HDFS-12948. DiskBalancer report command top option should only take positive numeric values. Contributed by Shashikant Banerjee.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/command/Command.java

@@ -501,7 +501,8 @@ public abstract class Command extends Configured implements Closeable {
    * Parse top number of nodes to be processed.
    * @return top number of nodes to be processed.
    */
-  protected int parseTopNodes(final CommandLine cmd, final StrBuilder result) {
+  protected int parseTopNodes(final CommandLine cmd, final StrBuilder result)
+      throws IllegalArgumentException {
     String outputLine = "";
     int nodes = 0;
     final String topVal = cmd.getOptionValue(DiskBalancerCLI.TOP);
@@ -523,6 +524,10 @@ public abstract class Command extends Configured implements Closeable {
         result.appendln(outputLine);
         nodes = getDefaultTop();
       }
+      if (nodes <= 0) {
+        throw new IllegalArgumentException(
+            "Top limit input should be a positive numeric value");
+      }
     }
 
     return Math.min(nodes, cluster.getNodes().size());

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/command/ReportCommand.java

@@ -100,7 +100,7 @@ public class ReportCommand extends Command {
   }
 
   private void handleTopReport(final CommandLine cmd, final StrBuilder result,
-      final String nodeFormat) {
+      final String nodeFormat) throws IllegalArgumentException {
     Collections.sort(getCluster().getNodes(), Collections.reverseOrder());
 
     /* extract value that identifies top X DataNode(s) */

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/diskbalancer/command/TestDiskBalancerCommand.java

@@ -244,6 +244,15 @@ public class TestDiskBalancerCommand {
 
   }
 
+  /* test basic report with negative top limit */
+  @Test(timeout = 60000)
+  public void testReportWithNegativeTopLimit()
+      throws Exception {
+    final String cmdLine = "hdfs diskbalancer -report -top -32";
+    thrown.expect(java.lang.IllegalArgumentException.class);
+    thrown.expectMessage("Top limit input should be a positive numeric value");
+    runCommand(cmdLine);
+  }
   /* test less than 64 DataNode(s) as total, e.g., -report -top 32 */
   @Test(timeout = 60000)
   public void testReportLessThanTotal() throws Exception {