Hi, On Thu, Mar 14, 2019 at 6:18 PM Marc-André Lureau <marcandre.lureau@xxxxxxxxx> wrote: > > Hi > > On Thu, Feb 28, 2019 at 8:12 PM Jakub Janků <jjanku@xxxxxxxxxx> wrote: > > > > If two grab messages in opposite directions "meet" on their way > > to their destinations, we end up in a state when both spice-gtk > > and spice-vdagent think that the other component can provide > > clipboard data. As a consequence of this, neither of them can. > > > > This is a bug in the spice-protocol. To mitigate the issue, > > accept grab only from the side that currently has keyboard focus, > > this means: > > (1) spice-gtk has focus ==> > > * accept grabs from vdagent, > > * ignore grabs from other apps running in the host > > (2) spice-gtk doesn't have focus ==> > > * accept grabs from other apps running in the host > > * ignore grabs from vdagent > > > > The check in clipboard_owner_change() is X11-specific, > > because on Wayland, spice-gtk is first notified about the > > owner-change once it gains focus. > > > > The check in clipboard_grab() can be generic. > > Note that on Wayland, calling gtk_clipboard_set_with_owner() > > while not having focus doesn't have any effect anyway, > > only focused clients can set clipboard. > > > > With this patch, the race can still occur around the time > > when focus changes (rare, but possible), on X11 as well as Wayland. > > > > Related: https://gitlab.freedesktop.org/spice/spice-gtk/issues/82 > > Related: https://bugzilla.redhat.com/show_bug.cgi?id=1594876 > > > > Signed-off-by: Jakub Janků <jjanku@xxxxxxxxxx> > > --- > > > > Victor, half of this patch is basically yours, > > so feel free to add signed-off or something, > > in the case this gets upstream :) > > > > --- > > src/spice-gtk-session.c | 13 +++++++++++++ > > 1 file changed, 13 insertions(+) > > > > diff --git a/src/spice-gtk-session.c b/src/spice-gtk-session.c > > index b48f92a..7b7370c 100644 > > --- a/src/spice-gtk-session.c > > +++ b/src/spice-gtk-session.c > > @@ -680,6 +680,13 @@ static void clipboard_owner_change(GtkClipboard *clipboard, > > s->clip_hasdata[selection] = FALSE; > > return; > > } > > + > > + if (GDK_IS_X11_DISPLAY(gdk_display_get_default()) && > > + spice_gtk_session_get_keyboard_has_focus(self)) { > > + SPICE_DEBUG("%s: spice-gtk has keyboard focus, " > > + "ignoring grab from other app", __FUNCTION__); > > + return; > > + } > > #endif > > This will break clipboard managers interactions, which may take the > clipboard content, save it and/or modify it. Depends on the implementation of the given clipboard manager, I'd say. I tried the "clipboard indicator" you're using. Seems like no problem there :) > > > > > s->clip_hasdata[selection] = TRUE; > > @@ -823,6 +830,12 @@ static gboolean clipboard_grab(SpiceMainChannel *main, guint selection, > > cb = get_clipboard_from_selection(s, selection); > > g_return_val_if_fail(cb != NULL, FALSE); > > > > + if (!spice_gtk_session_get_keyboard_has_focus(self)) { > > + SPICE_DEBUG("%s: spice-gtk doesn't have keyboard focus, " > > + "ignoring grab from guest agent", __FUNCTION__); > > + return FALSE; > > + } > > > Beside automation, the cursor alone may easily create a new clipboard > content which won't be available to the client side (the auto-grab may > fail to follow cursor etc). > > It's a bit unclear why it's not X11 specific but for client side > change it is, this could deserve a code comment. Tried to describe that in the commit log. I could add a comment in the code as well. > > All in all, this feels weak and breaks some legitimate cases. > > I am not very strongly against this, as I understand it may help with > some races we discussed, Is this an ack or nack? Seems like we're just going round in circles now... > but it feels like the problem is elsewhere sorry, but that's very vague, I have no idea what you're referring to > and we need a better solution to prevent the race from happening. > > I haven't read the bug reports: this kind of workaround needs a > description of a broken use case (not a theoretical description of a > race that "never" happen in practice). I described a broken case in the previous email: KDE with klipper, "prevent empty clipboard" enabled + slow network Cheers, Jakub > > > > + > > for (n = 0; n < ntypes; ++n) { > > found = FALSE; > > for (m = 0; m < SPICE_N_ELEMENTS(atom2agent); m++) { > > -- > > 2.20.1 > > > > _______________________________________________ > > Spice-devel mailing list > > Spice-devel@xxxxxxxxxxxxxxxxxxxxx > > https://lists.freedesktop.org/mailman/listinfo/spice-devel > > > > -- > Marc-André Lureau _______________________________________________ Spice-devel mailing list Spice-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/spice-devel