HDFS-2359. Fix NullPointerException in DataBlockScanner. Contributed by Jonthan Eagles.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20-security-205@1176042 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -211,6 +211,9 @@ Release 0.20.205.0 - 2011.09.12
 
     HADOOP-7676. Enable hbase to run as hdfs user (gkesavan)
 
+    HDFS-2359. Fix NullPointerException in DataBlockScanner.
+    (Jonthan Eagles via suresh)
+
   IMPROVEMENTS
 
     MAPREDUCE-2928. MR-2413 improvements (Eli Collins via mattf)

src/hdfs/org/apache/hadoop/hdfs/server/datanode/DataBlockScanner.java

@@ -785,6 +785,9 @@ class DataBlockScanner implements Runnable {
      * return true if append was successful.
      */
     synchronized boolean appendLine(String line) {
+      if (out == null) {
+        return false;
+      }
       out.println();
       out.print(line);
       curNumLines += (curNumLines < 0) ? -1 : 1;