--- /dev/null	2018-06-17 23:18:20.806999507 +0800
+++ new/test/lib/testlibrary/jdk/testlibrary/jfr/FileHelper.java	2019-01-29 11:06:00.404441673 +0800
@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2013, 2019, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+package jdk.testlibrary.jfr;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.AccessDeniedException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+
+import jdk.jfr.consumer.RecordedEvent;
+import jdk.jfr.consumer.RecordingFile;
+import jdk.testlibrary.Asserts;
+
+/**
+ * Common helper class.
+ */
+public class FileHelper {
+
+    public static Path getDest(String subPath) throws IOException {
+        Path path = Paths.get(subPath + "/test.jfr");
+        Path parent = path.getParent();
+        if (parent == null) {
+            throw new IOException("No parent cound be found for path " + subPath);
+        }
+        Files.createDirectories(parent);
+        return path;
+    }
+
+    public static Path createLongDir(Path root) throws IOException {
+        final int minPathLength = 400;
+        StringBuilder buff = new StringBuilder();
+        buff.append(root.toString());
+        while (buff.length() < minPathLength) {
+            buff.append("/veryLongPath012345678901234567890123456789");
+        }
+        Path path = Paths.get(buff.toString());
+        System.out.println("long dir=" + path);
+        Files.createDirectories(path);
+        return path;
+    }
+
+    public static Path getDestReadOnly(String subPath) throws IOException {
+        final Path path = getDest(subPath);
+        Path parent = path.getParent();
+        if (parent == null) {
+            throw new IOException("No parent cound be found for path " + subPath);
+        }
+        parent.toFile().setReadOnly();
+        return path;
+    }
+
+    public static Path createReadOnlyFile(Path path) throws IOException {
+        final Path createdPath = Files.createFile(path);
+        createdPath.toFile().setReadOnly();
+        return createdPath;
+    }
+
+    public static Path createReadOnlyDir(Path path) throws IOException {
+        final Path createdPath = Files.createDirectories(path);
+        createdPath.toFile().setReadOnly();
+        return createdPath;
+    }
+
+    public static Path getDestNotExist() {
+        return Paths.get(".", "thisDirDoesNotExist/test.jfr");
+    }
+
+    public static boolean isReadOnlyPath(Path path) throws IOException {
+        // Files.isWritable(path) can not really be trusted. At least not on Windows.
+        // If path is a directory, we try to create a new file in it.
+        if (Files.isDirectory(path)) {
+            try {
+                Path f = Files.createFile(Paths.get(path.toString(), "dummyFileToCheckReadOnly"));
+                System.out.printf("Dir is not read-only, created %s, exists=%b%n", f, Files.exists(f));
+                return false;
+            } catch (AccessDeniedException e) {
+                System.out.printf("'%s' verified read-only by %s%n", path, e.toString());
+                return true;
+            }
+        } else {
+            boolean isReadOnly = !Files.isWritable(path);
+            System.out.format("isReadOnly '%s': %b%n", path, isReadOnly);
+            return isReadOnly;
+        }
+    }
+
+    public static void verifyRecording(File file) throws Exception {
+        Asserts.assertTrue(file.exists(), file.getAbsolutePath() + " does not exist");
+        Asserts.assertTrue(file.isFile(), file.getAbsolutePath() + " is not a file");
+        Asserts.assertGreaterThan(file.length(), 0L, "Size of recording is 0.");
+        List<RecordedEvent> events = RecordingFile.readAllEvents(file.toPath());
+        for (RecordedEvent event : events) {
+            System.out.printf("First event in recording '%s':%n%s", file.getName(), event);
+            return;
+        }
+        Asserts.fail("No events in file " + file.getName());
+    }
+
+}