1 /*
   2  * Copyright (c) 1997, 2026, 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 "cds/aotClassLocation.hpp"
  26 #include "cds/cds_globals.hpp"
  27 #include "cds/cdsConfig.hpp"
  28 #include "cds/dynamicArchive.hpp"
  29 #include "cds/heapShared.hpp"
  30 #include "classfile/classFileStream.hpp"
  31 #include "classfile/classLoader.inline.hpp"
  32 #include "classfile/classLoaderData.inline.hpp"
  33 #include "classfile/classLoadInfo.hpp"
  34 #include "classfile/javaClasses.hpp"
  35 #include "classfile/klassFactory.hpp"
  36 #include "classfile/moduleEntry.hpp"
  37 #include "classfile/modules.hpp"
  38 #include "classfile/packageEntry.hpp"
  39 #include "classfile/symbolTable.hpp"
  40 #include "classfile/systemDictionary.hpp"
  41 #include "classfile/systemDictionaryShared.hpp"
  42 #include "classfile/vmClasses.hpp"
  43 #include "classfile/vmSymbols.hpp"
  44 #include "compiler/compileBroker.hpp"
  45 #include "cppstdlib/cstdlib.hpp"
  46 #include "interpreter/bytecodeStream.hpp"
  47 #include "interpreter/oopMapCache.hpp"
  48 #include "jimage.hpp"
  49 #include "jvm.h"
  50 #include "logging/log.hpp"
  51 #include "logging/logStream.hpp"
  52 #include "logging/logTag.hpp"
  53 #include "memory/allocation.inline.hpp"
  54 #include "memory/oopFactory.hpp"
  55 #include "memory/resourceArea.hpp"
  56 #include "memory/universe.hpp"
  57 #include "oops/instanceKlass.hpp"
  58 #include "oops/instanceRefKlass.hpp"
  59 #include "oops/klass.inline.hpp"
  60 #include "oops/method.inline.hpp"
  61 #include "oops/objArrayOop.inline.hpp"
  62 #include "oops/oop.inline.hpp"
  63 #include "oops/symbol.hpp"
  64 #include "prims/jvm_misc.hpp"
  65 #include "runtime/arguments.hpp"
  66 #include "runtime/handles.inline.hpp"
  67 #include "runtime/init.hpp"
  68 #include "runtime/interfaceSupport.inline.hpp"
  69 #include "runtime/java.hpp"
  70 #include "runtime/javaCalls.hpp"
  71 #include "runtime/os.hpp"
  72 #include "runtime/perfData.inline.hpp"
  73 #include "runtime/timer.hpp"
  74 #include "runtime/vm_version.hpp"
  75 #include "services/management.hpp"
  76 #include "services/threadService.hpp"
  77 #include "utilities/checkedCast.hpp"
  78 #include "utilities/classpathStream.hpp"
  79 #include "utilities/events.hpp"
  80 #include "utilities/macros.hpp"
  81 #include "utilities/ostream.hpp"
  82 #include "utilities/utf8.hpp"
  83 
  84 #include <ctype.h>
  85 
  86 // Entry point in java.dll for path canonicalization
  87 
  88 typedef int (*canonicalize_fn_t)(const char *orig, char *out, int len);
  89 
  90 static canonicalize_fn_t CanonicalizeEntry  = nullptr;
  91 
  92 // Entry points for jimage.dll for loading jimage file entries
  93 
  94 static JImageOpen_t                    JImageOpen             = nullptr;
  95 static JImageClose_t                   JImageClose            = nullptr;
  96 static JImageFindResource_t            JImageFindResource     = nullptr;
  97 static JImageGetResource_t             JImageGetResource      = nullptr;
  98 
  99 // JimageFile pointer, or null if exploded JDK build.
 100 static JImageFile*                     JImage_file            = nullptr;
 101 
 102 // Globals
 103 
 104 PerfCounter*    ClassLoader::_perf_accumulated_time = nullptr;
 105 PerfCounter*    ClassLoader::_perf_classes_inited = nullptr;
 106 PerfCounter*    ClassLoader::_perf_class_init_time = nullptr;
 107 PerfCounter*    ClassLoader::_perf_class_init_selftime = nullptr;
 108 PerfCounter*    ClassLoader::_perf_class_init_bytecodes_count = nullptr;
 109 PerfCounter*    ClassLoader::_perf_classes_verified = nullptr;
 110 PerfCounter*    ClassLoader::_perf_class_verify_time = nullptr;
 111 PerfCounter*    ClassLoader::_perf_class_verify_selftime = nullptr;
 112 PerfCounter*    ClassLoader::_perf_classes_linked = nullptr;
 113 PerfCounter*    ClassLoader::_perf_class_link_time = nullptr;
 114 PerfCounter*    ClassLoader::_perf_class_link_selftime = nullptr;
 115 PerfCounter*    ClassLoader::_perf_shared_classload_time = nullptr;
 116 PerfCounter*    ClassLoader::_perf_sys_classload_time = nullptr;
 117 PerfCounter*    ClassLoader::_perf_app_classload_time = nullptr;
 118 PerfCounter*    ClassLoader::_perf_app_classload_selftime = nullptr;
 119 PerfCounter*    ClassLoader::_perf_app_classload_count = nullptr;
 120 PerfCounter*    ClassLoader::_perf_define_appclasses = nullptr;
 121 PerfCounter*    ClassLoader::_perf_define_appclass_time = nullptr;
 122 PerfCounter*    ClassLoader::_perf_define_appclass_selftime = nullptr;
 123 PerfCounter*    ClassLoader::_perf_app_classfile_bytes_read = nullptr;
 124 PerfCounter*    ClassLoader::_perf_sys_classfile_bytes_read = nullptr;
 125 PerfCounter*    ClassLoader::_perf_preload_total_time = nullptr;
 126 PerfCounter*    ClassLoader::_perf_preload_time = nullptr;
 127 PerfCounter*    ClassLoader::_perf_prelink_time = nullptr;
 128 PerfCounter*    ClassLoader::_perf_preinit_time = nullptr;
 129 PerfCounter*    ClassLoader::_perf_preresolve_time = nullptr;
 130 PerfCounter*    ClassLoader::_perf_ik_link_methods_time = nullptr;
 131 PerfCounter*    ClassLoader::_perf_method_adapters_time = nullptr;
 132 PerfCounter*    ClassLoader::_perf_ik_link_methods_count = nullptr;
 133 PerfCounter*    ClassLoader::_perf_method_adapters_count = nullptr;
 134 PerfCounter*    ClassLoader::_unsafe_defineClassCallCounter = nullptr;
 135 PerfCounter*    ClassLoader::_perf_secondary_hash_time = nullptr;
 136 
 137 PerfTickCounters*    ClassLoader::_perf_resolve_indy_time = nullptr;
 138 PerfTickCounters*    ClassLoader::_perf_resolve_invokehandle_time = nullptr;
 139 PerfTickCounters*    ClassLoader::_perf_resolve_mh_time = nullptr;
 140 PerfTickCounters*    ClassLoader::_perf_resolve_mt_time = nullptr;
 141 
 142 PerfCounter*    ClassLoader::_perf_resolve_indy_count = nullptr;
 143 PerfCounter*    ClassLoader::_perf_resolve_invokehandle_count = nullptr;
 144 PerfCounter*    ClassLoader::_perf_resolve_mh_count = nullptr;
 145 PerfCounter*    ClassLoader::_perf_resolve_mt_count = nullptr;
 146 
 147 void ClassLoader::print_counters(outputStream *st) {
 148   st->print_cr("ClassLoader:");
 149   st->print_cr(   "  clinit:               " JLONG_FORMAT_W(6) "us / " JLONG_FORMAT " events",
 150                ClassLoader::class_init_time_ms(), ClassLoader::class_init_count());
 151   st->print_cr("  link methods:         " JLONG_FORMAT_W(6) "us / " JLONG_FORMAT " events",
 152                Management::ticks_to_us(_perf_ik_link_methods_time->get_value())   , _perf_ik_link_methods_count->get_value());
 153   st->print_cr("  method adapters:      " JLONG_FORMAT_W(6) "us / " JLONG_FORMAT " events",
 154                Management::ticks_to_us(_perf_method_adapters_time->get_value())   , _perf_method_adapters_count->get_value());
 155   if (CountBytecodes || CountBytecodesPerThread) {
 156     st->print_cr("; executed " JLONG_FORMAT " bytecodes", ClassLoader::class_init_bytecodes_count());
 157   }
 158   st->print_cr("  resolve...");
 159   st->print_cr("    invokedynamic:   " JLONG_FORMAT_W(6) "us (elapsed) " JLONG_FORMAT_W(6) "us (thread) / " JLONG_FORMAT_W(5) " events",
 160                _perf_resolve_indy_time->elapsed_counter_value_us(),
 161                _perf_resolve_indy_time->thread_counter_value_us(),
 162                _perf_resolve_indy_count->get_value());
 163   st->print_cr("    invokehandle:    " JLONG_FORMAT_W(6) "us (elapsed) " JLONG_FORMAT_W(6) "us (thread) / " JLONG_FORMAT_W(5) " events",
 164                _perf_resolve_invokehandle_time->elapsed_counter_value_us(),
 165                _perf_resolve_invokehandle_time->thread_counter_value_us(),
 166                _perf_resolve_invokehandle_count->get_value());
 167   st->print_cr("    CP_MethodHandle: " JLONG_FORMAT_W(6) "us (elapsed) " JLONG_FORMAT_W(6) "us (thread) / " JLONG_FORMAT_W(5) " events",
 168                _perf_resolve_mh_time->elapsed_counter_value_us(),
 169                _perf_resolve_mh_time->thread_counter_value_us(),
 170                _perf_resolve_mh_count->get_value());
 171   st->print_cr("    CP_MethodType:   " JLONG_FORMAT_W(6) "us (elapsed) " JLONG_FORMAT_W(6) "us (thread) / " JLONG_FORMAT_W(5) " events",
 172                _perf_resolve_mt_time->elapsed_counter_value_us(),
 173                _perf_resolve_mt_time->thread_counter_value_us(),
 174                _perf_resolve_mt_count->get_value());
 175 }
 176 
 177 GrowableArray<ModuleClassPathList*>* ClassLoader::_patch_mod_entries = nullptr;
 178 GrowableArray<ModuleClassPathList*>* ClassLoader::_exploded_entries = nullptr;
 179 ClassPathEntry* ClassLoader::_jrt_entry = nullptr;
 180 
 181 ClassPathEntry* volatile ClassLoader::_first_append_entry_list = nullptr;
 182 ClassPathEntry* volatile ClassLoader::_last_append_entry  = nullptr;
 183 
 184 // helper routines
 185 #if INCLUDE_CDS
 186 static bool string_starts_with(const char* str, const char* str_to_find) {
 187   size_t str_len = strlen(str);
 188   size_t str_to_find_len = strlen(str_to_find);
 189   if (str_to_find_len > str_len) {
 190     return false;
 191   }
 192   return (strncmp(str, str_to_find, str_to_find_len) == 0);
 193 }
 194 #endif
 195 
 196 static const char* get_jimage_version_string() {
 197   static char version_string[10] = "";
 198   if (version_string[0] == '\0') {
 199     jio_snprintf(version_string, sizeof(version_string), "%d.%d",
 200                  VM_Version::vm_major_version(), VM_Version::vm_minor_version());
 201   }
 202   return (const char*)version_string;
 203 }
 204 
 205 bool ClassLoader::string_ends_with(const char* str, const char* str_to_find) {
 206   size_t str_len = strlen(str);
 207   size_t str_to_find_len = strlen(str_to_find);
 208   if (str_to_find_len > str_len) {
 209     return false;
 210   }
 211   return (strncmp(str + (str_len - str_to_find_len), str_to_find, str_to_find_len) == 0);
 212 }
 213 
 214 // Used to obtain the package name from a fully qualified class name.
