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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classFileStream.hpp"
  27 #include "classfile/classListParser.hpp"
  28 #include "classfile/classLoader.hpp"
  29 #include "classfile/classLoaderData.inline.hpp"
  30 #include "classfile/classLoaderExt.hpp"
  31 #include "classfile/compactHashtable.inline.hpp"
  32 #include "classfile/dictionary.hpp"
  33 #include "classfile/javaClasses.hpp"
  34 #include "classfile/symbolTable.hpp"
  35 #include "classfile/systemDictionary.hpp"
  36 #include "classfile/systemDictionaryShared.hpp"
  37 #include "classfile/verificationType.hpp"
  38 #include "classfile/vmSymbols.hpp"
  39 #include "logging/log.hpp"
  40 #include "memory/allocation.hpp"
  41 #include "memory/filemap.hpp"
  42 #include "memory/metadataFactory.hpp"
  43 #include "memory/metaspaceClosure.hpp"
  44 #include "memory/oopFactory.hpp"
  45 #include "memory/resourceArea.hpp"
  46 #include "oops/instanceKlass.hpp"
  47 #include "oops/klass.inline.hpp"
  48 #include "oops/objArrayOop.inline.hpp"
  49 #include "oops/oop.inline.hpp"
  50 #include "oops/typeArrayOop.inline.hpp"
  51 #include "runtime/handles.inline.hpp"
  52 #include "runtime/java.hpp"
  53 #include "runtime/javaCalls.hpp"
  54 #include "runtime/mutexLocker.hpp"
  55 #include "utilities/hashtable.inline.hpp"
  56 #include "utilities/stringUtils.hpp"
  57 
  58 
  59 objArrayOop SystemDictionaryShared::_shared_protection_domains  =  NULL;
  60 objArrayOop SystemDictionaryShared::_shared_jar_urls            =  NULL;
  61 objArrayOop SystemDictionaryShared::_shared_jar_manifests       =  NULL;
  62 
  63 oop SystemDictionaryShared::shared_protection_domain(int index) {
  64   return _shared_protection_domains->obj_at(index);
  65 }
  66 
  67 oop SystemDictionaryShared::shared_jar_url(int index) {
  68   return _shared_jar_urls->obj_at(index);
  69 }
  70 
  71 oop SystemDictionaryShared::shared_jar_manifest(int index) {
  72   return _shared_jar_manifests->obj_at(index);
  73 }
  74 
  75 
  76 Handle SystemDictionaryShared::get_shared_jar_manifest(int shared_path_index, TRAPS) {
  77   Handle manifest ;
  78   if (shared_jar_manifest(shared_path_index) == NULL) {
  79     SharedClassPathEntry* ent = FileMapInfo::shared_path(shared_path_index);
  80     long size = ent->manifest_size();
  81     if (size <= 0) {
  82       return Handle();
  83     }
  84 
  85     // ByteArrayInputStream bais = new ByteArrayInputStream(buf);
  86     const char* src = ent->manifest();
  87     assert(src != NULL, "No Manifest data");
  88     typeArrayOop buf = oopFactory::new_byteArray(size, CHECK_NH);
  89     typeArrayHandle bufhandle(THREAD, buf);
  90     ArrayAccess<>::arraycopy_from_native<jbyte>(reinterpret_cast<const jbyte*>(src),
  91                                                 buf, typeArrayOopDesc::element_offset<jbyte>(0), size);
  92 
  93     Handle bais = JavaCalls::construct_new_instance(SystemDictionary::ByteArrayInputStream_klass(),
  94                       vmSymbols::byte_array_void_signature(),
  95                       bufhandle, CHECK_NH);
  96 
  97     // manifest = new Manifest(bais)
  98     manifest = JavaCalls::construct_new_instance(SystemDictionary::Jar_Manifest_klass(),
  99                       vmSymbols::input_stream_void_signature(),
 100                       bais, CHECK_NH);
 101     atomic_set_shared_jar_manifest(shared_path_index, manifest());
 102   }
 103 
 104   manifest = Handle(THREAD, shared_jar_manifest(shared_path_index));
 105   assert(manifest.not_null(), "sanity");
 106   return manifest;
 107 }
 108 
 109 Handle SystemDictionaryShared::get_shared_jar_url(int shared_path_index, TRAPS) {
 110   Handle url_h;
 111   if (shared_jar_url(shared_path_index) == NULL) {
 112     JavaValue result(T_OBJECT);
 113     const char* path = FileMapInfo::shared_path_name(shared_path_index);
 114     Handle path_string = java_lang_String::create_from_str(path, CHECK_(url_h));
 115     Klass* classLoaders_klass =
 116         SystemDictionary::jdk_internal_loader_ClassLoaders_klass();
 117     JavaCalls::call_static(&result, classLoaders_klass,
 118                            vmSymbols::toFileURL_name(),
 119                            vmSymbols::toFileURL_signature(),
 120                            path_string, CHECK_(url_h));
 121 
 122     atomic_set_shared_jar_url(shared_path_index, (oop)result.get_jobject());
 123   }
 124 
 125   url_h = Handle(THREAD, shared_jar_url(shared_path_index));
 126   assert(url_h.not_null(), "sanity");
 127   return url_h;
 128 }
 129 
 130 Handle SystemDictionaryShared::get_package_name(Symbol* class_name, TRAPS) {
 131   ResourceMark rm(THREAD);
 132   Handle pkgname_string;
 133   char* pkgname = (char*) ClassLoader::package_from_name((const char*) class_name->as_C_string());
 134   if (pkgname != NULL) { // Package prefix found
 135     StringUtils::replace_no_expand(pkgname, "/", ".");
 136     pkgname_string = java_lang_String::create_from_str(pkgname,
 137                                                        CHECK_(pkgname_string));
 138   }
 139   return pkgname_string;
 140 }
 141 
 142 // Define Package for shared app classes from JAR file and also checks for
 143 // package sealing (all done in Java code)
 144 // See http://docs.oracle.com/javase/tutorial/deployment/jar/sealman.html
 145 void SystemDictionaryShared::define_shared_package(Symbol*  class_name,
 146                                                    Handle class_loader,
 147                                                    Handle manifest,
 148                                                    Handle url,
 149                                                    TRAPS) {
 150   assert(SystemDictionary::is_system_class_loader(class_loader()), "unexpected class loader");
 151   // get_package_name() returns a NULL handle if the class is in unnamed package
 152   Handle pkgname_string = get_package_name(class_name, CHECK);
 153   if (pkgname_string.not_null()) {
