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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
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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).
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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.HashMap;
44 import java.util.HashSet;
45 import java.util.Iterator;
46 import java.util.List;
47 import java.util.Map;
48 import java.util.Objects;
49 import java.util.Optional;
50 import java.util.Set;
51 import java.util.concurrent.ConcurrentHashMap;
52 import java.util.function.Function;
53 import java.util.stream.Collectors;
54 import java.util.stream.Stream;
55 
56 import jdk.internal.loader.BuiltinClassLoader;
57 import jdk.internal.loader.BootLoader;
58 import jdk.internal.loader.ClassLoaders;
59 import jdk.internal.module.IllegalAccessLogger;
60 import jdk.internal.module.ModuleLoaderMap;
61 import jdk.internal.module.ServicesCatalog;
62 import jdk.internal.module.Resources;
63 import jdk.internal.org.objectweb.asm.AnnotationVisitor;
64 import jdk.internal.org.objectweb.asm.Attribute;
65 import jdk.internal.org.objectweb.asm.ClassReader;
66 import jdk.internal.org.objectweb.asm.ClassVisitor;
67 import jdk.internal.org.objectweb.asm.ClassWriter;
68 import jdk.internal.org.objectweb.asm.ModuleVisitor;
69 import jdk.internal.org.objectweb.asm.Opcodes;
70 import jdk.internal.reflect.CallerSensitive;
71 import jdk.internal.reflect.Reflection;
72 import sun.security.util.SecurityConstants;
73 
74 /**
75  * Represents a run-time module, either {@link #isNamed() named} or unnamed.
76  *
77  * <p> Named modules have a {@link #getName() name} and are constructed by the
78  * Java Virtual Machine when a graph of modules is defined to the Java virtual
79  * machine to create a {@linkplain ModuleLayer module layer}. </p>
80  *
81  * <p> An unnamed module does not have a name. There is an unnamed module for
82  * each {@link ClassLoader ClassLoader}, obtained by invoking its {@link
83  * ClassLoader#getUnnamedModule() getUnnamedModule} method. All types that are
84  * not in a named module are members of their defining class loader's unnamed
85  * module. </p>
86  *
87  * <p> The package names that are parameters or returned by methods defined in
88  * this class are the fully-qualified names of the packages as defined in
89  * section 6.5.3 of <cite>The Java&trade; Language Specification</cite>, for
90  * example, {@code "java.lang"}. </p>
91  *
92  * <p> Unless otherwise specified, passing a {@code null} argument to a method
93  * in this class causes a {@link NullPointerException NullPointerException} to
94  * be thrown. </p>
95  *
96  * @since 9
97  * @spec JPMS
98  * @see Class#getModule()
99  */
100 
101 public final class Module implements AnnotatedElement {
102 
103     // the layer that contains this module, can be null
104     private final ModuleLayer layer;
105 
106     // module name and loader, these fields are read by VM
107     private final String name;
108     private final ClassLoader loader;
109 
110     // the module descriptor
111     private final ModuleDescriptor descriptor;
112 
113 
114     /**
115      * Creates a new named Module. The resulting Module will be defined to the
116      * VM but will not read any other modules, will not have any exports setup
117      * and will not be registered in the service catalog.
118      */
Module(ModuleLayer layer, ClassLoader loader, ModuleDescriptor descriptor, URI uri)119     Module(ModuleLayer layer,
120            ClassLoader loader,
121            ModuleDescriptor descriptor,
122            URI uri)
123     {
124         this.layer = layer;
125         this.name = descriptor.name();
126         this.loader = loader;
127         this.descriptor = descriptor;
128 
129         // define module to VM
130 
131         boolean isOpen = descriptor.isOpen() || descriptor.isAutomatic();
132         Version version = descriptor.version().orElse(null);
133         String vs = Objects.toString(version, null);
134         String loc = Objects.toString(uri, null);
135         String[] packages = descriptor.packages().toArray(new String[0]);
136         defineModule0(this, isOpen, vs, loc, packages);
137     }
138 
139 
140     /**
141      * Create the unnamed Module for the given ClassLoader.
142      *
143      * @see ClassLoader#getUnnamedModule
144      */
Module(ClassLoader loader)145     Module(ClassLoader loader) {
146         this.layer = null;
147         this.name = null;
148         this.loader = loader;
149         this.descriptor = null;
150     }
151 
152 
153     /**
154      * Creates a named module but without defining the module to the VM.
155      *
156      * @apiNote This constructor is for VM white-box testing.
157      */
Module(ClassLoader loader, ModuleDescriptor descriptor)158     Module(ClassLoader loader, ModuleDescriptor descriptor) {
159         this.layer = null;
160         this.name = descriptor.name();
161         this.loader = loader;
162         this.descriptor = descriptor;
163     }
164 
165 
166     /**
167      * Returns {@code true} if this module is a named module.
168      *
169      * @return {@code true} if this is a named module
170      *
171      * @see ClassLoader#getUnnamedModule()
172      */
isNamed()173     public boolean isNamed() {
174         return name != null;
175     }
176 
177     /**
178      * Returns the module name or {@code null} if this module is an unnamed
179      * module.
180      *
181      * @return The module name
182      */
getName()183     public String getName() {
184         return name;
185     }
186 
187     /**
188      * Returns the {@code ClassLoader} for this module.
189      *
190      * <p> If there is a security manager then its {@code checkPermission}
191      * method if first called with a {@code RuntimePermission("getClassLoader")}
192      * permission to check that the caller is allowed to get access to the
193      * class loader. </p>
194      *
195      * @return The class loader for this module
196      *
197      * @throws SecurityException
198      *         If denied by the security manager
199      */
getClassLoader()200     public ClassLoader getClassLoader() {
201         SecurityManager sm = System.getSecurityManager();
202         if (sm != null) {
203             sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
204         }
205         return loader;
206     }
207 
208     /**
209      * Returns the module descriptor for this module or {@code null} if this
210      * module is an unnamed module.
211      *
212      * @return The module descriptor for this module
213      */
getDescriptor()214     public ModuleDescriptor getDescriptor() {
215         return descriptor;
216     }
217 
218     /**
219      * Returns the module layer that contains this module or {@code null} if
220      * this module is not in a module layer.
221      *
222      * A module layer contains named modules and therefore this method always
223      * returns {@code null} when invoked on an unnamed module.
224      *
225      * <p> <a href="reflect/Proxy.html#dynamicmodule">Dynamic modules</a> are
226      * named modules that are generated at runtime. A dynamic module may or may
227      * not be in a module layer. </p>
228      *
229      * @return The module layer that contains this module
230      *
231      * @see java.lang.reflect.Proxy
232      */
getLayer()233     public ModuleLayer getLayer() {
234         if (isNamed()) {
235             ModuleLayer layer = this.layer;
236             if (layer != null)
237                 return layer;
238 
239             // special-case java.base as it is created before the boot layer
240             if (loader == null && name.equals("java.base")) {
241                 return ModuleLayer.boot();
242             }
243         }
244         return null;
245     }
246 
247     // --
248 
249     // special Module to mean "all unnamed modules"
250     private static final Module ALL_UNNAMED_MODULE = new Module(null);
251     private static final Set<Module> ALL_UNNAMED_MODULE_SET = Set.of(ALL_UNNAMED_MODULE);
252 
253     // special Module to mean "everyone"
254     private static final Module EVERYONE_MODULE = new Module(null);
255     private static final Set<Module> EVERYONE_SET = Set.of(EVERYONE_MODULE);
256 
257     /**
258      * The holder of data structures to support readability, exports, and
259      * service use added at runtime with the reflective APIs.
