Add unittest that lints builtin JSON files

games/devtest/mods/unittests/misc.lua

@@ -189,6 +189,29 @@ local function test_write_json()
 end
 unittests.register("test_write_json", test_write_json)
 
+local function lint_json_files()
+	-- Check that files we ship with Luanti are valid JSON
+	local stack = {core.get_builtin_path()}
+	local checked = 0
+	while #stack > 0 do
+		local path = table.remove(stack)
+		for _, name in ipairs(core.get_dir_list(path, true)) do
+			stack[#stack+1] = path .. "/" .. name
+		end
+		for _, name in ipairs(core.get_dir_list(path, false)) do
+			if name:match("%.json$") then
+				local f = io.open(path .. "/" .. name, "rb")
+				print(path .. "/" .. name)
+				assert(core.parse_json(f:read("*all"), -1) ~= nil)
+				f:close()
+				checked = checked + 1
+			end
+		end
+	end
+	assert(checked > 0, "no files found?!")
+end
+unittests.register("lint_json_files", lint_json_files)
+
 local function test_game_info()
 	local info = core.get_game_info()
 	local game_conf = Settings(info.path .. "/game.conf")

src/script/cpp_api/s_security.cpp

@@ -659,6 +659,13 @@ bool ScriptApiSecurity::checkPathWithGamedef(lua_State *L,
 		}
 	}
 
+	// Allow read-only access to builtin
+	if (!write_required) {
+		str = fs::AbsolutePath(Server::getBuiltinLuaPath());
+		if (!str.empty() && fs::PathStartsWith(abs_path, str))
+			return true;
+	}
+
 	// Allow read-only access to game directory
 	if (!write_required) {
 		const SubgameSpec *game_spec = gamedef->getGameSpec();