Allow for the possibility of null ActivityContainer

When BinderProxy is passed in as the IBinder for
getEnclosingActivityContainer the activity manager cannot turn it into
an ActivityRecord. This causes NPE in ActivityThread which is Not Good
(tm).

Allowing null to be returned when requesting an ActivityContainer and
handling it appropriately fixes this bug.

Fixes bug 12473669.

Change-Id: I6937636042f8853b3ddc2df40be010e7391e41a5

2 files changed, 28 insertions, 7 deletions

diff --git a/core/java/android/app/ActivityManagerNative.java b/core/java/android/app/ActivityManagerNative.java
index 3bc2ee6..7b81713 100644
--- a/core/java/android/app/ActivityManagerNative.java
+++ b/core/java/android/app/ActivityManagerNative.java
@@ -2027,7 +2027,12 @@ public abstract class ActivityManagerNative extends Binder implements IActivityM
             IActivityContainer activityContainer =
                     createActivityContainer(parentActivityToken, callback);
             reply.writeNoException();
-            reply.writeStrongBinder(activityContainer.asBinder());
+            if (activityContainer != null) {
+                reply.writeInt(1);
+                reply.writeStrongBinder(activityContainer.asBinder());
+            } else {
+                reply.writeInt(0);
+            }
             return true;
         }
 
@@ -2036,7 +2041,12 @@ public abstract class ActivityManagerNative extends Binder implements IActivityM
             IBinder activityToken = data.readStrongBinder();
             IActivityContainer activityContainer = getEnclosingActivityContainer(activityToken);
             reply.writeNoException();
-            reply.writeStrongBinder(activityContainer.asBinder());
+            if (activityContainer != null) {
+                reply.writeInt(1);
+                reply.writeStrongBinder(activityContainer.asBinder());
+            } else {
+                reply.writeInt(0);
+            }
             return true;
         }
 
@@ -4670,8 +4680,13 @@ class ActivityManagerProxy implements IActivityManager
         data.writeStrongBinder((IBinder)callback);
         mRemote.transact(CREATE_ACTIVITY_CONTAINER_TRANSACTION, data, reply, 0);
         reply.readException();
-        IActivityContainer res =
-                IActivityContainer.Stub.asInterface(reply.readStrongBinder());
+        final int result = reply.readInt();
+        final IActivityContainer res;
+        if (result == 1) {
+            res = IActivityContainer.Stub.asInterface(reply.readStrongBinder());
+        } else {
+            res = null;
+        }
         data.recycle();
         reply.recycle();
         return res;
@@ -4685,8 +4700,13 @@ class ActivityManagerProxy implements IActivityManager
         data.writeStrongBinder(activityToken);
         mRemote.transact(GET_ACTIVITY_CONTAINER_TRANSACTION, data, reply, 0);
         reply.readException();
-        IActivityContainer res =
-                IActivityContainer.Stub.asInterface(reply.readStrongBinder());
+        final int result = reply.readInt();
+        final IActivityContainer res;
+        if (result == 1) {
+            res = IActivityContainer.Stub.asInterface(reply.readStrongBinder());
+        } else {
+            res = null;
+        }
         data.recycle();
         reply.recycle();
         return res;
diff --git a/core/java/android/app/ActivityThread.java b/core/java/android/app/ActivityThread.java
index 9ae2543..9f21a36 100644
--- a/core/java/android/app/ActivityThread.java
+++ b/core/java/android/app/ActivityThread.java
@@ -2225,7 +2225,8 @@ public final class ActivityThread {
         try {
             IActivityContainer container =
                     ActivityManagerNative.getDefault().getEnclosingActivityContainer(r.token);
-            final int displayId = container.getDisplayId();
+            final int displayId =
+                    container == null ? Display.DEFAULT_DISPLAY : container.getDisplayId();
             if (displayId > Display.DEFAULT_DISPLAY) {
                 Display display = dm.getRealDisplay(displayId, r.token);
                 baseContext = appContext.createDisplayContext(display);