1 /*
   2  * Copyright (c) 2014, 2018, 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 jdk.internal.module;
  27 
  28 import java.io.File;
  29 import java.io.PrintStream;
  30 import java.lang.module.Configuration;
  31 import java.lang.module.ModuleDescriptor;
  32 import java.lang.module.ModuleFinder;
  33 import java.lang.module.ModuleReference;
  34 import java.lang.module.ResolvedModule;
  35 import java.net.URI;
  36 import java.nio.file.Path;
  37 import java.util.ArrayList;
  38 import java.util.Collections;
  39 import java.util.HashMap;
  40 import java.util.HashSet;
  41 import java.util.Iterator;
  42 import java.util.LinkedHashMap;
  43 import java.util.List;
  44 import java.util.Map;
  45 import java.util.NoSuchElementException;
  46 import java.util.Objects;
  47 import java.util.Optional;
  48 import java.util.Set;
  49 import java.util.function.Function;
  50 import java.util.stream.Collectors;
  51 
  52 import jdk.internal.loader.BootLoader;
  53 import jdk.internal.loader.BuiltinClassLoader;
  54 import jdk.internal.access.JavaLangAccess;
  55 import jdk.internal.access.JavaLangModuleAccess;
  56 import jdk.internal.access.SharedSecrets;
  57 import jdk.internal.perf.PerfCounter;
  58 
  59 /**
  60  * Initializes/boots the module system.
  61  *
  62  * The {@link #boot() boot} method is called early in the startup to initialize
  63  * the module system. In summary, the boot method creates a Configuration by
  64  * resolving a set of module names specified via the launcher (or equivalent)
  65  * -m and --add-modules options. The modules are located on a module path that
  66  * is constructed from the upgrade module path, system modules, and application
  67  * module path. The Configuration is instantiated as the boot layer with each
  68  * module in the configuration defined to a class loader.
  69  */
  70 
  71 public final class ModuleBootstrap {
  72     private ModuleBootstrap() { }
  73 
  74     private static final String JAVA_BASE = "java.base";
  75 
  76     // the token for "all default modules"
  77     private static final String ALL_DEFAULT = "ALL-DEFAULT";
  78 
  79     // the token for "all unnamed modules"
  80     private static final String ALL_UNNAMED = "ALL-UNNAMED";
  81 
  82     // the token for "all system modules"
  83     private static final String ALL_SYSTEM = "ALL-SYSTEM";
  84 
  85     // the token for "all modules on the module path"
  86     private static final String ALL_MODULE_PATH = "ALL-MODULE-PATH";
  87 
  88     // access to java.lang/module
  89     private static final JavaLangModuleAccess JLMA
  90         = SharedSecrets.getJavaLangModuleAccess();
  91 
  92     // The ModulePatcher for the initial configuration
  93     private static final ModulePatcher patcher = initModulePatcher();
  94 
  95     /**
  96      * Returns the ModulePatcher for the initial configuration.
  97      */
  98     public static ModulePatcher patcher() {
  99         return patcher;
 100     }
 101 
 102     // ModuleFinders for the initial configuration
 103     private static volatile ModuleFinder unlimitedFinder;
 104     private static volatile ModuleFinder limitedFinder;
 105 
 106     /**
 107      * Returns the ModuleFinder for the initial configuration before
 108      * observability is limited by the --limit-modules command line option.
 109      *
 110      * @apiNote Used to support locating modules {@code java.instrument} and
 111      * {@code jdk.management.agent} modules when they are loaded dynamically.
 112      */
 113     public static ModuleFinder unlimitedFinder() {
 114         ModuleFinder finder = unlimitedFinder;
 115         if (finder == null) {
 116             return ModuleFinder.ofSystem();
 117         } else {
 118             return finder;
 119         }
 120     }
 121 
 122     /**
 123      * Returns the ModuleFinder for the initial configuration.
 124      *
 125      * @apiNote Used to support "{@code java --list-modules}".
 126      */
 127     public static ModuleFinder limitedFinder() {
 128         ModuleFinder finder = limitedFinder;
 129         if (finder == null) {
 130             return unlimitedFinder();
 131         } else {
 132             return finder;
 133         }
 134     }
 135 
 136     /**
 137      * Initialize the module system, returning the boot layer.