260      */
261     private static class ReflectionData {
262         /**
263          * A module (1st key) reads another module (2nd key)
264          */
265         static final WeakPairMap<Module, Module, Boolean> reads =
266             new WeakPairMap<>();
267 
268         /**
269          * A module (1st key) exports or opens a package to another module
270          * (2nd key). The map value is a map of package name to a boolean
271          * that indicates if the package is opened.
272          */
273         static final WeakPairMap<Module, Module, Map<String, Boolean>> exports =
274             new WeakPairMap<>();
275 
276         /**
277          * A module (1st key) uses a service (2nd key)
278          */
279         static final WeakPairMap<Module, Class<?>, Boolean> uses =
280             new WeakPairMap<>();
281     }
282 
283 
284     // -- readability --
285 
286     // the modules that this module reads
287     private volatile Set<Module> reads;
288 
289     /**
290      * Indicates if this module reads the given module. This method returns
291      * {@code true} if invoked to test if this module reads itself. It also
292      * returns {@code true} if invoked on an unnamed module (as unnamed
293      * modules read all modules).
294      *
295      * @param  other
296      *         The other module
297      *
298      * @return {@code true} if this module reads {@code other}
299      *
300      * @see #addReads(Module)
301      */
canRead(Module other)302     public boolean canRead(Module other) {
303         Objects.requireNonNull(other);
304 
305         // an unnamed module reads all modules
306         if (!this.isNamed())
307             return true;
308 
309         // all modules read themselves
310         if (other == this)
311             return true;
312 
313         // check if this module reads other
314         if (other.isNamed()) {
315             Set<Module> reads = this.reads; // volatile read
316             if (reads != null && reads.contains(other))
317                 return true;
318         }
319 
320         // check if this module reads the other module reflectively
321         if (ReflectionData.reads.containsKeyPair(this, other))
322             return true;
323 
324         // if other is an unnamed module then check if this module reads
325         // all unnamed modules
326         if (!other.isNamed()
327             && ReflectionData.reads.containsKeyPair(this, ALL_UNNAMED_MODULE))
328             return true;
329 
330         return false;
331     }
332 
333     /**
334      * If the caller's module is this module then update this module to read
335      * the given module.
336      *
337      * This method is a no-op if {@code other} is this module (all modules read
338      * themselves), this module is an unnamed module (as unnamed modules read
339      * all modules), or this module already reads {@code other}.
340      *
341      * @implNote <em>Read edges</em> added by this method are <em>weak</em> and
342      * do not prevent {@code other} from being GC'ed when this module is
343      * strongly reachable.
344      *
345      * @param  other
346      *         The other module
347      *
348      * @return this module
349      *
350      * @throws IllegalCallerException
351      *         If this is a named module and the caller's module is not this
352      *         module
353      *
354      * @see #canRead
355      */
356     @CallerSensitive
addReads(Module other)357     public Module addReads(Module other) {
358         Objects.requireNonNull(other);
359         if (this.isNamed()) {
360             Module caller = getCallerModule(Reflection.getCallerClass());
361             if (caller != this) {
362                 throw new IllegalCallerException(caller + " != " + this);
363             }
364             implAddReads(other, true);
365         }
366         return this;
367     }
368 
369     /**
370      * Updates this module to read another module.
371      *
372      * @apiNote Used by the --add-reads command line option.
373      */
implAddReads(Module other)374     void implAddReads(Module other) {
375         implAddReads(other, true);
376     }
377 
378     /**
379      * Updates this module to read all unnamed modules.
380      *
381      * @apiNote Used by the --add-reads command line option.
382      */
implAddReadsAllUnnamed()383     void implAddReadsAllUnnamed() {
384         implAddReads(Module.ALL_UNNAMED_MODULE, true);
385     }
386 
387     /**
388      * Updates this module to read another module without notifying the VM.
389      *
390      * @apiNote This method is for VM white-box testing.
391      */
implAddReadsNoSync(Module other)392     void implAddReadsNoSync(Module other) {
393         implAddReads(other, false);
394     }
395 
396     /**
397      * Makes the given {@code Module} readable to this module.
398      *
399      * If {@code syncVM} is {@code true} then the VM is notified.
400      */
implAddReads(Module other, boolean syncVM)401     private void implAddReads(Module other, boolean syncVM) {
402         Objects.requireNonNull(other);
403         if (!canRead(other)) {
404             // update VM first, just in case it fails
405             if (syncVM) {
406                 if (other == ALL_UNNAMED_MODULE) {
407                     addReads0(this, null);
408                 } else {
409                     addReads0(this, other);
410                 }
411             }
412 
413             // add reflective read
414             ReflectionData.reads.putIfAbsent(this, other, Boolean.TRUE);
415         }
416     }
417 
418 
419     // -- exported and open packages --
420 
421     // the packages are open to other modules, can be null
422     // if the value contains EVERYONE_MODULE then the package is open to all
423     private volatile Map<String, Set<Module>> openPackages;
424 
425     // the packages that are exported, can be null
426     // if the value contains EVERYONE_MODULE then the package is exported to all
427     private volatile Map<String, Set<Module>> exportedPackages;
428 
429     /**
430      * Returns {@code true} if this module exports the given package to at
431      * least the given module.
432      *
433      * <p> This method returns {@code true} if invoked to test if a package in
434      * this module is exported to itself. It always returns {@code true} when
435      * invoked on an unnamed module. A package that is {@link #isOpen open} to
436      * the given module is considered exported to that module at run-time and
437      * so this method returns {@code true} if the package is open to the given
438      * module. </p>
439      *
440      * <p> This method does not check if the given module reads this module. </p>
441      *
442      * @param  pn
443      *         The package name
444      * @param  other
445      *         The other module
446      *
447      * @return {@code true} if this module exports the package to at least the
448      *         given module
449      *
450      * @see ModuleDescriptor#exports()
451      * @see #addExports(String,Module)
452      */
isExported(String pn, Module other)453     public boolean isExported(String pn, Module other) {
454         Objects.requireNonNull(pn);
455         Objects.requireNonNull(other);
456         return implIsExportedOrOpen(pn, other, /*open*/false);
457     }
458 
459     /**
460      * Returns {@code true} if this module has <em>opened</em> a package to at
461      * least the given module.
462      *
463      * <p> This method returns {@code true} if invoked to test if a package in
464      * this module is open to itself. It returns {@code true} when invoked on an
465      * {@link ModuleDescriptor#isOpen open} module with a package in the module.
