1 /*
   2  * Copyright (c) 1997, 2025, 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 "interpreter/bytecodeStream.hpp"
  46 #include "interpreter/oopMapCache.hpp"
  47 #include "jimage.hpp"
  48 #include "jvm.h"
  49 #include "logging/log.hpp"
  50 #include "logging/logStream.hpp"
  51 #include "logging/logTag.hpp"
  52 #include "memory/allocation.inline.hpp"
  53 #include "memory/oopFactory.hpp"
  54 #include "memory/resourceArea.hpp"
  55 #include "memory/universe.hpp"
  56 #include "oops/instanceKlass.hpp"
  57 #include "oops/instanceRefKlass.hpp"
  58 #include "oops/klass.inline.hpp"
  59 #include "oops/method.inline.hpp"
  60 #include "oops/objArrayOop.inline.hpp"
  61 #include "oops/oop.inline.hpp"
  62 #include "oops/symbol.hpp"
  63 #include "prims/jvm_misc.hpp"
  64 #include "runtime/arguments.hpp"
  65 #include "runtime/handles.inline.hpp"
  66 #include "runtime/init.hpp"
  67 #include "runtime/interfaceSupport.inline.hpp"
  68 #include "runtime/java.hpp"
  69 #include "runtime/javaCalls.hpp"
  70 #include "runtime/os.hpp"
  71 #include "runtime/perfData.hpp"
  72 #include "runtime/timer.hpp"
  73 #include "runtime/vm_version.hpp"
  74 #include "services/management.hpp"
  75 #include "services/threadService.hpp"
  76 #include "utilities/checkedCast.hpp"
  77 #include "utilities/classpathStream.hpp"
  78 #include "utilities/events.hpp"
  79 #include "utilities/macros.hpp"
  80 #include "utilities/ostream.hpp"
  81 #include "utilities/utf8.hpp"
  82 
  83 #include <ctype.h>
  84 #include <stdlib.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 // PreviewMode status to control preview behaviour. JImage_file is unusable
 103 // for normal lookup until (Preview_mode != PREVIEW_MODE_UNINITIALIZED).
 104 enum PreviewMode {
 105   PREVIEW_MODE_UNINITIALIZED = 0,
 106   PREVIEW_MODE_DEFAULT = 1,
 107   PREVIEW_MODE_ENABLE_PREVIEW = 2
 108 };
 109 static PreviewMode                     Preview_mode           = PREVIEW_MODE_UNINITIALIZED;
 110 
 111 // Globals
 112 
 113 PerfCounter*    ClassLoader::_perf_accumulated_time = nullptr;
 114 PerfCounter*    ClassLoader::_perf_classes_inited = nullptr;
 115 PerfCounter*    ClassLoader::_perf_class_init_time = nullptr;
 116 PerfCounter*    ClassLoader::_perf_class_init_selftime = nullptr;
 117 PerfCounter*    ClassLoader::_perf_classes_verified = nullptr;
 118 PerfCounter*    ClassLoader::_perf_class_verify_time = nullptr;
 119 PerfCounter*    ClassLoader::_perf_class_verify_selftime = nullptr;
 120 PerfCounter*    ClassLoader::_perf_classes_linked = nullptr;
 121 PerfCounter*    ClassLoader::_perf_class_link_time = nullptr;
 122 PerfCounter*    ClassLoader::_perf_class_link_selftime = nullptr;
 123 PerfCounter*    ClassLoader::_perf_shared_classload_time = nullptr;
 124 PerfCounter*    ClassLoader::_perf_sys_classload_time = nullptr;
 125 PerfCounter*    ClassLoader::_perf_app_classload_time = nullptr;
 126 PerfCounter*    ClassLoader::_perf_app_classload_selftime = nullptr;
 127 PerfCounter*    ClassLoader::_perf_app_classload_count = nullptr;
 128 PerfCounter*    ClassLoader::_perf_define_appclasses = nullptr;
 129 PerfCounter*    ClassLoader::_perf_define_appclass_time = nullptr;
 130 PerfCounter*    ClassLoader::_perf_define_appclass_selftime = nullptr;
 131 PerfCounter*    ClassLoader::_perf_app_classfile_bytes_read = nullptr;
 132 PerfCounter*    ClassLoader::_perf_sys_classfile_bytes_read = nullptr;
 133 PerfCounter*    ClassLoader::_perf_ik_link_methods_time = nullptr;
 134 PerfCounter*    ClassLoader::_perf_method_adapters_time = nullptr;
 135 PerfCounter*    ClassLoader::_perf_ik_link_methods_count = nullptr;
 136 PerfCounter*    ClassLoader::_perf_method_adapters_count = nullptr;
 137 PerfCounter*    ClassLoader::_unsafe_defineClassCallCounter = nullptr;
 138 PerfCounter*    ClassLoader::_perf_secondary_hash_time = nullptr;
 139 
 140 PerfCounter*    ClassLoader::_perf_resolve_indy_time = nullptr;
 141 PerfCounter*    ClassLoader::_perf_resolve_invokehandle_time = nullptr;
 142 PerfCounter*    ClassLoader::_perf_resolve_mh_time = nullptr;
 143 PerfCounter*    ClassLoader::_perf_resolve_mt_time = nullptr;
 144 
 145 PerfCounter*    ClassLoader::_perf_resolve_indy_count = nullptr;
 146 PerfCounter*    ClassLoader::_perf_resolve_invokehandle_count = nullptr;
 147 PerfCounter*    ClassLoader::_perf_resolve_mh_count = nullptr;
 148 PerfCounter*    ClassLoader::_perf_resolve_mt_count = nullptr;
 149 
 150 void ClassLoader::print_counters(outputStream *st) {
 151   st->print_cr("ClassLoader:");
 152   st->print_cr("  clinit:               " JLONG_FORMAT "ms / " JLONG_FORMAT " events", ClassLoader::class_init_time_ms(), ClassLoader::class_init_count());
 153   st->print_cr("  link methods:         " JLONG_FORMAT "ms / " JLONG_FORMAT " events", Management::ticks_to_ms(_perf_ik_link_methods_time->get_value())   , _perf_ik_link_methods_count->get_value());
 154   st->print_cr("  method adapters:      " JLONG_FORMAT "ms / " JLONG_FORMAT " events", Management::ticks_to_ms(_perf_method_adapters_time->get_value())   , _perf_method_adapters_count->get_value());
 155   st->print_cr("  resolve...");
 156   st->print_cr("    invokedynamic:   " JLONG_FORMAT "ms / " JLONG_FORMAT " events", Management::ticks_to_ms(_perf_resolve_indy_time->get_value())         , _perf_resolve_indy_count->get_value());
 157   st->print_cr("    invokehandle:    " JLONG_FORMAT "ms / " JLONG_FORMAT " events", Management::ticks_to_ms(_perf_resolve_invokehandle_time->get_value()) , _perf_resolve_invokehandle_count->get_value());
 158   st->print_cr("    CP_MethodHandle: " JLONG_FORMAT "ms / " JLONG_FORMAT " events", Management::ticks_to_ms(_perf_resolve_mh_time->get_value())           , _perf_resolve_mh_count->get_value());
 159   st->print_cr("    CP_MethodType:   " JLONG_FORMAT "ms / " JLONG_FORMAT " events", Management::ticks_to_ms(_perf_resolve_mt_time->get_value())           , _perf_resolve_mt_count->get_value());
 160   st->cr();
 161 }
 162 
 163 GrowableArray<ModuleClassPathList*>* ClassLoader::_patch_mod_entries = nullptr;
 164 GrowableArray<ModuleClassPathList*>* ClassLoader::_exploded_entries = nullptr;
 165 ClassPathImageEntry* ClassLoader::_jrt_entry = nullptr;
 166 
 167 ClassPathEntry* volatile ClassLoader::_first_append_entry_list = nullptr;
 168 ClassPathEntry* volatile ClassLoader::_last_append_entry  = nullptr;
 169 
 170 // helper routines
 171 #if INCLUDE_CDS
 172 static bool string_starts_with(const char* str, const char* str_to_find) {
 173   size_t str_len = strlen(str);
 174   size_t str_to_find_len = strlen(str_to_find);
 175   if (str_to_find_len > str_len) {
 176     return false;
 177   }
 178   return (strncmp(str, str_to_find, str_to_find_len) == 0);
 179 }
 180 #endif
 181 









 182 bool ClassLoader::string_ends_with(const char* str, const char* str_to_find) {
 183   size_t str_len = strlen(str);
 184   size_t str_to_find_len = strlen(str_to_find);
 185   if (str_to_find_len > str_len) {
 186     return false;
 187   }
 188   return (strncmp(str + (str_len - str_to_find_len), str_to_find, str_to_find_len) == 0);
 189 }
 190 
 191 // Used to obtain the package name from a fully qualified class name.
 192 Symbol* ClassLoader::package_from_class_name(const Symbol* name, bool* bad_class_name) {
 193   if (name == nullptr) {
 194     if (bad_class_name != nullptr) {
 195       *bad_class_name = true;
 196     }
 197     return nullptr;
 198   }
 199 
 200   int utf_len = name->utf8_length();
 201   const jbyte* base = (const jbyte*)name->base();
 202   const jbyte* start = base;
 203   const jbyte* end = UTF8::strrchr(start, utf_len, JVM_SIGNATURE_SLASH);
 204   if (end == nullptr) {
 205     return nullptr;
 206   }
 207   // Skip over '['s
 208   if (*start == JVM_SIGNATURE_ARRAY) {
 209     do {
 210       start++;
 211     } while (start < end && *start == JVM_SIGNATURE_ARRAY);
 212 
 213     // Fully qualified class names should not contain a 'L'.
