fix(mgmt): Ensure the CLI will not create useless atom

The log level, the log handler id and the listener id  all of them already exist,
so it's better to avoid the user create a useless atom by mistake input

apps/emqx_management/src/emqx_mgmt_cli.erl

@@ -356,15 +356,26 @@ mnesia(_) ->
 %% @doc Logger Command
 
 log(["set-level", Level]) ->
-    case emqx_logger:set_log_level(list_to_atom(Level)) of
-        ok -> emqx_ctl:print("~ts~n", [Level]);
-        Error -> emqx_ctl:print("[error] set overall log level failed: ~p~n", [Error])
+    case emqx_misc:safe_to_existing_atom(Level) of
+        {ok, Level1} ->
+            case emqx_logger:set_log_level(Level1) of
+                ok -> emqx_ctl:print("~ts~n", [Level]);
+                Error -> emqx_ctl:print("[error] set overall log level failed: ~p~n", [Error])
+            end;
+        _ ->
+            emqx_ctl:print("[error] invalid level: ~p~n", [Level])
     end;
 log(["primary-level"]) ->
     Level = emqx_logger:get_primary_log_level(),
     emqx_ctl:print("~ts~n", [Level]);
 log(["primary-level", Level]) ->
-    _ = emqx_logger:set_primary_log_level(list_to_atom(Level)),
+    case emqx_misc:safe_to_existing_atom(Level) of
+        {ok, Level1} ->
+            _ = emqx_logger:set_primary_log_level(Level1),
+            ok;
+        _ ->
+            emqx_ctl:print("[error] invalid level: ~p~n", [Level])
+    end,
     emqx_ctl:print("~ts~n", [emqx_logger:get_primary_log_level()]);
 log(["handlers", "list"]) ->
     _ = [
@@ -381,26 +392,50 @@ log(["handlers", "list"]) ->
     ],
     ok;
 log(["handlers", "start", HandlerId]) ->
-    case emqx_logger:start_log_handler(list_to_atom(HandlerId)) of
-        ok ->
-            emqx_ctl:print("log handler ~ts started~n", [HandlerId]);
-        {error, Reason} ->
-            emqx_ctl:print("[error] failed to start log handler ~ts: ~p~n", [HandlerId, Reason])
+    case emqx_misc:safe_to_existing_atom(HandlerId) of
+        {ok, HandlerId1} ->
+            case emqx_logger:start_log_handler(HandlerId1) of
+                ok ->
+                    emqx_ctl:print("log handler ~ts started~n", [HandlerId]);
+                {error, Reason} ->
+                    emqx_ctl:print("[error] failed to start log handler ~ts: ~p~n", [
+                        HandlerId, Reason
+                    ])
+            end;
+        _ ->
+            emqx_ctl:print("[error] invalid handler:~ts~n", [HandlerId])
     end;
 log(["handlers", "stop", HandlerId]) ->
-    case emqx_logger:stop_log_handler(list_to_atom(HandlerId)) of
-        ok ->
-            emqx_ctl:print("log handler ~ts stopped~n", [HandlerId]);
-        {error, Reason} ->
-            emqx_ctl:print("[error] failed to stop log handler ~ts: ~p~n", [HandlerId, Reason])
+    case emqx_misc:safe_to_existing_atom(HandlerId) of
+        {ok, HandlerId1} ->
+            case emqx_logger:stop_log_handler(HandlerId1) of
+                ok ->
+                    emqx_ctl:print("log handler ~ts stopped~n", [HandlerId1]);
+                {error, Reason} ->
+                    emqx_ctl:print("[error] failed to stop log handler ~ts: ~p~n", [
+                        HandlerId1, Reason
+                    ])
+            end;
+        _ ->
+            emqx_ctl:print("[error] invalid handler:~ts~n", [HandlerId])
     end;
 log(["handlers", "set-level", HandlerId, Level]) ->
-    case emqx_logger:set_log_handler_level(list_to_atom(HandlerId), list_to_atom(Level)) of
-        ok ->
-            #{level := NewLevel} = emqx_logger:get_log_handler(list_to_atom(HandlerId)),
