8004240: Return value from getAdapterPrefence() can be modified

Reviewed-by: okutsu

src/share/classes/sun/util/locale/provider/LocaleProviderAdapter.java

@@ -33,6 +33,7 @@ import java.text.spi.DateFormatSymbolsProvider;
 import java.text.spi.DecimalFormatSymbolsProvider;
 import java.text.spi.NumberFormatProvider;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 import java.util.ResourceBundle;
@@ -89,10 +90,7 @@ public abstract class LocaleProviderAdapter {
      * LocaleProviderAdapter preference list. The default list is intended
      * to behave the same manner in JDK7.
      */
-    private static Type[] adapterPreference = {
-        Type.JRE,
-        Type.SPI,
-    };
+    private static final List<Type> adapterPreference;
 
     /**
      * JRE Locale Data Adapter instance
@@ -129,10 +127,11 @@ public abstract class LocaleProviderAdapter {
     static {
         String order = AccessController.doPrivileged(
                            new sun.security.action.GetPropertyAction("java.locale.providers"));
-        // Override adapterPreference with the properties one
+        List<Type> typeList = new ArrayList<>();
+
+        // Check user specified adapter preference
         if (order != null && order.length() != 0) {
             String[] types = order.split(",");
-            List<Type> typeList = new ArrayList<>();
             for (String type : types) {
                 try {
                     Type aType = Type.valueOf(type.trim().toUpperCase(Locale.ROOT));
@@ -153,18 +152,22 @@ public abstract class LocaleProviderAdapter {
                     LocaleServiceProviderPool.config(LocaleProviderAdapter.class, e.toString());
                 }
             }
+        }
 
-            if (!typeList.isEmpty()) {
-                if (!typeList.contains(Type.JRE)) {
-                    // Append FALLBACK as the last resort.
-                    fallbackLocaleProviderAdapter = new FallbackLocaleProviderAdapter();
-                    typeList.add(Type.FALLBACK);
-                }
-                adapterPreference = typeList.toArray(new Type[0]);
+        if (!typeList.isEmpty()) {
+            if (!typeList.contains(Type.JRE)) {
+                // Append FALLBACK as the last resort.
+                fallbackLocaleProviderAdapter = new FallbackLocaleProviderAdapter();
+                typeList.add(Type.FALLBACK);
             }
+        } else {
+            // Default preference list
+            typeList.add(Type.JRE);
+            typeList.add(Type.SPI);
         }
-    }
 
+        adapterPreference = Collections.unmodifiableList(typeList);
+    }
 
     /**
      * Returns the singleton instance for each adapter type
@@ -202,7 +205,7 @@ public abstract class LocaleProviderAdapter {
     /**
      * Returns the preference order of LocaleProviderAdapter.Type
      */
-    public static Type[] getAdapterPreference() {
+    public static List<Type> getAdapterPreference() {
         return adapterPreference;
     }
 

test/java/util/Locale/Bug8004240.java

+/*
+ * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8004240
+ * @summary Verify that getAdapterPreference returns an unmodifiable list.
+ * @compile -XDignore.symbol.file Bug8004240.java
+ * @run main Bug8004240
+ */
+
+import java.util.List;
+import sun.util.locale.provider.LocaleProviderAdapter;
+
+public class Bug8004240 {
+
+    public static void main(String[] args) {
+        List<LocaleProviderAdapter.Type> types = LocaleProviderAdapter.getAdapterPreference();
+
+        try {
+            types.set(0, null);
+        } catch (UnsupportedOperationException e) {
+            // success
+            return;
+        }
+
+        throw new RuntimeException("LocaleProviderAdapter.getAdapterPrefence() returned a modifiable list.");
+    }
+}