Mercurial > jdk8-mips64-public > nashorn / file revision

 /*

  * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

  * 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.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * 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 jdk.nashorn.internal.runtime;

 import static jdk.nashorn.internal.codegen.CompilerConstants.RUN_SCRIPT;

 import static jdk.nashorn.internal.codegen.CompilerConstants.STRICT_MODE;

 import static jdk.nashorn.internal.lookup.Lookup.MH;

 import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;

 import static jdk.nashorn.internal.runtime.ScriptRuntime.UNDEFINED;

 import java.io.File;

 import java.io.IOException;

 import java.io.PrintWriter;

 import java.lang.invoke.MethodHandle;

 import java.lang.invoke.MethodHandles;

 import java.lang.reflect.Modifier;

 import java.util.concurrent.atomic.AtomicLong;

 import java.net.MalformedURLException;

 import java.net.URL;

 import java.security.AccessControlContext;

 import java.security.AccessController;

 import java.security.CodeSigner;

 import java.security.CodeSource;

 import java.security.Permissions;

 import java.security.PrivilegedAction;

 import java.security.ProtectionDomain;

 import java.util.Map;

 import jdk.internal.org.objectweb.asm.ClassReader;

 import jdk.internal.org.objectweb.asm.util.CheckClassAdapter;

 import jdk.nashorn.api.scripting.ScriptObjectMirror;

 import jdk.nashorn.internal.codegen.Compiler;

 import jdk.nashorn.internal.codegen.ObjectClassGenerator;

 import jdk.nashorn.internal.ir.FunctionNode;

 import jdk.nashorn.internal.ir.debug.ASTWriter;

 import jdk.nashorn.internal.ir.debug.PrintVisitor;

 import jdk.nashorn.internal.objects.Global;

 import jdk.nashorn.internal.parser.Parser;

 import jdk.nashorn.internal.runtime.options.Options;

 /**

  * This class manages the global state of execution. Context is immutable.

  */

 public final class Context {

     // nashorn specific security runtime access permission names

     /**

      * Permission needed to pass arbitrary nashorn command line options when creating Context.

      */

     public static final String NASHORN_SET_CONFIG      = "nashorn.setConfig";

     /**

      * Permission needed to create Nashorn Context instance.

      */

     public static final String NASHORN_CREATE_CONTEXT  = "nashorn.createContext";

     /**

      * Permission needed to create Nashorn Global instance.

      */

     public static final String NASHORN_CREATE_GLOBAL   = "nashorn.createGlobal";

     /**

      * Permission to get current Nashorn Context from thread local storage.

      */

     public static final String NASHORN_GET_CONTEXT     = "nashorn.getContext";

     /**

      * Permission to use Java reflection/jsr292 from script code.

      */

     public static final String NASHORN_JAVA_REFLECTION = "nashorn.JavaReflection";

     // nashorn load psuedo URL prefixes

     private static final String LOAD_CLASSPATH = "classpath:";

     private static final String LOAD_FX = "fx:";

     private static final String LOAD_NASHORN = "nashorn:";

     /* Force DebuggerSupport to be loaded. */

     static {

         DebuggerSupport.FORCELOAD = true;

     }

     /**

      * ContextCodeInstaller that has the privilege of installing classes in the Context.

      * Can only be instantiated from inside the context and is opaque to other classes

      */

     public static class ContextCodeInstaller implements CodeInstaller<ScriptEnvironment> {

         private final Context      context;

         private final ScriptLoader loader;

         private final CodeSource   codeSource;

         private ContextCodeInstaller(final Context context, final ScriptLoader loader, final CodeSource codeSource) {

             this.context    = context;

             this.loader     = loader;

             this.codeSource = codeSource;

         }

         /**

          * Return the context for this installer

          * @return ScriptEnvironment

          */

         @Override

         public ScriptEnvironment getOwner() {

             return context.env;

         }

         @Override

         public Class<?> install(final String className, final byte[] bytecode) {

             return loader.installClass(className, bytecode, codeSource);

         }

         @Override

         public void verify(final byte[] code) {

             context.verify(code);

         }

         @Override

         public long getUniqueScriptId() {

             return context.getUniqueScriptId();

         }

     }

     /** Is Context global debug mode enabled ? */

     public static final boolean DEBUG = Options.getBooleanProperty("nashorn.debug");

     private static final ThreadLocal<ScriptObject> currentGlobal = new ThreadLocal<>();

     /**

      * Get the current global scope

      * @return the current global scope

      */

     public static ScriptObject getGlobal() {

         // This class in a package.access protected package.

