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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 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 template <class E> class GrowableArray;
 79 
 80 class SystemDictionary : AllStatic {
 81   friend class BootstrapInfo;
 82   friend class ClassPrelinker;
 83   friend class vmClasses;
 84   friend class VMStructs;
 85 
 86  public:
 87 
 88   // Returns a class with a given class name and class loader.  Loads the
 89   // class if needed. If not found a NoClassDefFoundError or a
 90   // ClassNotFoundException is thrown, depending on the value on the
 91   // throw_error flag.  For most uses the throw_error argument should be set
 92   // to true.
 93 
 94   static Klass* resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS);
 95   // Convenient call for null loader and protection domain.
 96   static Klass* resolve_or_fail(Symbol* class_name, bool throw_error, TRAPS) {
 97     return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 98   }
 99 
100   // Returns a class with a given class name and class loader.
101   // Loads the class if needed. If not found null is returned.
102   static Klass* resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS);
103   // Version with null loader and protection domain
104   static Klass* resolve_or_null(Symbol* class_name, TRAPS) {
105     return resolve_or_null(class_name, Handle(), Handle(), THREAD);
106   }
107 
108   // Resolve a superclass or superinterface. Called from ClassFileParser,
109   // parse_interfaces, resolve_instance_class_or_null, load_shared_class
110   // "class_name" is the class whose super class or interface is being resolved.
111   static InstanceKlass* resolve_super_or_fail(Symbol* class_name,
112                                               Symbol* super_name,
113                                               Handle class_loader,
114                                               Handle protection_domain,
115                                               bool is_superclass,
116                                               TRAPS);
117  private:
118   // Parse the stream to create a hidden class.
119   // Used by jvm_lookup_define_class.
120   static InstanceKlass* resolve_hidden_class_from_stream(ClassFileStream* st,
121                                                          Symbol* class_name,
122                                                          Handle class_loader,
123                                                          const ClassLoadInfo& cl_info,
124                                                          TRAPS);
125 
126   // Resolve a class from stream (called by jni_DefineClass and JVM_DefineClass)
127   // This class is added to the SystemDictionary.
128   static InstanceKlass* resolve_class_from_stream(ClassFileStream* st,
129                                                   Symbol* class_name,
130                                                   Handle class_loader,
131                                                   const ClassLoadInfo& cl_info,
132                                                   TRAPS);
133 
134   static oop get_system_class_loader_impl(TRAPS);
135   static oop get_platform_class_loader_impl(TRAPS);
136 
137  public:
138   // Resolve either a hidden or normal class from a stream of bytes, based on ClassLoadInfo
139   static InstanceKlass* resolve_from_stream(ClassFileStream* st,
140                                             Symbol* class_name,
141                                             Handle class_loader,
142                                             const ClassLoadInfo& cl_info,
143                                             TRAPS);
144 
145   // Lookup an already loaded class. If not found null is returned.
146   static InstanceKlass* find_instance_klass(Thread* current, Symbol* class_name,
147                                             Handle class_loader, Handle protection_domain);
148 
149   // Lookup an already loaded instance or array class.
150   // Do not make any queries to class loaders; consult only the cache.
151   // If not found null is returned.
152   static Klass* find_instance_or_array_klass(Thread* current, Symbol* class_name,
153                                              Handle class_loader,
154                                              Handle protection_domain);
155 
156   // Lookup an instance or array class that has already been loaded
157   // either into the given class loader, or else into another class
158   // loader that is constrained (via loader constraints) to produce
159   // a consistent class.  Do not take protection domains into account.
160   // Do not make any queries to class loaders; consult only the cache.
161   // Return null if the class is not found.
162   //
163   // This function is a strict superset of find_instance_or_array_klass.
164   // This function (the unchecked version) makes a conservative prediction
165   // of the result of the checked version, assuming successful lookup.
166   // If both functions return non-null, they must return the same value.
167   // Also, the unchecked version may sometimes be non-null where the
168   // checked version is null.  This can occur in several ways:
169   //   1. No query has yet been made to the class loader.
170   //   2. The class loader was queried, but chose not to delegate.
171   //   3. ClassLoader.checkPackageAccess rejected a proposed protection domain.
172   //   4. Loading was attempted, but there was a linkage error of some sort.
173   // In all of these cases, the loader constraints on this type are
174   // satisfied, and it is safe for classes in the given class loader
175   // to manipulate strongly-typed values of the found class, subject
176   // to local linkage and access checks.
