Add the LuaBlock

README.md

@@ -22,6 +22,7 @@ MoreMesecons is a mod for minetest which adds some mesecons items.
 * `Igniter` : This node is a lighter that ignites its adjacent flammable nodes (including TNT).
 * `Injector Controller` : This node is useful to activate/deactivate a pipeworks filter injector : it sends a blinky signal.
 * `Jammer` : If turned on, this node stops mesecons in a radius of 10 nodes.
+* `LuaBlock`: This block allows its owner to execute any Lua code in the global environment when turned on. Using it requires the server privilege.
 * `Luacontroller Template Tool` : This tool is very useful to manipulate templates with luacontrollers. Just click with it on a luacontroller, then you'll see a formspec.
 * `Player Killer` : This block kills the nearest player (with a maximal distance of 8 blocks by default) (if this player isn't its owner) when it receives a mesecons signal.
 * `Sayer` : This node sends a message to every players inside a radius of 8 nodes.

moremesecons_luablock/depends.txt

@@ -0,0 +1 @@
+mesecons

moremesecons_luablock/init.lua

@@ -0,0 +1,113 @@
+local function make_formspec(meta, pos)
+	local code = meta:get_string("code")
+	local errmsg = minetest.formspec_escape(meta:get_string("errmsg"))
+	meta:set_string("formspec",
+		"size[10,8;]" ..
+		"textarea[0.5,0.5;10,7;code;Code;"..code.."]" ..
+		"label[0.1,7;"..errmsg.."]" ..
+		"button_exit[4,7.5;2,1;submit;Submit]")
+end
+
+minetest.register_node("moremesecons_luablock:luablock", {
+	description = "Lua Block",
+	tiles =  {"moremesecons_luablock.png"},
+	groups = {cracky = 2},
+	on_place = function(itemstack, placer, pointed_thing)
+		local under = pointed_thing.under
+		local node = minetest.get_node(under)
+		local udef = minetest.registered_nodes[node.name]
+		if udef and udef.on_rightclick and
+				not (placer and placer:get_player_control().sneak) then
+			return udef.on_rightclick(under, node, placer, itemstack,
+				pointed_thing) or itemstack
+		end
+
+		local pos
+		if minetest.registered_items[minetest.get_node(under).name].buildable_to then
+			pos = under
+		else
+			pos = pointed_thing.above
+		end
+
+		local name = placer:get_player_name()
+		if minetest.is_protected(pos, name) and
+				not minetest.check_player_privs(name, {protection_bypass = true}) then
+			minetest.record_protection_violation(pos, name)
+			return itemstack
+		end
+		if not minetest.check_player_privs(name, {server = true}) then
+			minetest.chat_send_player(name, "You can't use a LuaBlock without the server privilege.")
+			return itemstack
+		end
+
+		local node_def = minetest.registered_nodes[minetest.get_node(pos).name]
+		if not node_def or not node_def.buildable_to then
+			return itemstack
+		end
+
+		minetest.set_node(pos, {name = "moremesecons_luablock:luablock"})
+
+		local meta = minetest.get_meta(pos)
+		meta:set_string("owner", name)
+		meta:set_string("infotext", "LuaBlock owned by " .. name)
+		make_formspec(meta, pos)
+
+		if not (creative and creative.is_enabled_for
+				and creative.is_enabled_for(placer:get_player_name())) then
+			itemstack:take_item()
+		end
+		return itemstack
+	end,
+	on_receive_fields = function(pos, form_name, fields, sender)
+		if not fields.submit then
+			return
+		end
+		local name = sender:get_player_name()
+		local meta = minetest.get_meta(pos)
+		if name ~= meta:get_string("owner") then
+			minetest.chat_send_player(name, "You don't own this LuaBlock.")
+			return
+		end
+		if not minetest.check_player_privs(name, {server = true}) then
+			minetest.chat_send_player(name, "You can't use a LuaBlock without the server privilege.")
+			return
+		end
+
+		meta:set_string("code", fields.code)
+		make_formspec(meta, pos)
+	end,
+	can_dig = function(pos, player)
+		local meta = minetest.get_meta(pos)
+		return meta:get_string("owner") == player:get_player_name()
+	end,
+	mesecons = {effector = {
+		action_on = function(pos, node)
+			local meta = minetest.get_meta(pos)
+			local code = meta:get_string("code")
+			if code == "" then
+				return
+			end
+			-- We do absolutely no check there.
+			-- There is no limitation in the number of instruction the LuaBlock can execute
+			-- or the usage it can make of loops.
+			-- It is executed in the global namespace.
+			-- Remember: *The LuaBlock is highly dangerous and should be manipulated cautiously!*
+			local func, err = loadstring(code)
+			if not func then
+				meta:set_string("errmsg", err)
+				make_formspec(meta, pos)
+				return
+			end
+			local good, err = pcall(func)
+			-- Still alive! No shutdown requested? No infinite loop?
+			if not good then -- Runtime error
+				meta:set_string("errmsg", err)
+				make_formspec(meta, pos)
+				return
+			end
+
+			meta:set_string("errmsg", "")
+			make_formspec(meta, pos)
+		end
+	}}
+})