         // Trusted code only can call this method.

         return getGlobalTrusted();

     }

     /**

      * Set the current global scope

      * @param global the global scope

      */

     public static void setGlobal(final ScriptObject global) {

         if (global != null && !(global instanceof Global)) {

             throw new IllegalArgumentException("global is not an instance of Global!");

         }

         setGlobalTrusted(global);

     }

     /**

      * Get context of the current global

      * @return current global scope's context.

      */

     public static Context getContext() {

         final SecurityManager sm = System.getSecurityManager();

         if (sm != null) {

             sm.checkPermission(new RuntimePermission(NASHORN_GET_CONTEXT));

         }

         return getContextTrusted();

     }

     /**

      * Get current context's error writer

      *

      * @return error writer of the current context

      */

     public static PrintWriter getCurrentErr() {

         final ScriptObject global = getGlobalTrusted();

         return (global != null)? global.getContext().getErr() : new PrintWriter(System.err);

     }

     /**

      * Output text to this Context's error stream

      * @param str text to write

      */

     public static void err(final String str) {

         err(str, true);

     }

     /**

      * Output text to this Context's error stream, optionally with

      * a newline afterwards

      *

      * @param str  text to write

      * @param crlf write a carriage return/new line after text

      */

     @SuppressWarnings("resource")

     public static void err(final String str, final boolean crlf) {

         final PrintWriter err = Context.getCurrentErr();

         if (err != null) {

             if (crlf) {

                 err.println(str);

             } else {

                 err.print(str);

             }

         }

     }

     /** Current environment. */

     private final ScriptEnvironment env;

     /** is this context in strict mode? Cached from env. as this is used heavily. */

     final boolean _strict;

     /** class loader to resolve classes from script. */

     private final ClassLoader  appLoader;

     /** Class loader to load classes from -classpath option, if set. */

     private final ClassLoader  classPathLoader;

     /** Class loader to load classes compiled from scripts. */

     private final ScriptLoader scriptLoader;

     /** Current error manager. */

     private final ErrorManager errors;

     /** Unique id for script. Used only when --loader-per-compile=false */

     private final AtomicLong uniqueScriptId;

     private static final ClassLoader myLoader = Context.class.getClassLoader();

     private static final StructureLoader sharedLoader;

     /*package-private*/ ClassLoader getSharedLoader() {

         return sharedLoader;

     }

     private static AccessControlContext createNoPermAccCtxt() {

         return new AccessControlContext(new ProtectionDomain[] { new ProtectionDomain(null, new Permissions()) });

     }

     private static AccessControlContext createPermAccCtxt(final String permName) {

         final Permissions perms = new Permissions();

         perms.add(new RuntimePermission(permName));

         return new AccessControlContext(new ProtectionDomain[] { new ProtectionDomain(null, perms) });

     }

     private static final AccessControlContext NO_PERMISSIONS_ACC_CTXT = createNoPermAccCtxt();

     private static final AccessControlContext CREATE_LOADER_ACC_CTXT  = createPermAccCtxt("createClassLoader");

     private static final AccessControlContext CREATE_GLOBAL_ACC_CTXT  = createPermAccCtxt(NASHORN_CREATE_GLOBAL);

     static {

         sharedLoader = AccessController.doPrivileged(new PrivilegedAction<StructureLoader>() {

             @Override

             public StructureLoader run() {

                 return new StructureLoader(myLoader);

             }

         }, CREATE_LOADER_ACC_CTXT);

     }

     /**

      * ThrowErrorManager that throws ParserException upon error conditions.

