1 /*
   2  * Copyright (c) 2017, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #include <stdio.h>
  25 #include <string.h>
  26 #include "jvmti.h"
  27 
  28 #ifdef __cplusplus
  29 extern "C" {
  30 #endif
  31 
  32 #ifndef JNI_ENV_ARG
  33 
  34 #ifdef __cplusplus
  35 #define JNI_ENV_ARG(x, y) y
  36 #define JNI_ENV_PTR(x) x
  37 #else
  38 #define JNI_ENV_ARG(x,y) x, y
  39 #define JNI_ENV_PTR(x) (*x)
  40 #endif
  41 
  42 #endif
  43 
  44 #define TranslateError(err) "JVMTI error"
  45 
  46 #define PASSED 0
  47 #define FAILED 2
  48 
  49 static const char *EXC_CNAME = "java/lang/Exception";
  50 
  51 static jvmtiEnv *jvmti = NULL;
  52 static jint result = PASSED;
  53 
  54 static jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved);
  55 
  56 JNIEXPORT
  57 jint JNICALL Agent_OnLoad(JavaVM *jvm, char *options, void *reserved) {
  58     return Agent_Initialize(jvm, options, reserved);
  59 }
  60 
  61 JNIEXPORT
  62 jint JNICALL Agent_OnAttach(JavaVM *jvm, char *options, void *reserved) {
  63     return Agent_Initialize(jvm, options, reserved);
  64 }
  65 
  66 JNIEXPORT
  67 jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved) {
  68     return JNI_VERSION_1_8;
  69 }
  70 
  71 static
  72 jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved) {
  73     jvmtiCapabilities capabilities;
  74     jint res = JNI_ENV_PTR(jvm)->GetEnv(JNI_ENV_ARG(jvm, (void **) &jvmti),
  75                                         JVMTI_VERSION);
  76     if (res != JNI_OK || jvmti == NULL) {
  77         printf("    Error: wrong result of a valid call to GetEnv!\n");
  78         return JNI_ERR;
  79     }
  80 
  81     (void)memset(&capabilities, 0, sizeof(capabilities));
  82     capabilities.can_tag_objects = 1;
  83     capabilities.can_generate_garbage_collection_events = 1;
  84     (*jvmti)->AddCapabilities(jvmti, &capabilities);
  85 
  86     return JNI_OK;
  87 }
  88 
  89 static
  90 void throw_exc(JNIEnv *env, char *msg) {
  91     jclass exc_class = JNI_ENV_PTR(env)->FindClass(JNI_ENV_ARG(env, EXC_CNAME));
  92     jint rt = JNI_OK;
  93 
  94     if (exc_class == NULL) {
  95         printf("throw_exc: Error in FindClass(env, %s)\n", EXC_CNAME);
  96         return;
  97     }
  98     rt = JNI_ENV_PTR(env)->ThrowNew(JNI_ENV_ARG(env, exc_class), msg);
  99     if (rt == JNI_ERR) {
 100         printf("throw_exc: Error in JNI ThrowNew(env, %s)\n", msg);
 101     }
 102 }
 103 
 104 static jint JNICALL heap_iter_callback(jlong class_tag,
 105                                jlong size,
 106                                jlong* tag_ptr,
 107                                jint length,
 108                                void* user_data) {
 109   (*((jint*)(user_data)))++;
 110   return JVMTI_VISIT_OBJECTS;
 111 }
 112 
 113 JNIEXPORT jint JNICALL
 114 Java_TestHeapDump_heapdump(JNIEnv *env, jclass cls, jclass filter_cls) {
 115     jvmtiHeapCallbacks callbacks;
 116     jint totalCount = 0;
 117     if (jvmti == NULL) {
 118         throw_exc(env, "JVMTI client was not properly loaded!\n");
 119         return 0;
 120     }
 121 
 122     (void)memset(&callbacks, 0, sizeof(callbacks));
 123     callbacks.heap_iteration_callback = &heap_iter_callback;
 124     (*jvmti)->IterateThroughHeap(jvmti, 0, filter_cls, &callbacks, (const void *)&totalCount);
 125     return totalCount;
 126 }
 127 
 128 #ifdef __cplusplus
 129 }
 130 #endif