 138      *
 139      * @see java.lang.System#initPhase2(boolean, boolean)
 140      */
 141     public static ModuleLayer boot() throws Exception {
 142 
 143         // Step 0: Command line options
 144 
 145         long t0 = System.nanoTime();
 146 
 147         ModuleFinder upgradeModulePath = finderFor("jdk.module.upgrade.path");
 148         ModuleFinder appModulePath = finderFor("jdk.module.path");
 149         boolean isPatched = patcher.hasPatches();
 150 
 151         String mainModule = System.getProperty("jdk.module.main");
 152         Set<String> addModules = addModules();
 153         Set<String> limitModules = limitModules();
 154 
 155         PrintStream traceOutput = null;
 156         String trace = getAndRemoveProperty("jdk.module.showModuleResolution");
 157         if (trace != null && Boolean.parseBoolean(trace))
 158             traceOutput = System.out;
 159 
 160 
 161         // Step 1: The observable system modules, either all system modules
 162         // or the system modules pre-generated for the initial module (the
 163         // initial module may be the unnamed module). If the system modules
 164         // are pre-generated for the initial module then resolution can be
 165         // skipped.
 166 
 167         long t1 = System.nanoTime();
 168 
 169         SystemModules systemModules = null;
 170         ModuleFinder systemModuleFinder;
 171 
 172         boolean haveModulePath = (appModulePath != null || upgradeModulePath != null);
 173         boolean needResolution = true;
 174 
 175         if (!haveModulePath && addModules.isEmpty() && limitModules.isEmpty()) {
 176             systemModules = SystemModuleFinders.systemModules(mainModule);
 177             if (systemModules != null && !isPatched && (traceOutput == null)) {
 178                 needResolution = false;
 179             }
 180         }
 181         if (systemModules == null) {
 182             // all system modules are observable
 183             systemModules = SystemModuleFinders.allSystemModules();
 184         }
 185         if (systemModules != null) {
 186             // images build
 187             systemModuleFinder = SystemModuleFinders.of(systemModules);
 188         } else {
 189             // exploded build or testing
 190             systemModules = new ExplodedSystemModules();
 191             systemModuleFinder = SystemModuleFinders.ofSystem();
 192         }
 193 
 194         Counters.add("jdk.module.boot.1.systemModulesTime", t1);
 195 
 196 
 197         // Step 2: Define and load java.base. This patches all classes loaded
 198         // to date so that they are members of java.base. Once java.base is
 199         // loaded then resources in java.base are available for error messages
 200         // needed from here on.
 201 
 202         long t2 = System.nanoTime();
 203 
 204         ModuleReference base = systemModuleFinder.find(JAVA_BASE).orElse(null);
 205         if (base == null)
 206             throw new InternalError(JAVA_BASE + " not found");
 207         URI baseUri = base.location().orElse(null);
 208         if (baseUri == null)
 209             throw new InternalError(JAVA_BASE + " does not have a location");
 210         BootLoader.loadModule(base);
 211         Modules.defineModule(null, base.descriptor(), baseUri);
 212 
 213         Counters.add("jdk.module.boot.2.defineBaseTime", t2);
 214 
 215 
 216         // Step 2a: Scan all modules when --validate-modules specified
 217 
 218         if (getAndRemoveProperty("jdk.module.validation") != null) {
 219             int errors = ModulePathValidator.scanAllModules(System.out);
 220             if (errors > 0) {
 221                 fail("Validation of module path failed");
 222             }
 223         }
 224 
 225 
 226         // Step 3: If resolution is needed then create the module finder and
 227         // the set of root modules to resolve.
 228 
 229         long t3 = System.nanoTime();
 230 
 231         ModuleFinder savedModuleFinder = null;
 232         ModuleFinder finder;
 233         Set<String> roots;
 234         if (needResolution) {
 235 
 236             // upgraded modules override the modules in the run-time image
 237             if (upgradeModulePath != null)
 238                 systemModuleFinder = ModuleFinder.compose(upgradeModulePath,
 239                                                           systemModuleFinder);
 240 
 241             // The module finder: [--upgrade-module-path] system [--module-path]
 242             if (appModulePath != null) {
 243                 finder = ModuleFinder.compose(systemModuleFinder, appModulePath);
 244             } else {
 245                 finder = systemModuleFinder;
 246             }
 247 
 248             // The root modules to resolve
 249             roots = new HashSet<>();
 250 
 251             // launcher -m option to specify the main/initial module
 252             if (mainModule != null)
 253                 roots.add(mainModule);
 254 
 255             // additional module(s) specified by --add-modules
 256             boolean addAllDefaultModules = false;
 257             boolean addAllSystemModules = false;
 258             boolean addAllApplicationModules = false;
 259             for (String mod : addModules) {
 260                 switch (mod) {
 261                     case ALL_DEFAULT:
 262                         addAllDefaultModules = true;
 263                         break;
 264                     case ALL_SYSTEM:
 265                         addAllSystemModules = true;
 266                         break;
 267                     case ALL_MODULE_PATH:
 268                         addAllApplicationModules = true;
 269                         break;
 270                     default:
 271                         roots.add(mod);
 272                 }
 273             }
 274 
 275             // --limit-modules
 276             savedModuleFinder = finder;
 277             if (!limitModules.isEmpty()) {
 278                 finder = limitFinder(finder, limitModules, roots);
 279             }
 280 
 281             // If there is no initial module specified then assume that the initial
 282             // module is the unnamed module of the application class loader. This
 283             // is implemented by resolving all observable modules that export an
 284             // API. Modules that have the DO_NOT_RESOLVE_BY_DEFAULT bit set in
 285             // their ModuleResolution attribute flags are excluded from the
 286             // default set of roots.
