Epic/mods/tpad/storage.lua

local storage = minetest.get_mod_storage()

function tpad._get_all_pads()
   local storage_table = storage:to_table()
   local allpads = {}
   for key, value in pairs(storage_table.fields) do
      local parts = key:split(":")
      if parts[1] == "pads" then
         local pads = minetest.deserialize(value)
         if type(pads) == "table" then
            if parts[2] then
               allpads[parts[2]] = pads
            end
         end
      end
   end
   return allpads
end

function tpad._get_stored_pads(ownername)
   local serial_pads = storage:get_string("pads:" .. ownername)
   if serial_pads == nil or serial_pads == "" then return {} end
   return minetest.deserialize(serial_pads)
end

function tpad._set_stored_pads(ownername, pads)
   storage:set_string("pads:" .. ownername, minetest.serialize(pads))
end

function tpad.set_max_total_pads(max)
   if not max then max = 0 end
   storage:set_string("max_total_pads_per_player", max)
end

function tpad.get_max_total_pads()
   local max = tonumber(storage:get_string("max_total_pads_per_player"))
   if not max then
      tpad.set_max_total_pads(100)
      return 100
   end
   return max
end

function tpad.set_max_global_pads(max)
   if not max then max = 0 end
   storage:set_string("max_global_pads_per_player", max)
end

function tpad.get_max_global_pads()
   local max = tonumber(storage:get_string("max_global_pads_per_player"))
   if not max then
      tpad.set_max_global_pads(4)
      return 4
   end
   return max
end

local function _convert_legacy_settings()
   local legacy_settings_file = minetest.get_worldpath() .. "/mod_storage/" .. tpad.mod_name .. ".custom.conf"
   local file = io.open(legacy_settings_file, "r")
   if file then
      file:close()
      local settings = Settings(legacy_settings_file)
      local max_global = tonumber(settings:get("max_global_pads_per_player"))
      if max_global then
         tpad.set_max_global_pads(max_global)
      end
      local max_total = tonumber(settings:get("max_total_pads_per_player"))
      if max_total then
         tpad.set_max_total_pads(max_total)
      end
      os.remove(legacy_settings_file)
   end
end

_convert_legacy_settings()
tpad.get_max_total_pads()
tpad.get_max_global_pads()

local function _convert_storage_1_1()
   local storage_table = storage:to_table()
   for field, value in pairs(storage_table.fields) do
      local parts = field:split(":")
      if parts[1] == "pads" then
         local pads = minetest.deserialize(value)
         for key, name in pairs(pads) do
            pads[key] = { name = name }
         end
         storage_table.fields[field] = minetest.serialize(pads)
      end
   end
   storage:from_table(storage_table)
end

local function _storage_version_check()
   local storage_version = storage:get_string("_version")
   local storage_path = minetest.get_worldpath() .. "/mod_storage/"
   if storage_version == "1.1" then
      local file = io.open(storage_path .. tpad.mod_name, "r")
      if file then
         file:close()
         tpad._copy_file(storage_path .. tpad.mod_name, storage_path .. tpad.mod_name .. ".1.1.backup")
      end
      _convert_storage_1_1()
   elseif storage_version ~= "" and storage_version ~= tpad.version then
      error("Mod storage version not supported, aborting to prevent data corruption")
   end
   storage:set_string("_version", tpad.version)
end

_storage_version_check()