HADOOP-18471. Fixed ArrayIndexOutOfBoundsException in DefaultStringifier (#4957)

Contributed by FuzzingTeam

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/DefaultStringifier.java

@@ -158,6 +158,9 @@ public class DefaultStringifier<T> implements Stringifier<T> {
   public static <K> void storeArray(Configuration conf, K[] items,
       String keyName) throws IOException {
 
+    if (items.length == 0) {
+      throw new IndexOutOfBoundsException();
+    }
     DefaultStringifier<K> stringifier = new DefaultStringifier<K>(conf, 
         GenericsUtil.getClass(items[0]));
     try {

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/TestDefaultStringifier.java

@@ -26,6 +26,7 @@ import org.junit.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import static org.apache.hadoop.test.LambdaTestUtils.intercept;
 import static org.junit.Assert.assertEquals;
 
 public class TestDefaultStringifier {
@@ -98,7 +99,7 @@ public class TestDefaultStringifier {
   }
 
   @Test
-  public void testStoreLoadArray() throws IOException {
+  public void testStoreLoadArray() throws Exception {
     LOG.info("Testing DefaultStringifier#storeArray() and #loadArray()");
     conf.set("io.serializations", "org.apache.hadoop.io.serializer.JavaSerialization");
 
@@ -107,6 +108,8 @@ public class TestDefaultStringifier {
     Integer[] array = new Integer[] {1,2,3,4,5};
 
 
+    intercept(IndexOutOfBoundsException.class, () ->
+        DefaultStringifier.storeArray(conf, new Integer[] {}, keyName));
     DefaultStringifier.storeArray(conf, array, keyName);
 
     Integer[] claimedArray = DefaultStringifier.<Integer>loadArray(conf, keyName, Integer.class);