HADOOP-6531. Enhance FileUtil with an API to delete all contents of a directory. Contributed by Amareshwari Sriramadasu.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@906177 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -125,6 +125,9 @@ Trunk (unreleased changes)
     HADOOP-6518. Makes the UGI honor the env var KRB5CCNAME. 
     (Owen O'Malley via ddas)
 
+    HADOOP-6531. Enhance FileUtil with an API to delete all contents of a
+    directory. (Amareshwari Sriramadasu via yhemanth)
+
   OPTIMIZATIONS
 
   BUG FIXES

src/java/org/apache/hadoop/fs/FileUtil.java

@@ -71,6 +71,17 @@ public static Path[] stat2Paths(FileStatus[] stats, Path path) {
    * we return false, the directory may be partially-deleted.
    */
   public static boolean fullyDelete(File dir) throws IOException {
+    if (!fullyDeleteContents(dir)) {
+      return false;
+    }
+    return dir.delete();
+  }
+
+  /**
+   * Delete the contents of a directory, not the directory itself.  If
+   * we return false, the directory may be partially-deleted.
+   */
+  public static boolean fullyDeleteContents(File dir) throws IOException {
     File contents[] = dir.listFiles();
     if (contents != null) {
       for (int i = 0; i < contents.length; i++) {
@@ -95,7 +106,7 @@ public static boolean fullyDelete(File dir) throws IOException {
         }
       }
     }
-    return dir.delete();
+    return true;
   }
 
   /**

src/test/core/org/apache/hadoop/fs/TestFileUtil.java

@@ -0,0 +1,154 @@
+/**
+ * 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.hadoop.fs;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class TestFileUtil {
+  final static private File TEST_DIR = new File(System.getProperty(
+      "test.build.data", "/tmp"), "fu");
+  private static String FILE = "x";
+  private static String LINK = "y";
+  private static String DIR = "dir";
+  private File del = new File(TEST_DIR, "del");
+  private File tmp = new File(TEST_DIR, "tmp");
+  private File dir1 = new File(del, DIR + "1");
+  private File dir2 = new File(del, DIR + "2");
+
+  /**
+   * Creates directories del and tmp for testing.
+   * 
+   * Contents of them are
+   * dir:tmp: 
+   *   file: x
+   * dir:del:
+   *   file: x
+   *   dir: dir1 : file:x
+   *   dir: dir2 : file:x
+   *   link: y to tmp/x
+   *   link: tmpDir to tmp
+   */
+  private void setupDirs() throws IOException {
+    Assert.assertFalse(del.exists());
+    Assert.assertFalse(tmp.exists());
+    del.mkdirs();
+    tmp.mkdirs();
+    new File(del, FILE).createNewFile();
+    File tmpFile = new File(tmp, FILE);
+    tmpFile.createNewFile();
+
+    // create directories 
+    dir1.mkdirs();
+    dir2.mkdirs();
+    new File(dir1, FILE).createNewFile();
+    new File(dir2, FILE).createNewFile();
+
+    // create a symlink to file
+    File link = new File(del, LINK);
+    FileUtil.symLink(tmpFile.toString(), link.toString());
+
+    // create a symlink to dir
+    File linkDir = new File(del, "tmpDir");
+    FileUtil.symLink(tmp.toString(), linkDir.toString());
+    Assert.assertEquals(5, del.listFiles().length);
+  }
+
+  @After
+  public void tearDown() throws IOException {
+    FileUtil.fullyDelete(del);
+    FileUtil.fullyDelete(tmp);
+  }
+
+  @Test
+  public void testFullyDelete() throws IOException {
+    setupDirs();
+    boolean ret = FileUtil.fullyDelete(del);
+    Assert.assertTrue(ret);
+    Assert.assertFalse(del.exists());
+    validateTmpDir();
+  }
+
+  @Test
+  public void testFullyDeleteContents() throws IOException {
+    setupDirs();
+    boolean ret = FileUtil.fullyDeleteContents(del);
+    Assert.assertTrue(ret);
+    Assert.assertTrue(del.exists());
+    Assert.assertEquals(0, del.listFiles().length);
+    validateTmpDir();
+  }
+
+  private void validateTmpDir() {
+    Assert.assertTrue(tmp.exists());
+    Assert.assertEquals(1, tmp.listFiles().length);
+    Assert.assertTrue(new File(tmp, FILE).exists());
+  }
+  
+  /**
+   * Creates a directory which can not be deleted.
+   * 
+   * Contents of the directory are :
+   * dir : del
+   *   dir : dir1 : x. this directory is not writable
+   * @throws IOException
+   */
+  private void setupDirsAndNonWritablePermissions() throws IOException {
+    Assert.assertFalse(del.exists());
+    del.mkdirs();
+    new File(del, FILE).createNewFile();
+
+    // create directory 
+    dir1.mkdirs();
+    new File(dir1, FILE).createNewFile();
+    changePermissions(false);
+  }
+  
+  // sets writable permissions for dir1
+  private void changePermissions(boolean perm) {
+    dir1.setWritable(perm);
+  }
+
+  // validates the return value
+  // validates the directory:dir1 exists
+  // sets writable permissions for the directory so that it can be deleted in 
+  // tearDown() 
+  private void validateAndSetWritablePermissions(boolean ret) {
+    Assert.assertFalse(ret);
+    Assert.assertTrue(dir1.exists());
+    changePermissions(true);
+  }
+  
+  @Test
+  public void testFailFullyDelete() throws IOException {
+    setupDirsAndNonWritablePermissions();
+    boolean ret = FileUtil.fullyDelete(del);
+    validateAndSetWritablePermissions(ret);
+  }
+
+  @Test
+  public void testFailFullyDeleteContents() throws IOException {
+    setupDirsAndNonWritablePermissions();
+    boolean ret = FileUtil.fullyDeleteContents(del);
+    validateAndSetWritablePermissions(ret);
+  }
+}