Updating getInterfaces to return copy

To avoid situation where the contents of BinderInterfaceContainer are
modified while something is iterating over getInterfaces, the method is
updated to return a copy instead of an unmodifiable collection.

Bug: 171420304
Test: atest BinderInterfaceContainerTest
Change-Id: Ice21b279912c6597b3e13ae4b4c3e2dbab9b4d37
diff --git a/service/src/com/android/car/BinderInterfaceContainer.java b/service/src/com/android/car/BinderInterfaceContainer.java
index 32f7eb9..c159007 100644
--- a/service/src/com/android/car/BinderInterfaceContainer.java
+++ b/service/src/com/android/car/BinderInterfaceContainer.java
@@ -23,8 +23,8 @@
 
 import com.android.internal.annotations.GuardedBy;
 
+import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -148,12 +148,11 @@
     }
 
     /**
-     * Returns an unmodified collection containing all registered {@link BinderInterface} objects
-     * with this container.
+     * Returns a shallow copy of all registered {@link BinderInterface} objects in this container.
      */
     public Collection<BinderInterface<T>> getInterfaces() {
         synchronized (mLock) {
-            return Collections.unmodifiableCollection(mBinders.values());
+            return new ArrayList<>(mBinders.values());
         }
     }
 
diff --git a/tests/carservice_unit_test/src/android/car/BinderInterfaceContainerTest.java b/tests/carservice_unit_test/src/android/car/BinderInterfaceContainerTest.java
new file mode 100644
index 0000000..6c7aa99
--- /dev/null
+++ b/tests/carservice_unit_test/src/android/car/BinderInterfaceContainerTest.java
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.car;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.os.IBinder;
+import android.os.IInterface;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+
+import com.android.car.BinderInterfaceContainer;
+import com.android.car.BinderInterfaceContainer.BinderInterface;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+@RunWith(AndroidJUnit4.class)
+public final class BinderInterfaceContainerTest {
+    @Test
+    public void getInterfaces_returnsCopy() {
+        BinderInterfaceContainer<IInterface> container = new BinderInterfaceContainer<>();
+        TestBinderInterface interfaceOne = new TestBinderInterface();
+        container.addBinder(interfaceOne);
+
+        Collection<BinderInterface<IInterface>> interfaces = container.getInterfaces();
+
+        TestBinderInterface interfaceTwo = new TestBinderInterface();
+        container.addBinder(interfaceTwo);
+
+        assertThat(interfaces).hasSize(1);
+        List<BinderInterface<IInterface>> interfaceList = new ArrayList<>(interfaces);
+        assertThat(interfaceList.get(0).binderInterface).isEqualTo(interfaceOne);
+
+        assertThat(container.getInterfaces()).hasSize(2);
+    }
+
+    private final class TestBinderInterface extends android.os.Binder implements IInterface {
+        @Override
+        public IBinder asBinder() {
+            return this;
+        }
+    }
+}