Fix error occurring when SecurityManager is enabled

It's expected that jgit should work without native git installation.
In such case Security Manager can be configured to deny access to the
files outside of git repository. JGit tries to find cygwin
installation. If Security manager restricts access to some folders
in PATH, it should be considered that those folders are absent
for jgit.
Also JGit tries to detect if symbolic links are supported by OS. If
security manager forbids creation of symlinks, it should be assumed
that symlinks aren't supported.

Bug: 550115
Change-Id: Ic4b243cada604bc1090db6cc1cfd74f0fa324b98
Signed-off-by: Nail Samatov <sanail@yandex.ru>

1 files changed, 94 insertions, 0 deletions

diff --git a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/SeparateClassloaderTestRunner.java b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/SeparateClassloaderTestRunner.java
new file mode 100644
index 0000000000..926a19599e
--- /dev/null
+++ b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/SeparateClassloaderTestRunner.java
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2019 Nail Samatov <sanail@yandex.ru>
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.junit;
+
+import static java.lang.ClassLoader.getSystemClassLoader;
+
+import java.net.URL;
+import java.net.URLClassLoader;
+
+import org.junit.runners.BlockJUnit4ClassRunner;
+import org.junit.runners.model.InitializationError;
+
+/**
+ * This class is used when it's required to load jgit classes in separate
+ * classloader for each test class. It can be needed to isolate static field
+ * initialization between separate tests.
+ */
+public class SeparateClassloaderTestRunner extends BlockJUnit4ClassRunner {
+
+	/**
+	 * Creates a SeparateClassloaderTestRunner to run {@code klass}.
+	 *
+	 * @param klass
+	 *            test class to run.
+	 * @throws InitializationError
+	 *             if the test class is malformed or can't be found.
+	 */
+	public SeparateClassloaderTestRunner(Class<?> klass)
+			throws InitializationError {
+		super(loadNewClass(klass));
+	}
+
+	private static Class<?> loadNewClass(Class<?> klass)
+			throws InitializationError {
+		try {
+			URL[] urls = ((URLClassLoader) getSystemClassLoader()).getURLs();
+			ClassLoader testClassLoader = new URLClassLoader(urls) {
+
+				@Override
+				public Class<?> loadClass(String name)
+						throws ClassNotFoundException {
+					if (name.startsWith("org.eclipse.jgit.")) {
+						return super.findClass(name);
+					}
+
+					return super.loadClass(name);
+				}
+			};
+			return Class.forName(klass.getName(), true, testClassLoader);
+		} catch (ClassNotFoundException e) {
+			throw new InitializationError(e);
+		}
+	}
+}