Hi Charlie,
I do not see any obvious errors in your code except what Mikael mentioned below.
Could you, please, check if asserts are really enabled in your runs on Windows?
Also, I agree with Mikael that it would be better to get rid of these asserts or
refactor the code to use asserts only to check results like below:
jvmtiError err = jvmti->AddCapabilities(&capabilities);
assert(res == JVMTI_ERROR_NONE);
Also, what are your command-line options?
Thanks,
Serguei
On 12/1/21, 1:17 AM, "hotspot-dev on behalf of Daniel D. Daugherty"
<hotspot-dev-r...@openjdk.java.net on behalf of daniel.daughe...@oracle.com>
wrote:
Redirecting to the serviceability-dev@... alias since JVM/TI is maintained
by the Serviceability team...
Dan
On 1/10/21 6:09 PM, Mikael Vidstedt wrote:
> Just a control question: Are you *sure* asserts are actually enabled?
Having actual application logic in an assert is normally a bad idea because
if/when you compile the release/production version with asserts disabled the
application behavior will change.
>
> Cheers,
> Mikael
>
>> On Jan 10, 2021, at 8:33 AM, Charlie <cvdcamill...@gmail.com> wrote:
>>
>> Hi,
>>
>> I have a working jvmti agent on Linux (Java(TM) SE Runtime Environment
(build 1.8.0_271-b09)) that hooks the class load event.
>>
>> This same agent compiled for windows claims to work (all asserts pass),
but my hook never gets called, is anyone able to tell me why?
>>
>> I register my callback like so:
>>
>> jint res = vm->GetEnv(reinterpret_cast<void **>(&jvmti),
JVMTI_VERSION_1);
>> if (res != JNI_OK || jvmti==nullptr) {
>> fprintf(stderr,"Unable to get JVMTI!");
>> }
>> assert(res == JVMTI_ERROR_NONE);
>>
>> jvmtiCapabilities capabilities = {0};
>> capabilities.can_retransform_classes=1;
>> capabilities.can_generate_all_class_hook_events = 1;
>>
>> assert(jvmti->AddCapabilities(&capabilities) == JVMTI_ERROR_NONE);
>>
>> jvmtiEventCallbacks callbacks;
>> memset(&callbacks,0,sizeof(callbacks));
>> callbacks.ClassFileLoadHook = &class_file_load_hook_handler;
>> assert(jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks)) ==
JVMTI_ERROR_NONE);
>> assert(jvmti->SetEventNotificationMode(JVMTI_ENABLE,
JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, nullptr) == JVMTI_ERROR_NONE);
>>
>> The callback itself is as follows:
>>
>> static void JNICALL class_file_load_hook_handler(
>> jvmtiEnv* jvmti,
>> JNIEnv* 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 (name == nullptr) {
>> return;
>> }
>>
>> printf("loaded %s\n",name);
>>
>> }
>>
>> (to clarify, all JNI functions in the lib work fine)
>>
>> The Windows machine's java version string is this:
>>
>> java version "1.8.0_271"
>> Java(TM) SE Runtime Environment (build 1.8.0_271-b09)
>> Java HotSpot(TM) 64-Bit Server VM (build 25.271-b09, mixed mode)
>>
