JNI agent example

c++

JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM *jvm, char *options, void *reserved)
{
    jvmtiError error;
    jint res;
    jvmtiEnv *jvmti = NULL;
 
    /* Setup initial global agent data area
    *   Use of static/extern data should be handled carefully here.
    *   We need to make sure that we are able to cleanup after ourselves
    *     so anything allocated in this library needs to be freed in
    *     the Agent_OnUnload() function.
    */
 
    /*  We need to first get the jvmtiEnv* or JVMTI environment */
 
    res = jvm->GetEnv((void **) &jvmti, JVMTI_VERSION_1_0);
 
    if (res != JNI_OK || jvmti == NULL)
    {
        /* This means that the VM was unable to obtain this version of the
        *   JVMTI interface, this is a fatal error.
        */
        printf("ERROR: Unable to access JVMTI Version 1 (0x%x),"
            " is your J2SE a 1.5 or newer version?"
            " JNIEnv's GetEnv() returned %d\n",
            JVMTI_VERSION_1, res);
        return JNI_OK;
 
    }
 
    /* Here we save the jvmtiEnv* for Agent_OnUnload(). */
    jvmti_agent = boost::shared_ptr(new Darkfall::JVM::JVMTIAgent(jvm, jvmti));
 
 
    jvmtiCapabilities jvmti_supported_interpreter_capabilities =
    {
        0, // can_tag_objects
        1, // can_generate_field_modification_events
        1, // can_generate_field_access_events
        1, // can_get_bytecodes
        0, // can_get_synthetic_attribute
        0, // can_get_owned_monitor_info
        0, // can_get_current_contended_monitor
        0, // can_get_monitor_info
        0, // can_pop_frame
        1, // can_redefine_classes
        0, // can_signal_thread
        1, // can_get_source_file_name
        1, // can_get_line_numbers
        1, // can_get_source_debug_extension
        1, // can_access_local_variables
        0, // can_maintain_original_method_order
        1, // can_generate_single_step_events
        1, // can_generate_exception_events
        1, // can_generate_frame_pop_events
        1, // can_generate_breakpoint_events
        1, // can_suspend
        1, // can_redefine_any_class
        0, // can_get_current_thread_cpu_time
        0, // can_get_thread_cpu_time
        1, // can_generate_method_entry_events
        1, // can_generate_method_exit_events
        1, // can_generate_all_class_hook_events
        1, // can_generate_compiled_method_load_events
        0, // can_generate_monitor_events
        0, // can_generate_vm_object_alloc_events
        1, // can_generate_native_method_bind_events
        0, // can_generate_garbage_collection_events
        0  // can_generate_object_free_events
    };
 
 
    error = jvmti->AddCapabilities(&jvmti_supported_interpreter_capabilities);
    check_jvmti_error(jvmti, error, "Unable to get necessary JVMTI capabilities.");
 
 
    jvmtiEventCallbacks callbacks = {NULL};
    memset(&callbacks, 0, sizeof(callbacks));
    callbacks.ClassLoad               = reinterpret_cast(jvmti_callback_class_load);
    callbacks.ClassPrepare            = reinterpret_cast(jvmti_callback_class_prepare);
    callbacks.ClassFileLoadHook       = reinterpret_cast(jvmti_callback_class_file_load_hook);
    callbacks.FieldAccess             = reinterpret_cast(jvmti_callback_field_access);
    callbacks.FieldModification       = reinterpret_cast(jvmti_callback_field_modification);
    callbacks.MethodEntry             = reinterpret_cast(jvmti_callback_method_entry);
    callbacks.MethodExit              = reinterpret_cast(jvmti_callback_method_exit);
    callbacks.NativeMethodBind        = reinterpret_cast(jvmti_callback_native_method_bind);
    callbacks.VMDeath                 = reinterpret_cast(jvmti_callback_vm_death);
    callbacks.VMInit                  = reinterpret_cast(jvmti_callback_vm_init);
    callbacks.VMStart                 = reinterpret_cast(jvmti_callback_vm_start);
 
    //cb.DynamicCodeGenerated    = reinterpret_cast(jvmti_callback_dynamic_code_generated);
    //cb.SingleStep              = jvmti_callback_single_step;
    //cb.Breakpoint              = jvmti_callback_breakpoint;
    //cb.FramePop                = jvmti_callback_frame_pop;
    //cb.Exception               = jvmti_callback_exception;
    //cb.ExceptionCatch          = jvmti_callback_exception_catch;
    //cb.ThreadStart             = jvmti_callback_thread_start;
    //cb.ThreadEnd               = jvmti_callback_thread_end;
    //cb.CompiledMethodLoad      = jvmti_callback_compiled_method_load;
    //cb.CompiledMethodUnload    = jvmti_callback_compiled_method_unload;
    //cb.DataDumpRequest         = jvmti_callback_data_dump_request;
    //cb.MonitorContendedEnter   = jvmti_callback_monitor_contended_enter;
    //cb.MonitorContendedEntered = jvmti_callback_monitor_contended_entered;
    //cb.MonitorWait             = jvmti_callback_monitor_wait;
    //cb.MonitorWaited           = jvmti_callback_monitor_waited;
    //cb.VMObjectAlloc           = jvmti_callback_vm_object_alloc;
    //cb.ObjectFree              = jvmti_callback_object_free;
    //cb.GarbageCollectionStart  = jvmti_callback_garbage_collection_start;
    //cb.GarbageCollectionFinish = jvmti_callback_garbage_collection_finish;
 
    error = jvmti->SetEventCallbacks(&callbacks, (jint)sizeof(callbacks));
    check_jvmti_error(jvmti, error, "Cannot set jvmti callbacks");
 
    /* At first the only initial events we are interested in are VM
    *   initialization, VM death, and Class File Loads.
    *   Once the VM is initialized we will request more events.
    */
 
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_LOAD, reinterpret_cast(NULL));
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_PREPARE, reinterpret_cast(NULL));
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, reinterpret_cast(NULL));
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_FIELD_ACCESS, reinterpret_cast(NULL));
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_FIELD_MODIFICATION, reinterpret_cast(NULL));
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_METHOD_ENTRY, reinterpret_cast(NULL));
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_METHOD_EXIT, reinterpret_cast(NULL));
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_NATIVE_METHOD_BIND, reinterpret_cast(NULL));
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_DEATH, reinterpret_cast(NULL));
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_INIT, reinterpret_cast(NULL));
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_START, reinterpret_cast(NULL));
 
    //error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_DYNAMIC_CODE_GENERATED, reinterpret_cast(NULL));
    //error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_OBJECT_ALLOC, reinterpret_cast(NULL));
    //error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_SINGLE_STEP, reinterpret_cast(NULL));
    //error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_BREAKPOINT, reinterpret_cast(NULL));
 
    check_jvmti_error(jvmti, error, "Cannot set event notification");
 
 
    /* Here we create a raw monitor for our use in this agent to
    *   protect critical sections of code.
    */
    //error = jvmti->CreateRawMonitor(jvmti, "agent data", &(gdata->lock));
    //check_jvmti_error(jvmti, error, "Cannot create raw monitor");
 
 
    /* We return JNI_OK to signify success */
    return JNI_OK;
 
 
}