virsh: Deal with multiple matching devices in domif-getlink

The command tries to match interface in domain definition by MAC
address or interface name. However, since it's possible to
configure two interfaces with the same MAC address, it may
happen that the XPath returns two or more nodes. We should check
for that.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

tools/virsh-domain-monitor.c

@@ -707,13 +707,16 @@ cmdDomIfGetLink(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;
     }
 
-    if (ninterfaces != 1) {
+    if (ninterfaces < 1) {
         if (macstr[0])
             vshError(ctl, _("Interface (mac: %s) not found."), macstr);
         else
             vshError(ctl, _("Interface (dev: %s) not found."), iface);
 
         goto cleanup;
+    } else if (ninterfaces > 1) {
+        vshError(ctl, _("multiple matching interfaces found"));
+        goto cleanup;
     }
 
     ctxt->node = interfaces[0];