      */

     public static class ThrowErrorManager extends ErrorManager {

         @Override

         public void error(final String message) {

             throw new ParserException(message);

         }

         @Override

         public void error(final ParserException e) {

             throw e;

         }

     }

     /**

      * Constructor

      *

      * @param options options from command line or Context creator

      * @param errors  error manger

      * @param appLoader application class loader

      */

     public Context(final Options options, final ErrorManager errors, final ClassLoader appLoader) {

         this(options, errors, new PrintWriter(System.out, true), new PrintWriter(System.err, true), appLoader);

     }

     /**

      * Constructor

      *

      * @param options options from command line or Context creator

      * @param errors  error manger

      * @param out     output writer for this Context

      * @param err     error writer for this Context

      * @param appLoader application class loader

      */

     public Context(final Options options, final ErrorManager errors, final PrintWriter out, final PrintWriter err, final ClassLoader appLoader) {

         final SecurityManager sm = System.getSecurityManager();

         if (sm != null) {

             sm.checkPermission(new RuntimePermission(NASHORN_CREATE_CONTEXT));

         }

         this.env       = new ScriptEnvironment(options, out, err);

         this._strict   = env._strict;

         this.appLoader = appLoader;

         if (env._loader_per_compile) {

             this.scriptLoader = null;

             this.uniqueScriptId = null;

         } else {

             this.scriptLoader = createNewLoader();

             this.uniqueScriptId = new AtomicLong();

         }

         this.errors    = errors;

         // if user passed -classpath option, make a class loader with that and set it as

         // thread context class loader so that script can access classes from that path.

         final String classPath = options.getString("classpath");

         if (! env._compile_only && classPath != null && !classPath.isEmpty()) {

             // make sure that caller can create a class loader.

             if (sm != null) {

                 sm.checkPermission(new RuntimePermission("createClassLoader"));

             }

             this.classPathLoader = NashornLoader.createClassLoader(classPath);

         } else {

             this.classPathLoader = null;

         }

         // print version info if asked.

         if (env._version) {

             getErr().println("nashorn " + Version.version());

         }

         if (env._fullversion) {

             getErr().println("nashorn full version " + Version.fullVersion());

         }

     }

     /**

      * Get the error manager for this context

      * @return error manger

      */

     public ErrorManager getErrorManager() {

         return errors;

     }

     /**

      * Get the script environment for this context

      * @return script environment

      */

     public ScriptEnvironment getEnv() {

         return env;

     }

     /**

      * Get the output stream for this context

      * @return output print writer

      */

     public PrintWriter getOut() {

         return env.getOut();

     }

     /**

      * Get the error stream for this context

      * @return error print writer

      */

     public PrintWriter getErr() {

         return env.getErr();

     }

     /**

      * Get the PropertyMap of the current global scope

      * @return the property map of the current global scope

      */

     public static PropertyMap getGlobalMap() {

         return Context.getGlobalTrusted().getMap();

     }

     /**

      * Compile a top level script.

      *

      * @param source the source

      * @param scope  the scope

      *

      * @return top level function for script

      */

     public ScriptFunction compileScript(final Source source, final ScriptObject scope) {

         return compileScript(source, scope, this.errors);

     }

     /**

      * Entry point for {@code eval}

      *

      * @param initialScope The scope of this eval call

      * @param string       Evaluated code as a String

      * @param callThis     "this" to be passed to the evaluated code

      * @param location     location of the eval call

      * @param strict       is this {@code eval} call from a strict mode code?

      *

      * @return the return value of the {@code eval}

      */

     public Object eval(final ScriptObject initialScope, final String string, final Object callThis, final Object location, final boolean strict) {

         final String  file       = (location == UNDEFINED || location == null) ? "<eval>" : location.toString();

         final Source  source     = new Source(file, string);

         final boolean directEval = location != UNDEFINED; // is this direct 'eval' call or indirectly invoked eval?

         final ScriptObject global = Context.getGlobalTrusted();

         ScriptObject scope = initialScope;

         // ECMA section 10.1.1 point 2 says eval code is strict if it begins

         // with "use strict" directive or eval direct call itself is made

         // from from strict mode code. We are passed with caller's strict mode.

         boolean strictFlag = directEval && strict;

         Class<?> clazz = null;

         try {

             clazz = compile(source, new ThrowErrorManager(), strictFlag);

         } catch (final ParserException e) {

             e.throwAsEcmaException(global);

             return null;

