| /* |
| * Copyright (c) 2006, 2015, Oracle and/or its affiliates. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * - Neither the name of Oracle nor the names of its |
| * contributors may be used to endorse or promote products derived |
| * from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
| * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /* |
| * This source code is provided to illustrate the usage of a given feature |
| * or technique and has been deliberately simplified. Additional steps |
| * required for a production-quality application, such as security checks, |
| * input validation and proper error handling, might not be present in |
| * this sample code. |
| */ |
| |
| |
| #include "stdlib.h" |
| |
| #include "minst.h" |
| #include "java_crw_demo.h" |
| |
| |
| /* ------------------------------------------------------------------- */ |
| /* Some constant maximum sizes */ |
| |
| #define MAX_TOKEN_LENGTH 80 |
| #define MAX_METHOD_NAME_LENGTH 256 |
| |
| /* Some constant names that tie to Java class/method names. |
| * We assume the Java class whose static methods we will be calling |
| * looks like: |
| * |
| * public class Minst { |
| * private static int engaged; |
| * private static native void _method_entry(Object thr, int cnum, int mnum); |
| * public static void method_entry(int cnum, int mnum) |
| * { |
| * ... |
| * } |
| * } |
| * |
| */ |
| |
| #define MINST_class Minst /* Name of class we are using */ |
| #define MINST_entry method_entry /* Name of java entry method */ |
| #define MINST_engaged engaged /* Name of java static field */ |
| |
| /* C macros to create strings from tokens */ |
| #define _STRING(s) #s |
| #define STRING(s) _STRING(s) |
| |
| /* ------------------------------------------------------------------- */ |
| |
| /* Global agent data structure */ |
| |
| typedef struct { |
| /* JVMTI Environment */ |
| jvmtiEnv *jvmti; |
| jboolean vm_is_dead; |
| jboolean vm_is_started; |
| /* Data access Lock */ |
| jrawMonitorID lock; |
| /* Options */ |
| char *include; |
| char *exclude; |
| /* Class Count/ID */ |
| jint ccount; |
| } GlobalAgentData; |
| |
| static GlobalAgentData *gdata; |
| |
| /* Enter a critical section by doing a JVMTI Raw Monitor Enter */ |
| static void |
| enter_critical_section(jvmtiEnv *jvmti) |
| { |
| jvmtiError error; |
| |
| error = (*jvmti)->RawMonitorEnter(jvmti, gdata->lock); |
| check_jvmti_error(jvmti, error, "Cannot enter with raw monitor"); |
| } |
| |
| /* Exit a critical section by doing a JVMTI Raw Monitor Exit */ |
| static void |
| exit_critical_section(jvmtiEnv *jvmti) |
| { |
| jvmtiError error; |
| |
| error = (*jvmti)->RawMonitorExit(jvmti, gdata->lock); |
| check_jvmti_error(jvmti, error, "Cannot exit with raw monitor"); |
| } |
| |
| /* Callback for JVMTI_EVENT_VM_START */ |
| static void JNICALL |
| cbVMStart(jvmtiEnv *jvmti, JNIEnv *env) |
| { |
| enter_critical_section(jvmti); { |
| /* Indicate VM has started */ |
| gdata->vm_is_started = JNI_TRUE; |
| } exit_critical_section(jvmti); |
| } |
| |
| /* Callback for JVMTI_EVENT_VM_INIT */ |
| static void JNICALL |
| cbVMInit(jvmtiEnv *jvmti, JNIEnv *env, jthread thread) |
| { |
| enter_critical_section(jvmti); { |
| jclass klass; |
| jfieldID field; |
| |
| /* Register Natives for class whose methods we use */ |
| klass = (*env)->FindClass(env, STRING(MINST_class)); |
| if ( klass == NULL ) { |
| fatal_error("ERROR: JNI: Cannot find %s with FindClass\n", |
| STRING(MINST_class)); |
