HADOOP-17907. FileUtil#fullyDelete deletes contents of sym-linked directory when symlink cannot be deleted because of local fs fault (#3431). Contributed by Weihao Zheng.

Signed-off-by: Ayush Saxena <ayushsaxena@apache.org>

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileUtil.java

@@ -58,6 +58,7 @@ import java.util.zip.ZipInputStream;
 import org.apache.commons.collections.map.CaseInsensitiveMap;
 import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
 import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
+import org.apache.commons.io.FileUtils;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.Configuration;
@@ -182,7 +183,7 @@ public class FileUtil {
       return true;
     }
     // handle nonempty directory deletion
-    if (!fullyDeleteContents(dir, tryGrantPermissions)) {
+    if (!FileUtils.isSymlink(dir) && !fullyDeleteContents(dir, tryGrantPermissions)) {
       return false;
     }
     return deleteImpl(dir, true);

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestFileUtil.java

@@ -447,6 +447,35 @@ public class TestFileUtil {
     validateAndSetWritablePermissions(false, ret);
   }
 
+
+  /**
+   * Tests if fullyDelete deletes symlink's content when deleting unremovable dir symlink.
+   * @throws IOException
+   */
+  @Test (timeout = 30000)
+  public void testFailFullyDeleteDirSymlinks() throws IOException {
+    File linkDir = new File(del, "tmpDir");
+    FileUtil.setWritable(del, false);
+    // Since tmpDir is symlink to tmp, fullyDelete(tmpDir) should not
+    // delete contents of tmp. See setupDirs for details.
+    boolean ret = FileUtil.fullyDelete(linkDir);
+    // fail symlink deletion
+    Assert.assertFalse(ret);
+    Assert.assertTrue(linkDir.exists());
+    Assert.assertEquals(5, del.list().length);
+    // tmp dir should exist
+    validateTmpDir();
+    // simulate disk recovers and turns good
+    FileUtil.setWritable(del, true);
+    ret = FileUtil.fullyDelete(linkDir);
+    // success symlink deletion
+    Assert.assertTrue(ret);
+    Assert.assertFalse(linkDir.exists());
+    Assert.assertEquals(4, del.list().length);
+    // tmp dir should exist
+    validateTmpDir();
+  }
+
   /**
    * Extend {@link File}. Same as {@link File} except for two things: (1) This
    * treats file1Name as a very special file which is not delete-able