1 /*
   2  * Copyright (c) 2014, 2017, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.lang;
  27 
  28 import java.io.IOException;
  29 import java.io.InputStream;
  30 import java.lang.annotation.Annotation;
  31 import java.lang.module.Configuration;
  32 import java.lang.module.ModuleReference;
  33 import java.lang.module.ModuleDescriptor;
  34 import java.lang.module.ModuleDescriptor.Exports;
  35 import java.lang.module.ModuleDescriptor.Opens;
  36 import java.lang.module.ModuleDescriptor.Version;
  37 import java.lang.module.ResolvedModule;
  38 import java.lang.reflect.AnnotatedElement;
  39 import java.net.URI;
  40 import java.net.URL;
  41 import java.security.AccessController;
  42 import java.security.PrivilegedAction;
  43 import java.util.Collections;
  44 import java.util.HashMap;
  45 import java.util.HashSet;
  46 import java.util.Iterator;
  47 import java.util.List;
  48 import java.util.Map;
  49 import java.util.Objects;
  50 import java.util.Optional;
  51 import java.util.Set;
  52 import java.util.concurrent.ConcurrentHashMap;
  53 import java.util.function.Function;
  54 import java.util.stream.Collectors;
  55 import java.util.stream.Stream;
  56 
  57 import jdk.internal.loader.BuiltinClassLoader;
  58 import jdk.internal.loader.BootLoader;
  59 import jdk.internal.loader.ClassLoaders;
  60 import jdk.internal.misc.JavaLangAccess;
  61 import jdk.internal.misc.SharedSecrets;
  62 import jdk.internal.module.IllegalAccessLogger;
  63 import jdk.internal.module.ModuleLoaderMap;
  64 import jdk.internal.module.ServicesCatalog;
  65 import jdk.internal.module.Resources;
  66 import jdk.internal.org.objectweb.asm.AnnotationVisitor;
  67 import jdk.internal.org.objectweb.asm.Attribute;
  68 import jdk.internal.org.objectweb.asm.ClassReader;
  69 import jdk.internal.org.objectweb.asm.ClassVisitor;
  70 import jdk.internal.org.objectweb.asm.ClassWriter;
  71 import jdk.internal.org.objectweb.asm.Opcodes;
  72 import jdk.internal.reflect.CallerSensitive;
  73 import jdk.internal.reflect.Reflection;
  74 import sun.security.util.SecurityConstants;
  75 
  76 /**
  77  * Represents a run-time module, either {@link #isNamed() named} or unnamed.
  78  *
  79  * <p> Named modules have a {@link #getName() name} and are constructed by the
  80  * Java Virtual Machine when a graph of modules is defined to the Java virtual
  81  * machine to create a {@linkplain ModuleLayer module layer}. </p>
  82  *
  83  * <p> An unnamed module does not have a name. There is an unnamed module for
  84  * each {@link ClassLoader ClassLoader}, obtained by invoking its {@link
  85  * ClassLoader#getUnnamedModule() getUnnamedModule} method. All types that are
  86  * not in a named module are members of their defining class loader's unnamed
  87  * module. </p>
  88  *
  89  * <p> The package names that are parameters or returned by methods defined in
  90  * this class are the fully-qualified names of the packages as defined in
  91  * section 6.5.3 of <cite>The Java&trade; Language Specification</cite>, for
  92  * example, {@code "java.lang"}. </p>
  93  *
  94  * <p> Unless otherwise specified, passing a {@code null} argument to a method
  95  * in this class causes a {@link NullPointerException NullPointerException} to
  96  * be thrown. </p>
  97  *
  98  * @since 9
  99  * @spec JPMS
 100  * @see Class#getModule()
 101  */
 102 
 103 public final class Module implements AnnotatedElement {
 104 
 105     // the layer that contains this module, can be null
 106     private final ModuleLayer layer;
 107 
 108     // module name and loader, these fields are read by VM
 109     private final String name;
 110     private final ClassLoader loader;
 111 
 112     // the module descriptor
 113     private final ModuleDescriptor descriptor;
 114 
 115 
 116     /**
 117      * Creates a new named Module. The resulting Module will be defined to the
 118      * VM but will not read any other modules, will not have any exports setup
 119      * and will not be registered in the service catalog.
 120      */
 121     Module(ModuleLayer layer,
 122            ClassLoader loader,
 123            ModuleDescriptor descriptor,
 124            URI uri)
 125     {
 126         this.layer = layer;
 127         this.name = descriptor.name();
 128         this.loader = loader;
 129         this.descriptor = descriptor;
 130 
 131         // define module to VM
 132 
 133         boolean isOpen = descriptor.isOpen() || descriptor.isAutomatic();
 134         Version version = descriptor.version().orElse(null);
 135         String vs = Objects.toString(version, null);
 136         String loc = Objects.toString(uri, null);
 137         String[] packages = descriptor.packages().toArray(new String[0]);
 138         defineModule0(this, isOpen, vs, loc, packages);
 139     }
 140 
 141 
 142     /**
 143      * Create the unnamed Module for the given ClassLoader.
 144      *
 145      * @see ClassLoader#getUnnamedModule
 146      */
 147     Module(ClassLoader loader) {
 148         this.layer = null;
 149         this.name = null;
 150         this.loader = loader;
 151         this.descriptor = null;
 152     }
 153 
 154 
 155     /**
 156      * Creates a named module but without defining the module to the VM.
 157      *
 158      * @apiNote This constructor is for VM white-box testing.
 159      */
 160     Module(ClassLoader loader, ModuleDescriptor descriptor) {
 161         this.layer = null;
 162         this.name = descriptor.name();
 163         this.loader = loader;
 164         this.descriptor = descriptor;
 165     }
 166 
 167 
 168     /**
 169      * Returns {@code true} if this module is a named module.
 170      *
 171      * @return {@code true} if this is a named module
 172      *
 173      * @see ClassLoader#getUnnamedModule()
 174      */
 175     public boolean isNamed() {
 176         return name != null;
 177     }
 178 
 179     /**
 180      * Returns the module name or {@code null} if this module is an unnamed
 181      * module.
 182      *
 183      * @return The module name
 184      */
 185     public String getName() {
 186         return name;
 187     }
 188 
 189     /**
 190      * Returns the {@code ClassLoader} for this module.
 191      *
 192      * <p> If there is a security manager then its {@code checkPermission}
 193      * method if first called with a {@code RuntimePermission("getClassLoader")}
 194      * permission to check that the caller is allowed to get access to the
 195      * class loader. </p>
 196      *
 197      * @return The class loader for this module
 198      *
 199      * @throws SecurityException
 200      *         If denied by the security manager
 201      */
 202     public ClassLoader getClassLoader() {
 203         SecurityManager sm = System.getSecurityManager();
 204         if (sm != null) {
 205             sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
 206         }
 207         return loader;
 208     }
 209 
 210     /**
 211      * Returns the module descriptor for this module or {@code null} if this
 212      * module is an unnamed module.
 213      *
 214      * @return The module descriptor for this module
 215      */
 216     public ModuleDescriptor getDescriptor() {
 217         return descriptor;
 218     }
 219 
 220     /**
 221      * Returns the module layer that contains this module or {@code null} if
 222      * this module is not in a module layer.
