1 /*
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  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
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  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  *
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 18  *
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 20  * or visit www.oracle.com if you need additional information or have any
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 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