lua/loadlib.c

/*
** $Id: loadlib.c,v 1.6 2004/04/30 20:13:38 roberto Exp roberto $
** Dynamic library loader for Lua
** 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.
*/

#define loadlib_c
#define LUA_LIB

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


#undef LOADLIB


#ifdef USE_DLOPEN
#define LOADLIB
/*
* 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 int loadlib(lua_State *L)
{
 const char *path=luaL_checkstring(L,1);
 const char *init=luaL_checkstring(L,2);
 void *lib=dlopen(path,RTLD_NOW);
 if (lib!=NULL)
 {
  lua_CFunction f=(lua_CFunction) dlsym(lib,init);
  if (f!=NULL)
  {
   lua_pushlightuserdata(L,lib);
   lua_pushcclosure(L,f,1);
   return 1;
  }
 }
 /* else return appropriate error messages */
 lua_pushnil(L);
 lua_pushstring(L,dlerror());
 lua_pushstring(L,(lib!=NULL) ? "init" : "open");
 if (lib!=NULL) dlclose(lib);
 return 3;
}

#endif



/*
** In Windows, default is to use dll; otherwise, default is not to use dll
*/
#ifndef USE_DLL
#ifdef _WIN32
#define USE_DLL	1
#else
#define USE_DLL	0
#endif
#endif


#if USE_DLL
#define LOADLIB
/*
* This is an implementation of loadlib for Windows using native functions.
*/

#include <windows.h>

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);
}

static int loadlib(lua_State *L)
{
 const char *path=luaL_checkstring(L,1);
 const char *init=luaL_checkstring(L,2);
 HINSTANCE lib=LoadLibrary(path);
 if (lib!=NULL)
 {
  lua_CFunction f=(lua_CFunction) GetProcAddress(lib,init);
  if (f!=NULL)
  {
   lua_pushlightuserdata(L,lib);
   lua_pushcclosure(L,f,1);
   return 1;
  }
 }
 lua_pushnil(L);
 pusherror(L);
 lua_pushstring(L,(lib!=NULL) ? "init" : "open");
 if (lib!=NULL) FreeLibrary(lib);
 return 3;
}

#endif

/* Native Mac OS X / Darwin Implementation */
#ifdef USE_DYLD
#define LOADLIB

#include <mach-o/dyld.h>

static int loadlib (lua_State *L) {
  const char * err_str;
  const char * err_file;
  NSLinkEditErrors err;
  int err_num;
  const char *path=luaL_checkstring(L,1);
  const char *init=luaL_checkstring(L,2);
  const struct mach_header *lib;
  /* this would be a rare case, but prevents crashing if it happens */
  if(!_dyld_present()) {
    lua_pushnil(L);
    lua_pushstring(L,"dyld not present.");
    lua_pushstring(L,"absent");
    return 3;
  }

  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);
      lua_pushlightuserdata(L,(void *)lib);
      lua_pushcclosure(L,f,1);
      return 1;
    }
  }
  /* else an error ocurred */
  NSLinkEditError(&err, &err_num, &err_file, &err_str);
  lua_pushnil(L);
  lua_pushstring(L, err_str);
  lua_pushstring(L, (lib != NULL) ? "init" : "open");
  /* Can't unload image */
  return 3;
}

#endif



#ifndef LOADLIB
/* Fallback for other systems */

/*
** Those systems support dlopen, so they should have defined USE_DLOPEN.
** The default (no)implementation gives them a special error message.
*/
#if defined(linux) || defined(sun) || defined(sgi) || defined(BSD) || defined(_WIN32)
#define LOADLIB	"`loadlib' not installed (check your Lua configuration)"
#else
#define LOADLIB	"`loadlib' not supported"
#endif


static int loadlib(lua_State *L)
{
 lua_pushnil(L);
 lua_pushliteral(L,LOADLIB);
 lua_pushliteral(L,"absent");
 return 3;
}
#endif

LUALIB_API int luaopen_loadlib (lua_State *L)
{
 lua_register(L,"loadlib",loadlib);
 return 0;
}

/*
* 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.
*
* 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
*
* Mac OS X/Darwin
* http://www.opendarwin.org/projects/dlcompat/
*
* GLIB has wrapper code for BeOS, OS2, Unix and Windows
* http://cvs.gnome.org/lxr/source/glib/gmodule/
*
*/