466      * It always returns {@code true} when invoked on an unnamed module. </p>
467      *
468      * <p> This method does not check if the given module reads this module. </p>
469      *
470      * @param  pn
471      *         The package name
472      * @param  other
473      *         The other module
474      *
475      * @return {@code true} if this module has <em>opened</em> the package
476      *         to at least the given module
477      *
478      * @see ModuleDescriptor#opens()
479      * @see #addOpens(String,Module)
480      * @see java.lang.reflect.AccessibleObject#setAccessible(boolean)
481      * @see java.lang.invoke.MethodHandles#privateLookupIn
482      */
isOpen(String pn, Module other)483     public boolean isOpen(String pn, Module other) {
484         Objects.requireNonNull(pn);
485         Objects.requireNonNull(other);
486         return implIsExportedOrOpen(pn, other, /*open*/true);
487     }
488 
489     /**
490      * Returns {@code true} if this module exports the given package
491      * unconditionally.
492      *
493      * <p> This method always returns {@code true} when invoked on an unnamed
494      * module. A package that is {@link #isOpen(String) opened} unconditionally
495      * is considered exported unconditionally at run-time and so this method
496      * returns {@code true} if the package is opened unconditionally. </p>
497      *
498      * <p> This method does not check if the given module reads this module. </p>
499      *
500      * @param  pn
501      *         The package name
502      *
503      * @return {@code true} if this module exports the package unconditionally
504      *
505      * @see ModuleDescriptor#exports()
506      */
isExported(String pn)507     public boolean isExported(String pn) {
508         Objects.requireNonNull(pn);
509         return implIsExportedOrOpen(pn, EVERYONE_MODULE, /*open*/false);
510     }
511 
512     /**
513      * Returns {@code true} if this module has <em>opened</em> a package
514      * unconditionally.
515      *
516      * <p> This method always returns {@code true} when invoked on an unnamed
517      * module. Additionally, it always returns {@code true} when invoked on an
518      * {@link ModuleDescriptor#isOpen open} module with a package in the
519      * module. </p>
520      *
521      * <p> This method does not check if the given module reads this module. </p>
522      *
523      * @param  pn
524      *         The package name
525      *
526      * @return {@code true} if this module has <em>opened</em> the package
527      *         unconditionally
528      *
529      * @see ModuleDescriptor#opens()
530      */
isOpen(String pn)531     public boolean isOpen(String pn) {
532         Objects.requireNonNull(pn);
533         return implIsExportedOrOpen(pn, EVERYONE_MODULE, /*open*/true);
534     }
535 
536 
537     /**
538      * Returns {@code true} if this module exports or opens the given package
539      * to the given module. If the other module is {@code EVERYONE_MODULE} then
540      * this method tests if the package is exported or opened unconditionally.
541      */
implIsExportedOrOpen(String pn, Module other, boolean open)542     private boolean implIsExportedOrOpen(String pn, Module other, boolean open) {
543         // all packages in unnamed modules are open
544         if (!isNamed())
545             return true;
546 
547         // all packages are exported/open to self
548         if (other == this && descriptor.packages().contains(pn))
549             return true;
550 
551         // all packages in open and automatic modules are open
552         if (descriptor.isOpen() || descriptor.isAutomatic())
553             return descriptor.packages().contains(pn);
554 
555         // exported/opened via module declaration/descriptor
556         if (isStaticallyExportedOrOpen(pn, other, open))
557             return true;
558 
559         // exported via addExports/addOpens
560         if (isReflectivelyExportedOrOpen(pn, other, open))
561             return true;
562 
563         // not exported or open to other
564         return false;
565     }
566 
567     /**
568      * Returns {@code true} if this module exports or opens a package to
569      * the given module via its module declaration or CLI options.
570      */
isStaticallyExportedOrOpen(String pn, Module other, boolean open)571     private boolean isStaticallyExportedOrOpen(String pn, Module other, boolean open) {
572         // test if package is open to everyone or <other>
573         Map<String, Set<Module>> openPackages = this.openPackages;
574         if (openPackages != null && allows(openPackages.get(pn), other)) {
575             return true;
576         }
577 
578         if (!open) {
579             // test package is exported to everyone or <other>
580             Map<String, Set<Module>> exportedPackages = this.exportedPackages;
581             if (exportedPackages != null && allows(exportedPackages.get(pn), other)) {
582                 return true;
583             }
584         }
585 
586         return false;
587     }
588 
589     /**
590      * Returns {@code true} if targets is non-null and contains EVERYONE_MODULE
591      * or the given module. Also returns true if the given module is an unnamed
592      * module and targets contains ALL_UNNAMED_MODULE.
593      */
allows(Set<Module> targets, Module module)594     private boolean allows(Set<Module> targets, Module module) {
595        if (targets != null) {
596            if (targets.contains(EVERYONE_MODULE))
597                return true;
598            if (module != EVERYONE_MODULE) {
599                if (targets.contains(module))
600                    return true;
601                if (!module.isNamed() && targets.contains(ALL_UNNAMED_MODULE))
602                    return true;
603            }
604         }
605         return false;
606     }
607 
608     /**
609      * Returns {@code true} if this module reflectively exports or opens the
610      * given package to the given module.
611      */
isReflectivelyExportedOrOpen(String pn, Module other, boolean open)612     private boolean isReflectivelyExportedOrOpen(String pn, Module other, boolean open) {
613         // exported or open to all modules
614         Map<String, Boolean> exports = ReflectionData.exports.get(this, EVERYONE_MODULE);
615         if (exports != null) {
616             Boolean b = exports.get(pn);
617             if (b != null) {
618                 boolean isOpen = b.booleanValue();
619                 if (!open || isOpen) return true;
620             }
621         }
622 
623         if (other != EVERYONE_MODULE) {
624 
625             // exported or open to other
626             exports = ReflectionData.exports.get(this, other);
627             if (exports != null) {
628                 Boolean b = exports.get(pn);
629                 if (b != null) {
630                     boolean isOpen = b.booleanValue();
631                     if (!open || isOpen) return true;
632                 }
633             }
634 
635             // other is an unnamed module && exported or open to all unnamed
636             if (!other.isNamed()) {
637                 exports = ReflectionData.exports.get(this, ALL_UNNAMED_MODULE);
638                 if (exports != null) {
639                     Boolean b = exports.get(pn);
640                     if (b != null) {
641                         boolean isOpen = b.booleanValue();
642                         if (!open || isOpen) return true;
643                     }
644                 }
645             }
646 
647         }
648 
649         return false;
650     }
651 
652     /**
653      * Returns {@code true} if this module reflectively exports the
654      * given package to the given module.
655      */
isReflectivelyExported(String pn, Module other)656     boolean isReflectivelyExported(String pn, Module other) {
657         return isReflectivelyExportedOrOpen(pn, other, false);
658     }
659 
660     /**
661      * Returns {@code true} if this module reflectively opens the
662      * given package to the given module.
663      */
isReflectivelyOpened(String pn, Module other)664     boolean isReflectivelyOpened(String pn, Module other) {
665         return isReflectivelyExportedOrOpen(pn, other, true);
666     }
667 
668 
669     /**
670      * If the caller's module is this module then update this module to export
671      * the given package to the given module.
