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   return JNI_OK;
45 }
46 
47 JNIEXPORT jboolean JNICALL
48 Java_ValueGetClassFields_nTestGetClassFields(JNIEnv *jni, jclass thisClass, jclass cls, jint fieldNum) {
49   bool result = true;
50   jint field_count;
51   jfieldID* fields = nullptr;
52   check_jvmti_error(jvmti->GetClassFields(cls, &field_count, &fields), "GetClassFields");
53 
54   if (field_count != fieldNum) {
55     LOG("ERROR: GetClassFields returned unexpected field count: %d (expected %d)\n", (int)field_count, (int)fieldNum);
56     result = false;
57   } else {
58     // Use GetFieldName to verify correctness of the returned fields.
59     for (jint i = 0; i < field_count; i++) {
60       char *name = nullptr;
61       char *signature = nullptr;
62 
63       check_jvmti_error(jvmti->GetFieldName(cls, fields[i], &name, &signature, nullptr), "GetFieldName");
64 
65       LOG(" - field %s, sig = %s\n", name, signature);
66       jvmti->Deallocate((unsigned char *)name);
67       jvmti->Deallocate((unsigned char *)signature);
68     }
69   }
70 
71   jvmti->Deallocate((unsigned char *)fields);
72   return result ? JNI_TRUE : JNI_FALSE;
73 }
74 
75 #ifdef __cplusplus
76 }
77 #endif
78