HDFS-2956. calling fetchdt without a --renewer argument throws NPE (Contributed by Vinayakumar B)HDFS-2956. calling fetchdt without a --renewer argument throws NPE (Contributed by Vinayakumar B)

(cherry picked from commit b48908033fcac7a4bd4313c1fd1457999fba08e1)

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDelegationTokenFetcher.java

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

@@ -693,6 +693,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-8749. Fix findbugs warnings in BlockManager.java.
     (Brahma Reddy Battula via aajisaka)
 
+    HDFS-2956. calling fetchdt without a --renewer argument throws NPE
+    (vinayakumarb)
+
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/ClientNamenodeProtocolTranslatorPB.java

@@ -927,7 +927,7 @@ public class ClientNamenodeProtocolTranslatorPB implements
       throws IOException {
     GetDelegationTokenRequestProto req = GetDelegationTokenRequestProto
         .newBuilder()
-        .setRenewer(renewer.toString())
+        .setRenewer(renewer == null ? "" : renewer.toString())
         .build();
     try {
       GetDelegationTokenResponseProto resp = rpcProxy.getDelegationToken(null, req);

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/tools/TestDelegationTokenFetcher.java

@@ -16,8 +16,11 @@
  * limitations under the License.
  */
 package org.apache.hadoop.tools;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_DELEGATION_TOKEN_ALWAYS_USE_KEY;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
@@ -32,11 +35,14 @@ import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.FileSystemTestHelper;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.DistributedFileSystem;
+import org.apache.hadoop.hdfs.MiniDFSCluster;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.tools.DelegationTokenFetcher;
 import org.apache.hadoop.io.Text;
+import org.apache.hadoop.security.AccessControlException;
 import org.apache.hadoop.security.Credentials;
 import org.apache.hadoop.security.token.Token;
+import org.apache.hadoop.test.GenericTestUtils;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.invocation.InvocationOnMock;
@@ -108,4 +114,38 @@ public class TestDelegationTokenFetcher {
       fileSys.delete(new Path(tokenFile), true);
     }
   }
+
+  @Test
+  public void testDelegationTokenWithoutRenewer() throws Exception {
+    conf.setBoolean(DFS_NAMENODE_DELEGATION_TOKEN_ALWAYS_USE_KEY, true);
+    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).numDataNodes(0)
+        .build();
+    FileSystem localFs = FileSystem.getLocal(conf);
+    try {
+      cluster.waitActive();
+      DistributedFileSystem fs = cluster.getFileSystem();
+      // Should be able to fetch token without renewer.
+      uri = fs.getUri();
+      DelegationTokenFetcher.main(new String[] { "-fs", uri.toString(),
+          tokenFile });
+      Path p = new Path(localFs.getWorkingDirectory(), tokenFile);
+      Credentials creds = Credentials.readTokenStorageFile(p, conf);
+      Iterator<Token<?>> itr = creds.getAllTokens().iterator();
+      // make sure we got back exactly the 1 token we expected
+      assertTrue(itr.hasNext());
+      assertNotNull("Token without renewer shouldn't be null", itr.next());
+      assertTrue(!itr.hasNext());
+      try {
+        // Without renewer renewal of token should fail.
+        DelegationTokenFetcher.main(new String[] { "--renew", tokenFile });
+        fail("Should have failed to renew");
+      } catch (AccessControlException e) {
+        GenericTestUtils.assertExceptionContains(
+            "tried to renew a token without a renewer", e);
+      }
+    } finally {
+      cluster.shutdown();
+      localFs.delete(new Path(tokenFile), true);
+    }
+  }
 }