 154     Klass* app_classLoader_klass = SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass();
 155     JavaValue result(T_OBJECT);
 156     JavaCallArguments args(3);
 157     args.set_receiver(class_loader);
 158     args.push_oop(pkgname_string);
 159     args.push_oop(manifest);
 160     args.push_oop(url);
 161     JavaCalls::call_virtual(&result, app_classLoader_klass,
 162                             vmSymbols::defineOrCheckPackage_name(),
 163                             vmSymbols::defineOrCheckPackage_signature(),
 164                             &args,
 165                             CHECK);
 166   }
 167 }
 168 
 169 // Define Package for shared app/platform classes from named module
 170 void SystemDictionaryShared::define_shared_package(Symbol* class_name,
 171                                                    Handle class_loader,
 172                                                    ModuleEntry* mod_entry,
 173                                                    TRAPS) {
 174   assert(mod_entry != NULL, "module_entry should not be NULL");
 175   Handle module_handle(THREAD, mod_entry->module());
 176 
 177   Handle pkg_name = get_package_name(class_name, CHECK);
 178   assert(pkg_name.not_null(), "Package should not be null for class in named module");
 179 
 180   Klass* classLoader_klass;
 181   if (SystemDictionary::is_system_class_loader(class_loader())) {
 182     classLoader_klass = SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass();
 183   } else {
 184     assert(SystemDictionary::is_platform_class_loader(class_loader()), "unexpected classloader");
 185     classLoader_klass = SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass();
 186   }
 187 
 188   JavaValue result(T_OBJECT);
 189   JavaCallArguments args(2);
 190   args.set_receiver(class_loader);
 191   args.push_oop(pkg_name);
 192   args.push_oop(module_handle);
 193   JavaCalls::call_virtual(&result, classLoader_klass,
 194                           vmSymbols::definePackage_name(),
 195                           vmSymbols::definePackage_signature(),
 196                           &args,
 197                           CHECK);
 198 }
 199 
 200 // Get the ProtectionDomain associated with the CodeSource from the classloader.
 201 Handle SystemDictionaryShared::get_protection_domain_from_classloader(Handle class_loader,
 202                                                                       Handle url, TRAPS) {
 203   // CodeSource cs = new CodeSource(url, null);
 204   Handle cs = JavaCalls::construct_new_instance(SystemDictionary::CodeSource_klass(),
 205                   vmSymbols::url_code_signer_array_void_signature(),
 206                   url, Handle(), CHECK_NH);
 207 
 208   // protection_domain = SecureClassLoader.getProtectionDomain(cs);
 209   Klass* secureClassLoader_klass = SystemDictionary::SecureClassLoader_klass();
 210   JavaValue obj_result(T_OBJECT);
 211   JavaCalls::call_virtual(&obj_result, class_loader, secureClassLoader_klass,
 212                           vmSymbols::getProtectionDomain_name(),
 213                           vmSymbols::getProtectionDomain_signature(),
 214                           cs, CHECK_NH);
 215   return Handle(THREAD, (oop)obj_result.get_jobject());
 216 }
 217 
 218 // Returns the ProtectionDomain associated with the JAR file identified by the url.
 219 Handle SystemDictionaryShared::get_shared_protection_domain(Handle class_loader,
 220                                                             int shared_path_index,
 221                                                             Handle url,
 222                                                             TRAPS) {
 223   Handle protection_domain;
 224   if (shared_protection_domain(shared_path_index) == NULL) {
 225     Handle pd = get_protection_domain_from_classloader(class_loader, url, THREAD);
 226     atomic_set_shared_protection_domain(shared_path_index, pd());
 227   }
 228 
 229   // Acquire from the cache because if another thread beats the current one to
 230   // set the shared protection_domain and the atomic_set fails, the current thread
 231   // needs to get the updated protection_domain from the cache.
 232   protection_domain = Handle(THREAD, shared_protection_domain(shared_path_index));
 233   assert(protection_domain.not_null(), "sanity");
 234   return protection_domain;
 235 }
 236 
 237 // Returns the ProtectionDomain associated with the moduleEntry.
 238 Handle SystemDictionaryShared::get_shared_protection_domain(Handle class_loader,
 239                                                             ModuleEntry* mod, TRAPS) {
 240   ClassLoaderData *loader_data = mod->loader_data();
 241   Handle protection_domain;
 242   if (mod->shared_protection_domain() == NULL) {
 243     Symbol* location = mod->location();
 244     if (location != NULL) {
 245       Handle url_string = java_lang_String::create_from_symbol(
 246                                  location, CHECK_(protection_domain));
 247       JavaValue result(T_OBJECT);
 248       Klass* classLoaders_klass =
 249         SystemDictionary::jdk_internal_loader_ClassLoaders_klass();
 250       JavaCalls::call_static(&result, classLoaders_klass, vmSymbols::toFileURL_name(),
 251                                vmSymbols::toFileURL_signature(),
 252                                url_string, CHECK_(protection_domain));
 253       Handle url = Handle(THREAD, (oop)result.get_jobject());
 254 
 255       Handle pd = get_protection_domain_from_classloader(class_loader, url, THREAD);
 256       mod->set_shared_protection_domain(loader_data, pd);
 257     }
 258   }
 259 
 260   protection_domain = Handle(THREAD, mod->shared_protection_domain());
 261   assert(protection_domain.not_null(), "sanity");
 262   return protection_domain;
 263 }
 264 
 265 // Initializes the java.lang.Package and java.security.ProtectionDomain objects associated with
 266 // the given InstanceKlass.
 267 // Returns the ProtectionDomain for the InstanceKlass.
