1 /*
2 * Copyright (c) 1997, 2024, 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 PackageEntry;
74 class GCTimer;
75 class EventClassLoad;
76 class Symbol;
77
78 class SystemDictionary : AllStatic {
79 friend class BootstrapInfo;
80 friend class vmClasses;
81 friend class VMStructs;
82
83 public:
84
85 // Returns a class with a given class name and class loader. Loads the
86 // class if needed. If not found a NoClassDefFoundError or a
87 // ClassNotFoundException is thrown, depending on the value on the
88 // throw_error flag. For most uses the throw_error argument should be set
89 // to true.
90
91 static Klass* resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS);
92 // Convenient call for null loader and protection domain.
93 static Klass* resolve_or_fail(Symbol* class_name, bool throw_error, TRAPS) {
94 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
95 }
96
97 // Returns a class with a given class name and class loader.
98 // Loads the class if needed. If not found null is returned.
99 static Klass* resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS);
100 // Version with null loader and protection domain
101 static Klass* resolve_or_null(Symbol* class_name, TRAPS) {
102 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
103 }
104
105 static InstanceKlass* resolve_with_circularity_detection(Symbol* class_name,
106 Symbol* next_name,
107 Handle class_loader,
108 Handle protection_domain,
109 bool is_superclass,
110 TRAPS);
111
112 // Resolve a superclass or superinterface. Called from ClassFileParser,
113 // parse_interfaces, resolve_instance_class_or_null, load_shared_class
114 // "class_name" is the class whose super class or interface is being resolved.
115 static InstanceKlass* resolve_super_or_fail(Symbol* class_name, Symbol* super_name,
116 Handle class_loader,
117 Handle protection_domain, bool is_superclass, TRAPS) {
118 return resolve_with_circularity_detection(class_name, super_name, class_loader, protection_domain,
119 is_superclass, THREAD);
120 }
121
122 private:
123 // Parse the stream to create a hidden class.
124 // Used by jvm_lookup_define_class.
125 static InstanceKlass* resolve_hidden_class_from_stream(ClassFileStream* st,
126 Symbol* class_name,
127 Handle class_loader,
128 const ClassLoadInfo& cl_info,
129 TRAPS);
130
131 // Resolve a class from stream (called by jni_DefineClass and JVM_DefineClass)
132 // This class is added to the SystemDictionary.
133 static InstanceKlass* resolve_class_from_stream(ClassFileStream* st,
134 Symbol* class_name,
135 Handle class_loader,
136 const ClassLoadInfo& cl_info,
137 TRAPS);
138
139 static oop get_system_class_loader_impl(TRAPS);
140 static oop get_platform_class_loader_impl(TRAPS);
141
142 public:
143 // Resolve either a hidden or normal class from a stream of bytes, based on ClassLoadInfo
144 static InstanceKlass* resolve_from_stream(ClassFileStream* st,
145 Symbol* class_name,
146 Handle class_loader,
147 const ClassLoadInfo& cl_info,
148 TRAPS);
149
150 // Lookup an already loaded class. If not found null is returned.
151 static InstanceKlass* find_instance_klass(Thread* current, Symbol* class_name,
152 Handle class_loader, Handle protection_domain);
153
154 // Lookup an already loaded instance or array class.
155 // Do not make any queries to class loaders; consult only the cache.
156 // If not found null is returned.
157 static Klass* find_instance_or_array_klass(Thread* current, Symbol* class_name,
158 Handle class_loader,
159 Handle protection_domain);
160
161 // Lookup an instance or array class that has already been loaded
162 // either into the given class loader, or else into another class
163 // loader that is constrained (via loader constraints) to produce
164 // a consistent class. Do not take protection domains into account.
165 // Do not make any queries to class loaders; consult only the cache.
166 // Return null if the class is not found.
167 //
168 // This function is a strict superset of find_instance_or_array_klass.
169 // This function (the unchecked version) makes a conservative prediction
170 // of the result of the checked version, assuming successful lookup.
171 // If both functions return non-null, they must return the same value.
172 // Also, the unchecked version may sometimes be non-null where the
173 // checked version is null. This can occur in several ways:
174 // 1. No query has yet been made to the class loader.
