first version of `loadlib'

2 files changed, 177 insertions, 1 deletions

diff --git a/loadlib.c b/loadlib.c
new file mode 100644
index 00000000..69b1339e
--- /dev/null
+++ b/loadlib.c
@@ -0,0 +1,173 @@
+/*
+** $Id$
+** Bare-bones 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 bare-bones loadlib  function is supposed to be used  as a foundation
+* for  more sophisticated  dynamic library  loaders, possibly  still called
+* loadlib and probably written in Lua, that  will be smart enough to try to
+* find the library in different directories and also perhaps guess the name
+* of the init function.
+*
+* This module contains  an implementation of loadlib for  Unix systems that
+* have dlfcn, 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.
+*
+*/
+
+#include "lua.h"
+#include "lauxlib.h"
+#include "lualib.h"
+
+#ifndef USE_LOADLIB
+#define USE_LOADLIB 1
+#endif
+
+#ifndef USE_DLOPEN
+#define USE_DLOPEN 0
+#endif
+
+#if USE_LOADLIB
+
+#if defined(linux) || defined(sun) || defined(sgi) || defined(BSD) || 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;
+  }
+ }
+ lua_pushnil(L);
+ lua_pushstring(L,dlerror());
+ lua_pushstring(L,(lib!=NULL) ? "init" : "open");
+ if (lib!=NULL) dlclose(lib);
+ return 3;
+}
+
+#elif defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
+#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("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;
+}
+
+#else
+/*
+* write an implementation for your system  here and send it to us, together
+* with preprocessing symbols that identify your system.
+*/
+#endif
+#endif
+
+#ifndef LOADLIB
+/* Fallback for other systems */
+
+static int loadlib(lua_State *L)
+{
+ lua_pushnil(L);
+ lua_pushliteral(L,"`loadlib' not supported");
+ 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  por  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/
+*
+*/
diff --git a/lualib.h b/lualib.h
index d393b66d..23e64fce 100644
--- a/lualib.h
+++ b/lualib.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lualib.h,v 1.25 2002/07/09 18:49:13 roberto Exp roberto $
+** $Id: lualib.h,v 1.26 2003/03/11 12:24:34 roberto Exp roberto $
 ** Lua standard libraries
 ** See Copyright Notice in lua.h
 */
@@ -36,6 +36,9 @@ LUALIB_API int luaopen_math (lua_State *L);
 LUALIB_API int luaopen_debug (lua_State *L);
 
 
+LUALIB_API int luaopen_loadlib (lua_State *L);
+
+
 /* to help testing the libraries */
 #ifndef lua_assert
 #define lua_assert(c)           /* empty */