 215 Symbol* ClassLoader::package_from_class_name(const Symbol* name, bool* bad_class_name) {
 216   if (name == nullptr) {
 217     if (bad_class_name != nullptr) {
 218       *bad_class_name = true;
 219     }
 220     return nullptr;
 221   }
 222 
 223   int utf_len = name->utf8_length();
 224   const jbyte* base = (const jbyte*)name->base();
 225   const jbyte* start = base;
 226   const jbyte* end = UTF8::strrchr(start, utf_len, JVM_SIGNATURE_SLASH);
 227   if (end == nullptr) {
 228     return nullptr;
 229   }
 230   // Skip over '['s
 231   if (*start == JVM_SIGNATURE_ARRAY) {
 232     do {
 233       start++;
 234     } while (start < end && *start == JVM_SIGNATURE_ARRAY);
 235 
 236     // Fully qualified class names should not contain a 'L'.
 237     // Set bad_class_name to true to indicate that the package name
 238     // could not be obtained due to an error condition.
 239     // In this situation, is_same_class_package returns false.
 240     if (*start == JVM_SIGNATURE_CLASS) {
 241       if (bad_class_name != nullptr) {
 242         *bad_class_name = true;
 243       }
 244       return nullptr;
 245     }
 246   }
 247   // A class name could have just the slash character in the name,
 248   // in which case start > end
 249   if (start >= end) {
 250     // No package name
 251     if (bad_class_name != nullptr) {
 252       *bad_class_name = true;
 253     }
 254     return nullptr;
 255   }
 256   return SymbolTable::new_symbol(name, pointer_delta_as_int(start, base), pointer_delta_as_int(end, base));
 257 }
 258 
 259 // Given a fully qualified package name, find its defining package in the class loader's
 260 // package entry table.
 261 PackageEntry* ClassLoader::get_package_entry(Symbol* pkg_name, ClassLoaderData* loader_data) {
 262   if (pkg_name == nullptr) {
 263     return nullptr;
 264   }
 265   PackageEntryTable* pkgEntryTable = loader_data->packages();
 266   return pkgEntryTable->lookup_only(pkg_name);
 267 }
 268 
 269 const char* ClassPathEntry::copy_path(const char* path) {
 270   char* copy = NEW_C_HEAP_ARRAY(char, strlen(path)+1, mtClass);
 271   strcpy(copy, path);
 272   return copy;
 273 }
 274 
 275 ClassPathDirEntry::~ClassPathDirEntry() {
 276   FREE_C_HEAP_ARRAY(char, _dir);
 277 }
 278 
 279 ClassFileStream* ClassPathDirEntry::open_stream(JavaThread* current, const char* name) {
 280   // construct full path name
 281   assert((_dir != nullptr) && (name != nullptr), "sanity");
 282   size_t path_len = strlen(_dir) + strlen(name) + strlen(os::file_separator()) + 1;
 283   char* path = NEW_RESOURCE_ARRAY_IN_THREAD(current, char, path_len);
 284   int len = jio_snprintf(path, path_len, "%s%s%s", _dir, os::file_separator(), name);
 285   assert(len == (int)(path_len - 1), "sanity");
 286   // check if file exists
 287   struct stat st;
 288   if (os::stat(path, &st) == 0) {
 289     // found file, open it
 290     int file_handle = os::open(path, 0, 0);
 291     if (file_handle != -1) {
 292       // read contents into resource array
 293       u1* buffer = NEW_RESOURCE_ARRAY_IN_THREAD(current, u1, st.st_size);
 294       size_t num_read = ::read(file_handle, (char*) buffer, st.st_size);
 295       // close file
 296       ::close(file_handle);
 297       // construct ClassFileStream
 298       if (num_read == (size_t)st.st_size) {
 299         if (UsePerfData) {
 300           ClassLoader::perf_sys_classfile_bytes_read()->inc(num_read);
 301         }
 302 #ifdef ASSERT
 303         // Freeing path is a no-op here as buffer prevents it from being reclaimed. But we keep it for
 304         // debug builds so that we guard against use-after-free bugs.
 305         FREE_RESOURCE_ARRAY_IN_THREAD(current, char, path, path_len);
 306 #endif
 307         // We don't verify the length of the classfile stream fits in an int, but this is the
 308         // bootloader so we have control of this.
 309         // Resource allocated
 310         return new ClassFileStream(buffer,
 311                                    checked_cast<int>(st.st_size),
 312                                    _dir);
 313       }
 314     }
 315   }
 316   FREE_RESOURCE_ARRAY_IN_THREAD(current, char, path, path_len);
 317   return nullptr;
 318 }
 319 
 320 ClassPathZipEntry::ClassPathZipEntry(jzfile* zip, const char* zip_name) : ClassPathEntry() {
 321   _zip = zip;
 322   _zip_name = copy_path(zip_name);
 323 }
 324 
 325 ClassPathZipEntry::~ClassPathZipEntry() {
 326   ZipLibrary::close(_zip);
 327   FREE_C_HEAP_ARRAY(char, _zip_name);
 328 }
 329 
 330 bool ClassPathZipEntry::has_entry(JavaThread* current, const char* name) {
 331   ThreadToNativeFromVM ttn(current);
 332   // check whether zip archive contains name
 333   jint name_len;
 334   jint filesize;
 335   jzentry* entry = ZipLibrary::find_entry(_zip, name, &filesize, &name_len);
 336   if (entry == nullptr) {
 337     return false;
 338   } else {
 339      ZipLibrary::free_entry(_zip, entry);
 340     return true;
 341   }
 342 }
 343 
 344 u1* ClassPathZipEntry::open_entry(JavaThread* current, const char* name, jint* filesize, bool nul_terminate) {
 345   // enable call to C land
 346   ThreadToNativeFromVM ttn(current);
 347   // check whether zip archive contains name
 348   jint name_len;
 349   jzentry* entry = ZipLibrary::find_entry(_zip, name, filesize, &name_len);
 350   if (entry == nullptr) return nullptr;
 351   u1* buffer;
 352   char name_buf[128];
 353   char* filename;
 354   if (name_len < 128) {
 355     filename = name_buf;
 356   } else {
 357     filename = NEW_RESOURCE_ARRAY(char, name_len + 1);
 358   }
 359 
 360   // read contents into resource array
 361   size_t size = (uint32_t)(*filesize);
 362   if (nul_terminate) {
 363     if (sizeof(size) == sizeof(uint32_t) && size == UINT_MAX) {
 364       return nullptr; // 32-bit integer overflow will occur.
