Minetest-WorldEdit/worldedit_protection/init.lua

--if there's no protection mod, no worldedit means no editing, worldedit means editing anywhere (old behaviour)
--if there's a protection mod, no worldedit means editing only in your area, worldedit means editing in no-man's land too, areas means editing anywhere.

--let the other mod load first
minetest.after(0, function()
	--I would use mod.soft_depend from commonlib, but there are multiple mods that could create owned land
	PROTECTION_MOD_EXISTS = minetest.is_protected == old_is_protected
	--else fall back to old behaviour, where
	--worldedit privilege is permission to edit everything
end)

--I wanted this function to directly choose the privileges for the chat command, but it only applies once.
--privs={worldedit=true             [, server=true]}
--privs={worldedit=worldedit.priv() [, server=true]}
--instead, I had to wrap the rest of func = .
worldedit.privs = function(func)
	--this silly syntax was copied from safe_region, which is actually executed on chatcommand registration, and must return a function instead of the result of a function.
	--The innermost anonymous function is declared. Then safe_region executes, adding a function wrapper around that function. Then worldedit.privs gets that as an argument, and adds another wrapper. The doubly-wrapped function is the one registered as a chatcommand.
	return function(name, param)
		if not minetest.setting_getbool("creative_mode") or not PROTECTION_MOD_EXISTS then
			--no protection mod, or not the kind of world where people can just create nodes out of thin air,
			--worldedit privilege means editing anywhere
			if minetest.check_player_privs(name, {worldedit=true}) then
				func(name, param)
			else
				return
			end
		else
			--protection mod, can edit inside your area without worldedit privilege
			--(worldedit and areas let you edit in no-man's land and other-owned area)
			func(name, param)
		end
	end
end

--this is... within chatcommands that actually change land
--(should be the same functions as safe_region)
--also check for permission when region is set? no, //stack goes outside the boundaries.
--so the region is defined per-command on exec.
worldedit.can_edit_volume = function(name, pos1, pos2) --, func?
	--old you-can-worldedit-everything behaviour.
	if not PROTECTION_MOD_EXISTS or minetest.check_player_privs(name, {areas=true}) then
		--If there's no mod, worldedit.privs already required that you have the worldedit privilege,then if you were able to run this command, then you have the worldedit privilege.
		--Or, you can set areas, so you are allowed to worldedit them too. The ability to set the whole world as owned by yourself is already potentially destructive, what's more destructive capability?
		return true
	end
	--new ownership-based behaviour

	--[[I need to use a special per-command region (think /stack, or even worse, /move), the same one safe_region uses, but corner points instead of count... instead of a for loop interpolating between pos1 and pos2]]--

	--all-or-nothing here
	--local pos1, pos2 = worldedit.pos1[name], worldedit.pos2[name]
	pos1, pos2 = worldedit.sort_pos(pos1, pos2) --does this matter?
	for i in area:iterp(pos1, pos2) do
--[[
		THIS SECTION IGNORES the distinction of area that is owned by someone else, but still editable
		this is treated as area owned by the editor, or no-man's land depending on if it's shared with one person or everyone

		If it was treated differently (it's not), then single edits would not be able to cross the border between someone else's editable land, and no-man's land, to prevent accidental writes. It may cross the border between multiple people's editable land (or should it?), such as to create a bridge between two skyscrapers that were previously built separately.

		This needs testing for the other changes first.
--]]
		--Is it owned?
		if minetest.is_protected(i) then
			--Is it someone else's?
			if minetest.is_protected(i, name) then
				--already checked the ability to make it mine (areas)
				minetest.chat_send_player(name, "Someone else owns at least part of what you want to edit")
				return false
			end
			--it's mine
			--continue

		--no-man's land
		--can I edit that?
		elseif not minetest.check_player_privs(name, {worldedit=true}) then --cache this check?
			minetest.chat_send_player(name, "You can only edit area in which you own a plot (missing worldedit privilege)")
			return false
		end
	end

	--the whole thing is
	--a) owned by me,
	--b) owned by no one and I have the worldedit privilege, and/or
	--c) I have the areas privilege and it's possibly owned by someone else.
	return true
end