1 /*
2 * Copyright (c) 2015, 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/cdsConfig.hpp"
26 #include "cds/filemap.hpp"
27 #include "classfile/classFileParser.hpp"
28 #include "classfile/classFileStream.hpp"
29 #include "classfile/classLoader.hpp"
30 #include "classfile/classLoaderData.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoadInfo.hpp"
33 #include "classfile/klassFactory.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "prims/jvmtiEnvBase.hpp"
36 #include "prims/jvmtiRedefineClasses.hpp"
37 #include "runtime/handles.inline.hpp"
38 #include "utilities/macros.hpp"
39 #if INCLUDE_JFR
40 #include "jfr/support/jfrKlassExtension.hpp"
41 #endif
42
43
44 // called during initial loading of a shared class
45 InstanceKlass* KlassFactory::check_shared_class_file_load_hook(
46 InstanceKlass* ik,
47 Symbol* class_name,
48 Handle class_loader,
49 Handle protection_domain,
50 const ClassFileStream *cfs,
51 TRAPS) {
52 #if INCLUDE_CDS && INCLUDE_JVMTI
53 assert(ik != nullptr, "sanity");
54 assert(ik->is_shared(), "expecting a shared class");
55 if (JvmtiExport::should_post_class_file_load_hook()) {
56 ResourceMark rm(THREAD);
57 // Post the CFLH
58 JvmtiCachedClassFileData* cached_class_file = nullptr;
59 if (cfs == nullptr) {
60 cfs = FileMapInfo::open_stream_for_jvmti(ik, class_loader, CHECK_NULL);
61 }
62 unsigned char* ptr = (unsigned char*)cfs->buffer();
63 unsigned char* end_ptr = ptr + cfs->length();
64 unsigned char* old_ptr = ptr;
65 JvmtiExport::post_class_file_load_hook(class_name,
66 class_loader,
67 protection_domain,
68 &ptr,
69 &end_ptr,
70 &cached_class_file);
71 if (old_ptr != ptr) {
72 // JVMTI agent has modified class file data.
73 // Set new class file stream using JVMTI agent modified class file data.
74 ClassLoaderData* loader_data =
75 ClassLoaderData::class_loader_data(class_loader());
76 s2 path_index = ik->shared_classpath_index();
77 ClassFileStream* stream = new ClassFileStream(ptr,
78 pointer_delta_as_int(end_ptr, ptr),
79 cfs->source());
80 ClassLoadInfo cl_info(protection_domain);
81 ClassFileParser parser(stream,
82 class_name,
83 loader_data,
84 &cl_info,
85 ClassFileParser::BROADCAST, // publicity level
86 CHECK_NULL);
87 const ClassInstanceInfo* cl_inst_info = cl_info.class_hidden_info_ptr();
88 InstanceKlass* new_ik = parser.create_instance_klass(true, // changed_by_loadhook
89 *cl_inst_info, // dynamic_nest_host and classData
90 CHECK_NULL);
91
92 if (cached_class_file != nullptr) {
93 new_ik->set_cached_class_file(cached_class_file);
94 }
95
96 if (class_loader.is_null()) {
97 new_ik->set_classpath_index(path_index);
98 new_ik->assign_class_loader_type();
99 }
100
101 return new_ik;
102 }
103 }
104 #endif
105
106 return nullptr;
107 }
108
109
110 static ClassFileStream* check_class_file_load_hook(ClassFileStream* stream,
111 Symbol* name,
112 ClassLoaderData* loader_data,
113 Handle protection_domain,
114 JvmtiCachedClassFileData** cached_class_file,
115 TRAPS) {
116
117 assert(stream != nullptr, "invariant");
118
119 if (JvmtiExport::should_post_class_file_load_hook()) {
120 const JavaThread* jt = THREAD;
121
122 Handle class_loader(THREAD, loader_data->class_loader());
123
124 // Get the cached class file bytes (if any) from the class that
125 // is being retransformed. If class file load hook provides
126 // modified class data during class loading or redefinition,
127 // new cached class file buffer should be allocated.
128 // We use jvmti_thread_state()
129 // instead of JvmtiThreadState::state_for(jt) so we don't allocate
130 // a JvmtiThreadState any earlier than necessary. This will help
131 // avoid the bug described by 7126851.
132
133 JvmtiThreadState* state = jt->jvmti_thread_state();
134
135 if (state != nullptr) {
136 Klass* k = state->get_class_being_redefined();
137 if (k != nullptr && state->get_class_load_kind() == jvmti_class_load_kind_retransform) {
138 InstanceKlass* class_being_redefined = InstanceKlass::cast(k);
139 *cached_class_file = class_being_redefined->get_cached_class_file();
140 }
141 }
142
143 unsigned char* ptr = const_cast<unsigned char*>(stream->buffer());
144 unsigned char* end_ptr = ptr + stream->length();
145
146 JvmtiExport::post_class_file_load_hook(name,
147 class_loader,
148 protection_domain,
149 &ptr,
150 &end_ptr,
151 cached_class_file);
152
153 if (ptr != stream->buffer()) {
154 // JVMTI agent has modified class file data.
155 // Set new class file stream using JVMTI agent modified class file data.
156 stream = new ClassFileStream(ptr,
157 pointer_delta_as_int(end_ptr, ptr),
158 stream->source());
159 }
160 }
161
162 return stream;
163 }
164
165
166 InstanceKlass* KlassFactory::create_from_stream(ClassFileStream* stream,
167 Symbol* name,
168 ClassLoaderData* loader_data,
169 const ClassLoadInfo& cl_info,
170 TRAPS) {
171 assert(stream != nullptr, "invariant");
172 assert(loader_data != nullptr, "invariant");
173
174 ResourceMark rm(THREAD);
175 HandleMark hm(THREAD);
176
177 JvmtiCachedClassFileData* cached_class_file = nullptr;
178
179 ClassFileStream* old_stream = stream;
180
181 // increment counter
182 THREAD->statistical_info().incr_define_class_count();
183
184 // Skip this processing for VM hidden classes
185 if (!cl_info.is_hidden()) {
186 stream = check_class_file_load_hook(stream,
187 name,
188 loader_data,
189 cl_info.protection_domain(),
190 &cached_class_file,
191 CHECK_NULL);
192 }
193
194 ClassFileParser parser(stream,
195 name,
196 loader_data,
197 &cl_info,
198 ClassFileParser::BROADCAST, // publicity level
199 CHECK_NULL);
200
201 const ClassInstanceInfo* cl_inst_info = cl_info.class_hidden_info_ptr();
202 InstanceKlass* result = parser.create_instance_klass(old_stream != stream, *cl_inst_info, CHECK_NULL);
203 assert(result != nullptr, "result cannot be null with no pending exception");
204
205 if (cached_class_file != nullptr) {
206 // JVMTI: we have an InstanceKlass now, tell it about the cached bytes
207 result->set_cached_class_file(cached_class_file);
208 }
209
210 JFR_ONLY(ON_KLASS_CREATION(result, parser, THREAD);)
211
212 #if INCLUDE_CDS
213 if (CDSConfig::is_dumping_archive()) {
214 ClassLoader::record_result(THREAD, result, stream, old_stream != stream);
215 }
216 #endif // INCLUDE_CDS
217
218 return result;
219 }