672      *
673      * <p> This method has no effect if the package is already exported (or
674      * <em>open</em>) to the given module. </p>
675      *
676      * @apiNote As specified in section 5.4.3 of the <cite>The Java&trade;
677      * Virtual Machine Specification </cite>, if an attempt to resolve a
678      * symbolic reference fails because of a linkage error, then subsequent
679      * attempts to resolve the reference always fail with the same error that
680      * was thrown as a result of the initial resolution attempt.
681      *
682      * @param  pn
683      *         The package name
684      * @param  other
685      *         The module
686      *
687      * @return this module
688      *
689      * @throws IllegalArgumentException
690      *         If {@code pn} is {@code null}, or this is a named module and the
691      *         package {@code pn} is not a package in this module
692      * @throws IllegalCallerException
693      *         If this is a named module and the caller's module is not this
694      *         module
695      *
696      * @jvms 5.4.3 Resolution
697      * @see #isExported(String,Module)
698      */
699     @CallerSensitive
addExports(String pn, Module other)700     public Module addExports(String pn, Module other) {
701         if (pn == null)
702             throw new IllegalArgumentException("package is null");
703         Objects.requireNonNull(other);
704 
705         if (isNamed()) {
706             Module caller = getCallerModule(Reflection.getCallerClass());
707             if (caller != this) {
708                 throw new IllegalCallerException(caller + " != " + this);
709             }
710             implAddExportsOrOpens(pn, other, /*open*/false, /*syncVM*/true);
711         }
712 
713         return this;
714     }
715 
716     /**
717      * If this module has <em>opened</em> a package to at least the caller
718      * module then update this module to open the package to the given module.
719      * Opening a package with this method allows all types in the package,
720      * and all their members, not just public types and their public members,
721      * to be reflected on by the given module when using APIs that support
722      * private access or a way to bypass or suppress default Java language
723      * access control checks.
724      *
725      * <p> This method has no effect if the package is already <em>open</em>
726      * to the given module. </p>
727      *
728      * @apiNote This method can be used for cases where a <em>consumer
729      * module</em> uses a qualified opens to open a package to an <em>API
730      * module</em> but where the reflective access to the members of classes in
731      * the consumer module is delegated to code in another module. Code in the
732      * API module can use this method to open the package in the consumer module
733      * to the other module.
734      *
735      * @param  pn
736      *         The package name
737      * @param  other
738      *         The module
739      *
740      * @return this module
741      *
742      * @throws IllegalArgumentException
743      *         If {@code pn} is {@code null}, or this is a named module and the
744      *         package {@code pn} is not a package in this module
745      * @throws IllegalCallerException
746      *         If this is a named module and this module has not opened the
747      *         package to at least the caller's module
748      *
749      * @see #isOpen(String,Module)
750      * @see java.lang.reflect.AccessibleObject#setAccessible(boolean)
751      * @see java.lang.invoke.MethodHandles#privateLookupIn
752      */
753     @CallerSensitive
addOpens(String pn, Module other)754     public Module addOpens(String pn, Module other) {
755         if (pn == null)
756             throw new IllegalArgumentException("package is null");
757         Objects.requireNonNull(other);
758 
759         if (isNamed()) {
760             Module caller = getCallerModule(Reflection.getCallerClass());
761             if (caller != this && (caller == null || !isOpen(pn, caller)))
762                 throw new IllegalCallerException(pn + " is not open to " + caller);
763             implAddExportsOrOpens(pn, other, /*open*/true, /*syncVM*/true);
764         }
765 
766         return this;
767     }
768 
769 
770     /**
771      * Updates this module to export a package unconditionally.
772      *
773      * @apiNote This method is for JDK tests only.
774      */
implAddExports(String pn)775     void implAddExports(String pn) {
776         implAddExportsOrOpens(pn, Module.EVERYONE_MODULE, false, true);
777     }
778 
779     /**
780      * Updates this module to export a package to another module.
781      *
782      * @apiNote Used by Instrumentation::redefineModule and --add-exports
783      */
implAddExports(String pn, Module other)784     void implAddExports(String pn, Module other) {
785         implAddExportsOrOpens(pn, other, false, true);
786     }
787 
788     /**
789      * Updates this module to export a package to all unnamed modules.
790      *
791      * @apiNote Used by the --add-exports command line option.
792      */
implAddExportsToAllUnnamed(String pn)793     void implAddExportsToAllUnnamed(String pn) {
794         implAddExportsOrOpens(pn, Module.ALL_UNNAMED_MODULE, false, true);
795     }
796 
797     /**
798      * Updates this export to export a package unconditionally without
799      * notifying the VM.
800      *
801      * @apiNote This method is for VM white-box testing.
802      */
implAddExportsNoSync(String pn)803     void implAddExportsNoSync(String pn) {
804         implAddExportsOrOpens(pn.replace('/', '.'), Module.EVERYONE_MODULE, false, false);
805     }
806 
807     /**
808      * Updates a module to export a package to another module without
809      * notifying the VM.
810      *
811      * @apiNote This method is for VM white-box testing.
812      */
implAddExportsNoSync(String pn, Module other)813     void implAddExportsNoSync(String pn, Module other) {
814         implAddExportsOrOpens(pn.replace('/', '.'), other, false, false);
815     }
816 
817     /**
818      * Updates this module to open a package unconditionally.
819      *
820      * @apiNote This method is for JDK tests only.
821      */
implAddOpens(String pn)822     void implAddOpens(String pn) {
823         implAddExportsOrOpens(pn, Module.EVERYONE_MODULE, true, true);
824     }
825 
826     /**
827      * Updates this module to open a package to another module.
828      *
829      * @apiNote Used by Instrumentation::redefineModule and --add-opens
830      */
implAddOpens(String pn, Module other)831     void implAddOpens(String pn, Module other) {
832         implAddExportsOrOpens(pn, other, true, true);
833     }
834 
835     /**
836      * Updates this module to open a package to all unnamed modules.
837      *
838      * @apiNote Used by the --add-opens command line option.
839      */
implAddOpensToAllUnnamed(String pn)840     void implAddOpensToAllUnnamed(String pn) {
841         implAddExportsOrOpens(pn, Module.ALL_UNNAMED_MODULE, true, true);
842     }
843 
844     /**
845      * Updates a module to export or open a module to another module.
846      *
847      * If {@code syncVM} is {@code true} then the VM is notified.
848      */
implAddExportsOrOpens(String pn, Module other, boolean open, boolean syncVM)849     private void implAddExportsOrOpens(String pn,
850                                        Module other,
851                                        boolean open,
852                                        boolean syncVM) {
853         Objects.requireNonNull(other);
854         Objects.requireNonNull(pn);
855 
856         // all packages are open in unnamed, open, and automatic modules
857         if (!isNamed() || descriptor.isOpen() || descriptor.isAutomatic())
858             return;
859 
860         // check if the package is already exported/open to other
861         if (implIsExportedOrOpen(pn, other, open)) {
862 
863             // if the package is exported/open for illegal access then we need
864             // to record that it has also been exported/opened reflectively so
865             // that the IllegalAccessLogger doesn't emit a warning.
