Let core.get_mod_storage be called multiple times (#12572)

builtin/client/init.lua

@@ -5,6 +5,7 @@ local commonpath = scriptpath.."common"..DIR_DELIM
 
 dofile(clientpath .. "register.lua")
 dofile(commonpath .. "after.lua")
+dofile(commonpath .. "mod_storage.lua")
 dofile(commonpath .. "chatcommands.lua")
 dofile(clientpath .. "chatcommands.lua")
 dofile(clientpath .. "death_formspec.lua")

builtin/common/mod_storage.lua

@@ -0,0 +1,19 @@
+-- Modify core.get_mod_storage to return the storage for the current mod.
+
+local get_current_modname = core.get_current_modname
+
+local old_get_mod_storage = core.get_mod_storage
+
+local storages = setmetatable({}, {
+	__mode = "v", -- values are weak references (can be garbage-collected)
+	__index = function(self, modname)
+		local storage = old_get_mod_storage(modname)
+		self[modname] = storage
+		return storage
+	end,
+})
+
+function core.get_mod_storage()
+	local modname = get_current_modname()
+	return modname and storages[modname]
+end

builtin/game/init.lua

@@ -17,6 +17,7 @@ if core.settings:get_bool("profiler.load") then
 end
 
 dofile(commonpath .. "after.lua")
+dofile(commonpath .. "mod_storage.lua")
 dofile(gamepath .. "item_entity.lua")
 dofile(gamepath .. "deprecated.lua")
 dofile(gamepath .. "misc_s.lua")

src/script/lua_api/l_storage.cpp

@@ -25,12 +25,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 int ModApiStorage::l_get_mod_storage(lua_State *L)
 {
-	lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
+	// Note that this is wrapped in Lua, see builtin/common/mod_storage.lua
-	if (!lua_isstring(L, -1)) {
+	std::string mod_name = readParam<std::string>(L, 1);
-		return 0;
-	}
-
-	std::string mod_name = readParam<std::string>(L, -1);
 
 	ModMetadata *store = nullptr;