| } |
| |
| /* Engage calls. */ |
| field = (*env)->GetStaticFieldID(env, klass, STRING(MINST_engaged), "I"); |
| if ( field == NULL ) { |
| fatal_error("ERROR: JNI: Cannot get field from %s\n", |
| STRING(MINST_class)); |
| } |
| (*env)->SetStaticIntField(env, klass, field, 1); |
| } exit_critical_section(jvmti); |
| } |
| |
| /* Callback for JVMTI_EVENT_VM_DEATH */ |
| static void JNICALL |
| cbVMDeath(jvmtiEnv *jvmti, JNIEnv *env) |
| { |
| enter_critical_section(jvmti); { |
| jclass klass; |
| jfieldID field; |
| |
| /* The VM has died. */ |
| stdout_message("VMDeath\n"); |
| |
| /* Disengage calls in MINST_class. */ |
| klass = (*env)->FindClass(env, STRING(MINST_class)); |
| if ( klass == NULL ) { |
| fatal_error("ERROR: JNI: Cannot find %s with FindClass\n", |
| STRING(MINST_class)); |
| } |
| field = (*env)->GetStaticFieldID(env, klass, STRING(MINST_engaged), "I"); |
| if ( field == NULL ) { |
| fatal_error("ERROR: JNI: Cannot get field from %s\n", |
| STRING(MINST_class)); |
| } |
| (*env)->SetStaticIntField(env, klass, field, -1); |
| |
| /* The critical section here is important to hold back the VM death |
| * until all other callbacks have completed. |
| */ |
| |
| /* Since this critical section could be holding up other threads |
| * in other event callbacks, we need to indicate that the VM is |
| * dead so that the other callbacks can short circuit their work. |
| * We don't expect any further events after VmDeath but we do need |
| * to be careful that existing threads might be in our own agent |
| * callback code. |
| */ |
| gdata->vm_is_dead = JNI_TRUE; |
| |
| } exit_critical_section(jvmti); |
| |
| } |
| |
| /* Callback for JVMTI_EVENT_CLASS_FILE_LOAD_HOOK */ |
| static void JNICALL |
| cbClassFileLoadHook(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) |
| { |
| enter_critical_section(jvmti); { |
| /* It's possible we get here right after VmDeath event, be careful */ |
| if ( !gdata->vm_is_dead ) { |
| |
| const char *classname; |
| |
| /* Name could be NULL */ |
| if ( name == NULL ) { |
| classname = java_crw_demo_classname(class_data, class_data_len, |
| NULL); |
| if ( classname == NULL ) { |
| fatal_error("ERROR: No classname inside classfile\n"); |
| } |
| } else { |
| classname = strdup(name); |
| if ( classname == NULL ) { |
| fatal_error("ERROR: Out of malloc memory\n"); |
| } |
| } |
| |
| *new_class_data_len = 0; |
| *new_class_data = NULL; |
| |
| /* The tracker class itself? */ |
| if ( interested((char*)classname, "", gdata->include, gdata->exclude) |
| && strcmp(classname, STRING(MINST_class)) != 0 ) { |
| jint cnum; |
| int system_class; |
| unsigned char *new_image; |
| long new_length; |
| |
| /* Get unique number for every class file image loaded */ |
| cnum = gdata->ccount++; |
| |
| /* Is it a system class? If the class load is before VmStart |
| * then we will consider it a system class that should |
| * be treated carefully. (See java_crw_demo) |
| */ |
| system_class = 0; |
| if ( !gdata->vm_is_started ) { |
| system_class = 1; |
| } |
| |
| new_image = NULL; |
| new_length = 0; |
| |
| /* Call the class file reader/write demo code */ |
| java_crw_demo(cnum, |
| classname, |
| class_data, |
| class_data_len, |
| system_class, |
| STRING(MINST_class), "L" STRING(MINST_class) ";", |
| STRING(MINST_entry), "(II)V", |
| NULL, NULL, |
| NULL, NULL, |
| NULL, NULL, |
| &new_image, |
| &new_length, |
| NULL, |
| NULL); |
| |
| /* If we got back a new class image, return it back as "the" |