 365     }
 366     size++;
 367   }
 368   buffer = NEW_RESOURCE_ARRAY(u1, size);
 369   if (!ZipLibrary::read_entry(_zip, entry, buffer, filename)) {
 370     return nullptr;
 371   }
 372 
 373   // return result
 374   if (nul_terminate) {
 375     buffer[size - 1] = 0;
 376   }
 377   return buffer;
 378 }
 379 
 380 ClassFileStream* ClassPathZipEntry::open_stream(JavaThread* current, const char* name) {
 381   jint filesize;
 382   u1* buffer = open_entry(current, name, &filesize, false);
 383   if (buffer == nullptr) {
 384     return nullptr;
 385   }
 386   if (UsePerfData) {
 387     ClassLoader::perf_sys_classfile_bytes_read()->inc(filesize);
 388   }
 389   // Resource allocated
 390   return new ClassFileStream(buffer,
 391                              filesize,
 392                              _zip_name);
 393 }
 394 
 395 DEBUG_ONLY(ClassPathImageEntry* ClassPathImageEntry::_singleton = nullptr;)
 396 
 397 JImageFile* ClassPathImageEntry::jimage() const {
 398   return JImage_file;
 399 }
 400 
 401 JImageFile* ClassPathImageEntry::jimage_non_null() const {
 402   assert(ClassLoader::has_jrt_entry(), "must be");
 403   assert(jimage() != nullptr, "should have been opened by ClassLoader::lookup_vm_options "
 404                            "and remained throughout normal JVM lifetime");
 405   return jimage();
 406 }
 407 
 408 void ClassPathImageEntry::close_jimage() {
 409   if (jimage() != nullptr) {
 410     (*JImageClose)(jimage());
 411     JImage_file = nullptr;
 412   }
 413 }
 414 
 415 ClassPathImageEntry::ClassPathImageEntry(JImageFile* jimage, const char* name) :
 416   ClassPathEntry() {
 417   guarantee(jimage != nullptr, "jimage file is null");
 418   guarantee(name != nullptr, "jimage file name is null");
 419   assert(_singleton == nullptr, "VM supports only one jimage");
 420   DEBUG_ONLY(_singleton = this);
 421   size_t len = strlen(name) + 1;
 422   _name = copy_path(name);
 423 }
 424 
 425 ClassFileStream* ClassPathImageEntry::open_stream(JavaThread* current, const char* name) {
 426   return open_stream_for_loader(current, name, ClassLoaderData::the_null_class_loader_data());
 427 }
 428 
 429 // For a class in a named module, look it up in the jimage file using this syntax:
 430 //    /<module-name>/<package-name>/<base-class>
 431 //
 432 // Assumptions:
 433 //     1. There are no unnamed modules in the jimage file.
 434 //     2. A package is in at most one module in the jimage file.
 435 //
 436 ClassFileStream* ClassPathImageEntry::open_stream_for_loader(JavaThread* current, const char* name, ClassLoaderData* loader_data) {
 437   jlong size;
 438   JImageLocationRef location = 0;
 439 
 440   TempNewSymbol class_name = SymbolTable::new_symbol(name);
 441   TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
 442 
 443   if (pkg_name != nullptr) {
 444     if (!Universe::is_module_initialized()) {
 445       location = (*JImageFindResource)(jimage_non_null(), JAVA_BASE_NAME, get_jimage_version_string(), name, &size);
 446     } else {
 447       PackageEntry* package_entry = ClassLoader::get_package_entry(pkg_name, loader_data);
 448       if (package_entry != nullptr) {
 449         ResourceMark rm(current);
 450         // Get the module name
 451         ModuleEntry* module = package_entry->module();
 452         assert(module != nullptr, "Boot classLoader package missing module");
 453         assert(module->is_named(), "Boot classLoader package is in unnamed module");
 454         const char* module_name = module->name()->as_C_string();
 455         if (module_name != nullptr) {
 456           location = (*JImageFindResource)(jimage_non_null(), module_name, get_jimage_version_string(), name, &size);
 457         }
 458       }
 459     }
 460   }
 461 
 462   if (location != 0) {
 463     if (UsePerfData) {
 464       ClassLoader::perf_sys_classfile_bytes_read()->inc(size);
 465     }
 466     char* data = NEW_RESOURCE_ARRAY(char, size);
 467     (*JImageGetResource)(jimage_non_null(), location, data, size);
 468     // Resource allocated
 469     assert(this == (ClassPathImageEntry*)ClassLoader::get_jrt_entry(), "must be");
 470     return new ClassFileStream((u1*)data,
 471                                checked_cast<int>(size),
 472                                _name,
 473                                true); // from_boot_loader_modules_image
 474   }
 475 
 476   return nullptr;
 477 }
 478 
 479 JImageLocationRef ClassLoader::jimage_find_resource(JImageFile* jf,
 480                                                     const char* module_name,
 481                                                     const char* file_name,
 482                                                     jlong &size) {
 483   return ((*JImageFindResource)(jf, module_name, get_jimage_version_string(), file_name, &size));
 484 }
 485 
 486 bool ClassPathImageEntry::is_modules_image() const {
 487   assert(this == _singleton, "VM supports a single jimage");
 488   assert(this == (ClassPathImageEntry*)ClassLoader::get_jrt_entry(), "must be used for jrt entry");
 489   return true;
 490 }
 491 
 492 ModuleClassPathList::ModuleClassPathList(Symbol* module_name) {
 493   _module_name = module_name;
 494   _module_first_entry = nullptr;
 495   _module_last_entry = nullptr;
 496 }
 497 
 498 ModuleClassPathList::~ModuleClassPathList() {
 499   // Clean out each ClassPathEntry on list
 500   ClassPathEntry* e = _module_first_entry;
 501   while (e != nullptr) {
 502     ClassPathEntry* next_entry = e->next();
 503     delete e;
 504     e = next_entry;
 505   }
 506 }
 507 
 508 void ModuleClassPathList::add_to_list(ClassPathEntry* new_entry) {
 509   if (new_entry != nullptr) {
 510     if (_module_last_entry == nullptr) {
 511       _module_first_entry = _module_last_entry = new_entry;
 512     } else {
 513       _module_last_entry->set_next(new_entry);
 514       _module_last_entry = new_entry;
 515     }
 516   }
 517 }
 518 
 519 void ClassLoader::trace_class_path(const char* msg, const char* name) {
 520   LogTarget(Info, class, path) lt;
 521   if (lt.is_enabled()) {
 522     LogStream ls(lt);
 523     if (msg) {
 524       ls.print("%s", msg);
 525     }
 526     if (name) {
 527       if (strlen(name) < 256) {
 528         ls.print("%s", name);
 529       } else {
 530         // For very long paths, we need to print each character separately,
 531         // as print_cr() has a length limit
 532         while (name[0] != '\0') {
 533           ls.print("%c", name[0]);
 534           name++;
 535         }
 536       }
 537     }
 538     ls.cr();
 539   }
 540 }
 541 
 542 void ClassLoader::setup_bootstrap_search_path(JavaThread* current) {
 543   const char* bootcp = Arguments::get_boot_class_path();
 544   assert(bootcp != nullptr, "Boot class path must not be nullptr");
 545   if (PrintSharedArchiveAndExit) {
 546     // Don't print bootcp - this is the bootcp of this current VM process, not necessarily
 547     // the same as the boot classpath of the shared archive.
 548   } else {
 549     trace_class_path("bootstrap loader class path=", bootcp);
 550   }
 551   setup_bootstrap_search_path_impl(current, bootcp);
 552 }
 553 
 554 void ClassLoader::close_jrt_image() {
 555   // Not applicable for exploded builds
 556   if (!ClassLoader::has_jrt_entry()) return;
 557   _jrt_entry->close_jimage();
 558 }
 559 
 560 // Construct the array of module/path pairs as specified to --patch-module
 561 // for the boot loader to search ahead of the jimage, if the class being
 562 // loaded is defined to a module that has been specified to --patch-module.
 563 void ClassLoader::setup_patch_mod_entries() {
 564   JavaThread* current = JavaThread::current();
 565   GrowableArray<ModulePatchPath*>* patch_mod_args = Arguments::get_patch_mod_prefix();
 566   int num_of_entries = patch_mod_args->length();
 567 
 568   // Set up the boot loader's _patch_mod_entries list
 569   _patch_mod_entries = new (mtModule) GrowableArray<ModuleClassPathList*>(num_of_entries, mtModule);
 570 
 571   for (int i = 0; i < num_of_entries; i++) {
 572     const char* module_name = (patch_mod_args->at(i))->module_name();
 573     Symbol* const module_sym = SymbolTable::new_symbol(module_name);
 574     assert(module_sym != nullptr, "Failed to obtain Symbol for module name");
 575     ModuleClassPathList* module_cpl = new ModuleClassPathList(module_sym);
 576 
 577     char* class_path = (patch_mod_args->at(i))->path_string();
 578     ResourceMark rm(current);
 579     ClasspathStream cp_stream(class_path);
 580 
 581     while (cp_stream.has_next()) {
 582       const char* path = cp_stream.get_next();
 583       struct stat st;
 584       if (os::stat(path, &st) == 0) {
 585         // File or directory found
 586         ClassPathEntry* new_entry = create_class_path_entry(current, path, &st);
 587         // If the path specification is valid, enter it into this module's list
 588         if (new_entry != nullptr) {
 589           module_cpl->add_to_list(new_entry);
 590         }
 591       }
 592     }
 593 
 594     // Record the module into the list of --patch-module entries only if
 595     // valid ClassPathEntrys have been created
 596     if (module_cpl->module_first_entry() != nullptr) {
 597       _patch_mod_entries->push(module_cpl);
 598     }
 599   }
 600 }
 601 
 602 // Determine whether the module has been patched via the command-line
 603 // option --patch-module
 604 bool ClassLoader::is_in_patch_mod_entries(Symbol* module_name) {
 605   if (_patch_mod_entries != nullptr && _patch_mod_entries->is_nonempty()) {
 606     int table_len = _patch_mod_entries->length();
 607     for (int i = 0; i < table_len; i++) {
 608       ModuleClassPathList* patch_mod = _patch_mod_entries->at(i);
 609       if (module_name->fast_compare(patch_mod->module_name()) == 0) {
 610         return true;
 611       }
 612     }
 613   }
 614   return false;
 615 }
 616 
 617 // Set up the _jrt_entry if present and boot append path
 618 void ClassLoader::setup_bootstrap_search_path_impl(JavaThread* current, const char *class_path) {
 619   ResourceMark rm(current);
 620   ClasspathStream cp_stream(class_path);
 621   bool set_base_piece = true;
 622 
 623 #if INCLUDE_CDS
 624   if (CDSConfig::is_dumping_archive()) {
 625     if (!Arguments::has_jimage()) {
 626       vm_exit_during_initialization("CDS is not supported in exploded JDK build", nullptr);
 627     }
 628   }
 629 #endif
 630 
 631   while (cp_stream.has_next()) {
 632     const char* path = cp_stream.get_next();
 633 
 634     if (set_base_piece) {
 635       // The first time through the bootstrap_search setup, it must be determined
 636       // what the base or core piece of the boot loader search is.  Either a java runtime
 637       // image is present or this is an exploded module build situation.