 214     // Set bad_class_name to true to indicate that the package name
 215     // could not be obtained due to an error condition.
 216     // In this situation, is_same_class_package returns false.
 217     if (*start == JVM_SIGNATURE_CLASS) {
 218       if (bad_class_name != nullptr) {
 219         *bad_class_name = true;
 220       }
 221       return nullptr;
 222     }
 223   }
 224   // A class name could have just the slash character in the name,
 225   // in which case start > end
 226   if (start >= end) {
 227     // No package name
 228     if (bad_class_name != nullptr) {
 229       *bad_class_name = true;
 230     }
 231     return nullptr;
 232   }
 233   return SymbolTable::new_symbol(name, pointer_delta_as_int(start, base), pointer_delta_as_int(end, base));
 234 }
 235 
 236 // --------------------------------
 237 // The following jimage_xxx static functions encapsulate all JImage_file and Preview_mode access.
 238 // This is done to make it easy to reason about the JImage file state (exists vs initialized etc.).
 239 
 240 // Opens the named JImage file and sets the JImage file reference.
 241 // Returns true if opening the JImage file was successful (see also jimage_exists()).
 242 static bool jimage_open(const char* modules_path) {
 243   // Currently 'error' is not set to anything useful, so ignore it here.
 244   jint error;
 245   JImage_file = (*JImageOpen)(modules_path, &error);
 246   return JImage_file != nullptr;
 247 }
 248 
 249 // Closes and clears the JImage file reference (this will only be called during shutdown).
 250 static void jimage_close() {
 251   if (JImage_file != nullptr) {
 252     (*JImageClose)(JImage_file);
 253     JImage_file = nullptr;
 254   }
 255 }
 256 
 257 // Returns whether a JImage file was opened (but NOT whether it was initialized yet).
 258 static bool jimage_exists() {
 259   return JImage_file != nullptr;
 260 }
 261 
 262 // Returns the JImage file reference (which may or may not be initialized).
 263 static JImageFile* jimage_non_null() {
 264   assert(jimage_exists(), "should have been opened by ClassLoader::lookup_vm_options "
 265                           "and remained throughout normal JVM lifetime");
 266   return JImage_file;
 267 }
 268 
 269 // Returns true if jimage_init() has been called. Once the JImage file is initialized,
 270 // jimage_is_preview_enabled() can be called to correctly determine the access mode.
 271 static bool jimage_is_initialized() {
 272   return jimage_exists() && Preview_mode != PREVIEW_MODE_UNINITIALIZED;
 273 }
 274 
 275 // Returns the access mode for an initialized JImage file (reflects --enable-preview).
 276 static bool is_preview_enabled() {
 277   return Preview_mode == PREVIEW_MODE_ENABLE_PREVIEW;
 278 }
 279 
 280 // Looks up the location of a named JImage resource. This "raw" lookup function allows
 281 // the preview mode to be manually specified, so must not be accessible outside this
 282 // class. ClassPathImageEntry manages all calls for resources after startup is complete.
 283 static JImageLocationRef jimage_find_resource(const char* module_name,
 284                                               const char* file_name,
 285                                               bool is_preview,
 286                                               jlong *size) {
 287   return ((*JImageFindResource)(jimage_non_null(),
 288                                 module_name,
 289                                 file_name,
 290                                 is_preview,
 291                                 size));
 292 }
 293 // --------------------------------
 294 
 295 // Given a fully qualified package name, find its defining package in the class loader's
 296 // package entry table.
 297 PackageEntry* ClassLoader::get_package_entry(Symbol* pkg_name, ClassLoaderData* loader_data) {
 298   if (pkg_name == nullptr) {
 299     return nullptr;
 300   }
 301   PackageEntryTable* pkgEntryTable = loader_data->packages();
 302   return pkgEntryTable->lookup_only(pkg_name);
 303 }
 304 
 305 const char* ClassPathEntry::copy_path(const char* path) {
 306   char* copy = NEW_C_HEAP_ARRAY(char, strlen(path)+1, mtClass);
 307   strcpy(copy, path);
 308   return copy;
 309 }
 310 
 311 ClassPathDirEntry::~ClassPathDirEntry() {
 312   FREE_C_HEAP_ARRAY(char, _dir);
 313 }
 314 
 315 ClassFileStream* ClassPathDirEntry::open_stream(JavaThread* current, const char* name) {
 316   // construct full path name
 317   assert((_dir != nullptr) && (name != nullptr), "sanity");
 318   size_t path_len = strlen(_dir) + strlen(name) + strlen(os::file_separator()) + 1;
 319   char* path = NEW_RESOURCE_ARRAY_IN_THREAD(current, char, path_len);
 320   int len = jio_snprintf(path, path_len, "%s%s%s", _dir, os::file_separator(), name);
 321   assert(len == (int)(path_len - 1), "sanity");
 322   // check if file exists
 323   struct stat st;
 324   if (os::stat(path, &st) == 0) {
 325     // found file, open it
 326     int file_handle = os::open(path, 0, 0);
 327     if (file_handle != -1) {
 328       // read contents into resource array
 329       u1* buffer = NEW_RESOURCE_ARRAY_IN_THREAD(current, u1, st.st_size);
 330       size_t num_read = ::read(file_handle, (char*) buffer, st.st_size);
 331       // close file
 332       ::close(file_handle);
 333       // construct ClassFileStream
 334       if (num_read == (size_t)st.st_size) {
 335         if (UsePerfData) {
 336           ClassLoader::perf_sys_classfile_bytes_read()->inc(num_read);
 337         }
 338 #ifdef ASSERT
 339         // Freeing path is a no-op here as buffer prevents it from being reclaimed. But we keep it for
 340         // debug builds so that we guard against use-after-free bugs.
 341         FREE_RESOURCE_ARRAY_IN_THREAD(current, char, path, path_len);
 342 #endif
 343         // We don't verify the length of the classfile stream fits in an int, but this is the
 344         // bootloader so we have control of this.
 345         // Resource allocated
 346         return new ClassFileStream(buffer,
 347                                    checked_cast<int>(st.st_size),
 348                                    _dir);
 349       }
 350     }
 351   }
 352   FREE_RESOURCE_ARRAY_IN_THREAD(current, char, path, path_len);
 353   return nullptr;
 354 }
 355 
 356 ClassPathZipEntry::ClassPathZipEntry(jzfile* zip, const char* zip_name) : ClassPathEntry() {
 357   _zip = zip;
 358   _zip_name = copy_path(zip_name);
 359 }
 360 
 361 ClassPathZipEntry::~ClassPathZipEntry() {
 362   ZipLibrary::close(_zip);
 363   FREE_C_HEAP_ARRAY(char, _zip_name);
 364 }
 365 
 366 bool ClassPathZipEntry::has_entry(JavaThread* current, const char* name) {
 367   ThreadToNativeFromVM ttn(current);
 368   // check whether zip archive contains name
 369   jint name_len;
 370   jint filesize;
 371   jzentry* entry = ZipLibrary::find_entry(_zip, name, &filesize, &name_len);
 372   if (entry == nullptr) {
 373     return false;
 374   } else {
 375      ZipLibrary::free_entry(_zip, entry);
 376     return true;
 377   }
 378 }
 379 
 380 u1* ClassPathZipEntry::open_entry(JavaThread* current, const char* name, jint* filesize, bool nul_terminate) {
 381   // enable call to C land
 382   ThreadToNativeFromVM ttn(current);
 383   // check whether zip archive contains name
 384   jint name_len;
 385   jzentry* entry = ZipLibrary::find_entry(_zip, name, filesize, &name_len);
 386   if (entry == nullptr) return nullptr;
 387   u1* buffer;
 388   char name_buf[128];
 389   char* filename;
 390   if (name_len < 128) {
 391     filename = name_buf;
 392   } else {
 393     filename = NEW_RESOURCE_ARRAY(char, name_len + 1);
 394   }
 395 
 396   // read contents into resource array
 397   size_t size = (uint32_t)(*filesize);
 398   if (nul_terminate) {
 399     if (sizeof(size) == sizeof(uint32_t) && size == UINT_MAX) {
 400       return nullptr; // 32-bit integer overflow will occur.
 401     }
 402     size++;
 403   }
 404   buffer = NEW_RESOURCE_ARRAY(u1, size);
 405   if (!ZipLibrary::read_entry(_zip, entry, buffer, filename)) {
 406     return nullptr;
 407   }
 408 
 409   // return result
 410   if (nul_terminate) {
 411     buffer[size - 1] = 0;
 412   }
 413   return buffer;
 414 }
 415 
 416 ClassFileStream* ClassPathZipEntry::open_stream(JavaThread* current, const char* name) {
 417   jint filesize;
 418   u1* buffer = open_entry(current, name, &filesize, false);
 419   if (buffer == nullptr) {
 420     return nullptr;
 421   }
 422   if (UsePerfData) {
 423     ClassLoader::perf_sys_classfile_bytes_read()->inc(filesize);
 424   }
 425   // Resource allocated
 426   return new ClassFileStream(buffer,
 427                              filesize,
 428                              _zip_name);
 429 }
 430 
 431 DEBUG_ONLY(ClassPathImageEntry* ClassPathImageEntry::_singleton = nullptr;)
 432 











 433 void ClassPathImageEntry::close_jimage() {
 434   jimage_close();



 435 }
 436 
 437 ClassPathImageEntry::ClassPathImageEntry(const char* name) :
 438   ClassPathEntry() {
 439   guarantee(jimage_is_initialized(), "jimage is not initialized");
 440   guarantee(name != nullptr, "jimage file name is null");
 441 
 442   assert(_singleton == nullptr, "VM supports only one jimage");
 443   DEBUG_ONLY(_singleton = this);
 444   size_t len = strlen(name) + 1;
 445   _name = copy_path(name);
 446 }
 447 
 448 ClassFileStream* ClassPathImageEntry::open_stream(JavaThread* current, const char* name) {
 449   return open_stream_for_loader(current, name, ClassLoaderData::the_null_class_loader_data());
 450 }
 451 
 452 // For a class in a named module, look it up in the jimage file using this syntax:
 453 //    /<module-name>/<package-name>/<base-class>
 454 //
 455 // Assumptions:
 456 //     1. There are no unnamed modules in the jimage file.
