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.InvocationTargetException;
  26 import java.lang.reflect.Method;
  27 import java.util.Formatter;
  28 import java.util.Iterator;
  29 import java.util.Map;
  30 import java.util.ServiceConfigurationError;
  31 import java.util.ServiceLoader;
  32 import java.util.Set;
  33 
  34 /**
  35  * Provides utilities needed by JVMCI clients.
  36  *
  37  * This class must be compilable on JDK 8 and so use of API added in JDK 9 is made via reflection.
  38  */
  39 public final class Services {
  40 
  41     private Services() {
  42     }
  43 
  44     /**
  45      * Gets an unmodifiable copy of the system properties saved when {@link System} is initialized.
  46      */
  47     @SuppressWarnings("unchecked")
  48     public static Map<String, String> getSavedProperties() {
  49         SecurityManager sm = System.getSecurityManager();
  50         if (sm != null) {
  51             sm.checkPermission(new JVMCIPermission());
  52         }
  53         try {
  54             Class<?> vmClass = Class.forName("jdk.internal.misc.VM");
  55             Method m = vmClass.getMethod("getSavedProperties");
  56             return (Map<String, String>) m.invoke(null);
  57         } catch (Exception e) {
  58             throw new InternalError(e);
  59         }
  60     }
  61 
  62     /**
  63      * Causes the JVMCI subsystem to be initialized if it isn't already initialized.
  64      */
  65     public static void initializeJVMCI() {
  66         try {
  67             Class.forName("jdk.vm.ci.runtime.JVMCI");
  68         } catch (ClassNotFoundException e) {
  69             throw new InternalError(e);
  70         }
  71     }
  72 
  73     // EVERYTHING BELOW HERE TO BE REMOVED AFTER NECESSARY GRAAL UPDATE
  74 
  75     private static int getJavaSpecificationVersion() {
  76         String value = System.getProperty("java.specification.version");
  77         if (value.startsWith("1.")) {
  78             value = value.substring(2);
  79         }
  80         return Integer.parseInt(value);
  81     }
  82 
  83     /**
  84      * The integer value corresponding to the value of the {@code java.specification.version} system
  85      * property after any leading {@code "1."} has been stripped.
  86      */
  87     public static final int JAVA_SPECIFICATION_VERSION = getJavaSpecificationVersion();
  88 
  89     // Use reflection so that this compiles on Java 8
  90     private static final Method getModule;
  91     private static final Method getPackages;
  92     private static final Method addUses;
  93     private static final Method isExported;
  94     private static final Method addExports;
  95 
  96     static {
  97         if (JAVA_SPECIFICATION_VERSION >= 9) {
  98             try {
  99                 getModule = Class.class.getMethod("getModule");
 100                 Class<?> moduleClass = getModule.getReturnType();
 101                 getPackages = moduleClass.getMethod("getPackages");
 102                 addUses = moduleClass.getMethod("addUses", Class.class);
 103                 isExported = moduleClass.getMethod("isExported", String.class, moduleClass);
 104                 addExports = moduleClass.getMethod("addExports", String.class, moduleClass);
 105             } catch (NoSuchMethodException | SecurityException e) {
 106                 throw new InternalError(e);
 107             }
 108         } else {
 109             getModule = null;
 110             getPackages = null;
 111             addUses = null;
 112             isExported = null;
 113             addExports = null;
 114         }
 115     }
 116 
 117     @SuppressWarnings("unchecked")
 118     static <T> T invoke(Method method, Object receiver, Object... args) {
 119         try {
 120             return (T) method.invoke(receiver, args);
 121         } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
 122             throw new InternalError(e);
 123         }
 124     }
 125 
 126     /**
 127      * Performs any required security checks and dynamic reconfiguration to allow the module of a
 128      * given class to access the classes in the JVMCI module.
 129      *
 130      * Note: This API uses {@link Class} instead of {@code Module} to provide backwards
 131      * compatibility for JVMCI clients compiled against a JDK release earlier than 9.