866             boolean needToAdd = false;
867             if (!other.isNamed()) {
868                 IllegalAccessLogger l = IllegalAccessLogger.illegalAccessLogger();
869                 if (l != null) {
870                     if (open) {
871                         needToAdd = l.isOpenForIllegalAccess(this, pn);
872                     } else {
873                         needToAdd = l.isExportedForIllegalAccess(this, pn);
874                     }
875                 }
876             }
877             if (!needToAdd) {
878                 // nothing to do
879                 return;
880             }
881         }
882 
883         // can only export a package in the module
884         if (!descriptor.packages().contains(pn)) {
885             throw new IllegalArgumentException("package " + pn
886                                                + " not in contents");
887         }
888 
889         // update VM first, just in case it fails
890         if (syncVM) {
891             if (other == EVERYONE_MODULE) {
892                 addExportsToAll0(this, pn);
893             } else if (other == ALL_UNNAMED_MODULE) {
894                 addExportsToAllUnnamed0(this, pn);
895             } else {
896                 addExports0(this, pn, other);
897             }
898         }
899 
900         // add package name to exports if absent
901         Map<String, Boolean> map = ReflectionData.exports
902             .computeIfAbsent(this, other,
903                              (m1, m2) -> new ConcurrentHashMap<>());
904         if (open) {
905             map.put(pn, Boolean.TRUE);  // may need to promote from FALSE to TRUE
906         } else {
907             map.putIfAbsent(pn, Boolean.FALSE);
908         }
909     }
910 
911     /**
912      * Updates a module to open all packages returned by the given iterator to
913      * all unnamed modules.
914      *
915      * @apiNote Used during startup to open packages for illegal access.
916      */
implAddOpensToAllUnnamed(Iterator<String> iterator)917     void implAddOpensToAllUnnamed(Iterator<String> iterator) {
918         if (jdk.internal.misc.VM.isModuleSystemInited()) {
919             throw new IllegalStateException("Module system already initialized");
920         }
921 
922         // replace this module's openPackages map with a new map that opens
923         // the packages to all unnamed modules.
924         Map<String, Set<Module>> openPackages = this.openPackages;
925         if (openPackages == null) {
926             openPackages = new HashMap<>();
927         } else {
928             openPackages = new HashMap<>(openPackages);
929         }
930         while (iterator.hasNext()) {
931             String pn = iterator.next();
932             Set<Module> prev = openPackages.putIfAbsent(pn, ALL_UNNAMED_MODULE_SET);
933             if (prev != null) {
934                 prev.add(ALL_UNNAMED_MODULE);
935             }
936 
937             // update VM to export the package
938             addExportsToAllUnnamed0(this, pn);
939         }
940         this.openPackages = openPackages;
941     }
942 
943 
944     // -- services --
945 
946     /**
947      * If the caller's module is this module then update this module to add a
948      * service dependence on the given service type. This method is intended
949      * for use by frameworks that invoke {@link java.util.ServiceLoader
950      * ServiceLoader} on behalf of other modules or where the framework is
951      * passed a reference to the service type by other code. This method is
952      * a no-op when invoked on an unnamed module or an automatic module.
953      *
954      * <p> This method does not cause {@link Configuration#resolveAndBind
955      * resolveAndBind} to be re-run. </p>
956      *
957      * @param  service
958      *         The service type
959      *
960      * @return this module
961      *
962      * @throws IllegalCallerException
963      *         If this is a named module and the caller's module is not this
964      *         module
965      *
966      * @see #canUse(Class)
967      * @see ModuleDescriptor#uses()
968      */
969     @CallerSensitive
addUses(Class<?> service)970     public Module addUses(Class<?> service) {
971         Objects.requireNonNull(service);
972 
973         if (isNamed() && !descriptor.isAutomatic()) {
974             Module caller = getCallerModule(Reflection.getCallerClass());
975             if (caller != this) {
976                 throw new IllegalCallerException(caller + " != " + this);
977             }
978             implAddUses(service);
979         }
980 
981         return this;
982     }
983 
984     /**
985      * Update this module to add a service dependence on the given service
986      * type.
987      */
implAddUses(Class<?> service)988     void implAddUses(Class<?> service) {
989         if (!canUse(service)) {
990             ReflectionData.uses.putIfAbsent(this, service, Boolean.TRUE);
991         }
992     }
993 
994 
995     /**
996      * Indicates if this module has a service dependence on the given service
997      * type. This method always returns {@code true} when invoked on an unnamed
998      * module or an automatic module.
999      *
1000      * @param  service
1001      *         The service type
1002      *
1003      * @return {@code true} if this module uses service type {@code st}
1004      *
1005      * @see #addUses(Class)
1006      */
canUse(Class<?> service)1007     public boolean canUse(Class<?> service) {
1008         Objects.requireNonNull(service);
1009 
1010         if (!isNamed())
1011             return true;
1012 
1013         if (descriptor.isAutomatic())
1014             return true;
1015 
1016         // uses was declared
1017         if (descriptor.uses().contains(service.getName()))
1018             return true;
1019 
1020         // uses added via addUses
1021         return ReflectionData.uses.containsKeyPair(this, service);
1022     }
1023 
1024 
1025 
1026     // -- packages --
1027 
1028     /**
1029      * Returns the set of package names for the packages in this module.
1030      *
1031      * <p> For named modules, the returned set contains an element for each
1032      * package in the module. </p>
1033      *
1034      * <p> For unnamed modules, this method is the equivalent to invoking the
1035      * {@link ClassLoader#getDefinedPackages() getDefinedPackages} method of
1036      * this module's class loader and returning the set of package names. </p>
1037      *
1038      * @return the set of the package names of the packages in this module
1039      */
getPackages()1040     public Set<String> getPackages() {
1041         if (isNamed()) {
1042             return descriptor.packages();
1043         } else {
1044             // unnamed module
1045             Stream<Package> packages;
1046             if (loader == null) {
1047                 packages = BootLoader.packages();
1048             } else {
1049                 packages = loader.packages();
1050             }
1051             return packages.map(Package::getName).collect(Collectors.toSet());
1052         }
1053     }
1054 
1055 
1056     // -- creating Module objects --
1057 
1058     /**
1059      * Defines all module in a configuration to the runtime.
