ubus: allow object method call handlers to return a numeric status code

The implicit return style for sending ubus method replies currently always
emits an UBUS_STATUS_NO_DATA code in case neither req.reply() was called,
nor a deferred or object were returned by the handler function.

This slightly complicates the implementation of handlers that do not wish
to send reply data but simply acknowledge the request with an
UBUS_STATUS_OK code.

In order to simplify this use case, allow handlers to override the default
status by treating integer return values as ubus error codes.

After this change, the following handler:

    function (request) {
        /* do some work */

        request.reply(null, 0);
    }

... can be rewritten as:

    function (request) {
        /* do some work */

        return 0;
    }

Suggested-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 10 insertions, 1 deletions

diff --git a/lib/ubus.c b/lib/ubus.c
index 4766119..e2491ec 100644
--- a/lib/ubus.c
+++ b/lib/ubus.c
@@ -1226,7 +1226,16 @@ uc_ubus_handle_reply_common(struct ubus_context *ctx,
 		 * returned and if reqobj.reply() hasn't been called, immediately
 		 * finish deferred request with UBUS_STATUS_NO_DATA. */
 		else if (!callctx->replied) {
-			ubus_complete_deferred_request(ctx, &callctx->req, UBUS_STATUS_NO_DATA);
+			rv = UBUS_STATUS_NO_DATA;
+
+			if (ucv_type(res) == UC_INTEGER) {
+				rv = (int)ucv_int64_get(res);
+
+				if (rv < 0 || rv > __UBUS_STATUS_LAST)
+					rv = UBUS_STATUS_UNKNOWN_ERROR;
+			}
+
+			ubus_complete_deferred_request(ctx, &callctx->req, rv);
 			callctx->replied = true;
 		}