ZOOKEEPER-2249: CRC check failed when preAllocSize smaller than node …

…data

src/java/main/org/apache/zookeeper/server/persistence/Util.java

@@ -211,7 +211,7 @@ public static long padLogFile(FileOutputStream f,long currentSize,
             long preAllocSize) throws IOException{
         long position = f.getChannel().position();
         if (position + 4096 >= currentSize) {
-            currentSize = currentSize + preAllocSize;
+            currentSize = position + preAllocSize;
             fill.position(0);
             f.getChannel().write(fill, currentSize-fill.remaining());
         }

src/java/test/org/apache/zookeeper/test/FileTxnLogPaddingCorruptionTest.java

@@ -0,0 +1,75 @@
+/**
+ * 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.zookeeper.test;
+
+import org.apache.zookeeper.ZKTestCase;
+import org.apache.zookeeper.ZooDefs;
+import org.apache.zookeeper.server.persistence.FileTxnLog;
+import org.apache.zookeeper.txn.CreateTxn;
+import org.apache.zookeeper.txn.TxnHeader;
+import org.junit.Assert;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+
+public class FileTxnLogPaddingCorruptionTest extends ZKTestCase {
+  protected static final Logger LOG = LoggerFactory.getLogger(FileTxnLogPaddingCorruptionTest.class);
+
+  @Test
+  public void testPreAllocSizeSmallerThanTxnData() throws IOException {
+    File logDir = ClientBase.createTmpDir();
+    FileTxnLog fileTxnLog = new FileTxnLog(logDir);
+
+    // Set a small preAllocSize (.5 MB)
+    final int preAllocSize = 500000;
+    fileTxnLog.setPreallocSize(preAllocSize);
+
+    // Create dummy txn larger than preAllocSize + 4KB (the size used in Util#padLogFile to determine if padding is necessary)
+    // Since the file padding inserts a 0, we will fill the data with 0xff to ensure we corrupt the data if we put the 0 in the data
+    byte[] data = new byte[2 * preAllocSize];
+    Arrays.fill(data, (byte) 0xff);
+
+    // Append and commit 2 transactions to the log
+    // Prior to ZOOKEEPER-2249, attempting to pad in association with the second transaction will corrupt the first
+    fileTxnLog.append(new TxnHeader(1, 1, 1, 1, ZooDefs.OpCode.create),
+      new CreateTxn("/testPreAllocSizeSmallerThanTxnData1", data, ZooDefs.Ids.OPEN_ACL_UNSAFE, false, 0));
+    fileTxnLog.commit();
+    fileTxnLog.append(new TxnHeader(1, 1, 2, 2, ZooDefs.OpCode.create),
+      new CreateTxn("/testPreAllocSizeSmallerThanTxnData2", new byte[]{}, ZooDefs.Ids.OPEN_ACL_UNSAFE, false, 0));
+    fileTxnLog.commit();
+    fileTxnLog.close();
+
+    // Read the log back from disk, this will throw a java.io.IOException: CRC check failed prior to ZOOKEEPER-2249
+    FileTxnLog.FileTxnIterator fileTxnIterator = new FileTxnLog.FileTxnIterator(logDir, 0);
+
+    // Verify the data in the first transaction
+    CreateTxn createTxn = (CreateTxn) fileTxnIterator.getTxn();
+    Assert.assertTrue(Arrays.equals(createTxn.getData(), data));
+
+    // Verify the data in the second transaction
+    fileTxnIterator.next();
+    createTxn = (CreateTxn) fileTxnIterator.getTxn();
+    Assert.assertTrue(Arrays.equals(createTxn.getData(), new byte[]{}));
+  }
+
+}