From 9a6ef1e94c2c7cd937a6af668b33988057042520 Mon Sep 17 00:00:00 2001
From: Wale Ogunwale <ogunwale@google.com>
Date: Tue, 2 Jun 2015 13:41:00 -0700
Subject: [PATCH] Always have a handler for PendingIntents sent in the system
 process

It is possible for deadlocks to occur when sending/processing
PendingIntents due to components like AMS holding global service
locks when dispatching the broadcast without specifying an
handler and the receiver calling back into AMS.

We now set a default handler to process the broadcast on if we
are in the system process and a handler wasn't specified.

Bug: 19502993
Change-Id: Iccde32c6c1df997784155bc41ef39e52ee0f7243
---
 core/java/android/app/ActivityThread.java |  4 ++++
 core/java/android/app/PendingIntent.java  | 14 +++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/core/java/android/app/ActivityThread.java b/core/java/android/app/ActivityThread.java
index 2a98b6c74585d..83cec455918e8 100644
--- a/core/java/android/app/ActivityThread.java
+++ b/core/java/android/app/ActivityThread.java
@@ -1638,6 +1638,10 @@ public final class ActivityThread {
         return sCurrentActivityThread;
     }
 
+    public static boolean isSystem() {
+        return (sCurrentActivityThread != null) ? sCurrentActivityThread.mSystemThread : false;
+    }
+
     public static String currentOpPackageName() {
         ActivityThread am = currentActivityThread();
         return (am != null && am.getApplication() != null)
diff --git a/core/java/android/app/PendingIntent.java b/core/java/android/app/PendingIntent.java
index 2cfc1fa48f674..031854a6a69aa 100644
--- a/core/java/android/app/PendingIntent.java
+++ b/core/java/android/app/PendingIntent.java
@@ -25,11 +25,13 @@ import android.content.IIntentReceiver;
 import android.content.IIntentSender;
 import android.content.IntentSender;
 import android.os.Bundle;
+import android.os.Looper;
 import android.os.RemoteException;
 import android.os.Handler;
 import android.os.IBinder;
 import android.os.Parcel;
 import android.os.Parcelable;
+import android.os.Process;
 import android.os.UserHandle;
 import android.util.AndroidException;
 
@@ -206,10 +208,20 @@ public final class PendingIntent implements Parcelable {
         private int mResultCode;
         private String mResultData;
         private Bundle mResultExtras;
+        private static Handler sDefaultSystemHandler;
         FinishedDispatcher(PendingIntent pi, OnFinished who, Handler handler) {
             mPendingIntent = pi;
             mWho = who;
-            mHandler = handler;
+            if (handler == null && ActivityThread.isSystem()) {
+                // We assign a default handler for the system process to avoid deadlocks when
+                // processing receivers in various components that hold global service locks.
+                if (sDefaultSystemHandler == null) {
+                    sDefaultSystemHandler = new Handler(Looper.getMainLooper());
+                }
+                mHandler = sDefaultSystemHandler;
+            } else {
+                mHandler = handler;
+            }
         }
         public void performReceive(Intent intent, int resultCode, String data,
                 Bundle extras, boolean serialized, boolean sticky, int sendingUser) {