--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/WriteableUserPath.java	Tue May 15 20:24:34 2018 +0200
@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2016, 2018, 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.jfr.internal;
+
+import java.io.BufferedWriter;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.security.AccessControlContext;
+import java.security.AccessController;
+import java.security.PrivilegedExceptionAction;
+import java.util.concurrent.Callable;
+
+/**
+ * Purpose of this class is to simplify analysis of security risks.
+ * <p>
+ * Paths in the public API should be wrapped in this class so we
+ * at all time know what kind of paths we are dealing with.
+ * <p>
+ * A user supplied path must never be used in an unsafe context, such as a
+ * shutdown hook or any other thread created by JFR.
+ * <p>
+ * All operation using this path must happen in {@link #doPriviligedIO(Callable)}
+ */
+public final class WriteableUserPath {
+    private final AccessControlContext controlContext;
+    private final Path original;
+    private final Path real;
+    private final String text;
+
+    // Not to ensure security, but to help
+    // against programming errors
+    private volatile boolean inPrivileged;
+
+    public WriteableUserPath(Path path) throws IOException {
+        controlContext = AccessController.getContext();
+        // verify that the path is writeable
+        if (Files.exists(path) && !Files.isWritable(path)) {
+            // throw same type of exception as FileOutputStream
+            // constructor, if file can't be opened.
+            throw new FileNotFoundException("Could not write to file: " + path.toAbsolutePath());
+        }
+        // will throw if non-writeable
+        BufferedWriter fw = Files.newBufferedWriter(path);
+        fw.close();
+        this.original = path;
+        this.real = path.toRealPath();
+        this.text = real.toString();
+    }
+
+    /**
+     * Returns a potentially malicious path where the user may have implemented
+     * their own version of Path. This method should never be called in an
+     * unsafe context and the Path value should never be passed along to other
+     * methods.
+     *
+     * @return path from a potentially malicious user
+     */
+    public Path getPotentiallyMaliciousOriginal() {
+        return original;
+    }
+
+    /**
+     * Returns a string representation of the path.
+     *
+     * @return path as text
+     */
+    public String getText() {
+        return text;
+    }
+
+    /**
+     * Returns a potentially malicious path where the user may have implemented
+     * their own version of Path. This method should never be called in an
+     * unsafe context and the Path value should never be passed along to other
+     * methods.
+     *
+     * @return path from a potentially malicious user
+     */
+    public Path getReal() {
+        if (!inPrivileged) {
+            throw new InternalError("A user path was accessed outside the context it was supplied in");
+        }
+        return real;
+    }
+
+    public void doPriviligedIO(Callable<?> function) throws IOException {
+        try {
+            inPrivileged = true;
+            AccessController.doPrivileged(new PrivilegedExceptionAction<Void>() {
+                @Override
+                public Void run() throws Exception {
+                    function.call();
+                    return null;
+                }
+            }, controlContext);
+        } catch (Throwable t) {
+            // prevent malicious user to propagate exception callback
+            // in the wrong context
+            throw new IOException("Unexpected error during I/O operation");
+        } finally {
+            inPrivileged = false;
+        }
+    }
+}