From 63d0d602c794a531b94b0e7bf87337ef96ce6ba5 Mon Sep 17 00:00:00 2001
From: prestidigitator <prestidigitator@dev.minetest.net>
Date: Fri, 4 Jul 2014 16:59:31 -0700
Subject: [PATCH] Added player-local context and /luaclear command

---
 PlayerEnv.lua | 66 +++++++++++++++++++++++++++++++++++++++++
 README.txt    | 14 ++++++++-
 init.lua      | 81 +++++++++++++++++++++++++--------------------------
 3 files changed, 119 insertions(+), 42 deletions(-)
 create mode 100644 PlayerEnv.lua

diff --git a/PlayerEnv.lua b/PlayerEnv.lua
new file mode 100644
index 0000000..21169ca
--- /dev/null
+++ b/PlayerEnv.lua
@@ -0,0 +1,66 @@
+local PrintablePos =
+{
+   __tostring = function(pos)
+      return "(" .. pos.x .. ", " .. pos.y .. ", " .. pos.z .. ")";
+   end
+};
+function PrintablePos:new(pos)
+   return setmetatable(pos, self);
+end
+
+local PlayerEnv =
+{
+   playerContexts = setmetatable({}, { __mode = "k" }),  -- weak keys
+
+   playerFuncs =
+      {
+         me = function(player)
+            return player;
+         end,
+
+         myname = function(player)
+            return player:get_player_name();
+         end,
+
+         here = function(player)
+            return PrintablePos:new(player:getpos());
+         end,
+
+         print = function(player)
+            return function(...)
+               local str = "";
+               for _, arg in ipairs({...}) do
+                  str = str .. tostring(arg);
+               end
+               minetest.chat_send_player(player:get_player_name(), str, false);
+            end
+         end
+      };
+};
+
+function PlayerEnv:new(player)
+   local env = {};
+   self.playerContexts[env] = player;
+   setmetatable(env, self);
+   return env;
+end
+setmetatable(PlayerEnv, { __call = PlayerEnv.new });
+
+function PlayerEnv.__index(env, key)
+   local playerFunc = PlayerEnv.playerFuncs[key];
+   if playerFunc then
+      local player = PlayerEnv.playerContexts[env];
+      return playerFunc(player);
+   else
+      return _G[key];
+   end
+end
+
+function PlayerEnv.__newindex(env, key, value)
+   if PlayerEnv.playerFuncs[key] then
+      error("cannot set special '"..key.."' player variable");
+   end
+   rawset(env, key, value);
+end
+
+return PlayerEnv;
diff --git a/README.txt b/README.txt
index e42ca2c..5528001 100644
--- a/README.txt
+++ b/README.txt
@@ -36,7 +36,9 @@ Required Minetest Version: (tested in 0.4.9)
 
 Dependencies: (none)
 
-Commands: /lua <luaStatement>
+Commands:
+   * /lua <luaStatement>
+   * /luaclear
 
 Privileges: lua
 
@@ -64,6 +66,16 @@ Try the following commands:
    /lua print(myname);
    /lua print(here);
 
+Version 1.2
+
+* Release 2014-07-04
+* Keeps "global" variables set by commands in a player-local context.
+* Prevents setting of special variables (e.g. me, myname, here, print).
+* Added /luaclear command to clear the player-local context.
+
+To set true globals visible to mods and other players, use "_G.var = ...".  Can
+also be used to get any globals hidden by specials and player-local variables.
+
 Copyright and Licensing
 -----------------------
 
diff --git a/init.lua b/init.lua
index f95a043..73f7a66 100644
--- a/init.lua
+++ b/init.lua
@@ -1,16 +1,30 @@
-local function copyTable(t)
-   if type(t) ~= "table" then return t; end
-   local tc = {};
-   for k, v in pairs(t) do
-      tc[k] = v;
-   end
-   return tc;
-end
+local MOD_NAME = minetest.get_current_modname();
+local MOD_PATH = minetest.get_modpath(MOD_NAME);
 
-local function posToStr(pos)
-   return "(" .. pos.x .. ", " ..pos.y.. ", " .. pos.z .. ")";
+local PlayerEnv = dofile(MOD_PATH.."/PlayerEnv.lua");
+
+local playerEnvs = {};
+minetest.register_on_leaveplayer(
+   function(player)
+      playerEnvs[player:get_player_name()] = nil;
+   end);
+
+local function runLuaCmd(playerName, paramStr)
+   local cmdFunc, errMsg = loadstring(paramStr, "/lua command");
+   if not cmdFunc then
+      error(errMsg);
+   end
+
+   local playerEnv = playerEnvs[playerName];
+   if not playerEnv then
+      local player = minetest.get_player_by_name(playerName);
+      playerEnv = PlayerEnv:new(player);
+      playerEnvs[playerName] = playerEnv;
+   end
+
+   setfenv(cmdFunc, playerEnv);
+   cmdFunc();
 end
-local posMeta = { __tostring = posToStr };
 
 minetest.register_privilege(
    "lua",
@@ -26,37 +40,22 @@ minetest.register_chatcommand(
       description = "Executes a lua statement (chunk), for debugging.",
       privs = { lua = true },
       func =
-         function(name, param)
-            local cmdFunc, success, errMsg;
-
-            cmdFunc, errMsg = loadstring(param, "/lua command");
-            if not cmdFunc then
-               minetest.chat_send_player(name, "ERROR: "..errMsg);
-               return;
-            end
-
-            local player = minetest.get_player_by_name(name);
-            local pos = player:getpos();
-            setmetatable(pos, posMeta);
-
-            local env = copyTable(getfenv(0));
-            env.print =
-               function(...)
-                  str = "";
-                  for _, arg in ipairs({...}) do
-                     str = str .. tostring(arg);
-                  end
-                  minetest.chat_send_player(name, str, false);
-               end;
-            env.myname = name;
-            env.me = player;
-            env.here = pos;
-
-            setfenv(cmdFunc, env);
-
-            success, errMsg = pcall(cmdFunc);
+         function(playerName, paramStr)
+            local success, errMsg = pcall(runLuaCmd, playerName, paramStr);
             if not success then
-               minetest.chat_send_player(name, "ERROR: "..errMsg);
+               minetest.chat_send_player(playerName, "ERROR: "..errMsg);
             end
          end
    });
+
+minetest.register_chatcommand(
+   "luaclear",
+   {
+      params = "",
+      description = "Clears all variables in your /lua player context",
+      privs = { lua = true },
+      func =
+         function(playerName, paramStr)
+            playerEnvs[playerName] = nil;
+         end
+   });