopen(path,RTLD_NOW);
if (lib != NULL) {
lua_CFunction f=(lua_CFunction) dlsym(lib,init);
if (f != NULL) {
registerlib(L, lib);
lua_pushcfunction(L,f);
return 0;
}
}
/* else return appropriate error message */
lua_pushstring(L,dlerror());
if (lib != NULL) {
dlclose(lib);
return ERR_FUNCTION; /* error loading function */
}
else return ERR_OPEN; /* error loading library */
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}
#elif defined(USE_DLL)
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/*
* This is an implementation of loadlib for Windows using native functions.
*/
#include <windows.h>
#define freelib(lib) FreeLibrary((HINSTANCE)lib)
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static void pusherror(lua_State *L) {
int error = GetLastError();
char buffer[128];
if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,
0, error, 0, buffer, sizeof(buffer), 0))
lua_pushstring(L,buffer);
else
lua_pushfstring(L, "system error %d\n", error);
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}
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static int loadlib (lua_State *L, const char *path, const char *init) {
HINSTANCE lib = LoadLibrary(path);
if (lib != NULL) {
lua_CFunction f = (lua_CFunction)GetProcAddress(lib, init);
if (f != NULL) {
registerlib(L, lib);
lua_pushcfunction(L, f);
return 0;
}
}
pusherror(L);
if (lib != NULL) {
FreeLibrary(lib);
return ERR_OPEN;
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}
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else return ERR_FUNCTION;
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}
/* Native Mac OS X / Darwin Implementation */
#elif defined(USE_DYLD)
#include <mach-o/dyld.h>
/* Mach cannot unload images (?) */
#define freelib(lib) ((void)lib)
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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);
}
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static int loadlib (lua_State *L, const char *path, const char *init) {
const struct mach_header *lib;
/* this would be a rare case, but prevents crashing if it happens */
if(!_dyld_present()) {
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lua_pushstring(L, "dyld not present.");
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return ERR_OPEN;
}
lib = NSAddImage(path, NSADDIMAGE_OPTION_RETURN_ON_ERROR);
if(lib != NULL) {
NSSymbol init_sym = NSLookupSymbolInImage(lib, init,
NSLOOKUPSYMBOLINIMAGE_OPTION_BIND |
NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR);
if(init_sym != NULL) {
lua_CFunction f = (lua_CFunction)NSAddressOfSymbol(init_sym);
registerlib(L, lib);
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lua_pushcfunction(L, f);
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return 0;
}
}
/* else an error ocurred */
pusherror(L);
/* Can't unload image */
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return (lib != NULL) ? ERR_FUNCTION : ERR_OPEN;
}
#else
/* Fallback for other systems */
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#define freelib(lib) ((void)lib)
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static int loadlib (lua_State *L, const char *path, const char *init) {
(void)path; (void)init; (void)&registerlib; /* to avoid warnings */
lua_pushliteral(L,"`loadlib' not supported");
return ERR_ABSENT;
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}
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#endif
/*
** common code for all implementations: put a library into the registry
** so that, when Lua closes its state, the library's __gc metamethod
** will be called to unload the library.
*/
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static void registerlib (lua_State *L, const void *lib) {
const void **plib = (const void **)lua_newuserdata(L, sizeof(const void *));
*plib = lib;
luaL_getmetatable(L, "_LOADLIB");
lua_setmetatable(L, -2);
lua_pushboolean(L, 1);
lua_settable(L, LUA_REGISTRYINDEX); /* registry[lib] = true */
}
/*
** __gc tag method: calls library's `freelib' function with the lib
** handle
*/
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static int gctm (lua_State *L) {
void *lib = *(void **)luaL_checkudata(L, 1, "_LOADLIB");
freelib(lib);
return 0;
}
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static int ll_loadlib (lua_State *L) {
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static const char *const errcodes[] = {NULL, "open", "init", "absent"};
const char *path = luaL_checkstring(L, 1);
const char *init = luaL_checkstring(L, 2);
int res = loadlib(L,path,init);
if (res == 0) /* no error? */
return 1; /* function is at stack top */
else { /* error */
lua_pushnil(L);
lua_insert(L, -2); /* insert nil before error message */
lua_pushstring(L, errcodes[res]);
return 3;
}
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}
/*
** {======================================================
** `require' and `module' functions
** =======================================================
*/
static const char *loadLua (lua_State *L, const char *fname, const char *name) {
const char *path;
/* try first `LUA_PATH' for compatibility */
lua_getglobal(L, "LUA_PATH");
path = lua_tostring(L, -1);
if (!path) {
lua_pop(L, 1);
luaL_getfield(L, LUA_GLOBALSINDEX, "package.path");
path = lua_tostring(L, -1);
