Use protection to make a worldborder

mods/mcljepc_core/blocks.lua

@@ -38,7 +38,8 @@ minetest.register_craftitem("mcljepc_core:block", {
 			nodename = "mcljepc_core:grass"
 		end
 
-		minetest.set_node(pointed_thing.above, { name = nodename })
+		-- Unlike set node, this actually checks against protection
+		minetest.item_place(ItemStack(nodename), user, pointed_thing)
 	end,
 	on_drop = function(itemstack, dropper, pos)
 		return itemstack

mods/mcljepc_fakeworldborder/init.lua

@@ -0,0 +1,14 @@
+local ymax = 21
+local ymin = mcljepc_mapgen.depth * -1
+local zmax = mcljepc_mapgen.size
+local zmin = mcljepc_mapgen.size * -1
+local xmax = mcljepc_mapgen.size
+local xmin = mcljepc_mapgen.size * -1
+local old_is_protected = minetest.is_protected
+function minetest.is_protected(pos, name)
+	return old_is_protected(pos, name) or not (
+		    ymin < pos.y and pos.y < ymax
+		and zmin < pos.z and pos.z < zmax
+		and xmin < pos.x and pos.x < xmax
+	)
+end

mods/mcljepc_fakeworldborder/mod.conf

@@ -0,0 +1,2 @@
+name = mcljepc_fakeworldborder
+depends = mcljepc_mapgen,mcljepc_core