 457 //     2. A package is in at most one module in the jimage file.
 458 //
 459 ClassFileStream* ClassPathImageEntry::open_stream_for_loader(JavaThread* current, const char* name, ClassLoaderData* loader_data) {
 460   const bool is_preview = is_preview_enabled();
 461 
 462   jlong size;
 463   JImageLocationRef location = 0;
 464 
 465   TempNewSymbol class_name = SymbolTable::new_symbol(name);
 466   TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
 467 
 468   if (pkg_name != nullptr) {
 469     if (!Universe::is_module_initialized()) {
 470       location = jimage_find_resource(JAVA_BASE_NAME, name, is_preview, &size);
 471     } else {
 472       PackageEntry* package_entry = ClassLoader::get_package_entry(pkg_name, loader_data);
 473       if (package_entry != nullptr) {
 474         ResourceMark rm(current);
 475         // Get the module name
 476         ModuleEntry* module = package_entry->module();
 477         assert(module != nullptr, "Boot classLoader package missing module");
 478         assert(module->is_named(), "Boot classLoader package is in unnamed module");
 479         const char* module_name = module->name()->as_C_string();
 480         if (module_name != nullptr) {
 481           location = jimage_find_resource(module_name, name, is_preview, &size);
 482         }
 483       }
 484     }
 485   }
 486 
 487   if (location != 0) {
 488     if (UsePerfData) {
 489       ClassLoader::perf_sys_classfile_bytes_read()->inc(size);
 490     }
 491     char* data = NEW_RESOURCE_ARRAY(char, size);
 492     (*JImageGetResource)(jimage_non_null(), location, data, size);
 493     // Resource allocated
 494     assert(this == ClassLoader::get_jrt_entry(), "must be");
 495     return new ClassFileStream((u1*)data,
 496                                checked_cast<int>(size),
 497                                _name,
 498                                true); // from_boot_loader_modules_image
 499   }
 500 
 501   return nullptr;
 502 }
 503 







 504 bool ClassPathImageEntry::is_modules_image() const {
 505   assert(this == _singleton, "VM supports a single jimage");
 506   assert(this == ClassLoader::get_jrt_entry(), "must be used for jrt entry");
 507   return true;
 508 }
 509 
 510 ModuleClassPathList::ModuleClassPathList(Symbol* module_name) {
 511   _module_name = module_name;
 512   _module_first_entry = nullptr;
 513   _module_last_entry = nullptr;
 514 }
 515 
 516 ModuleClassPathList::~ModuleClassPathList() {
 517   // Clean out each ClassPathEntry on list
 518   ClassPathEntry* e = _module_first_entry;
 519   while (e != nullptr) {
 520     ClassPathEntry* next_entry = e->next();
 521     delete e;
 522     e = next_entry;
 523   }
 524 }
 525 
 526 void ModuleClassPathList::add_to_list(ClassPathEntry* new_entry) {
 527   if (new_entry != nullptr) {
 528     if (_module_last_entry == nullptr) {
 529       _module_first_entry = _module_last_entry = new_entry;
 530     } else {
 531       _module_last_entry->set_next(new_entry);
 532       _module_last_entry = new_entry;
 533     }
 534   }
 535 }
 536 
 537 void ClassLoader::trace_class_path(const char* msg, const char* name) {
 538   LogTarget(Info, class, path) lt;
 539   if (lt.is_enabled()) {
 540     LogStream ls(lt);
 541     if (msg) {
 542       ls.print("%s", msg);
 543     }
 544     if (name) {
 545       if (strlen(name) < 256) {
 546         ls.print("%s", name);
 547       } else {
 548         // For very long paths, we need to print each character separately,
 549         // as print_cr() has a length limit
 550         while (name[0] != '\0') {
 551           ls.print("%c", name[0]);
 552           name++;
 553         }
 554       }
 555     }
 556     ls.cr();
 557   }
 558 }
 559 
 560 void ClassLoader::setup_bootstrap_search_path(JavaThread* current) {
 561   const char* bootcp = Arguments::get_boot_class_path();
 562   assert(bootcp != nullptr, "Boot class path must not be nullptr");
 563   if (PrintSharedArchiveAndExit) {
 564     // Don't print bootcp - this is the bootcp of this current VM process, not necessarily
 565     // the same as the boot classpath of the shared archive.
 566   } else {
 567     trace_class_path("bootstrap loader class path=", bootcp);
 568   }
 569   setup_bootstrap_search_path_impl(current, bootcp);
 570 }
 571 
 572 void ClassLoader::close_jrt_image() {
 573   // Not applicable for exploded builds
 574   if (!ClassLoader::has_jrt_entry()) return;
 575   _jrt_entry->close_jimage();
 576 }
 577 
 578 // Construct the array of module/path pairs as specified to --patch-module
 579 // for the boot loader to search ahead of the jimage, if the class being
 580 // loaded is defined to a module that has been specified to --patch-module.
 581 void ClassLoader::setup_patch_mod_entries() {
 582   JavaThread* current = JavaThread::current();
 583   GrowableArray<ModulePatchPath*>* patch_mod_args = Arguments::get_patch_mod_prefix();
 584   int num_of_entries = patch_mod_args->length();
 585 
 586   // Set up the boot loader's _patch_mod_entries list
 587   _patch_mod_entries = new (mtModule) GrowableArray<ModuleClassPathList*>(num_of_entries, mtModule);
 588 
 589   for (int i = 0; i < num_of_entries; i++) {
 590     const char* module_name = (patch_mod_args->at(i))->module_name();
 591     Symbol* const module_sym = SymbolTable::new_symbol(module_name);
 592     assert(module_sym != nullptr, "Failed to obtain Symbol for module name");
 593     ModuleClassPathList* module_cpl = new ModuleClassPathList(module_sym);
 594 
 595     char* class_path = (patch_mod_args->at(i))->path_string();
 596     ResourceMark rm(current);
 597     ClasspathStream cp_stream(class_path);
 598 
 599     while (cp_stream.has_next()) {
 600       const char* path = cp_stream.get_next();
 601       struct stat st;
 602       if (os::stat(path, &st) == 0) {
 603         // File or directory found
 604         ClassPathEntry* new_entry = create_class_path_entry(current, path, &st);
 605         // If the path specification is valid, enter it into this module's list
 606         if (new_entry != nullptr) {
 607           module_cpl->add_to_list(new_entry);
 608         }
 609       }
 610     }
 611 
 612     // Record the module into the list of --patch-module entries only if
 613     // valid ClassPathEntrys have been created
 614     if (module_cpl->module_first_entry() != nullptr) {
 615       _patch_mod_entries->push(module_cpl);
 616     }
 617   }
 618 }
 619 
 620 // Determine whether the module has been patched via the command-line
 621 // option --patch-module
 622 bool ClassLoader::is_in_patch_mod_entries(Symbol* module_name) {
 623   if (_patch_mod_entries != nullptr && _patch_mod_entries->is_nonempty()) {
 624     int table_len = _patch_mod_entries->length();
 625     for (int i = 0; i < table_len; i++) {
 626       ModuleClassPathList* patch_mod = _patch_mod_entries->at(i);
 627       if (module_name->fast_compare(patch_mod->module_name()) == 0) {
 628         return true;
 629       }
 630     }
 631   }
 632   return false;
 633 }
 634 
 635 // Set up the _jrt_entry if present and boot append path
 636 void ClassLoader::setup_bootstrap_search_path_impl(JavaThread* current, const char *class_path) {
 637   ResourceMark rm(current);
 638   ClasspathStream cp_stream(class_path);
 639   bool set_base_piece = true;
 640 
 641 #if INCLUDE_CDS
 642   if (CDSConfig::is_dumping_archive()) {
 643     if (!Arguments::has_jimage()) {
 644       vm_exit_during_initialization("CDS is not supported in exploded JDK build", nullptr);
 645     }
 646   }
 647 #endif
 648 
 649   while (cp_stream.has_next()) {
 650     const char* path = cp_stream.get_next();
 651 
 652     if (set_base_piece) {
 653       // The first time through the bootstrap_search setup, it must be determined
 654       // what the base or core piece of the boot loader search is.  Either a java runtime
 655       // image is present or this is an exploded module build situation.
 656       assert(string_ends_with(path, MODULES_IMAGE_NAME) || string_ends_with(path, JAVA_BASE_NAME),
 657              "Incorrect boot loader search path, no java runtime image or " JAVA_BASE_NAME " exploded build");
 658       struct stat st;
 659       if (os::stat(path, &st) == 0) {
 660         // Directory found
 661         if (jimage_exists()) {
 662           assert(Arguments::has_jimage(), "sanity check");
 663           const char* canonical_path = get_canonical_path(path, current);
 664           assert(canonical_path != nullptr, "canonical_path issue");
 665 
 666           // Hand over lifecycle control of the JImage file to the _jrt_entry singleton
 667           // (see ClassPathImageEntry::close_jimage). The image must be initialized by now.
 668           _jrt_entry = new ClassPathImageEntry(canonical_path);
 669           assert(_jrt_entry != nullptr && _jrt_entry->is_modules_image(), "No java runtime image present");

 670         } // else it's an exploded build.