-            emqx_ctl:print("~ts~n", [NewLevel]);
-        {error, Error} ->
-            emqx_ctl:print("[error] ~p~n", [Error])
+    case emqx_misc:safe_to_existing_atom(HandlerId) of
+        {ok, HandlerId1} ->
+            case emqx_misc:safe_to_existing_atom(Level) of
+                {ok, Level1} ->
+                    case emqx_logger:set_log_handler_level(HandlerId1, Level1) of
+                        ok ->
+                            #{level := NewLevel} = emqx_logger:get_log_handler(HandlerId1),
+                            emqx_ctl:print("~ts~n", [NewLevel]);
+                        {error, Error} ->
+                            emqx_ctl:print("[error] ~p~n", [Error])
+                    end;
+                _ ->
+                    emqx_ctl:print("[error] invalid level:~p~n", [Level])
+            end;
+        _ ->
+            emqx_ctl:print("[error] invalid handler:~ts~n", [HandlerId])
     end;
 log(_) ->
     emqx_ctl:usage(
@@ -593,25 +628,40 @@ listeners([]) ->
         emqx_listeners:list()
     );
 listeners(["stop", ListenerId]) ->
-    case emqx_listeners:stop_listener(list_to_atom(ListenerId)) of
-        ok ->
-            emqx_ctl:print("Stop ~ts listener successfully.~n", [ListenerId]);
-        {error, Error} ->
-            emqx_ctl:print("Failed to stop ~ts listener: ~0p~n", [ListenerId, Error])
+    case emqx_misc:safe_to_existing_atom(ListenerId) of
+        {ok, ListenerId1} ->
+            case emqx_listeners:stop_listener(ListenerId1) of
+                ok ->
+                    emqx_ctl:print("Stop ~ts listener successfully.~n", [ListenerId]);
+                {error, Error} ->
+                    emqx_ctl:print("Failed to stop ~ts listener: ~0p~n", [ListenerId, Error])
+            end;
+        _ ->
+            emqx_ctl:print("Invalid listener: ~0p~n", [ListenerId])
     end;
 listeners(["start", ListenerId]) ->
-    case emqx_listeners:start_listener(list_to_atom(ListenerId)) of
-        ok ->
-            emqx_ctl:print("Started ~ts listener successfully.~n", [ListenerId]);
-        {error, Error} ->
-            emqx_ctl:print("Failed to start ~ts listener: ~0p~n", [ListenerId, Error])
+    case emqx_misc:safe_to_existing_atom(ListenerId) of
+        {ok, ListenerId1} ->
+            case emqx_listeners:start_listener(ListenerId1) of
+                ok ->
+                    emqx_ctl:print("Started ~ts listener successfully.~n", [ListenerId]);
+                {error, Error} ->
+                    emqx_ctl:print("Failed to start ~ts listener: ~0p~n", [ListenerId, Error])
+            end;
+        _ ->
+            emqx_ctl:print("Invalid listener: ~0p~n", [ListenerId])
     end;
 listeners(["restart", ListenerId]) ->
-    case emqx_listeners:restart_listener(list_to_atom(ListenerId)) of
-        ok ->
-            emqx_ctl:print("Restarted ~ts listener successfully.~n", [ListenerId]);
-        {error, Error} ->
-            emqx_ctl:print("Failed to restart ~ts listener: ~0p~n", [ListenerId, Error])
+    case emqx_misc:safe_to_existing_atom(ListenerId) of
+        {ok, ListenerId1} ->
+            case emqx_listeners:restart_listener(ListenerId1) of
+                ok ->
+                    emqx_ctl:print("Restarted ~ts listener successfully.~n", [ListenerId]);
+                {error, Error} ->
+                    emqx_ctl:print("Failed to restart ~ts listener: ~0p~n", [ListenerId, Error])
+            end;
+        _ ->
+            emqx_ctl:print("Invalid listener: ~0p~n", [ListenerId])
     end;
 listeners(_) ->
     emqx_ctl:usage([