test/hotspot/jtreg/serviceability/jvmti/GetClassMethods/libOverpassMethods.c

/*
 * Copyright (c) 2020, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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 <stdio.h>
#include <string.h>
#include "jvmti.h"

#ifdef __cplusplus
extern "C" {
#endif

#ifndef JNI_ENV_ARG

#ifdef __cplusplus
#define JNI_ENV_ARG(x, y) y
#define JNI_ENV_ARG2(x, y, z) y, z
#define JNI_ENV_ARG3(x, y, z, v) y, z, v
#define JNI_ENV_PTR(x) x
#else
#define JNI_ENV_ARG(x,y) x, y
#define JNI_ENV_ARG2(x,y,z) x, y, z
#define JNI_ENV_ARG3(x,y,z,v) x, y, z, v
#define JNI_ENV_PTR(x) (*x)
#endif

#endif

#define ACC_STATIC 0x0008

static jvmtiEnv *jvmti = NULL;

JNIEXPORT
jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved) {
  return JNI_VERSION_9;
}

JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM *vm, char *options, void *reserved) {
  JNI_ENV_PTR(vm)->GetEnv(JNI_ENV_ARG2(vm, (void **)&jvmti, JVMTI_VERSION_11));

  if (options != NULL && strcmp(options, "maintain_original_method_order") == 0) {
    printf("Enabled capability: maintain_original_method_order\n");
    jvmtiCapabilities caps;
    memset(&caps, 0, sizeof(jvmtiCapabilities));

    caps.can_maintain_original_method_order = 1;

    jvmtiError err = JNI_ENV_PTR(jvmti)->AddCapabilities(JNI_ENV_ARG(jvmti, &caps));
    if (err != JVMTI_ERROR_NONE) {
      printf("Agent_OnLoad: AddCapabilities failed with error: %d\n", err);
      return JNI_ERR;
    }
  }
  return JNI_OK;
}

JNIEXPORT jobjectArray JNICALL Java_OverpassMethods_getJVMTIDeclaredMethods(JNIEnv *env, jclass static_klass, jclass klass) {
  jint method_count = 0;
  jmethodID* methods = NULL;
  jvmtiError err = JNI_ENV_PTR(jvmti)->GetClassMethods(JNI_ENV_ARG3(jvmti, klass, &method_count, &methods));
  if (err != JVMTI_ERROR_NONE) {
    printf("GetClassMethods failed with error: %d\n", err);
    return NULL;
  }

  jclass method_cls = JNI_ENV_PTR(env)->FindClass(JNI_ENV_ARG(env, "java/lang/reflect/Method"));
  if (method_cls == NULL) {
    printf("FindClass (Method) failed\n");
    return NULL;
  }
  jobjectArray array = JNI_ENV_PTR(env)->NewObjectArray(JNI_ENV_ARG3(env, method_count, method_cls, NULL));
  if (array == NULL) {
    printf("NewObjectArray failed\n");
    return NULL;
  }

  int i;
  for (i = 0; i < method_count; i++) {
    jint modifiers = 0;
    err = JNI_ENV_PTR(jvmti)->GetMethodModifiers(JNI_ENV_ARG2(jvmti, methods[i], &modifiers));
    if (err != JVMTI_ERROR_NONE) {
      printf("GetMethodModifiers failed with error: %d\n", err);
      return NULL;
    }

    jobject m = JNI_ENV_PTR(env)->ToReflectedMethod(JNI_ENV_ARG3(env, klass, methods[i], (modifiers & ACC_STATIC) == ACC_STATIC));
    if (array == NULL) {
      printf("ToReflectedMethod failed\n");
      return NULL;
    }
    JNI_ENV_PTR(env)->SetObjectArrayElement(JNI_ENV_ARG3(env, array, i, m));

    JNI_ENV_PTR(env)->DeleteLocalRef(JNI_ENV_ARG(env, m));
  }
  JNI_ENV_PTR(jvmti)->Deallocate(JNI_ENV_ARG(jvmti, (unsigned char *)methods));

  return array;
}
#ifdef __cplusplus
}
#endif