 671       } else {
 672         // If path does not exist, exit
 673         vm_exit_during_initialization("Unable to establish the boot loader search path", path);
 674       }
 675       set_base_piece = false;
 676     } else {
 677       // Every entry on the boot class path after the initial base piece,
 678       // which is set by os::set_boot_path(), is considered an appended entry.
 679       update_class_path_entry_list(current, path);
 680     }
 681   }
 682 }
 683 
 684 // Gets the exploded path for the named module. The memory for the path
 685 // is allocated on the C heap if `c_heap` is true otherwise in the resource area.
 686 static const char* get_exploded_module_path(const char* module_name, bool c_heap) {
 687   const char *home = Arguments::get_java_home();
 688   const char file_sep = os::file_separator()[0];
 689   // 10 represents the length of "modules" (7) + 2 file separators + \0
 690   size_t len = strlen(home) + strlen(module_name) + 10;
 691   char *path = c_heap ? NEW_C_HEAP_ARRAY(char, len, mtModule) : NEW_RESOURCE_ARRAY(char, len);
 692   jio_snprintf(path, len, "%s%cmodules%c%s", home, file_sep, file_sep, module_name);
 693   return path;
 694 }
 695 
 696 // Gets a preview path for a given class path as a resource.
 697 static const char* get_preview_path(const char* path) {
 698   const char file_sep = os::file_separator()[0];
 699   // 18 represents the length of "META-INF" (8) + "preview" (7) + 2 file separators + \0
 700   size_t len = strlen(path) + 18;
 701   char *preview_path = NEW_RESOURCE_ARRAY(char, len);
 702   jio_snprintf(preview_path, len, "%s%cMETA-INF%cpreview", path, file_sep, file_sep);
 703   return preview_path;
 704 }
 705 
 706 // During an exploded modules build, each module defined to the boot loader
 707 // will be added to the ClassLoader::_exploded_entries array.
 708 void ClassLoader::add_to_exploded_build_list(JavaThread* current, Symbol* module_sym) {
 709   assert(!ClassLoader::has_jrt_entry(), "Exploded build not applicable");
 710   assert(_exploded_entries != nullptr, "_exploded_entries was not initialized");
 711 
 712   // Find the module's symbol
 713   ResourceMark rm(current);
 714   const char *module_name = module_sym->as_C_string();
 715   const char *path = get_exploded_module_path(module_name, false);
 716 
 717   struct stat st;
 718   if (os::stat(path, &st) == 0) {
 719     // Directory found
 720     ClassPathEntry* new_entry = create_class_path_entry(current, path, &st);

 721     // If the path specification is valid, enter it into this module's list.
 722     // There is no need to check for duplicate modules in the exploded entry list,
 723     // since no two modules with the same name can be defined to the boot loader.
 724     // This is checked at module definition time in Modules::define_module.
 725     if (new_entry != nullptr) {
 726       ModuleClassPathList* module_cpl = new ModuleClassPathList(module_sym);
 727       log_info(class, load)("path: %s", path);
 728 
 729       // If we are in preview mode, attempt to add a preview entry *before* the
 730       // new class path entry if a preview path exists.
 731       if (is_preview_enabled()) {
 732         const char* preview_path = get_preview_path(path);
 733         if (os::stat(preview_path, &st) == 0) {
 734           ClassPathEntry* preview_entry = create_class_path_entry(current, preview_path, &st);
 735           if (preview_entry != nullptr) {
 736             module_cpl->add_to_list(preview_entry);
 737             log_info(class, load)("preview path: %s", preview_path);
 738           }
 739         }
 740       }
 741 
 742       module_cpl->add_to_list(new_entry);
 743       {
 744         MutexLocker ml(current, Module_lock);
 745         _exploded_entries->push(module_cpl);
 746       }

 747     }
 748   }
 749 }
 750 
 751 jzfile* ClassLoader::open_zip_file(const char* canonical_path, char** error_msg, JavaThread* thread) {
 752   // enable call to C land
 753   ThreadToNativeFromVM ttn(thread);
 754   HandleMark hm(thread);
 755   return ZipLibrary::open(canonical_path, error_msg);
 756 }
 757 
 758 ClassPathEntry* ClassLoader::create_class_path_entry(JavaThread* current,
 759                                                      const char *path, const struct stat* st) {
 760   ClassPathEntry* new_entry = nullptr;
 761   if ((st->st_mode & S_IFMT) == S_IFREG) {
 762     ResourceMark rm(current);
 763     // Regular file, should be a zip file
 764     // Canonicalized filename
 765     const char* canonical_path = get_canonical_path(path, current);
 766     if (canonical_path == nullptr) {
 767       return nullptr;
 768     }
 769     char* error_msg = nullptr;
 770     jzfile* zip = open_zip_file(canonical_path, &error_msg, current);
 771     if (zip != nullptr && error_msg == nullptr) {
 772       new_entry = new ClassPathZipEntry(zip, path);
 773     } else {
 774       return nullptr;
 775     }
 776     log_info(class, path)("opened: %s", path);
 777     log_info(class, load)("opened: %s", path);
 778   } else {
 779     // Directory
 780     new_entry = new ClassPathDirEntry(path);
 781     log_info(class, load)("path: %s", path);
 782   }
 783   return new_entry;
 784 }
 785 
 786 
 787 // Create a class path zip entry for a given path (return null if not found
 788 // or zip/JAR file cannot be opened)
 789 ClassPathZipEntry* ClassLoader::create_class_path_zip_entry(const char *path) {
 790   // check for a regular file
 791   struct stat st;
 792   if (os::stat(path, &st) == 0) {
 793     if ((st.st_mode & S_IFMT) == S_IFREG) {
 794       JavaThread* thread = JavaThread::current();
 795       ResourceMark rm(thread);
 796       const char* canonical_path = get_canonical_path(path, thread);
 797       if (canonical_path != nullptr) {
 798         char* error_msg = nullptr;
 799         jzfile* zip = open_zip_file(canonical_path, &error_msg, thread);
 800         if (zip != nullptr && error_msg == nullptr) {
 801           // create using canonical path
 802           return new ClassPathZipEntry(zip, canonical_path);
 803         }
 804       }
 805     }
 806   }
 807   return nullptr;
 808 }
 809 
 810 // The boot append entries are added with a lock, and read lock free.
 811 void ClassLoader::add_to_boot_append_entries(ClassPathEntry *new_entry) {
 812   if (new_entry != nullptr) {
 813     MutexLocker ml(Bootclasspath_lock, Mutex::_no_safepoint_check_flag);
 814     if (_last_append_entry == nullptr) {
 815       _last_append_entry = new_entry;
 816       assert(first_append_entry() == nullptr, "boot loader's append class path entry list not empty");
 817       AtomicAccess::release_store(&_first_append_entry_list, new_entry);
 818     } else {
 819       _last_append_entry->set_next(new_entry);
 820       _last_append_entry = new_entry;
 821     }
 822   }
 823 }
 824 
 825 // Returns true IFF the file/dir exists and the entry was successfully created.
 826 bool ClassLoader::update_class_path_entry_list(JavaThread* current, const char *path) {
 827   struct stat st;
 828   if (os::stat(path, &st) == 0) {
 829     // File or directory found
 830     ClassPathEntry* new_entry = nullptr;
 831     new_entry = create_class_path_entry(current, path, &st);
 832     if (new_entry == nullptr) {
 833       return false;
 834     }
 835 
 836     // Do not reorder the bootclasspath which would break get_system_package().