         }

         if (!strictFlag) {

             // We need to get strict mode flag from compiled class. This is

             // because eval code may start with "use strict" directive.

             try {

                 strictFlag = clazz.getField(STRICT_MODE.symbolName()).getBoolean(null);

             } catch (final NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {

                 //ignored

                 strictFlag = false;

             }

         }

         // In strict mode, eval does not instantiate variables and functions

         // in the caller's environment. A new environment is created!

         if (strictFlag) {

             // Create a new scope object

             final ScriptObject strictEvalScope = ((GlobalObject)global).newObject();

             // bless it as a "scope"

             strictEvalScope.setIsScope();

             // set given scope to be it's proto so that eval can still

             // access caller environment vars in the new environment.

             strictEvalScope.setProto(scope);

             scope = strictEvalScope;

         }

         ScriptFunction func = getRunScriptFunction(clazz, scope);

         Object evalThis;

         if (directEval) {

             evalThis = (callThis instanceof ScriptObject || strictFlag) ? callThis : global;

         } else {

             evalThis = global;

         }

         return ScriptRuntime.apply(func, evalThis);

     }

     private static Source loadInternal(final String srcStr, final String prefix, final String resourcePath) {

         if (srcStr.startsWith(prefix)) {

             final String resource = resourcePath + srcStr.substring(prefix.length());

             // NOTE: even sandbox scripts should be able to load scripts in nashorn: scheme

             // These scripts are always available and are loaded from nashorn.jar's resources.

             return AccessController.doPrivileged(

                     new PrivilegedAction<Source>() {

                         @Override

                         public Source run() {

                             try {

                                 final URL resURL = Context.class.getResource(resource);

                                 return (resURL != null)? new Source(srcStr, resURL) : null;

                             } catch (final IOException exp) {

                                 return null;

                             }

                         }

                     });

         }

         return null;

     }

     /**

      * Implementation of {@code load} Nashorn extension. Load a script file from a source

      * expression

      *

      * @param scope  the scope

      * @param from   source expression for script

      *

      * @return return value for load call (undefined)

      *

      * @throws IOException if source cannot be found or loaded

      */

     public Object load(final ScriptObject scope, final Object from) throws IOException {

         final Object src = (from instanceof ConsString)?  from.toString() : from;

         Source source = null;

         // load accepts a String (which could be a URL or a file name), a File, a URL

         // or a ScriptObject that has "name" and "source" (string valued) properties.

         if (src instanceof String) {

             final String srcStr = (String)src;

             if (srcStr.startsWith(LOAD_CLASSPATH)) {

                 URL url = getResourceURL(srcStr.substring(LOAD_CLASSPATH.length()));

                 source = (url != null)? new Source(url.toString(), url) : null;

             } else {

                 final File file = new File(srcStr);

                 if (srcStr.indexOf(':') != -1) {

                     if ((source = loadInternal(srcStr, LOAD_NASHORN, "resources/")) == null &&

                         (source = loadInternal(srcStr, LOAD_FX, "resources/fx/")) == null) {

                         URL url;

                         try {

                             //check for malformed url. if malformed, it may still be a valid file

                             url = new URL(srcStr);

                         } catch (final MalformedURLException e) {

                             url = file.toURI().toURL();

                         }

                         source = new Source(url.toString(), url);

                     }

                 } else if (file.isFile()) {

                     source = new Source(srcStr, file);

                 }

             }

         } else if (src instanceof File && ((File)src).isFile()) {

             final File file = (File)src;

             source = new Source(file.getName(), file);

         } else if (src instanceof URL) {

             final URL url = (URL)src;

             source = new Source(url.toString(), url);

         } else if (src instanceof ScriptObject) {

             final ScriptObject sobj = (ScriptObject)src;

             if (sobj.has("script") && sobj.has("name")) {

                 final String script = JSType.toString(sobj.get("script"));

                 final String name   = JSType.toString(sobj.get("name"));

                 source = new Source(name, script);

             }

         } else if (src instanceof Map) {

             final Map<?,?> map = (Map<?,?>)src;

             if (map.containsKey("script") && map.containsKey("name")) {

                 final String script = JSType.toString(map.get("script"));

                 final String name   = JSType.toString(map.get("name"));

                 source = new Source(name, script);

             }

         }

         if (source != null) {

             return evaluateSource(source, scope, scope);

         }

         throw typeError("cant.load.script", ScriptRuntime.safeToString(from));

     }

     /**

      * Implementation of {@code loadWithNewGlobal} Nashorn extension. Load a script file from a source

      * expression, after creating a new global scope.

