desktop-plasma: Add patch fixing infinite loop in plasmashell

This fix has also been sent upstream [1] but won't be available in a
release any time soon.

[1] https://invent.kde.org/plasma/plasma-desktop/-/merge_requests/2574

1 files changed, 70 insertions, 0 deletions

diff --git a/desktop-plasma/patches/kde-plasma/plasma-desktop/0001-activitymanager-Avoid-infinite-loop-in-ActivityList.patch b/desktop-plasma/patches/kde-plasma/plasma-desktop/0001-activitymanager-Avoid-infinite-loop-in-ActivityList.patch
new file mode 100644
index 0000000..977ce66
--- /dev/null
+++ b/desktop-plasma/patches/kde-plasma/plasma-desktop/0001-activitymanager-Avoid-infinite-loop-in-ActivityList.patch
@@ -0,0 +1,70 @@
+From 6ee8b63fa490477b03f4104ed91ab585c53d8001 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Wolfgang=20M=C3=BCller?= <wolf@oriole.systems>
+Date: Sat, 12 Oct 2024 14:39:03 +0200
+Subject: [PATCH] activitymanager: Avoid infinite loop in ActivityList
+
+When updating the selection in the activity manager we search through
+activities using using a do while loop. Each iteration of the loop
+increments or decrements selectedIndex depending on the search
+direction, wrapping around if needed. The loop stops only once we have
+found a visible item to select or if we have looped back to the item we
+started with. The latter is done by comparing selectedIndex with the
+index we started at, saved earlier in startingWithSelected.
+
+If the user triggers the activity manager and starts searching
+activities right away without first selecting one, startingWithSelected
+will remain at its initial value of -1. If there are no matches and the
+user then attempts to select the next or previous item, we will loop
+infinitely because there are no visible items and selectedIndex can
+never again equal -1. This infinite loop will hang the entirety of
+plasmashell.
+
+To fix this, keep track of how many items we have visited and forcibly
+break out of the loop if we have seen all activities (meaning that we
+have wrapped around). This does not rely on the value of either
+selectedIndex or startingWithSelected, meaning it also works if no
+activities are visible. We can also keep the old selection behaviour by
+setting selectedIndex to startingWithSelected right before we break.
+---
+ .../contents/activitymanager/ActivityList.qml      | 14 ++++++++++----
+ 1 file changed, 10 insertions(+), 4 deletions(-)
+
+diff --git a/desktoppackage/contents/activitymanager/ActivityList.qml b/desktoppackage/contents/activitymanager/ActivityList.qml
+index 4b3402736..7a5cd7bab 100644
+--- a/desktoppackage/contents/activitymanager/ActivityList.qml
++++ b/desktoppackage/contents/activitymanager/ActivityList.qml
+@@ -28,9 +28,11 @@ Flickable {
+     function _selectRelativeToCurrent(distance)
+     {
+         var startingWithSelected = selectedIndex;
++        var visited = 0;
+ 
+         do {
+             selectedIndex += distance;
++            visited++;
+ 
+             if (selectedIndex >= activitiesList.count) {
+                 selectedIndex = 0;
+@@ -40,11 +42,15 @@ Flickable {
+                 selectedIndex = activitiesList.count - 1;
+             }
+ 
+-            // Searching for the first item that is visible, or back to the one
+-            // that we started with
+-        } while (!activitiesList.itemAt(selectedIndex).visible
+-                        && startingWithSelected !== selectedIndex);
++            if (visited >= activitiesList.count) {
++                // we've visited all activities but could not find a visible
++                // one, so stop searching and select the one we started with
++                selectedIndex = startingWithSelected;
++                break;
++            }
+ 
++            // Searching for the first item that is visible
++        } while (!activitiesList.itemAt(selectedIndex).visible);
+         _updateSelectedItem();
+ 
+     }
+-- 
+2.47.0
+