 638       assert(string_ends_with(path, MODULES_IMAGE_NAME) || string_ends_with(path, JAVA_BASE_NAME),
 639              "Incorrect boot loader search path, no java runtime image or " JAVA_BASE_NAME " exploded build");
 640       struct stat st;
 641       if (os::stat(path, &st) == 0) {
 642         // Directory found
 643         if (JImage_file != nullptr) {
 644           assert(Arguments::has_jimage(), "sanity check");
 645           const char* canonical_path = get_canonical_path(path, current);
 646           assert(canonical_path != nullptr, "canonical_path issue");
 647 
 648           _jrt_entry = new ClassPathImageEntry(JImage_file, canonical_path);
 649           assert(_jrt_entry != nullptr && _jrt_entry->is_modules_image(), "No java runtime image present");
 650           assert(_jrt_entry->jimage() != nullptr, "No java runtime image");
 651         } // else it's an exploded build.
 652       } else {
 653         // If path does not exist, exit
 654         vm_exit_during_initialization("Unable to establish the boot loader search path", path);
 655       }
 656       set_base_piece = false;
 657     } else {
 658       // Every entry on the boot class path after the initial base piece,
 659       // which is set by os::set_boot_path(), is considered an appended entry.
 660       update_class_path_entry_list(current, path);
 661     }
 662   }
 663 }
 664 
 665 // Gets the exploded path for the named module. The memory for the path
 666 // is allocated on the C heap if `c_heap` is true otherwise in the resource area.
 667 static const char* get_exploded_module_path(const char* module_name, bool c_heap) {
 668   const char *home = Arguments::get_java_home();
 669   const char file_sep = os::file_separator()[0];
 670   // 10 represents the length of "modules" + 2 file separators + \0
 671   size_t len = strlen(home) + strlen(module_name) + 10;
 672   char *path = c_heap ? NEW_C_HEAP_ARRAY(char, len, mtModule) : NEW_RESOURCE_ARRAY(char, len);
 673   jio_snprintf(path, len, "%s%cmodules%c%s", home, file_sep, file_sep, module_name);
 674   return path;
 675 }
 676 
 677 // During an exploded modules build, each module defined to the boot loader
 678 // will be added to the ClassLoader::_exploded_entries array.
 679 void ClassLoader::add_to_exploded_build_list(JavaThread* current, Symbol* module_sym) {
 680   assert(!ClassLoader::has_jrt_entry(), "Exploded build not applicable");
 681   assert(_exploded_entries != nullptr, "_exploded_entries was not initialized");
 682 
 683   // Find the module's symbol
 684   ResourceMark rm(current);
 685   const char *module_name = module_sym->as_C_string();
 686   const char *path = get_exploded_module_path(module_name, false);
 687 
 688   struct stat st;
 689   if (os::stat(path, &st) == 0) {
 690     // Directory found
 691     ClassPathEntry* new_entry = create_class_path_entry(current, path, &st);
 692 
 693     // If the path specification is valid, enter it into this module's list.
 694     // There is no need to check for duplicate modules in the exploded entry list,
 695     // since no two modules with the same name can be defined to the boot loader.
 696     // This is checked at module definition time in Modules::define_module.
 697     if (new_entry != nullptr) {
 698       ModuleClassPathList* module_cpl = new ModuleClassPathList(module_sym);
 699       module_cpl->add_to_list(new_entry);
 700       {
 701         MutexLocker ml(current, Module_lock);
 702         _exploded_entries->push(module_cpl);
 703       }
 704       log_info(class, load)("path: %s", path);
 705     }
 706   }
 707 }
 708 
 709 jzfile* ClassLoader::open_zip_file(const char* canonical_path, char** error_msg, JavaThread* thread) {
 710   // enable call to C land
 711   ThreadToNativeFromVM ttn(thread);
 712   HandleMark hm(thread);
 713   return ZipLibrary::open(canonical_path, error_msg);
 714 }
 715 
 716 ClassPathEntry* ClassLoader::create_class_path_entry(JavaThread* current,
 717                                                      const char *path, const struct stat* st) {
 718   ClassPathEntry* new_entry = nullptr;
 719   if ((st->st_mode & S_IFMT) == S_IFREG) {
 720     ResourceMark rm(current);
 721     // Regular file, should be a zip file
 722     // Canonicalized filename
 723     const char* canonical_path = get_canonical_path(path, current);
 724     if (canonical_path == nullptr) {
 725       return nullptr;
 726     }
 727     char* error_msg = nullptr;
 728     jzfile* zip = open_zip_file(canonical_path, &error_msg, current);
 729     if (zip != nullptr && error_msg == nullptr) {
 730       new_entry = new ClassPathZipEntry(zip, path);
 731     } else {
 732       return nullptr;
 733     }
 734     log_info(class, path)("opened: %s", path);
 735     log_info(class, load)("opened: %s", path);
 736   } else {
 737     // Directory
 738     new_entry = new ClassPathDirEntry(path);
 739     log_info(class, load)("path: %s", path);
 740   }
 741   return new_entry;
 742 }
 743 
 744 
 745 // Create a class path zip entry for a given path (return null if not found
 746 // or zip/JAR file cannot be opened)
 747 ClassPathZipEntry* ClassLoader::create_class_path_zip_entry(const char *path) {
 748   // check for a regular file
 749   struct stat st;
 750   if (os::stat(path, &st) == 0) {
 751     if ((st.st_mode & S_IFMT) == S_IFREG) {
 752       JavaThread* thread = JavaThread::current();
 753       ResourceMark rm(thread);
 754       const char* canonical_path = get_canonical_path(path, thread);
 755       if (canonical_path != nullptr) {
 756         char* error_msg = nullptr;
 757         jzfile* zip = open_zip_file(canonical_path, &error_msg, thread);
 758         if (zip != nullptr && error_msg == nullptr) {
 759           // create using canonical path
 760           return new ClassPathZipEntry(zip, canonical_path);
 761         }
 762       }
 763     }
 764   }
 765   return nullptr;
 766 }
 767 
 768 // The boot append entries are added with a lock, and read lock free.
 769 void ClassLoader::add_to_boot_append_entries(ClassPathEntry *new_entry) {
 770   if (new_entry != nullptr) {
 771     MutexLocker ml(Bootclasspath_lock, Mutex::_no_safepoint_check_flag);
 772     if (_last_append_entry == nullptr) {
 773       _last_append_entry = new_entry;
 774       assert(first_append_entry() == nullptr, "boot loader's append class path entry list not empty");
 775       AtomicAccess::release_store(&_first_append_entry_list, new_entry);
 776     } else {
 777       _last_append_entry->set_next(new_entry);
 778       _last_append_entry = new_entry;
 779     }
 780   }
 781 }
 782 
 783 // Returns true IFF the file/dir exists and the entry was successfully created.
 784 bool ClassLoader::update_class_path_entry_list(JavaThread* current, const char *path) {
 785   struct stat st;
 786   if (os::stat(path, &st) == 0) {
 787     // File or directory found
 788     ClassPathEntry* new_entry = nullptr;
 789     new_entry = create_class_path_entry(current, path, &st);
 790     if (new_entry == nullptr) {
 791       return false;
 792     }
 793 
 794     // Do not reorder the bootclasspath which would break get_system_package().
