object_add: consolidate error handling

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
vl.c: -object: don't ignore duplicate 'id'

object_property_add_child() may fail if 'id' matches
an already existing object. Which means an incorrect
command line.
So instead of silently ignoring error, report it and
terminate QEMU.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
add optional 2nd stage initialization to -object/object-add commands

Introduces USER_CREATABLE interface that must be implemented by
objects which are designed to created with -object CLI option or
object-add QMP command.

Interface provides an ability to do an optional second stage
initialization of the object created with -object/object-add
commands. By providing complete() callback, which is called
after the object properties were set.

It allows to:
 * prevents misusing of -object/object-add by filtering out
   objects that are not designed for it.
 * generalize second stage backend initialization instead of
   adding custom APIs to perform it
 * early error detection of backend initialization at -object/
   object-add time rather than through a proxy DEVICE object
   that tries to use backend.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
virtio_rng: replace custom backend API with UserCreatable.complete() callback

in addition fix default backend leak by releasing it if its
initialization failed.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
monitor: Cleanup mon->outbuf on write error

In case monitor_flush() fails to write the contents of mon->outbuf to
the output device, mon->outbuf is not cleaned up properly. Check the
return code of the qemu_chr_fe_write() function and cleanup the outbuf
if it fails.

References: http://lists.nongnu.org/archive/html/qemu-devel/2014-01/msg02890.html

Signed-off-by: Stratos Psomadakis <psomas@grnet.gr>
Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Merge remote-tracking branch 'qmp-unstable/queue/qmp' into staging

* qmp-unstable/queue/qmp:
  monitor: Cleanup mon->outbuf on write error
  virtio_rng: replace custom backend API with UserCreatable.complete() callback
  add optional 2nd stage initialization to -object/object-add commands
  vl.c: -object: don't ignore duplicate 'id'
  object_add: consolidate error handling

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Merge branch 'master' of git://git.qemu.org/qemu