ui: add a D-Bus display backend

The "dbus" display backend exports the QEMU consoles and other
UI-related interfaces over D-Bus.

By default, the connection is established on the session bus, but you
can specify a different bus with the "addr" option.

The backend takes the "org.qemu" service name, while still allowing
further instances to queue on the same name (so you can lookup all the
available instances too). It accepts any number of clients at this
point, although this is expected to evolve with options to restrict
clients, or only accept p2p via fd passing.

The interface is intentionally very close to the internal QEMU API,
and can be introspected or interacted with busctl/dfeet etc:

$ ./qemu-system-x86_64 -name MyVM -display dbus
$ busctl --user introspect org.qemu /org/qemu/Display1/Console_0

org.qemu.Display1.Console           interface -         -               -
.RegisterListener                   method    h         -               -
.SetUIInfo                          method    qqiiuu    -               -
.DeviceAddress                      property  s         "pci/0000/01.0" emits-change
.Head                               property  u         0               emits-change
.Height                             property  u         480             emits-change
.Label                              property  s         "VGA"           emits-change
.Type                               property  s         "Graphic"       emits-change
.Width                              property  u         640             emits-change
[...]

See the interfaces XML source file and Sphinx docs for the generated API
documentations.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 378 insertions, 0 deletions

diff --git a/ui/dbus-display1.xml b/ui/dbus-display1.xml
index e69de29bb2..0f0ae92e4d 100644
--- a/ui/dbus-display1.xml
+++ b/ui/dbus-display1.xml
@@ -0,0 +1,378 @@
+<?xml version="1.0" encoding="utf-8"?>
+<node>
+  <!--
+      org.qemu.Display1.VM:
+
+      This interface is implemented on ``/org/qemu/Display1/VM``.
+  -->
+  <interface name="org.qemu.Display1.VM">
+    <!--
+        Name:
+
+        The name of the VM.
+    -->
+    <property name="Name" type="s" access="read"/>
+
+    <!--
+        UUID:
+
+        The UUID of the VM.
+    -->
+    <property name="UUID" type="s" access="read"/>
+
+    <!--
+        ConsoleIDs:
+
+        The list of consoles available on ``/org/qemu/Display1/Console_$id``.
+    -->
+    <property name="ConsoleIDs" type="au" access="read"/>
+  </interface>
+
+  <!--
+      org.qemu.Display1.Console:
+
+      This interface is implemented on ``/org/qemu/Display1/Console_$id``. You
+      may discover available consoles through introspection or with the
+      :dbus:prop:`org.qemu.Display1.VM.ConsoleIDs` property.
+
+      A console is attached to a video device head. It may be "Graphic" or
+      "Text" (see :dbus:prop:`Type` and other properties).
+
+      Interactions with a console may be done with
+      :dbus:iface:`org.qemu.Display1.Keyboard` and
+      :dbus:iface:`org.qemu.Display1.Mouse` interfaces when available.
+  -->
+  <interface name="org.qemu.Display1.Console">
+    <!--
+        RegisterListener:
+        @listener: a Unix socket FD, for peer-to-peer D-Bus communication.
+
+        Register a console listener, which will receive display updates, until
+        it is disconnected.
+
+        Multiple listeners may be registered simultaneously.
+
+        The listener is expected to implement the
+        :dbus:iface:`org.qemu.Display1.Listener` interface.
+    -->
+    <method name="RegisterListener">
+      <arg type="h" name="listener" direction="in"/>
+    </method>
+
+    <!--
+        SetUIInfo:
+        @width_mm: the physical display width in millimeters.
+        @height_mm: the physical display height in millimeters.
+        @xoff: horizontal offset, in pixels.
+        @yoff: vertical offset, in pixels.
+        @width: console width, in pixels.
+        @height: console height, in pixels.
+
+        Modify the dimensions and display settings.
+    -->
+    <method name="SetUIInfo">
+      <arg name="width_mm" type="q" direction="in"/>
+      <arg name="height_mm" type="q" direction="in"/>
+      <arg name="xoff" type="i" direction="in"/>
+      <arg name="yoff" type="i" direction="in"/>
