HDFS-4875. Merging change r1493850 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1493854 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -896,6 +896,9 @@ Release 2.1.0-beta - UNRELEASED
     HDFS-4902. DFSClient.getSnapshotDiffReport should use string path rather 
     than o.a.h.fs.Path. (Binglin Chang via jing9) 
 
+    HDFS-4875. Add a test for testing snapshot file length. 
+    (Arpit Agarwal via jing9)
+
 Release 2.0.5-alpha - 06/06/2013
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotFileLength.java

@@ -0,0 +1,115 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.server.namenode.snapshot;
+
+import java.util.Random;
+
+import org.apache.hadoop.fs.FileStatus;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.DFSTestUtil;
+import org.apache.hadoop.hdfs.DistributedFileSystem;
+import org.apache.hadoop.hdfs.MiniDFSCluster;
+
+public class TestSnapshotFileLength {
+
+  private static final long SEED = 0;
+  private static final short REPLICATION = 1;
+  private static final int BLOCKSIZE = 1024;
+
+  private static Configuration conf = new Configuration();
+  private static MiniDFSCluster cluster;
+  private static DistributedFileSystem hdfs;
+
+  private final Path dir = new Path("/TestSnapshotFileLength");
+  private final Path sub = new Path(dir, "sub1");
+  private final String file1Name = "file1";
+  private final String snapshot1 = "snapshot1";
+
+  @Before
+  public void setUp() throws Exception {
+    cluster = new MiniDFSCluster.Builder(conf).numDataNodes(REPLICATION)
+                                              .build();
+    cluster.waitActive();
+    hdfs = cluster.getFileSystem();
+  }
+
+  @After
+  public void tearDown() throws Exception {
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
+  }
+
+
+  /**
+   * Test that we cannot read a file beyond its snapshot length
+   * when accessing it via a snapshot path.
+   *
+   */
+  @Test (timeout=300000)
+  public void testSnapshotfileLength() throws Exception {
+    hdfs.mkdirs(sub);
+
+    int bytesRead;
+    byte[] buffer = new byte[BLOCKSIZE * 8];
+    FSDataInputStream fis = null;
+    FileStatus fileStatus = null;
+
+    // Create and write a file.
+    Path file1 = new Path(sub, file1Name);
+    DFSTestUtil.createFile(hdfs, file1, 0, REPLICATION, SEED);
+    DFSTestUtil.appendFile(hdfs, file1, BLOCKSIZE);
+
+    // Create a snapshot on the parent directory.
+    hdfs.allowSnapshot(sub);
+    hdfs.createSnapshot(sub, snapshot1);
+
+    // Write more data to the file.
+    DFSTestUtil.appendFile(hdfs, file1, BLOCKSIZE);
+
+    // Make sure we can read the entire file via its non-snapshot path.
+    fileStatus = hdfs.getFileStatus(file1);
+    assertThat(fileStatus.getLen(), is((long) BLOCKSIZE * 2));
+    fis = hdfs.open(file1);
+    bytesRead = fis.read(0, buffer, 0, buffer.length);
+    assertThat(bytesRead, is(BLOCKSIZE * 2));
+    fis.close();
+
+    // Try to open the file via its snapshot path.
+    Path file1snap1 =
+        SnapshotTestHelper.getSnapshotPath(sub, snapshot1, file1Name);
+    fis = hdfs.open(file1snap1);
+    fileStatus = hdfs.getFileStatus(file1snap1);
+    assertThat(fileStatus.getLen(), is((long) BLOCKSIZE));
+
+    // Make sure we can only read up to the snapshot length.
+    bytesRead = fis.read(0, buffer, 0, buffer.length);
+    assertThat(bytesRead, is(BLOCKSIZE));
+    fis.close();
+  }
+}