diff -r 4ebc2e2fb97c -r 71c04702a3d5 test/hotspot/jtreg/testlibrary/jvmti/libSimpleClassFileLoadHook.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/test/hotspot/jtreg/testlibrary/jvmti/libSimpleClassFileLoadHook.c Tue Sep 12 19:03:39 2017 +0200 @@ -0,0 +1,166 @@ +/* + * 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. + */ + +/* + * A simple way to test JVMTI ClassFileLoadHook. See ../testlibrary_tests/SimpleClassFileLoadHookTest.java + * for an example. + */ +#include +#include +#include +#include + +#include +#include + +static char* CLASS_NAME = NULL; +static char* FROM = NULL; +static char* TO = NULL; +static jvmtiEnv *jvmti = NULL; +static jvmtiEventCallbacks callbacks; + +/** + * For all classes whose name equals to CLASS_NAME, we replace all occurrence of FROM to TO + * in the classfile data. CLASS_NAME must be a binary class name. + * + * FROM is usually chosen as part of a UTF8 string in the class file. For example, if the + * original class file has + * String getXXX() { return "theXXX";} + * You can set FROM=XXX, TO=YYY to rewrite the class to be + * String getYYY() { return "theYYY";} + * + * Please note that the replacement is NOT limited just the UTF8 strings, but rather applies + * to all the bytes in the classfile. So if you pick a very short FROM string like X, + * it may override any POP2 bytecodes, which have the value 88 (ascii 'X'). + * + * A good FROM string to use is 'cellphone', where the first 4 bytes represent the bytecode + * sequence DADD/LSUB/IDIV/IDIV, which does not appear in valid bytecode streams. + */ +void JNICALL +ClassFileLoadHook(jvmtiEnv *jvmti_env, JNIEnv *env, jclass class_beeing_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 != NULL && (strcmp(name, CLASS_NAME) == 0)) { + size_t n = strlen(FROM); + unsigned char* new_data; + + if ((*jvmti)->Allocate(jvmti, class_data_len, &new_data) == JNI_OK) { + const unsigned char* s = class_data; + unsigned char* d = new_data; + unsigned char* end = d + class_data_len; + int count = 0; + + fprintf(stderr, "found class to be hooked: %s - rewriting ...\n", name); + + while (d + n < end) { + if (memcmp(s, FROM, n) == 0) { + memcpy(d, TO, n); + s += n; + d += n; + count++; + } else { + *d++ = *s++; + } + } + while (d < end) { + *d++ = *s++; + } + + *new_class_data_len = class_data_len; + *new_class_data = new_data; + + fprintf(stderr, "Rewriting done. Replaced %d occurrence(s)\n", count); + } + } +} + +static jint init_options(char *options) { + char* class_name; + char* from; + char* to; + + fprintf(stderr, "Agent library loaded with options = %s\n", options); + if ((class_name = options) != NULL && + (from = strchr(class_name, ',')) != NULL && (from[1] != 0)) { + *from = 0; + from++; + if ((to = strchr(from, ',')) != NULL && (to[1] != 0)) { + *to = 0; + to++; + if (strchr(to, ',') == NULL && + strlen(to) == strlen(from) && + strlen(class_name) > 0 && + strlen(to) > 0) { + CLASS_NAME = strdup(class_name); + FROM = strdup(from); + TO = strdup(to); + fprintf(stderr, "CLASS_NAME = %s, FROM = %s, TO = %s\n", + CLASS_NAME, FROM, TO); + return JNI_OK; + } + } + } + fprintf(stderr, + "Incorrect options. You need to start the JVM with -agentlib:ClassFileLoadHook=,,\n" + "where is the class you want to hook, is the string in the classfile to be replaced\n" + "with . and must have the same length. Example:\n" + " @run main/native -agentlib:ClassFileLoadHook=Foo,XXX,YYY ClassFileLoadHookTest\n"); + return JNI_ERR; +} + +static jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved) { + int rc; + + if ((rc = (*jvm)->GetEnv(jvm, (void **)&jvmti, JVMTI_VERSION_1_1)) != JNI_OK) { + fprintf(stderr, "Unable to create jvmtiEnv, GetEnv failed, error = %d\n", rc); + return JNI_ERR; + } + if ((rc = init_options(options)) != JNI_OK) { + return JNI_ERR; + } + + (void) memset(&callbacks, 0, sizeof(callbacks)); + callbacks.ClassFileLoadHook = &ClassFileLoadHook; + if ((rc = (*jvmti)->SetEventCallbacks(jvmti, &callbacks, sizeof(callbacks))) != JNI_OK) { + fprintf(stderr, "SetEventCallbacks failed, error = %d\n", rc); + return JNI_ERR; + } + + if ((rc = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, + JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, NULL)) != JNI_OK) { + fprintf(stderr, "SetEventNotificationMode failed, error = %d\n", rc); + return JNI_ERR; + } + + return JNI_OK; +} + +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); +}