HDFS-4156. Seeking to a negative position should throw an IOE. Contributed by Eli Reisman

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1410813 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -250,6 +250,9 @@ Release 2.0.3-alpha - Unreleased
     HDFS-4105. The SPNEGO user for secondary namenode should use the web
     keytab. (Arpit Gupta via jitendra)
 
+    HDFS-4156. Seeking to a negative position should throw an IOE.
+    (Eli Reisman via eli)
+
 Release 2.0.2-alpha - 2012-09-07 
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java

@@ -1076,6 +1076,9 @@ public class DFSInputStream extends FSInputStream implements ByteBufferReadable
     if (targetPos > getFileLength()) {
       throw new IOException("Cannot seek after EOF");
     }
+    if (targetPos < 0) {
+      throw new IOException("Cannot seek to negative offset");
+    }
     if (closed) {
       throw new IOException("Stream is closed!");
     }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSeekBug.java

@@ -141,7 +141,69 @@ public class TestSeekBug {
       cluster.shutdown();
     }
   }
-  
+
+ /**
+  * Test (expected to throw IOE) for negative
+  * <code>FSDataInpuStream#seek</code> argument
+  */
+  @Test (expected=IOException.class)
+  public void testNegativeSeek() throws IOException {
+    Configuration conf = new HdfsConfiguration();
+    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).build();
+    FileSystem fs = cluster.getFileSystem();
+    try {
+      Path seekFile = new Path("seekboundaries.dat");
+      DFSTestUtil.createFile(
+        fs,
+        seekFile,
+        ONEMB,
+        ONEMB,
+        fs.getDefaultBlockSize(seekFile),
+        fs.getDefaultReplication(seekFile),
+        seed);
+      FSDataInputStream stream = fs.open(seekFile);
+      // Perform "safe seek" (expected to pass)
+      stream.seek(65536);
+      assertEquals(65536, stream.getPos());
+      // expect IOE for this call
+      stream.seek(-73);
+    } finally {
+      fs.close();
+      cluster.shutdown();
+    }
+  }
+
+ /**
+  * Test (expected to throw IOE) for <code>FSDataInpuStream#seek</code>
+  * when the position argument is larger than the file size.
+  */
+  @Test (expected=IOException.class)
+  public void testSeekPastFileSize() throws IOException {
+    Configuration conf = new HdfsConfiguration();
+    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).build();
+    FileSystem fs = cluster.getFileSystem();
+    try {
+      Path seekFile = new Path("seekboundaries.dat");
+      DFSTestUtil.createFile(
+        fs,
+        seekFile,
+        ONEMB,
+        ONEMB,
+        fs.getDefaultBlockSize(seekFile),
+        fs.getDefaultReplication(seekFile),
+        seed);
+      FSDataInputStream stream = fs.open(seekFile);
+      // Perform "safe seek" (expected to pass)
+      stream.seek(65536);
+      assertEquals(65536, stream.getPos());
+      // expect IOE for this call
+      stream.seek(ONEMB + ONEMB + ONEMB);
+    } finally {
+      fs.close();
+      cluster.shutdown();
+    }
+  }
+ 
   /**
    * Tests if the seek bug exists in FSDataInputStream in LocalFS.
    */