175 // 2. The class loader was queried, but chose not to delegate.
176 // 3. ClassLoader.checkPackageAccess rejected a proposed protection domain.
177 // 4. Loading was attempted, but there was a linkage error of some sort.
178 // In all of these cases, the loader constraints on this type are
179 // satisfied, and it is safe for classes in the given class loader
180 // to manipulate strongly-typed values of the found class, subject
181 // to local linkage and access checks.
182 static Klass* find_constrained_instance_or_array_klass(Thread* current,
183 Symbol* class_name,
184 Handle class_loader);
185
186 static void classes_do(MetaspaceClosure* it);
187 // Iterate over all methods in all klasses
188 // Will not keep metadata alive. See ClassLoaderDataGraph::methods_do.
189 static void methods_do(void f(Method*));
190
191 // Garbage collection support
192
193 // Unload (that is, break root links to) all unmarked classes and
194 // loaders. Returns "true" iff something was unloaded.
195 static bool do_unloading(GCTimer* gc_timer);
196
197 // Printing
198 static void print();
199 static void print_on(outputStream* st);
200 static void dump(outputStream* st, bool verbose);
201
202 // Verification
203 static void verify();
204
205 // Initialization
206 static void initialize(TRAPS);
207
208 public:
209 // Returns java system loader
210 static oop java_system_loader();
211
212 // Returns java platform loader
213 static oop java_platform_loader();
214
215 // Compute the java system and platform loaders
216 static void compute_java_loaders(TRAPS);
217
218 // Register a new class loader
219 static ClassLoaderData* register_loader(Handle class_loader, bool create_mirror_cld = false);
220
221 static void set_system_loader(ClassLoaderData *cld);
222 static void set_platform_loader(ClassLoaderData *cld);
223
224 static Symbol* check_signature_loaders(Symbol* signature, Klass* klass_being_linked,
225 Handle loader1, Handle loader2, bool is_method);
226
227 // JSR 292
228 // find a java.lang.invoke.MethodHandle.invoke* method for a given signature
229 // (asks Java to compute it if necessary, except in a compiler thread)
230 static Method* find_method_handle_invoker(Klass* klass,
231 Symbol* name,
232 Symbol* signature,
233 Klass* accessing_klass,
234 Handle *appendix_result,
235 TRAPS);
236 // for a given signature, find the internal MethodHandle method (linkTo* or invokeBasic)
237 // (does not ask Java, since this is a low-level intrinsic defined by the JVM)
238 static Method* find_method_handle_intrinsic(vmIntrinsicID iid,
239 Symbol* signature,
240 TRAPS);
241
242 // compute java_mirror (java.lang.Class instance) for a type ("I", "[[B", "LFoo;", etc.)
243 // Either the accessing_klass or the CL/PD can be non-null, but not both.
244 static Handle find_java_mirror_for_type(Symbol* signature,
245 Klass* accessing_klass,
246 Handle class_loader,
247 Handle protection_domain,
248 SignatureStream::FailureMode failure_mode,
249 TRAPS);
250 static Handle find_java_mirror_for_type(Symbol* signature,
251 Klass* accessing_klass,
252 SignatureStream::FailureMode failure_mode,
253 TRAPS) {
254 // callee will fill in CL/PD from AK, if they are needed
255 return find_java_mirror_for_type(signature, accessing_klass, Handle(), Handle(),
256 failure_mode, THREAD);
257 }
258
259 // find a java.lang.invoke.MethodType object for a given signature
260 // (asks Java to compute it if necessary, except in a compiler thread)
261 static Handle find_method_handle_type(Symbol* signature,
262 Klass* accessing_klass,
263 TRAPS);
264
265 // find a java.lang.Class object for a given signature
266 static Handle find_field_handle_type(Symbol* signature,
267 Klass* accessing_klass,
268 TRAPS);
269
270 // ask Java to compute a java.lang.invoke.MethodHandle object for a given CP entry
271 static Handle link_method_handle_constant(Klass* caller,
272 int ref_kind, //e.g., JVM_REF_invokeVirtual
273 Klass* callee,
274 Symbol* name,
275 Symbol* signature,
276 TRAPS);
277
278 // ask Java to compute a constant by invoking a BSM given a Dynamic_info CP entry
279 static void invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS);
280
281 // Record the error when the first attempt to resolve a reference from a constant
282 // pool entry to a class fails.