      *

      * @param from source expression for script

      * @param args (optional) arguments to be passed to the loaded script

      *

      * @return return value for load call (undefined)

      *

      * @throws IOException if source cannot be found or loaded

      */

     public Object loadWithNewGlobal(final Object from, final Object...args) throws IOException {

         final ScriptObject oldGlobal = getGlobalTrusted();

         final ScriptObject newGlobal = AccessController.doPrivileged(new PrivilegedAction<ScriptObject>() {

            @Override

            public ScriptObject run() {

                try {

                    return newGlobal();

                } catch (final RuntimeException e) {

                    if (Context.DEBUG) {

                        e.printStackTrace();

                    }

                    throw e;

                }

            }

         }, CREATE_GLOBAL_ACC_CTXT);

         // initialize newly created Global instance

         initGlobal(newGlobal);

         setGlobalTrusted(newGlobal);

         final Object[] wrapped = args == null? ScriptRuntime.EMPTY_ARRAY :  ScriptObjectMirror.wrapArray(args, oldGlobal);

         newGlobal.put("arguments", ((GlobalObject)newGlobal).wrapAsObject(wrapped), env._strict);

         try {

             // wrap objects from newGlobal's world as mirrors - but if result

             // is from oldGlobal's world, unwrap it!

             return ScriptObjectMirror.unwrap(ScriptObjectMirror.wrap(load(newGlobal, from), newGlobal), oldGlobal);

         } finally {

             setGlobalTrusted(oldGlobal);

         }

     }

     /**

      * Load or get a structure class. Structure class names are based on the number of parameter fields

      * and {@link AccessorProperty} fields in them. Structure classes are used to represent ScriptObjects

      *

      * @see ObjectClassGenerator

      * @see AccessorProperty

      * @see ScriptObject

      *

      * @param fullName  full name of class, e.g. jdk.nashorn.internal.objects.JO2P1 contains 2 fields and 1 parameter.

      *

      * @return the {@code Class<?>} for this structure

      *

      * @throws ClassNotFoundException if structure class cannot be resolved

      */

     public static Class<?> forStructureClass(final String fullName) throws ClassNotFoundException {

         if (System.getSecurityManager() != null && !StructureLoader.isStructureClass(fullName)) {

             throw new ClassNotFoundException(fullName);

         }

         return Class.forName(fullName, true, sharedLoader);

     }

     /**

      * Checks that the given Class can be accessed from no permissions context.

      *

      * @param clazz Class object

      * @throw SecurityException if not accessible

      */

     public static void checkPackageAccess(final Class clazz) {

         final SecurityManager sm = System.getSecurityManager();

         if (sm != null) {

             Class bottomClazz = clazz;

             while(bottomClazz.isArray()) {

                 bottomClazz = bottomClazz.getComponentType();

             }

             checkPackageAccess(sm, bottomClazz.getName());

         }

     }

     /**

      * Checks that the given package can be accessed from no permissions context.

      *

      * @param sm current security manager instance

      * @param fullName fully qualified package name

      * @throw SecurityException if not accessible

      */

     private static void checkPackageAccess(final SecurityManager sm, final String fullName) {

         sm.getClass(); // null check

         final int index = fullName.lastIndexOf('.');

         if (index != -1) {

             final String pkgName = fullName.substring(0, index);

             AccessController.doPrivileged(new PrivilegedAction<Void>() {

                 @Override

                 public Void run() {

                     sm.checkPackageAccess(pkgName);

                     return null;

                 }

             }, NO_PERMISSIONS_ACC_CTXT);

         }

     }

     /**

      * Checks that the given Class can be accessed from no permissions context.

