Right now when kwin exits, the user is taken directly back to the login
screen. The login session exits, so all processes then are killed by the
session.
This patchset introduces a mechanism to safely restart kwin. The socket
(typically wayland-0) remains alive and persistent across restarts. This
means if any process reconnects through it's own mechanism or a crash
restart handler the socket appears to work, and blocks until the new
kwin restarts.
This makes it secure and race free.
If the screen was locked at the time kwin went down, this is also
secure. Kwin now checks the status from logind at the time of launch, so
will immediately restore a locked state before any other rendering.
Summary:
With the gneric X selections infrastructure and clipboard support the X
clipboard sync helper utility can be removed. Also rename its autotest as it
tests the inner workings of the new mechanism since this mechanism was
introduced.
Test Plan: Autotest still passes under new name.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: graesslin, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D15063
Summary:
The clipboard sync is done by a dedicated helper binary launched by
KWin. This helper binary is forced to xcb platform to piggy-back on
Qt's implementation of the X11 clipboard. In addition it implements
the Wayland clipboard - which is much simpler. Reading the Wayland
clipboard is based on the implementation in QtWayland.
KWin internally knows the DataDeviceInterface belonging to the helper
application. Whenever an xwayland client is focussed, this DataDevice
is allowed to set the selection and KWin manually updates the current
selection in the SeatInterface. By that the sync from X11 to Wayland
is implemented. When afterwards a Wayland client is selected, it's sent
the current selection which references the X clipboard and a data
transfer can be initiated in the normal Wayland way.
For the other direction KWin sends the current selection to the helper's
DataDevice whenever an xwayland window is focused. The helper application
reads the Wayland clipboard and sets it on the X11 clipboard. Thus the
Wayland clipboard is synced to X11.
The approach used here will also be useful for implementing a clipboard
manager (aka klipper).
Currently the implementation is not yet fully completed. We need to
make sure that the helper application gets restarted in case of a crash.
Test Plan: See added test case
Reviewers: #plasma_on_wayland, #kwin
Subscribers: plasma-devel, kwin
Tags: #plasma_on_wayland, #kwin
Differential Revision: https://phabricator.kde.org/D1973
