From 660e7164c78358523abb46337f17881d299b59cb Mon Sep 17 00:00:00 2001
From: Jeremy Goldman <goldmanj@google.com>
Date: Mon, 19 Apr 2021 16:53:07 +0800
Subject: [PATCH] Check if the SubscriptionsChangeListener has been started
 before stop

calling mContext.unregisterReceiver on an unregistered broadcast
receiver will result in an exception. To make the
SubscriptionsChangeListener safe from this kind of error, add a check to
see whether start has been called before implementing stop's
functionality.

Bug: 184662284
Bug: 184521296
Test: atest -c SettingsUnitTests
Change-Id: Ic13911ee7573666f5d42ab4612c025968984ba47
---
 .../network/SubscriptionsChangeListener.java    | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/com/android/settings/network/SubscriptionsChangeListener.java b/src/com/android/settings/network/SubscriptionsChangeListener.java
index 192ee53fdb9..e13f85c5ab4 100644
--- a/src/com/android/settings/network/SubscriptionsChangeListener.java
+++ b/src/com/android/settings/network/SubscriptionsChangeListener.java
@@ -27,12 +27,15 @@ import android.os.Looper;
 import android.provider.Settings;
 import android.telephony.SubscriptionManager;
 import android.telephony.SubscriptionManager.OnSubscriptionsChangedListener;
+import android.util.Log;
 
 import com.android.internal.telephony.TelephonyIntents;
 
 /** Helper class for listening to changes in availability of telephony subscriptions */
 public class SubscriptionsChangeListener extends ContentObserver {
 
+    private static final String TAG = "SubscriptionsChangeListener";
+
     public interface SubscriptionsChangeListenerClient {
         void onAirplaneModeChanged(boolean airplaneModeEnabled);
         void onSubscriptionsChanged();
@@ -44,6 +47,7 @@ public class SubscriptionsChangeListener extends ContentObserver {
     private OnSubscriptionsChangedListener mSubscriptionsChangedListener;
     private Uri mAirplaneModeSettingUri;
     private BroadcastReceiver mBroadcastReceiver;
+    private boolean mRunning = false;
 
     public SubscriptionsChangeListener(Context context, SubscriptionsChangeListenerClient client) {
         super(new Handler(Looper.getMainLooper()));
@@ -75,12 +79,19 @@ public class SubscriptionsChangeListener extends ContentObserver {
         final IntentFilter radioTechnologyChangedFilter = new IntentFilter(
                 TelephonyIntents.ACTION_RADIO_TECHNOLOGY_CHANGED);
         mContext.registerReceiver(mBroadcastReceiver, radioTechnologyChangedFilter);
+        mRunning = true;
     }
 
     public void stop() {
-        mSubscriptionManager.removeOnSubscriptionsChangedListener(mSubscriptionsChangedListener);
-        mContext.getContentResolver().unregisterContentObserver(this);
-        mContext.unregisterReceiver(mBroadcastReceiver);
+        if (mRunning) {
+            mSubscriptionManager.removeOnSubscriptionsChangedListener(
+                    mSubscriptionsChangedListener);
+            mContext.getContentResolver().unregisterContentObserver(this);
+            mContext.unregisterReceiver(mBroadcastReceiver);
+            mRunning = false;
+        } else {
+            Log.d(TAG, "Stop has been called without associated Start.");
+        }
     }
 
     public boolean isAirplaneModeOn() {