 268 Handle SystemDictionaryShared::init_security_info(Handle class_loader, InstanceKlass* ik, TRAPS) {
 269   Handle pd;
 270 
 271   if (ik != NULL) {
 272     int index = ik->shared_classpath_index();
 273     assert(index >= 0, "Sanity");
 274     SharedClassPathEntry* ent = FileMapInfo::shared_path(index);
 275     Symbol* class_name = ik->name();
 276 
 277     if (ent->is_modules_image()) {
 278       // For shared app/platform classes originated from the run-time image:
 279       //   The ProtectionDomains are cached in the corresponding ModuleEntries
 280       //   for fast access by the VM.
 281       ResourceMark rm;
 282       ClassLoaderData *loader_data =
 283                 ClassLoaderData::class_loader_data(class_loader());
 284       PackageEntryTable* pkgEntryTable = loader_data->packages();
 285       TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_(pd));
 286       if (pkg_name != NULL) {
 287         PackageEntry* pkg_entry = pkgEntryTable->lookup_only(pkg_name);
 288         if (pkg_entry != NULL) {
 289           ModuleEntry* mod_entry = pkg_entry->module();
 290           pd = get_shared_protection_domain(class_loader, mod_entry, THREAD);
 291           define_shared_package(class_name, class_loader, mod_entry, CHECK_(pd));
 292         }
 293       }
 294     } else {
 295       // For shared app/platform classes originated from JAR files on the class path:
 296       //   Each of the 3 SystemDictionaryShared::_shared_xxx arrays has the same length
 297       //   as the shared classpath table in the shared archive (see
 298       //   FileMap::_shared_path_table in filemap.hpp for details).
 299       //
 300       //   If a shared InstanceKlass k is loaded from the class path, let
 301       //
 302       //     index = k->shared_classpath_index():
 303       //
 304       //   FileMap::_shared_path_table[index] identifies the JAR file that contains k.
 305       //
 306       //   k's protection domain is:
 307       //
 308       //     ProtectionDomain pd = _shared_protection_domains[index];
 309       //
 310       //   and k's Package is initialized using
 311       //
 312       //     manifest = _shared_jar_manifests[index];
 313       //     url = _shared_jar_urls[index];
 314       //     define_shared_package(class_name, class_loader, manifest, url, CHECK_(pd));
 315       //
 316       //   Note that if an element of these 3 _shared_xxx arrays is NULL, it will be initialized by
 317       //   the corresponding SystemDictionaryShared::get_shared_xxx() function.
 318       Handle manifest = get_shared_jar_manifest(index, CHECK_(pd));
 319       Handle url = get_shared_jar_url(index, CHECK_(pd));
 320       define_shared_package(class_name, class_loader, manifest, url, CHECK_(pd));
 321       pd = get_shared_protection_domain(class_loader, index, url, CHECK_(pd));
 322     }
 323   }
 324   return pd;
 325 }
 326 
 327 bool SystemDictionaryShared::is_sharing_possible(ClassLoaderData* loader_data) {
 328   oop class_loader = loader_data->class_loader();
 329   return (class_loader == NULL ||
 330           SystemDictionary::is_system_class_loader(class_loader) ||
 331           SystemDictionary::is_platform_class_loader(class_loader));
 332 }
 333 
 334 // Currently AppCDS only archives classes from the run-time image, the
 335 // -Xbootclasspath/a path, the class path, and the module path.
 336 //
 337 // Check if a shared class can be loaded by the specific classloader. Following
 338 // are the "visible" archived classes for different classloaders.
 339 //
 340 // NULL classloader:
 341 //   - see SystemDictionary::is_shared_class_visible()
 342 // Platform classloader:
 343 //   - Module class from runtime image. ModuleEntry must be defined in the
 344 //     classloader.
 345 // App classloader:
 346 //   - Module Class from runtime image and module path. ModuleEntry must be defined in the
 347 //     classloader.
 348 //   - Class from -cp. The class must have no PackageEntry defined in any of the
 349 //     boot/platform/app classloader, or must be in the unnamed module defined in the
 350 //     AppClassLoader.
 351 bool SystemDictionaryShared::is_shared_class_visible_for_classloader(
 352                                                      InstanceKlass* ik,
 353                                                      Handle class_loader,
 354                                                      const char* pkg_string,
 355                                                      Symbol* pkg_name,
 356                                                      PackageEntry* pkg_entry,
 357                                                      ModuleEntry* mod_entry,
 358                                                      TRAPS) {
 359   assert(class_loader.not_null(), "Class loader should not be NULL");
 360   assert(Universe::is_module_initialized(), "Module system is not initialized");
 361   ResourceMark rm(THREAD);
 362 
 363   int path_index = ik->shared_classpath_index();
 364   SharedClassPathEntry* ent =
 365             (SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
 366 
 367   if (SystemDictionary::is_platform_class_loader(class_loader())) {
 368     assert(ent != NULL, "shared class for PlatformClassLoader should have valid SharedClassPathEntry");
 369     // The PlatformClassLoader can only load archived class originated from the
 370     // run-time image. The class' PackageEntry/ModuleEntry must be
 371     // defined by the PlatformClassLoader.
 372     if (mod_entry != NULL) {
 373       // PackageEntry/ModuleEntry is found in the classloader. Check if the
 374       // ModuleEntry's location agrees with the archived class' origination.
 375       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
 376         return true; // Module class from the runtime image
 377       }
 378     }
 379   } else if (SystemDictionary::is_system_class_loader(class_loader())) {
 380     assert(ent != NULL, "shared class for system loader should have valid SharedClassPathEntry");
 381     if (pkg_string == NULL) {
 382       // The archived class is in the unnamed package. Currently, the boot image
 383       // does not contain any class in the unnamed package.
 384       assert(!ent->is_modules_image(), "Class in the unnamed package must be from the classpath");
 385       if (path_index >= ClassLoaderExt::app_class_paths_start_index()) {
 386         assert(path_index < ClassLoaderExt::app_module_paths_start_index(), "invalid path_index");
 387         return true;
 388       }
 389     } else {
 390       // Check if this is from a PackageEntry/ModuleEntry defined in the AppClassloader.
 391       if (pkg_entry == NULL) {
 392         // It's not guaranteed that the class is from the classpath if the
 393         // PackageEntry cannot be found from the AppClassloader. Need to check
 394         // the boot and platform classloader as well.