 287             if (mainModule == null || addAllDefaultModules) {
 288                 roots.addAll(DefaultRoots.compute(systemModuleFinder, finder));
 289             }
 290 
 291             // If `--add-modules ALL-SYSTEM` is specified then all observable system
 292             // modules will be resolved.
 293             if (addAllSystemModules) {
 294                 ModuleFinder f = finder;  // observable modules
 295                 systemModuleFinder.findAll()
 296                     .stream()
 297                     .map(ModuleReference::descriptor)
 298                     .map(ModuleDescriptor::name)
 299                     .filter(mn -> f.find(mn).isPresent())  // observable
 300                     .forEach(mn -> roots.add(mn));
 301             }
 302 
 303             // If `--add-modules ALL-MODULE-PATH` is specified then all observable
 304             // modules on the application module path will be resolved.
 305             if (appModulePath != null && addAllApplicationModules) {
 306                 ModuleFinder f = finder;  // observable modules
 307                 appModulePath.findAll()
 308                     .stream()
 309                     .map(ModuleReference::descriptor)
 310                     .map(ModuleDescriptor::name)
 311                     .filter(mn -> f.find(mn).isPresent())  // observable
 312                     .forEach(mn -> roots.add(mn));
 313             }
 314         } else {
 315             // no resolution case
 316             finder = systemModuleFinder;
 317             roots = null;
 318         }
 319 
 320         Counters.add("jdk.module.boot.3.optionsAndRootsTime", t3);
 321 
 322         // Step 4: Resolve the root modules, with service binding, to create
 323         // the configuration for the boot layer. If resolution is not needed
 324         // then create the configuration for the boot layer from the
 325         // readability graph created at link time.
 326 
 327         long t4 = System.nanoTime();
 328 
 329         Configuration cf;
 330         if (needResolution) {
 331             cf = JLMA.resolveAndBind(finder, roots, traceOutput);
 332         } else {
 333             Map<String, Set<String>> map = systemModules.moduleReads();
 334             cf = JLMA.newConfiguration(systemModuleFinder, map);
 335         }
 336 
 337         // check that modules specified to --patch-module are resolved
 338         if (isPatched) {
 339             patcher.patchedModules()
 340                     .stream()
 341                     .filter(mn -> !cf.findModule(mn).isPresent())
 342                     .forEach(mn -> warnUnknownModule(PATCH_MODULE, mn));
 343         }
 344 
 345         Counters.add("jdk.module.boot.4.resolveTime", t4);
 346 
 347 
 348         // Step 5: Map the modules in the configuration to class loaders.
 349         // The static configuration provides the mapping of standard and JDK
 350         // modules to the boot and platform loaders. All other modules (JDK
 351         // tool modules, and both explicit and automatic modules on the
 352         // application module path) are defined to the application class
 353         // loader.
