varlink: if varlink_call() is called with ret_error_id=NULL propagate error via retur...

It's OK if callers don't want to know the varlink error string. But in
that case return the fact the call failed via the return value, as a
negative errno as usual, to make sure it's not accidentally ignored.

Similar for varlink_observe()

diff --git a/src/shared/varlink.c b/src/shared/varlink.c
index ce9cf736468099de9f55f5cac14d6b391c9abf96..d39db5382d643f9dd88a4eaecc936ce3510eb7b9 100644 (file)
--- a/src/shared/varlink.c
+++ b/src/shared/varlink.c
@@ -2211,21 +2211,29 @@ int varlink_call(
 
         switch (v->state) {
 
-        case VARLINK_CALLED:
+        case VARLINK_CALLED: {
                 assert(v->current);
 
                 varlink_set_state(v, VARLINK_IDLE_CLIENT);
                 assert(v->n_pending == 1);
                 v->n_pending--;
 
+                JsonVariant *e = json_variant_by_key(v->current, "error"),
+                        *p = json_variant_by_key(v->current, "parameters");
+
+                /* If caller doesn't ask for the error string, then let's return an error code in case of failure */
+                if (!ret_error_id && e)
+                        return varlink_error_to_errno(json_variant_string(e), p);
+
                 if (ret_parameters)
-                        *ret_parameters = json_variant_by_key(v->current, "parameters");
+                        *ret_parameters = p;
                 if (ret_error_id)
-                        *ret_error_id = json_variant_string(json_variant_by_key(v->current, "error"));
+                        *ret_error_id = e ? json_variant_string(e) : NULL;
                 if (ret_flags)
                         *ret_flags = 0;
 
                 return 1;
+        }
 
         case VARLINK_PENDING_DISCONNECT:
         case VARLINK_DISCONNECTED:
@@ -2341,6 +2349,11 @@ int varlink_collect(
 
                 /* If we get an error from any of the replies, return immediately with just the error_id and flags*/
                 if (context.error_id) {
+
+                        /* If caller doesn't ask for the error string, then let's return an error code in case of failure */
+                        if (!ret_error_id)
+                                return varlink_error_to_errno(context.error_id, context.parameters);
+
                         if (ret_parameters)
                                 *ret_parameters = TAKE_PTR(context.parameters);
                         if (ret_error_id)
@@ -2374,6 +2387,9 @@ int varlink_collect(
                 assert_not_reached();
         }
 
+        if (!ret_error_id && context.error_id)
+                return varlink_error_to_errno(context.error_id, context.parameters);
+
         if (ret_parameters)
                 *ret_parameters = TAKE_PTR(context.parameters);
         if (ret_error_id)