From c79710302ee51e1a9ee17dadb161c69bb3aba5c9 Mon Sep 17 00:00:00 2001
From: Haohui Mai <wheat9@apache.org>
Date: Fri, 6 Mar 2015 14:26:23 -0800
Subject: [PATCH] HDFS-7818. OffsetParam should return the default value
 instead of throwing NPE when the value is unspecified. Contributed by Eric
 Payne.

---
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt   |  3 +++
 .../datanode/web/webhdfs/ParameterParser.java |  2 +-
 .../hdfs/web/resources/OffsetParam.java       |  5 +++++
 .../web/webhdfs/TestParameterParser.java      | 19 +++++++++++++++++++
 4 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index e622a57ef99..b443902f3c7 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -1107,6 +1107,9 @@ Release 2.7.0 - UNRELEASED
     HDFS-7885. Datanode should not trust the generation stamp provided by
     client. (Tsz Wo Nicholas Sze via jing9)
 
+    HDFS-7818. OffsetParam should return the default value instead of throwing
+    NPE when the value is unspecified. (Eric Payne via wheat9)
+
     BREAKDOWN OF HDFS-7584 SUBTASKS AND RELATED JIRAS
 
       HDFS-7720. Quota by Storage Type API, tools and ClientNameNode
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/ParameterParser.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/ParameterParser.java
index 57495046899..2baafe8f29c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/ParameterParser.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/ParameterParser.java
@@ -62,7 +62,7 @@ String op() {
   }
 
   long offset() {
-    return new OffsetParam(param(OffsetParam.NAME)).getValue();
+    return new OffsetParam(param(OffsetParam.NAME)).getOffset();
   }
 
   String namenodeId() {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/OffsetParam.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/OffsetParam.java
index 6973787847d..6d88703da0a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/OffsetParam.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/OffsetParam.java
@@ -46,4 +46,9 @@ public OffsetParam(final String str) {
   public String getName() {
     return NAME;
   }
+
+  public Long getOffset() {
+    Long offset = getValue();
+    return (offset == null) ? Long.valueOf(0) : offset;
+  }
 }
\ No newline at end of file
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestParameterParser.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestParameterParser.java
index 6a6c5d05d9b..8aee1d8565c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestParameterParser.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestParameterParser.java
@@ -23,6 +23,7 @@
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.web.resources.DelegationParam;
 import org.apache.hadoop.hdfs.web.resources.NamenodeAddressParam;
+import org.apache.hadoop.hdfs.web.resources.OffsetParam;
 import org.apache.hadoop.security.token.Token;
 import org.junit.Assert;
 import org.junit.Test;
@@ -65,4 +66,22 @@ public void testDecodePath() {
     ParameterParser testParser = new ParameterParser(decoder, conf);
     Assert.assertEquals(EXPECTED_PATH, testParser.path());
   }
+
+  @Test
+  public void testOffset() throws IOException {
+    final long X = 42;
+
+    long offset = new OffsetParam(Long.toString(X)).getOffset();
+    Assert.assertEquals("OffsetParam: ", X, offset);
+
+    offset = new OffsetParam((String) null).getOffset();
+    Assert.assertEquals("OffsetParam with null should have defaulted to 0", 0, offset);
+
+    try {
+      offset = new OffsetParam("abc").getValue();
+      Assert.fail("OffsetParam with nondigit value should have thrown IllegalArgumentException");
+    } catch (IllegalArgumentException iae) {
+      // Ignore
+    }
+  }
 }