+      <arg name="width" type="u" direction="in"/>
+      <arg name="height" type="u" direction="in"/>
+    </method>
+
+    <!--
+        Label:
+
+        A user-friendly name for the console (for ex: "VGA").
+    -->
+    <property name="Label" type="s" access="read"/>
+
+    <!--
+        Head:
+
+        Graphical device head number.
+    -->
+    <property name="Head" type="u" access="read"/>
+
+    <!--
+        Type:
+
+        Console type ("Graphic" or "Text").
+    -->
+    <property name="Type" type="s" access="read"/>
+
+    <!--
+        Width:
+
+        Console width, in pixels.
+    -->
+    <property name="Width" type="u" access="read"/>
+
+    <!--
+        Height:
+
+        Console height, in pixels.
+    -->
+    <property name="Height" type="u" access="read"/>
+
+    <!--
+        DeviceAddress:
+
+        The device address (ex: "pci/0000/02.0").
+    -->
+    <property name="DeviceAddress" type="s" access="read"/>
+  </interface>
+
+  <!--
+      org.qemu.Display1.Keyboard:
+
+      This interface in implemented on ``/org/qemu/Display1/Console_$id`` (see
+      :dbus:iface:`~org.qemu.Display1.Console`).
+  -->
+  <interface name="org.qemu.Display1.Keyboard">
+    <!--
+        Press:
+        @keycode: QEMU key number (xtkbd + special re-encoding of high bit)
+
+        Send a key press event.
+    -->
+    <method name="Press">
+      <arg type="u" name="keycode" direction="in"/>
+    </method>
+
+    <!--
+        Release:
+        @keycode: QEMU key number (xtkbd + special re-encoding of high bit)
+
+        Send a key release event.
+    -->
+    <method name="Release">
+      <arg type="u" name="keycode" direction="in"/>
+    </method>
+
+    <!--
+        Modifiers:
+
+        The active keyboard modifiers::
+
+          Scroll = 1 << 0
+          Num    = 1 << 1
+          Caps   = 1 << 2
+    -->
+    <property name="Modifiers" type="u" access="read"/>
+  </interface>
+
+  <!--
+      org.qemu.Display1.Mouse:
+
+      This interface in implemented on ``/org/qemu/Display1/Console_$id`` (see
+      :dbus:iface:`~org.qemu.Display1.Console` documentation).
+
+      .. _dbus-button-values:
+
+      **Button values**::
+
+        Left       = 0
+        Middle     = 1
+        Right      = 2
+        Wheel-up   = 3
+        Wheel-down = 4
+        Side       = 5
+        Extra      = 6
+  -->
+  <interface name="org.qemu.Display1.Mouse">
+    <!--
+        Press:
+        @button: :ref:`button value<dbus-button-values>`.
+
+        Send a mouse button press event.
+    -->
+    <method name="Press">
+      <arg type="u" name="button" direction="in"/>
+    </method>
+
+    <!--
+        Release:
+        @button: :ref:`button value<dbus-button-values>`.
+
+        Send a mouse button release event.
+    -->
+    <method name="Release">
+      <arg type="u" name="button" direction="in"/>
+    </method>
+
+    <!--
+        SetAbsPosition:
+        @x: X position, in pixels.
+        @y: Y position, in pixels.
+
+        Set the mouse pointer position.
+
+        Returns an error if not :dbus:prop:`IsAbsolute`.
+    -->
+    <method name="SetAbsPosition">
+      <arg type="u" name="x" direction="in"/>
+      <arg type="u" name="y" direction="in"/>
+    </method>
+
+    <!--
+        RelMotion:
+        @dx: X-delta, in pixels.
+        @dy: Y-delta, in pixels.
+
+        Move the mouse pointer position, relative to the current position.
+
+        Returns an error if :dbus:prop:`IsAbsolute`.
+    -->
+    <method name="RelMotion">
+      <arg type="i" name="dx" direction="in"/>
+      <arg type="i" name="dy" direction="in"/>
+    </method>
+
+    <!--
+        IsAbsolute:
+
+        Whether the mouse is using absolute movements.
+    -->
+    <property name="IsAbsolute" type="b" access="read"/>
+  </interface>
+
+  <!--
+      org.qemu.Display1.Listener:
+
+      This client-side interface must be available on
+      ``/org/qemu/Display1/Listener`` when registering the peer-to-peer
+      connection with :dbus:meth:`~org.qemu.Display1.Console.Register`.
+  -->
+  <interface name="org.qemu.Display1.Listener">
+    <!--
+        Scanout:
+        @width: display width, in pixels.
+        @height: display height, in pixels.
+        @stride: data stride, in bytes.
+        @pixman_format: image format (ex: ``PIXMAN_X8R8G8B8``).
