From 1d2bca87e911c73f0754855ad9ebc93ec9bbfb2c Mon Sep 17 00:00:00 2001
From: Martin Kleppmann <martin@rapportive.com>
Date: Sat, 2 Jun 2012 01:06:47 -0700
Subject: [PATCH] Fix NPE in listing read-only store versions

ReadOnlyUtils.getVersionDirs returns null if storeDir does not exist. I don't yet know how it could get into a state where it thinks the directory doesn't exist, but the NPE is obscuring the actual cause, so I'm fixing that first.
---
 src/java/voldemort/store/readonly/ReadOnlyStorageEngine.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/java/voldemort/store/readonly/ReadOnlyStorageEngine.java b/src/java/voldemort/store/readonly/ReadOnlyStorageEngine.java
index 40f229c275..71faa3e40a 100644
--- a/src/java/voldemort/store/readonly/ReadOnlyStorageEngine.java
+++ b/src/java/voldemort/store/readonly/ReadOnlyStorageEngine.java
@@ -350,7 +350,7 @@ public void swapFiles(String newStoreDirectory) {
      */
     private void deleteBackups() {
         File[] storeDirList = ReadOnlyUtils.getVersionDirs(storeDir, 0L, currentVersionId);
-        if(storeDirList.length > (numBackups + 1)) {
+        if(storeDirList != null && storeDirList.length > (numBackups + 1)) {
             // delete ALL old directories asynchronously
             File[] extraBackups = ReadOnlyUtils.findKthVersionedDir(storeDirList,
                                                                     0,
@@ -424,7 +424,7 @@ public void rollback(File rollbackToDir) {
                 throw new VoldemortException("Cannot parse version id");
 
             File[] backUpDirs = ReadOnlyUtils.getVersionDirs(storeDir, versionId, Long.MAX_VALUE);
-            if(backUpDirs.length <= 1) {
+            if(backUpDirs == null || backUpDirs.length <= 1) {
                 logger.warn("No rollback performed since there are no back-up directories");
                 return;
             }