 132      *
 133      * @param requestor a class requesting access to the JVMCI module for its module
 134      * @throws SecurityException if a security manager is present and it denies
 135      *             {@link JVMCIPermission}
 136      */
 137     public static void exportJVMCITo(Class<?> requestor) {
 138         SecurityManager sm = System.getSecurityManager();
 139         if (sm != null) {
 140             sm.checkPermission(new JVMCIPermission());
 141         }
 142         if (JAVA_SPECIFICATION_VERSION >= 9) {
 143             Object jvmci = invoke(getModule, Services.class);
 144             Object requestorModule = invoke(getModule, requestor);
 145             if (jvmci != requestorModule) {
 146                 Set<String> packages = invoke(getPackages, jvmci);
 147                 for (String pkg : packages) {
 148                     // Export all JVMCI packages dynamically instead
 149                     // of requiring a long list of --add-exports
 150                     // options on the JVM command line.
 151                     boolean exported = invoke(isExported, jvmci, pkg, requestorModule);
 152                     if (!exported) {
 153                         invoke(addExports, jvmci, pkg, requestorModule);
 154                     }
 155                 }
 156             }
 157         }
 158     }
 159 
 160     /**
 161      * Gets an {@link Iterable} of the JVMCI providers available for a given service.
 162      *
 163      * @throws SecurityException if a security manager is present and it denies
 164      *             {@link JVMCIPermission}
 165      */
 166     public static <S> Iterable<S> load(Class<S> service) {
 167         SecurityManager sm = System.getSecurityManager();
 168         if (sm != null) {
 169             sm.checkPermission(new JVMCIPermission());
 170         }
 171         if (JAVA_SPECIFICATION_VERSION >= 9) {
 172             Object jvmci = invoke(getModule, Services.class);
 173             invoke(addUses, jvmci, service);
 174         }
 175 
 176         // Restrict JVMCI clients to be on the class path or module path
 177         return ServiceLoader.load(service, ClassLoader.getSystemClassLoader());
 178     }
 179 
 180     /**
 181      * Gets the JVMCI provider for a given service for which at most one provider must be available.
 182      *
 183      * @param service the service whose provider is being requested
 184      * @param required specifies if an {@link InternalError} should be thrown if no provider of
 185      *            {@code service} is available
 186      * @throws SecurityException if a security manager is present and it denies
 187      *             {@link JVMCIPermission}
 188      */
 189     public static <S> S loadSingle(Class<S> service, boolean required) {
 190         SecurityManager sm = System.getSecurityManager();
 191         if (sm != null) {
 192             sm.checkPermission(new JVMCIPermission());
 193         }
 194         if (JAVA_SPECIFICATION_VERSION >= 9) {
 195             Object jvmci = invoke(getModule, Services.class);
 196             invoke(addUses, jvmci, service);
 197         }
 198         // Restrict JVMCI clients to be on the class path or module path
 199         Iterable<S> providers = ServiceLoader.load(service, ClassLoader.getSystemClassLoader());
 200         S singleProvider = null;
 201         try {
 202             for (Iterator<S> it = providers.iterator(); it.hasNext();) {
 203                 singleProvider = it.next();
 204                 if (it.hasNext()) {
 205                     throw new InternalError(String.format("Multiple %s providers found", service.getName()));
 206                 }
 207             }
 208         } catch (ServiceConfigurationError e) {
 209             // If the service is required we will bail out below.
 210         }
 211         if (singleProvider == null && required) {
 212             String javaHome = System.getProperty("java.home");
 213             String vmName = System.getProperty("java.vm.name");
 214             Formatter errorMessage = new Formatter();
 215             errorMessage.format("The VM does not expose required service %s.%n", service.getName());
 216             errorMessage.format("Currently used Java home directory is %s.%n", javaHome);
 217             errorMessage.format("Currently used VM configuration is: %s", vmName);
 218             throw new UnsupportedOperationException(errorMessage.toString());
 219         }
 220         return singleProvider;
 221     }
 222 
 223 }
--- EOF ---