1 /*
2 * Copyright (c) 2024, 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 #include <stdio.h>
25 #include <string.h>
26 #include "jvmti.h"
27 #include "jni.h"
28 #include "jvmti_common.hpp"
29
30 #ifdef __cplusplus
31 extern "C" {
32 #endif
33
34 static jvmtiEnv *jvmti = nullptr;
35
36
37 JNIEXPORT jint JNICALL
38 Agent_OnLoad(JavaVM *jvm, char *options, void *reserved) {
39 jint res = jvm->GetEnv((void **) &jvmti, JVMTI_VERSION_1_1);
40 if (res != JNI_OK || jvmti == nullptr) {
41 LOG("GetEnv failed, res = %d", (int)res);
42 return JNI_ERR;
43 }
44
45 jvmtiCapabilities caps;
46 memset(&caps, 0, sizeof(caps));
47 caps.can_access_local_variables = 1;
48 jvmtiError err = jvmti->AddCapabilities(&caps);
49 if (err != JVMTI_ERROR_NONE) {
50 LOG("AddCapabilities failed: %s (%d)\n", TranslateError(err), err);
51 return JNI_ERR;
52 }
53
54 return JNI_OK;
55 }
56
57 static void log_value(JNIEnv *jni, jobject value) {
58 jclass cls = jni->GetObjectClass(value);
59 if (cls == nullptr) {
60 LOG("ERROR: value class is NULL\n");
61 return;
62 }
63
64 char* sig = nullptr;
65 check_jvmti_error(jvmti->GetClassSignature(cls, &sig, nullptr), "GetClassSignature");
66
67 LOG(" - the value class: %s\n", sig);
68 jvmti->Deallocate((unsigned char *)sig);
69 }
70
71 static jobject get_local(JNIEnv *jni, jthread thread, jint depth, jint slot) {
72 LOG("GetLocalObject for slot %d...\n", (int)slot);
73 jobject value = nullptr;
74 check_jvmti_error(jvmti->GetLocalObject(thread, depth, slot, &value), "GetLocalObject");
75
76 log_value(jni, value);
77
78 return value;
79 }
80
81 static void set_local(jthread thread, jint depth, jint slot, jobject value) {
82 LOG("SetLocalObject for slot %d...\n", (int)slot);
83 check_jvmti_error(jvmti->SetLocalObject(thread, depth, slot, value), "SetLocalObject");
84 }
85
86 static jobject get_this(JNIEnv *jni, jthread thread, jint depth) {
87 LOG("GetLocalInstance...\n");
88 jobject value = nullptr;
89 check_jvmti_error(jvmti->GetLocalInstance(thread, depth, &value), "GetLocalInstance");
90
91 log_value(jni, value);
92
93 return value;
94 }
95
96 JNIEXPORT jboolean JNICALL
97 Java_ValueGetSetLocal_nTestLocals(JNIEnv *jni, jclass thisClass, jthread thread) {
98 bool result = true;
99 const jint depth = 1;
100
101 jobject obj0 = get_local(jni, thread, depth, 0);
102 jobject obj1 = get_local(jni, thread, depth, 1);
103 jobject obj2 = get_local(jni, thread, depth, 2);
104 jobject obj3 = get_local(jni, thread, depth, 3);
105 jobject obj_this = get_this(jni, thread, depth);
106
107 // obj0 is expected to be equal "this"
108 if (!jni->IsSameObject(obj0, obj_this)) {
109 LOG("ERROR: obj0 != obj_this\n");
110 result = false;
111 }
112 // obj3 is expected to be equal obj2
113 if (!jni->IsSameObject(obj3, obj2)) {
114 LOG("ERROR: obj3 != obj2\n");
115 result = false;
116 }
117
118 // set obj3 = obj1
119 set_local(thread, depth, 3, obj1);
120
121 return result ? JNI_TRUE : JNI_FALSE;
122 }
123
124 #ifdef __cplusplus
125 }
126 #endif
127