 837     // Add new entry to linked list
 838     add_to_boot_append_entries(new_entry);
 839     return true;
 840   } else {
 841     return false;
 842   }
 843 }
 844 
 845 static void print_module_entry_table(const GrowableArray<ModuleClassPathList*>* const module_list) {
 846   ResourceMark rm;
 847   int num_of_entries = module_list->length();
 848   for (int i = 0; i < num_of_entries; i++) {
 849     ClassPathEntry* e;
 850     ModuleClassPathList* mpl = module_list->at(i);
 851     tty->print("%s=", mpl->module_name()->as_C_string());
 852     e = mpl->module_first_entry();
 853     while (e != nullptr) {
 854       tty->print("%s", e->name());
 855       e = e->next();
 856       if (e != nullptr) {
 857         tty->print("%s", os::path_separator());
 858       }
 859     }
 860     tty->print(" ;");
 861   }
 862 }
 863 
 864 void ClassLoader::print_bootclasspath() {
 865   ClassPathEntry* e;
 866   tty->print("[bootclasspath= ");
 867 
 868   // Print --patch-module module/path specifications first
 869   if (_patch_mod_entries != nullptr) {
 870     print_module_entry_table(_patch_mod_entries);
 871   }
 872 
 873   // [jimage | exploded modules build]
 874   if (has_jrt_entry()) {
 875     // Print the location of the java runtime image
 876     tty->print("%s ;", _jrt_entry->name());
 877   } else {
 878     // Print exploded module build path specifications
 879     if (_exploded_entries != nullptr) {
 880       print_module_entry_table(_exploded_entries);
 881     }
 882   }
 883 
 884   // appended entries
 885   e = first_append_entry();
 886   while (e != nullptr) {
 887     tty->print("%s ;", e->name());
 888     e = e->next();
 889   }
 890   tty->print_cr("]");
 891 }
 892 
 893 void* ClassLoader::dll_lookup(void* lib, const char* name, const char* path) {
 894   void* func = os::dll_lookup(lib, name);
 895   if (func == nullptr) {
 896     char msg[256] = "";
 897     jio_snprintf(msg, sizeof(msg), "Could not resolve \"%s\"", name);
 898     vm_exit_during_initialization(msg, path);
 899   }
 900   return func;
 901 }
 902 
 903 void ClassLoader::load_java_library() {
 904   assert(CanonicalizeEntry == nullptr, "should not load java library twice");
 905   if (is_vm_statically_linked()) {
 906     CanonicalizeEntry = CAST_TO_FN_PTR(canonicalize_fn_t, os::lookup_function("JDK_Canonicalize"));
 907     assert(CanonicalizeEntry != nullptr, "could not lookup JDK_Canonicalize");
 908     return;
 909   }
 910 
 911   void *javalib_handle = os::native_java_library();
 912   if (javalib_handle == nullptr) {
 913     vm_exit_during_initialization("Unable to load java library", nullptr);
 914   }
 915 
 916   CanonicalizeEntry = CAST_TO_FN_PTR(canonicalize_fn_t, dll_lookup(javalib_handle, "JDK_Canonicalize", nullptr));
 917   assert(CanonicalizeEntry != nullptr, "could not lookup JDK_Canonicalize in java library");
 918 }
 919 
 920 void ClassLoader::load_jimage_library() {
 921   assert(JImageOpen == nullptr, "should not load jimage library twice");
 922 
 923   if (is_vm_statically_linked()) {
 924       JImageOpen = CAST_TO_FN_PTR(JImageOpen_t, os::lookup_function("JIMAGE_Open"));
 925       JImageClose = CAST_TO_FN_PTR(JImageClose_t, os::lookup_function("JIMAGE_Close"));
 926       JImageFindResource = CAST_TO_FN_PTR(JImageFindResource_t, os::lookup_function("JIMAGE_FindResource"));
 927       JImageGetResource = CAST_TO_FN_PTR(JImageGetResource_t, os::lookup_function("JIMAGE_GetResource"));
 928       assert(JImageOpen != nullptr && JImageClose != nullptr &&
 929             JImageFindResource != nullptr && JImageGetResource != nullptr,
 930             "could not lookup all jimage library functions");
 931       return;
 932     }
 933 
 934   char path[JVM_MAXPATHLEN];
 935   char ebuf[1024];
 936   void* handle = nullptr;
 937   if (os::dll_locate_lib(path, sizeof(path), Arguments::get_dll_dir(), "jimage")) {
 938     handle = os::dll_load(path, ebuf, sizeof ebuf);
 939   }
 940   if (handle == nullptr) {
 941     vm_exit_during_initialization("Unable to load jimage library", path);
 942   }
 943 
 944   JImageOpen = CAST_TO_FN_PTR(JImageOpen_t, dll_lookup(handle, "JIMAGE_Open", path));
 945   JImageClose = CAST_TO_FN_PTR(JImageClose_t, dll_lookup(handle, "JIMAGE_Close", path));
 946   JImageFindResource = CAST_TO_FN_PTR(JImageFindResource_t, dll_lookup(handle, "JIMAGE_FindResource", path));
 947   JImageGetResource = CAST_TO_FN_PTR(JImageGetResource_t, dll_lookup(handle, "JIMAGE_GetResource", path));
 948   assert(JImageOpen != nullptr && JImageClose != nullptr &&
 949         JImageFindResource != nullptr && JImageGetResource != nullptr,
 950         "could not lookup all jimage library functions in jimage library");
 951 }
 952 
 953 int ClassLoader::crc32(int crc, const char* buf, int len) {
 954   return ZipLibrary::crc32(crc, (const jbyte*)buf, len);
 955 }
 956 
 957 oop ClassLoader::get_system_package(const char* name, TRAPS) {
 958   // Look up the name in the boot loader's package entry table.
 959   if (name != nullptr) {
 960     TempNewSymbol package_sym = SymbolTable::new_symbol(name);
 961     // Look for the package entry in the boot loader's package entry table.
 962     PackageEntry* package =
 963       ClassLoaderData::the_null_class_loader_data()->packages()->lookup_only(package_sym);
 964 
 965     // Return null if package does not exist or if no classes in that package
 966     // have been loaded.
 967     if (package != nullptr && package->has_loaded_class()) {
 968       ModuleEntry* module = package->module();
 969       if (module->location() != nullptr) {
 970         ResourceMark rm(THREAD);
 971         Handle ml = java_lang_String::create_from_str(
 972           module->location()->as_C_string(), THREAD);
 973         return ml();
 974       }
 975       // Return entry on boot loader class path.
 976       Handle cph = java_lang_String::create_from_str(
 977         ClassLoader::classpath_entry(package->classpath_index())->name(), THREAD);
 978       return cph();
 979     }
 980   }
 981   return nullptr;
 982 }
 983 
 984 objArrayOop ClassLoader::get_system_packages(TRAPS) {
 985   ResourceMark rm(THREAD);
 986   // List of pointers to PackageEntrys that have loaded classes.
 987   PackageEntryTable* pe_table =
 988       ClassLoaderData::the_null_class_loader_data()->packages();
 989   GrowableArray<PackageEntry*>* loaded_class_pkgs = pe_table->get_system_packages();
 990 
 991   // Allocate objArray and fill with java.lang.String
 992   objArrayOop r = oopFactory::new_objArray(vmClasses::String_klass(),
 993                                            loaded_class_pkgs->length(), CHECK_NULL);
 994   objArrayHandle result(THREAD, r);
 995   for (int x = 0; x < loaded_class_pkgs->length(); x++) {
 996     PackageEntry* package_entry = loaded_class_pkgs->at(x);
 997     Handle str = java_lang_String::create_from_symbol(package_entry->name(), CHECK_NULL);
 998     result->obj_at_put(x, str());
 999   }
1000   return result();
1001 }
1002 
1003 // caller needs ResourceMark
1004 const char* ClassLoader::file_name_for_class_name(const char* class_name,
1005                                                   int class_name_len) {
1006   assert(class_name != nullptr, "invariant");
1007   assert((int)strlen(class_name) == class_name_len, "invariant");
1008 
1009   static const char class_suffix[] = ".class";
1010   size_t class_suffix_len = sizeof(class_suffix);
1011 
1012   char* const file_name = NEW_RESOURCE_ARRAY(char,
1013                                              class_name_len +
1014                                              class_suffix_len); // includes term null
1015 
1016   strncpy(file_name, class_name, class_name_len);
1017   strncpy(&file_name[class_name_len], class_suffix, class_suffix_len);
1018 
1019   return file_name;
1020 }
1021 
1022 static ClassPathEntry* find_first_module_cpe(ModuleEntry* mod_entry,
1023                                              const GrowableArray<ModuleClassPathList*>* const module_list) {
1024   int num_of_entries = module_list->length();
1025   const Symbol* class_module_name = mod_entry->name();
1026 
1027   // Loop through all the modules in either the patch-module or exploded entries looking for module
1028   for (int i = 0; i < num_of_entries; i++) {
1029     ModuleClassPathList* module_cpl = module_list->at(i);
1030     Symbol* module_cpl_name = module_cpl->module_name();
1031 
1032     if (module_cpl_name->fast_compare(class_module_name) == 0) {
1033       // Class' module has been located.
1034       return module_cpl->module_first_entry();
1035     }
1036   }
1037   return nullptr;
1038 }
1039 
1040 
1041 // Search the module list for the class file stream based on the file name and java package
1042 ClassFileStream* ClassLoader::search_module_entries(JavaThread* current,
1043                                                     const GrowableArray<ModuleClassPathList*>* const module_list,
1044                                                     PackageEntry* pkg_entry, // Java package entry derived from the class name
1045                                                     const char* const file_name) {
1046   ClassFileStream* stream = nullptr;
1047 
1048   // Find the defining module in the boot loader's module entry table
1049   ModuleEntry* mod_entry = (pkg_entry != nullptr) ? pkg_entry->module() : nullptr;
1050 
1051   // If the module system has not defined java.base yet, then
1052   // classes loaded are assumed to be defined to java.base.
1053   // When java.base is eventually defined by the module system,
1054   // all packages of classes that have been previously loaded
1055   // are verified in ModuleEntryTable::verify_javabase_packages().
1056   if (!Universe::is_module_initialized() &&
1057       !ModuleEntryTable::javabase_defined() &&
1058       mod_entry == nullptr) {
1059     mod_entry = ModuleEntryTable::javabase_moduleEntry();
1060   }
1061 
1062   // The module must be a named module
1063   ClassPathEntry* e = nullptr;
1064   if (mod_entry != nullptr && mod_entry->is_named()) {
1065     if (module_list == _exploded_entries) {
1066       // The exploded build entries can be added to at any time so a lock is
1067       // needed when searching them.
1068       assert(!ClassLoader::has_jrt_entry(), "Must be exploded build");
1069       MutexLocker ml(current, Module_lock);
1070       e = find_first_module_cpe(mod_entry, module_list);
1071     } else {
1072       e = find_first_module_cpe(mod_entry, module_list);
1073     }
1074   }
1075 
1076   // Try to load the class from the module's ClassPathEntry list.
1077   while (e != nullptr) {
1078     stream = e->open_stream(current, file_name);
1079     // No context.check is required since CDS is not supported
1080     // for an exploded modules build or if --patch-module is specified.
1081     if (nullptr != stream) {
1082       return stream;
1083     }
1084     e = e->next();
1085   }
1086   // If the module was located, break out even if the class was not
1087   // located successfully from that module's ClassPathEntry list.
1088   // There will not be another valid entry for that module.