 395         if (get_package_entry(pkg_name, ClassLoaderData::class_loader_data_or_null(SystemDictionary::java_platform_loader())) == NULL &&
 396             get_package_entry(pkg_name, ClassLoaderData::the_null_class_loader_data()) == NULL) {
 397           // The PackageEntry is not defined in any of the boot/platform/app classloaders.
 398           // The archived class must from -cp path and not from the runtime image.
 399           if (!ent->is_modules_image() && path_index >= ClassLoaderExt::app_class_paths_start_index() &&
 400                                           path_index < ClassLoaderExt::app_module_paths_start_index()) {
 401             return true;
 402           }
 403         }
 404       } else if (mod_entry != NULL) {
 405         // The package/module is defined in the AppClassLoader. We support
 406         // archiving application module class from the runtime image or from
 407         // a named module from a module path.
 408         // Packages from the -cp path are in the unnamed_module.
 409         if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
 410           // shared module class from runtime image
 411           return true;
 412         } else if (pkg_entry->in_unnamed_module() && path_index >= ClassLoaderExt::app_class_paths_start_index() &&
 413             path_index < ClassLoaderExt::app_module_paths_start_index()) {
 414           // shared class from -cp
 415           DEBUG_ONLY( \
 416             ClassLoaderData* loader_data = class_loader_data(class_loader); \
 417             assert(mod_entry == loader_data->unnamed_module(), "the unnamed module is not defined in the classloader");)
 418           return true;
 419         } else {
 420           if(!pkg_entry->in_unnamed_module() &&
 421               (path_index >= ClassLoaderExt::app_module_paths_start_index())&&
 422               (path_index < FileMapInfo::get_number_of_shared_paths()) &&
 423               (strcmp(ent->name(), ClassLoader::skip_uri_protocol(mod_entry->location()->as_C_string())) == 0)) {
 424             // shared module class from module path
 425             return true;
 426           } else {
 427             assert(path_index < FileMapInfo::get_number_of_shared_paths(), "invalid path_index");
 428           }
 429         }
 430       }
 431     }
 432   } else {
 433     // TEMP: if a shared class can be found by a custom loader, consider it visible now.
 434     // FIXME: is this actually correct?
 435     return true;
 436   }
 437   return false;
 438 }
 439 
 440 // The following stack shows how this code is reached:
 441 //
 442 //   [0] SystemDictionaryShared::find_or_load_shared_class()
 443 //   [1] JVM_FindLoadedClass
 444 //   [2] java.lang.ClassLoader.findLoadedClass0()
 445 //   [3] java.lang.ClassLoader.findLoadedClass()
 446 //   [4] jdk.internal.loader.BuiltinClassLoader.loadClassOrNull()
 447 //   [5] jdk.internal.loader.BuiltinClassLoader.loadClass()
 448 //   [6] jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(), or
 449 //       jdk.internal.loader.ClassLoaders$PlatformClassLoader.loadClass()
 450 //
 451 // AppCDS supports fast class loading for these 2 built-in class loaders:
 452 //    jdk.internal.loader.ClassLoaders$PlatformClassLoader
 453 //    jdk.internal.loader.ClassLoaders$AppClassLoader
 454 // with the following assumptions (based on the JDK core library source code):
 455 //
 456 // [a] these two loaders use the BuiltinClassLoader.loadClassOrNull() to
 457 //     load the named class.
 458 // [b] BuiltinClassLoader.loadClassOrNull() first calls findLoadedClass(name).
 459 // [c] At this point, if we can find the named class inside the
 460 //     shared_dictionary, we can perform further checks (see
 461 //     is_shared_class_visible_for_classloader() to ensure that this class
 462 //     was loaded by the same class loader during dump time.
 463 //
 464 // Given these assumptions, we intercept the findLoadedClass() call to invoke
 465 // SystemDictionaryShared::find_or_load_shared_class() to load the shared class from
 466 // the archive for the 2 built-in class loaders. This way,
 467 // we can improve start-up because we avoid decoding the classfile,
 468 // and avoid delegating to the parent loader.
 469 //
 470 // NOTE: there's a lot of assumption about the Java code. If any of that change, this
 471 // needs to be redesigned.
 472 
 473 InstanceKlass* SystemDictionaryShared::find_or_load_shared_class(
 474                  Symbol* name, Handle class_loader, TRAPS) {
 475   InstanceKlass* k = NULL;
 476   if (UseSharedSpaces) {
 477     if (!FileMapInfo::current_info()->header()->has_platform_or_app_classes()) {
 478       return NULL;
 479     }
 480 
 481     if (shared_dictionary() != NULL &&
 482         (SystemDictionary::is_system_class_loader(class_loader()) ||
 483          SystemDictionary::is_platform_class_loader(class_loader()))) {
 484       // Fix for 4474172; see evaluation for more details
 485       class_loader = Handle(
 486         THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 487       ClassLoaderData *loader_data = register_loader(class_loader);
 488       Dictionary* dictionary = loader_data->dictionary();
 489 
 490       unsigned int d_hash = dictionary->compute_hash(name);
 491 
 492       bool DoObjectLock = true;
 493       if (is_parallelCapable(class_loader)) {
 494         DoObjectLock = false;
 495       }
 496 
 497       // Make sure we are synchronized on the class loader before we proceed
 498       //
 499       // Note: currently, find_or_load_shared_class is called only from
 500       // JVM_FindLoadedClass and used for PlatformClassLoader and AppClassLoader,
 501       // which are parallel-capable loaders, so this lock is NOT taken.
