From 85c0cb00750fddae1a230974d001908cb70b101b Mon Sep 17 00:00:00 2001
From: cnauroth <cnauroth@apache.org>
Date: Fri, 25 Sep 2015 22:33:53 -0700
Subject: [PATCH] HADOOP-11918. Listing an empty s3a root directory throws
 FileNotFound. Contributed by Lei (Eddy) Xu.

(cherry picked from commit 7fe521b1dd49f81ae325f78cf531cfff15be6641)
---
 hadoop-common-project/hadoop-common/CHANGES.txt    |  3 +++
 .../AbstractContractRootDirectoryTest.java         | 14 ++++++++++++++
 .../org/apache/hadoop/fs/s3a/S3AFileSystem.java    |  3 +++
 3 files changed, 20 insertions(+)

diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 513d377835c..36418825a5a 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -582,6 +582,9 @@ Release 2.8.0 - UNRELEASED
     HADOOP-12252. LocalDirAllocator should not throw NPE with empty string
     configuration. (Zhihai Xu)
 
+    HADOOP-11918. Listing an empty s3a root directory throws FileNotFound.
+    (Lei (Eddy) Xu via cnauroth)
+
   OPTIMIZATIONS
 
     HADOOP-12051. ProtobufRpcEngine.invoke() should use Exception.toString()
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/contract/AbstractContractRootDirectoryTest.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/contract/AbstractContractRootDirectoryTest.java
index 83d9143e77d..fb1455e618f 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/contract/AbstractContractRootDirectoryTest.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/contract/AbstractContractRootDirectoryTest.java
@@ -25,6 +25,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import org.apache.hadoop.fs.FileStatus;
 
 import static org.apache.hadoop.fs.contract.ContractTestUtils.createFile;
 import static org.apache.hadoop.fs.contract.ContractTestUtils.dataset;
@@ -120,4 +121,17 @@ public abstract class AbstractContractRootDirectoryTest extends AbstractFSContra
     assertIsDirectory(root);
   }
 
+  @Test
+  public void testListEmptyRootDirectory() throws IOException {
+    //extra sanity checks here to avoid support calls about complete loss of data
+    skipIfUnsupported(TEST_ROOT_TESTS_ENABLED);
+    FileSystem fs = getFileSystem();
+    Path root = new Path("/");
+    FileStatus[] statuses = fs.listStatus(root);
+    for (FileStatus status : statuses) {
+      ContractTestUtils.assertDeleted(fs, status.getPath(), true);
+    }
+    assertEquals("listStatus on empty root-directory returned a non-empty list",
+        0, fs.listStatus(root).length);
+  }
 }
diff --git a/hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java b/hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java
index f9e937f8f4d..83be18423fe 100644
--- a/hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java
+++ b/hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java
@@ -983,6 +983,9 @@ public class S3AFileSystem extends FileSystem {
 
         return new S3AFileStatus(true, false,
             f.makeQualified(uri, workingDir));
+      } else if (key.isEmpty()) {
+        LOG.debug("Found root directory");
+        return new S3AFileStatus(true, true, f.makeQualified(uri, workingDir));
       }
     } catch (AmazonServiceException e) {
       if (e.getStatusCode() != 404) {