wm: allow wm_find_by_client to be called with the root window

(cherry picked from commit b2bf3cc) Some window managers (e.g. qtile) may set _NET_ACTIVE_WINDOW to the root window, and in that case `update_ewmh_active_win` will call `wm_find_by_client` with the root, which crashes. Fixes #1384 Signed-off-by: Yuxuan Shui <[email protected]>
yshui · Nov 12, 2024 · 2fdeac0 · 2fdeac0
1 parent ab6ca6c
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,3 +1,9 @@
+# 12.x (unreleased)
+
+## Bug fixes
+
+* Fix assertion failure when running with some window managers (e.g. qtile) and no window is focused (#1384)
+
 # 12.4 (2024-Nov-09)
 
 ## Improvements

diff --git a/src/wm/wm.c b/src/wm/wm.c
@@ -187,7 +187,9 @@ struct wm_ref *wm_find(const struct wm *wm, xcb_window_t id) {
 
 struct wm_ref *wm_find_by_client(const struct wm *wm, xcb_window_t client) {
 	auto node = wm_tree_find(&wm->tree, client);
-	if (node == NULL) {
+	if (node == NULL || node->parent == NULL) {
+		// If `client` is the root window, we return NULL too, technically
+		// the root window doesn't have a client window.
 		return NULL;
 	}
 	auto toplevel = wm_tree_find_toplevel_for(&wm->tree, node);