/*

 * Copyright (c) 2016, 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 <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_PTR(x) x

#else

#define JNI_ENV_ARG(x,y) x, y

#define JNI_ENV_PTR(x) (*x)

#endif

#endif

#define TranslateError(err) "JVMTI error"

#define PASSED 0

#define FAILED 2

static const char *EXPECTED_NAME = "java/util/Collections";

static const char *EXC_CNAME = "java/lang/Exception";

static jvmtiEnv *jvmti = NULL;

static jint result = PASSED;

static jboolean printdump = JNI_FALSE;

static jboolean with_early_vm_start_capability = JNI_FALSE;

static jboolean with_early_class_hook_capability = JNI_FALSE;

static jboolean found_class_in_vm_start = JNI_FALSE;

static jboolean found_class_in_primordial = JNI_FALSE;

static jboolean found_class_in_cflh_events = JNI_FALSE;

static int cflh_events_primordial_count = 0;

static int cflh_events_vm_start_count = 0;

static jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved);

JNIEXPORT

jint JNICALL Agent_OnLoad(JavaVM *jvm, char *options, void *reserved) {

    return Agent_Initialize(jvm, options, reserved);

}

JNIEXPORT

jint JNICALL Agent_OnAttach(JavaVM *jvm, char *options, void *reserved) {

    return Agent_Initialize(jvm, options, reserved);

}

JNIEXPORT

jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved) {

    return JNI_VERSION_9;

}

static

jint throw_exc(JNIEnv *env, char *msg) {

    jclass exc_class = JNI_ENV_PTR(env)->FindClass(JNI_ENV_ARG(env, EXC_CNAME));

    if (exc_class == NULL) {

        printf("throw_exc: Error in FindClass(env, %s)\n", EXC_CNAME);

        return -1;

    }

    return JNI_ENV_PTR(env)->ThrowNew(JNI_ENV_ARG(env, exc_class), msg);

}

static void JNICALL

Callback_ClassFileLoadHook(jvmtiEnv *jvmti_env, 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) {

    jvmtiPhase phase;

    jvmtiError err;

    err = (*jvmti)->GetPhase(jvmti_env, &phase);

    if (err != JVMTI_ERROR_NONE) {

        printf("ClassFileLoadHook event: GetPhase error: %s (%d)\n", TranslateError(err), err);

        result = FAILED;

        return;

    }

    if (phase == JVMTI_PHASE_PRIMORDIAL || phase == JVMTI_PHASE_START) {

        if (phase == JVMTI_PHASE_START) {

            cflh_events_vm_start_count++;

            if(strcmp(name, EXPECTED_NAME) == 0) {

                found_class_in_vm_start = JNI_TRUE;

            }

        } else {

            cflh_events_primordial_count++;

            if(strcmp(name, EXPECTED_NAME) == 0) {

                found_class_in_primordial = JNI_TRUE;

            }

        }

    }

    if(strcmp(name, EXPECTED_NAME) == 0) {

        found_class_in_cflh_events = JNI_TRUE;

    }

    if (printdump == JNI_TRUE) {

        printf(">>>    ClassFileLoadHook event: phase(%d), class name %s\n", phase, name);

    }

}

static

jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved) {

    jint res, size;

    jvmtiCapabilities caps;

    jvmtiEventCallbacks callbacks;

    jvmtiError err;

    if (options != NULL) {

        if (strstr(options, "with_early_vmstart") != NULL) {

            with_early_vm_start_capability = JNI_TRUE;

        }

        if (strstr(options, "with_early_class_hook") != NULL) {

            with_early_class_hook_capability = JNI_TRUE;

        }

        if (strstr(options, "printdump") != NULL) {

            printdump = JNI_TRUE;

        }

    }

    res = JNI_ENV_PTR(jvm)->GetEnv(JNI_ENV_ARG(jvm, (void **) &jvmti),

        JVMTI_VERSION_9);

    if (res != JNI_OK || jvmti == NULL) {

        printf("    Error: wrong result of a valid call to GetEnv!\n");

        return JNI_ERR;

    }

    printf("Enabling following capabilities: can_generate_all_class_hook_events");

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

    caps.can_generate_all_class_hook_events = 1;

    if (with_early_vm_start_capability == JNI_TRUE) {

        printf(", can_generate_early_vmstart");

        caps.can_generate_early_vmstart = 1;