 502       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 503       check_loader_lock_contention(lockObject, THREAD);
 504       ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 505 
 506       {
 507         MutexLocker mu(SystemDictionary_lock, THREAD);
 508         Klass* check = find_class(d_hash, name, dictionary);
 509         if (check != NULL) {
 510           return InstanceKlass::cast(check);
 511         }
 512       }
 513 
 514       k = load_shared_class_for_builtin_loader(name, class_loader, THREAD);
 515       if (k != NULL) {
 516         define_instance_class(k, CHECK_NULL);
 517       }
 518     }
 519   }
 520   return k;
 521 }
 522 
 523 InstanceKlass* SystemDictionaryShared::load_shared_class_for_builtin_loader(
 524                  Symbol* class_name, Handle class_loader, TRAPS) {
 525   assert(UseSharedSpaces, "must be");
 526   assert(shared_dictionary() != NULL, "already checked");
 527   Klass* k = shared_dictionary()->find_class_for_builtin_loader(class_name);
 528 
 529   if (k != NULL) {
 530     InstanceKlass* ik = InstanceKlass::cast(k);
 531     if ((ik->is_shared_app_class() &&
 532          SystemDictionary::is_system_class_loader(class_loader()))  ||
 533         (ik->is_shared_platform_class() &&
 534          SystemDictionary::is_platform_class_loader(class_loader()))) {
 535       Handle protection_domain =
 536         SystemDictionaryShared::init_security_info(class_loader, ik, CHECK_NULL);
 537       return load_shared_class(ik, class_loader, protection_domain, THREAD);
 538     }
 539   }
 540 
 541   return NULL;
 542 }
 543 
 544 void SystemDictionaryShared::oops_do(OopClosure* f) {
 545   f->do_oop((oop*)&_shared_protection_domains);
 546   f->do_oop((oop*)&_shared_jar_urls);
 547   f->do_oop((oop*)&_shared_jar_manifests);
 548 }
 549 
 550 void SystemDictionaryShared::allocate_shared_protection_domain_array(int size, TRAPS) {
 551   if (_shared_protection_domains == NULL) {
 552     _shared_protection_domains = oopFactory::new_objArray(
 553         SystemDictionary::ProtectionDomain_klass(), size, CHECK);
 554   }
 555 }
 556 
 557 void SystemDictionaryShared::allocate_shared_jar_url_array(int size, TRAPS) {
 558   if (_shared_jar_urls == NULL) {
 559     _shared_jar_urls = oopFactory::new_objArray(
 560         SystemDictionary::URL_klass(), size, CHECK);
 561   }
 562 }
 563 
 564 void SystemDictionaryShared::allocate_shared_jar_manifest_array(int size, TRAPS) {
 565   if (_shared_jar_manifests == NULL) {
 566     _shared_jar_manifests = oopFactory::new_objArray(
 567         SystemDictionary::Jar_Manifest_klass(), size, CHECK);
 568   }
 569 }
 570 
 571 void SystemDictionaryShared::allocate_shared_data_arrays(int size, TRAPS) {
 572   allocate_shared_protection_domain_array(size, CHECK);
 573   allocate_shared_jar_url_array(size, CHECK);
 574   allocate_shared_jar_manifest_array(size, CHECK);
 575 }
 576 
 577 // This function is called for loading only UNREGISTERED classes
 578 InstanceKlass* SystemDictionaryShared::lookup_from_stream(const Symbol* class_name,
 579                                                           Handle class_loader,
 580                                                           Handle protection_domain,
 581                                                           const ClassFileStream* cfs,
 582                                                           TRAPS) {
 583   if (shared_dictionary() == NULL) {
 584     return NULL;
 585   }
 586   if (class_name == NULL) {  // don't do this for anonymous classes
 587     return NULL;
 588   }
 589   if (class_loader.is_null() ||
 590       SystemDictionary::is_system_class_loader(class_loader()) ||
 591       SystemDictionary::is_platform_class_loader(class_loader())) {
 592     // Do nothing for the BUILTIN loaders.
 593     return NULL;
 594   }
 595 
 596   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
 597   Klass* k;
 598 
 599   { // UNREGISTERED loader
 600     if (!shared_dictionary()->class_exists_for_unregistered_loader(class_name)) {
 601       // No classes of this name for unregistered loaders.
 602       return NULL;
 603     }
 604 
 605     int clsfile_size  = cfs->length();
 606     int clsfile_crc32 = ClassLoader::crc32(0, (const char*)cfs->buffer(), cfs->length());
 607 
 608     k = shared_dictionary()->find_class_for_unregistered_loader(class_name,
 609                                                                 clsfile_size, clsfile_crc32);
 610   }
 611 
 612   if (k == NULL) { // not archived
 613     return NULL;
 614   }
 615 
 616   return acquire_class_for_current_thread(InstanceKlass::cast(k), class_loader,
 617                                           protection_domain, THREAD);
 618 }
 619 
 620 InstanceKlass* SystemDictionaryShared::acquire_class_for_current_thread(
 621                    InstanceKlass *ik,
 622                    Handle class_loader,
 623                    Handle protection_domain,
 624                    TRAPS) {
 625   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
 626 
 627   {
 628     MutexLocker mu(SharedDictionary_lock, THREAD);
 629     if (ik->class_loader_data() != NULL) {
 630       //    ik is already loaded (by this loader or by a different loader)
 631       // or ik is being loaded by a different thread (by this loader or by a different loader)
 632       return NULL;
 633     }
 634 
 635     // No other thread has acquired this yet, so give it to *this thread*
 636     ik->set_class_loader_data(loader_data);
 637   }
 638 
 639   // No longer holding SharedDictionary_lock
 640   // No need to lock, as <ik> can be held only by a single thread.
 641   loader_data->add_class(ik);
 642 
 643   // Load and check super/interfaces, restore unsharable info
 644   InstanceKlass* shared_klass = load_shared_class(ik, class_loader, protection_domain, THREAD);
 645   if (shared_klass == NULL || HAS_PENDING_EXCEPTION) {
 646     // TODO: clean up <ik> so it can be used again
 647     return NULL;
 648   }
 649 
 650   return shared_klass;
 651 }
 652 
 653 bool SystemDictionaryShared::add_non_builtin_klass(Symbol* name,
 654                                                    ClassLoaderData* loader_data,
 655                                                    InstanceKlass* k,
 656                                                    TRAPS) {
 657   assert(DumpSharedSpaces, "only when dumping");
 658   assert(boot_loader_dictionary() != NULL, "must be");
 659 
 660   if (boot_loader_dictionary()->add_non_builtin_klass(name, loader_data, k)) {
 661     MutexLocker mu_r(Compile_lock, THREAD); // not really necessary, but add_to_hierarchy asserts this.
 662     add_to_hierarchy(k, CHECK_0);
 663     return true;
 664   }
 665   return false;
 666 }
 667 
 668 // This function is called to resolve the super/interfaces of shared classes for
 669 // non-built-in loaders. E.g., ChildClass in the below example
 670 // where "super:" (and optionally "interface:") have been specified.