}
if (path == NULL)
luaL_error(L, "`package.path' must be a string");
fname = luaL_searchpath(L, fname, path);
if (fname == NULL) return path; /* library not found in this path */
if (luaL_loadfile(L, fname) != 0)
luaL_error(L, "error loading package `%s' (%s)", name, lua_tostring(L, -1));
return NULL; /* library loaded successfully */
}
static const char *loadC (lua_State *L, const char *fname, const char *name) {
const char *path;
const char *funcname;
luaL_getfield(L, LUA_GLOBALSINDEX, "package.cpath");
path = lua_tostring(L, -1);
if (path == NULL)
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luaL_error(L, "`package.cpath' must be a string");
fname = luaL_searchpath(L, fname, path);
if (fname == NULL) return path; /* library not found in this path */
funcname = luaL_gsub(L, name, ".", LUA_OFSEP);
funcname = lua_pushfstring(L, "%s%s", LUA_POF, funcname);
if (loadlib(L, fname, funcname) != 0)
luaL_error(L, "error loading package `%s' (%s)", name, lua_tostring(L, -1));
return NULL; /* library loaded successfully */
}
static int ll_require (lua_State *L) {
const char *name = luaL_checkstring(L, 1);
lua_settop(L, 1);
lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
lua_getfield(L, 2, name);
if (lua_toboolean(L, -1)) /* is it there? */
return 1; /* package is already loaded; return its result */
/* else must load it; first mark it as loaded */
lua_pushboolean(L, 1);
lua_setfield(L, 2, name); /* _LOADED[name] = true */
/* check whether it is preloaded */
lua_getfield(L, LUA_REGISTRYINDEX, "_PRELOAD");
lua_getfield(L, -1, name);
if (lua_isnil(L, -1)) { /* no preload function for that module? */
const char *fname = luaL_gsub(L, name, ".", LUA_DIRSEP);
const char *cpath = loadC(L, fname, name); /* try a C module */
if (cpath) { /* not found? */
const char *path = loadLua(L, fname, name); /* try a Lua module */
if (path) { /* yet not found? */
lua_pushnil(L);
lua_setfield(L, 2, name); /* unmark _LOADED[name] */
return luaL_error(L, "package `%s' not found\n"
" cpath: %s\n path: %s",
name, cpath, path);
}
}
}
lua_pushvalue(L, 1); /* 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); /* update _LOADED[name] with returned value */
lua_getfield(L, 2, name); /* return _LOADED[name] */
return 1;
}
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);
}
static int ll_module (lua_State *L) {
const char *modname = luaL_checkstring(L, 1);
const char *dot;
lua_settop(L, 1);
lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
/* try to find given table */
luaL_getfield(L, LUA_GLOBALSINDEX, modname);
if (lua_isnil(L, -1)) { /* not found? */
lua_pop(L, 1); /* remove previous result */
lua_newtable(L); /* create it */
/* register it with given name */
lua_pushvalue(L, -1);
luaL_setfield(L, LUA_GLOBALSINDEX, modname);
}
else if (!lua_istable(L, -1))
return luaL_error(L, "name conflict for module `%s'", modname);
/* 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);
lua_newtable(L); /* create new metatable */
lua_pushvalue(L, LUA_GLOBALSINDEX);
lua_setfield(L, -2, "__index"); /* mt.__index = _G */
lua_setmetatable(L, -2);
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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");
}
lua_pushvalue(L, -1);
lua_setfield(L, 2, modname); /* _LOADED[modname] = new table */
setfenv(L);
return 0;
}
/* }====================================================== */
static const luaL_reg ll_funcs[] = {
{"loadlib", ll_loadlib},
{"require", ll_require},
{"module", ll_module},
{NULL, NULL}
};
LUALIB_API int luaopen_loadlib (lua_State *L) {
const char *path;
/* create new type _LOADLIB */
luaL_newmetatable(L, "_LOADLIB");
lua_pushcfunction(L, gctm);
lua_setfield(L, -2, "__gc");
/* create `package' table */
lua_newtable(L);
lua_pushvalue(L, -1);
lua_setglobal(L, "package");
/* set field `path' */
path = getenv(LUA_PATH);
if (path == NULL) path = LUA_PATH_DEFAULT;
lua_pushstring(L, path);
lua_setfield(L, -2, "path");
/* set field `cpath' */
path = getenv(LUA_CPATH);
if (path == NULL) path = LUA_CPATH_DEFAULT;
lua_pushstring(L, path);
lua_setfield(L, -2, "cpath");
/* set field `loaded' */
lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
lua_setfield(L, -2, "loaded");
/* set field `preload' */
lua_getfield(L, LUA_REGISTRYINDEX, "_PRELOAD");
lua_setfield(L, -2, "preload");
lua_pushvalue(L, LUA_GLOBALSINDEX);
luaL_openlib(L, NULL, ll_funcs, 0); /* open lib into global table */
return 1;
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}
/*
* Here are some links to available implementations of dlfcn and
* interfaces to other native dynamic loaders on top of which loadlib
* could be implemented. Please send contributions and corrections to us.
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*
* AIX
* Starting with AIX 4.2, dlfcn is included in the base OS.
* There is also an emulation package available.
* http://www.faqs.org/faqs/aix-faq/part4/section-21.html
*
* HPUX
* HPUX 11 has dlfcn. For HPUX 10 use shl_*.
* http://www.geda.seul.org/mailinglist/geda-dev37/msg00094.html
* http://www.stat.umn.edu/~luke/xls/projects/dlbasics/dlbasics.html
*
* Macintosh, Windows
* http://www.stat.umn.edu/~luke/xls/projects/dlbasics/dlbasics.html
*
* GLIB has wrapper code for BeOS, OS2, Unix and Windows
* http://cvs.gnome.org/lxr/source/glib/gmodule/
*
*/