Add the XWAYLAND extension

This extension exists to serve one purpose: reliably identifying
Xwayland. Previous attempts at doing so included querying root window
properties, output names or input device names. All these attempts are
somewhat unreliable. Instead, let's use an extension - where that
extension is present we have an Xwayland server.

Clients should never need to do anything but check whether the extension
exists through XQueryExtension/XListExtensions.

This extension provides a single QueryVersion request only, and
that is only to provide future compatibility if we ever need anything
other than "this extension exists" functionality.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Olivier Fourdan <ofourdan@redhat.com>

2 files changed, 64 insertions, 0 deletions

diff --git a/include/X11/extensions/meson.build b/include/X11/extensions/meson.build
index d1ac281..9c91f22 100644
--- a/include/X11/extensions/meson.build
+++ b/include/X11/extensions/meson.build
@@ -87,6 +87,7 @@ install_headers(
     'XvMC.h',
     'XvMCproto.h',
     'Xvproto.h',
+    'xwaylandproto.h',
     subdir : 'X11/extensions'
 )
 
diff --git a/include/X11/extensions/xwaylandproto.h b/include/X11/extensions/xwaylandproto.h
new file mode 100644
index 0000000..49f048d
--- /dev/null
+++ b/include/X11/extensions/xwaylandproto.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright © 2022 Red Hat, Inc.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#ifndef _XWAYLAND_PROTO_H_
+#define _XWAYLAND_PROTO_H_
+
+#include <X11/Xproto.h>
+
+#define XWAYLAND_EXTENSION_NAME		"XWAYLAND"
+#define XWAYLAND_EXTENSION_MAJOR	1
+#define XWAYLAND_EXTENSION_MINOR	0
+
+/* Request opcodes */
+#define X_XwlQueryVersion		0
+
+#define XwlNumberRequests		1
+#define XwlNumberErrors			0
+#define XwlNumberEvents			0
+
+typedef struct {
+    CARD8   reqType;
+    CARD8   xwlReqType;
+    CARD16  length;
+    CARD16  majorVersion;
+    CARD16  minorVersion;
+} xXwlQueryVersionReq;
+#define sz_xXwlQueryVersionReq		8
+
+typedef struct {
+    BYTE    type;   /* X_Reply */
+    BYTE    pad1;
+    CARD16  sequenceNumber;
+    CARD32  length;
+    CARD16  majorVersion;
+    CARD16  minorVersion;
+    CARD32  pad2;
+    CARD32  pad3;
+    CARD32  pad4;
+    CARD32  pad5;
+    CARD32  pad6;
+} xXwlQueryVersionReply;
+#define sz_xXwlQueryVersionReply	32
+
+#endif