1060      *
1061      * @return a map of module name to runtime {@code Module}
1062      *
1063      * @throws IllegalArgumentException
1064      *         If the function maps a module to the null or platform class loader
1065      * @throws IllegalStateException
1066      *         If the module cannot be defined to the VM or its packages overlap
1067      *         with another module mapped to the same class loader
1068      */
defineModules(Configuration cf, Function<String, ClassLoader> clf, ModuleLayer layer)1069     static Map<String, Module> defineModules(Configuration cf,
1070                                              Function<String, ClassLoader> clf,
1071                                              ModuleLayer layer)
1072     {
1073         boolean isBootLayer = (ModuleLayer.boot() == null);
1074 
1075         int cap = (int)(cf.modules().size() / 0.75f + 1.0f);
1076         Map<String, Module> nameToModule = new HashMap<>(cap);
1077         Map<String, ClassLoader> nameToLoader = new HashMap<>(cap);
1078 
1079         Set<ClassLoader> loaders = new HashSet<>();
1080         boolean hasPlatformModules = false;
1081 
1082         // map each module to a class loader
1083         for (ResolvedModule resolvedModule : cf.modules()) {
1084             String name = resolvedModule.name();
1085             ClassLoader loader = clf.apply(name);
1086             nameToLoader.put(name, loader);
1087             if (loader == null || loader == ClassLoaders.platformClassLoader()) {
1088                 if (!(clf instanceof ModuleLoaderMap.Mapper)) {
1089                     throw new IllegalArgumentException("loader can't be 'null'"
1090                             + " or the platform class loader");
1091                 }
1092                 hasPlatformModules = true;
1093             } else {
1094                 loaders.add(loader);
1095             }
1096         }
1097 
1098         // define each module in the configuration to the VM
1099         for (ResolvedModule resolvedModule : cf.modules()) {
1100             ModuleReference mref = resolvedModule.reference();
1101             ModuleDescriptor descriptor = mref.descriptor();
1102             String name = descriptor.name();
1103             ClassLoader loader = nameToLoader.get(name);
1104             Module m;
1105             if (loader == null && name.equals("java.base")) {
1106                 // java.base is already defined to the VM
1107                 m = Object.class.getModule();
1108             } else {
1109                 URI uri = mref.location().orElse(null);
1110                 m = new Module(layer, loader, descriptor, uri);
1111             }
1112             nameToModule.put(name, m);
1113         }
1114 
1115         // setup readability and exports/opens
1116         for (ResolvedModule resolvedModule : cf.modules()) {
1117             ModuleReference mref = resolvedModule.reference();
1118             ModuleDescriptor descriptor = mref.descriptor();
1119 
1120             String mn = descriptor.name();
1121             Module m = nameToModule.get(mn);
1122             assert m != null;
1123 
1124             // reads
1125             Set<Module> reads = new HashSet<>();
1126 
1127             // name -> source Module when in parent layer
1128             Map<String, Module> nameToSource = Map.of();
1129 
1130             for (ResolvedModule other : resolvedModule.reads()) {
1131                 Module m2 = null;
1132                 if (other.configuration() == cf) {
1133                     // this configuration
1134                     m2 = nameToModule.get(other.name());
1135                     assert m2 != null;
1136                 } else {
1137                     // parent layer
1138                     for (ModuleLayer parent: layer.parents()) {
1139                         m2 = findModule(parent, other);
1140                         if (m2 != null)
1141                             break;
1142                     }
1143                     assert m2 != null;
1144                     if (nameToSource.isEmpty())
1145                         nameToSource = new HashMap<>();
1146                     nameToSource.put(other.name(), m2);
1147                 }
1148                 reads.add(m2);
1149 
1150                 // update VM view
1151                 addReads0(m, m2);
1152             }
1153             m.reads = reads;
1154 
1155             // automatic modules read all unnamed modules
1156             if (descriptor.isAutomatic()) {
1157                 m.implAddReads(ALL_UNNAMED_MODULE, true);
1158             }
1159 
1160             // exports and opens, skipped for open and automatic
1161             if (!descriptor.isOpen() && !descriptor.isAutomatic()) {
1162                 if (isBootLayer && descriptor.opens().isEmpty()) {
1163                     // no open packages, no qualified exports to modules in parent layers
1164                     initExports(m, nameToModule);
1165                 } else {
1166                     initExportsAndOpens(m, nameToSource, nameToModule, layer.parents());
1167                 }
1168             }
1169         }
1170 
1171         // if there are modules defined to the boot or platform class loaders
1172         // then register the modules in the class loader's services catalog
1173         if (hasPlatformModules) {
1174             ClassLoader pcl = ClassLoaders.platformClassLoader();
1175             ServicesCatalog bootCatalog = BootLoader.getServicesCatalog();
1176             ServicesCatalog pclCatalog = ServicesCatalog.getServicesCatalog(pcl);
1177             for (ResolvedModule resolvedModule : cf.modules()) {
1178                 ModuleReference mref = resolvedModule.reference();
1179                 ModuleDescriptor descriptor = mref.descriptor();
1180                 if (!descriptor.provides().isEmpty()) {
1181                     String name = descriptor.name();
1182                     Module m = nameToModule.get(name);
1183                     ClassLoader loader = nameToLoader.get(name);
1184                     if (loader == null) {
1185                         bootCatalog.register(m);
1186                     } else if (loader == pcl) {
1187                         pclCatalog.register(m);
1188                     }
1189                 }
1190             }
1191         }
1192 
1193         // record that there is a layer with modules defined to the class loader
1194         for (ClassLoader loader : loaders) {
1195             layer.bindToLoader(loader);
1196         }
1197 
1198         return nameToModule;
1199     }
1200 
1201     /**
1202      * Find the runtime Module corresponding to the given ResolvedModule
1203      * in the given parent layer (or its parents).
1204      */
findModule(ModuleLayer parent, ResolvedModule resolvedModule)1205     private static Module findModule(ModuleLayer parent,
1206                                      ResolvedModule resolvedModule) {
1207         Configuration cf = resolvedModule.configuration();
1208         String dn = resolvedModule.name();
1209         return parent.layers()
1210                 .filter(l -> l.configuration() == cf)
1211                 .findAny()
1212                 .map(layer -> {
1213                     Optional<Module> om = layer.findModule(dn);
1214                     assert om.isPresent() : dn + " not found in layer";
1215                     Module m = om.get();
1216                     assert m.getLayer() == layer : m + " not in expected layer";
1217                     return m;
1218                 })
1219                 .orElse(null);
1220     }
1221 
1222     /**
1223      * Initialize/setup a module's exports.
1224      *
1225      * @param m the module
1226      * @param nameToModule map of module name to Module (for qualified exports)
1227      */
initExports(Module m, Map<String, Module> nameToModule)1228     private static void initExports(Module m, Map<String, Module> nameToModule) {
1229         Map<String, Set<Module>> exportedPackages = new HashMap<>();
1230 
1231         for (Exports exports : m.getDescriptor().exports()) {
1232             String source = exports.source();
1233             if (exports.isQualified()) {
1234                 // qualified exports
1235                 Set<Module> targets = new HashSet<>();
1236                 for (String target : exports.targets()) {
1237                     Module m2 = nameToModule.get(target);
1238                     if (m2 != null) {
1239                         addExports0(m, source, m2);
1240                         targets.add(m2);
1241                     }
1242                 }
1243                 if (!targets.isEmpty()) {
1244                     exportedPackages.put(source, targets);
1245                 }
1246             } else {
1247                 // unqualified exports
1248                 addExportsToAll0(m, source);
1249                 exportedPackages.put(source, EVERYONE_SET);
1250             }
1251         }
1252 
1253         if (!exportedPackages.isEmpty())
1254             m.exportedPackages = exportedPackages;
1255     }
1256 
1257     /**
1258      * Initialize/setup a module's exports.