 354 
 355         long t5 = System.nanoTime();
 356 
 357         // mapping of modules to class loaders
 358         Function<String, ClassLoader> clf = ModuleLoaderMap.mappingFunction(cf);
 359 
 360         // check that all modules to be mapped to the boot loader will be
 361         // loaded from the runtime image
 362         if (haveModulePath) {
 363             for (ResolvedModule resolvedModule : cf.modules()) {
 364                 ModuleReference mref = resolvedModule.reference();
 365                 String name = mref.descriptor().name();
 366                 ClassLoader cl = clf.apply(name);
 367                 if (cl == null) {
 368                     if (upgradeModulePath != null
 369                             && upgradeModulePath.find(name).isPresent())
 370                         fail(name + ": cannot be loaded from upgrade module path");
 371                     if (!systemModuleFinder.find(name).isPresent())
 372                         fail(name + ": cannot be loaded from application module path");
 373                 }
 374             }
 375         }
 376 
 377         // check for split packages in the modules mapped to the built-in loaders
 378         if (systemModules.hasSplitPackages() || isPatched || haveModulePath) {
 379             checkSplitPackages(cf, clf);
 380         }
 381 
 382         // load/register the modules with the built-in class loaders
 383         loadModules(cf, clf);
 384 
 385         Counters.add("jdk.module.boot.5.loadModulesTime", t5);
 386 
 387 
 388         // Step 6: Define all modules to the VM
 389 
 390         long t6 = System.nanoTime();
 391         ModuleLayer bootLayer = ModuleLayer.empty().defineModules(cf, clf);
 392         Counters.add("jdk.module.boot.6.layerCreateTime", t6);
 393 
 394 
 395         // Step 7: Miscellaneous
 396 
 397         // check incubating status
 398         if (systemModules.hasIncubatorModules() || haveModulePath) {
 399             checkIncubatingStatus(cf);
 400         }
 401 
 402         // --add-reads, --add-exports/--add-opens, and --illegal-access
 403         long t7 = System.nanoTime();
 404         addExtraReads(bootLayer);
 405         boolean extraExportsOrOpens = addExtraExportsAndOpens(bootLayer);
 406         addIllegalAccess(upgradeModulePath, systemModules, bootLayer, extraExportsOrOpens);
 407         Counters.add("jdk.module.boot.7.adjustModulesTime", t7);
 408 
 409         // save module finders for later use
 410         if (savedModuleFinder != null) {
 411             unlimitedFinder = new SafeModuleFinder(savedModuleFinder);
 412             if (savedModuleFinder != finder)
 413                 limitedFinder = new SafeModuleFinder(finder);
 414         }
 415 
 416         // total time to initialize
 417         Counters.add("jdk.module.boot.totalTime", t0);
 418         Counters.publish();
 419 
 420         return bootLayer;
 421     }
 422 
 423     /**
 424      * Load/register the modules to the built-in class loaders.
 425      */
 426     private static void loadModules(Configuration cf,
 427                                     Function<String, ClassLoader> clf) {
 428         for (ResolvedModule resolvedModule : cf.modules()) {
 429             ModuleReference mref = resolvedModule.reference();
 430             String name = resolvedModule.name();
 431             ClassLoader loader = clf.apply(name);
 432             if (loader == null) {
 433                 // skip java.base as it is already loaded
 434                 if (!name.equals(JAVA_BASE)) {
 435                     BootLoader.loadModule(mref);
 436                 }
 437             } else if (loader instanceof BuiltinClassLoader) {
 438                 ((BuiltinClassLoader) loader).loadModule(mref);
 439             }
 440         }
 441     }
 442 
 443     /**
 444      * Checks for split packages between modules defined to the built-in class
 445      * loaders.
 446      */
 447     private static void checkSplitPackages(Configuration cf,
 448                                            Function<String, ClassLoader> clf) {
 449         Map<String, String> packageToModule = new HashMap<>();
 450         for (ResolvedModule resolvedModule : cf.modules()) {
 451             ModuleDescriptor descriptor = resolvedModule.reference().descriptor();
 452             String name = descriptor.name();
 453             ClassLoader loader = clf.apply(name);
 454             if (loader == null || loader instanceof BuiltinClassLoader) {
 455                 for (String p : descriptor.packages()) {
 456                     String other = packageToModule.putIfAbsent(p, name);
 457                     if (other != null) {
 458                         String msg = "Package " + p + " in both module "
 459                                      + name + " and module " + other;
 460                         throw new LayerInstantiationException(msg);
 461                     }
 462                 }
 463             }
 464         }
 465     }
 466 
 467     /**
 468      * Returns a ModuleFinder that limits observability to the given root
 469      * modules, their transitive dependences, plus a set of other modules.
 470      */
 471     private static ModuleFinder limitFinder(ModuleFinder finder,
 472                                             Set<String> roots,
 473                                             Set<String> otherMods)
 474     {
 475         // resolve all root modules
 476         Configuration cf = Configuration.empty().resolve(finder,
 477                                                          ModuleFinder.of(),
 478                                                          roots);
 479 
 480         // module name -> reference
 481         Map<String, ModuleReference> map = new HashMap<>();
 482 
 483         // root modules and their transitive dependences
 484         cf.modules().stream()
 485             .map(ResolvedModule::reference)
 486             .forEach(mref -> map.put(mref.descriptor().name(), mref));
 487 
 488         // additional modules
 489         otherMods.stream()
 490             .map(finder::find)
 491             .flatMap(Optional::stream)
 492             .forEach(mref -> map.putIfAbsent(mref.descriptor().name(), mref));
 493 
 494         // set of modules that are observable
 495         Set<ModuleReference> mrefs = new HashSet<>(map.values());
 496 
 497         return new ModuleFinder() {
 498             @Override
 499             public Optional<ModuleReference> find(String name) {
 500                 return Optional.ofNullable(map.get(name));
 501             }
 502             @Override
 503             public Set<ModuleReference> findAll() {
 504                 return mrefs;
 505             }
 506         };
 507     }
 508 
 509     /**
 510      * Creates a finder from the module path that is the value of the given
 511      * system property and optionally patched by --patch-module
 512      */
 513     private static ModuleFinder finderFor(String prop) {
 514         String s = System.getProperty(prop);
 515         if (s == null) {
 516             return null;
 517         } else {
 518             String[] dirs = s.split(File.pathSeparator);
 519             Path[] paths = new Path[dirs.length];
 520             int i = 0;
 521             for (String dir: dirs) {
 522                 paths[i++] = Path.of(dir);
 523             }
 524             return ModulePath.of(patcher, paths);
 525         }
 526     }
 527 
 528     /**
 529      * Initialize the module patcher for the initial configuration passed on the
 530      * value of the --patch-module options.
