1 files changed, 12 insertions, 7 deletions
diff --git a/java/core/src/main/java/com/google/protobuf/UnsafeUtil.java b/java/core/src/main/java/com/google/protobuf/UnsafeUtil.java
index b09ff673..c9e2904b 100644
--- a/java/core/src/main/java/com/google/protobuf/UnsafeUtil.java
+++ b/java/core/src/main/java/com/google/protobuf/UnsafeUtil.java
@@ -33,6 +33,7 @@ package com.google.protobuf;
 import java.lang.reflect.Field;
 import java.nio.Buffer;
 import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
 import java.security.AccessController;
 import java.security.PrivilegedExceptionAction;
 import java.util.logging.Level;
@@ -83,6 +84,7 @@ final class UnsafeUtil {
     return HAS_UNSAFE_BYTEBUFFER_OPERATIONS;
   }
 
+
   static long objectFieldOffset(Field field) {
     return MEMORY_ACCESSOR.objectFieldOffset(field);
   }
@@ -287,7 +289,7 @@ final class UnsafeUtil {
   /**
    * Gets the {@code sun.misc.Unsafe} instance, or {@code null} if not available on this platform.
    */
-  private static sun.misc.Unsafe getUnsafe() {
+  static sun.misc.Unsafe getUnsafe() {
     sun.misc.Unsafe unsafe = null;
     try {
       unsafe =
@@ -367,6 +369,10 @@ final class UnsafeUtil {
       clazz.getMethod("objectFieldOffset", Field.class);
       clazz.getMethod("getLong", Object.class, long.class);
 
+      if (bufferAddressField() == null) {
+        return false;
+      }
+
       clazz.getMethod("getByte", long.class);
       clazz.getMethod("putByte", long.class, byte.class);
       clazz.getMethod("getInt", long.class);
@@ -387,12 +393,14 @@ final class UnsafeUtil {
 
   /** Finds the address field within a direct {@link Buffer}. */
   private static Field bufferAddressField() {
-    return field(Buffer.class, "address", long.class);
+    Field field = field(Buffer.class, "address");
+    return field != null && field.getType() == long.class ? field : null;
   }
 
   /** Finds the value field within a {@link String}. */
   private static Field stringValueField() {
-    return field(String.class, "value", char[].class);
+    Field field = field(String.class, "value");
+    return field != null && field.getType() == char[].class ? field : null;
   }
 
   /**
@@ -407,14 +415,11 @@ final class UnsafeUtil {
    * Gets the field with the given name within the class, or {@code null} if not found. If found,
    * the field is made accessible.
    */
-  private static Field field(Class<?> clazz, String fieldName, Class<?> expectedType) {
+  private static Field field(Class<?> clazz, String fieldName) {
     Field field;
     try {
       field = clazz.getDeclaredField(fieldName);
       field.setAccessible(true);
-      if (!field.getType().equals(expectedType)) {
-        return null;
-      }
     } catch (Throwable t) {
       // Failed to access the fields.
       field = null;