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, 7 insertions, 0 deletions

diff --git a/client/windows/platform.cpp b/client/windows/platform.cpp
index 580a40ae..075d2690 100644
--- a/client/windows/platform.cpp
+++ b/client/windows/platform.cpp
@@ -859,6 +859,11 @@ void WinPlatform::exit_modal_loop()
 
 int Platform::_clipboard_owner = Platform::owner_none;
 
+void Platform::set_clipboard_owner_unlocked(int new_owner)
+{
+    set_clipboard_owner(new_owner);
+}
+
 void Platform::set_clipboard_owner(int new_owner)
 {
     if (new_owner == owner_none) {
@@ -885,6 +890,8 @@ bool Platform::on_clipboard_grab(uint32_t *types, uint32_t type_count)
     EmptyClipboard();
     SetClipboardData(format, NULL);
     CloseClipboard();
+
+    set_clipboard_owner(owner_guest);
     return true;
 }