From 2c24456389d6518d0d429c0c4f41e5bf52c2d793 Mon Sep 17 00:00:00 2001
From: Antoine Cellerier <dionoea@videolan.org>
Date: Fri, 26 Feb 2010 11:56:32 +0100
Subject: [PATCH] Do not store p_this in a table value visible from lua code.

---
 modules/misc/lua/demux.c              |  3 +--
 modules/misc/lua/extension.c          |  5 ++---
 modules/misc/lua/intf.c               |  6 ++----
 modules/misc/lua/libs/misc.c          | 16 +++++++++++-----
 modules/misc/lua/meta.c               |  5 ++---
 modules/misc/lua/services_discovery.c |  3 +--
 modules/misc/lua/vlc.h                |  2 ++
 7 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/modules/misc/lua/demux.c b/modules/misc/lua/demux.c
index 601287f058..c3d3595c69 100644
--- a/modules/misc/lua/demux.c
+++ b/modules/misc/lua/demux.c
@@ -135,14 +135,13 @@ static int probe_luascript( vlc_object_t *p_this, const char * psz_filename,
     /* Load Lua libraries */
     luaL_openlibs( L ); /* FIXME: Don't open all the libs? */
 
+    vlclua_set_this( L, p_demux );
     luaL_register( L, "vlc", p_reg );
     luaopen_msg( L );
     luaopen_strings( L );
     luaopen_stream( L );
     luaopen_xml( L );
     luaopen_md5( L );
-    lua_pushlightuserdata( L, p_demux );
-    lua_setfield( L, -2, "private" );
     lua_pushstring( L, p_demux->psz_path );
     lua_setfield( L, -2, "path" );
     lua_pushstring( L, p_demux->psz_access );
diff --git a/modules/misc/lua/extension.c b/modules/misc/lua/extension.c
index a6fa103359..174d18dda1 100644
--- a/modules/misc/lua/extension.c
+++ b/modules/misc/lua/extension.c
@@ -719,13 +719,12 @@ static lua_State* GetLuaState( extensions_manager_t *p_mgr,
             msg_Err( p_mgr, "Could not create new Lua State" );
             return NULL;
         }
+        vlclua_set_this( L, p_mgr );
+
         luaL_openlibs( L );
         luaL_register( L, "vlc", p_reg );
         luaopen_msg( L );
 
-        lua_pushlightuserdata( L, p_mgr );
-        lua_setfield( L, -2, "private" );
-
         lua_pushlightuserdata( L, p_ext );
         lua_setfield( L, -2, "extension" );
 
diff --git a/modules/misc/lua/intf.c b/modules/misc/lua/intf.c
index 90bb782005..3415907616 100644
--- a/modules/misc/lua/intf.c
+++ b/modules/misc/lua/intf.c
@@ -168,15 +168,13 @@ int Open_LuaIntf( vlc_object_t *p_this )
         goto error;
     }
 
+    vlclua_set_this( L, p_intf );
+
     luaL_openlibs( L );
 
     /* register our functions */
     luaL_register( L, "vlc", p_reg );
 
-    /* store a pointer to p_intf (FIXME: user could overwrite this) */
-    lua_pushlightuserdata( L, p_intf );
-    lua_setfield( L, -2, "private" );
-
     /* register submodules */
     luaopen_acl( L );
     luaopen_config( L );
diff --git a/modules/misc/lua/libs/misc.c b/modules/misc/lua/libs/misc.c
index 5e5e8060e6..444092dada 100644
--- a/modules/misc/lua/libs/misc.c
+++ b/modules/misc/lua/libs/misc.c
@@ -50,13 +50,19 @@
 /*****************************************************************************
  * Internal lua<->vlc utils
  *****************************************************************************/
+void __vlclua_set_this( lua_State *L, vlc_object_t *p_this )
+{
+    lua_pushlightuserdata( L, __vlclua_set_this );
+    lua_pushlightuserdata( L, p_this );
+    lua_rawset( L, LUA_REGISTRYINDEX );
+}
+
 vlc_object_t * vlclua_get_this( lua_State *L )
 {
-    vlc_object_t * p_this;
-    lua_getglobal( L, "vlc" );
-    lua_getfield( L, -1, "private" );
-    p_this = (vlc_object_t*)lua_topointer( L, lua_gettop( L ) );
-    lua_pop( L, 2 );
+    lua_pushlightuserdata( L, __vlclua_set_this );
+    lua_rawget( L, LUA_REGISTRYINDEX );
+    vlc_object_t *p_this = (vlc_object_t*)lua_topointer( L, -1 );
+    lua_pop( L, 1 );
     return p_this;
 }
 
diff --git a/modules/misc/lua/meta.c b/modules/misc/lua/meta.c
index b61ec4ec6a..a56fd091d2 100644
--- a/modules/misc/lua/meta.c
+++ b/modules/misc/lua/meta.c
@@ -60,6 +60,8 @@ static lua_State * init( vlc_object_t *p_this, input_item_t * p_item, const char
         return NULL;
     }
 
+    vlclua_set_this( L, p_this );
+
     /* Load Lua libraries */
     luaL_openlibs( L ); /* XXX: Don't open all the libs? */
 
@@ -75,9 +77,6 @@ static lua_State * init( vlc_object_t *p_this, input_item_t * p_item, const char
     luaopen_md5( L );
     luaopen_input_item( L, p_item );
 
-    lua_pushlightuserdata( L, p_this );
-    lua_setfield( L, -2, "private" );
-
     if( vlclua_add_modules_path( p_this, L, psz_filename ) )
     {
         msg_Warn( p_this, "Error while setting the module search path for %s",
diff --git a/modules/misc/lua/services_discovery.c b/modules/misc/lua/services_discovery.c
index f5e21fdff7..d5f36494da 100644
--- a/modules/misc/lua/services_discovery.c
+++ b/modules/misc/lua/services_discovery.c
@@ -94,10 +94,9 @@ int Open_LuaSD( vlc_object_t *p_this )
         msg_Err( p_sd, "Could not create new Lua State" );
         goto error;
     }
+    vlclua_set_this( L, p_sd );
     luaL_openlibs( L );
     luaL_register( L, "vlc", p_reg );
-    lua_pushlightuserdata( L, p_sd );
-    lua_setfield( L, -2, "private" );
     luaopen_input( L );
     luaopen_msg( L );
     luaopen_misc( L );
diff --git a/modules/misc/lua/vlc.h b/modules/misc/lua/vlc.h
index e6e13d2ca8..20b19fd500 100644
--- a/modules/misc/lua/vlc.h
+++ b/modules/misc/lua/vlc.h
@@ -91,6 +91,8 @@ static inline const char *luaL_nilorcheckstring( lua_State *L, int narg )
     return luaL_checkstring( L, narg );
 }
 
+#define vlclua_set_this(a, b) __vlclua_set_this(a, VLC_OBJECT(b))
+void __vlclua_set_this( lua_State *, vlc_object_t * );
 vlc_object_t * vlclua_get_this( lua_State * );
 
 /*****************************************************************************
-- 
2.39.2