1259      *
1260      * @param m the module
1261      * @param nameToSource map of module name to Module for modules that m reads
1262      * @param nameToModule map of module name to Module for modules in the layer
1263      *                     under construction
1264      * @param parents the parent layers
1265      */
initExportsAndOpens(Module m, Map<String, Module> nameToSource, Map<String, Module> nameToModule, List<ModuleLayer> parents)1266     private static void initExportsAndOpens(Module m,
1267                                             Map<String, Module> nameToSource,
1268                                             Map<String, Module> nameToModule,
1269                                             List<ModuleLayer> parents) {
1270         ModuleDescriptor descriptor = m.getDescriptor();
1271         Map<String, Set<Module>> openPackages = new HashMap<>();
1272         Map<String, Set<Module>> exportedPackages = new HashMap<>();
1273 
1274         // process the open packages first
1275         for (Opens opens : descriptor.opens()) {
1276             String source = opens.source();
1277 
1278             if (opens.isQualified()) {
1279                 // qualified opens
1280                 Set<Module> targets = new HashSet<>();
1281                 for (String target : opens.targets()) {
1282                     Module m2 = findModule(target, nameToSource, nameToModule, parents);
1283                     if (m2 != null) {
1284                         addExports0(m, source, m2);
1285                         targets.add(m2);
1286                     }
1287                 }
1288                 if (!targets.isEmpty()) {
1289                     openPackages.put(source, targets);
1290                 }
1291             } else {
1292                 // unqualified opens
1293                 addExportsToAll0(m, source);
1294                 openPackages.put(source, EVERYONE_SET);
1295             }
1296         }
1297 
1298         // next the exports, skipping exports when the package is open
1299         for (Exports exports : descriptor.exports()) {
1300             String source = exports.source();
1301 
1302             // skip export if package is already open to everyone
1303             Set<Module> openToTargets = openPackages.get(source);
1304             if (openToTargets != null && openToTargets.contains(EVERYONE_MODULE))
1305                 continue;
1306 
1307             if (exports.isQualified()) {
1308                 // qualified exports
1309                 Set<Module> targets = new HashSet<>();
1310                 for (String target : exports.targets()) {
1311                     Module m2 = findModule(target, nameToSource, nameToModule, parents);
1312                     if (m2 != null) {
1313                         // skip qualified export if already open to m2
1314                         if (openToTargets == null || !openToTargets.contains(m2)) {
1315                             addExports0(m, source, m2);
1316                             targets.add(m2);
1317                         }
1318                     }
1319                 }
1320                 if (!targets.isEmpty()) {
1321                     exportedPackages.put(source, targets);
1322                 }
1323             } else {
1324                 // unqualified exports
1325                 addExportsToAll0(m, source);
1326                 exportedPackages.put(source, EVERYONE_SET);
1327             }
1328         }
1329 
1330         if (!openPackages.isEmpty())
1331             m.openPackages = openPackages;
1332         if (!exportedPackages.isEmpty())
1333             m.exportedPackages = exportedPackages;
1334     }
1335 
1336     /**
1337      * Find the runtime Module with the given name. The module name is the
1338      * name of a target module in a qualified exports or opens directive.
1339      *
1340      * @param target The target module to find
1341      * @param nameToSource The modules in parent layers that are read
1342      * @param nameToModule The modules in the layer under construction
1343      * @param parents The parent layers
1344      */
findModule(String target, Map<String, Module> nameToSource, Map<String, Module> nameToModule, List<ModuleLayer> parents)1345     private static Module findModule(String target,
1346                                      Map<String, Module> nameToSource,
1347                                      Map<String, Module> nameToModule,
1348                                      List<ModuleLayer> parents) {
1349         Module m = nameToSource.get(target);
1350         if (m == null) {
1351             m = nameToModule.get(target);
1352             if (m == null) {
1353                 for (ModuleLayer parent : parents) {
1354                     m = parent.findModule(target).orElse(null);
1355                     if (m != null) break;
1356                 }
1357             }
1358         }
1359         return m;
1360     }
1361 
1362 
1363     // -- annotations --
1364 
1365     /**
1366      * {@inheritDoc}
1367      * This method returns {@code null} when invoked on an unnamed module.
1368      */
1369     @Override
getAnnotation(Class<T> annotationClass)1370     public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
1371         return moduleInfoClass().getDeclaredAnnotation(annotationClass);
1372     }
1373 
1374     /**
1375      * {@inheritDoc}
1376      * This method returns an empty array when invoked on an unnamed module.
1377      */
1378     @Override
getAnnotations()1379     public Annotation[] getAnnotations() {
1380         return moduleInfoClass().getAnnotations();
1381     }
1382 
1383     /**
1384      * {@inheritDoc}
1385      * This method returns an empty array when invoked on an unnamed module.
1386      */
1387     @Override
getDeclaredAnnotations()1388     public Annotation[] getDeclaredAnnotations() {
1389         return moduleInfoClass().getDeclaredAnnotations();
1390     }
1391 
1392     // cached class file with annotations
1393     private volatile Class<?> moduleInfoClass;
1394 
moduleInfoClass()1395     private Class<?> moduleInfoClass() {
1396         Class<?> clazz = this.moduleInfoClass;
1397         if (clazz != null)
1398             return clazz;
1399 
1400         synchronized (this) {
1401             clazz = this.moduleInfoClass;
1402             if (clazz == null) {
1403                 if (isNamed()) {
1404                     PrivilegedAction<Class<?>> pa = this::loadModuleInfoClass;
1405                     clazz = AccessController.doPrivileged(pa);
1406                 }
1407                 if (clazz == null) {
1408                     class DummyModuleInfo { }
1409                     clazz = DummyModuleInfo.class;
1410                 }
1411                 this.moduleInfoClass = clazz;
1412             }
1413             return clazz;
1414         }
1415     }
1416 
loadModuleInfoClass()1417     private Class<?> loadModuleInfoClass() {
1418         Class<?> clazz = null;
1419         try (InputStream in = getResourceAsStream("module-info.class")) {
1420             if (in != null)
1421                 clazz = loadModuleInfoClass(in);
1422         } catch (Exception ignore) { }
1423         return clazz;
1424     }
1425 
1426     /**
1427      * Loads module-info.class as a package-private interface in a class loader
1428      * that is a child of this module's class loader.