+        @data: image data.
+
+        Resize and update the display content.
+
+        The data to transfer for the display update may be large. The preferred
+        scanout method is :dbus:meth:`ScanoutDMABUF`, used whenever possible.
+    -->
+    <method name="Scanout">
+      <arg type="u" name="width" direction="in"/>
+      <arg type="u" name="height" direction="in"/>
+      <arg type="u" name="stride" direction="in"/>
+      <arg type="u" name="pixman_format" direction="in"/>
+      <arg type="ay" name="data" direction="in">
+        <annotation name="org.gtk.GDBus.C.ForceGVariant" value="true"/>
+      </arg>
+    </method>
+
+    <!--
+        Update:
+        @x: X update position, in pixels.
+        @y: Y update position, in pixels.
+        @width: update width, in pixels.
+        @height: update height, in pixels.
+        @stride: data stride, in bytes.
+        @pixman_format: image format (ex: ``PIXMAN_X8R8G8B8``).
+        @data: display image data.
+
+        Update the display content.
+
+        This method is only called after a :dbus:meth:`Scanout` call.
+    -->
+    <method name="Update">
+      <arg type="i" name="x" direction="in"/>
+      <arg type="i" name="y" direction="in"/>
+      <arg type="i" name="width" direction="in"/>
+      <arg type="i" name="height" direction="in"/>
+      <arg type="u" name="stride" direction="in"/>
+      <arg type="u" name="pixman_format" direction="in"/>
+      <arg type="ay" name="data" direction="in">
+        <annotation name="org.gtk.GDBus.C.ForceGVariant" value="true"/>
+      </arg>
+    </method>
+
+    <!--
+        ScanoutDMABUF:
+        @dmabuf: the DMABUF file descriptor.
+        @width: display width, in pixels.
+        @height: display height, in pixels.
+        @stride: stride, in bytes.
+        @fourcc: DMABUF fourcc.
+        @modifier: DMABUF modifier.
+        @y0_top: whether Y position 0 is the top or not.
+
+        Resize and update the display content with a DMABUF.
+    -->
+    <method name="ScanoutDMABUF">
+      <arg type="h" name="dmabuf" direction="in"/>
+      <arg type="u" name="width" direction="in"/>
+      <arg type="u" name="height" direction="in"/>
+      <arg type="u" name="stride" direction="in"/>
+      <arg type="u" name="fourcc" direction="in"/>
+      <!-- xywh? -->
+      <arg type="t" name="modifier" direction="in"/>
+      <arg type="b" name="y0_top" direction="in"/>
+    </method>
+
+    <!--
+        UpdateDMABUF:
+        @x: the X update position, in pixels.
+        @y: the Y update position, in pixels.
+        @width: the update width, in pixels.
+        @height: the update height, in pixels.
+
+        Update the display content with the current DMABUF and the given region.
+    -->
+    <method name="UpdateDMABUF">
+      <arg type="i" name="x" direction="in"/>
+      <arg type="i" name="y" direction="in"/>
+      <arg type="i" name="width" direction="in"/>
+      <arg type="i" name="height" direction="in"/>
+    </method>
+
+    <!--
+        Disable:
+
+        Disable the display (turn it off).
+    -->
+    <method name="Disable">
+    </method>
+
+    <!--
+        MouseSet:
+        @x: X mouse position, in pixels.
+        @y: Y mouse position, in pixels.
+        @on: whether the mouse is visible or not.
+
+        Set the mouse position and visibility.
+    -->
+    <method name="MouseSet">
+      <arg type="i" name="x" direction="in"/>
+      <arg type="i" name="y" direction="in"/>
+      <arg type="i" name="on" direction="in"/>
+    </method>
+
+    <!--
+        CursorDefine:
+        @width: cursor width, in pixels.
+        @height: cursor height, in pixels.
+        @hot_x: hot-spot X position, in pixels.
+        @hot_y: hot-spot Y position, in pixels.
+        @data: the cursor data.
+
+        Set the mouse cursor shape and hot-spot. The "data" must be ARGB, 32-bit
+        per pixel.
+    -->
+    <method name="CursorDefine">
+      <arg type="i" name="width" direction="in"/>
+      <arg type="i" name="height" direction="in"/>
+      <arg type="i" name="hot_x" direction="in"/>
+      <arg type="i" name="hot_y" direction="in"/>
+      <arg type="ay" name="data" direction="in">
+        <annotation name="org.gtk.GDBus.C.ForceGVariant" value="true"/>
+      </arg>
+    </method>
+  </interface>
+</node>