 795     // Add new entry to linked list
 796     add_to_boot_append_entries(new_entry);
 797     return true;
 798   } else {
 799     return false;
 800   }
 801 }
 802 
 803 static void print_module_entry_table(const GrowableArray<ModuleClassPathList*>* const module_list) {
 804   ResourceMark rm;
 805   int num_of_entries = module_list->length();
 806   for (int i = 0; i < num_of_entries; i++) {
 807     ClassPathEntry* e;
 808     ModuleClassPathList* mpl = module_list->at(i);
 809     tty->print("%s=", mpl->module_name()->as_C_string());
 810     e = mpl->module_first_entry();
 811     while (e != nullptr) {
 812       tty->print("%s", e->name());
 813       e = e->next();
 814       if (e != nullptr) {
 815         tty->print("%s", os::path_separator());
 816       }
 817     }
 818     tty->print(" ;");
 819   }
 820 }
 821 
 822 void ClassLoader::print_bootclasspath() {
 823   ClassPathEntry* e;
 824   tty->print("[bootclasspath= ");
 825 
 826   // Print --patch-module module/path specifications first
 827   if (_patch_mod_entries != nullptr) {
 828     print_module_entry_table(_patch_mod_entries);
 829   }
 830 
 831   // [jimage | exploded modules build]
 832   if (has_jrt_entry()) {
 833     // Print the location of the java runtime image
 834     tty->print("%s ;", _jrt_entry->name());
 835   } else {
 836     // Print exploded module build path specifications
 837     if (_exploded_entries != nullptr) {
 838       print_module_entry_table(_exploded_entries);
 839     }
 840   }
 841 
 842   // appended entries
 843   e = first_append_entry();
 844   while (e != nullptr) {
 845     tty->print("%s ;", e->name());
 846     e = e->next();
 847   }
 848   tty->print_cr("]");
 849 }
 850 
 851 void* ClassLoader::dll_lookup(void* lib, const char* name, const char* path) {
 852   void* func = os::dll_lookup(lib, name);
 853   if (func == nullptr) {
 854     char msg[256] = "";
 855     jio_snprintf(msg, sizeof(msg), "Could not resolve \"%s\"", name);
 856     vm_exit_during_initialization(msg, path);
 857   }
 858   return func;
 859 }
 860 
 861 void ClassLoader::load_java_library() {
 862   assert(CanonicalizeEntry == nullptr, "should not load java library twice");
 863   if (is_vm_statically_linked()) {
 864     CanonicalizeEntry = CAST_TO_FN_PTR(canonicalize_fn_t, os::lookup_function("JDK_Canonicalize"));
 865     assert(CanonicalizeEntry != nullptr, "could not lookup JDK_Canonicalize");
 866     return;
 867   }
 868 
 869   void *javalib_handle = os::native_java_library();
 870   if (javalib_handle == nullptr) {
 871     vm_exit_during_initialization("Unable to load java library", nullptr);
 872   }
 873 
 874   CanonicalizeEntry = CAST_TO_FN_PTR(canonicalize_fn_t, dll_lookup(javalib_handle, "JDK_Canonicalize", nullptr));
 875   assert(CanonicalizeEntry != nullptr, "could not lookup JDK_Canonicalize in java library");
 876 }
 877 
 878 void ClassLoader::load_jimage_library() {
 879   assert(JImageOpen == nullptr, "should not load jimage library twice");
 880 
 881   if (is_vm_statically_linked()) {
 882       JImageOpen = CAST_TO_FN_PTR(JImageOpen_t, os::lookup_function("JIMAGE_Open"));
 883       JImageClose = CAST_TO_FN_PTR(JImageClose_t, os::lookup_function("JIMAGE_Close"));
 884       JImageFindResource = CAST_TO_FN_PTR(JImageFindResource_t, os::lookup_function("JIMAGE_FindResource"));
 885       JImageGetResource = CAST_TO_FN_PTR(JImageGetResource_t, os::lookup_function("JIMAGE_GetResource"));
 886       assert(JImageOpen != nullptr && JImageClose != nullptr &&
 887             JImageFindResource != nullptr && JImageGetResource != nullptr,
 888             "could not lookup all jimage library functions");
 889       return;
 890     }
 891 
 892   char path[JVM_MAXPATHLEN];
 893   char ebuf[1024];
 894   void* handle = nullptr;
 895   if (os::dll_locate_lib(path, sizeof(path), Arguments::get_dll_dir(), "jimage")) {
 896     handle = os::dll_load(path, ebuf, sizeof ebuf);
 897   }
 898   if (handle == nullptr) {
 899     vm_exit_during_initialization("Unable to load jimage library", path);
 900   }
 901 
 902   JImageOpen = CAST_TO_FN_PTR(JImageOpen_t, dll_lookup(handle, "JIMAGE_Open", path));
 903   JImageClose = CAST_TO_FN_PTR(JImageClose_t, dll_lookup(handle, "JIMAGE_Close", path));
 904   JImageFindResource = CAST_TO_FN_PTR(JImageFindResource_t, dll_lookup(handle, "JIMAGE_FindResource", path));
 905   JImageGetResource = CAST_TO_FN_PTR(JImageGetResource_t, dll_lookup(handle, "JIMAGE_GetResource", path));
 906   assert(JImageOpen != nullptr && JImageClose != nullptr &&
 907         JImageFindResource != nullptr && JImageGetResource != nullptr,
 908         "could not lookup all jimage library functions in jimage library");
 909 }
 910 
 911 int ClassLoader::crc32(int crc, const char* buf, int len) {
 912   return ZipLibrary::crc32(crc, (const jbyte*)buf, len);
 913 }
 914 
 915 oop ClassLoader::get_system_package(const char* name, TRAPS) {
 916   // Look up the name in the boot loader's package entry table.
 917   if (name != nullptr) {
 918     TempNewSymbol package_sym = SymbolTable::new_symbol(name);
 919     // Look for the package entry in the boot loader's package entry table.
 920     PackageEntry* package =
 921       ClassLoaderData::the_null_class_loader_data()->packages()->lookup_only(package_sym);
 922 
 923     // Return null if package does not exist or if no classes in that package
 924     // have been loaded.
 925     if (package != nullptr && package->has_loaded_class()) {
 926       ModuleEntry* module = package->module();
 927       if (module->location() != nullptr) {
 928         ResourceMark rm(THREAD);
 929         Handle ml = java_lang_String::create_from_str(
 930           module->location()->as_C_string(), THREAD);
 931         return ml();
 932       }
 933       // Return entry on boot loader class path.
 934       Handle cph = java_lang_String::create_from_str(
 935         ClassLoader::classpath_entry(package->classpath_index())->name(), THREAD);
 936       return cph();
 937     }
 938   }
 939   return nullptr;
 940 }
 941 
 942 objArrayOop ClassLoader::get_system_packages(TRAPS) {
 943   ResourceMark rm(THREAD);
 944   // List of pointers to PackageEntrys that have loaded classes.
 945   PackageEntryTable* pe_table =
 946       ClassLoaderData::the_null_class_loader_data()->packages();
 947   GrowableArray<PackageEntry*>* loaded_class_pkgs = pe_table->get_system_packages();
 948 
 949   // Allocate objArray and fill with java.lang.String
 950   objArrayOop r = oopFactory::new_objArray(vmClasses::String_klass(),
 951                                            loaded_class_pkgs->length(), CHECK_NULL);
 952   objArrayHandle result(THREAD, r);
 953   for (int x = 0; x < loaded_class_pkgs->length(); x++) {
 954     PackageEntry* package_entry = loaded_class_pkgs->at(x);
 955     Handle str = java_lang_String::create_from_symbol(package_entry->name(), CHECK_NULL);
 956     result->obj_at_put(x, str());
 957   }
 958   return result();
 959 }
 960 
 961 // caller needs ResourceMark
 962 const char* ClassLoader::file_name_for_class_name(const char* class_name,
 963                                                   int class_name_len) {
 964   assert(class_name != nullptr, "invariant");
 965   assert((int)strlen(class_name) == class_name_len, "invariant");
 966 
 967   static const char class_suffix[] = ".class";
 968   size_t class_suffix_len = sizeof(class_suffix);
 969 
 970   char* const file_name = NEW_RESOURCE_ARRAY(char,
 971                                              class_name_len +
 972                                              class_suffix_len); // includes term null
 973 
 974   strncpy(file_name, class_name, class_name_len);
 975   strncpy(&file_name[class_name_len], class_suffix, class_suffix_len);
 976 
 977   return file_name;
 978 }
 979 
 980 static ClassPathEntry* find_first_module_cpe(ModuleEntry* mod_entry,
 981                                              const GrowableArray<ModuleClassPathList*>* const module_list) {
 982   int num_of_entries = module_list->length();
 983   const Symbol* class_module_name = mod_entry->name();
 984 
 985   // Loop through all the modules in either the patch-module or exploded entries looking for module
 986   for (int i = 0; i < num_of_entries; i++) {
 987     ModuleClassPathList* module_cpl = module_list->at(i);
 988     Symbol* module_cpl_name = module_cpl->module_name();
 989 
 990     if (module_cpl_name->fast_compare(class_module_name) == 0) {
 991       // Class' module has been located.
 992       return module_cpl->module_first_entry();
 993     }
 994   }
 995   return nullptr;
 996 }
 997 
 998 
 999 // Search the module list for the class file stream based on the file name and java package
1000 ClassFileStream* ClassLoader::search_module_entries(JavaThread* current,
1001                                                     const GrowableArray<ModuleClassPathList*>* const module_list,
1002                                                     PackageEntry* pkg_entry, // Java package entry derived from the class name
1003                                                     const char* const file_name) {
1004   ClassFileStream* stream = nullptr;
1005 
1006   // Find the defining module in the boot loader's module entry table
1007   ModuleEntry* mod_entry = (pkg_entry != nullptr) ? pkg_entry->module() : nullptr;
1008 
1009   // If the module system has not defined java.base yet, then
1010   // classes loaded are assumed to be defined to java.base.
1011   // When java.base is eventually defined by the module system,
1012   // all packages of classes that have been previously loaded
1013   // are verified in ModuleEntryTable::verify_javabase_packages().
1014   if (!Universe::is_module_initialized() &&
1015       !ModuleEntryTable::javabase_defined() &&
1016       mod_entry == nullptr) {
1017     mod_entry = ModuleEntryTable::javabase_moduleEntry();
1018   }
1019 
1020   // The module must be a named module
1021   ClassPathEntry* e = nullptr;
1022   if (mod_entry != nullptr && mod_entry->is_named()) {
1023     if (module_list == _exploded_entries) {
1024       // The exploded build entries can be added to at any time so a lock is
1025       // needed when searching them.
1026       assert(!ClassLoader::has_jrt_entry(), "Must be exploded build");
1027       MutexLocker ml(current, Module_lock);
1028       e = find_first_module_cpe(mod_entry, module_list);
1029     } else {
1030       e = find_first_module_cpe(mod_entry, module_list);
1031     }
1032   }
1033 
1034   // Try to load the class from the module's ClassPathEntry list.
1035   while (e != nullptr) {
1036     stream = e->open_stream(current, file_name);
1037     // No context.check is required since CDS is not supported
1038     // for an exploded modules build or if --patch-module is specified.
1039     if (nullptr != stream) {
1040       return stream;
1041     }
1042     e = e->next();
1043   }
1044   // If the module was located, break out even if the class was not
1045   // located successfully from that module's ClassPathEntry list.