 671 //
 672 // java/lang/Object id: 0
 673 // Interface   id: 2 super: 0 source: cust.jar
 674 // ChildClass  id: 4 super: 0 interfaces: 2 source: cust.jar
 675 Klass* SystemDictionaryShared::dump_time_resolve_super_or_fail(
 676     Symbol* child_name, Symbol* class_name, Handle class_loader,
 677     Handle protection_domain, bool is_superclass, TRAPS) {
 678 
 679   assert(DumpSharedSpaces, "only when dumping");
 680 
 681   ClassListParser* parser = ClassListParser::instance();
 682   if (parser == NULL) {
 683     // We're still loading the well-known classes, before the ClassListParser is created.
 684     return NULL;
 685   }
 686   if (child_name->equals(parser->current_class_name())) {
 687     // When this function is called, all the numbered super and interface types
 688     // must have already been loaded. Hence this function is never recursively called.
 689     if (is_superclass) {
 690       return parser->lookup_super_for_current_class(class_name);
 691     } else {
 692       return parser->lookup_interface_for_current_class(class_name);
 693     }
 694   } else {
 695     // The VM is not trying to resolve a super type of parser->current_class_name().
 696     // Instead, it's resolving an error class (because parser->current_class_name() has
 697     // failed parsing or verification). Don't do anything here.
 698     return NULL;
 699   }
 700 }
 701 
 702 struct SharedMiscInfo {
 703   Klass* _klass;
 704   int _clsfile_size;
 705   int _clsfile_crc32;
 706 };
 707 
 708 static GrowableArray<SharedMiscInfo>* misc_info_array = NULL;
 709 
 710 void SystemDictionaryShared::set_shared_class_misc_info(Klass* k, ClassFileStream* cfs) {
 711   assert(DumpSharedSpaces, "only when dumping");
 712   int clsfile_size  = cfs->length();
 713   int clsfile_crc32 = ClassLoader::crc32(0, (const char*)cfs->buffer(), cfs->length());
 714 
 715   if (misc_info_array == NULL) {
 716     misc_info_array = new (ResourceObj::C_HEAP, mtClass) GrowableArray<SharedMiscInfo>(20, /*c heap*/ true);
 717   }
 718 
 719   SharedMiscInfo misc_info;
 720   DEBUG_ONLY({
 721       for (int i=0; i<misc_info_array->length(); i++) {
 722         misc_info = misc_info_array->at(i);
 723         assert(misc_info._klass != k, "cannot call set_shared_class_misc_info twice for the same class");
 724       }
 725     });
 726 
 727   misc_info._klass = k;
 728   misc_info._clsfile_size = clsfile_size;
 729   misc_info._clsfile_crc32 = clsfile_crc32;
 730 
 731   misc_info_array->append(misc_info);
 732 }
 733 
 734 void SystemDictionaryShared::init_shared_dictionary_entry(Klass* k, DictionaryEntry* ent) {
 735   SharedDictionaryEntry* entry = (SharedDictionaryEntry*)ent;
 736   entry->_id = -1;
 737   entry->_clsfile_size = -1;
 738   entry->_clsfile_crc32 = -1;
 739   entry->_verifier_constraints = NULL;
 740   entry->_verifier_constraint_flags = NULL;
 741 
 742   if (misc_info_array != NULL) {
 743     for (int i=0; i<misc_info_array->length(); i++) {
 744       SharedMiscInfo misc_info = misc_info_array->at(i);
 745       if (misc_info._klass == k) {
 746         entry->_clsfile_size = misc_info._clsfile_size;
 747         entry->_clsfile_crc32 = misc_info._clsfile_crc32;
 748         misc_info_array->remove_at(i);
 749         return;
 750       }
 751     }
 752   }
 753 }
 754 
 755 bool SystemDictionaryShared::add_verification_constraint(Klass* k, Symbol* name,
 756          Symbol* from_name, bool from_field_is_protected, bool from_is_array, bool from_is_object) {
 757   assert(DumpSharedSpaces, "called at dump time only");
 758 
 759   // Skip anonymous classes, which are not archived as they are not in
 760   // dictionary (see assert_no_anonymoys_classes_in_dictionaries() in
 761   // VM_PopulateDumpSharedSpace::doit()).
 762   if (k->class_loader_data()->is_anonymous()) {
 763     return true; // anonymous classes are not archived, skip
 764   }
 765 
 766   SharedDictionaryEntry* entry = ((SharedDictionary*)(k->class_loader_data()->dictionary()))->find_entry_for(k);
 767   ResourceMark rm;
 768   // Lambda classes are not archived and will be regenerated at runtime.
 769   if (entry == NULL && strstr(k->name()->as_C_string(), "Lambda$") != NULL) {
 770     return true;
 771   }
 772   assert(entry != NULL, "class should be in dictionary before being verified");
 773   entry->add_verification_constraint(name, from_name, from_field_is_protected,
 774                                      from_is_array, from_is_object);
 775   if (entry->is_builtin()) {
 776     // For builtin class loaders, we can try to complete the verification check at dump time,
 777     // because we can resolve all the constraint classes.
 778     return false;
 779   } else {
 780     // For non-builtin class loaders, we cannot complete the verification check at dump time,
 781     // because at dump time we don't know how to resolve classes for such loaders.
