6945316: The Win32ShellFolderManager2.isFileSystemRoot can throw NPE

Reviewed-by: alexp

src/windows/classes/sun/awt/shell/Win32ShellFolderManager2.java

@@ -403,9 +403,14 @@ public class Win32ShellFolderManager2 extends ShellFolderManager {
                 }
             }
             String path = dir.getPath();
-            return (path.length() == 3
-                    && path.charAt(1) == ':'
-                    && Arrays.asList(drives.listFiles()).contains(dir));
+
+            if (path.length() != 3 || path.charAt(1) != ':') {
+                return false;
+            }
+
+            File[] files = drives.listFiles();
+
+            return files != null && Arrays.asList(files).contains(dir);
         }
         return false;
     }

test/javax/swing/JFileChooser/6945316/bug6945316.java

+/*
+ * Copyright 2010 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/* @test
+   @bug 6945316
+   @summary The Win32ShellFolderManager2.isFileSystemRoot can throw NPE
+   @author Pavel Porvatov
+   @run main bug6945316
+*/
+
+import sun.awt.OSInfo;
+import sun.awt.shell.ShellFolder;
+
+import java.awt.*;
+import java.io.File;
+import java.util.concurrent.CountDownLatch;
+
+public class bug6945316 {
+    public static void main(String[] args) throws Exception {
+        if (OSInfo.getOSType() != OSInfo.OSType.WINDOWS) {
+            System.out.println("The test is suitable only for Windows OS. Skipped.");
+
+            return;
+        }
+
+        // Init toolkit because it shouldn't be interrupted while initialization
+        Toolkit.getDefaultToolkit();
+
+        // Init the sun.awt.shell.Win32ShellFolderManager2.drives field
+        ShellFolder.get("fileChooserComboBoxFolders");
+
+        // To get NPE the path must obey the following rules:
+        // path.length() == 3 && path.charAt(1) == ':'
+        final File tempFile = new File("c:\\");
+
+        for (int i = 0; i < 10000; i++) {
+            final CountDownLatch countDownLatch = new CountDownLatch(1);
+
+            final Thread thread = new Thread() {
+                public void run() {
+                    countDownLatch.countDown();
+
+                    ShellFolder.isFileSystemRoot(tempFile);
+                }
+            };
+
+            thread.start();
+
+            countDownLatch.await();
+
+            thread.interrupt();
+        }
+    }
+}