1089   return nullptr;
1090 }
1091 
1092 // Called by the boot classloader to load classes
1093 InstanceKlass* ClassLoader::load_class(Symbol* name, PackageEntry* pkg_entry, bool search_append_only, TRAPS) {
1094   assert(name != nullptr, "invariant");
1095 
1096   ResourceMark rm(THREAD);
1097   HandleMark hm(THREAD);
1098 
1099   const char* const class_name = name->as_C_string();
1100 
1101   EventMarkClassLoading m("Loading class %s", class_name);
1102 
1103   const char* const file_name = file_name_for_class_name(class_name,
1104                                                          name->utf8_length());
1105   assert(file_name != nullptr, "invariant");
1106 
1107   // Lookup stream for parsing .class file
1108   ClassFileStream* stream = nullptr;
1109   s2 classpath_index = 0;
1110   ClassPathEntry* e = nullptr;
1111   bool is_patched = false;
1112 
1113   // If search_append_only is true, boot loader visibility boundaries are
1114   // set to be _first_append_entry to the end. This includes:
1115   //   [-Xbootclasspath/a]; [jvmti appended entries]
1116   //
1117   // If search_append_only is false, boot loader visibility boundaries are
1118   // set to be the --patch-module entries plus the base piece. This includes:
1119   //   [--patch-module=<module>=<file>(<pathsep><file>)*]; [jimage | exploded module build]
1120   //
1121 
1122   // Load Attempt #1: --patch-module
1123   // Determine the class' defining module.  If it appears in the _patch_mod_entries,
1124   // attempt to load the class from those locations specific to the module.
1125   // Specifications to --patch-module can contain a partial number of classes
1126   // that are part of the overall module definition.  So if a particular class is not
1127   // found within its module specification, the search should continue to Load Attempt #2.
1128   // Note: The --patch-module entries are never searched if the boot loader's
1129   //       visibility boundary is limited to only searching the append entries.
1130   if (_patch_mod_entries != nullptr && !search_append_only) {
1131     // At CDS dump time, the --patch-module entries are ignored. That means a
1132     // class is still loaded from the runtime image even if it might
1133     // appear in the _patch_mod_entries. The runtime shared class visibility
1134     // check will determine if a shared class is visible based on the runtime
1135     // environment, including the runtime --patch-module setting.
1136     if (!Arguments::is_valhalla_enabled()) {
1137       // Dynamic dumping requires UseSharedSpaces to be enabled. Since --patch-module
1138       // is not supported with UseSharedSpaces, we can never come here during dynamic dumping.
1139       assert(!CDSConfig::is_dumping_archive(), "CDS doesn't support --patch-module during dumping");
1140     }
1141     if (Arguments::is_valhalla_enabled() || !CDSConfig::is_dumping_static_archive()) {
1142       stream = search_module_entries(THREAD, _patch_mod_entries, pkg_entry, file_name);
1143       if (stream != nullptr) {
1144         is_patched = true;
1145       }
1146     }
1147   }
1148 
1149   // Load Attempt #2: [jimage | exploded build]
1150   if (!search_append_only && (nullptr == stream)) {
1151     if (has_jrt_entry()) {
1152       e = _jrt_entry;
1153       stream = _jrt_entry->open_stream(THREAD, file_name);
1154     } else {
1155       // Exploded build - attempt to locate class in its defining module's location.
1156       assert(_exploded_entries != nullptr, "No exploded build entries present");
1157       assert(!CDSConfig::is_dumping_archive(), "CDS dumping doesn't support exploded build");
1158       stream = search_module_entries(THREAD, _exploded_entries, pkg_entry, file_name);
1159     }
1160   }
1161 
1162   // Load Attempt #3: [-Xbootclasspath/a]; [jvmti appended entries]
1163   if (search_append_only && (nullptr == stream)) {
1164     // For the boot loader append path search, the starting classpath_index
1165     // for the appended piece is always 1 to account for either the
1166     // _jrt_entry or the _exploded_entries.
1167     assert(classpath_index == 0, "The classpath_index has been incremented incorrectly");
1168     classpath_index = 1;
1169 
1170     e = first_append_entry();
1171     while (e != nullptr) {
1172       stream = e->open_stream(THREAD, file_name);
1173       if (nullptr != stream) {
1174         break;
1175       }
1176       e = e->next();
1177       ++classpath_index;
1178     }
1179   }
1180 
1181   if (nullptr == stream) {
1182     return nullptr;
1183   }
1184 
1185   ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
1186   Handle protection_domain;
1187   ClassLoadInfo cl_info(protection_domain);
1188 
1189   InstanceKlass* result = KlassFactory::create_from_stream(stream,
1190                                                            name,
1191                                                            loader_data,
1192                                                            cl_info,
1193                                                            CHECK_NULL);
1194   result->set_classpath_index(classpath_index);
1195   if (is_patched) {
1196     result->set_shared_classpath_index(0);
1197   }
1198   return result;
1199 }
1200 
1201 #if INCLUDE_CDS
1202 static const char* skip_uri_protocol(const char* source) {
1203   if (strncmp(source, "file:", 5) == 0) {
1204     // file: protocol path could start with file:/ or file:///
1205     // locate the char after all the forward slashes
1206     int offset = 5;
1207     while (*(source + offset) == '/') {
1208         offset++;
1209     }
1210     source += offset;
1211   // for non-windows platforms, move back one char as the path begins with a '/'
1212 #ifndef _WINDOWS
1213     source -= 1;
1214 #endif
1215   } else if (strncmp(source, "jrt:/", 5) == 0) {
1216     source += 5;
1217   }
1218   return source;
1219 }
1220 
1221 static char decode_percent_encoded(const char *str, size_t& index) {
1222   if (str[index] == '%'
1223       && isxdigit(str[index + 1])
1224       && isxdigit(str[index + 2])) {
1225     char hex[3];
1226     hex[0] = str[index + 1];
1227     hex[1] = str[index + 2];
1228     hex[2] = '\0';
1229     index += 2;
1230     return (char) strtol(hex, nullptr, 16);
1231   }
1232   return str[index];
1233 }
1234 
1235 char* ClassLoader::uri_to_path(const char* uri) {
1236   const size_t len = strlen(uri) + 1;
1237   char* path = NEW_RESOURCE_ARRAY(char, len);
1238 
1239   uri = skip_uri_protocol(uri);
1240 
1241   if (strncmp(uri, "//", 2) == 0) {
1242     // Skip the empty "authority" part
1243     uri += 2;
1244   }
1245 
1246 #ifdef _WINDOWS
1247   if (uri[0] == '/') {
1248     // Absolute path name on Windows does not begin with a slash
1249     uri += 1;
1250   }
1251 #endif
1252 
1253   size_t path_index = 0;
1254   for (size_t i = 0; i < strlen(uri); ++i) {
1255     char decoded = decode_percent_encoded(uri, i);
1256     path[path_index++] = decoded;
1257   }
1258   path[path_index] = '\0';
1259   return path;
1260 }
1261 
1262 // Record the shared classpath index and loader type for classes loaded
1263 // by the builtin loaders at dump time.
1264 void ClassLoader::record_result(JavaThread* current, InstanceKlass* ik,
1265                                 const ClassFileStream* stream, bool redefined) {
1266   assert(CDSConfig::is_dumping_archive(), "sanity");
1267   assert(stream != nullptr, "sanity");
1268 
1269   if (ik->is_hidden()) {
1270     record_hidden_class(ik);
1271     return;
1272   }
1273 
1274   if (ik->shared_classpath_index() == 0 && ik->defined_by_boot_loader()) {
1275     return;
1276   }
1277 
1278   oop loader = ik->class_loader();
1279   char* src = (char*)stream->source();
1280   if (src == nullptr) {
1281     ik->set_shared_classpath_index(-1); // unsupported location
1282     return;
1283   }
1284 
1285   if (!SystemDictionaryShared::is_builtin_loader(ik->class_loader_data())) {
1286     // A class loaded by a user-defined classloader.
1287     assert(ik->shared_classpath_index() < 0, "not assigned yet");
1288     ik->set_shared_classpath_index(UNREGISTERED_INDEX);
1289     SystemDictionaryShared::set_shared_class_misc_info(ik, (ClassFileStream*)stream);
1290     return;
1291   }
1292 
1293   assert(has_jrt_entry(), "CDS dumping does not support exploded JDK build");
1294 
1295   ResourceMark rm(current);
1296   int classpath_index = -1;
1297   bool found_invalid = false;
1298 
1299   PackageEntry* pkg_entry = ik->package();
1300 
1301   if (!AOTClassLocationConfig::dumptime_is_ready()) {
1302     // The shared path table is set up after module system initialization.
1303     // The path table contains no entry before that. Any classes loaded prior
1304     // to the setup of the shared path table must be from the modules image.
1305     assert(stream->from_boot_loader_modules_image(), "stream must be loaded by boot loader from modules image");
1306     classpath_index = 0;
1307   } else {
1308     // Save the path from the file: protocol or the module name from the jrt: protocol
1309     // if no protocol prefix is found, path is the same as stream->source(). This path
1310     // must be valid since the class has been successfully parsed.
1311     const char* path = ClassLoader::uri_to_path(src);
1312     assert(path != nullptr, "sanity");
1313     AOTClassLocationConfig::dumptime_iterate([&] (AOTClassLocation* cl) {
1314       int i = cl->index();
1315       // for index 0 and the stream->source() is the modules image or has the jrt: protocol.
1316       // The class must be from the runtime modules image.
1317       if (cl->is_modules_image() && (stream->from_boot_loader_modules_image() || string_starts_with(src, "jrt:"))) {
1318         classpath_index = i;
1319       } else if (os::same_files(cl->path(), path)) {
1320         // If the path (from the class stream source) is the same as the shared
1321         // class or module path, then we have a match.
1322         // src may come from the App/Platform class loaders, which would canonicalize
1323         // the file name. We cannot use strcmp to check for equality against cs->path().
1324         // We must use os::same_files (which is faster than canonicalizing cs->path()).