1046   // There will not be another valid entry for that module.
1047   return nullptr;
1048 }
1049 
1050 // Called by the boot classloader to load classes
1051 InstanceKlass* ClassLoader::load_class(Symbol* name, PackageEntry* pkg_entry, bool search_append_only, TRAPS) {
1052   assert(name != nullptr, "invariant");
1053 
1054   ResourceMark rm(THREAD);
1055   HandleMark hm(THREAD);
1056 
1057   const char* const class_name = name->as_C_string();
1058 
1059   EventMarkClassLoading m("Loading class %s", class_name);
1060 
1061   const char* const file_name = file_name_for_class_name(class_name,
1062                                                          name->utf8_length());
1063   assert(file_name != nullptr, "invariant");
1064 
1065   // Lookup stream for parsing .class file
1066   ClassFileStream* stream = nullptr;
1067   s2 classpath_index = 0;
1068   ClassPathEntry* e = nullptr;
1069 
1070   // If search_append_only is true, boot loader visibility boundaries are
1071   // set to be _first_append_entry to the end. This includes:
1072   //   [-Xbootclasspath/a]; [jvmti appended entries]
1073   //
1074   // If search_append_only is false, boot loader visibility boundaries are
1075   // set to be the --patch-module entries plus the base piece. This includes:
1076   //   [--patch-module=<module>=<file>(<pathsep><file>)*]; [jimage | exploded module build]
1077   //
1078 
1079   // Load Attempt #1: --patch-module
1080   // Determine the class' defining module.  If it appears in the _patch_mod_entries,
1081   // attempt to load the class from those locations specific to the module.
1082   // Specifications to --patch-module can contain a partial number of classes
1083   // that are part of the overall module definition.  So if a particular class is not
1084   // found within its module specification, the search should continue to Load Attempt #2.
1085   // Note: The --patch-module entries are never searched if the boot loader's
1086   //       visibility boundary is limited to only searching the append entries.
1087   if (_patch_mod_entries != nullptr && !search_append_only) {
1088     assert(!CDSConfig::is_dumping_archive(), "CDS doesn't support --patch-module during dumping");
1089     stream = search_module_entries(THREAD, _patch_mod_entries, pkg_entry, file_name);
1090   }
1091 
1092   // Load Attempt #2: [jimage | exploded build]
1093   if (!search_append_only && (nullptr == stream)) {
1094     if (has_jrt_entry()) {
1095       e = _jrt_entry;
1096       stream = _jrt_entry->open_stream(THREAD, file_name);
1097     } else {
1098       // Exploded build - attempt to locate class in its defining module's location.
1099       assert(_exploded_entries != nullptr, "No exploded build entries present");
1100       assert(!CDSConfig::is_dumping_archive(), "CDS dumping doesn't support exploded build");
1101       stream = search_module_entries(THREAD, _exploded_entries, pkg_entry, file_name);
1102     }
1103   }
1104 
1105   // Load Attempt #3: [-Xbootclasspath/a]; [jvmti appended entries]
1106   if (search_append_only && (nullptr == stream)) {
1107     // For the boot loader append path search, the starting classpath_index
1108     // for the appended piece is always 1 to account for either the
1109     // _jrt_entry or the _exploded_entries.
1110     assert(classpath_index == 0, "The classpath_index has been incremented incorrectly");
1111     classpath_index = 1;
1112 
1113     e = first_append_entry();
1114     while (e != nullptr) {
1115       stream = e->open_stream(THREAD, file_name);
1116       if (nullptr != stream) {
1117         break;
1118       }
1119       e = e->next();
1120       ++classpath_index;
1121     }
1122   }
1123 
1124   if (nullptr == stream) {
1125     return nullptr;
1126   }
1127 
1128   ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
1129   Handle protection_domain;
1130   ClassLoadInfo cl_info(protection_domain);
1131 
1132   InstanceKlass* result = KlassFactory::create_from_stream(stream,
1133                                                            name,
1134                                                            loader_data,
1135                                                            cl_info,
1136                                                            CHECK_NULL);
1137   result->set_classpath_index(classpath_index);
1138   return result;
1139 }
1140 
1141 #if INCLUDE_CDS
1142 static const char* skip_uri_protocol(const char* source) {
1143   if (strncmp(source, "file:", 5) == 0) {
1144     // file: protocol path could start with file:/ or file:///
1145     // locate the char after all the forward slashes
1146     int offset = 5;
1147     while (*(source + offset) == '/') {
1148         offset++;
1149     }
1150     source += offset;
1151   // for non-windows platforms, move back one char as the path begins with a '/'
1152 #ifndef _WINDOWS
1153     source -= 1;
1154 #endif
1155   } else if (strncmp(source, "jrt:/", 5) == 0) {
1156     source += 5;
1157   }
1158   return source;
1159 }
1160 
1161 static char decode_percent_encoded(const char *str, size_t& index) {
1162   if (str[index] == '%'
1163       && isxdigit(str[index + 1])
1164       && isxdigit(str[index + 2])) {
1165     char hex[3];
1166     hex[0] = str[index + 1];
1167     hex[1] = str[index + 2];
1168     hex[2] = '\0';
1169     index += 2;
1170     return (char) strtol(hex, nullptr, 16);
1171   }
1172   return str[index];
1173 }
1174 
1175 char* ClassLoader::uri_to_path(const char* uri) {
1176   const size_t len = strlen(uri) + 1;
1177   char* path = NEW_RESOURCE_ARRAY(char, len);
1178 
1179   uri = skip_uri_protocol(uri);
1180 
1181   if (strncmp(uri, "//", 2) == 0) {
1182     // Skip the empty "authority" part
1183     uri += 2;
1184   }
1185 
1186 #ifdef _WINDOWS
1187   if (uri[0] == '/') {
1188     // Absolute path name on Windows does not begin with a slash
1189     uri += 1;
1190   }
1191 #endif
1192 
1193   size_t path_index = 0;
1194   for (size_t i = 0; i < strlen(uri); ++i) {
1195     char decoded = decode_percent_encoded(uri, i);
1196     path[path_index++] = decoded;
1197   }
1198   path[path_index] = '\0';
1199   return path;
1200 }
1201 
1202 // Record the shared classpath index and loader type for classes loaded
1203 // by the builtin loaders at dump time.
1204 void ClassLoader::record_result(JavaThread* current, InstanceKlass* ik,
1205                                 const ClassFileStream* stream, bool redefined) {
1206   assert(CDSConfig::is_dumping_archive(), "sanity");
1207   assert(stream != nullptr, "sanity");
1208 
1209   if (ik->is_hidden()) {
1210     record_hidden_class(ik);
1211     return;
1212   }
1213 
1214   oop loader = ik->class_loader();
1215   char* src = (char*)stream->source();
1216   if (src == nullptr) {
1217     ik->set_shared_classpath_index(-1); // unsupported location
1218     return;
1219   }
1220 
1221   if (!SystemDictionaryShared::is_builtin_loader(ik->class_loader_data())) {
1222     // A class loaded by a user-defined classloader.
1223     assert(ik->shared_classpath_index() < 0, "not assigned yet");
1224     ik->set_shared_classpath_index(UNREGISTERED_INDEX);
1225     SystemDictionaryShared::set_shared_class_misc_info(ik, (ClassFileStream*)stream);
1226     return;
1227   }
1228 
1229   assert(has_jrt_entry(), "CDS dumping does not support exploded JDK build");
1230 
1231   ResourceMark rm(current);
1232   int classpath_index = -1;
1233   bool found_invalid = false;
1234 
1235   PackageEntry* pkg_entry = ik->package();
1236 
1237   if (!AOTClassLocationConfig::dumptime_is_ready()) {
1238     // The shared path table is set up after module system initialization.
1239     // The path table contains no entry before that. Any classes loaded prior
1240     // to the setup of the shared path table must be from the modules image.
1241     assert(stream->from_boot_loader_modules_image(), "stream must be loaded by boot loader from modules image");
1242     classpath_index = 0;
1243   } else {
1244     // Save the path from the file: protocol or the module name from the jrt: protocol
1245     // if no protocol prefix is found, path is the same as stream->source(). This path
1246     // must be valid since the class has been successfully parsed.
1247     const char* path = ClassLoader::uri_to_path(src);
1248     assert(path != nullptr, "sanity");
1249     AOTClassLocationConfig::dumptime_iterate([&] (AOTClassLocation* cl) {
1250       int i = cl->index();
1251       // for index 0 and the stream->source() is the modules image or has the jrt: protocol.
1252       // The class must be from the runtime modules image.
1253       if (cl->is_modules_image() && (stream->from_boot_loader_modules_image() || string_starts_with(src, "jrt:"))) {
1254         classpath_index = i;
1255       } else if (os::same_files(cl->path(), path)) {
1256         // If the path (from the class stream source) is the same as the shared
1257         // class or module path, then we have a match.
1258         // src may come from the App/Platform class loaders, which would canonicalize
1259         // the file name. We cannot use strcmp to check for equality against cs->path().
1260         // We must use os::same_files (which is faster than canonicalizing cs->path()).
1261 
1262         // null pkg_entry and pkg_entry in an unnamed module implies the class
1263         // is from the -cp or boot loader append path which consists of -Xbootclasspath/a
1264         // and jvmti appended entries.
1265         if ((pkg_entry == nullptr) || (pkg_entry->in_unnamed_module())) {
1266           // Ensure the index is within the -cp range before assigning
1267           // to the classpath_index.
1268           if (SystemDictionary::is_system_class_loader(loader) && cl->from_app_classpath()) {
1269             classpath_index = i;
1270           } else {
1271             if (cl->from_boot_classpath()) {
1272               if (loader != nullptr) {
1273                 // Probably loaded by jdk/internal/loader/ClassLoaders$BootClassLoader. Don't archive
1274                 // such classes.
