vnc: fix "info vnc" with "-vnc ..., reverse=on"

When reverse connection is in use, there is no active VNC server
socket.  Because of this, getsockopt(-1, ...) is attempted and
the following error is emitted:

    $ socat TCP-LISTEN:5900,reuseaddr TCP-LISTEN:5901,reuseaddr &
    $ x86_64-softmmu/qemu-system-x86_64 -vnc localhost:5900,reverse -monitor stdio
    QEMU 1.2.50 monitor - type 'help' for more information
    (qemu) info vnc
    An undefined error has occurred

Because however the host, family, service and auth fields are
optional, we can just exit if there is no active server socket.

    $ x86_64-softmmu/qemu-system-x86_64 -vnc localhost:5900,reverse -monitor stdio
    QEMU 1.2.50 monitor - type 'help' for more information
    (qemu) info vnc
    Server:
    Client:
         address: 127.0.0.1:5900
      x509_dname: none
        username: none

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 417b0b88904fe1dd8c41bff8092dfbab0134d9cb)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/ui/vnc.c b/ui/vnc.c
index 18ec101115acc9e2038bcc733ec4ae5b12115e6f..66ae93010fae4bb78db2ba7dcaf55f474230dd56 100644 (file)
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -372,6 +372,10 @@ VncInfo *qmp_query_vnc(Error **errp)
             }
         }
 
+        if (vnc_display->lsock == -1) {
+            return info;
+        }
+
         if (getsockname(vnc_display->lsock, (struct sockaddr *)&sa,
                         &salen) == -1) {
             error_set(errp, QERR_UNDEFINED_ERROR);