 223      *
 224      * A module layer contains named modules and therefore this method always
 225      * returns {@code null} when invoked on an unnamed module.
 226      *
 227      * <p> <a href="reflect/Proxy.html#dynamicmodule">Dynamic modules</a> are
 228      * named modules that are generated at runtime. A dynamic module may or may
 229      * not be in a module layer. </p>
 230      *
 231      * @return The module layer that contains this module
 232      *
 233      * @see java.lang.reflect.Proxy
 234      */
 235     public ModuleLayer getLayer() {
 236         if (isNamed()) {
 237             ModuleLayer layer = this.layer;
 238             if (layer != null)
 239                 return layer;
 240 
 241             // special-case java.base as it is created before the boot layer
 242             if (loader == null && name.equals("java.base")) {
 243                 return ModuleLayer.boot();
 244             }
 245         }
 246         return null;
 247     }
 248 
 249     // --
 250 
 251     // special Module to mean "all unnamed modules"
 252     private static final Module ALL_UNNAMED_MODULE = new Module(null);
 253     private static final Set<Module> ALL_UNNAMED_MODULE_SET = Set.of(ALL_UNNAMED_MODULE);
 254 
 255     // special Module to mean "everyone"
 256     private static final Module EVERYONE_MODULE = new Module(null);
 257     private static final Set<Module> EVERYONE_SET = Set.of(EVERYONE_MODULE);
 258 
 259     /**
 260      * The holder of data structures to support readability, exports, and
 261      * service use added at runtime with the reflective APIs.
 262      */
 263     private static class ReflectionData {
 264         /**
 265          * A module (1st key) reads another module (2nd key)
 266          */
 267         static final WeakPairMap<Module, Module, Boolean> reads =
 268             new WeakPairMap<>();
 269 
 270         /**
 271          * A module (1st key) exports or opens a package to another module
 272          * (2nd key). The map value is a map of package name to a boolean
 273          * that indicates if the package is opened.
 274          */
 275         static final WeakPairMap<Module, Module, Map<String, Boolean>> exports =
 276             new WeakPairMap<>();
 277 
 278         /**
 279          * A module (1st key) uses a service (2nd key)
 280          */
 281         static final WeakPairMap<Module, Class<?>, Boolean> uses =
 282             new WeakPairMap<>();
 283     }
 284 
 285 
 286     // -- readability --
 287 
 288     // the modules that this module reads
 289     private volatile Set<Module> reads;
 290 
 291     /**
 292      * Indicates if this module reads the given module. This method returns
 293      * {@code true} if invoked to test if this module reads itself. It also
 294      * returns {@code true} if invoked on an unnamed module (as unnamed
 295      * modules read all modules).
 296      *
 297      * @param  other
 298      *         The other module
 299      *
 300      * @return {@code true} if this module reads {@code other}
 301      *
 302      * @see #addReads(Module)
 303      */
 304     public boolean canRead(Module other) {
 305         Objects.requireNonNull(other);
 306 
 307         // an unnamed module reads all modules
 308         if (!this.isNamed())
 309             return true;
 310 
 311         // all modules read themselves
 312         if (other == this)
 313             return true;
 314 
 315         // check if this module reads other
 316         if (other.isNamed()) {
 317             Set<Module> reads = this.reads; // volatile read
 318             if (reads != null && reads.contains(other))
 319                 return true;
 320         }
 321 
 322         // check if this module reads the other module reflectively
 323         if (ReflectionData.reads.containsKeyPair(this, other))
 324             return true;
 325 
 326         // if other is an unnamed module then check if this module reads
 327         // all unnamed modules
 328         if (!other.isNamed()
 329             && ReflectionData.reads.containsKeyPair(this, ALL_UNNAMED_MODULE))
 330             return true;
 331 
 332         return false;
 333     }
 334 
 335     /**
 336      * If the caller's module is this module then update this module to read
 337      * the given module.
 338      *
 339      * This method is a no-op if {@code other} is this module (all modules read
 340      * themselves), this module is an unnamed module (as unnamed modules read
 341      * all modules), or this module already reads {@code other}.
 342      *
 343      * @implNote <em>Read edges</em> added by this method are <em>weak</em> and
 344      * do not prevent {@code other} from being GC'ed when this module is
 345      * strongly reachable.
 346      *
 347      * @param  other
 348      *         The other module
 349      *
 350      * @return this module
 351      *
 352      * @throws IllegalCallerException
 353      *         If this is a named module and the caller's module is not this
 354      *         module
 355      *
 356      * @see #canRead
 357      */
 358     @CallerSensitive
 359     public Module addReads(Module other) {
 360         Objects.requireNonNull(other);
 361         if (this.isNamed()) {
 362             Module caller = getCallerModule(Reflection.getCallerClass());
 363             if (caller != this) {
 364                 throw new IllegalCallerException(caller + " != " + this);
 365             }
 366             implAddReads(other, true);
 367         }
 368         return this;
 369     }
 370 
 371     /**
 372      * Updates this module to read another module.
 373      *
 374      * @apiNote Used by the --add-reads command line option.
 375      */
 376     void implAddReads(Module other) {
 377         implAddReads(other, true);
 378     }
 379 
 380     /**
 381      * Updates this module to read all unnamed modules.
 382      *
 383      * @apiNote Used by the --add-reads command line option.
 384      */
 385     void implAddReadsAllUnnamed() {
 386         implAddReads(Module.ALL_UNNAMED_MODULE, true);
 387     }
 388 
 389     /**
 390      * Updates this module to read another module without notifying the VM.
 391      *
 392      * @apiNote This method is for VM white-box testing.
 393      */
 394     void implAddReadsNoSync(Module other) {
 395         implAddReads(other, false);
 396     }
 397 
 398     /**
 399      * Makes the given {@code Module} readable to this module.
 400      *
 401      * If {@code syncVM} is {@code true} then the VM is notified.
 402      */
 403     private void implAddReads(Module other, boolean syncVM) {
 404         Objects.requireNonNull(other);
 405         if (!canRead(other)) {
 406             // update VM first, just in case it fails
 407             if (syncVM) {
 408                 if (other == ALL_UNNAMED_MODULE) {
 409                     addReads0(this, null);
 410                 } else {
 411                     addReads0(this, other);
 412                 }
 413             }
 414 
 415             // add reflective read
 416             ReflectionData.reads.putIfAbsent(this, other, Boolean.TRUE);
 417         }
 418     }
 419 
 420 
 421     // -- exported and open packages --
 422 
 423     // the packages are open to other modules, can be null
 424     // if the value contains EVERYONE_MODULE then the package is open to all
 425     private volatile Map<String, Set<Module>> openPackages;
 426 
 427     // the packages that are exported, can be null
 428     // if the value contains EVERYONE_MODULE then the package is exported to all
 429     private volatile Map<String, Set<Module>> exportedPackages;
 430 
 431     /**
 432      * Returns {@code true} if this module exports the given package to at
 433      * least the given module.
