From e73a3dec6079434de10b9a865d9dde73af24e19d Mon Sep 17 00:00:00 2001
From: Geoffrey McRae <geoff@hostfission.com>
Date: Tue, 28 Jul 2026 13:05:40 +1000
Subject: [PATCH] [client] spice: handle clipboard request failures

---
 client/displayservers/Wayland/clipboard.c |  3 ++-
 client/displayservers/X11/clipboard.c     |  5 ++--
 client/include/app.h                      |  2 +-
 client/src/app.c                          | 33 ++++++++++++++++++-----
 4 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/client/displayservers/Wayland/clipboard.c b/client/displayservers/Wayland/clipboard.c
index c33da445..4b1330f3 100644
--- a/client/displayservers/Wayland/clipboard.c
+++ b/client/displayservers/Wayland/clipboard.c
@@ -595,7 +595,8 @@ void waylandCBNotice(LG_ClipboardData type)
 {
   wlCb.haveRequest = true;
   wlCb.type        = type;
-  app_clipboardRequest(waylandCBReplyFn, NULL);
+  if (!app_clipboardRequest(waylandCBReplyFn, NULL))
+    DEBUG_ERROR("Failed to request SPICE clipboard data");
 }
 
 void waylandCBRelease(void)
diff --git a/client/displayservers/X11/clipboard.c b/client/displayservers/X11/clipboard.c
index 2932a75a..068b830d 100644
--- a/client/displayservers/X11/clipboard.c
+++ b/client/displayservers/X11/clipboard.c
@@ -195,8 +195,9 @@ static void x11CBSelectionRequest(const XSelectionRequestEvent e)
     if (x11cb.aTypes[i] == e.target && x11cb.type == i)
     {
       // request the data
-      app_clipboardRequest(x11CBReplyFn, s);
-      return;
+      if (app_clipboardRequest(x11CBReplyFn, s))
+        return;
+      goto nodata;
     }
 
 nodata:
diff --git a/client/include/app.h b/client/include/app.h
index 8dabf784..6f663ce0 100644
--- a/client/include/app.h
+++ b/client/include/app.h
@@ -151,7 +151,7 @@ void app_clipboardRelease(void);
 void app_clipboardNotifyTypes(const LG_ClipboardData types[], int count);
 void app_clipboardNotifySize(const LG_ClipboardData type, size_t size);
 void app_clipboardData(const LG_ClipboardData type, uint8_t * data, size_t size);
-void app_clipboardRequest(const LG_ClipboardReplyFn replyFn, void * opaque);
+bool app_clipboardRequest(const LG_ClipboardReplyFn replyFn, void * opaque);
 
 /**
  * Show an alert on screen
diff --git a/client/src/app.c b/client/src/app.c
index b4d7a7f4..adae5bab 100644
--- a/client/src/app.c
+++ b/client/src/app.c
@@ -348,24 +348,43 @@ void app_clipboardData(const LG_ClipboardData type, uint8_t * data, size_t size)
     DEBUG_ERROR("Failed to send SPICE clipboard data");
 }
 
-void app_clipboardRequest(const LG_ClipboardReplyFn replyFn, void * opaque)
+bool app_clipboardRequest(const LG_ClipboardReplyFn replyFn, void * opaque)
 {
-  if (!g_params.clipboardToLocal)
-    return;
+  if (!g_params.clipboardToLocal || !replyFn || !g_state.cbRequestList)
+    return false;
 
+  const PSDataType type = g_state.cbType;
   struct CBRequest * cbr = malloc(sizeof(*cbr));
   if (!cbr)
   {
     DEBUG_ERROR("out of memory");
-    return;
+    return false;
   }
 
-  cbr->type    = g_state.cbType;
+  cbr->type    = type;
   cbr->replyFn = replyFn;
   cbr->opaque  = opaque;
-  ll_push(g_state.cbRequestList, cbr);
 
-  purespice_clipboardRequest(g_state.cbType);
+  if (!ll_push(g_state.cbRequestList, cbr))
+  {
+    free(cbr);
+    return false;
+  }
+
+  if (purespice_clipboardRequest(type))
+    return true;
+
+  /*
+   * Queue the callback before sending so a fast response cannot arrive before
+   * its request is visible. If another thread has already consumed it, the
+   * callback owns both cbr and opaque and the request completed successfully
+   * from the caller's perspective.
+   */
+  if (!ll_removeData(g_state.cbRequestList, cbr))
+    return true;
+
+  free(cbr);
+  return false;
 }
 
 static int mapSpiceToImGuiButton(uint32_t button)