 531      */
 532     private static ModulePatcher initModulePatcher() {
 533         Map<String, List<String>> map = decode("jdk.module.patch.",
 534                                                File.pathSeparator,
 535                                                false);
 536         return new ModulePatcher(map);
 537     }
 538 
 539     /**
 540      * Returns the set of module names specified by --add-module options.
 541      */
 542     private static Set<String> addModules() {
 543         String prefix = "jdk.module.addmods.";
 544         int index = 0;
 545         // the system property is removed after decoding
 546         String value = getAndRemoveProperty(prefix + index);
 547         if (value == null) {
 548             return Collections.emptySet();
 549         } else {
 550             Set<String> modules = new HashSet<>();
 551             while (value != null) {
 552                 for (String s : value.split(",")) {
 553                     if (!s.isEmpty())
 554                         modules.add(s);
 555                 }
 556                 index++;
 557                 value = getAndRemoveProperty(prefix + index);
 558             }
 559             return modules;
 560         }
 561     }
 562 
 563     /**
 564      * Returns the set of module names specified by --limit-modules.
 565      */
 566     private static Set<String> limitModules() {
 567         String value = getAndRemoveProperty("jdk.module.limitmods");
 568         if (value == null) {
 569             return Collections.emptySet();
 570         } else {
 571             Set<String> names = new HashSet<>();
 572             for (String name : value.split(",")) {
 573                 if (name.length() > 0) names.add(name);
 574             }
 575             return names;
 576         }
 577     }
 578 
 579     /**
 580      * Process the --add-reads options to add any additional read edges that
 581      * are specified on the command-line.
 582      */
 583     private static void addExtraReads(ModuleLayer bootLayer) {
 584 
 585         // decode the command line options
 586         Map<String, List<String>> map = decode("jdk.module.addreads.");
 587         if (map.isEmpty())
 588             return;
 589 
 590         for (Map.Entry<String, List<String>> e : map.entrySet()) {
 591 
 592             // the key is $MODULE
 593             String mn = e.getKey();
 594             Optional<Module> om = bootLayer.findModule(mn);
 595             if (!om.isPresent()) {
 596                 warnUnknownModule(ADD_READS, mn);
 597                 continue;
 598             }
 599             Module m = om.get();
 600 
 601             // the value is the set of other modules (by name)
 602             for (String name : e.getValue()) {
 603                 if (ALL_UNNAMED.equals(name)) {
 604                     Modules.addReadsAllUnnamed(m);
 605                 } else {
 606                     om = bootLayer.findModule(name);
 607                     if (om.isPresent()) {
 608                         Modules.addReads(m, om.get());
 609                     } else {
 610                         warnUnknownModule(ADD_READS, name);
 611                     }
 612                 }
 613             }
 614         }
 615     }
 616 
 617     /**
 618      * Process the --add-exports and --add-opens options to export/open
 619      * additional packages specified on the command-line.
