HDFS-13539. DFSStripedInputStream NPE when reportCheckSumFailure.

(cherry picked from commit 960940e0e08f7839775f2d8a352b444d104d36b4)

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java

@@ -790,13 +790,24 @@ public class DFSInputStream extends FSInputStream
           // Check if need to report block replicas corruption either read
           // was successful or ChecksumException occurred.
           reportCheckSumFailure(corruptedBlocks,
-              currentLocatedBlock.getLocations().length, false);
+              getCurrentBlockLocationsLength(), false);
         }
       }
     }
     return -1;
   }
 
+  protected int getCurrentBlockLocationsLength() {
+    int len = 0;
+    if (currentLocatedBlock == null) {
+      DFSClient.LOG.info("Found null currentLocatedBlock. pos={}, "
+          + "blockEnd={}, fileLength={}", pos, blockEnd, getFileLength());
+    } else {
+      len = currentLocatedBlock.getLocations().length;
+    }
+    return len;
+  }
+
   /**
    * Read the entire buffer.
    */

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java

@@ -17,6 +17,7 @@
  */
 package org.apache.hadoop.hdfs;
 
+import com.google.common.annotations.VisibleForTesting;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.fs.ReadOption;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
@@ -158,7 +159,8 @@ public class DFSStripedInputStream extends DFSInputStream {
    * When seeking into a new block group, create blockReader for each internal
    * block in the group.
    */
-  private synchronized void blockSeekTo(long target) throws IOException {
+  @VisibleForTesting
+  synchronized void blockSeekTo(long target) throws IOException {
     if (target >= getFileLength()) {
       throw new IOException("Attempted to read past end of file");
     }
@@ -398,8 +400,8 @@ public class DFSStripedInputStream extends DFSInputStream {
       } finally {
         // Check if need to report block replicas corruption either read
         // was successful or ChecksumException occurred.
-        reportCheckSumFailure(corruptedBlocks,
-            currentLocatedBlock.getLocations().length, true);
+        reportCheckSumFailure(corruptedBlocks, getCurrentBlockLocationsLength(),
+            true);
       }
     }
     return -1;

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStripedInputStream.java

@@ -35,6 +35,7 @@ import org.apache.hadoop.io.erasurecode.ErasureCodeNative;
 import org.apache.hadoop.io.erasurecode.ErasureCoderOptions;
 import org.apache.hadoop.io.erasurecode.rawcoder.NativeRSRawErasureCoderFactory;
 import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureDecoder;
+import org.apache.hadoop.test.GenericTestUtils;
 import org.junit.After;
 import org.junit.Assert;
 import org.junit.Before;
@@ -51,7 +52,12 @@ import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.IO_FILE_BUFFER_
 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.IO_FILE_BUFFER_SIZE_KEY;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.mockito.Matchers.anyLong;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.spy;
 
 public class TestDFSStripedInputStream {
 
@@ -504,4 +510,23 @@ public class TestDFSStripedInputStream {
       in.close();
     }
   }
+
+  @Test
+  public void testReadFailToGetCurrentBlock() throws Exception {
+    DFSTestUtil.writeFile(cluster.getFileSystem(), filePath, "test");
+    try (DFSStripedInputStream in = (DFSStripedInputStream) fs.getClient()
+        .open(filePath.toString())) {
+      final DFSStripedInputStream spy = spy(in);
+      final String msg = "Injected exception for testReadNPE";
+      doThrow(new IOException(msg)).when(spy).blockSeekTo(anyLong());
+      assertNull(in.getCurrentBlock());
+      try {
+        spy.read();
+        fail("read should have failed");
+      } catch (IOException expected) {
+        LOG.info("Exception caught", expected);
+        GenericTestUtils.assertExceptionContains(msg, expected);
+      }
+    }
+  }
 }