test/hotspot/jtreg/runtime/exceptionMsgs/IllegalAccessError/IAE_Loader2.java
changeset 50816 a73848f8d0ad
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/runtime/exceptionMsgs/IllegalAccessError/IAE_Loader2.java	Wed Jun 27 09:52:23 2018 +0200
@@ -0,0 +1,166 @@
+/*
+ * Copyright (c) 2018 by SAP AG, Walldorf, Germany.
+ * 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.
+ *
+ * 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 test;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.security.SecureClassLoader;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.stream.Collectors;
+
+/**
+ * This is a class loader which can load the same classes as another class loader.
+ * <p>
+ * This is mainly useful for tests when you want to load a class, but do it with a class
+ * loader you can dispose. The clone loader just asks the loader to be cloned to get
+ * the bytecodes, but defines the class itself.
+ * <p>
+ * Additionally you can specify a set of classes the loader should not be able to load.
+ */
+public class IAE_Loader2 extends SecureClassLoader {
+
+    /**
+     * The class loaded to clone.
+     */
+    private final ClassLoader toClone;
+
+    /**
+     * The strings we cannot load.
+     */
+    private final HashSet<String> notLoadable;
+
+    /**
+     * The strings we just delegate.
+     */
+    private final HashSet<String> simpleDelegate;
+
+    /**
+     * Creates a class loader which can load the same classes as the loader which
+     * loaded the <code>IAE_Loader2</code> class itself.
+     * <p>
+     * Only the classes which are loadable by the 'parent' loader are delegated to that
+     * loader (to make it possible mix classes).
+     *
+     * @param name the name of the class loader.
+     * @param parent the parent loader which is first asked to load a class.
+     * @param toClone the class loader to mimic. The clone class loader will be able to
+     *                load the same classes as the 'toClone' loader.
+     * @param notLoadable The classes we should not be able to load via this loader.
+     * @param simpleDelegate The names of the classes for which we simply delegate.
+     */
+    public IAE_Loader2(String name, ClassLoader parent, ClassLoader toClone,
+                       String[] notLoadable, String[] simpleDelegate) {
+        super(name, parent);
+
+        this.toClone = toClone;
+        this.notLoadable    = Arrays.stream(notLoadable).collect(Collectors.toCollection(HashSet<String>::new));
+        this.simpleDelegate = Arrays.stream(simpleDelegate).collect(Collectors.toCollection(HashSet<String>::new));
+    }
+
+    /**
+     * @see java.lang.ClassLoader#findClass(java.lang.String)
+     */
+    @Override
+    protected Class<?> findClass(String name) throws ClassNotFoundException {
+        if (notLoadable.contains(name)) {
+            throw new ClassNotFoundException("The clone class loader explicitely " +
+                    "didn't found the class");
+        }
+
+        if (simpleDelegate.contains(name)) {
+            return toClone.loadClass(name);
+        }
+
+        // We just ask the wrapper class loader to find the resource for us
+        URL res = toClone.getResource(name.replace('.', '/') + ".class");
+
+        if (res == null) {
+            throw new ClassNotFoundException(name);
+        }
+
+        try {
+            InputStream is = res.openStream();
+            byte[] code = readStreamIntoBuffer(is, 8192);
+            is.close();
+            return defineClass(name, code, 0, code.length);
+        } catch (IOException e) {
+            throw new ClassNotFoundException(name, e);
+        }
+    }
+
+    /**
+     * Reads all data of a stream into a byte array. The method allocates as
+     * much memory as necessary to put the whole data into that byte
+     * array. The data is read in chunks of <code>chunkSize</code>
+     * chunks.<br><br>
+     * <b>Implementation Note: </b> The data is read in chunks of
+     * <code>chunkSize</code> bytes. The data is copied to the result
+     * array. The memory consumption at the end of the reading is
+     * <code>2 x [size of resulting array] + chunkSize</code>.
+     *
+     * @param is the stream to read the data from
+     * @param chunkSize the size of the chunks the data should be read in
+     * @return the <b>whole</b> data of the stream read into an byte array
+     * @throws IllegalArgumentException if chunkSize <= 0
+     * @throws NullPointerException if is == null
+     * @throws IOException thrown if the provided stream encounters IO problems
+     */
+    public static byte[] readStreamIntoBuffer(InputStream is, int chunkSize)
+            throws IOException {
+
+        // Check preconditions.
+        if (chunkSize <= 0) {
+            throw new IllegalArgumentException("chunkSize <= 0");
+        }
+        else if (is == null) {
+            throw new NullPointerException("is is null");
+        }
+
+        // Temporary buffer for read operations and result buffer.
+        byte[] tempBuffer = new byte[chunkSize];
+        byte[] buffer     = new byte[0];
+
+        int bytesRead = 0;  // bytes actual read
+        int oldSize   = 0;  // size of the resulting buffer
+
+        while ((bytesRead = is.read(tempBuffer)) > 0) {
+
+            // Temporary reference to the buffer for the copy operation.
+            byte[] oldBuffer = buffer;
+
+            // Create a new buffer with the size needed and copy data.
+            buffer = new byte[oldSize + bytesRead];
+            System.arraycopy(oldBuffer,  0, buffer, 0,       oldBuffer.length);
+
+            // Copy the new data.
+            System.arraycopy(tempBuffer, 0, buffer, oldSize, bytesRead);
+            oldSize += bytesRead;
+        }
+
+        return buffer;
+    }
+}