1 /*

     2  * Copyright (c) 2017, 2018, 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_9);

    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