177   static Klass* find_constrained_instance_or_array_klass(Thread* current,
178                                                          Symbol* class_name,
179                                                          Handle class_loader);
180 
181   static void classes_do(MetaspaceClosure* it);
182   // Iterate over all methods in all klasses
183 
184   static void methods_do(void f(Method*));
185 
186   // Garbage collection support
187 
188   // Unload (that is, break root links to) all unmarked classes and
189   // loaders.  Returns "true" iff something was unloaded.
190   static bool do_unloading(GCTimer* gc_timer);
191 
192   // Printing
193   static void print();
194   static void print_on(outputStream* st);
195   static void dump(outputStream* st, bool verbose);
196 
197   // Verification
198   static void verify();
199 
200   // Initialization
201   static void initialize(TRAPS);
202 
203 public:
204   // Returns java system loader
205   static oop java_system_loader();
206 
207   // Returns java platform loader
208   static oop java_platform_loader();
209 
210   // Compute the java system and platform loaders
211   static void compute_java_loaders(TRAPS);
212 
213   // Register a new class loader
214   static ClassLoaderData* register_loader(Handle class_loader, bool create_mirror_cld = false);
215 
216   static void set_system_loader(ClassLoaderData *cld);
217   static void set_platform_loader(ClassLoaderData *cld);
218 
219   static Symbol* check_signature_loaders(Symbol* signature, Klass* klass_being_linked,
220                                          Handle loader1, Handle loader2, bool is_method);
221 
222   // JSR 292
223   // find a java.lang.invoke.MethodHandle.invoke* method for a given signature
224   // (asks Java to compute it if necessary, except in a compiler thread)
225   static Method* find_method_handle_invoker(Klass* klass,
226                                             Symbol* name,
227                                             Symbol* signature,
228                                             Klass* accessing_klass,
229                                             Handle *appendix_result,
230                                             TRAPS);
231   // for a given signature, find the internal MethodHandle method (linkTo* or invokeBasic)
232   // (does not ask Java, since this is a low-level intrinsic defined by the JVM)
233   static Method* find_method_handle_intrinsic(vmIntrinsicID iid,
234                                               Symbol* signature,
235                                               TRAPS);
236 
237   static void get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) NOT_CDS_RETURN;
238   static void restore_archived_method_handle_intrinsics() NOT_CDS_RETURN;
239 
240   // compute java_mirror (java.lang.Class instance) for a type ("I", "[[B", "LFoo;", etc.)
241   // Either the accessing_klass or the CL/PD can be non-null, but not both.
242   static Handle    find_java_mirror_for_type(Symbol* signature,
243                                              Klass* accessing_klass,
244                                              Handle class_loader,
245                                              Handle protection_domain,
246                                              SignatureStream::FailureMode failure_mode,
247                                              TRAPS);
248   static Handle    find_java_mirror_for_type(Symbol* signature,
249                                              Klass* accessing_klass,
250                                              SignatureStream::FailureMode failure_mode,
251                                              TRAPS) {
252     // callee will fill in CL/PD from AK, if they are needed
253     return find_java_mirror_for_type(signature, accessing_klass, Handle(), Handle(),
254                                      failure_mode, THREAD);
255   }
256 
257   // find a java.lang.invoke.MethodType object for a given signature
258   // (asks Java to compute it if necessary, except in a compiler thread)
259   static Handle    find_method_handle_type(Symbol* signature,
260                                            Klass* accessing_klass,
261                                            TRAPS);
262 
263   // find a java.lang.Class object for a given signature
264   static Handle    find_field_handle_type(Symbol* signature,
265                                           Klass* accessing_klass,
266                                           TRAPS);
267 
268   // ask Java to compute a java.lang.invoke.MethodHandle object for a given CP entry
269   static Handle    link_method_handle_constant(Klass* caller,
270                                                int ref_kind, //e.g., JVM_REF_invokeVirtual
271                                                Klass* callee,
272                                                Symbol* name,
273                                                Symbol* signature,
274                                                TRAPS);
275 
276   // ask Java to compute a constant by invoking a BSM given a Dynamic_info CP entry
277   static void      invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS);
278 
279   // Record the error when the first attempt to resolve a reference from a constant
280   // pool entry to a class fails.
