1 /* 2 * Copyright (c) 1997, 2023, 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 #ifndef SHARE_CLASSFILE_SYSTEMDICTIONARY_HPP 26 #define SHARE_CLASSFILE_SYSTEMDICTIONARY_HPP 27 28 #include "oops/oopHandle.hpp" 29 #include "runtime/handles.hpp" 30 #include "runtime/signature.hpp" 31 #include "utilities/vmEnums.hpp" 32 33 // The dictionary in each ClassLoaderData stores all loaded classes, either 34 // initiatied by its class loader or defined by its class loader: 35 // 36 // class loader -> ClassLoaderData -> [class, protection domain set] 37 // 38 // Classes are loaded lazily. The default VM class loader is 39 // represented as null. 40 41 // The underlying data structure is an open hash table (Dictionary) per 42 // ClassLoaderData with a fixed number of buckets. During loading the 43 // class loader object is locked, (for the VM loader a private lock object is used). 44 // The global SystemDictionary_lock is held for all additions into the ClassLoaderData 45 // dictionaries. TODO: fix lock granularity so that class loading can 46 // be done concurrently, but only by different loaders. 47 // 48 // During loading a placeholder (name, loader) is temporarily placed in 49 // a side data structure, and is used to detect ClassCircularityErrors. 50 // 51 // When class loading is finished, a new entry is added to the dictionary 52 // of the class loader and the placeholder is removed. Note that the protection 53 // domain field of the dictionary entry has not yet been filled in when 54 // the "real" dictionary entry is created. 55 // 56 // Clients of this class who are interested in finding if a class has 57 // been completely loaded -- not classes in the process of being loaded -- 58 // can read the dictionary unlocked. This is safe because 59 // - entries are only deleted when the class loader is not alive, when the 60 // entire dictionary is deleted. 61 // - entries must be fully formed before they are available to concurrent 62 // readers (we must ensure write ordering) 63 // 64 // Note that placeholders are deleted at any time, as they are removed 65 // when a class is completely loaded. Therefore, readers as well as writers 66 // of placeholders must hold the SystemDictionary_lock. 67 // 68 69 class BootstrapInfo; 70 class ClassFileStream; 71 class ClassLoadInfo; 72 class Dictionary; 73 class AllFieldStream; 74 class PackageEntry; 75 class GCTimer; 76 class EventClassLoad; 77 class Symbol; 78 79 class SystemDictionary : AllStatic { 80 friend class BootstrapInfo; 81 friend class vmClasses; 82 friend class VMStructs; 83 84 public: 85 86 // Returns a class with a given class name and class loader. Loads the 87 // class if needed. If not found a NoClassDefFoundError or a 88 // ClassNotFoundException is thrown, depending on the value on the 89 // throw_error flag. For most uses the throw_error argument should be set 90 // to true. 91 92 static Klass* resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS); 93 // Convenient call for null loader and protection domain. 94 static Klass* resolve_or_fail(Symbol* class_name, bool throw_error, TRAPS) { 95 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD); 96 } 97 98 // Returns a class with a given class name and class loader. 99 // Loads the class if needed. If not found null is returned. 100 static Klass* resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS); 101 // Version with null loader and protection domain 102 static Klass* resolve_or_null(Symbol* class_name, TRAPS) { 103 return resolve_or_null(class_name, Handle(), Handle(), THREAD); 104 } 105 106 // Resolve a superclass or superinterface. Called from ClassFileParser, 107 // parse_interfaces, resolve_instance_class_or_null, load_shared_class 108 // "class_name" is the class whose super class or interface is being resolved. 109 static InstanceKlass* resolve_with_circularity_detection_or_fail(Symbol* class_name, 110 Symbol* super_name, 111 Handle class_loader, 112 Handle protection_domain, 113 bool is_superclass, 114 TRAPS); 115 private: 116 // Parse the stream to create a hidden class. 117 // Used by jvm_lookup_define_class. 118 static InstanceKlass* resolve_hidden_class_from_stream(ClassFileStream* st, 119 Symbol* class_name, 120 Handle class_loader, 121 const ClassLoadInfo& cl_info, 122 TRAPS); 123 124 // Resolve a class from stream (called by jni_DefineClass and JVM_DefineClass) 125 // This class is added to the SystemDictionary. 126 static InstanceKlass* resolve_class_from_stream(ClassFileStream* st, 127 Symbol* class_name, 128 Handle class_loader, 129 const ClassLoadInfo& cl_info, 130 TRAPS); 131 132 static oop get_system_class_loader_impl(TRAPS); 133 static oop get_platform_class_loader_impl(TRAPS); 134 135 public: 136 137 // Resolve either a hidden or normal class from a stream of bytes, based on ClassLoadInfo 138 static InstanceKlass* resolve_from_stream(ClassFileStream* st, 139 Symbol* class_name, 140 Handle class_loader, 141 const ClassLoadInfo& cl_info, 142 TRAPS); 143 144 // Lookup an already loaded class. If not found null is returned. 