HADOOP-18621. Resource leak in CryptoOutputStream.close() (#5347)

When closing we need to wrap the flush() in a try .. finally, otherwise
when flush throws it will stop completion of the remainder of the
close activities and in particular the close of the underlying wrapped
stream object resulting in a resource leak.

Contributed by Colm Dougan

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/crypto/CryptoOutputStream.java

@@ -240,13 +240,16 @@ public synchronized void close() throws IOException {
     if (closed) {
       return;
     }
+    try {
       try {
         flush();
+      } finally {
         if (closeOutputStream) {
           super.close();
           codec.close();
         }
         freeBuffers();
+      }
     } finally {
       closed = true;
     }

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/crypto/TestCryptoOutputStreamClosing.java

@@ -17,12 +17,14 @@
  */
 package org.apache.hadoop.crypto;
 
+import java.io.IOException;
 import java.io.OutputStream;
 
 import org.apache.hadoop.conf.Configuration;
 
 import org.junit.BeforeClass;
 import org.junit.Test;
+import static org.apache.hadoop.test.LambdaTestUtils.intercept;
 import static org.mockito.Mockito.*;
 
 /**
@@ -54,4 +56,22 @@ public void testOutputStreamNotClosing() throws Exception {
     verify(outputStream, never()).close();
   }
 
+  @Test
+  public void testUnderlyingOutputStreamClosedWhenExceptionClosing() throws Exception {
+    OutputStream outputStream = mock(OutputStream.class);
+    CryptoOutputStream cos = spy(new CryptoOutputStream(outputStream, codec,
+        new byte[16], new byte[16], 0L, true));
+
+    // exception while flushing during close
+    doThrow(new IOException("problem flushing wrapped stream"))
+        .when(cos).flush();
+
+    intercept(IOException.class,
+        () -> cos.close());
+
+    // We expect that the close of the CryptoOutputStream closes the
+    // wrapped OutputStream even though we got an exception
+    // during CryptoOutputStream::close (in the flush method)
+    verify(outputStream).close();
+  }
 }