 434      *
 435      * <p> This method returns {@code true} if invoked to test if a package in
 436      * this module is exported to itself. It always returns {@code true} when
 437      * invoked on an unnamed module. A package that is {@link #isOpen open} to
 438      * the given module is considered exported to that module at run-time and
 439      * so this method returns {@code true} if the package is open to the given
 440      * module. </p>
 441      *
 442      * <p> This method does not check if the given module reads this module. </p>
 443      *
 444      * @param  pn
 445      *         The package name
 446      * @param  other
 447      *         The other module
 448      *
 449      * @return {@code true} if this module exports the package to at least the
 450      *         given module
 451      *
 452      * @see ModuleDescriptor#exports()
 453      * @see #addExports(String,Module)
 454      */
 455     public boolean isExported(String pn, Module other) {
 456         Objects.requireNonNull(pn);
 457         Objects.requireNonNull(other);
 458         return implIsExportedOrOpen(pn, other, /*open*/false);
 459     }
 460 
 461     /**
 462      * Returns {@code true} if this module has <em>opened</em> a package to at
 463      * least the given module.
 464      *
 465      * <p> This method returns {@code true} if invoked to test if a package in
 466      * this module is open to itself. It returns {@code true} when invoked on an
 467      * {@link ModuleDescriptor#isOpen open} module with a package in the module.
 468      * It always returns {@code true} when invoked on an unnamed module. </p>
 469      *
 470      * <p> This method does not check if the given module reads this module. </p>
 471      *
 472      * @param  pn
 473      *         The package name
 474      * @param  other
 475      *         The other module
 476      *
 477      * @return {@code true} if this module has <em>opened</em> the package
 478      *         to at least the given module
 479      *
 480      * @see ModuleDescriptor#opens()
 481      * @see #addOpens(String,Module)
 482      * @see AccessibleObject#setAccessible(boolean)
 483      * @see java.lang.invoke.MethodHandles#privateLookupIn
 484      */
 485     public boolean isOpen(String pn, Module other) {
 486         Objects.requireNonNull(pn);
 487         Objects.requireNonNull(other);
 488         return implIsExportedOrOpen(pn, other, /*open*/true);
 489     }
 490 
 491     /**
 492      * Returns {@code true} if this module exports the given package
 493      * unconditionally.
 494      *
 495      * <p> This method always returns {@code true} when invoked on an unnamed
 496      * module. A package that is {@link #isOpen(String) opened} unconditionally
 497      * is considered exported unconditionally at run-time and so this method
 498      * returns {@code true} if the package is opened unconditionally. </p>
 499      *
 500      * <p> This method does not check if the given module reads this module. </p>
 501      *
 502      * @param  pn
 503      *         The package name
 504      *
 505      * @return {@code true} if this module exports the package unconditionally
 506      *
 507      * @see ModuleDescriptor#exports()
 508      */
 509     public boolean isExported(String pn) {
 510         Objects.requireNonNull(pn);
 511         return implIsExportedOrOpen(pn, EVERYONE_MODULE, /*open*/false);
 512     }
 513 
 514     /**
 515      * Returns {@code true} if this module has <em>opened</em> a package
 516      * unconditionally.
 517      *
 518      * <p> This method always returns {@code true} when invoked on an unnamed
 519      * module. Additionally, it always returns {@code true} when invoked on an
 520      * {@link ModuleDescriptor#isOpen open} module with a package in the
 521      * module. </p>
 522      *
 523      * <p> This method does not check if the given module reads this module. </p>
 524      *
 525      * @param  pn
 526      *         The package name
 527      *
 528      * @return {@code true} if this module has <em>opened</em> the package
 529      *         unconditionally
 530      *
 531      * @see ModuleDescriptor#opens()
 532      */
 533     public boolean isOpen(String pn) {
 534         Objects.requireNonNull(pn);
 535         return implIsExportedOrOpen(pn, EVERYONE_MODULE, /*open*/true);
 536     }
 537 
 538 
 539     /**
 540      * Returns {@code true} if this module exports or opens the given package
 541      * to the given module. If the other module is {@code EVERYONE_MODULE} then
 542      * this method tests if the package is exported or opened unconditionally.
 543      */
 544     private boolean implIsExportedOrOpen(String pn, Module other, boolean open) {
 545         // all packages in unnamed modules are open
 546         if (!isNamed())
 547             return true;
 548 
 549         // all packages are exported/open to self
 550         if (other == this && descriptor.packages().contains(pn))
 551             return true;
 552 
 553         // all packages in open and automatic modules are open
 554         if (descriptor.isOpen() || descriptor.isAutomatic())
 555             return descriptor.packages().contains(pn);
 556 
 557         // exported/opened via module declaration/descriptor
 558         if (isStaticallyExportedOrOpen(pn, other, open))
 559             return true;
 560 
 561         // exported via addExports/addOpens
 562         if (isReflectivelyExportedOrOpen(pn, other, open))
 563             return true;
 564 
 565         // not exported or open to other
 566         return false;
 567     }
 568 
 569     /**
 570      * Returns {@code true} if this module exports or opens a package to
 571      * the given module via its module declaration or CLI options.
 572      */
 573     private boolean isStaticallyExportedOrOpen(String pn, Module other, boolean open) {
 574         // test if package is open to everyone or <other>
 575         Map<String, Set<Module>> openPackages = this.openPackages;
 576         if (openPackages != null && allows(openPackages.get(pn), other)) {
 577             return true;
 578         }
 579 
 580         if (!open) {
 581             // test package is exported to everyone or <other>
 582             Map<String, Set<Module>> exportedPackages = this.exportedPackages;
 583             if (exportedPackages != null && allows(exportedPackages.get(pn), other)) {
 584                 return true;
 585             }
 586         }
 587 
 588         return false;
 589     }
 590 
 591     /**
 592      * Returns {@code true} if targets is non-null and contains EVERYONE_MODULE
 593      * or the given module. Also returns true if the given module is an unnamed
 594      * module and targets contains ALL_UNNAMED_MODULE.
 595      */
 596     private boolean allows(Set<Module> targets, Module module) {
 597        if (targets != null) {
 598            if (targets.contains(EVERYONE_MODULE))
 599                return true;
 600            if (module != EVERYONE_MODULE) {
 601                if (targets.contains(module))
 602                    return true;
 603                if (!module.isNamed() && targets.contains(ALL_UNNAMED_MODULE))
 604                    return true;
 605            }
 606         }
 607         return false;
 608     }
 609 
 610     /**
 611      * Returns {@code true} if this module reflectively exports or opens the
 612      * given package to the given module.
