Store script's LuaListener in userdata in lua_State's Registry.

Instead of deriving LuaListener from LLInstanceTracker with an int key,
generating a unique int key and storing that key in the Registry, use new
lua_emplace<LuaState>() to store the LuaListener directly in a Lua userdata
object in the Lua Registry.

Because lua_emplace<T>() uses LL.atexit() to guarantee that ~LuaState will
destroy the T object, we no longer need ~LuaState() to make a special call
specifically to destroy the LuaListener, if any. So we no longer need
LuaState::getListener() separate from obtainListener().

Since LuaListener is no longer an LLInstanceTracker subclass, make
LuaState::obtainListener() return LuaListener& rather than LuaListener::ptr_t.

1 files changed, 2 insertions, 18 deletions

diff --git a/indra/llcommon/lualistener.h b/indra/llcommon/lualistener.h
index 85fb093cd6..68131dfa27 100644
--- a/indra/llcommon/lualistener.h
+++ b/indra/llcommon/lualistener.h
@@ -12,8 +12,7 @@
 #if ! defined(LL_LUALISTENER_H)
 #define LL_LUALISTENER_H
 
-#include "llevents.h"
-#include "llinstancetracker.h"
+#include "llevents.h"               // LLTempBoundListener
 #include "llsd.h"
 #include "llthreadsafequeue.h"
 #include <iosfwd>                   // std::ostream
@@ -27,25 +26,11 @@ class LLLeapListener;
 /**
  * LuaListener is based on LLLeap. It serves an analogous function.
  *
- * Each LuaListener instance has an int key, generated randomly to
- * inconvenience malicious Lua scripts wanting to mess with others. The idea
- * is that a given lua_State stores in its Registry:
- * - "event.listener": the int key of the corresponding LuaListener, if any
- * The original thought was that LuaListener would itself store the Lua
- * function -- but surprisingly, there is no C/C++ type in the API that stores
- * a Lua function.
- *
- * (We considered storing in "event.listener" the LuaListener pointer itself
- * as a light userdata, but the problem would be if Lua code overwrote that.
- * We want to prevent any Lua script from crashing the viewer, intentionally
- * or otherwise. Safer to use a key lookup.)
- *
  * Like LLLeap, each LuaListener instance also has an associated
  * LLLeapListener to respond to LLEventPump management commands.
  */
-class LuaListener: public LLInstanceTracker<LuaListener, int>
+class LuaListener
 {
-    using super = LLInstanceTracker<LuaListener, int>;
 public:
     LuaListener(lua_State* L);
 
@@ -68,7 +53,6 @@ public:
     friend std::ostream& operator<<(std::ostream& out, const LuaListener& self);
 
 private:
-    static int getUniqueKey();
     bool queueEvent(const std::string& pump, const LLSD& data);
 
     LLThreadSafeQueue<PumpData> mQueue;