 620      */
 621     private static boolean addExtraExportsAndOpens(ModuleLayer bootLayer) {
 622         boolean extraExportsOrOpens = false;
 623 
 624         // --add-exports
 625         String prefix = "jdk.module.addexports.";
 626         Map<String, List<String>> extraExports = decode(prefix);
 627         if (!extraExports.isEmpty()) {
 628             addExtraExportsOrOpens(bootLayer, extraExports, false);
 629             extraExportsOrOpens = true;
 630         }
 631 
 632 
 633         // --add-opens
 634         prefix = "jdk.module.addopens.";
 635         Map<String, List<String>> extraOpens = decode(prefix);
 636         if (!extraOpens.isEmpty()) {
 637             addExtraExportsOrOpens(bootLayer, extraOpens, true);
 638             extraExportsOrOpens = true;
 639         }
 640 
 641         return extraExportsOrOpens;
 642     }
 643 
 644     private static void addExtraExportsOrOpens(ModuleLayer bootLayer,
 645                                                Map<String, List<String>> map,
 646                                                boolean opens)
 647     {
 648         String option = opens ? ADD_OPENS : ADD_EXPORTS;
 649         for (Map.Entry<String, List<String>> e : map.entrySet()) {
 650 
 651             // the key is $MODULE/$PACKAGE
 652             String key = e.getKey();
 653             String[] s = key.split("/");
 654             if (s.length != 2)
 655                 fail(unableToParse(option, "<module>/<package>", key));
 656 
 657             String mn = s[0];
 658             String pn = s[1];
 659             if (mn.isEmpty() || pn.isEmpty())
 660                 fail(unableToParse(option, "<module>/<package>", key));
 661 
 662             // The exporting module is in the boot layer
 663             Module m;
 664             Optional<Module> om = bootLayer.findModule(mn);
 665             if (!om.isPresent()) {
 666                 warnUnknownModule(option, mn);
 667                 continue;
 668             }
 669 
 670             m = om.get();
 671 
 672             if (!m.getDescriptor().packages().contains(pn)) {
 673                 warn("package " + pn + " not in " + mn);
 674                 continue;
 675             }
 676 
 677             // the value is the set of modules to export to (by name)
 678             for (String name : e.getValue()) {
 679                 boolean allUnnamed = false;
 680                 Module other = null;
 681                 if (ALL_UNNAMED.equals(name)) {
 682                     allUnnamed = true;
 683                 } else {
 684                     om = bootLayer.findModule(name);
 685                     if (om.isPresent()) {
 686                         other = om.get();
 687                     } else {
 688                         warnUnknownModule(option, name);
 689                         continue;
 690                     }
 691                 }
 692                 if (allUnnamed) {
 693                     if (opens) {
 694                         Modules.addOpensToAllUnnamed(m, pn);
 695                     } else {
 696                         Modules.addExportsToAllUnnamed(m, pn);
 697                     }
 698                 } else {
 699                     if (opens) {
 700                         Modules.addOpens(m, pn, other);
 701                     } else {
 702                         Modules.addExports(m, pn, other);
 703                     }
 704                 }
 705 
 706             }
 707         }
 708     }
 709 
 710     /**
 711      * Process the --illegal-access option (and its default) to open packages
 712      * of system modules in the boot layer to code in unnamed modules.
 713      */
 714     private static void addIllegalAccess(ModuleFinder upgradeModulePath,
 715                                          SystemModules systemModules,
 716                                          ModuleLayer bootLayer,
 717                                          boolean extraExportsOrOpens) {
 718         String value = getAndRemoveProperty("jdk.module.illegalAccess");
 719         IllegalAccessLogger.Mode mode = IllegalAccessLogger.Mode.ONESHOT;
 720         if (value != null) {
 721             switch (value) {
 722                 case "deny":
 723                     return;
 724                 case "permit":
 725                     break;
 726                 case "warn":
 727                     mode = IllegalAccessLogger.Mode.WARN;
 728                     break;
 729                 case "debug":
 730                     mode = IllegalAccessLogger.Mode.DEBUG;
 731                     break;
 732                 default:
 733                     fail("Value specified to --illegal-access not recognized:"
 734                             + " '" + value + "'");
 735                     return;
 736             }
 737         }
 738         IllegalAccessLogger.Builder builder
 739             = new IllegalAccessLogger.Builder(mode, System.err);
 740 
 741         Map<String, Set<String>> map1 = systemModules.concealedPackagesToOpen();
 742         Map<String, Set<String>> map2 = systemModules.exportedPackagesToOpen();
 743         if (map1.isEmpty() && map2.isEmpty()) {
 744             // need to generate (exploded build)
 745             IllegalAccessMaps maps = IllegalAccessMaps.generate(limitedFinder());
 746             map1 = maps.concealedPackagesToOpen();
 747             map2 = maps.exportedPackagesToOpen();
 748         }
 749 
 750         // open specific packages in the system modules
 751         for (Module m : bootLayer.modules()) {
 752             ModuleDescriptor descriptor = m.getDescriptor();
 753             String name = m.getName();
 754 
 755             // skip open modules
 756             if (descriptor.isOpen()) {
 757                 continue;
 758             }
 759 
 760             // skip modules loaded from the upgrade module path
 761             if (upgradeModulePath != null
 762                 && upgradeModulePath.find(name).isPresent()) {
 763                 continue;
 764             }
 765 
 766             Set<String> concealedPackages = map1.getOrDefault(name, Set.of());
 767             Set<String> exportedPackages = map2.getOrDefault(name, Set.of());
 768 
 769             // refresh the set of concealed and exported packages if needed
 770             if (extraExportsOrOpens) {
 771                 concealedPackages = new HashSet<>(concealedPackages);
 772                 exportedPackages = new HashSet<>(exportedPackages);
 773                 Iterator<String> iterator = concealedPackages.iterator();
 774                 while (iterator.hasNext()) {
 775                     String pn = iterator.next();
 776                     if (m.isExported(pn, BootLoader.getUnnamedModule())) {
 777                         // concealed package is exported to ALL-UNNAMED
 778                         iterator.remove();
 779                         exportedPackages.add(pn);
 780                     }
 781                 }
 782                 iterator = exportedPackages.iterator();
 783                 while (iterator.hasNext()) {
 784                     String pn = iterator.next();
 785                     if (m.isOpen(pn, BootLoader.getUnnamedModule())) {
 786                         // exported package is opened to ALL-UNNAMED
 787                         iterator.remove();
 788                     }
 789                 }
 790             }
 791 
 792             // log reflective access to all types in concealed packages
 793             builder.logAccessToConcealedPackages(m, concealedPackages);
 794 
 795             // log reflective access to non-public members/types in exported packages
 796             builder.logAccessToExportedPackages(m, exportedPackages);
 797 
 798             // open the packages to unnamed modules
 799             JavaLangAccess jla = SharedSecrets.getJavaLangAccess();
 800             jla.addOpensToAllUnnamed(m, concat(concealedPackages.iterator(),
 801                                                exportedPackages.iterator()));
 802         }
 803 
 804         builder.complete();
 805     }
 806 
 807     /**
 808      * Decodes the values of --add-reads, -add-exports, --add-opens or
 809      * --patch-modules options that are encoded in system properties.