 613      */
 614     private boolean isReflectivelyExportedOrOpen(String pn, Module other, boolean open) {
 615         // exported or open to all modules
 616         Map<String, Boolean> exports = ReflectionData.exports.get(this, EVERYONE_MODULE);
 617         if (exports != null) {
 618             Boolean b = exports.get(pn);
 619             if (b != null) {
 620                 boolean isOpen = b.booleanValue();
 621                 if (!open || isOpen) return true;
 622             }
 623         }
 624 
 625         if (other != EVERYONE_MODULE) {
 626 
 627             // exported or open to other
 628             exports = ReflectionData.exports.get(this, other);
 629             if (exports != null) {
 630                 Boolean b = exports.get(pn);
 631                 if (b != null) {
 632                     boolean isOpen = b.booleanValue();
 633                     if (!open || isOpen) return true;
 634                 }
 635             }
 636 
 637             // other is an unnamed module && exported or open to all unnamed
 638             if (!other.isNamed()) {
 639                 exports = ReflectionData.exports.get(this, ALL_UNNAMED_MODULE);
 640                 if (exports != null) {
 641                     Boolean b = exports.get(pn);
 642                     if (b != null) {
 643                         boolean isOpen = b.booleanValue();
 644                         if (!open || isOpen) return true;
 645                     }
 646                 }
 647             }
 648 
 649         }
 650 
 651         return false;
 652     }
 653 
 654     /**
 655      * Returns {@code true} if this module reflectively exports the
 656      * given package to the given module.
 657      */
 658     boolean isReflectivelyExported(String pn, Module other) {
 659         return isReflectivelyExportedOrOpen(pn, other, false);
 660     }
 661 
 662     /**
 663      * Returns {@code true} if this module reflectively opens the
 664      * given package to the given module.
 665      */
 666     boolean isReflectivelyOpened(String pn, Module other) {
 667         return isReflectivelyExportedOrOpen(pn, other, true);
 668     }
 669 
 670 
 671     /**
 672      * If the caller's module is this module then update this module to export
 673      * the given package to the given module.
 674      *
 675      * <p> This method has no effect if the package is already exported (or
 676      * <em>open</em>) to the given module. </p>
 677      *
 678      * @apiNote As specified in section 5.4.3 of the <cite>The Java&trade;
 679      * Virtual Machine Specification </cite>, if an attempt to resolve a
 680      * symbolic reference fails because of a linkage error, then subsequent
 681      * attempts to resolve the reference always fail with the same error that
 682      * was thrown as a result of the initial resolution attempt.
 683      *
 684      * @param  pn
 685      *         The package name
 686      * @param  other
 687      *         The module
 688      *
 689      * @return this module
 690      *
 691      * @throws IllegalArgumentException
 692      *         If {@code pn} is {@code null}, or this is a named module and the
 693      *         package {@code pn} is not a package in this module
 694      * @throws IllegalCallerException
 695      *         If this is a named module and the caller's module is not this
 696      *         module
 697      *
 698      * @jvms 5.4.3 Resolution
 699      * @see #isExported(String,Module)
 700      */
 701     @CallerSensitive
 702     public Module addExports(String pn, Module other) {
 703         if (pn == null)
 704             throw new IllegalArgumentException("package is null");
 705         Objects.requireNonNull(other);
 706 
 707         if (isNamed()) {
 708             Module caller = getCallerModule(Reflection.getCallerClass());
 709             if (caller != this) {
 710                 throw new IllegalCallerException(caller + " != " + this);
 711             }
 712             implAddExportsOrOpens(pn, other, /*open*/false, /*syncVM*/true);
 713         }
 714 
 715         return this;
 716     }
 717 
 718     /**
 719      * If this module has <em>opened</em> a package to at least the caller
 720      * module then update this module to open the package to the given module.
 721      * Opening a package with this method allows all types in the package,
 722      * and all their members, not just public types and their public members,
 723      * to be reflected on by the given module when using APIs that support
 724      * private access or a way to bypass or suppress default Java language
 725      * access control checks.
 726      *
 727      * <p> This method has no effect if the package is already <em>open</em>
 728      * to the given module. </p>
 729      *
 730      * @apiNote This method can be used for cases where a <em>consumer
 731      * module</em> uses a qualified opens to open a package to an <em>API
 732      * module</em> but where the reflective access to the members of classes in
 733      * the consumer module is delegated to code in another module. Code in the
 734      * API module can use this method to open the package in the consumer module
 735      * to the other module.
 736      *
 737      * @param  pn
 738      *         The package name
 739      * @param  other
 740      *         The module
 741      *
 742      * @return this module
 743      *
 744      * @throws IllegalArgumentException
 745      *         If {@code pn} is {@code null}, or this is a named module and the
 746      *         package {@code pn} is not a package in this module
 747      * @throws IllegalCallerException
 748      *         If this is a named module and this module has not opened the
 749      *         package to at least the caller's module
 750      *
 751      * @see #isOpen(String,Module)
 752      * @see AccessibleObject#setAccessible(boolean)
 753      * @see java.lang.invoke.MethodHandles#privateLookupIn
 754      */
 755     @CallerSensitive
 756     public Module addOpens(String pn, Module other) {
 757         if (pn == null)
 758             throw new IllegalArgumentException("package is null");
 759         Objects.requireNonNull(other);
 760 
 761         if (isNamed()) {
 762             Module caller = getCallerModule(Reflection.getCallerClass());
 763             if (caller != this && (caller == null || !isOpen(pn, caller)))
 764                 throw new IllegalCallerException(pn + " is not open to " + caller);
 765             implAddExportsOrOpens(pn, other, /*open*/true, /*syncVM*/true);
 766         }
 767 
 768         return this;
 769     }
 770 
 771 
 772     /**
 773      * Updates this module to export a package unconditionally.
 774      *
 775      * @apiNote This method is for JDK tests only.
 776      */
 777     void implAddExports(String pn) {
 778         implAddExportsOrOpens(pn, Module.EVERYONE_MODULE, false, true);
 779     }
 780 
 781     /**
 782      * Updates this module to export a package to another module.
 783      *
 784      * @apiNote Used by Instrumentation::redefineModule and --add-exports
 785      */
 786     void implAddExports(String pn, Module other) {
 787         implAddExportsOrOpens(pn, other, false, true);
 788     }
 789 
 790     /**
 791      * Updates this module to export a package to all unnamed modules.
 792      *
 793      * @apiNote Used by the --add-exports command line option.
 794      */
 795     void implAddExportsToAllUnnamed(String pn) {
 796         implAddExportsOrOpens(pn, Module.ALL_UNNAMED_MODULE, false, true);
 797     }
 798 
 799     /**
 800      * Updates this export to export a package unconditionally without
 801      * notifying the VM.
 802      *
 803      * @apiNote This method is for VM white-box testing.
 804      */
 805     void implAddExportsNoSync(String pn) {
 806         implAddExportsOrOpens(pn.replace('/', '.'), Module.EVERYONE_MODULE, false, false);
 807     }
 808 
 809     /**
 810      * Updates a module to export a package to another module without
 811      * notifying the VM.
 812      *
 813      * @apiNote This method is for VM white-box testing.
 814      */
 815     void implAddExportsNoSync(String pn, Module other) {
 816         implAddExportsOrOpens(pn.replace('/', '.'), other, false, false);
 817     }
 818 
 819     /**
 820      * Updates this module to open a package unconditionally.
 821      *
 822      * @apiNote This method is for JDK tests only.
 823      */
 824     void implAddOpens(String pn) {
 825         implAddExportsOrOpens(pn, Module.EVERYONE_MODULE, true, true);
 826     }
 827 
 828     /**
 829      * Updates this module to open a package to another module.
