commit ca2b20c7665e6ee1d6f966e9a7c8bd43ac45c245
Author: Gaël de Sailly <gael-de-sailly@netc.eu>
Date:   Thu Feb 21 17:35:41 2019 +0100

    Initial commit
    Allows to enable/disable placement of certain nodes on world layers

diff --git a/api.lua b/api.lua
new file mode 100644
index 0000000..6e90450
--- /dev/null
+++ b/api.lua
@@ -0,0 +1,70 @@
+worldlayers = {}
+
+local layers = {} -- localize to make use simpler and faster in the code
+worldlayers.registered_layers = layers
+
+function worldlayers.register_layer(layer)
+	local size = layer.ymax - layer.ymin
+	for i, old_layer in ipairs(layers) do
+		if old_layer.ymax - old_layer.ymin > size then
+			table.insert(layers, i, layer)
+			return
+		end
+	end
+	table.insert(layers, layer)
+end
+
+function worldlayers.iter(pos)
+	local y = pos.y
+	local n = 1
+	return function()
+		for i=n, #layers do
+			local layer = layers[i]
+			if y >= layer.ymin and y <= layer.ymax then
+				n = i+1
+				return i, layer
+			end
+		end
+	end
+end
+
+function worldlayers.is_action_allowed(pos, node, action)
+	for _, layer in worldlayers.iter(pos) do
+		local restriction_table = layer.restrictions
+		if restriction_table then
+			local restriction = restriction_table[action]
+			if type(restriction) == "table" then
+				if restriction[node] ~= nil then
+					return restriction[node]
+				elseif restriction.general ~= nil then
+					return restriction.general
+				end
+			elseif type(restriction) == "boolean" then
+				return restriction
+			end
+		end
+	end
+	return true
+end
+
+local old_is_protected = minetest.is_protected
+function minetest.is_protected(pos, name)
+	local old_node = minetest.get_node(pos).name
+	local node, action
+	if old_node ~= "air" then
+		node = old_node
+		action = "dig"
+	else
+		local player = minetest.get_player_by_name(name)
+		if not player then
+			return false
+		end
+		local new_node = player:get_wielded_item():get_name()
+		if node ~= "" then
+			node = new_node
+			action = "place"
+		end
+	end
+	local is_protected = not worldlayers.is_action_allowed(pos, node, action)
+	return is_protected or old_is_protected(pos, name)
+end
diff --git a/init.lua b/init.lua
new file mode 100644
index 0000000..33ab272
--- /dev/null
+++ b/init.lua
@@ -0,0 +1,13 @@
+local modpath = minetest.get_modpath("worldlayers")
+dofile(modpath .. "/api.lua")
+
+worldlayers.register_layer({
+	ymin = -31000,
+	ymax = -100,
+	restrictions = {
+		place = {
+			["default:chest"] = false,
+			["default:chest_locked"] = false,
+		},
+	},
+})