1 /*
   2  * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /*
  25  * @test
  26  * @requires vm.compMode != "Xcomp"
  27  * @bug 8058897
  28  * @library /test/lib
  29  * @modules java.base/jdk.internal.misc
  30  *          java.management
  31  * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:MallocMaxTestWords=100m Reallocate
  32  */
  33 
  34 import jdk.internal.misc.Unsafe;
  35 import static jdk.test.lib.Asserts.*;
  36 
  37 public class Reallocate {
  38     public static void main(String args[]) throws Exception {
  39         Unsafe unsafe = Unsafe.getUnsafe();
  40 
  41         long address = unsafe.allocateMemory(1);
  42         assertNotEquals(address, 0L);
  43 
  44         // Make sure we reallocate correctly
  45         unsafe.putByte(address, Byte.MAX_VALUE);
  46         address = unsafe.reallocateMemory(address, 2);
  47         assertNotEquals(address, 0L);
  48         assertEquals(unsafe.getByte(address), Byte.MAX_VALUE);
  49 
  50         // Reallocating with a 0 size should return a null pointer
  51         address = unsafe.reallocateMemory(address, 0);
  52         assertEquals(address, 0L);
  53 
  54         // Reallocating with a null pointer should result in a normal allocation
  55         address = unsafe.reallocateMemory(0L, 1);
  56         assertNotEquals(address, 0L);
  57         unsafe.putByte(address, Byte.MAX_VALUE);
  58         assertEquals(unsafe.getByte(address), Byte.MAX_VALUE);
  59 
  60         // Make sure we can throw an OOME when we fail to reallocate due to OOM
  61         try {
  62             unsafe.reallocateMemory(address, 100 * 1024 * 1024 * 8);
  63         } catch (OutOfMemoryError e) {
  64             // Expected
  65             return;
  66         }
  67         throw new RuntimeException("Did not get expected OOM");
  68     }
  69 }