1 /*
   2  * Copyright (c) 2014, 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 package jdk.vm.ci.services;
  24 
  25 import java.lang.reflect.Method;
  26 import java.util.Map;
  27 
  28 /**
  29  * Provides utilities needed by JVMCI clients.
  30  */
  31 public final class Services {
  32 
  33     // This class must be compilable and executable on JDK 8 since it's used in annotation
  34     // processors while building JDK 9 so use of API added in JDK 9 is made via reflection.
  35 
  36     private Services() {
  37     }
  38 
  39     @SuppressWarnings("unchecked")
  40     private static Map<String, String> initSavedProperties() throws InternalError {
  41         try {
  42             Class<?> vmClass = Class.forName("jdk.internal.misc.VM");
  43             Method m = vmClass.getMethod("getSavedProperties");
  44             return (Map<String, String>) m.invoke(null);
  45         } catch (Exception e) {
  46             throw new InternalError(e);
  47         }
  48     }
  49 
  50     static final Map<String, String> SAVED_PROPERTIES = initSavedProperties();
  51     static final boolean JVMCI_ENABLED = Boolean.parseBoolean(SAVED_PROPERTIES.get("jdk.internal.vm.ci.enabled"));
  52 
  53     /**
  54      * Checks that JVMCI is enabled in the VM and throws an error if it isn't.
  55      */
  56     static void checkJVMCIEnabled() {
  57         if (!JVMCI_ENABLED) {
  58             throw new Error("The EnableJVMCI VM option must be true (i.e., -XX:+EnableJVMCI) to use JVMCI");
  59         }
  60     }
  61 
  62     /**
  63      * Gets an unmodifiable copy of the system properties saved when {@link System} is initialized.
  64      */
  65     public static Map<String, String> getSavedProperties() {
  66         checkJVMCIEnabled();
  67         SecurityManager sm = System.getSecurityManager();
  68         if (sm != null) {
  69             sm.checkPermission(new JVMCIPermission());
  70         }
  71         return SAVED_PROPERTIES;
  72     }
  73 
  74     /**
  75      * Causes the JVMCI subsystem to be initialized if it isn't already initialized.
  76      */
  77     public static void initializeJVMCI() {
  78         checkJVMCIEnabled();
  79         try {
  80             Class.forName("jdk.vm.ci.runtime.JVMCI");
  81         } catch (ClassNotFoundException e) {
  82             throw new InternalError(e);
  83         }
  84     }
  85 }