 810      *
 811      * @param prefix the system property prefix
 812      * @praam regex the regex for splitting the RHS of the option value
 813      */
 814     private static Map<String, List<String>> decode(String prefix,
 815                                                     String regex,
 816                                                     boolean allowDuplicates) {
 817         int index = 0;
 818         // the system property is removed after decoding
 819         String value = getAndRemoveProperty(prefix + index);
 820         if (value == null)
 821             return Collections.emptyMap();
 822 
 823         Map<String, List<String>> map = new HashMap<>();
 824 
 825         while (value != null) {
 826 
 827             int pos = value.indexOf('=');
 828             if (pos == -1)
 829                 fail(unableToParse(option(prefix), "<module>=<value>", value));
 830             if (pos == 0)
 831                 fail(unableToParse(option(prefix), "<module>=<value>", value));
 832 
 833             // key is <module> or <module>/<package>
 834             String key = value.substring(0, pos);
 835 
 836             String rhs = value.substring(pos+1);
 837             if (rhs.isEmpty())
 838                 fail(unableToParse(option(prefix), "<module>=<value>", value));
 839 
 840             // value is <module>(,<module>)* or <file>(<pathsep><file>)*
 841             if (!allowDuplicates && map.containsKey(key))
 842                 fail(key + " specified more than once to " + option(prefix));
 843             List<String> values = map.computeIfAbsent(key, k -> new ArrayList<>());
 844             int ntargets = 0;
 845             for (String s : rhs.split(regex)) {
 846                 if (!s.isEmpty()) {
 847                     values.add(s);
 848                     ntargets++;
 849                 }
 850             }
 851             if (ntargets == 0)
 852                 fail("Target must be specified: " + option(prefix) + " " + value);
 853 
 854             index++;
 855             value = getAndRemoveProperty(prefix + index);
 856         }
 857 
 858         return map;
 859     }
 860 
 861     /**
 862      * Decodes the values of --add-reads, -add-exports or --add-opens
 863      * which use the "," to separate the RHS of the option value.
 864      */
 865     private static Map<String, List<String>> decode(String prefix) {
 866         return decode(prefix, ",", true);
 867     }
 868 
 869     /**
 870      * Gets and remove the named system property
 871      */
 872     private static String getAndRemoveProperty(String key) {
 873         return (String)System.getProperties().remove(key);
 874     }
 875 
 876     /**
 877      * Checks incubating status of modules in the configuration
 878      */
 879     private static void checkIncubatingStatus(Configuration cf) {
 880         String incubating = null;
 881         for (ResolvedModule resolvedModule : cf.modules()) {
 882             ModuleReference mref = resolvedModule.reference();
 883 
 884             // emit warning if the WARN_INCUBATING module resolution bit set
 885             if (ModuleResolution.hasIncubatingWarning(mref)) {
 886                 String mn = mref.descriptor().name();
 887                 if (incubating == null) {
 888                     incubating = mn;
 889                 } else {
 890                     incubating += ", " + mn;
 891                 }
 892             }
 893         }
 894         if (incubating != null)
 895             warn("Using incubator modules: " + incubating);
 896     }
 897 
 898     /**
 899      * Throws a RuntimeException with the given message
 900      */
 901     static void fail(String m) {
 902         throw new RuntimeException(m);
 903     }
 904 
 905     static void warn(String m) {
 906         System.err.println("WARNING: " + m);
 907     }
 908 
 909     static void warnUnknownModule(String option, String mn) {
 910         warn("Unknown module: " + mn + " specified to " + option);
 911     }
 912 
 913     static String unableToParse(String option, String text, String value) {
 914         return "Unable to parse " +  option + " " + text + ": " + value;
 915     }
 916 
 917     private static final String ADD_MODULES  = "--add-modules";
 918     private static final String ADD_EXPORTS  = "--add-exports";
 919     private static final String ADD_OPENS    = "--add-opens";
 920     private static final String ADD_READS    = "--add-reads";
 921     private static final String PATCH_MODULE = "--patch-module";
 922 
 923 
 924     /*
 925      * Returns the command-line option name corresponds to the specified
 926      * system property prefix.
