8153250: java.io.File does not handle Windows paths of the form "D:" (no path) correctly

When resolving a child to a parent, do not insert a file separator for Windows directory-relative paths

Reviewed-by: rriggs

jdk/src/java.base/windows/classes/java/io/WinNTFileSystem.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2017, Oracle and/or its affiliates. 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
@@ -233,11 +233,14 @@ class WinNTFileSystem extends FileSystem {
         int childStart = 0;
         int parentEnd = pn;
 
+        boolean isDirectoryRelative =
+            pn == 2 && isLetter(parent.charAt(0)) && parent.charAt(1) == ':';
+
         if ((cn > 1) && (c.charAt(0) == slash)) {
             if (c.charAt(1) == slash) {
                 /* Drop prefix when child is a UNC pathname */
                 childStart = 2;
-            } else {
+            } else if (!isDirectoryRelative) {
                 /* Drop prefix when child is drive-relative */
                 childStart = 1;
 
@@ -254,7 +257,7 @@ class WinNTFileSystem extends FileSystem {
 
         int strlen = parentEnd + cn - childStart;
         char[] theChars = null;
-        if (child.charAt(childStart) == slash) {
+        if (child.charAt(childStart) == slash || isDirectoryRelative) {
             theChars = new char[strlen];
             parent.getChars(0, parentEnd, theChars, 0);
             child.getChars(childStart, cn, theChars, parentEnd);

jdk/test/java/io/File/WinDirRelative.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2017, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8153250
+ * @summary Tests that files are correctly listed for a directory-relative path
+ * @requires (os.family == "windows")
+ */
+import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
+
+public class WinDirRelative {
+    private static final char COLON = ':';
+    private static final String BASENAME = "TestFile_";
+    private static final String EXTENSION = ".txt";
+    private static final int NUM_FILES = 10;
+
+    private static boolean isLetter(char c) {
+        return ((c >= 'a') && (c <= 'z')) || ((c >= 'A') && (c <= 'Z'));
+    }
+
+    public static void main(String[] args) throws Throwable {
+        // Get the working directory which is also the default
+        // directory for the current drive.
+        String userDir = System.getProperty("user.dir");
+
+        // Test only if a leading drive letter is found
+        if (isLetter(userDir.charAt(0)) && userDir.charAt(1) == COLON) {
+            // Create some empty files
+            List<String> filenames = new ArrayList<String>(NUM_FILES);
+            for (int i = 0; i < NUM_FILES; i++) {
+                String filename = BASENAME + i + EXTENSION;
+                filenames.add(filename);
+                File f = new File(filename);
+                f.createNewFile();
+                f.deleteOnExit();
+                System.out.printf("Created %s (%s)%n", filename,
+                    f.getAbsolutePath());
+            }
+
+            // List files and verify that the ones with recognized names exist.
+            String prefix = userDir.substring(0, 2);
+            File p = new File(prefix);
+            int failures = 0;
+            int successes = 0;
+            for (File f : p.listFiles()) {
+                if (f.getName().toString().startsWith(BASENAME)) {
+                    if (!f.exists()) {
+                        System.err.printf("%s (%s) does not exist%n", f,
+                            f.getAbsolutePath());
+                        failures++;
+                    } else {
+                        successes++;
+                    }
+                }
+            }
+
+            // Fail if there was an existence test failure or if not
+            // enough of the created files were found
+            boolean testFailed = false;
+            if (failures > 0) {
+                System.err.println("Existence check failed");
+                testFailed = true;
+            }
+            if (successes != NUM_FILES) {
+                System.err.println("Count check failed");
+                testFailed = true;
+            }
+            if (testFailed) {
+                throw new RuntimeException("Test failed");
+            }
+        }
+    }
+}