isSymbolicLink throws a NPE if invoked for the file system root

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@935069 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/util/SymbolicLinkUtils.java

@@ -64,7 +64,7 @@ public class SymbolicLinkUtils {
      * canonical and absolute paths of the file are identical--this
      * may lead to false positives on some platforms.</p>
      *
-     * @param file the file to test.
+     * @param file the file to test.  Must not be null.
      *
      * @return true if the file is a symbolic link.
      * @throws IOException on error.
@@ -104,7 +104,9 @@ public class SymbolicLinkUtils {
      */
     public boolean isSymbolicLink(File parent, String name)
         throws IOException {
-        File toTest = new File(parent.getCanonicalPath(), name);
+        File toTest = parent != null
+            ? new File(parent.getCanonicalPath(), name)
+            : new File(name);
         return !toTest.getAbsolutePath().equals(toTest.getCanonicalPath());
     }
 

src/tests/junit/org/apache/tools/ant/util/SymlinkUtilsTest.java

@@ -0,0 +1,33 @@
+/*
+ *  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.tools.ant.util;
+
+import java.io.IOException;
+import junit.framework.TestCase;
+
+public class SymlinkUtilsTest extends TestCase {
+
+    private static final SymbolicLinkUtils SYMLINK_UTILS =
+        SymbolicLinkUtils.getSymbolicLinkUtils();
+
+    public void testRootIsNoSymlink() throws IOException {
+        assertFalse(SYMLINK_UTILS.isSymbolicLink("/"));
+    }
+
+}