281   static void add_resolution_error(const constantPoolHandle& pool, int which, Symbol* error,
282                                    Symbol* message, Symbol* cause = nullptr, Symbol* cause_msg = nullptr);
283   static void delete_resolution_error(ConstantPool* pool);
284   static Symbol* find_resolution_error(const constantPoolHandle& pool, int which,
285                                        Symbol** message, Symbol** cause, Symbol** cause_msg);
286 
287 
288   // Record a nest host resolution/validation error
289   static void add_nest_host_error(const constantPoolHandle& pool, int which,
290                                   const char* message);
291   static const char* find_nest_host_error(const constantPoolHandle& pool, int which);
292 
293   static void preload_class(JavaThread* current,  InstanceKlass* k,
294                             ClassLoaderData* loader_data) NOT_CDS_RETURN;
295 protected:
296   static InstanceKlass* _well_known_klasses[];
297 
298 private:
299   // table of box klasses (int_klass, etc.)
300   static InstanceKlass* _box_klasses[T_VOID+1];
301 
302   static OopHandle  _java_system_loader;
303   static OopHandle  _java_platform_loader;
304 
305 private:
306   // Basic loading operations
307   static InstanceKlass* resolve_instance_class_or_null(Symbol* class_name,
308                                                        Handle class_loader,
309                                                        Handle protection_domain, TRAPS);
310   static Klass* resolve_array_class_or_null(Symbol* class_name,
311                                             Handle class_loader,
312                                             Handle protection_domain, TRAPS);
313   static void define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS);
314   static InstanceKlass* find_or_define_helper(Symbol* class_name,
315                                               Handle class_loader,
316                                               InstanceKlass* k, TRAPS);
317   static InstanceKlass* load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS);
318   static InstanceKlass* load_instance_class(Symbol* class_name,
319                                             Handle class_loader, TRAPS);
320 
321   // Class loader constraints
322   static void check_constraints(InstanceKlass* k, ClassLoaderData* loader,
323                                 bool defining, TRAPS);
324   static void update_dictionary(JavaThread* current, InstanceKlass* k, ClassLoaderData* loader_data);
325 
326   static bool is_shared_class_visible(Symbol* class_name, InstanceKlass* ik,
327                                       PackageEntry* pkg_entry,
328                                       Handle class_loader);
329   static bool is_shared_class_visible_impl(Symbol* class_name,
330                                            InstanceKlass* ik,
331                                            PackageEntry* pkg_entry,
332                                            Handle class_loader);
333   static bool check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super,
334                                             Handle class_loader,  Handle protection_domain,
335                                             bool is_superclass, TRAPS);
336   static bool check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
337                                                Handle protection_domain, TRAPS);
338   static void restore_archived_method_handle_intrinsics_impl(TRAPS);
339 
340 protected:
341   // Used by SystemDictionaryShared
342 
343   // Second part of load_shared_class
344   static void load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) NOT_CDS_RETURN;
345 
346   static bool add_loader_constraint(Symbol* name, Klass* klass_being_linked,  Handle loader1,
347                                     Handle loader2);
348   static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld);
349   static InstanceKlass* load_shared_lambda_proxy_class(InstanceKlass* ik,
350                                                        Handle class_loader,
351                                                        Handle protection_domain,
352                                                        PackageEntry* pkg_entry,
353                                                        TRAPS);
354   static InstanceKlass* load_shared_class(InstanceKlass* ik,
355                                           Handle class_loader,
356                                           Handle protection_domain,
357                                           const ClassFileStream *cfs,
358                                           PackageEntry* pkg_entry,
359                                           TRAPS);
360   static Handle get_loader_lock_or_null(Handle class_loader);
361   static InstanceKlass* find_or_define_instance_class(Symbol* class_name,
362                                                       Handle class_loader,
363                                                       InstanceKlass* k, TRAPS);
364 public:
365   static bool is_system_class_loader(oop class_loader);
366   static bool is_platform_class_loader(oop class_loader);
367   static bool is_boot_class_loader(oop class_loader) { return class_loader == nullptr; }
368   static bool is_builtin_class_loader(oop class_loader) {
369     return is_boot_class_loader(class_loader)      ||
370            is_platform_class_loader(class_loader)  ||
371            is_system_class_loader(class_loader);
372   }
373   // Returns TRUE if the method is a non-public member of class java.lang.Object.
374   static bool is_nonpublic_Object_method(Method* m);
375 
376   // Return Symbol or throw exception if name given is can not be a valid Symbol.
377   static Symbol* class_name_symbol(const char* name, Symbol* exception, TRAPS);
378 };
379 
380 #endif // SHARE_CLASSFILE_SYSTEMDICTIONARY_HPP