 830      *
 831      * @apiNote Used by Instrumentation::redefineModule and --add-opens
 832      */
 833     void implAddOpens(String pn, Module other) {
 834         implAddExportsOrOpens(pn, other, true, true);
 835     }
 836 
 837     /**
 838      * Updates this module to open a package to all unnamed modules.
 839      *
 840      * @apiNote Used by the --add-opens command line option.
 841      */
 842     void implAddOpensToAllUnnamed(String pn) {
 843         implAddExportsOrOpens(pn, Module.ALL_UNNAMED_MODULE, true, true);
 844     }
 845 
 846     /**
 847      * Updates a module to export or open a module to another module.
 848      *
 849      * If {@code syncVM} is {@code true} then the VM is notified.
 850      */
 851     private void implAddExportsOrOpens(String pn,
 852                                        Module other,
 853                                        boolean open,
 854                                        boolean syncVM) {
 855         Objects.requireNonNull(other);
 856         Objects.requireNonNull(pn);
 857 
 858         // all packages are open in unnamed, open, and automatic modules
 859         if (!isNamed() || descriptor.isOpen() || descriptor.isAutomatic())
 860             return;
 861 
 862         // check if the package is already exported/open to other
 863         if (implIsExportedOrOpen(pn, other, open)) {
 864 
 865             // if the package is exported/open for illegal access then we need
 866             // to record that it has also been exported/opened reflectively so
 867             // that the IllegalAccessLogger doesn't emit a warning.
 868             boolean needToAdd = false;
 869             if (!other.isNamed()) {
 870                 IllegalAccessLogger l = IllegalAccessLogger.illegalAccessLogger();
 871                 if (l != null) {
 872                     if (open) {
 873                         needToAdd = l.isOpenForIllegalAccess(this, pn);
 874                     } else {
 875                         needToAdd = l.isExportedForIllegalAccess(this, pn);
 876                     }
 877                 }
 878             }
 879             if (!needToAdd) {
 880                 // nothing to do
 881                 return;
 882             }
 883         }
 884 
 885         // can only export a package in the module
 886         if (!descriptor.packages().contains(pn)) {
 887             throw new IllegalArgumentException("package " + pn
 888                                                + " not in contents");
 889         }
 890 
 891         // update VM first, just in case it fails
 892         if (syncVM) {
 893             if (other == EVERYONE_MODULE) {
 894                 addExportsToAll0(this, pn);
 895             } else if (other == ALL_UNNAMED_MODULE) {
 896                 addExportsToAllUnnamed0(this, pn);
 897             } else {
 898                 addExports0(this, pn, other);
 899             }
 900         }
 901 
 902         // add package name to exports if absent
 903         Map<String, Boolean> map = ReflectionData.exports
 904             .computeIfAbsent(this, other,
 905                              (m1, m2) -> new ConcurrentHashMap<>());
 906         if (open) {
 907             map.put(pn, Boolean.TRUE);  // may need to promote from FALSE to TRUE
 908         } else {
 909             map.putIfAbsent(pn, Boolean.FALSE);
 910         }
 911     }
 912 
 913     /**
 914      * Updates a module to open all packages returned by the given iterator to
 915      * all unnamed modules.
 916      *
 917      * @apiNote Used during startup to open packages for illegal access.
 918      */
 919     void implAddOpensToAllUnnamed(Iterator<String> iterator) {
 920         if (jdk.internal.misc.VM.isModuleSystemInited()) {
 921             throw new IllegalStateException("Module system already initialized");
 922         }
 923 
 924         // replace this module's openPackages map with a new map that opens
 925         // the packages to all unnamed modules.
 926         Map<String, Set<Module>> openPackages = this.openPackages;
 927         if (openPackages == null) {
 928             openPackages = new HashMap<>();
 929         } else {
 930             openPackages = new HashMap<>(openPackages);
 931         }
 932         while (iterator.hasNext()) {
 933             String pn = iterator.next();
 934             Set<Module> prev = openPackages.putIfAbsent(pn, ALL_UNNAMED_MODULE_SET);
 935             if (prev != null) {
 936                 prev.add(ALL_UNNAMED_MODULE);
 937             }
 938 
 939             // update VM to export the package
 940             addExportsToAllUnnamed0(this, pn);
 941         }
 942         this.openPackages = openPackages;
 943     }
 944 
 945 
 946     // -- services --
 947 
 948     /**
 949      * If the caller's module is this module then update this module to add a
 950      * service dependence on the given service type. This method is intended
 951      * for use by frameworks that invoke {@link java.util.ServiceLoader
 952      * ServiceLoader} on behalf of other modules or where the framework is
 953      * passed a reference to the service type by other code. This method is
 954      * a no-op when invoked on an unnamed module or an automatic module.
 955      *
 956      * <p> This method does not cause {@link Configuration#resolveAndBind
 957      * resolveAndBind} to be re-run. </p>
 958      *
 959      * @param  service
 960      *         The service type
 961      *
 962      * @return this module
 963      *
 964      * @throws IllegalCallerException
 965      *         If this is a named module and the caller's module is not this
 966      *         module
 967      *
 968      * @see #canUse(Class)
 969      * @see ModuleDescriptor#uses()
 970      */
 971     @CallerSensitive
 972     public Module addUses(Class<?> service) {
 973         Objects.requireNonNull(service);
 974 
 975         if (isNamed() && !descriptor.isAutomatic()) {
 976             Module caller = getCallerModule(Reflection.getCallerClass());
 977             if (caller != this) {
 978                 throw new IllegalCallerException(caller + " != " + this);
 979             }
 980             implAddUses(service);
 981         }
 982 
 983         return this;
 984     }
 985 
 986     /**
 987      * Update this module to add a service dependence on the given service
 988      * type.
 989      */
 990     void implAddUses(Class<?> service) {
 991         if (!canUse(service)) {
 992             ReflectionData.uses.putIfAbsent(this, service, Boolean.TRUE);
 993         }
 994     }
 995 
 996 
 997     /**
 998      * Indicates if this module has a service dependence on the given service
 999      * type. This method always returns {@code true} when invoked on an unnamed
1000      * module or an automatic module.
1001      *
1002      * @param  service
1003      *         The service type
1004      *
1005      * @return {@code true} if this module uses service type {@code st}
1006      *
1007      * @see #addUses(Class)
1008      */
1009     public boolean canUse(Class<?> service) {
1010         Objects.requireNonNull(service);
1011 
1012         if (!isNamed())
1013             return true;
1014 
1015         if (descriptor.isAutomatic())
1016             return true;
1017 
1018         // uses was declared
1019         if (descriptor.uses().contains(service.getName()))
1020             return true;
1021 
1022         // uses added via addUses
1023         return ReflectionData.uses.containsKeyPair(this, service);
1024     }
1025 
1026 
1027 
1028     // -- packages --
1029 
1030     /**
1031      * Returns the set of package names for the packages in this module.
