Improve RX functions

src/netif.ml

@@ -31,7 +31,7 @@ external uk_bigarray_of_netbuf : int64 -> bytes_array = "uk_bigarray_of_netbuf"
 external uk_netdev_tx : int64 -> int64 -> int -> (unit, string) result
   = "uk_netdev_tx"
 
-external uk_netdev_rx : int64 -> Cstruct.buffer -> int -> bool * int * string
+external uk_netdev_rx : int64 -> Cstruct.buffer -> int -> (int, string) result
   = "uk_netdev_rx"
 
 open Lwt.Infix
@@ -121,19 +121,21 @@ let rec read t buf =
     else
       (* TODO what about offset? *)
       match uk_netdev_rx t.netif buf.Cstruct.buffer buf.Cstruct.len with
-      | true, 0, _ -> Lwt.return (Error `Continue)
-      | true, size, _ ->
+      | Ok 0 -> Lwt.return (Error `Continue)
+      | Ok size ->
           Mirage_net.Stats.rx t.stats (Int64.of_int size);
           let buf = Cstruct.sub buf 0 size in
           Lwt.return (Ok buf)
-      | false, _, err -> Lwt.return (Error `Disconnected)
+      | Error msg ->
+          Log.err (fun f -> f "Error receiving: %s" msg);
+          Lwt.return (Error `Unspecified_error)
   in
   process () >>= function
   | Error `Continue ->
       Unikraft_os.Main.UkEngine.wait_for_work_netdev t.id >>= fun () ->
       read t buf
   | Error `Canceled -> Lwt.return (Error `Canceled)
-  | Error `Disconnected -> Lwt.return (Error `Disconnected)
+  | Error `Unspecified_error -> Lwt.return (Error `Disconnected)
   | Ok buf -> Lwt.return (Ok buf)
 
 (* Loop and listen for packets permanently *)

src/rx.c

@@ -98,23 +98,17 @@ static int netdev_rx(struct netif* netif, uint8_t *buf, unsigned *size,
 CAMLprim value uk_netdev_rx(value v_netif, value v_buf, value v_size)
 {
   CAMLparam3(v_netif, v_buf, v_size);
-  CAMLlocal2(v_result, v_error);
+  CAMLlocal1(v_result);
 
   struct netif *netif = (struct netif*)Int64_val(v_netif);
   uint8_t *buf = (uint8_t *)Caml_ba_data_val(v_buf);
   unsigned size = Int_val(v_size);
-
-  v_result = caml_alloc_tuple(3);
-  Store_field(v_result, 0, Val_false);
-  Store_field(v_result, 1, Val_int(0));
-  Store_field(v_result, 2, caml_copy_string(""));
-
   const char *err = NULL;
+
   const int rc = netdev_rx(netif, buf, &size, &err);
   if (rc < 0) {
     uk_pr_err("netdev_rx: failed with %s\n", err);
-    v_error = caml_copy_string(err);
-    Store_field(v_result, 2, v_error);
+    v_result = alloc_result_error(err);
     CAMLreturn(v_result);
   }
 
@@ -125,9 +119,9 @@ CAMLprim value uk_netdev_rx(value v_netif, value v_buf, value v_size)
     set_netdev_queue_empty(netif->id);
   }
 
-  Store_field(v_result, 0, Val_true);
-  Store_field(v_result, 1, Val_int(size));
-
   uk_pr_debug("uk_netdev_rx: read %d bytes\n", size);
+
+  v_result = alloc_result_ok();
+  Store_field(v_result, 0, Val_int(size));
   CAMLreturn(v_result);
 }