145 static InstanceKlass* find_instance_klass(Thread* current, Symbol* class_name, 146 Handle class_loader, Handle protection_domain); 147 148 // Lookup an already loaded instance or array class. 149 // Do not make any queries to class loaders; consult only the cache. 150 // If not found null is returned. 151 static Klass* find_instance_or_array_klass(Thread* current, Symbol* class_name, 152 Handle class_loader, 153 Handle protection_domain); 154 155 // Lookup an instance or array class that has already been loaded 156 // either into the given class loader, or else into another class 157 // loader that is constrained (via loader constraints) to produce 158 // a consistent class. Do not take protection domains into account. 159 // Do not make any queries to class loaders; consult only the cache. 160 // Return null if the class is not found. 161 // 162 // This function is a strict superset of find_instance_or_array_klass. 163 // This function (the unchecked version) makes a conservative prediction 164 // of the result of the checked version, assuming successful lookup. 165 // If both functions return non-null, they must return the same value. 166 // Also, the unchecked version may sometimes be non-null where the 167 // checked version is null. This can occur in several ways: 168 // 1. No query has yet been made to the class loader. 169 // 2. The class loader was queried, but chose not to delegate. 170 // 3. ClassLoader.checkPackageAccess rejected a proposed protection domain. 171 // 4. Loading was attempted, but there was a linkage error of some sort. 172 // In all of these cases, the loader constraints on this type are 173 // satisfied, and it is safe for classes in the given class loader 174 // to manipulate strongly-typed values of the found class, subject 175 // to local linkage and access checks. 176 static Klass* find_constrained_instance_or_array_klass(Thread* current, 177 Symbol* class_name, 178 Handle class_loader); 179 180 static void classes_do(MetaspaceClosure* it); 181 // Iterate over all methods in all klasses 182 183 static void methods_do(void f(Method*)); 184 185 // Garbage collection support 186 187 // Unload (that is, break root links to) all unmarked classes and 188 // loaders. Returns "true" iff something was unloaded. 189 static bool do_unloading(GCTimer* gc_timer); 190 191 // Printing 192 static void print(); 193 static void print_on(outputStream* st); 194 static void dump(outputStream* st, bool verbose); 195 196 // Verification 197 static void verify(); 198 199 // Initialization 200 static void initialize(TRAPS); 201 202 public: 203 // Returns java system loader 204 static oop java_system_loader(); 205 206 // Returns java platform loader 207 static oop java_platform_loader(); 208 209 // Compute the java system and platform loaders 210 static void compute_java_loaders(TRAPS); 211 212 // Register a new class loader 213 static ClassLoaderData* register_loader(Handle class_loader, bool create_mirror_cld = false); 214 215 static void set_system_loader(ClassLoaderData *cld); 216 static void set_platform_loader(ClassLoaderData *cld); 217 218 static Symbol* check_signature_loaders(Symbol* signature, Klass* klass_being_linked, 219 Handle loader1, Handle loader2, bool is_method); 220 221 // JSR 292 222 // find a java.lang.invoke.MethodHandle.invoke* method for a given signature 223 // (asks Java to compute it if necessary, except in a compiler thread) 224 static Method* find_method_handle_invoker(Klass* klass, 225 Symbol* name, 226 Symbol* signature, 227 Klass* accessing_klass, 228 Handle *appendix_result, 229 TRAPS); 230 // for a given signature, find the internal MethodHandle method (linkTo* or invokeBasic) 231 // (does not ask Java, since this is a low-level intrinsic defined by the JVM) 232 static Method* find_method_handle_intrinsic(vmIntrinsicID iid, 233 Symbol* signature, 234 TRAPS); 235 236 // compute java_mirror (java.lang.Class instance) for a type ("I", "[[B", "LFoo;", etc.) 237 // Either the accessing_klass or the CL/PD can be non-null, but not both. 238 static Handle find_java_mirror_for_type(Symbol* signature, 239 Klass* accessing_klass, 240 Handle class_loader, 241 Handle protection_domain, 242 SignatureStream::FailureMode failure_mode, 243 TRAPS); 244 static Handle find_java_mirror_for_type(Symbol* signature, 245 Klass* accessing_klass, 246 SignatureStream::FailureMode failure_mode, 247 TRAPS) { 248 // callee will fill in CL/PD from AK, if they are needed 249 return find_java_mirror_for_type(signature, accessing_klass, Handle(), Handle(), 250 failure_mode, THREAD); 251 } 252 253 // find a java.lang.invoke.MethodType object for a given signature 254 // (asks Java to compute it if necessary, except in a compiler thread) 255 static Handle find_method_handle_type(Symbol* signature, 256 