1032      *
1033      * <p> For named modules, the returned set contains an element for each
1034      * package in the module. </p>
1035      *
1036      * <p> For unnamed modules, this method is the equivalent to invoking the
1037      * {@link ClassLoader#getDefinedPackages() getDefinedPackages} method of
1038      * this module's class loader and returning the set of package names. </p>
1039      *
1040      * @return the set of the package names of the packages in this module
1041      */
1042     public Set<String> getPackages() {
1043         if (isNamed()) {
1044             return descriptor.packages();
1045         } else {
1046             // unnamed module
1047             Stream<Package> packages;
1048             if (loader == null) {
1049                 packages = BootLoader.packages();
1050             } else {
1051                 packages = loader.packages();
1052             }
1053             return packages.map(Package::getName).collect(Collectors.toSet());
1054         }
1055     }
1056 
1057 
1058     // -- creating Module objects --
1059 
1060     /**
1061      * Defines all module in a configuration to the runtime.
1062      *
1063      * @return a map of module name to runtime {@code Module}
1064      *
1065      * @throws IllegalArgumentException
1066      *         If defining any of the modules to the VM fails
1067      */
1068     static Map<String, Module> defineModules(Configuration cf,
1069                                              Function<String, ClassLoader> clf,
1070                                              ModuleLayer layer)
1071     {
1072         boolean isBootLayer = (ModuleLayer.boot() == null);
1073 
1074         int cap = (int)(cf.modules().size() / 0.75f + 1.0f);
1075         Map<String, Module> nameToModule = new HashMap<>(cap);
1076         Map<String, ClassLoader> nameToLoader = new HashMap<>(cap);
1077 
1078         Set<ClassLoader> loaders = new HashSet<>();
1079         boolean hasPlatformModules = false;
1080 
1081         // map each module to a class loader
1082         for (ResolvedModule resolvedModule : cf.modules()) {
1083             String name = resolvedModule.name();
1084             ClassLoader loader = clf.apply(name);
1085             nameToLoader.put(name, loader);
1086             if (loader == null || loader == ClassLoaders.platformClassLoader()) {
1087                 if (!(clf instanceof ModuleLoaderMap.Mapper)) {
1088                     throw new IllegalArgumentException("loader can't be 'null'"
1089                             + " or the platform class loader");
1090                 }
1091                 hasPlatformModules = true;
1092             } else {
1093                 loaders.add(loader);
1094             }
1095         }
1096 
1097         // define each module in the configuration to the VM
1098         for (ResolvedModule resolvedModule : cf.modules()) {
1099             ModuleReference mref = resolvedModule.reference();
1100             ModuleDescriptor descriptor = mref.descriptor();
1101             String name = descriptor.name();
1102             ClassLoader loader = nameToLoader.get(name);
1103             Module m;
1104             if (loader == null && name.equals("java.base")) {
1105                 // java.base is already defined to the VM
1106                 m = Object.class.getModule();
1107             } else {
1108                 URI uri = mref.location().orElse(null);
1109                 m = new Module(layer, loader, descriptor, uri);
1110             }
1111             nameToModule.put(name, m);
1112         }
1113 
1114         // setup readability and exports/opens
1115         for (ResolvedModule resolvedModule : cf.modules()) {
1116             ModuleReference mref = resolvedModule.reference();
1117             ModuleDescriptor descriptor = mref.descriptor();
1118 
1119             String mn = descriptor.name();
1120             Module m = nameToModule.get(mn);
1121             assert m != null;
1122 
1123             // reads
1124             Set<Module> reads = new HashSet<>();
1125 
1126             // name -> source Module when in parent layer
1127             Map<String, Module> nameToSource = Collections.emptyMap();
1128 
1129             for (ResolvedModule other : resolvedModule.reads()) {
1130                 Module m2 = null;
1131                 if (other.configuration() == cf) {
1132                     // this configuration
1133                     m2 = nameToModule.get(other.name());
1134                     assert m2 != null;
1135                 } else {
1136                     // parent layer
1137                     for (ModuleLayer parent: layer.parents()) {
1138                         m2 = findModule(parent, other);
1139                         if (m2 != null)
1140                             break;
1141                     }
1142                     assert m2 != null;
1143                     if (nameToSource.isEmpty())
1144                         nameToSource = new HashMap<>();
1145                     nameToSource.put(other.name(), m2);
1146                 }
1147                 reads.add(m2);
1148 
1149                 // update VM view
1150                 addReads0(m, m2);
1151             }
1152             m.reads = reads;
1153 
1154             // automatic modules read all unnamed modules
1155             if (descriptor.isAutomatic()) {
1156                 m.implAddReads(ALL_UNNAMED_MODULE, true);
1157             }
1158 
1159             // exports and opens, skipped for open and automatic
1160             if (!descriptor.isOpen() && !descriptor.isAutomatic()) {
1161                 if (isBootLayer && descriptor.opens().isEmpty()) {
1162                     // no open packages, no qualified exports to modules in parent layers
1163                     initExports(m, nameToModule);
1164                 } else {
1165                     initExportsAndOpens(m, nameToSource, nameToModule, layer.parents());
1166                 }
1167             }
1168         }
1169 
1170         // if there are modules defined to the boot or platform class loaders
1171         // then register the modules in the class loader's services catalog
1172         if (hasPlatformModules) {
1173             ClassLoader pcl = ClassLoaders.platformClassLoader();
1174             ServicesCatalog bootCatalog = BootLoader.getServicesCatalog();
1175             ServicesCatalog pclCatalog = ServicesCatalog.getServicesCatalog(pcl);
1176             for (ResolvedModule resolvedModule : cf.modules()) {
1177                 ModuleReference mref = resolvedModule.reference();
1178                 ModuleDescriptor descriptor = mref.descriptor();
1179                 if (!descriptor.provides().isEmpty()) {
1180                     String name = descriptor.name();
1181                     Module m = nameToModule.get(name);
1182                     ClassLoader loader = nameToLoader.get(name);
1183                     if (loader == null) {
1184                         bootCatalog.register(m);
1185                     } else if (loader == pcl) {
1186                         pclCatalog.register(m);
1187                     }
1188                 }
1189             }
1190         }
1191 
1192         // record that there is a layer with modules defined to the class loader
1193         for (ClassLoader loader : loaders) {
1194             layer.bindToLoader(loader);
1195         }
1196 
1197         return nameToModule;
1198     }
1199 
1200     /**
1201      * Find the runtime Module corresponding to the given ResolvedModule
1202      * in the given parent layer (or its parents).
1203      */
1204     private static Module findModule(ModuleLayer parent,
1205                                      ResolvedModule resolvedModule) {
1206         Configuration cf = resolvedModule.configuration();
1207         String dn = resolvedModule.name();
1208         return parent.layers()
1209                 .filter(l -> l.configuration() == cf)
1210                 .findAny()
1211                 .map(layer -> {
1212                     Optional<Module> om = layer.findModule(dn);
1213                     assert om.isPresent() : dn + " not found in layer";
1214                     Module m = om.get();
1215                     assert m.getLayer() == layer : m + " not in expected layer";
1216                     return m;
1217                 })
1218                 .orElse(null);
1219     }
1220 
1221     /**
1222      * Initialize/setup a module's exports.