      *

      * @param clazz Class object

      * @return true if package is accessible, false otherwise

      */

     private static boolean isAccessiblePackage(final Class clazz) {

         try {

             checkPackageAccess(clazz);

             return true;

         } catch (final SecurityException se) {

             return false;

         }

     }

     /**

      * Checks that the given Class is public and it can be accessed from no permissions context.

      *

      * @param clazz Class object to check

      * @return true if Class is accessible, false otherwise

      */

     public static boolean isAccessibleClass(final Class<?> clazz) {

         return Modifier.isPublic(clazz.getModifiers()) && Context.isAccessiblePackage(clazz);

     }

     /**

      * Lookup a Java class. This is used for JSR-223 stuff linking in from

      * {@code jdk.nashorn.internal.objects.NativeJava} and {@code jdk.nashorn.internal.runtime.NativeJavaPackage}

      *

      * @param fullName full name of class to load

      *

      * @return the {@code Class<?>} for the name

      *

      * @throws ClassNotFoundException if class cannot be resolved

      */

     public Class<?> findClass(final String fullName) throws ClassNotFoundException {

         if (fullName.indexOf('[') != -1 || fullName.indexOf('/') != -1) {

             // don't allow array class names or internal names.

             throw new ClassNotFoundException(fullName);

         }

         // check package access as soon as possible!

         final SecurityManager sm = System.getSecurityManager();

         if (sm != null) {

             checkPackageAccess(sm, fullName);

         }

         // try the script -classpath loader, if that is set

         if (classPathLoader != null) {

             try {

                 return Class.forName(fullName, true, classPathLoader);

             } catch (final ClassNotFoundException ignored) {

                 // ignore, continue search

             }

         }

         // Try finding using the "app" loader.

         return Class.forName(fullName, true, appLoader);

     }

     /**

      * Hook to print stack trace for a {@link Throwable} that occurred during

      * execution

      *

      * @param t throwable for which to dump stack

      */

     public static void printStackTrace(final Throwable t) {

         if (Context.DEBUG) {

             t.printStackTrace(Context.getCurrentErr());

         }

     }

     /**

      * Verify generated bytecode before emission. This is called back from the

      * {@link ObjectClassGenerator} or the {@link Compiler}. If the "--verify-code" parameter

      * hasn't been given, this is a nop

      *

      * Note that verification may load classes -- we don't want to do that unless

      * user specified verify option. We check it here even though caller

      * may have already checked that flag

      *

      * @param bytecode bytecode to verify

      */

     public void verify(final byte[] bytecode) {

         if (env._verify_code) {

             // No verification when security manager is around as verifier

             // may load further classes - which should be avoided.

             if (System.getSecurityManager() == null) {

                 CheckClassAdapter.verify(new ClassReader(bytecode), sharedLoader, false, new PrintWriter(System.err, true));

             }

         }

     }

     /**

      * Create and initialize a new global scope object.

      *

      * @return the initialized global scope object.

      */

     public ScriptObject createGlobal() {

         return initGlobal(newGlobal());

     }

     /**

      * Create a new uninitialized global scope object

      * @return the global script object

      */

     public ScriptObject newGlobal() {

         return new Global(this);

     }

     /**

      * Initialize given global scope object.

      *

      * @param global the global

      * @return the initialized global scope object.

      */

     public ScriptObject initGlobal(final ScriptObject global) {

         if (! (global instanceof GlobalObject)) {

             throw new IllegalArgumentException("not a global object!");

         }

         // Need only minimal global object, if we are just compiling.

         if (!env._compile_only) {

             final ScriptObject oldGlobal = Context.getGlobalTrusted();

             try {

                 Context.setGlobalTrusted(global);

                 // initialize global scope with builtin global objects

                 ((GlobalObject)global).initBuiltinObjects();

             } finally {

                 Context.setGlobalTrusted(oldGlobal);

             }

         }

         return global;

     }

     /**

      * Trusted variants - package-private

      */

     /**

      * Return the current global scope

      * @return current global scope

      */

     static ScriptObject getGlobalTrusted() {

         return currentGlobal.get();

     }

     /**

      * Set the current global scope

      */

     static void setGlobalTrusted(ScriptObject global) {

          currentGlobal.set(global);

     }

     /**

      * Return the current global's context

      * @return current global's context

      */

     static Context getContextTrusted() {

         return Context.getGlobalTrusted().getContext();

     }

     /**

      * Try to infer Context instance from the Class. If we cannot,

      * then get it from the thread local variable.

