/*

 * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "jvm.h"

#include "jfr/instrumentation/jfrJvmtiAgent.hpp"

#include "jfr/jni/jfrJavaSupport.hpp"

#include "jfr/jni/jfrUpcalls.hpp"

#include "jfr/recorder/checkpoint/types/traceid/jfrTraceId.inline.hpp"

#include "jfr/recorder/service/jfrOptionSet.hpp"

#include "jfr/support/jfrEventClass.hpp"

#include "logging/log.hpp"

#include "memory/resourceArea.hpp"

#include "prims/jvmtiExport.hpp"

#include "runtime/interfaceSupport.inline.hpp"

#include "runtime/thread.inline.hpp"

#include "utilities/exceptions.hpp"

static const size_t ERROR_MSG_BUFFER_SIZE = 256;

static JfrJvmtiAgent* agent = NULL;

static jvmtiEnv* jfr_jvmti_env = NULL;

static void check_jvmti_error(jvmtiEnv* jvmti, jvmtiError errnum, const char* str) {

  if (errnum != JVMTI_ERROR_NONE) {

    char* errnum_str = NULL;

    jvmti->GetErrorName(errnum, &errnum_str);

    log_error(jfr, system)("ERROR: JfrJvmtiAgent: " INT32_FORMAT " (%s): %s\n",

                           errnum,

                           NULL == errnum_str ? "Unknown" : errnum_str,

                           NULL == str ? "" : str);

  }

}

static jvmtiError set_event_notification_mode(jvmtiEventMode mode,

                                              jvmtiEvent event,

                                              jthread event_thread,

                                              ...) {

  if (jfr_jvmti_env == NULL) {

    return JVMTI_ERROR_NONE;

  }

  const jvmtiError jvmti_ret_code = jfr_jvmti_env->SetEventNotificationMode(mode, event, event_thread);

  check_jvmti_error(jfr_jvmti_env, jvmti_ret_code, "SetEventNotificationMode");

  return jvmti_ret_code;

}

static jvmtiError update_class_file_load_hook_event(jvmtiEventMode mode) {

  return set_event_notification_mode(mode, JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, NULL);

}

static JavaThread* current_java_thread() {

  Thread* this_thread = Thread::current();

  assert(this_thread != NULL && this_thread->is_Java_thread(), "invariant");

  return static_cast<JavaThread*>(this_thread);

}

// jvmti event callbacks require C linkage

extern "C" void JNICALL jfr_on_class_file_load_hook(jvmtiEnv *jvmti_env,

                                                    JNIEnv* jni_env,

                                                    jclass class_being_redefined,

                                                    jobject loader,

                                                    const char* name,

                                                    jobject protection_domain,

                                                    jint class_data_len,

                                                    const unsigned char* class_data,

                                                    jint* new_class_data_len,

                                                    unsigned char** new_class_data) {

  if (class_being_redefined == NULL) {

    return;

  }

  JavaThread* jt = JavaThread::thread_from_jni_environment(jni_env);

  DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_native(jt));;

  ThreadInVMfromNative tvmfn(jt);

  JfrUpcalls::on_retransform(JfrTraceId::get(class_being_redefined),

                             class_being_redefined,

                             class_data_len,

                             class_data,

                             new_class_data_len,

                             new_class_data,

                             jt);

}

// caller needs ResourceMark

static jclass* create_classes_array(jint classes_count, TRAPS) {

  assert(classes_count > 0, "invariant");

  DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_native(THREAD));

  ThreadInVMfromNative tvmfn((JavaThread*)THREAD);

  jclass* const classes = NEW_RESOURCE_ARRAY_IN_THREAD_RETURN_NULL(THREAD, jclass, classes_count);

  if (NULL == classes) {

    char error_buffer[ERROR_MSG_BUFFER_SIZE];

    jio_snprintf(error_buffer, ERROR_MSG_BUFFER_SIZE,

      "Thread local allocation (native) of " SIZE_FORMAT " bytes failed "

      "in retransform classes", sizeof(jclass) * classes_count);

    log_error(jfr, system)("%s", error_buffer);

    JfrJavaSupport::throw_out_of_memory_error(error_buffer, CHECK_NULL);

  }

  return classes;

}

static void log_and_throw(TRAPS) {

  if (!HAS_PENDING_EXCEPTION) {

    DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_native(THREAD));

    ThreadInVMfromNative tvmfn((JavaThread*)THREAD);

    log_error(jfr, system)("JfrJvmtiAgent::retransformClasses failed");

    JfrJavaSupport::throw_class_format_error("JfrJvmtiAgent::retransformClasses failed", THREAD);

  }

}

static void check_exception_and_log(JNIEnv* env, TRAPS) {

  assert(env != NULL, "invariant");

  if (env->ExceptionOccurred()) {

    // array index out of bound

    DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_native(THREAD));

    ThreadInVMfromNative tvmfn((JavaThread*)THREAD);

    log_error(jfr, system)("GetObjectArrayElement threw an exception");

    return;

  }

}

void JfrJvmtiAgent::retransform_classes(JNIEnv* env, jobjectArray classes_array, TRAPS) {

  assert(env != NULL, "invariant");

  DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_native(THREAD));

  if (classes_array == NULL) {

    return;

  }

  const jint classes_count = env->GetArrayLength(classes_array);

  if (classes_count <= 0) {

    return;

  }

  ResourceMark rm(THREAD);

  jclass* const classes = create_classes_array(classes_count, CHECK);

  assert(classes != NULL, "invariant");

  for (jint i = 0; i < classes_count; i++) {

    jclass clz = (jclass)env->GetObjectArrayElement(classes_array, i);

    check_exception_and_log(env, THREAD);

    // inspecting the oop/klass requires a thread transition

    {

      ThreadInVMfromNative transition((JavaThread*)THREAD);

      if (JdkJfrEvent::is_a(clz)) {

        // should have been tagged already

        assert(JdkJfrEvent::is_subklass(clz), "invariant");

      } else {

        // outside the event hierarchy

        JdkJfrEvent::tag_as_host(clz);

      }

    }

    classes[i] = clz;

  }

  if (jfr_jvmti_env->RetransformClasses(classes_count, classes) != JVMTI_ERROR_NONE) {

    log_and_throw(THREAD);

  }

}

static jvmtiError register_callbacks(JavaThread* jt) {

  assert(jfr_jvmti_env != NULL, "invariant");

  DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_native(jt));

  jvmtiEventCallbacks callbacks;

  /* Set callbacks */

  memset(&callbacks, 0, sizeof(callbacks));

  callbacks.ClassFileLoadHook = jfr_on_class_file_load_hook;

  const jvmtiError jvmti_ret_code = jfr_jvmti_env->SetEventCallbacks(&callbacks, sizeof(callbacks));

  check_jvmti_error(jfr_jvmti_env, jvmti_ret_code, "SetEventCallbacks");

  return jvmti_ret_code;

}

static jvmtiError register_capabilities(JavaThread* jt) {

  assert(jfr_jvmti_env != NULL, "invariant");

  DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_native(jt));

  jvmtiCapabilities capabilities;

  /* Add JVMTI capabilities */

  (void)memset(&capabilities, 0, sizeof(capabilities));

  capabilities.can_retransform_classes = 1;

  capabilities.can_retransform_any_class = 1;

  const jvmtiError jvmti_ret_code = jfr_jvmti_env->AddCapabilities(&capabilities);

  check_jvmti_error(jfr_jvmti_env, jvmti_ret_code, "Add Capabilities");

  return jvmti_ret_code;

}

static jint create_jvmti_env(JavaThread* jt) {

  assert(jfr_jvmti_env == NULL, "invariant");

  DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_native(jt));

  extern struct JavaVM_ main_vm;

  JavaVM* vm = &main_vm;

  return vm->GetEnv((void **)&jfr_jvmti_env, JVMTI_VERSION);

}

static jvmtiError unregister_callbacks(JavaThread* jt) {

  if (jfr_jvmti_env == NULL) {

    return JVMTI_ERROR_NONE;

  }

  jvmtiEventCallbacks callbacks;

  /* Set empty callbacks */

  memset(&callbacks, 0, sizeof(callbacks));

  const jvmtiError jvmti_ret_code = jfr_jvmti_env->SetEventCallbacks(&callbacks, sizeof(callbacks));

  check_jvmti_error(jfr_jvmti_env, jvmti_ret_code, "SetEventCallbacks");

  return jvmti_ret_code;

}

JfrJvmtiAgent::JfrJvmtiAgent() {}

JfrJvmtiAgent::~JfrJvmtiAgent() {

  JavaThread* jt = current_java_thread();

  DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(jt));

  ThreadToNativeFromVM transition(jt);

  update_class_file_load_hook_event(JVMTI_DISABLE);

  unregister_callbacks(jt);

  if (jfr_jvmti_env != NULL) {

    jfr_jvmti_env->DisposeEnvironment();

    jfr_jvmti_env = NULL;

  }

  agent = NULL;

}

static bool initialize() {

  JavaThread* const jt = current_java_thread();

  assert(jt != NULL, "invariant");

  assert(jt->thread_state() == _thread_in_vm, "invariant");

  DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(jt));

  ThreadToNativeFromVM transition(jt);

  if (create_jvmti_env(jt) != JNI_OK) {

    assert(jfr_jvmti_env == NULL, "invariant");

    return false;

  }

  assert(jfr_jvmti_env != NULL, "invariant");

  if (register_capabilities(jt) != JVMTI_ERROR_NONE) {

    return false;

  }

  if (register_callbacks(jt) != JVMTI_ERROR_NONE) {

    return false;

  }

  if (update_class_file_load_hook_event(JVMTI_ENABLE) != JVMTI_ERROR_NONE) {

    return false;

  }

  return true;

}

bool JfrJvmtiAgent::create() {

  assert(jfr_jvmti_env == NULL, "invariant");

  agent = new JfrJvmtiAgent();

  if (agent == NULL) {

    return false;

  }

  if (!initialize()) {

    delete agent;

    agent = NULL;

    return false;

  }

  return true;

}

void JfrJvmtiAgent::destroy() {

  if (agent != NULL) {

    delete agent;

    agent = NULL;

  }

}