1429      */
loadModuleInfoClass(InputStream in)1430     private Class<?> loadModuleInfoClass(InputStream in) throws IOException {
1431         final String MODULE_INFO = "module-info";
1432 
1433         ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS
1434                                          + ClassWriter.COMPUTE_FRAMES);
1435 
1436         ClassVisitor cv = new ClassVisitor(Opcodes.ASM7, cw) {
1437             @Override
1438             public void visit(int version,
1439                               int access,
1440                               String name,
1441                               String signature,
1442                               String superName,
1443                               String[] interfaces) {
1444                 cw.visit(version,
1445                         Opcodes.ACC_INTERFACE
1446                             + Opcodes.ACC_ABSTRACT
1447                             + Opcodes.ACC_SYNTHETIC,
1448                         MODULE_INFO,
1449                         null,
1450                         "java/lang/Object",
1451                         null);
1452             }
1453             @Override
1454             public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
1455                 // keep annotations
1456                 return super.visitAnnotation(desc, visible);
1457             }
1458             @Override
1459             public void visitAttribute(Attribute attr) {
1460                 // drop non-annotation attributes
1461             }
1462             @Override
1463             public ModuleVisitor visitModule(String name, int flags, String version) {
1464                 // drop Module attribute
1465                 return null;
1466             }
1467         };
1468 
1469         ClassReader cr = new ClassReader(in);
1470         cr.accept(cv, 0);
1471         byte[] bytes = cw.toByteArray();
1472 
1473         ClassLoader cl = new ClassLoader(loader) {
1474             @Override
1475             protected Class<?> findClass(String cn)throws ClassNotFoundException {
1476                 if (cn.equals(MODULE_INFO)) {
1477                     return super.defineClass(cn, bytes, 0, bytes.length);
1478                 } else {
1479                     throw new ClassNotFoundException(cn);
1480                 }
1481             }
1482         };
1483 
1484         try {
1485             return cl.loadClass(MODULE_INFO);
1486         } catch (ClassNotFoundException e) {
1487             throw new InternalError(e);
1488         }
1489     }
1490 
1491 
1492     // -- misc --
1493 
1494 
1495     /**
1496      * Returns an input stream for reading a resource in this module.
1497      * The {@code name} parameter is a {@code '/'}-separated path name that
1498      * identifies the resource. As with {@link Class#getResourceAsStream
1499      * Class.getResourceAsStream}, this method delegates to the module's class
1500      * loader {@link ClassLoader#findResource(String,String)
1501      * findResource(String,String)} method, invoking it with the module name
1502      * (or {@code null} when the module is unnamed) and the name of the
1503      * resource. If the resource name has a leading slash then it is dropped
1504      * before delegation.
1505      *
1506      * <p> A resource in a named module may be <em>encapsulated</em> so that
1507      * it cannot be located by code in other modules. Whether a resource can be
1508      * located or not is determined as follows: </p>
1509      *
1510      * <ul>
1511      *     <li> If the resource name ends with  "{@code .class}" then it is not
1512      *     encapsulated. </li>
1513      *
1514      *     <li> A <em>package name</em> is derived from the resource name. If
1515      *     the package name is a {@linkplain #getPackages() package} in the
1516      *     module then the resource can only be located by the caller of this
1517      *     method when the package is {@linkplain #isOpen(String,Module) open}
1518      *     to at least the caller's module. If the resource is not in a
1519      *     package in the module then the resource is not encapsulated. </li>
1520      * </ul>
1521      *
1522      * <p> In the above, the <em>package name</em> for a resource is derived
1523      * from the subsequence of characters that precedes the last {@code '/'} in
1524      * the name and then replacing each {@code '/'} character in the subsequence
1525      * with {@code '.'}. A leading slash is ignored when deriving the package
1526      * name. As an example, the package name derived for a resource named
1527      * "{@code a/b/c/foo.properties}" is "{@code a.b.c}". A resource name
1528      * with the name "{@code META-INF/MANIFEST.MF}" is never encapsulated
1529      * because "{@code META-INF}" is not a legal package name. </p>
1530      *
1531      * <p> This method returns {@code null} if the resource is not in this
1532      * module, the resource is encapsulated and cannot be located by the caller,
1533      * or access to the resource is denied by the security manager. </p>
1534      *
1535      * @param  name
1536      *         The resource name
1537      *
1538      * @return An input stream for reading the resource or {@code null}
1539      *
1540      * @throws IOException
1541      *         If an I/O error occurs
1542      *
1543      * @see Class#getResourceAsStream(String)
1544      */
1545     @CallerSensitive
getResourceAsStream(String name)1546     public InputStream getResourceAsStream(String name) throws IOException {
1547         if (name.startsWith("/")) {
1548             name = name.substring(1);
1549         }
1550 
1551         if (isNamed() && Resources.canEncapsulate(name)) {
1552             Module caller = getCallerModule(Reflection.getCallerClass());
1553             if (caller != this && caller != Object.class.getModule()) {
1554                 String pn = Resources.toPackageName(name);
1555                 if (getPackages().contains(pn)) {
1556                     if (caller == null && !isOpen(pn)) {
1557                         // no caller, package not open
1558                         return null;
1559                     }
1560                     if (!isOpen(pn, caller)) {
1561                         // package not open to caller
1562                         return null;
1563                     }
1564                 }
1565             }
1566         }
1567 
1568         String mn = this.name;
1569 
1570         // special-case built-in class loaders to avoid URL connection
1571         if (loader == null) {
1572             return BootLoader.findResourceAsStream(mn, name);
1573         } else if (loader instanceof BuiltinClassLoader) {
1574             return ((BuiltinClassLoader) loader).findResourceAsStream(mn, name);
1575         }
1576 
1577         // locate resource in module
1578         URL url = loader.findResource(mn, name);
1579         if (url != null) {
1580             try {
1581                 return url.openStream();
1582             } catch (SecurityException e) { }
1583         }
1584 
1585         return null;
1586     }
1587 
1588     /**
1589      * Returns the string representation of this module. For a named module,
1590      * the representation is the string {@code "module"}, followed by a space,
1591      * and then the module name. For an unnamed module, the representation is
1592      * the string {@code "unnamed module"}, followed by a space, and then an
1593      * implementation specific string that identifies the unnamed module.
1594      *
1595      * @return The string representation of this module
1596      */
1597     @Override
toString()1598     public String toString() {
1599         if (isNamed()) {
1600             return "module " + name;
1601         } else {
1602             String id = Integer.toHexString(System.identityHashCode(this));
1603             return "unnamed module @" + id;
1604         }
1605     }
1606 
1607     /**
1608      * Returns the module that a given caller class is a member of. Returns
1609      * {@code null} if the caller is {@code null}.
1610      */
getCallerModule(Class<?> caller)1611     private Module getCallerModule(Class<?> caller) {
1612         return (caller != null) ? caller.getModule() : null;
1613     }
1614 
1615 
1616     // -- native methods --
1617 
1618     // JVM_DefineModule
defineModule0(Module module, boolean isOpen, String version, String location, String[] pns)1619     private static native void defineModule0(Module module,
1620                                              boolean isOpen,
1621                                              String version,
1622                                              String location,
1623                                              String[] pns);
1624 
1625     // JVM_AddReadsModule
addReads0(Module from, Module to)1626     private static native void addReads0(Module from, Module to);
1627 
1628     // JVM_AddModuleExports
addExports0(Module from, String pn, Module to)1629     private static native void addExports0(Module from, String pn, Module to);
1630 
1631     // JVM_AddModuleExportsToAll
addExportsToAll0(Module from, String pn)1632     private static native void addExportsToAll0(Module from, String pn);
1633 
1634     // JVM_AddModuleExportsToAllUnnamed
addExportsToAllUnnamed0(Module from, String pn)1635     private static native void addExportsToAllUnnamed0(Module from, String pn);
1636 }
1637