From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Valentin Iftime <valiiftime@google.com>
Date: Mon, 16 Oct 2023 09:29:17 +0200
Subject: [PATCH] Prioritize system toasts

 Insert toasts from system packages at the front of the queue
  to ensure that apps can't spam with toast to delay system toasts from showing.

Test: atest NotificationManagerServiceTest
Bug: 293301736
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:67721fcfb3198f220c90c976f870407a0bb8d6c6)
Merged-In: I13547f853476bc88d12026c545aba9f857ce8724
Change-Id: I13547f853476bc88d12026c545aba9f857ce8724
---
 .../NotificationManagerService.java           | 33 ++++++++-
 .../NotificationManagerServiceTest.java       | 68 +++++++++++++++++++
 2 files changed, 99 insertions(+), 2 deletions(-)

diff --git a/services/core/java/com/android/server/notification/NotificationManagerService.java b/services/core/java/com/android/server/notification/NotificationManagerService.java
index 11c89bbdf4d9..dfc9c135c7da 100755
--- a/services/core/java/com/android/server/notification/NotificationManagerService.java
+++ b/services/core/java/com/android/server/notification/NotificationManagerService.java
@@ -3042,8 +3042,19 @@ public class NotificationManagerService extends SystemService {
                         mWindowManagerInternal.addWindowToken(windowToken, TYPE_TOAST, displayId);
                         record = getToastRecord(callingUid, callingPid, pkg, token, text, callback,
                                 duration, windowToken, displayId, textCallback);
-                        mToastQueue.add(record);
-                        index = mToastQueue.size() - 1;
+
+                        // Insert system toasts at the front of the queue
+                        int systemToastInsertIdx = mToastQueue.size();
+                        if (isSystemToast) {
+                            systemToastInsertIdx = getInsertIndexForSystemToastLocked();
+                        }
+                        if (systemToastInsertIdx < mToastQueue.size()) {
+                            index = systemToastInsertIdx;
+                            mToastQueue.add(index, record);
+                        } else {
+                            mToastQueue.add(record);
+                            index = mToastQueue.size() - 1;
+                        }
                         keepProcessAliveForToastIfNeededLocked(callingPid);
                     }
                     // If it's at index 0, it's the current toast.  It doesn't matter if it's
@@ -3059,6 +3070,24 @@ public class NotificationManagerService extends SystemService {
             }
         }
 
+        @GuardedBy("mToastQueue")
+        private int getInsertIndexForSystemToastLocked() {
+            // If there are other system toasts: insert after the last one
+            int idx = 0;
+            for (ToastRecord r : mToastQueue) {
+                if (idx == 0 && mIsCurrentToastShown) {
+                    idx++;
+                    continue;
+                }
+                /* BACKPORT: In Android 11, Toastrecord does not have the attribute isSystemToast */
+                if (!isUidSystemOrPhone(r.uid) && !PackageManagerService.PLATFORM_PACKAGE_NAME.equals(r.pkg)) {
+                    return idx;
+                }
+                idx++;
+            }
+            return idx;
+        }
+
         /**
          * Implementation note: Our definition of foreground for toasts is an implementation matter
          * and should strike a balance between functionality and anti-abuse effectiveness. We
diff --git a/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java b/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java
index 3a108144ad66..011c408492fa 100755
--- a/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java
+++ b/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java
@@ -5510,6 +5510,74 @@ public class NotificationManagerServiceTest extends UiServiceTestCase {
         assertEquals(1, mService.mToastQueue.size());
     }
 
+    @Test
+    public void testPrioritizeSystemToasts() throws Exception {
+        // Insert non-system toasts
+        final String testPackage = "testPackageName";
+        assertEquals(0, mService.mToastQueue.size());
+        mService.isSystemUid = false;
+        mService.isSystemAppId = false;
+        setToastRateIsWithinQuota(true);
+        setIfPackageHasPermissionToAvoidToastRateLimiting(testPackage, false);
+
+        // package is not suspended
+        when(mPackageManager.isPackageSuspendedForUser(testPackage, UserHandle.getUserId(mUid)))
+                .thenReturn(false);
+
+        INotificationManager nmService = (INotificationManager) mService.mService;
+
+        // Enqueue maximum number of toasts for test package
+        for (int i = 0; i < NotificationManagerService.MAX_PACKAGE_TOASTS; i++) {
+            nmService.enqueueTextToast(testPackage, new Binder(), "Text", 2000, 0, null);
+        }
+
+        // Enqueue system toast
+        final String testPackageSystem = "testPackageNameSystem";
+        mService.isSystemUid = true;
+        setIfPackageHasPermissionToAvoidToastRateLimiting(testPackageSystem, false);
+        when(mPackageManager.isPackageSuspendedForUser(testPackageSystem, UserHandle.getUserId(mUid)))
+                .thenReturn(false);
+
+        nmService.enqueueToast(testPackageSystem, new Binder(), new TestableToastCallback(), 2000, 0);
+
+        // System toast is inserted at the front of the queue, behind current showing toast
+        assertEquals(testPackageSystem, mService.mToastQueue.get(1).pkg);
+    }
+
+    @Test
+    public void testPrioritizeSystemToasts_enqueueAfterExistingSystemToast() throws Exception {
+        // Insert system toasts
+        final String testPackageSystem1 = "testPackageNameSystem1";
+        assertEquals(0, mService.mToastQueue.size());
+        mService.isSystemUid = true;
+        setToastRateIsWithinQuota(true);
+        setIfPackageHasPermissionToAvoidToastRateLimiting(testPackageSystem1, false);
+
+        // package is not suspended
+        when(mPackageManager.isPackageSuspendedForUser(testPackageSystem1, UserHandle.getUserId(mUid)))
+                .thenReturn(false);
+
+        INotificationManager nmService = (INotificationManager) mService.mService;
+
+        // Enqueue maximum number of toasts for test package
+        for (int i = 0; i < NotificationManagerService.MAX_PACKAGE_TOASTS; i++) {
+            nmService.enqueueTextToast(testPackageSystem1, new Binder(), "Text", 2000, 0, null);
+        }
+
+        // Enqueue another system toast
+        final String testPackageSystem2 = "testPackageNameSystem2";
+        mService.isSystemUid = true;
+        setIfPackageHasPermissionToAvoidToastRateLimiting(testPackageSystem2, false);
+        when(mPackageManager.isPackageSuspendedForUser(testPackageSystem2, UserHandle.getUserId(mUid)))
+                .thenReturn(false);
+
+        nmService.enqueueToast(testPackageSystem2, new Binder(), new TestableToastCallback(), 2000, 0);
+
+        // System toast is inserted at the back of the queue, after the other system toasts
+        assertEquals(testPackageSystem2,
+                mService.mToastQueue.get(mService.mToastQueue.size() - 1).pkg);
+    }
+
     private void setAppInForegroundForToasts(int uid, boolean inForeground) {
         int importance = (inForeground) ? IMPORTANCE_FOREGROUND : IMPORTANCE_NONE;
         when(mActivityManager.getUidImportance(mUid)).thenReturn(importance);
