From 61bf9cae6f3882c6e9a9222f59457b9be91e3018 Mon Sep 17 00:00:00 2001
From: Karthik Kambatla <kasha@apache.org>
Date: Sat, 22 Aug 2015 00:38:47 -0700
Subject: [PATCH] MAPREDUCE-6455. Unable to use surefire > 2.18. (Charlie Helin
 via kasha)

---
 .../main/java/org/apache/hadoop/conf/Configuration.java  | 9 +++++++--
 hadoop-mapreduce-project/CHANGES.txt                     | 2 ++
 .../src/main/java/org/apache/hadoop/mapred/TaskLog.java  | 4 +++-
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
index 0b4542966c4..6f1d3f8f79d 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
@@ -988,8 +988,13 @@ private String substituteVars(String expr) {
       } catch(SecurityException se) {
         LOG.warn("Unexpected SecurityException in Configuration", se);
       }
-      if (val == null) {
-        val = getRaw(var);
+      if (val == null || val.isEmpty()) {
+        String raw = getRaw(var);
+        if (raw != null) {
+          // if System.getProperty(var) returns an empty string, retain this
+          // value instead of return null
+          val = raw;
+        }
       }
       if (val == null) {
         return eval; // return literal ${var}: var is unbound
diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index 361a19b6953..305b29e793a 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -275,6 +275,8 @@ Trunk (Unreleased)
     MAPREDUCE-5801. Uber mode's log message is missing a vcore reason
     (Steven Wong via aw)
 
+    MAPREDUCE-6455. Unable to use surefire > 2.18. (Charlie Helin via kasha)
+
 Release 2.8.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/TaskLog.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/TaskLog.java
index e07b5be2870..b8bb2f2a924 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/TaskLog.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/TaskLog.java
@@ -181,7 +181,9 @@ static String obtainLogDirOwner(TaskAttemptID taskid) throws IOException {
   }
 
   static String getBaseLogDir() {
-    return System.getProperty("hadoop.log.dir");
+    String logDir = System.getProperty("hadoop.log.dir");
+    // file is treating "" different from null {@see File#File(String, String)}
+    return logDir == null || logDir.isEmpty() ? null : logDir;
   }
 
   static File getAttemptDir(TaskAttemptID taskid, boolean isCleanup) {