/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#include <string.h>
#include <jvmti.h>

static void JNICALL vm_init_callback(jvmtiEnv* jvmti_env, JNIEnv* jni_env, jthread thread)
{
    jclass cl = jni_env->FindClass("VMInit1/Status");
    if (NULL == cl)
        return;

    jfieldID fid = jni_env->GetStaticFieldID(cl, "status", "Z");
    if (NULL == fid)
        return;

    jni_env->SetStaticBooleanField(cl, fid, JNI_TRUE);
}

JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM *vm, char *options, void *reserved)
{
    jvmtiEnv *jvmti_env;
    if(vm->GetEnv((void**)&jvmti_env, JVMTI_VERSION_1_0) != JNI_OK)
        return JNI_ERR;

    // Get all supported capabilities
    jvmtiCapabilities capabilities;
    jvmtiError result = jvmti_env->GetPotentialCapabilities(&capabilities);
    if (JVMTI_ERROR_NONE != result)
        return JNI_ERR;

    // Enabled all supported capabilities
    result = jvmti_env->AddCapabilities(&capabilities);
    if (JVMTI_ERROR_NONE != result)
        return JNI_ERR;

    jvmtiEventCallbacks callbacks;
    memset(&callbacks, 0, sizeof(jvmtiEventCallbacks));
    callbacks.VMInit = vm_init_callback;

    // Set callback for VMInit
    result = jvmti_env->SetEventCallbacks(&callbacks, (jint)sizeof(callbacks));
    if (JVMTI_ERROR_NONE != result)
        return JNI_ERR;

    // Set event mode to true
    result = jvmti_env->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_INIT, NULL);
    if (JVMTI_ERROR_NONE != result)
        return JNI_ERR;

    return JNI_OK;
}