1325 
1326         // null pkg_entry and pkg_entry in an unnamed module implies the class
1327         // is from the -cp or boot loader append path which consists of -Xbootclasspath/a
1328         // and jvmti appended entries.
1329         if ((pkg_entry == nullptr) || (pkg_entry->in_unnamed_module())) {
1330           // Ensure the index is within the -cp range before assigning
1331           // to the classpath_index.
1332           if (SystemDictionary::is_system_class_loader(loader) && cl->from_app_classpath()) {
1333             classpath_index = i;
1334           } else {
1335             if (cl->from_boot_classpath()) {
1336               if (loader != nullptr) {
1337                 // Probably loaded by jdk/internal/loader/ClassLoaders$BootClassLoader. Don't archive
1338                 // such classes.
1339                 found_invalid = true;
1340               } else {
1341                 classpath_index = i;
1342               }
1343             }
1344           }
1345         } else {
1346           // A class from a named module from the --module-path. Ensure the index is
1347           // within the --module-path range before assigning to the classpath_index.
1348           if ((pkg_entry != nullptr) && !(pkg_entry->in_unnamed_module()) && cl->from_module_path()) {
1349             classpath_index = i;
1350           }
1351         }
1352       }
1353       if (classpath_index >= 0 || found_invalid) {
1354         return false; // Break the AOTClassLocationConfig::dumptime_iterate() loop.
1355       } else {
1356         return true; // Keep iterating
1357       }
1358     });
1359   }
1360 
1361   if (found_invalid) {
1362     assert(classpath_index == -1, "sanity");
1363   }
1364 
1365   const char* const class_name = ik->name()->as_C_string();
1366   const char* const file_name = file_name_for_class_name(class_name,
1367                                                          ik->name()->utf8_length());
1368   assert(file_name != nullptr, "invariant");
1369   record_result_for_builtin_loader(checked_cast<s2>(classpath_index), ik, redefined);
1370 }
1371 
1372 void ClassLoader::record_result_for_builtin_loader(s2 classpath_index, InstanceKlass* result, bool redefined) {
1373   assert(CDSConfig::is_dumping_archive(), "sanity");
1374 
1375   oop loader = result->class_loader();
1376   if (SystemDictionary::is_system_class_loader(loader)) {
1377     AOTClassLocationConfig::dumptime_set_has_app_classes();
1378   } else if (SystemDictionary::is_platform_class_loader(loader)) {
1379     AOTClassLocationConfig::dumptime_set_has_platform_classes();
1380   } else {
1381     precond(loader == nullptr);
1382   }
1383 
1384   if (CDSConfig::is_dumping_preimage_static_archive() || CDSConfig::is_dumping_dynamic_archive()) {
1385     if (!AOTClassLocationConfig::dumptime()->is_valid_classpath_index(classpath_index, result)) {
1386       classpath_index = -1;
1387     }
1388   }
1389 
1390   AOTClassLocationConfig::dumptime_update_max_used_index(classpath_index);
1391   result->set_shared_classpath_index(classpath_index);
1392 }
1393 
1394 void ClassLoader::record_hidden_class(InstanceKlass* ik) {
1395   assert(ik->is_hidden(), "must be");
1396 
1397   if (ik->defined_by_other_loaders()) {
1398     // We don't archive hidden classes for non-builtin loaders.
1399     return;
1400   }
1401 
1402   if (HeapShared::is_lambda_proxy_klass(ik)) {
1403     InstanceKlass* nest_host = ik->nest_host_not_null();
1404     ik->set_shared_classpath_index(nest_host->shared_classpath_index());
1405   } else if (HeapShared::is_lambda_form_klass(ik)) {
1406     ik->set_shared_classpath_index(0);
1407   } else {
1408     // Generated invoker classes.
1409     if (ik->defined_by_app_loader()) {
1410       ik->set_shared_classpath_index(AOTClassLocationConfig::dumptime()->app_cp_start_index());
1411     } else {
1412       ik->set_shared_classpath_index(0);
1413     }
1414   }
1415 }
1416 
1417 void ClassLoader::append_boot_classpath(ClassPathEntry* new_entry) {
1418   if (CDSConfig::is_using_archive()) {
1419     warning("Sharing is only supported for boot loader classes because bootstrap classpath has been appended");
1420     FileMapInfo::current_info()->set_has_platform_or_app_classes(false);
1421     if (DynamicArchive::is_mapped()) {
1422       FileMapInfo::dynamic_info()->set_has_platform_or_app_classes(false);
1423     }
1424   }
1425   add_to_boot_append_entries(new_entry);
1426 }
1427 #endif // INCLUDE_CDS
1428 
1429 // Initialize the class loader's access to methods in libzip.  Parse and
1430 // process the boot classpath into a list ClassPathEntry objects.  Once
1431 // this list has been created, it must not change order (see class PackageInfo)
1432 // it can be appended to and is by jvmti.
1433 
1434 void ClassLoader::initialize(TRAPS) {
1435   if (UsePerfData) {
1436     // jvmstat performance counters
1437     NEWPERFTICKCOUNTER(_perf_accumulated_time, SUN_CLS, "time");
1438     NEWPERFTICKCOUNTER(_perf_class_init_time, SUN_CLS, "classInitTime");
1439     NEWPERFTICKCOUNTER(_perf_class_init_selftime, SUN_CLS, "classInitTime.self");
1440     NEWPERFTICKCOUNTER(_perf_class_verify_time, SUN_CLS, "classVerifyTime");
1441     NEWPERFTICKCOUNTER(_perf_class_verify_selftime, SUN_CLS, "classVerifyTime.self");
1442     NEWPERFTICKCOUNTER(_perf_class_link_time, SUN_CLS, "classLinkedTime");
1443     NEWPERFTICKCOUNTER(_perf_class_link_selftime, SUN_CLS, "classLinkedTime.self");
1444     NEWPERFEVENTCOUNTER(_perf_classes_inited, SUN_CLS, "initializedClasses");
1445     NEWPERFEVENTCOUNTER(_perf_classes_linked, SUN_CLS, "linkedClasses");
1446     NEWPERFEVENTCOUNTER(_perf_classes_verified, SUN_CLS, "verifiedClasses");
1447 
1448     NEWPERFTICKCOUNTER(_perf_shared_classload_time, SUN_CLS, "sharedClassLoadTime");
1449     NEWPERFTICKCOUNTER(_perf_sys_classload_time, SUN_CLS, "sysClassLoadTime");
1450     NEWPERFTICKCOUNTER(_perf_app_classload_time, SUN_CLS, "appClassLoadTime");
1451     NEWPERFTICKCOUNTER(_perf_app_classload_selftime, SUN_CLS, "appClassLoadTime.self");
1452     NEWPERFEVENTCOUNTER(_perf_app_classload_count, SUN_CLS, "appClassLoadCount");
1453     NEWPERFTICKCOUNTER(_perf_define_appclasses, SUN_CLS, "defineAppClasses");
1454     NEWPERFTICKCOUNTER(_perf_define_appclass_time, SUN_CLS, "defineAppClassTime");
1455     NEWPERFTICKCOUNTER(_perf_define_appclass_selftime, SUN_CLS, "defineAppClassTime.self");
1456     NEWPERFBYTECOUNTER(_perf_app_classfile_bytes_read, SUN_CLS, "appClassBytes");
1457     NEWPERFBYTECOUNTER(_perf_sys_classfile_bytes_read, SUN_CLS, "sysClassBytes");
1458     NEWPERFEVENTCOUNTER(_unsafe_defineClassCallCounter, SUN_CLS, "unsafeDefineClassCalls");
1459     NEWPERFTICKCOUNTER(_perf_secondary_hash_time, SUN_CLS, "secondarySuperHashTime");
1460 
1461     if (log_is_enabled(Info, perf, class, link)) {
1462       NEWPERFTICKCOUNTER(_perf_ik_link_methods_time, SUN_CLS, "linkMethodsTime");
1463       NEWPERFTICKCOUNTER(_perf_method_adapters_time, SUN_CLS, "makeAdaptersTime");
1464       NEWPERFEVENTCOUNTER(_perf_ik_link_methods_count, SUN_CLS, "linkMethodsCount");
1465       NEWPERFEVENTCOUNTER(_perf_method_adapters_count, SUN_CLS, "makeAdaptersCount");
1466 
1467       NEWPERFTICKCOUNTER(_perf_resolve_indy_time, SUN_CLS, "resolve_invokedynamic_time");
1468       NEWPERFTICKCOUNTER(_perf_resolve_invokehandle_time, SUN_CLS, "resolve_invokehandle_time");
1469       NEWPERFTICKCOUNTER(_perf_resolve_mh_time, SUN_CLS, "resolve_MethodHandle_time");
1470       NEWPERFTICKCOUNTER(_perf_resolve_mt_time, SUN_CLS, "resolve_MethodType_time");
1471 
1472       NEWPERFEVENTCOUNTER(_perf_resolve_indy_count, SUN_CLS, "resolve_invokedynamic_count");
1473       NEWPERFEVENTCOUNTER(_perf_resolve_invokehandle_count, SUN_CLS, "resolve_invokehandle_count");
1474       NEWPERFEVENTCOUNTER(_perf_resolve_mh_count, SUN_CLS, "resolve_MethodHandle_count");
1475       NEWPERFEVENTCOUNTER(_perf_resolve_mt_count, SUN_CLS, "resolve_MethodType_count");
1476     }
1477   }
1478 
1479   // lookup java library entry points
1480   load_java_library();
1481   // jimage library entry points are loaded below, in lookup_vm_options
1482   setup_bootstrap_search_path(THREAD);
1483 }
1484 











1485 // Lookup VM options embedded in the modules jimage file
1486 char* ClassLoader::lookup_vm_options() {

1487   char modules_path[JVM_MAXPATHLEN];
1488   const char* fileSep = os::file_separator();
1489 
1490   // Initialize jimage library entry points
1491   load_jimage_library();
1492 
1493   jio_snprintf(modules_path, JVM_MAXPATHLEN, "%s%slib%smodules", Arguments::get_java_home(), fileSep, fileSep);
1494   if (jimage_open(modules_path)) {
1495     // Special case where we lookup the options string *before* set_preview_mode() is called.
