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 "classfile/systemDictionaryShared.hpp"
35 #include "memory/resourceArea.hpp"
36 #include "prims/jvmtiEnvBase.hpp"
37 #include "prims/jvmtiRedefineClasses.hpp"
38 #include "runtime/handles.inline.hpp"
39 #include "utilities/macros.hpp"
40 #if INCLUDE_JFR
41 #include "jfr/support/jfrKlassExtension.hpp"
42 #endif
43
44
45 // called during initial loading of a shared class
46 InstanceKlass* KlassFactory::check_shared_class_file_load_hook(
47 InstanceKlass* ik,
48 Symbol* class_name,
49 Handle class_loader,
50 Handle protection_domain,
51 const ClassFileStream *cfs,
52 TRAPS) {
53 #if INCLUDE_CDS && INCLUDE_JVMTI
54 assert(ik != nullptr, "sanity");
55 assert(ik->is_shared(), "expecting a shared class");
56 if (JvmtiExport::should_post_class_file_load_hook()) {
57 ResourceMark rm(THREAD);
58 // Post the CFLH
59 JvmtiCachedClassFileData* cached_class_file = nullptr;
60 if (cfs == nullptr) {
61 cfs = FileMapInfo::open_stream_for_jvmti(ik, class_loader, CHECK_NULL);
62 }
63 unsigned char* ptr = (unsigned char*)cfs->buffer();
64 unsigned char* end_ptr = ptr + cfs->length();
65 unsigned char* old_ptr = ptr;
66 JvmtiExport::post_class_file_load_hook(class_name,
67 class_loader,
68 protection_domain,
69 &ptr,
70 &end_ptr,
71 &cached_class_file);
72 if (old_ptr != ptr) {
73 // JVMTI agent has modified class file data.
74 // Set new class file stream using JVMTI agent modified class file data.
75 ClassLoaderData* loader_data =
76 ClassLoaderData::class_loader_data(class_loader());
77 s2 path_index = ik->shared_classpath_index();
78 ClassFileStream* stream = new ClassFileStream(ptr,
79 pointer_delta_as_int(end_ptr, ptr),
80 cfs->source(),
81 /* from_boot_loader_modules_image */ false,
82 /* from_class_file_load_hook */ true);
83 ClassLoadInfo cl_info(protection_domain);
84 ClassFileParser parser(stream,
85 class_name,
86 loader_data,
87 &cl_info,
88 ClassFileParser::BROADCAST, // publicity level
89 CHECK_NULL);
90 const ClassInstanceInfo* cl_inst_info = cl_info.class_hidden_info_ptr();
91 InstanceKlass* new_ik = parser.create_instance_klass(true, // changed_by_loadhook
92 *cl_inst_info, // dynamic_nest_host and classData
93 CHECK_NULL);
94
95 if (cached_class_file != nullptr) {
96 new_ik->set_cached_class_file(cached_class_file);
97 }
98
99 if (class_loader.is_null()) {
100 new_ik->set_classpath_index(path_index);
101 }
102
103 return new_ik;
104 }
105 }
106 #endif
107
108 return nullptr;
109 }
110
111
112 static ClassFileStream* check_class_file_load_hook(ClassFileStream* stream,
113 Symbol* name,
114 ClassLoaderData* loader_data,
115 Handle protection_domain,
116 JvmtiCachedClassFileData** cached_class_file,
117 TRAPS) {
118
119 assert(stream != nullptr, "invariant");
120
121 if (JvmtiExport::should_post_class_file_load_hook()) {
122 const JavaThread* jt = THREAD;
123
124 Handle class_loader(THREAD, loader_data->class_loader());
125
126 // Get the cached class file bytes (if any) from the class that
127 // is being retransformed. If class file load hook provides
128 // modified class data during class loading or redefinition,
129 // new cached class file buffer should be allocated.
130 // We use jvmti_thread_state()
131 // instead of JvmtiThreadState::state_for(jt) so we don't allocate
132 // a JvmtiThreadState any earlier than necessary. This will help
133 // avoid the bug described by 7126851.
134
135 JvmtiThreadState* state = jt->jvmti_thread_state();
136
137 if (state != nullptr) {
138 Klass* k = state->get_class_being_redefined();
139 if (k != nullptr && state->get_class_load_kind() == jvmti_class_load_kind_retransform) {
140 InstanceKlass* class_being_redefined = InstanceKlass::cast(k);
141 *cached_class_file = class_being_redefined->get_cached_class_file();
142 }
143 }
144
145 unsigned char* ptr = const_cast<unsigned char*>(stream->buffer());
146 unsigned char* end_ptr = ptr + stream->length();
147
148 JvmtiExport::post_class_file_load_hook(name,
149 class_loader,
150 protection_domain,
151 &ptr,
152 &end_ptr,
153 cached_class_file);
154
155 if (ptr != stream->buffer()) {
156 // JVMTI agent has modified class file data.
157 // Set new class file stream using JVMTI agent modified class file data.
158 stream = new ClassFileStream(ptr,
159 pointer_delta_as_int(end_ptr, ptr),
160 stream->source(),
161 /* from_boot_loader_modules_image */ false,
162 /* from_class_file_load_hook */ true);
163 }
164 }
165
166 return stream;
167 }
168
169
170 InstanceKlass* KlassFactory::create_from_stream(ClassFileStream* stream,
171 Symbol* name,
172 ClassLoaderData* loader_data,
173 const ClassLoadInfo& cl_info,
174 TRAPS) {
175 assert(stream != nullptr, "invariant");
176 assert(loader_data != nullptr, "invariant");
177
178 ResourceMark rm(THREAD);
179 HandleMark hm(THREAD);
180
181 JvmtiCachedClassFileData* cached_class_file = nullptr;
182
183 ClassFileStream* old_stream = stream;
184
185 // increment counter
186 THREAD->statistical_info().incr_define_class_count();
187
188 // Skip this processing for VM hidden classes
189 if (!cl_info.is_hidden()) {
190 stream = check_class_file_load_hook(stream,
191 name,
192 loader_data,
193 cl_info.protection_domain(),
194 &cached_class_file,
195 CHECK_NULL);
196 }
197
198 ClassFileParser parser(stream,
199 name,
200 loader_data,
201 &cl_info,
202 ClassFileParser::BROADCAST, // publicity level
203 CHECK_NULL);
204
205 const ClassInstanceInfo* cl_inst_info = cl_info.class_hidden_info_ptr();
206 InstanceKlass* result = parser.create_instance_klass(old_stream != stream, *cl_inst_info, CHECK_NULL);
207 assert(result != nullptr, "result cannot be null with no pending exception");
208 if (CDSConfig::is_dumping_archive() && stream->from_class_file_load_hook()) {
209 SystemDictionaryShared::set_from_class_file_load_hook(result);
210 }
211
212 if (cached_class_file != nullptr) {
213 // JVMTI: we have an InstanceKlass now, tell it about the cached bytes
214 result->set_cached_class_file(cached_class_file);
215 }
216
217 JFR_ONLY(ON_KLASS_CREATION(result, parser, THREAD);)
218
219 #if INCLUDE_CDS
220 if (CDSConfig::is_dumping_archive()) {
221 ClassLoader::record_result(THREAD, result, stream, old_stream != stream);
222 }
223 #endif // INCLUDE_CDS
224
225 return result;
226 }