 782     return true;
 783   }
 784 }
 785 
 786 void SystemDictionaryShared::finalize_verification_constraints() {
 787   boot_loader_dictionary()->finalize_verification_constraints();
 788 }
 789 
 790 void SystemDictionaryShared::check_verification_constraints(InstanceKlass* klass,
 791                                                              TRAPS) {
 792   assert(!DumpSharedSpaces && UseSharedSpaces, "called at run time with CDS enabled only");
 793   SharedDictionaryEntry* entry = shared_dictionary()->find_entry_for(klass);
 794   assert(entry != NULL, "call this only for shared classes");
 795   entry->check_verification_constraints(klass, THREAD);
 796 }
 797 
 798 SharedDictionaryEntry* SharedDictionary::find_entry_for(Klass* klass) {
 799   Symbol* class_name = klass->name();
 800   unsigned int hash = compute_hash(class_name);
 801   int index = hash_to_index(hash);
 802 
 803   for (SharedDictionaryEntry* entry = bucket(index);
 804                               entry != NULL;
 805                               entry = entry->next()) {
 806     if (entry->hash() == hash && entry->literal() == klass) {
 807       return entry;
 808     }
 809   }
 810 
 811   return NULL;
 812 }
 813 
 814 void SharedDictionary::finalize_verification_constraints() {
 815   int bytes = 0, count = 0;
 816   for (int index = 0; index < table_size(); index++) {
 817     for (SharedDictionaryEntry *probe = bucket(index);
 818                                 probe != NULL;
 819                                probe = probe->next()) {
 820       int n = probe->finalize_verification_constraints();
 821       if (n > 0) {
 822         bytes += n;
 823         count ++;
 824       }
 825     }
 826   }
 827   if (log_is_enabled(Info, cds, verification)) {
 828     double avg = 0;
 829     if (count > 0) {
 830       avg = double(bytes) / double(count);
 831     }
 832     log_info(cds, verification)("Recorded verification constraints for %d classes = %d bytes (avg = %.2f bytes) ", count, bytes, avg);
 833   }
 834 }
 835 
 836 void SharedDictionaryEntry::add_verification_constraint(Symbol* name,
 837          Symbol* from_name, bool from_field_is_protected, bool from_is_array, bool from_is_object) {
 838   if (_verifier_constraints == NULL) {
 839     _verifier_constraints = new(ResourceObj::C_HEAP, mtClass) GrowableArray<Symbol*>(8, true, mtClass);
 840   }
 841   if (_verifier_constraint_flags == NULL) {
 842     _verifier_constraint_flags = new(ResourceObj::C_HEAP, mtClass) GrowableArray<char>(4, true, mtClass);
 843   }
 844   GrowableArray<Symbol*>* vc_array = (GrowableArray<Symbol*>*)_verifier_constraints;
 845   for (int i=0; i<vc_array->length(); i+= 2) {
 846     if (name      == vc_array->at(i) &&
 847         from_name == vc_array->at(i+1)) {
 848       return;
 849     }
 850   }
 851   vc_array->append(name);
 852   vc_array->append(from_name);
 853 
 854   GrowableArray<char>* vcflags_array = (GrowableArray<char>*)_verifier_constraint_flags;
 855   char c = 0;
 856   c |= from_field_is_protected ? FROM_FIELD_IS_PROTECTED : 0;
 857   c |= from_is_array           ? FROM_IS_ARRAY           : 0;
 858   c |= from_is_object          ? FROM_IS_OBJECT          : 0;
 859   vcflags_array->append(c);
 860 
 861   if (log_is_enabled(Trace, cds, verification)) {
 862     ResourceMark rm;
 863     log_trace(cds, verification)("add_verification_constraint: %s: %s must be subclass of %s",
 864                                  instance_klass()->external_name(), from_name->as_klass_external_name(),
 865                                  name->as_klass_external_name());
 866   }
 867 }
 868 
 869 int SharedDictionaryEntry::finalize_verification_constraints() {
 870   assert(DumpSharedSpaces, "called at dump time only");
 871   Thread* THREAD = Thread::current();
 872   ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
 873   GrowableArray<Symbol*>* vc_array = (GrowableArray<Symbol*>*)_verifier_constraints;
 874   GrowableArray<char>* vcflags_array = (GrowableArray<char>*)_verifier_constraint_flags;
 875 
 876   if (vc_array != NULL) {
 877     if (log_is_enabled(Trace, cds, verification)) {
 878       ResourceMark rm;
 879       log_trace(cds, verification)("finalize_verification_constraint: %s",
 880                                    literal()->external_name());
 881     }
 882 
 883     // Copy the constraints from C_HEAP-alloced GrowableArrays to Metaspace-alloced
 884     // Arrays
 885     int size = 0;
 886     {
 887       // FIXME: change this to be done after relocation, so we can use symbol offset??
 888       int length = vc_array->length();
 889       Array<Symbol*>* out = MetadataFactory::new_array<Symbol*>(loader_data, length, 0, THREAD);
 890       assert(out != NULL, "Dump time allocation failure would have aborted VM");
 891       for (int i=0; i<length; i++) {
 892         out->at_put(i, vc_array->at(i));
 893       }
 894       _verifier_constraints = out;
 895       size += out->size() * BytesPerWord;
 896       delete vc_array;
 897     }
 898     {
 899       int length = vcflags_array->length();
 900       Array<char>* out = MetadataFactory::new_array<char>(loader_data, length, 0, THREAD);
 901       assert(out != NULL, "Dump time allocation failure would have aborted VM");
 902       for (int i=0; i<length; i++) {
 903         out->at_put(i, vcflags_array->at(i));
 904       }
 905       _verifier_constraint_flags = out;
 906       size += out->size() * BytesPerWord;
 907       delete vcflags_array;
 908     }
 909 
 910     return size;
 911   }
 912   return 0;
 913 }
 914 
 915 void SharedDictionaryEntry::check_verification_constraints(InstanceKlass* klass, TRAPS) {
 916   Array<Symbol*>* vc_array = (Array<Symbol*>*)_verifier_constraints;
 917   Array<char>* vcflags_array = (Array<char>*)_verifier_constraint_flags;
 918 
 919   if (vc_array != NULL) {
 920     int length = vc_array->length();
 921     for (int i=0; i<length; i+=2) {
 922       Symbol* name      = vc_array->at(i);
 923       Symbol* from_name = vc_array->at(i+1);
 924       char c = vcflags_array->at(i/2);
 925 
 926       bool from_field_is_protected = (c & FROM_FIELD_IS_PROTECTED) ? true : false;
 927       bool from_is_array           = (c & FROM_IS_ARRAY)           ? true : false;
 928       bool from_is_object          = (c & FROM_IS_OBJECT)          ? true : false;
 929 
 930       bool ok = VerificationType::resolve_and_check_assignability(klass, name,
 931          from_name, from_field_is_protected, from_is_array, from_is_object, CHECK);
 932       if (!ok) {
 933         ResourceMark rm(THREAD);
 934         stringStream ss;
 935 
 936         ss.print_cr("Bad type on operand stack");
 937         ss.print_cr("Exception Details:");
 938         ss.print_cr("  Location:\n    %s", klass->name()->as_C_string());
 939         ss.print_cr("  Reason:\n    Type '%s' is not assignable to '%s'",
 940                     from_name->as_quoted_ascii(), name->as_quoted_ascii());
 941         THROW_MSG(vmSymbols::java_lang_VerifyError(), ss.as_string());
 942       }
 943     }
 944   }
 945 }
 946 
 947 void SharedDictionaryEntry::metaspace_pointers_do(MetaspaceClosure* it) {
 948   it->push((Array<Symbol*>**)&_verifier_constraints);
 949   it->push((Array<char>**)&_verifier_constraint_flags);
 950 }
 951 
 952 bool SharedDictionary::add_non_builtin_klass(const Symbol* class_name,
 953                                              ClassLoaderData* loader_data,
 954                                              InstanceKlass* klass) {
 955 
 956   assert(DumpSharedSpaces, "supported only when dumping");
 957   assert(klass != NULL, "adding NULL klass");
 958   assert(klass->name() == class_name, "sanity check on name");
 959   assert(klass->shared_classpath_index() < 0,
 960          "the shared classpath index should not be set for shared class loaded by the custom loaders");
 961 
 962   // Add an entry for a non-builtin class.
