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/cds_globals.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/filemap.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.hpp"
32 #include "classfile/classLoaderData.inline.hpp"
33 #include "classfile/classLoadInfo.hpp"
34 #include "classfile/klassFactory.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 new_ik->assign_class_loader_type();
102 }
103
104 return new_ik;
105 }
106 }
107 #endif
108
109 return nullptr;
110 }
111
112
113 static ClassFileStream* check_class_file_load_hook(ClassFileStream* stream,
114 Symbol* name,
115 ClassLoaderData* loader_data,
116 Handle protection_domain,
117 JvmtiCachedClassFileData** cached_class_file,
118 TRAPS) {
119
120 assert(stream != nullptr, "invariant");
121
122 if (JvmtiExport::should_post_class_file_load_hook()) {
123 const JavaThread* jt = THREAD;
124
125 Handle class_loader(THREAD, loader_data->class_loader());
126
127 // Get the cached class file bytes (if any) from the class that
128 // is being retransformed. If class file load hook provides
129 // modified class data during class loading or redefinition,
130 // new cached class file buffer should be allocated.
131 // We use jvmti_thread_state()
132 // instead of JvmtiThreadState::state_for(jt) so we don't allocate
133 // a JvmtiThreadState any earlier than necessary. This will help
134 // avoid the bug described by 7126851.
135
136 JvmtiThreadState* state = jt->jvmti_thread_state();
137
138 if (state != nullptr) {
139 Klass* k = state->get_class_being_redefined();
140 if (k != nullptr && state->get_class_load_kind() == jvmti_class_load_kind_retransform) {
141 InstanceKlass* class_being_redefined = InstanceKlass::cast(k);
142 *cached_class_file = class_being_redefined->get_cached_class_file();
143 }
144 }
145
146 unsigned char* ptr = const_cast<unsigned char*>(stream->buffer());
147 unsigned char* end_ptr = ptr + stream->length();
148
149 JvmtiExport::post_class_file_load_hook(name,
150 class_loader,
151 protection_domain,
152 &ptr,
153 &end_ptr,
154 cached_class_file);
155
156 if (ptr != stream->buffer()) {
157 // JVMTI agent has modified class file data.
158 // Set new class file stream using JVMTI agent modified class file data.
159 stream = new ClassFileStream(ptr,
160 pointer_delta_as_int(end_ptr, ptr),
161 stream->source(),
162 /* from_boot_loader_modules_image */ false,
163 /* from_class_file_load_hook */ true);
164 }
165 }
166
167 return stream;
168 }
169
170
171 InstanceKlass* KlassFactory::create_from_stream(ClassFileStream* stream,
172 Symbol* name,
173 ClassLoaderData* loader_data,
174 const ClassLoadInfo& cl_info,
175 TRAPS) {
176 assert(stream != nullptr, "invariant");
177 assert(loader_data != nullptr, "invariant");
178
179 ResourceMark rm(THREAD);
180 HandleMark hm(THREAD);
181
182 JvmtiCachedClassFileData* cached_class_file = nullptr;
183
184 ClassFileStream* old_stream = stream;
185
186 // increment counter
187 THREAD->statistical_info().incr_define_class_count();
188
189 // Skip this processing for VM hidden classes
190 if (!cl_info.is_hidden()) {
191 stream = check_class_file_load_hook(stream,
192 name,
193 loader_data,
194 cl_info.protection_domain(),
195 &cached_class_file,
196 CHECK_NULL);
197 }
198
199 ClassFileParser parser(stream,
200 name,
201 loader_data,
202 &cl_info,
203 ClassFileParser::BROADCAST, // publicity level
204 CHECK_NULL);
205
206 const ClassInstanceInfo* cl_inst_info = cl_info.class_hidden_info_ptr();
207 InstanceKlass* result = parser.create_instance_klass(old_stream != stream, *cl_inst_info, CHECK_NULL);
208 assert(result != nullptr, "result cannot be null with no pending exception");
209
210 if (cached_class_file != nullptr) {
211 // JVMTI: we have an InstanceKlass now, tell it about the cached bytes
212 result->set_cached_class_file(cached_class_file);
213 }
214
215 JFR_ONLY(ON_KLASS_CREATION(result, parser, THREAD);)
216
217 #if INCLUDE_CDS
218 if (CDSConfig::is_dumping_archive()) {
219 ClassLoader::record_result(THREAD, result, stream, old_stream != stream);
220 }
221 #endif // INCLUDE_CDS
222
223 return result;
224 }