    }

    if (with_early_class_hook_capability == JNI_TRUE) {

        printf(", can_generate_early_class_hook_events");

        caps.can_generate_early_class_hook_events = 1;

    }

    printf("\n");

    err = (*jvmti)->AddCapabilities(jvmti, &caps);

    if (err != JVMTI_ERROR_NONE) {

        printf("    Error in AddCapabilites: %s (%d)\n", TranslateError(err), err);

        return JNI_ERR;

    }

    size = (jint)sizeof(callbacks);

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

    callbacks.ClassFileLoadHook = Callback_ClassFileLoadHook;

    err = (*jvmti)->SetEventCallbacks(jvmti, &callbacks, size);

    if (err != JVMTI_ERROR_NONE) {

        printf("    Error in SetEventCallbacks: %s (%d)\n", TranslateError(err), err);

        return JNI_ERR;

    }

    err = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, NULL);

    if (err != JVMTI_ERROR_NONE) {

        printf("    Error in SetEventNotificationMode: %s (%d)\n", TranslateError(err), err);

        return JNI_ERR;

    }

    return JNI_OK;

}

JNIEXPORT jint JNICALL

Java_MAAClassFileLoadHook_check(JNIEnv *env, jclass cls) {

    jobject loader = NULL;

    if (jvmti == NULL) {

        throw_exc(env, "JVMTI client was not properly loaded!\n");

        return FAILED;

    }

    /*

     * Expecting that we always get ClassFileLoadHook events in the VM Start phase.

     */

    if (cflh_events_vm_start_count == 0) {

        throw_exc(env, "Didn't get ClassFileLoadHook events in start phase!\n");

        return FAILED;

    }

    if (with_early_class_hook_capability == JNI_TRUE) {

       /*

        * Expecting that we get ClassFileLoadHook events in the Primordial phase

        * when can_generate_all_class_hook_events and can_generate_early_class_hook_events

        * capabilities are enabled.

        */

        if (cflh_events_primordial_count == 0) {

            throw_exc(env, "Didn't get ClassFileLoadHook events in primordial phase!\n");

            return FAILED;

        }

    } else {

       /*

        * Expecting that we don't get ClassFileLoadHook events in the Primordial phase

        * when can_generate_early_class_hook_events capability is disabled.

        */

        if (cflh_events_primordial_count != 0) {

            throw_exc(env, "Get ClassFileLoadHook events in primordial phase!\n");

            return FAILED;

        }

    }

    if (with_early_vm_start_capability == JNI_TRUE) {

        /*

         * Expecting that "java/util/Collections" class from java.base module is present in the

         * ClassFileLoadHook events during VM Start phase when can_generate_early_vmstart

         * capability is enabled.

         */

        printf("Expecting to find '%s' class in ClassFileLoadHook events during VM early start phase.\n", EXPECTED_NAME);

        if (found_class_in_vm_start == JNI_FALSE) {

            throw_exc(env, "Unable to find expected class in ClassLoad events during VM early start phase!\n");

            return FAILED;

        }

    } else if (with_early_class_hook_capability == JNI_TRUE) {

        /*

         * Expecting that "java/util/Collections" class from java.base module is present in the

         * ClassFileLoadHook events during Primordial phase when can_generate_all_class_hook_events

         * and can_generate_early_class_hook_events capabilities are enabled and can_generate_early_vmstart

         * capability is disabled.

         */

        printf("Expecting to find '%s' class in ClassFileLoadHook events during VM primordial phase.\n", EXPECTED_NAME);

        if (found_class_in_primordial == JNI_FALSE) {

            throw_exc(env, "Unable to find expected class in ClassFileLoadHook events during primordial phase!\n");

            return FAILED;

        }

    } else {

        /*

         * Expecting that "java/util/Collections" class from java.base module is not present in the

         * ClassFileLoadHook events when can_generate_all_class_hook_events, can_generate_early_class_hook_events

         * and can_generate_early_vmstart capabilities are disabled.

         */

        printf("Expecting that '%s' class is absent in ClassLoadHook events.\n", EXPECTED_NAME);

        if (found_class_in_cflh_events == JNI_TRUE) {

            throw_exc(env, "Class is found in ClassFileLoadHook events!\n");

            return FAILED;

        }

    }

    return result;

}

#ifdef __cplusplus

}

#endif