From 83b2b0c68df66895658ef7d6d4629eaa95538d7c Mon Sep 17 00:00:00 2001
From: wilsonshih <wilsonshih@google.com>
Date: Fri, 25 Nov 2022 08:12:19 +0000
Subject: [PATCH] Don't prepare back animation from different user's
 task/activity.

Also fix a NPE crash for returnsToHomeRootTask.

Fixes: 260375814
Test: atest BackNavigationControllerTests
Change-Id: Ib84c035b1e6c32c8646d499910eac995a60e46e8
---
 .../server/wm/BackNavigationController.java       | 15 +++++++++++----
 .../server/wm/BackNavigationControllerTests.java  | 14 ++++++++++++++
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/services/core/java/com/android/server/wm/BackNavigationController.java b/services/core/java/com/android/server/wm/BackNavigationController.java
index 3bb02382b57c4..14d6d7bdfb7dd 100644
--- a/services/core/java/com/android/server/wm/BackNavigationController.java
+++ b/services/core/java/com/android/server/wm/BackNavigationController.java
@@ -16,6 +16,7 @@
 
 package com.android.server.wm;
 
+import static android.app.ActivityTaskManager.INVALID_TASK_ID;
 import static android.view.RemoteAnimationTarget.MODE_CLOSING;
 import static android.view.RemoteAnimationTarget.MODE_OPENING;
 import static android.view.WindowManager.LayoutParams.INVALID_WINDOW_TYPE;
@@ -226,9 +227,8 @@ class BackNavigationController {
 
             mBackAnimationInProgress = true;
             // We don't have an application callback, let's find the destination of the back gesture
-            Task finalTask = currentTask;
-            prevActivity = currentTask.getActivity(
-                    (r) -> !r.finishing && r.getTask() == finalTask && !r.isTopRunningActivity());
+            // The search logic should align with ActivityClientController#finishActivity
+            prevActivity = currentTask.topRunningActivity(currentActivity.token, INVALID_TASK_ID);
             // TODO Dialog window does not need to attach on activity, check
             // window.mAttrs.type != TYPE_BASE_APPLICATION
             if ((window.getParent().getChildCount() > 1
@@ -244,12 +244,14 @@ class BackNavigationController {
             } else if (currentTask.returnsToHomeRootTask()) {
                 // Our Task should bring back to home
                 removedWindowContainer = currentTask;
+                prevTask = currentTask.getDisplayArea().getRootHomeTask();
                 backType = BackNavigationInfo.TYPE_RETURN_TO_HOME;
                 mShowWallpaper = true;
             } else if (currentActivity.isRootOfTask()) {
                 // TODO(208789724): Create single source of truth for this, maybe in
                 //  RootWindowContainer
-                prevTask = currentTask.mRootWindowContainer.getTaskBelow(currentTask);
+                prevTask = currentTask.mRootWindowContainer.getTask(Task::showToCurrentUser,
+                        currentTask, false /*includeBoundary*/, true /*traverseTopToBottom*/);
                 removedWindowContainer = currentTask;
                 // If it reaches the top activity, we will check the below task from parent.
                 // If it's null or multi-window, fallback the type to TYPE_CALLBACK.
@@ -423,6 +425,11 @@ class BackNavigationController {
 
         void reset(@NonNull WindowContainer close, @NonNull WindowContainer open) {
             clearBackAnimateTarget(null);
+            if (close == null || open == null) {
+                Slog.e(TAG, "reset animation with null target close: "
+                        + close + " open: " + open);
+                return;
+            }
             if (close.asActivityRecord() != null && open.asActivityRecord() != null
                     && (close.asActivityRecord().getTask() == open.asActivityRecord().getTask())) {
                 mSwitchType = ACTIVITY_SWITCH;
diff --git a/services/tests/wmtests/src/com/android/server/wm/BackNavigationControllerTests.java b/services/tests/wmtests/src/com/android/server/wm/BackNavigationControllerTests.java
index f3f56e0709d8f..dc3515dec2f59 100644
--- a/services/tests/wmtests/src/com/android/server/wm/BackNavigationControllerTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/BackNavigationControllerTests.java
@@ -113,6 +113,20 @@ public class BackNavigationControllerTests extends WindowTestsBase {
                 any());
     }
 
+    @Test
+    public void backTypeBackToHomeDifferentUser() {
+        Task taskA = createTask(mDefaultDisplay);
+        ActivityRecord recordA = createActivityRecord(taskA);
+        Mockito.doNothing().when(recordA).reparentSurfaceControl(any(), any());
+        doReturn(false).when(taskA).showToCurrentUser();
+
+        withSystemCallback(createTopTaskWithActivity());
+        BackNavigationInfo backNavigationInfo = startBackNavigation();
+        assertWithMessage("BackNavigationInfo").that(backNavigationInfo).isNotNull();
+        assertThat(typeToString(backNavigationInfo.getType()))
+                .isEqualTo(typeToString(BackNavigationInfo.TYPE_RETURN_TO_HOME));
+    }
+
     @Test
     public void backTypeCrossActivityWhenBackToPreviousActivity() {
         CrossActivityTestCase testCase = createTopTaskWithTwoActivities();