>
> Hi,
>
> On Tue, Aug 20, 2019 at 04:05:46PM +0200, Jakub Janků wrote:
> > If the task is cancelled, g_task_propagate_pointer()
> > in spice_vmc_output_stream_write_finish() returns NULL
> > which produces following errors:
> >
> > (spicy:13597): GSpice-CRITICAL **: 15:39:46.168:
> > spice_vmc_write_finish: assertion 'result != NULL' failed
> >
> > (spicy:13597): GLib-GObject-CRITICAL **: 15:39:46.168: g_object_unref:
> > assertion 'G_IS_OBJECT (object)' failed
>
> What I found weird was actually that we do _ref() on write_cb()
> but this got cleanup anyway, seems like a bug somewhere.
>
It's not a bug, as Jakub said and from g_task_propagate_pointer
documentation "If the task resulted in an error, or was cancelled,
then this will instead return NULL and set error."
So spice_vmc_output_stream_write_finish called g_task_propagate_pointer
and passed it as "result" to spice_vmc_write_finish which trigger
the "assertion 'result != NULL'" error. When spice_vmc_write_finish
returned a g_object_unref is called on the NULL object causing
the "assertion 'G_IS_OBJECT (object)' failed".
> I don't see nothing wrong with your proposal, actually thinks it
> is better to do the write on write_cb() and let the _finish()
> just provide the overall feedback of the _async() call.
>
> > To fix this, call spice_vmc_write_finish() immediately in the
> > corresponding write_cb().
> >
> > Signed-off-by: Jakub Janků <jjanku@xxxxxxxxxx>
>
> Acked-by: Victor Toso <victortoso@xxxxxxxxxx>
>
> > ---
> > src/vmcstream.c | 23 ++++++++++++-----------
> > 1 file changed, 12 insertions(+), 11 deletions(-)
> >
> > diff --git a/src/vmcstream.c b/src/vmcstream.c
> > index b6f6d1a..b7da103 100644
> > --- a/src/vmcstream.c
> > +++ b/src/vmcstream.c
> > @@ -397,18 +397,11 @@ spice_vmc_output_stream_write_fn(GOutputStream
> > *stream,
> >
> > static gssize
> > spice_vmc_output_stream_write_finish(GOutputStream *stream,
> > - GAsyncResult *simple,
> > + GAsyncResult *result,
> > GError **error)
> > {
> > - SpiceVmcOutputStream *self = SPICE_VMC_OUTPUT_STREAM(stream);
> > - GAsyncResult *res = g_task_propagate_pointer(G_TASK(simple), error);
> > - gssize bytes_written;
> > -
> > - SPICE_DEBUG("spicevmc write finish");
> > - bytes_written = spice_vmc_write_finish(self->channel, res, error);
> > - g_object_unref(res);
> > -
> > - return bytes_written;
> > + g_return_val_if_fail(g_task_is_valid(result, stream), -1);
> > + return g_task_propagate_int(G_TASK(result), error);
> > }
> >
> > static void
> > @@ -417,9 +410,17 @@ write_cb(GObject *source_object,
> > gpointer user_data)
> > {
> > GTask *task = user_data;
> > + GError *error = NULL;
> > + gssize bytes_written;
> >
> > - g_task_return_pointer(task, g_object_ref(res), g_object_unref);
> > + SPICE_DEBUG("spicevmc write finish");
> > + bytes_written = spice_vmc_write_finish(SPICE_CHANNEL(source_object),
> > res, &error);
> >
> > + if (error) {
> > + g_task_return_error(task, error);
> > + } else {
> > + g_task_return_int(task, bytes_written);
> > + }
> > g_object_unref(task);
> > }
> >
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