 927      */
 928     static String option(String prefix) {
 929         switch (prefix) {
 930             case "jdk.module.addexports.":
 931                 return ADD_EXPORTS;
 932             case "jdk.module.addopens.":
 933                 return ADD_OPENS;
 934             case "jdk.module.addreads.":
 935                 return ADD_READS;
 936             case "jdk.module.patch.":
 937                 return PATCH_MODULE;
 938             case "jdk.module.addmods.":
 939                 return ADD_MODULES;
 940             default:
 941                 throw new IllegalArgumentException(prefix);
 942         }
 943     }
 944 
 945     /**
 946      * Returns an iterator that yields all elements of the first iterator
 947      * followed by all the elements of the second iterator.
 948      */
 949     static <T> Iterator<T> concat(Iterator<T> iterator1, Iterator<T> iterator2) {
 950         return new Iterator<T>() {
 951             @Override
 952             public boolean hasNext() {
 953                 return iterator1.hasNext() || iterator2.hasNext();
 954             }
 955             @Override
 956             public T next() {
 957                 if (iterator1.hasNext()) return iterator1.next();
 958                 if (iterator2.hasNext()) return iterator2.next();
 959                 throw new NoSuchElementException();
 960             }
 961         };
 962     }
 963 
 964     /**
 965      * Wraps a (potentially not thread safe) ModuleFinder created during startup
 966      * for use after startup.
 967      */
 968     static class SafeModuleFinder implements ModuleFinder {
 969         private final Set<ModuleReference> mrefs;
 970         private volatile Map<String, ModuleReference> nameToModule;
 971 
 972         SafeModuleFinder(ModuleFinder finder) {
 973             this.mrefs = Collections.unmodifiableSet(finder.findAll());
 974         }
 975         @Override
 976         public Optional<ModuleReference> find(String name) {
 977             Objects.requireNonNull(name);
 978             Map<String, ModuleReference> nameToModule = this.nameToModule;
 979             if (nameToModule == null) {
 980                 this.nameToModule = nameToModule = mrefs.stream()
 981                         .collect(Collectors.toMap(m -> m.descriptor().name(),
 982                                                   Function.identity()));
 983             }
 984             return Optional.ofNullable(nameToModule.get(name));
 985         }
 986         @Override
 987         public Set<ModuleReference> findAll() {
 988             return mrefs;
 989         }
 990     }
 991 
 992     /**
 993      * Counters for startup performance analysis.
 994      */
 995     static class Counters {
 996         private static final boolean PUBLISH_COUNTERS;
 997         private static final boolean PRINT_COUNTERS;
 998         private static Map<String, Long> counters;
 999         static {
1000             String s = System.getProperty("jdk.module.boot.usePerfData");
1001             if (s == null) {
1002                 PUBLISH_COUNTERS = false;
1003                 PRINT_COUNTERS = false;
1004             } else {
1005                 PUBLISH_COUNTERS = true;
1006                 PRINT_COUNTERS = s.equals("debug");
1007                 counters = new LinkedHashMap<>();  // preserve insert order
1008             }
1009         }
1010 
1011         /**
1012          * Add a counter
1013          */
1014         static void add(String name, long start) {
1015             if (PUBLISH_COUNTERS || PRINT_COUNTERS) {
1016                 counters.put(name, (System.nanoTime() - start));
1017             }
1018         }
1019 
1020         /**
1021          * Publish the counters to the instrumentation buffer or stdout.
1022          */
1023         static void publish() {
1024             if (PUBLISH_COUNTERS || PRINT_COUNTERS) {
1025                 for (Map.Entry<String, Long> e : counters.entrySet()) {
1026                     String name = e.getKey();
1027                     long value = e.getValue();
1028                     if (PUBLISH_COUNTERS)
1029                         PerfCounter.newPerfCounter(name).set(value);
1030                     if (PRINT_COUNTERS)
1031                         System.out.println(name + " = " + value);
1032                 }
1033             }
1034         }
1035     }
1036 }