1275                 found_invalid = true;
1276               } else {
1277                 classpath_index = i;
1278               }
1279             }
1280           }
1281         } else {
1282           // A class from a named module from the --module-path. Ensure the index is
1283           // within the --module-path range before assigning to the classpath_index.
1284           if ((pkg_entry != nullptr) && !(pkg_entry->in_unnamed_module()) && cl->from_module_path()) {
1285             classpath_index = i;
1286           }
1287         }
1288       }
1289       if (classpath_index >= 0 || found_invalid) {
1290         return false; // Break the AOTClassLocationConfig::dumptime_iterate() loop.
1291       } else {
1292         return true; // Keep iterating
1293       }
1294     });
1295   }
1296 
1297   if (found_invalid) {
1298     assert(classpath_index == -1, "sanity");
1299   }
1300 
1301   const char* const class_name = ik->name()->as_C_string();
1302   const char* const file_name = file_name_for_class_name(class_name,
1303                                                          ik->name()->utf8_length());
1304   assert(file_name != nullptr, "invariant");
1305   record_result_for_builtin_loader(checked_cast<s2>(classpath_index), ik, redefined);
1306 }
1307 
1308 void ClassLoader::record_result_for_builtin_loader(s2 classpath_index, InstanceKlass* result, bool redefined) {
1309   assert(CDSConfig::is_dumping_archive(), "sanity");
1310 
1311   oop loader = result->class_loader();
1312   if (SystemDictionary::is_system_class_loader(loader)) {
1313     AOTClassLocationConfig::dumptime_set_has_app_classes();
1314   } else if (SystemDictionary::is_platform_class_loader(loader)) {
1315     AOTClassLocationConfig::dumptime_set_has_platform_classes();
1316   } else {
1317     precond(loader == nullptr);
1318   }
1319 
1320   if (CDSConfig::is_dumping_preimage_static_archive() || CDSConfig::is_dumping_dynamic_archive()) {
1321     if (!AOTClassLocationConfig::dumptime()->is_valid_classpath_index(classpath_index, result)) {
1322       classpath_index = -1;
1323     }
1324   }
1325 
1326   AOTClassLocationConfig::dumptime_update_max_used_index(classpath_index);
1327   result->set_shared_classpath_index(classpath_index);
1328 }
1329 
1330 void ClassLoader::record_hidden_class(InstanceKlass* ik) {
1331   assert(ik->is_hidden(), "must be");
1332 
1333   if (ik->defined_by_other_loaders()) {
1334     // We don't archive hidden classes for non-builtin loaders.
1335     return;
1336   }
1337 
1338   if (HeapShared::is_lambda_proxy_klass(ik)) {
1339     InstanceKlass* nest_host = ik->nest_host_not_null();
1340     ik->set_shared_classpath_index(nest_host->shared_classpath_index());
1341   } else if (HeapShared::is_lambda_form_klass(ik)) {
1342     ik->set_shared_classpath_index(0);
1343   } else {
1344     // Generated invoker classes.
1345     if (ik->defined_by_app_loader()) {
1346       ik->set_shared_classpath_index(AOTClassLocationConfig::dumptime()->app_cp_start_index());
1347     } else {
1348       ik->set_shared_classpath_index(0);
1349     }
1350   }
1351 }
1352 
1353 void ClassLoader::append_boot_classpath(ClassPathEntry* new_entry) {
1354   if (CDSConfig::is_using_archive()) {
1355     warning("Sharing is only supported for boot loader classes because bootstrap classpath has been appended");
1356     FileMapInfo::current_info()->set_has_platform_or_app_classes(false);
1357     if (DynamicArchive::is_mapped()) {
1358       FileMapInfo::dynamic_info()->set_has_platform_or_app_classes(false);
1359     }
1360   }
1361   add_to_boot_append_entries(new_entry);
1362 }
1363 #endif // INCLUDE_CDS
1364 
1365 // Initialize the class loader's access to methods in libzip.  Parse and
1366 // process the boot classpath into a list ClassPathEntry objects.  Once
1367 // this list has been created, it must not change order (see class PackageInfo)
1368 // it can be appended to and is by jvmti.
1369 
1370 void ClassLoader::initialize(TRAPS) {
1371   if (UsePerfData) {
1372     // jvmstat performance counters
1373     NEWPERFTICKCOUNTER(_perf_accumulated_time, SUN_CLS, "time");
1374     NEWPERFTICKCOUNTER(_perf_class_init_time, SUN_CLS, "classInitTime");
1375     NEWPERFTICKCOUNTER(_perf_class_init_selftime, SUN_CLS, "classInitTime.self");
1376     NEWPERFTICKCOUNTER(_perf_class_verify_time, SUN_CLS, "classVerifyTime");
1377     NEWPERFTICKCOUNTER(_perf_class_verify_selftime, SUN_CLS, "classVerifyTime.self");
1378     NEWPERFTICKCOUNTER(_perf_class_link_time, SUN_CLS, "classLinkedTime");
1379     NEWPERFTICKCOUNTER(_perf_class_link_selftime, SUN_CLS, "classLinkedTime.self");
1380     NEWPERFEVENTCOUNTER(_perf_classes_inited, SUN_CLS, "initializedClasses");
1381     NEWPERFEVENTCOUNTER(_perf_classes_linked, SUN_CLS, "linkedClasses");
1382     NEWPERFEVENTCOUNTER(_perf_classes_verified, SUN_CLS, "verifiedClasses");
1383     NEWPERFEVENTCOUNTER(_perf_class_init_bytecodes_count, SUN_CLS, "clinitBytecodesCount");
1384 
1385     NEWPERFTICKCOUNTER(_perf_shared_classload_time, SUN_CLS, "sharedClassLoadTime");
1386     NEWPERFTICKCOUNTER(_perf_sys_classload_time, SUN_CLS, "sysClassLoadTime");
1387     NEWPERFTICKCOUNTER(_perf_app_classload_time, SUN_CLS, "appClassLoadTime");
1388     NEWPERFTICKCOUNTER(_perf_app_classload_selftime, SUN_CLS, "appClassLoadTime.self");
1389     NEWPERFEVENTCOUNTER(_perf_app_classload_count, SUN_CLS, "appClassLoadCount");
1390     NEWPERFTICKCOUNTER(_perf_define_appclasses, SUN_CLS, "defineAppClasses");
1391     NEWPERFTICKCOUNTER(_perf_define_appclass_time, SUN_CLS, "defineAppClassTime");
1392     NEWPERFTICKCOUNTER(_perf_define_appclass_selftime, SUN_CLS, "defineAppClassTime.self");
1393     NEWPERFBYTECOUNTER(_perf_app_classfile_bytes_read, SUN_CLS, "appClassBytes");
1394     NEWPERFBYTECOUNTER(_perf_sys_classfile_bytes_read, SUN_CLS, "sysClassBytes");
1395     NEWPERFEVENTCOUNTER(_unsafe_defineClassCallCounter, SUN_CLS, "unsafeDefineClassCalls");
1396     NEWPERFTICKCOUNTER(_perf_secondary_hash_time, SUN_CLS, "secondarySuperHashTime");
1397 
1398     if (log_is_enabled(Info, perf, class, link) || log_is_enabled(Info, init)) {
1399       NEWPERFTICKCOUNTER(_perf_preload_total_time, SUN_CLS, "preloadTotalTime");
1400       NEWPERFTICKCOUNTER(_perf_preload_time, SUN_CLS, "preloadTime");
1401       NEWPERFTICKCOUNTER(_perf_prelink_time, SUN_CLS, "prelinkTime");
1402       NEWPERFTICKCOUNTER(_perf_preinit_time, SUN_CLS, "preinitTime");
1403       NEWPERFTICKCOUNTER(_perf_preresolve_time, SUN_CLS, "preresolveTime");
1404 
1405       NEWPERFTICKCOUNTER(_perf_ik_link_methods_time, SUN_CLS, "linkMethodsTime");
1406       NEWPERFTICKCOUNTER(_perf_method_adapters_time, SUN_CLS, "makeAdaptersTime");
1407       NEWPERFEVENTCOUNTER(_perf_ik_link_methods_count, SUN_CLS, "linkMethodsCount");
1408       NEWPERFEVENTCOUNTER(_perf_method_adapters_count, SUN_CLS, "makeAdaptersCount");
1409 
1410       NEWPERFTICKCOUNTERS(_perf_resolve_indy_time, SUN_CLS, "resolve_invokedynamic_time");
1411       NEWPERFTICKCOUNTERS(_perf_resolve_invokehandle_time, SUN_CLS, "resolve_invokehandle_time");
1412       NEWPERFTICKCOUNTERS(_perf_resolve_mh_time, SUN_CLS, "resolve_MethodHandle_time");
1413       NEWPERFTICKCOUNTERS(_perf_resolve_mt_time, SUN_CLS, "resolve_MethodType_time");
1414 
1415       NEWPERFEVENTCOUNTER(_perf_resolve_indy_count, SUN_CLS, "resolve_invokedynamic_count");
1416       NEWPERFEVENTCOUNTER(_perf_resolve_invokehandle_count, SUN_CLS, "resolve_invokehandle_count");
1417       NEWPERFEVENTCOUNTER(_perf_resolve_mh_count, SUN_CLS, "resolve_MethodHandle_count");
1418       NEWPERFEVENTCOUNTER(_perf_resolve_mt_count, SUN_CLS, "resolve_MethodType_count");
1419     }
1420   }
1421 
1422   // lookup java library entry points
1423   load_java_library();
1424   // jimage library entry points are loaded below, in lookup_vm_options
1425   setup_bootstrap_search_path(THREAD);
1426 }
1427 
1428 static char* lookup_vm_resource(JImageFile *jimage, const char *jimage_version, const char *path) {
1429   jlong size;
1430   JImageLocationRef location = (*JImageFindResource)(jimage, "java.base", jimage_version, path, &size);
1431   if (location == 0)
1432     return nullptr;
1433   char *val = NEW_C_HEAP_ARRAY(char, size+1, mtClass);
1434   (*JImageGetResource)(jimage, location, val, size);
1435   val[size] = '\0';
1436   return val;
1437 }
1438 
1439 // Lookup VM options embedded in the modules jimage file
1440 char* ClassLoader::lookup_vm_options() {
1441   jint error;
1442   char modules_path[JVM_MAXPATHLEN];
1443   const char* fileSep = os::file_separator();
1444 
1445   // Initialize jimage library entry points
1446   load_jimage_library();
1447 
1448   jio_snprintf(modules_path, JVM_MAXPATHLEN, "%s%slib%smodules", Arguments::get_java_home(), fileSep, fileSep);
1449   JImage_file =(*JImageOpen)(modules_path, &error);
1450   if (JImage_file == nullptr) {
1451     return nullptr;
1452   }
1453 
1454   const char *jimage_version = get_jimage_version_string();
1455   char *options = lookup_vm_resource(JImage_file, jimage_version, "jdk/internal/vm/options");
1456   return options;
1457 }
1458 
1459 bool ClassLoader::is_module_observable(const char* module_name) {
1460   assert(JImageOpen != nullptr, "jimage library should have been opened");
1461   if (JImage_file == nullptr) {
1462     struct stat st;
1463     const char *path = get_exploded_module_path(module_name, true);
1464     bool res = os::stat(path, &st) == 0;
1465     FREE_C_HEAP_ARRAY(char, path);
1466     return res;
1467   }
1468   jlong size;
1469   const char *jimage_version = get_jimage_version_string();
1470   return (*JImageFindResource)(JImage_file, module_name, jimage_version, "module-info.class", &size) != 0;
1471 }
1472 
1473 jlong ClassLoader::classloader_time_ms() {
1474   return UsePerfData ?
