HDFS-9336. deleteSnapshot throws NPE when snapshotname is null. Contributed by Brahma Reddy Battula.

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -2415,6 +2415,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-9467. Fix data race accessing writeLockHeldTimeStamp in FSNamesystem.
     (Mingliang Liu via jing9)
 
+    HDFS-9336. deleteSnapshot throws NPE when snapshotname is null.
+    (Brahma Reddy Battula via aajisaka)
+
 Release 2.7.3 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java

@@ -1646,6 +1646,9 @@ class NameNodeRpcServer implements NamenodeProtocols {
   public void deleteSnapshot(String snapshotRoot, String snapshotName)
       throws IOException {
     checkNNStartup();
+    if (snapshotName == null || snapshotName.isEmpty()) {
+      throw new IOException("The snapshot name is null or empty.");
+    }
     namesystem.checkOperation(OperationCategory.WRITE);
     metrics.incrDeleteSnapshotOps();
     CacheEntry cacheEntry = RetryCache.waitForCompletion(retryCache);

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeRpcServerMethods.java

@@ -0,0 +1,84 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.hadoop.hdfs.server.namenode;
+
+import java.io.IOException;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.UnresolvedLinkException;
+import org.apache.hadoop.hdfs.HdfsConfiguration;
+import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocols;
+import org.apache.hadoop.security.AccessControlException;
+import org.apache.hadoop.test.GenericTestUtils;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+public class TestNameNodeRpcServerMethods {
+  private static NamenodeProtocols nnRpc;
+  private static Configuration conf;
+  private static MiniDFSCluster cluster;
+
+  /** Start a cluster */
+  @Before
+  public void setup() throws Exception {
+    conf = new HdfsConfiguration();
+    cluster = new MiniDFSCluster.Builder(conf).build();
+    cluster.waitActive();
+    nnRpc = cluster.getNameNode().getRpcServer();
+  }
+
+  /**
+   * Cleanup after the test
+   *
+   * @throws IOException
+   * @throws UnresolvedLinkException
+   * @throws SafeModeException
+   * @throws AccessControlException
+   */
+  @After
+  public void cleanup() throws IOException {
+    if (cluster != null)
+      cluster.shutdown();
+  }
+
+  @Test
+  public void testDeleteSnapshotWhenSnapshotNameIsEmpty() throws Exception {
+    String dir = "/testNamenodeRetryCache/testDelete";
+    try {
+      nnRpc.deleteSnapshot(dir, null);
+      Assert.fail("testdeleteSnapshot is not thrown expected exception ");
+    } catch (IOException e) {
+      // expected
+      GenericTestUtils.assertExceptionContains(
+          "The snapshot name is null or empty.", e);
+    }
+    try {
+      nnRpc.deleteSnapshot(dir, "");
+      Assert.fail("testdeleteSnapshot is not thrown expected exception");
+    } catch (IOException e) {
+      // expected
+      GenericTestUtils.assertExceptionContains(
+          "The snapshot name is null or empty.", e);
+    }
+
+  }
+
+}