1223      *
1224      * @param m the module
1225      * @param nameToModule map of module name to Module (for qualified exports)
1226      */
1227     private static void initExports(Module m, Map<String, Module> nameToModule) {
1228         Map<String, Set<Module>> exportedPackages = new HashMap<>();
1229 
1230         for (Exports exports : m.getDescriptor().exports()) {
1231             String source = exports.source();
1232             if (exports.isQualified()) {
1233                 // qualified exports
1234                 Set<Module> targets = new HashSet<>();
1235                 for (String target : exports.targets()) {
1236                     Module m2 = nameToModule.get(target);
1237                     if (m2 != null) {
1238                         addExports0(m, source, m2);
1239                         targets.add(m2);
1240                     }
1241                 }
1242                 if (!targets.isEmpty()) {
1243                     exportedPackages.put(source, targets);
1244                 }
1245             } else {
1246                 // unqualified exports
1247                 addExportsToAll0(m, source);
1248                 exportedPackages.put(source, EVERYONE_SET);
1249             }
1250         }
1251 
1252         if (!exportedPackages.isEmpty())
1253             m.exportedPackages = exportedPackages;
1254     }
1255 
1256     /**
1257      * Initialize/setup a module's exports.
1258      *
1259      * @param m the module
1260      * @param nameToSource map of module name to Module for modules that m reads
1261      * @param nameToModule map of module name to Module for modules in the layer
1262      *                     under construction
1263      * @param parents the parent layers
1264      */
1265     private static void initExportsAndOpens(Module m,
1266                                             Map<String, Module> nameToSource,
1267                                             Map<String, Module> nameToModule,
1268                                             List<ModuleLayer> parents) {
1269         ModuleDescriptor descriptor = m.getDescriptor();
1270         Map<String, Set<Module>> openPackages = new HashMap<>();
1271         Map<String, Set<Module>> exportedPackages = new HashMap<>();
1272 
1273         // process the open packages first
1274         for (Opens opens : descriptor.opens()) {
1275             String source = opens.source();
1276 
1277             if (opens.isQualified()) {
1278                 // qualified opens
1279                 Set<Module> targets = new HashSet<>();
1280                 for (String target : opens.targets()) {
1281                     Module m2 = findModule(target, nameToSource, nameToModule, parents);
1282                     if (m2 != null) {
1283                         addExports0(m, source, m2);
1284                         targets.add(m2);
1285                     }
1286                 }
1287                 if (!targets.isEmpty()) {
1288                     openPackages.put(source, targets);
1289                 }
1290             } else {
1291                 // unqualified opens
1292                 addExportsToAll0(m, source);
1293                 openPackages.put(source, EVERYONE_SET);
1294             }
1295         }
1296 
1297         // next the exports, skipping exports when the package is open
1298         for (Exports exports : descriptor.exports()) {
1299             String source = exports.source();
1300 
1301             // skip export if package is already open to everyone
1302             Set<Module> openToTargets = openPackages.get(source);
1303             if (openToTargets != null && openToTargets.contains(EVERYONE_MODULE))
1304                 continue;
1305 
1306             if (exports.isQualified()) {
1307                 // qualified exports
1308                 Set<Module> targets = new HashSet<>();
1309                 for (String target : exports.targets()) {
1310                     Module m2 = findModule(target, nameToSource, nameToModule, parents);
1311                     if (m2 != null) {
1312                         // skip qualified export if already open to m2
1313                         if (openToTargets == null || !openToTargets.contains(m2)) {
1314                             addExports0(m, source, m2);
1315                             targets.add(m2);
1316                         }
1317                     }
1318                 }
1319                 if (!targets.isEmpty()) {
1320                     exportedPackages.put(source, targets);
1321                 }
1322             } else {
1323                 // unqualified exports
1324                 addExportsToAll0(m, source);
1325                 exportedPackages.put(source, EVERYONE_SET);
1326             }
1327         }
1328 
1329         if (!openPackages.isEmpty())
1330             m.openPackages = openPackages;
1331         if (!exportedPackages.isEmpty())
1332             m.exportedPackages = exportedPackages;
1333     }
1334 
1335     /**
1336      * Find the runtime Module with the given name. The module name is the
1337      * name of a target module in a qualified exports or opens directive.
1338      *
1339      * @param target The target module to find
1340      * @param nameToSource The modules in parent layers that are read
1341      * @param nameToModule The modules in the layer under construction
1342      * @param parents The parent layers
1343      */
1344     private static Module findModule(String target,
1345                                      Map<String, Module> nameToSource,
1346                                      Map<String, Module> nameToModule,
1347                                      List<ModuleLayer> parents) {
1348         Module m = nameToSource.get(target);
1349         if (m == null) {
1350             m = nameToModule.get(target);
1351             if (m == null) {
1352                 for (ModuleLayer parent : parents) {
1353                     m = parent.findModule(target).orElse(null);
1354                     if (m != null) break;
1355                 }
1356             }
1357         }
1358         return m;
1359     }
1360 
1361 
1362     // -- annotations --
1363 
1364     /**
1365      * {@inheritDoc}
1366      * This method returns {@code null} when invoked on an unnamed module.
1367      */
1368     @Override
1369     public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
1370         return moduleInfoClass().getDeclaredAnnotation(annotationClass);
1371     }
1372 
1373     /**
1374      * {@inheritDoc}
1375      * This method returns an empty array when invoked on an unnamed module.
1376      */
1377     @Override
1378     public Annotation[] getAnnotations() {
1379         return moduleInfoClass().getAnnotations();
1380     }
1381 
1382     /**
1383      * {@inheritDoc}
1384      * This method returns an empty array when invoked on an unnamed module.
1385      */
1386     @Override
1387     public Annotation[] getDeclaredAnnotations() {
1388         return moduleInfoClass().getDeclaredAnnotations();
1389     }
1390 
1391     // cached class file with annotations
1392     private volatile Class<?> moduleInfoClass;
1393 
1394     private Class<?> moduleInfoClass() {
1395         Class<?> clazz = this.moduleInfoClass;
1396         if (clazz != null)
1397             return clazz;
1398 
1399         synchronized (this) {
1400             clazz = this.moduleInfoClass;
1401             if (clazz == null) {
1402                 if (isNamed()) {
1403                     PrivilegedAction<Class<?>> pa = this::loadModuleInfoClass;
1404                     clazz = AccessController.doPrivileged(pa);
1405                 }
1406                 if (clazz == null) {
1407                     class DummyModuleInfo { }
1408                     clazz = DummyModuleInfo.class;
1409                 }
1410                 this.moduleInfoClass = clazz;
1411             }
1412             return clazz;
1413         }
1414     }
1415 
1416     private Class<?> loadModuleInfoClass() {
1417         Class<?> clazz = null;
1418         try (InputStream in = getResourceAsStream("module-info.class")) {
1419             if (in != null)
1420                 clazz = loadModuleInfoClass(in);
1421         } catch (Exception ignore) { }
1422         return clazz;
1423     }
1424 
1425     /**
1426      * Loads module-info.class as a package-private interface in a class loader
1427      * that is a child of this module's class loader.
