mod security compatibility

exchange.lua

@@ -1,5 +1,6 @@
 
-local sql = require("lsqlite3")
+local insecure_env = ...
+local sql = insecure_env.require("lsqlite3")
 local exports = {}
 
 local init_query = [=[

init.lua

@@ -1,16 +1,19 @@
 
+local insecure_env = minetest.request_insecure_environment()
+assert(insecure_env,
+	"global_exchange needs to be trusted to run under mod security.")
+
 local modpath = minetest.get_modpath(minetest.get_current_modname()) .. "/"
 
 local income = tonumber(minetest.setting_get("citizens_income")) or 10
-
 local income_interval = 1200
-
 local income_msg = "You receive your citizen's income (+" .. income .. ")"
 
 local next_payout = os.time() + income_interval
 
-local exchange = (dofile(modpath .. "exchange.lua")).open_exchange(
-	minetest.get_worldpath() .. "/global_exchange.db"
+local exchange =
+        assert(loadfile(modpath .. "exchange.lua"))(insecure_env).open_exchange(
+		minetest.get_worldpath() .. "/global_exchange.db"
 )