      *

      * @param clazz the class

      * @return context

      */

     static Context fromClass(final Class<?> clazz) {

         final ClassLoader loader = clazz.getClassLoader();

         if (loader instanceof ScriptLoader) {

             return ((ScriptLoader)loader).getContext();

         }

         return Context.getContextTrusted();

     }

     private URL getResourceURL(final String resName) throws IOException {

         // try the classPathLoader if we have and then

         // try the appLoader if non-null.

         if (classPathLoader != null) {

             return classPathLoader.getResource(resName);

         } else if (appLoader != null) {

             return appLoader.getResource(resName);

         }

         return null;

     }

     private Object evaluateSource(final Source source, final ScriptObject scope, final ScriptObject thiz) {

         ScriptFunction script = null;

         try {

             script = compileScript(source, scope, new Context.ThrowErrorManager());

         } catch (final ParserException e) {

             e.throwAsEcmaException();

         }

         return ScriptRuntime.apply(script, thiz);

     }

     private static ScriptFunction getRunScriptFunction(final Class<?> script, final ScriptObject scope) {

         if (script == null) {

             return null;

         }

         // Get run method - the entry point to the script

         final MethodHandle runMethodHandle =

                 MH.findStatic(

                     MethodHandles.lookup(),

                     script,

                     RUN_SCRIPT.symbolName(),

                     MH.type(

                         Object.class,

                         ScriptFunction.class,

                         Object.class));

         boolean strict;

         try {

             strict = script.getField(STRICT_MODE.symbolName()).getBoolean(null);

         } catch (final NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {

             strict = false;

         }

         // Package as a JavaScript function and pass function back to shell.

         return ((GlobalObject)Context.getGlobalTrusted()).newScriptFunction(RUN_SCRIPT.symbolName(), runMethodHandle, scope, strict);

     }

     private ScriptFunction compileScript(final Source source, final ScriptObject scope, final ErrorManager errMan) {

         return getRunScriptFunction(compile(source, errMan, this._strict), scope);

     }

     private synchronized Class<?> compile(final Source source, final ErrorManager errMan, final boolean strict) {

         // start with no errors, no warnings.

         errMan.reset();

         GlobalObject global = null;

         Class<?> script;

         if (env._class_cache_size > 0) {

             global = (GlobalObject)Context.getGlobalTrusted();

             script = global.findCachedClass(source);

             if (script != null) {

                 Compiler.LOG.fine("Code cache hit for ", source, " avoiding recompile.");

                 return script;

             }

         }

         final FunctionNode functionNode = new Parser(env, source, errMan, strict).parse();

         if (errors.hasErrors()) {

             return null;

         }

         if (env._print_ast) {

             getErr().println(new ASTWriter(functionNode));

         }

         if (env._print_parse) {

             getErr().println(new PrintVisitor(functionNode));

         }

         if (env._parse_only) {

             return null;

         }

         final URL          url    = source.getURL();

         final ScriptLoader loader = env._loader_per_compile ? createNewLoader() : scriptLoader;

         final CodeSource   cs     = url == null ? null : new CodeSource(url, (CodeSigner[])null);

         final CodeInstaller<ScriptEnvironment> installer = new ContextCodeInstaller(this, loader, cs);

         final Compiler compiler = new Compiler(installer, strict);

         final FunctionNode newFunctionNode = compiler.compile(functionNode);

         script = compiler.install(newFunctionNode);

         if (global != null) {

             global.cacheClass(source, script);

         }

         return script;

     }

     private ScriptLoader createNewLoader() {

         return AccessController.doPrivileged(

              new PrivilegedAction<ScriptLoader>() {

                 @Override

                 public ScriptLoader run() {

                     return new ScriptLoader(appLoader, Context.this);

                 }

              }, CREATE_LOADER_ACC_CTXT);

     }

     private long getUniqueScriptId() {

         return uniqueScriptId.getAndIncrement();

     }

 }