Klass* accessing_klass, 257 TRAPS); 258 259 // find a java.lang.Class object for a given signature 260 static Handle find_field_handle_type(Symbol* signature, 261 Klass* accessing_klass, 262 TRAPS); 263 264 // ask Java to compute a java.lang.invoke.MethodHandle object for a given CP entry 265 static Handle link_method_handle_constant(Klass* caller, 266 int ref_kind, //e.g., JVM_REF_invokeVirtual 267 Klass* callee, 268 Symbol* name, 269 Symbol* signature, 270 TRAPS); 271 272 // ask Java to compute a constant by invoking a BSM given a Dynamic_info CP entry 273 static void invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS); 274 275 // Record the error when the first attempt to resolve a reference from a constant 276 // pool entry to a class fails. 277 static void add_resolution_error(const constantPoolHandle& pool, int which, 278 Symbol* error, const char* message, 279 Symbol* cause = nullptr, const char* cause_msg = nullptr); 280 static void delete_resolution_error(ConstantPool* pool); 281 static Symbol* find_resolution_error(const constantPoolHandle& pool, int which, 282 const char** message, 283 Symbol** cause, const char** cause_msg); 284 285 // Record a nest host resolution/validation error 286 static void add_nest_host_error(const constantPoolHandle& pool, int which, 287 const char* message); 288 static const char* find_nest_host_error(const constantPoolHandle& pool, int which); 289 290 protected: 291 static InstanceKlass* _well_known_klasses[]; 292 293 private: 294 // table of box klasses (int_klass, etc.) 295 static InstanceKlass* _box_klasses[T_VOID+1]; 296 297 static OopHandle _java_system_loader; 298 static OopHandle _java_platform_loader; 299 300 private: 301 // Basic loading operations 302 static InstanceKlass* resolve_instance_class_or_null(Symbol* class_name, 303 Handle class_loader, 304 Handle protection_domain, TRAPS); 305 static Klass* resolve_array_class_or_null(Symbol* class_name, 306 Handle class_loader, 307 Handle protection_domain, TRAPS); 308 static void define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS); 309 static InstanceKlass* find_or_define_helper(Symbol* class_name, 310 Handle class_loader, 311 InstanceKlass* k, TRAPS); 312 static InstanceKlass* load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS); 313 static InstanceKlass* load_instance_class(Symbol* class_name, 314 Handle class_loader, TRAPS); 315 316 // Class loader constraints 317 static void check_constraints(InstanceKlass* k, ClassLoaderData* loader, 318 bool defining, TRAPS); 319 static void update_dictionary(JavaThread* current, InstanceKlass* k, ClassLoaderData* loader_data); 320 321 static bool is_shared_class_visible(Symbol* class_name, InstanceKlass* ik, 322 PackageEntry* pkg_entry, 323 Handle class_loader); 324 static bool is_shared_class_visible_impl(Symbol* class_name, 325 InstanceKlass* ik, 326 PackageEntry* pkg_entry, 327 Handle class_loader); 328 static bool check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super, 329 Handle class_loader, Handle protection_domain, 330 bool is_superclass, TRAPS); 331 static bool check_shared_class_super_types(InstanceKlass* ik, Handle class_loader, 332 Handle protection_domain, TRAPS); 333 // Second part of load_shared_class 334 static void load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) NOT_CDS_RETURN; 335 336 protected: 337 // Used by SystemDictionaryShared 338 339 static bool add_loader_constraint(Symbol* name, Klass* klass_being_linked, Handle loader1, 340 Handle loader2); 341 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld); 342 static InstanceKlass* load_shared_lambda_proxy_class(InstanceKlass* ik, 343 Handle class_loader, 344 Handle protection_domain, 345 PackageEntry* pkg_entry, 346 TRAPS); 347 static InstanceKlass* load_shared_class(InstanceKlass* ik, 348 Handle class_loader, 349 Handle protection_domain, 350 const ClassFileStream *cfs, 351 PackageEntry* pkg_entry, 352 TRAPS); 353 static Handle get_loader_lock_or_null(Handle class_loader); 354 static InstanceKlass* find_or_define_instance_class(Symbol* class_name, 355 Handle class_loader, 356 InstanceKlass* k, TRAPS); 357 public: 358 static bool is_system_class_loader(oop class_loader); 359 static bool is_platform_class_loader(oop class_loader); 360 static bool is_boot_class_loader(oop class_loader) { return class_loader == nullptr; } 361 static bool is_builtin_class_loader(oop class_loader) { 362 return is_boot_class_loader(class_loader) || 363 is_platform_class_loader(class_loader) || 364 is_system_class_loader(class_loader); 365 } 366 // Returns TRUE if the method is a non-public member of class java.lang.Object. 367 static bool is_nonpublic_Object_method(Method* m); 368 369 // Return Symbol or throw exception if name given is can not be a valid Symbol. 370 static Symbol* class_name_symbol(const char* name, Symbol* exception, TRAPS); 371 }; 372 373 #endif // SHARE_CLASSFILE_SYSTEMDICTIONARY_HPP