fixed #585 "Hudson follows symlinks when deleting"

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@3474 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/Util.java

@@ -143,10 +143,40 @@ public class Util {
     }
 
     public static void deleteRecursive(File dir) throws IOException {
-        deleteContentsRecursive(dir);
+        if(!isSymlink(dir))
+            deleteContentsRecursive(dir);
         deleteFile(dir);
     }
 
+    /*
+     * Copyright 2001-2004 The Apache Software Foundation.
+     *
+     * Licensed 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.
+     */
+    /**
+     * Checks if the given file represents a symlink.
+     */
+    //Taken from http://svn.apache.org/viewvc/maven/shared/trunk/file-management/src/main/java/org/apache/maven/shared/model/fileset/util/FileSetManager.java?view=markup
+    public boolean isSymlink(File file) throws IOException {
+        File parent = file.getParentFile();
+        File canonicalFile = file.getCanonicalFile();
+
+        return parent != null
+            && (!canonicalFile.getName().equals(file.getName()) || !canonicalFile.getPath().startsWith(
+            parent.getCanonicalPath()));
+    }
+
+
     /**
      * Creates a new temporary directory.
      */