Hi, On Wed, Jan 16, 2019 at 12:40:36PM +0400, Marc-André Lureau wrote: > Hi > > On Wed, Jan 16, 2019 at 11:44 AM Victor Toso <victort...@redhat.com> wrote: > > > > From: Victor Toso <m...@victortoso.com> > > > > Similar to 172c521271a3d - if we don't, the agent might be waiting for > > data till some timeout happens in the system, blocking copy-paste > > feature and possibly freezing applications. > > > > A way to reproduce is copy-paste big clipboard data between two spice > > clients. > > > > Also add some documentation to the checks, in order to quickly > > understand what they are about. > > > > Related: https://gitlab.freedesktop.org/spice/win32/vd_agent/issues/6 > > Related: https://gitlab.freedesktop.org/spice/linux/vd_agent/issues/9 > > Related: https://bugzilla.redhat.com/show_bug.cgi?id=1594876 > > > > Signed-off-by: Victor Toso <victort...@redhat.com> > > --- > > src/spice-gtk-session.c | 32 +++++++++++++++++++++++++++----- > > 1 file changed, 27 insertions(+), 5 deletions(-) > > > > diff --git a/src/spice-gtk-session.c b/src/spice-gtk-session.c > > index 1a19bca..aa812d1 100644 > > --- a/src/spice-gtk-session.c > > +++ b/src/spice-gtk-session.c > > @@ -1015,12 +1015,30 @@ static gboolean clipboard_request(SpiceMainChannel > > *main, guint selection, > > int m; > > > > cb = get_clipboard_from_selection(s, selection); > > - g_return_val_if_fail(cb != NULL, FALSE); > > - g_return_val_if_fail(s->clipboard_by_guest[selection] == FALSE, FALSE); > > - g_return_val_if_fail(s->clip_grabbed[selection], FALSE); > > + if (cb == NULL) { > > + goto notify_agent; > > + } > > > > - if (read_only(self)) > > - return FALSE; > > + /* As we are holding clipboard data sent by selection-grab from agent, > > the > > + * selection-request of clipboard data from client OS must fail. We > > either > > from client OS? Here it's a signal handler for guest selection-request.
Yes, comment is wrong, should be:
/* As we are holding clipboard data sent by selection-grab from guest, the
* selection-request of clipboard data from guest must fail. We either
* sent a bad selection-grab to the guest or the agent is buggy. */
> This would clearly be a guest-side bug if we reach that
> condition (events are processed in order, and
> clipboard_by_guest is set synchronously).
Not true. Possible client-side bug, reproducible on X11, as I
discussed before. As mentioned in the comment, we are sending
wrong selection-grab to the guest.
> Not sure sending a reply is going to help much in that case...
It helps. Instead of blocking the application, it fails to paste
the clipboard and all is good.
> > + * sent a bad selection-grab to the agent or the agent is buggy. */
> > + if (s->clipboard_by_guest[selection]) {
> > + SPICE_DEBUG("clipboard: agent request: grab on hold by agent,
> > possible race");
> > + goto notify_agent;
> > + }
> > +
> > + /* The selection-request by agent should happen only if the clipboard
> > data is set
> > + * by client */
> > + if (!s->clip_grabbed[selection]) {
> > + SPICE_DEBUG("clipboard: agent request: data set by agent, possible
> > race");
> > + goto notify_agent;
> > + }
>
> This could be adding more race conditions. clip_grabbed is set
> asynchronously after owner changed, and indicate if the grab
> message was sent to the agent,
We send a selection-release on owner-change. If we receive a
selection-request before agent receives the selection-release,
this is expected but we should notify the guest, afaics.
> as you correctly say. It doesn't mean you can't request client
> clipboard content.
> I understand the racy case, but the condition seems wrong, it
> should attempt to request current client clipboard content, and
> fail/succeed after.
No. It should request the content from the grab that was sent. If
clipboard changed, previous grab gets invalidated and a
selection-release is sent and another selection-grab is sent with
the metadata of the new grab.
Proving recent data from old grab seems wrong.
>
> > + /* Ready only, still should reply to agent to avoid it waiting for
> > data */
>
> No, read-only shouldn't reply. We are lacking a way to tell the guest
> that the client is read-only though. So this may be acceptable for
> now, but we should have a TODO/FIXME..
Well, it should not happen anyway as on read-only we should not
send selection-grab. I'll fix and resend.
Thanks for the quick review.
> > + if (read_only(self)) {
> > + g_warning("clipboard: agent request: read only, deny request");
> > + goto notify_agent;
> > + }
> >
> > if (type == VD_AGENT_CLIPBOARD_UTF8_TEXT) {
> > gtk_clipboard_request_text(cb, clipboard_received_text_cb,
> > @@ -1039,6 +1057,10 @@ static gboolean clipboard_request(SpiceMainChannel
> > *main, guint selection,
> > }
> >
> > return TRUE;
> > +
> > +notify_agent:
> > + spice_main_channel_clipboard_selection_notify(s->main, selection,
> > type, NULL, 0);
> > + return FALSE;
> > }
> >
> > static void clipboard_release(SpiceMainChannel *main, guint selection,
> > --
> > 2.20.1
> >
> > _______________________________________________
> > Spice-devel mailing list
> > Spice-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/spice-devel
>
>
>
> --
> Marc-André Lureau
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