1428      */
1429     private Class<?> loadModuleInfoClass(InputStream in) throws IOException {
1430         final String MODULE_INFO = "module-info";
1431 
1432         ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS
1433                                          + ClassWriter.COMPUTE_FRAMES);
1434 
1435         ClassVisitor cv = new ClassVisitor(Opcodes.ASM5, cw) {
1436             @Override
1437             public void visit(int version,
1438                               int access,
1439                               String name,
1440                               String signature,
1441                               String superName,
1442                               String[] interfaces) {
1443                 cw.visit(version,
1444                         Opcodes.ACC_INTERFACE
1445                             + Opcodes.ACC_ABSTRACT
1446                             + Opcodes.ACC_SYNTHETIC,
1447                         MODULE_INFO,
1448                         null,
1449                         "java/lang/Object",
1450                         null);
1451             }
1452             @Override
1453             public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
1454                 // keep annotations
1455                 return super.visitAnnotation(desc, visible);
1456             }
1457             @Override
1458             public void visitAttribute(Attribute attr) {
1459                 // drop non-annotation attributes
1460             }
1461         };
1462 
1463         ClassReader cr = new ClassReader(in);
1464         cr.accept(cv, 0);
1465         byte[] bytes = cw.toByteArray();
1466 
1467         ClassLoader cl = new ClassLoader(loader) {
1468             @Override
1469             protected Class<?> findClass(String cn)throws ClassNotFoundException {
1470                 if (cn.equals(MODULE_INFO)) {
1471                     return super.defineClass(cn, bytes, 0, bytes.length);
1472                 } else {
1473                     throw new ClassNotFoundException(cn);
1474                 }
1475             }
1476         };
1477 
1478         try {
1479             return cl.loadClass(MODULE_INFO);
1480         } catch (ClassNotFoundException e) {
1481             throw new InternalError(e);
1482         }
1483     }
1484 
1485 
1486     // -- misc --
1487 
1488 
1489     /**
1490      * Returns an input stream for reading a resource in this module.
1491      * The {@code name} parameter is a {@code '/'}-separated path name that
1492      * identifies the resource. As with {@link Class#getResourceAsStream
1493      * Class.getResourceAsStream}, this method delegates to the module's class
1494      * loader {@link ClassLoader#findResource(String,String)
1495      * findResource(String,String)} method, invoking it with the module name
1496      * (or {@code null} when the module is unnamed) and the name of the
1497      * resource. If the resource name has a leading slash then it is dropped
1498      * before delegation.
1499      *
1500      * <p> A resource in a named module may be <em>encapsulated</em> so that
1501      * it cannot be located by code in other modules. Whether a resource can be
1502      * located or not is determined as follows: </p>
1503      *
1504      * <ul>
1505      *     <li> If the resource name ends with  "{@code .class}" then it is not
1506      *     encapsulated. </li>
1507      *
1508      *     <li> A <em>package name</em> is derived from the resource name. If
1509      *     the package name is a {@linkplain #getPackages() package} in the
1510      *     module then the resource can only be located by the caller of this
1511      *     method when the package is {@linkplain #isOpen(String,Module) open}
1512      *     to at least the caller's module. If the resource is not in a
1513      *     package in the module then the resource is not encapsulated. </li>
1514      * </ul>
1515      *
1516      * <p> In the above, the <em>package name</em> for a resource is derived
1517      * from the subsequence of characters that precedes the last {@code '/'} in
1518      * the name and then replacing each {@code '/'} character in the subsequence
1519      * with {@code '.'}. A leading slash is ignored when deriving the package
1520      * name. As an example, the package name derived for a resource named
1521      * "{@code a/b/c/foo.properties}" is "{@code a.b.c}". A resource name
1522      * with the name "{@code META-INF/MANIFEST.MF}" is never encapsulated
1523      * because "{@code META-INF}" is not a legal package name. </p>
1524      *
1525      * <p> This method returns {@code null} if the resource is not in this
1526      * module, the resource is encapsulated and cannot be located by the caller,
1527      * or access to the resource is denied by the security manager. </p>
1528      *
1529      * @param  name
1530      *         The resource name
1531      *
1532      * @return An input stream for reading the resource or {@code null}
1533      *
1534      * @throws IOException
1535      *         If an I/O error occurs
1536      *
1537      * @see Class#getResourceAsStream(String)
1538      */
1539     @CallerSensitive
1540     public InputStream getResourceAsStream(String name) throws IOException {
1541         if (name.startsWith("/")) {
1542             name = name.substring(1);
1543         }
1544 
1545         if (isNamed() && Resources.canEncapsulate(name)) {
1546             Module caller = getCallerModule(Reflection.getCallerClass());
1547             if (caller != this && caller != Object.class.getModule()) {
1548                 String pn = Resources.toPackageName(name);
1549                 if (getPackages().contains(pn)) {
1550                     if (caller == null && !isOpen(pn)) {
1551                         // no caller, package not open
1552                         return null;
1553                     }
1554                     if (!isOpen(pn, caller)) {
1555                         // package not open to caller
1556                         return null;
1557                     }
1558                 }
1559             }
1560         }
1561 
1562         String mn = this.name;
1563 
1564         // special-case built-in class loaders to avoid URL connection
1565         if (loader == null) {
1566             return BootLoader.findResourceAsStream(mn, name);
1567         } else if (loader instanceof BuiltinClassLoader) {
1568             return ((BuiltinClassLoader) loader).findResourceAsStream(mn, name);
1569         }
1570 
1571         // locate resource in module
1572         URL url = loader.findResource(mn, name);
1573         if (url != null) {
1574             try {
1575                 return url.openStream();
1576             } catch (SecurityException e) { }
1577         }
1578 
1579         return null;
1580     }
1581 
1582     /**
1583      * Returns the string representation of this module. For a named module,
1584      * the representation is the string {@code "module"}, followed by a space,
1585      * and then the module name. For an unnamed module, the representation is
1586      * the string {@code "unnamed module"}, followed by a space, and then an
1587      * implementation specific string that identifies the unnamed module.
1588      *
1589      * @return The string representation of this module
1590      */
1591     @Override
1592     public String toString() {
1593         if (isNamed()) {
1594             return "module " + name;
1595         } else {
1596             String id = Integer.toHexString(System.identityHashCode(this));
1597             return "unnamed module @" + id;
1598         }
1599     }
1600 
1601     /**
1602      * Returns the module that a given caller class is a member of. Returns
1603      * {@code null} if the caller is {@code null}.
1604      */
1605     private Module getCallerModule(Class<?> caller) {
1606         return (caller != null) ? caller.getModule() : null;
1607     }
1608 
1609 
1610     // -- native methods --
1611 
1612     // JVM_DefineModule
1613     private static native void defineModule0(Module module,
1614                                              boolean isOpen,
1615                                              String version,
1616                                              String location,
1617                                              String[] pns);
1618 
1619     // JVM_AddReadsModule
1620     private static native void addReads0(Module from, Module to);
1621 
1622     // JVM_AddModuleExports
1623     private static native void addExports0(Module from, String pn, Module to);
1624 
1625     // JVM_AddModuleExportsToAll
1626     private static native void addExportsToAll0(Module from, String pn);
1627 
1628     // JVM_AddModuleExportsToAllUnnamed
1629     private static native void addExportsToAllUnnamed0(Module from, String pn);
1630 }