1475     Management::ticks_to_ms(_perf_accumulated_time->get_value()) : -1;
1476 }
1477 
1478 jlong ClassLoader::class_init_bytecodes_count() {
1479   return UsePerfData ? _perf_class_init_bytecodes_count->get_value() : -1;
1480 }
1481 
1482 jlong ClassLoader::class_init_count() {
1483   return UsePerfData ? _perf_classes_inited->get_value() : -1;
1484 }
1485 
1486 jlong ClassLoader::class_init_time_ms() {
1487   return UsePerfData ?
1488     Management::ticks_to_ms(_perf_class_init_time->get_value()) : -1;
1489 }
1490 
1491 jlong ClassLoader::class_verify_time_ms() {
1492   return UsePerfData ?
1493     Management::ticks_to_ms(_perf_class_verify_time->get_value()) : -1;
1494 }
1495 
1496 jlong ClassLoader::class_link_count() {
1497   return UsePerfData ? _perf_classes_linked->get_value() : -1;
1498 }
1499 
1500 jlong ClassLoader::class_link_time_ms() {
1501   return UsePerfData ?
1502     Management::ticks_to_ms(_perf_class_link_time->get_value()) : -1;
1503 }
1504 
1505 int ClassLoader::compute_Object_vtable() {
1506   // hardwired for JDK1.2 -- would need to duplicate class file parsing
1507   // code to determine actual value from file
1508   // Would be value '11' if finals were in vtable
1509   int JDK_1_2_Object_vtable_size = 5;
1510   return JDK_1_2_Object_vtable_size * vtableEntry::size();
1511 }
1512 
1513 
1514 void classLoader_init1() {
1515   EXCEPTION_MARK;
1516   ClassLoader::initialize(THREAD);
1517   if (HAS_PENDING_EXCEPTION) {
1518     vm_exit_during_initialization("ClassLoader::initialize() failed unexpectedly");
1519   }
1520 }
1521 
1522 // Complete the ClassPathEntry setup for the boot loader
1523 void ClassLoader::classLoader_init2(JavaThread* current) {
1524   // Setup the list of module/path pairs for --patch-module processing
1525   // This must be done after the SymbolTable is created in order
1526   // to use fast_compare on module names instead of a string compare.
1527   if (Arguments::get_patch_mod_prefix() != nullptr) {
1528     setup_patch_mod_entries();
1529   }
1530 
1531   // Create the ModuleEntry for java.base (must occur after setup_patch_mod_entries
1532   // to successfully determine if java.base has been patched)
1533   create_javabase();
1534 
1535   // Setup the initial java.base/path pair for the exploded build entries.
1536   // As more modules are defined during module system initialization, more
1537   // entries will be added to the exploded build array.
1538   if (!has_jrt_entry()) {
1539     assert(!CDSConfig::is_dumping_archive(), "not supported with exploded module builds");
1540     assert(!CDSConfig::is_using_archive(), "UsedSharedSpaces not supported with exploded module builds");
1541     // Set up the boot loader's _exploded_entries list.  Note that this gets
1542     // done before loading any classes, by the same thread that will
1543     // subsequently do the first class load. So, no lock is needed for this.
1544     assert(_exploded_entries == nullptr, "Should only get initialized once");
1545     _exploded_entries = new (mtModule)
1546       GrowableArray<ModuleClassPathList*>(EXPLODED_ENTRY_SIZE, mtModule);
1547     add_to_exploded_build_list(current, vmSymbols::java_base());
1548   }
1549 }
1550 
1551 char* ClassLoader::get_canonical_path(const char* orig, Thread* thread) {
1552   assert(orig != nullptr, "bad arguments");
1553   // caller needs to allocate ResourceMark for the following output buffer
1554   char* canonical_path = NEW_RESOURCE_ARRAY_IN_THREAD(thread, char, JVM_MAXPATHLEN);
1555   ResourceMark rm(thread);
1556   // os::native_path writes into orig_copy
1557   char* orig_copy = ResourceArea::strdup(thread, orig);
1558   if ((CanonicalizeEntry)(os::native_path(orig_copy), canonical_path, JVM_MAXPATHLEN) < 0) {
1559     return nullptr;
1560   }
1561   return canonical_path;
1562 }
1563 
1564 void ClassLoader::create_javabase() {
1565   JavaThread* current = JavaThread::current();
1566 
1567   // Create java.base's module entry for the boot
1568   // class loader prior to loading j.l.Object.
1569   ClassLoaderData* null_cld = ClassLoaderData::the_null_class_loader_data();
1570 
1571   // Get module entry table
1572   ModuleEntryTable* null_cld_modules = null_cld->modules();
1573   if (null_cld_modules == nullptr) {
1574     vm_exit_during_initialization("No ModuleEntryTable for the boot class loader");
1575   }
1576 
1577   {
1578     MutexLocker ml(current, Module_lock);
1579     if (ModuleEntryTable::javabase_moduleEntry() == nullptr) {  // may have been inited by CDS.
1580       ModuleEntry* jb_module = null_cld_modules->locked_create_entry(Handle(),
1581                                false, vmSymbols::java_base(), nullptr, nullptr, null_cld);
1582       if (jb_module == nullptr) {
1583         vm_exit_during_initialization("Unable to create ModuleEntry for " JAVA_BASE_NAME);
1584       }
1585       ModuleEntryTable::set_javabase_moduleEntry(jb_module);
1586     }
1587   }
1588 }
1589 
1590 // Please keep following two functions at end of this file. With them placed at top or in middle of the file,
1591 // they could get inlined by aggressive compiler, an unknown trick, see bug 6966589.
1592 void PerfClassTraceTime::initialize() {
1593   if (!UsePerfData) return;
1594 
1595   if (_eventp != nullptr) {
1596     // increment the event counter
1597     _eventp->inc();
1598   }
1599 
1600   // stop the current active thread-local timer to measure inclusive time
1601   _prev_active_event = -1;
1602   for (int i=0; i < EVENT_TYPE_COUNT; i++) {
1603      if (_timers[i].is_active()) {
1604        assert(_prev_active_event == -1, "should have only one active timer");
1605        _prev_active_event = i;
1606        _timers[i].stop();
1607      }
1608   }
1609 
1610   if (_recursion_counters == nullptr || (_recursion_counters[_event_type])++ == 0) {
1611     // start the inclusive timer if not recursively called
1612     _t.start();
1613   }
1614 
1615   // start thread-local timer of the given event type
1616    if (!_timers[_event_type].is_active()) {
1617     _timers[_event_type].start();
1618   }
1619 }
1620 
1621 PerfClassTraceTime::~PerfClassTraceTime() {
1622   if (!UsePerfData) return;
1623 
1624   // stop the thread-local timer as the event completes
1625   // and resume the thread-local timer of the event next on the stack
1626   _timers[_event_type].stop();
1627   jlong selftime = _timers[_event_type].ticks();
1628 
1629   if (_prev_active_event >= 0) {
1630     _timers[_prev_active_event].start();
1631   }
1632 
1633   if (_recursion_counters != nullptr && --(_recursion_counters[_event_type]) > 0) return;
1634 
1635   // increment the counters only on the leaf call
1636   _t.stop();
1637   _timep->inc(_t.ticks());
1638   if (_selftimep != nullptr) {
1639     _selftimep->inc(selftime);
1640   }
1641   // add all class loading related event selftime to the accumulated time counter
1642   ClassLoader::perf_accumulated_time()->inc(selftime);
1643 
1644   // reset the timer
1645   _timers[_event_type].reset();
1646 }