net: Improve error message for -net hubport a bit

Type "hubport" is valid only with -netdev.  Unfortunately, that's
detected late and the error message doesn't explain why:

    $ qemu-system-i386 -net hubport,id=foo,hubid=0
    qemu-system-i386: -net hubport,id=foo,hubid=0: Device 'hubport' could not be initialized

Improve the error message to "Parameter 'type' expects a net type".

Not fixed: -net hubport without the parameters required by -netdev
hubport still asks for those parameters:

    $ qemu-system-i386 -net hubport
    qemu-system-i386: -net hubport: Parameter 'hubid' is missing

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1431691143-1015-2-git-send-email-armbru@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/net.c b/net/net.c
index 7427f6a65a..d9aaeb5341 100644
--- a/net/net.c
+++ b/net/net.c
@@ -882,6 +882,11 @@ static int net_client_init1(const void *object, int is_netdev, Error **errp)
     } else {
         u.net = object;
         opts = u.net->opts;
+        if (opts->kind == NET_CLIENT_OPTIONS_KIND_HUBPORT) {
+            error_set(errp, QERR_INVALID_PARAMETER_VALUE, "type",
+                      "a net type");
+            return -1;
+        }
         /* missing optional values have been initialized to "all bits zero" */
         name = u.net->has_id ? u.net->id : u.net->name;
     }