1496     // Since VM arguments have not been parsed, and the ClassPathImageEntry singleton
1497     // has not been created yet, we access the JImage file directly in non-preview mode.
1498     jlong size;
1499     JImageLocationRef location =
1500             jimage_find_resource(JAVA_BASE_NAME, "jdk/internal/vm/options", /* is_preview */ false, &size);
1501     if (location != 0) {
1502       char *options = NEW_C_HEAP_ARRAY(char, size+1, mtClass);
1503       (*JImageGetResource)(jimage_non_null(), location, options, size);
1504       options[size] = '\0';
1505       return options;
1506     }
1507   }
1508   return nullptr;
1509 }
1510 
1511 // Finishes initializing the JImageFile (if present) by setting the access mode.
1512 void ClassLoader::set_preview_mode(bool enable_preview) {
1513   assert(Preview_mode == PREVIEW_MODE_UNINITIALIZED, "set_preview_mode must not be called twice");
1514   Preview_mode = enable_preview ? PREVIEW_MODE_ENABLE_PREVIEW : PREVIEW_MODE_DEFAULT;
1515 }
1516 
1517 bool ClassLoader::is_module_observable(const char* module_name) {
1518   assert(JImageOpen != nullptr, "jimage library should have been opened");
1519   if (!jimage_exists()) {
1520     struct stat st;
1521     const char *path = get_exploded_module_path(module_name, true);
1522     bool res = os::stat(path, &st) == 0;
1523     FREE_C_HEAP_ARRAY(char, path);
1524     return res;
1525   }
1526   // We don't expect preview mode (i.e. --enable-preview) to affect module visibility.
1527   jlong size;
1528   return jimage_find_resource(module_name, "module-info.class", /* is_preview */ false, &size) != 0;

1529 }
1530 
1531 jlong ClassLoader::classloader_time_ms() {
1532   return UsePerfData ?
1533     Management::ticks_to_ms(_perf_accumulated_time->get_value()) : -1;
1534 }
1535 
1536 jlong ClassLoader::class_init_count() {
1537   return UsePerfData ? _perf_classes_inited->get_value() : -1;
1538 }
1539 
1540 jlong ClassLoader::class_init_time_ms() {
1541   return UsePerfData ?
1542     Management::ticks_to_ms(_perf_class_init_time->get_value()) : -1;
1543 }
1544 
1545 jlong ClassLoader::class_verify_time_ms() {
1546   return UsePerfData ?
1547     Management::ticks_to_ms(_perf_class_verify_time->get_value()) : -1;
1548 }
1549 
1550 jlong ClassLoader::class_link_count() {
1551   return UsePerfData ? _perf_classes_linked->get_value() : -1;
1552 }
1553 
1554 jlong ClassLoader::class_link_time_ms() {
1555   return UsePerfData ?
1556     Management::ticks_to_ms(_perf_class_link_time->get_value()) : -1;
1557 }
1558 
1559 int ClassLoader::compute_Object_vtable() {
1560   // hardwired for JDK1.2 -- would need to duplicate class file parsing
1561   // code to determine actual value from file
1562   // Would be value '11' if finals were in vtable
1563   int JDK_1_2_Object_vtable_size = 5;
1564   return JDK_1_2_Object_vtable_size * vtableEntry::size();
1565 }
1566 
1567 
1568 void classLoader_init1() {
1569   EXCEPTION_MARK;
1570   ClassLoader::initialize(THREAD);
1571   if (HAS_PENDING_EXCEPTION) {
1572     vm_exit_during_initialization("ClassLoader::initialize() failed unexpectedly");
1573   }
1574 }
1575 
1576 // Complete the ClassPathEntry setup for the boot loader
1577 void ClassLoader::classLoader_init2(JavaThread* current) {
1578   // Setup the list of module/path pairs for --patch-module processing
1579   // This must be done after the SymbolTable is created in order
1580   // to use fast_compare on module names instead of a string compare.
1581   if (Arguments::get_patch_mod_prefix() != nullptr) {
1582     setup_patch_mod_entries();
1583   }
1584 
1585   // Create the ModuleEntry for java.base (must occur after setup_patch_mod_entries
1586   // to successfully determine if java.base has been patched)
1587   create_javabase();
1588 
1589   // Setup the initial java.base/path pair for the exploded build entries.
1590   // As more modules are defined during module system initialization, more
1591   // entries will be added to the exploded build array.
1592   if (!has_jrt_entry()) {
1593     assert(!CDSConfig::is_dumping_archive(), "not supported with exploded module builds");
1594     assert(!CDSConfig::is_using_archive(), "UsedSharedSpaces not supported with exploded module builds");
1595     // Set up the boot loader's _exploded_entries list.  Note that this gets
1596     // done before loading any classes, by the same thread that will
1597     // subsequently do the first class load. So, no lock is needed for this.
1598     assert(_exploded_entries == nullptr, "Should only get initialized once");
1599     _exploded_entries = new (mtModule)
1600       GrowableArray<ModuleClassPathList*>(EXPLODED_ENTRY_SIZE, mtModule);
1601     add_to_exploded_build_list(current, vmSymbols::java_base());
1602   }
1603 }
1604 
1605 char* ClassLoader::get_canonical_path(const char* orig, Thread* thread) {
1606   assert(orig != nullptr, "bad arguments");
1607   // caller needs to allocate ResourceMark for the following output buffer
1608   char* canonical_path = NEW_RESOURCE_ARRAY_IN_THREAD(thread, char, JVM_MAXPATHLEN);
1609   ResourceMark rm(thread);
1610   // os::native_path writes into orig_copy
1611   char* orig_copy = ResourceArea::strdup(thread, orig);
1612   if ((CanonicalizeEntry)(os::native_path(orig_copy), canonical_path, JVM_MAXPATHLEN) < 0) {
1613     return nullptr;
1614   }
1615   return canonical_path;
1616 }
1617 
1618 void ClassLoader::create_javabase() {
1619   JavaThread* current = JavaThread::current();
1620 
1621   // Create java.base's module entry for the boot
1622   // class loader prior to loading j.l.Object.
1623   ClassLoaderData* null_cld = ClassLoaderData::the_null_class_loader_data();
1624 
1625   // Get module entry table
1626   ModuleEntryTable* null_cld_modules = null_cld->modules();
1627   if (null_cld_modules == nullptr) {
1628     vm_exit_during_initialization("No ModuleEntryTable for the boot class loader");
1629   }
1630 
1631   {
1632     MutexLocker ml(current, Module_lock);
1633     if (ModuleEntryTable::javabase_moduleEntry() == nullptr) {  // may have been inited by CDS.
1634       ModuleEntry* jb_module = null_cld_modules->locked_create_entry(Handle(),
1635                                false, vmSymbols::java_base(), nullptr, nullptr, null_cld);
1636       if (jb_module == nullptr) {
1637         vm_exit_during_initialization("Unable to create ModuleEntry for " JAVA_BASE_NAME);
1638       }
1639       ModuleEntryTable::set_javabase_moduleEntry(jb_module);
1640     }
1641   }
1642 }
1643 
1644 // Please keep following two functions at end of this file. With them placed at top or in middle of the file,
1645 // they could get inlined by aggressive compiler, an unknown trick, see bug 6966589.
1646 void PerfClassTraceTime::initialize() {
1647   if (!UsePerfData) return;
1648 
1649   if (_eventp != nullptr) {
1650     // increment the event counter
1651     _eventp->inc();
1652   }
1653 
1654   // stop the current active thread-local timer to measure inclusive time
1655   _prev_active_event = -1;
1656   for (int i=0; i < EVENT_TYPE_COUNT; i++) {
1657      if (_timers[i].is_active()) {
1658        assert(_prev_active_event == -1, "should have only one active timer");
1659        _prev_active_event = i;
1660        _timers[i].stop();
1661      }
1662   }
1663 
1664   if (_recursion_counters == nullptr || (_recursion_counters[_event_type])++ == 0) {
1665     // start the inclusive timer if not recursively called
1666     _t.start();
1667   }
1668 
1669   // start thread-local timer of the given event type
1670    if (!_timers[_event_type].is_active()) {
1671     _timers[_event_type].start();
1672   }
1673 }
1674 
1675 PerfClassTraceTime::~PerfClassTraceTime() {
1676   if (!UsePerfData) return;
1677 
1678   // stop the thread-local timer as the event completes
1679   // and resume the thread-local timer of the event next on the stack
1680   _timers[_event_type].stop();
1681   jlong selftime = _timers[_event_type].ticks();
1682 
1683   if (_prev_active_event >= 0) {
1684     _timers[_prev_active_event].start();
1685   }
1686 
1687   if (_recursion_counters != nullptr && --(_recursion_counters[_event_type]) > 0) return;
1688 
1689   // increment the counters only on the leaf call
1690   _t.stop();
1691   _timep->inc(_t.ticks());
1692   if (_selftimep != nullptr) {
1693     _selftimep->inc(selftime);
1694   }
1695   // add all class loading related event selftime to the accumulated time counter
1696   ClassLoader::perf_accumulated_time()->inc(selftime);
1697 
1698   // reset the timer
1699   _timers[_event_type].reset();
1700 }
--- EOF ---