 963   // For a shared class for custom class loaders, SystemDictionary::resolve_or_null will
 964   // not find this class, because is_builtin() is false.
 965   unsigned int hash = compute_hash(class_name);
 966   int index = hash_to_index(hash);
 967 
 968   for (SharedDictionaryEntry* entry = bucket(index);
 969                               entry != NULL;
 970                               entry = entry->next()) {
 971     if (entry->hash() == hash) {
 972       Klass* klass = (Klass*)entry->literal();
 973       if (klass->name() == class_name && klass->class_loader_data() == loader_data) {
 974         // There is already a class defined with the same name
 975         return false;
 976       }
 977     }
 978   }
 979 
 980   assert(Dictionary::entry_size() >= sizeof(SharedDictionaryEntry), "must be big enough");
 981   SharedDictionaryEntry* entry = (SharedDictionaryEntry*)new_entry(hash, klass);
 982   add_entry(index, entry);
 983 
 984   assert(entry->is_unregistered(), "sanity");
 985   assert(!entry->is_builtin(), "sanity");
 986   return true;
 987 }
 988 
 989 
 990 //-----------------
 991 // SharedDictionary
 992 //-----------------
 993 
 994 
 995 Klass* SharedDictionary::find_class_for_builtin_loader(const Symbol* name) const {
 996   SharedDictionaryEntry* entry = get_entry_for_builtin_loader(name);
 997   return entry != NULL ? entry->instance_klass() : (Klass*)NULL;
 998 }
 999 
1000 Klass* SharedDictionary::find_class_for_unregistered_loader(const Symbol* name,
1001                                                             int clsfile_size,
1002                                                             int clsfile_crc32) const {
1003 
1004   const SharedDictionaryEntry* entry = get_entry_for_unregistered_loader(name,
1005                                                                          clsfile_size,
1006                                                                          clsfile_crc32);
1007   return entry != NULL ? entry->instance_klass() : (Klass*)NULL;
1008 }
1009 
1010 void SharedDictionary::update_entry(Klass* klass, int id) {
1011   assert(DumpSharedSpaces, "supported only when dumping");
1012   Symbol* class_name = klass->name();
1013   unsigned int hash = compute_hash(class_name);
1014   int index = hash_to_index(hash);
1015 
1016   for (SharedDictionaryEntry* entry = bucket(index);
1017                               entry != NULL;
1018                               entry = entry->next()) {
1019     if (entry->hash() == hash && entry->literal() == klass) {
1020       entry->_id = id;
1021       return;
1022     }
1023   }
1024 
1025   ShouldNotReachHere();
1026 }
1027 
1028 SharedDictionaryEntry* SharedDictionary::get_entry_for_builtin_loader(const Symbol* class_name) const {
1029   assert(!DumpSharedSpaces, "supported only when at runtime");
1030   unsigned int hash = compute_hash(class_name);
1031   const int index = hash_to_index(hash);
1032 
1033   for (SharedDictionaryEntry* entry = bucket(index);
1034                               entry != NULL;
1035                               entry = entry->next()) {
1036     if (entry->hash() == hash && entry->equals(class_name)) {
1037       if (entry->is_builtin()) {
1038         return entry;
1039       }
1040     }
1041   }
1042   return NULL;
1043 }
1044 
1045 SharedDictionaryEntry* SharedDictionary::get_entry_for_unregistered_loader(const Symbol* class_name,
1046                                                                            int clsfile_size,
1047                                                                            int clsfile_crc32) const {
1048   assert(!DumpSharedSpaces, "supported only when at runtime");
1049   unsigned int hash = compute_hash(class_name);
1050   int index = hash_to_index(hash);
1051 
1052   for (SharedDictionaryEntry* entry = bucket(index);
1053                               entry != NULL;
1054                               entry = entry->next()) {
1055     if (entry->hash() == hash && entry->equals(class_name)) {
1056       if (entry->is_unregistered()) {
1057         if (clsfile_size == -1) {
1058           // We're called from class_exists_for_unregistered_loader. At run time, we want to
1059           // compute the CRC of a ClassFileStream only if there is an UNREGISTERED class
1060           // with the matching name.
1061           return entry;
1062         } else {
1063           // We're called from find_class_for_unregistered_loader
1064           if (entry->_clsfile_size && clsfile_crc32 == entry->_clsfile_crc32) {
1065             return entry;
1066           }
1067         }
1068 
1069         // There can be only 1 class with this name for unregistered loaders.
1070         return NULL;
1071       }
1072     }
1073   }
1074   return NULL;
1075 }