From f6de3eca01e873a4216e172cacb6c7447bf9f020 Mon Sep 17 00:00:00 2001
From: Olivier Fourdan <ofourdan@redhat.com>
Date: Tue, 10 Mar 2026 13:42:18 +0100
Subject: [PATCH] dix: Add a selection bridge callback

This is intended to be used to implement selection bridges in mixed
windowing systems such as Xwayland.

This adds a new SelectionBridgeCallback along with a new
SelectionBridgeInfoRec to convey the information from a selection
request so that a DDX such as Xwayland can bridge that to some other
clipboard implementation from another windowing system directly from the
DDX.

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Assisted-by: Cursor AI
Assisted-by: Claude Code <noreply@anthropic.com>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2139>
---
 dix/selection.c     | 28 ++++++++++++++++++++++++++++
 include/selection.h | 17 +++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/dix/selection.c b/dix/selection.c
index df5269f52..622e0646a 100644
--- a/dix/selection.c
+++ b/dix/selection.c
@@ -66,6 +66,7 @@ SOFTWARE.
 
 Selection *CurrentSelections;
 CallbackListPtr SelectionCallback;
+CallbackListPtr SelectionBridgeCallback;
 
 int
 dixLookupSelection(Selection ** result, Atom selectionName,
@@ -247,6 +248,25 @@ ProcGetSelectionOwner(ClientPtr client)
     return Success;
 }
 
+static void
+CallSelectionBridgeCallback(ClientPtr pClient, Selection *pSel, xEvent *event)
+{
+    SelectionBridgeInfoRec info;
+
+    if (!pSel->pWin)
+        return;
+
+    info.screen = pSel->pWin->drawable.pScreen;
+    info.client = pClient;
+    info.requestor = event->u.selectionRequest.requestor;
+    info.selection = event->u.selectionRequest.selection;
+    info.target = event->u.selectionRequest.target;
+    info.property = event->u.selectionRequest.property;
+    info.time = ClientTimeToServerTime(event->u.selectionRequest.time);
+
+    CallCallbacks(&SelectionBridgeCallback, &info);
+}
+
 int
 ProcConvertSelection(ClientPtr client)
 {
@@ -291,6 +311,14 @@ ProcConvertSelection(ClientPtr client)
             WriteEventsToClient(pSel->client, 1, &event);
             return Success;
         }
+
+        /* If the selection is owned by the server client, and there are
+         * selection bridge callbacks registered, call them now.
+         */
+        if (pSel->client == serverClient && SelectionBridgeCallback != NULL) {
+            CallSelectionBridgeCallback(client, pSel, &event);
+            return Success;
+        }
     }
 
     event.u.u.type = SelectionNotify;
diff --git a/include/selection.h b/include/selection.h
index 7a516f14a..500439e37 100644
--- a/include/selection.h
+++ b/include/selection.h
@@ -49,6 +49,7 @@ SOFTWARE.
 
 #include "dixstruct.h"
 #include "privates.h"
+#include "screenint.h"
 
 /*
  *  Selection data structures
@@ -87,6 +88,22 @@ typedef struct {
     SelectionCallbackKind kind;
 } SelectionInfoRec;
 
+/*
+ * Selection bridge callback:
+ * can be used to bridge a selection request to the target clients.
+ */
+extern _X_EXPORT CallbackListPtr SelectionBridgeCallback;
+
+typedef struct {
+    ScreenPtr screen;
+    ClientPtr client;
+    Window requestor;
+    Atom selection;
+    Atom target;
+    Atom property;
+    TimeStamp time;
+} SelectionBridgeInfoRec;
+
 /*
  *  Selection server internals
  */