spicec: Move setting of clipboard_owner to guest to platform code

Atleast under x11 there is a race condition when setting the clipboard
owner to guest from the RedClient code rather then doing it in Platform.

After the XSetSelectionOwner() in Platform::on_clipboard_grab(), which runs
from the main message loop thread, the x11 event thread can receive a
SelectionRequest event from another x11 app, before the RedClient code
has set the clipboard owner, which will trigger the owner != guest
check in the SelectionRequest event handling code.

By moving the setting of the owner in to Platform::on_clipboard_grab() it
gets protected by the clipboard lock, which closes this tiny race.

1 files changed, 2 insertions, 0 deletions

diff --git a/client/platform.h b/client/platform.h
index af4a0f6c..a9a1715b 100644
--- a/client/platform.h
+++ b/client/platform.h
@@ -132,6 +132,8 @@ public:
     static int  get_clipboard_owner() { return _clipboard_owner; }
 
 private:
+    static void set_clipboard_owner_unlocked(int new_owner);
+
     static int _clipboard_owner;
 };