283 static void add_resolution_error(const constantPoolHandle& pool, int which,
284 Symbol* error, const char* message,
285 Symbol* cause = nullptr, const char* cause_msg = nullptr);
286 static void delete_resolution_error(ConstantPool* pool);
287 static Symbol* find_resolution_error(const constantPoolHandle& pool, int which,
288 const char** message,
289 Symbol** cause, const char** cause_msg);
290
291 // Record a nest host resolution/validation error
292 static void add_nest_host_error(const constantPoolHandle& pool, int which,
293 const char* message);
294 static const char* find_nest_host_error(const constantPoolHandle& pool, int which);
295
296 static OopHandle _java_system_loader;
297 static OopHandle _java_platform_loader;
298
299 private:
300 // Basic loading operations
301 static InstanceKlass* resolve_instance_class_or_null(Symbol* class_name,
302 Handle class_loader,
303 Handle protection_domain, TRAPS);
304 static Klass* resolve_array_class_or_null(Symbol* class_name,
305 Handle class_loader,
306 Handle protection_domain, TRAPS);
307 static void define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS);
308 static InstanceKlass* find_or_define_helper(Symbol* class_name,
309 Handle class_loader,
310 InstanceKlass* k, TRAPS);
311 static InstanceKlass* load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS);
312 static InstanceKlass* load_instance_class(Symbol* class_name,
313 Handle class_loader, TRAPS);
314
315 // Class loader constraints
316 static void check_constraints(InstanceKlass* k, ClassLoaderData* loader,
317 bool defining, TRAPS);
318 static void update_dictionary(JavaThread* current, InstanceKlass* k, ClassLoaderData* loader_data);
319
320 static bool is_shared_class_visible(Symbol* class_name, InstanceKlass* ik,
321 PackageEntry* pkg_entry,
322 Handle class_loader);
323 static bool is_shared_class_visible_impl(Symbol* class_name,
324 InstanceKlass* ik,
325 PackageEntry* pkg_entry,
326 Handle class_loader);
327 static bool check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super,
328 Handle class_loader, Handle protection_domain,
329 bool is_superclass, TRAPS);
330 static bool check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
331 Handle protection_domain, TRAPS);
332 // Second part of load_shared_class
333 static void load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) NOT_CDS_RETURN;
334
335 protected:
336 // Used by SystemDictionaryShared
337
338 static bool add_loader_constraint(Symbol* name, Klass* klass_being_linked, Handle loader1,
339 Handle loader2);
340 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld);
341 static InstanceKlass* load_shared_lambda_proxy_class(InstanceKlass* ik,
342 Handle class_loader,
343 Handle protection_domain,
344 PackageEntry* pkg_entry,
345 TRAPS);
346 static InstanceKlass* load_shared_class(InstanceKlass* ik,
347 Handle class_loader,
348 Handle protection_domain,
349 const ClassFileStream *cfs,
350 PackageEntry* pkg_entry,
351 TRAPS);
352 static Handle get_loader_lock_or_null(Handle class_loader);
353 static InstanceKlass* find_or_define_instance_class(Symbol* class_name,
354 Handle class_loader,
355 InstanceKlass* k, TRAPS);
356 public:
357 static bool is_system_class_loader(oop class_loader);
358 static bool is_platform_class_loader(oop class_loader);
359 static bool is_boot_class_loader(oop class_loader) { return class_loader == nullptr; }
360 static bool is_builtin_class_loader(oop class_loader) {
361 return is_boot_class_loader(class_loader) ||
362 is_platform_class_loader(class_loader) ||
363 is_system_class_loader(class_loader);
364 }
365 // Returns TRUE if the method is a non-public member of class java.lang.Object.
366 static bool is_nonpublic_Object_method(Method* m);
367
368 // Return Symbol or throw exception if name given is can not be a valid Symbol.
369 static Symbol* class_name_symbol(const char* name, Symbol* exception, TRAPS);
370 };
371
372 #endif // SHARE_CLASSFILE_SYSTEMDICTIONARY_HPP