[FIXED JENKINS-20630]

The size is in wchar_t, not in bytes

changelog.html

@@ -75,6 +75,9 @@ Upcoming changes</a>
   <li class="major rfe">
     Allow build queue and executor status panes to be collapsed.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-5622">issue 5622</a>)
+  <li class="major bug">
+    Jenkins 1.540 just doesn't boot on Windows at all.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-26030">issue 26030</a>)
 </ul>
 </div><!--=END=-->
 <h3><a name=v1.541>What's new in 1.541</a> (2013/11/24)</h3>

core/src/main/java/hudson/util/jna/Kernel32Utils.java

@@ -100,7 +100,7 @@ public class Kernel32Utils {
 
     public static File getTempDir() {
         Memory buf = new Memory(1024);
-        if (Kernel32.INSTANCE.GetTempPathW(1024,buf)!=0) {
+        if (Kernel32.INSTANCE.GetTempPathW(512,buf)!=0) {// the first arg is number of wchar
             return new File(buf.getString(0, true));
         } else {
             return null;