| * new class image. This must be JVMTI Allocate space. |
| */ |
| if ( new_length > 0 ) { |
| unsigned char *jvmti_space; |
| |
| jvmti_space = (unsigned char *)allocate(jvmti, (jint)new_length); |
| (void)memcpy((void*)jvmti_space, (void*)new_image, (int)new_length); |
| *new_class_data_len = (jint)new_length; |
| *new_class_data = jvmti_space; /* VM will deallocate */ |
| } |
| |
| /* Always free up the space we get from java_crw_demo() */ |
| if ( new_image != NULL ) { |
| (void)free((void*)new_image); /* Free malloc() space with free() */ |
| } |
| } |
| (void)free((void*)classname); |
| } |
| } exit_critical_section(jvmti); |
| } |
| |
| /* Parse the options for this minst agent */ |
| static void |
| parse_agent_options(char *options) |
| { |
| char token[MAX_TOKEN_LENGTH]; |
| char *next; |
| |
| /* Parse options and set flags in gdata */ |
| if ( options==NULL ) { |
| return; |
| } |
| |
| /* Get the first token from the options string. */ |
| next = get_token(options, ",=", token, sizeof(token)); |
| |
| /* While not at the end of the options string, process this option. */ |
| while ( next != NULL ) { |
| if ( strcmp(token,"help")==0 ) { |
| stdout_message("The minst JVMTI demo agent\n"); |
| stdout_message("\n"); |
| stdout_message(" java -agent:minst[=options] ...\n"); |
| stdout_message("\n"); |
| stdout_message("The options are comma separated:\n"); |
| stdout_message("\t help\t\t\t Print help information\n"); |
| stdout_message("\t include=item\t\t Only these classes/methods\n"); |
| stdout_message("\t exclude=item\t\t Exclude these classes/methods\n"); |
| stdout_message("\n"); |
| stdout_message("item\t Qualified class and/or method names\n"); |
| stdout_message("\t\t e.g. (*.<init>;Foobar.method;sun.*)\n"); |
| stdout_message("\n"); |
| exit(0); |
| } else if ( strcmp(token,"include")==0 ) { |
| int used; |
| int maxlen; |
| |
| maxlen = MAX_METHOD_NAME_LENGTH; |
| if ( gdata->include == NULL ) { |
| gdata->include = (char*)calloc(maxlen+1, 1); |
| used = 0; |
| } else { |
| used = (int)strlen(gdata->include); |
| gdata->include[used++] = ','; |
| gdata->include[used] = 0; |
| gdata->include = (char*) |
| realloc((void*)gdata->include, used+maxlen+1); |
| } |
| if ( gdata->include == NULL ) { |
| fatal_error("ERROR: Out of malloc memory\n"); |
| } |
| /* Add this item to the list */ |
| next = get_token(next, ",=", gdata->include+used, maxlen); |
| /* Check for token scan error */ |
| if ( next==NULL ) { |
| fatal_error("ERROR: include option error\n"); |
| } |
| } else if ( strcmp(token,"exclude")==0 ) { |
| int used; |
| int maxlen; |
| |
| maxlen = MAX_METHOD_NAME_LENGTH; |
| if ( gdata->exclude == NULL ) { |
| gdata->exclude = (char*)calloc(maxlen+1, 1); |
| used = 0; |
| } else { |
| used = (int)strlen(gdata->exclude); |
| gdata->exclude[used++] = ','; |
| gdata->exclude[used] = 0; |
| gdata->exclude = (char*) |
| realloc((void*)gdata->exclude, used+maxlen+1); |
| } |
| if ( gdata->exclude == NULL ) { |
| fatal_error("ERROR: Out of malloc memory\n"); |
| } |
| /* Add this item to the list */ |
| next = get_token(next, ",=", gdata->exclude+used, maxlen); |
| /* Check for token scan error */ |
| if ( next==NULL ) { |
| fatal_error("ERROR: exclude option error\n"); |
| } |
| } else if ( token[0]!=0 ) { |
| /* We got a non-empty token and we don't know what it is. */ |
| fatal_error("ERROR: Unknown option: %s\n", token); |
| } |
| /* Get the next token (returns NULL if there are no more) */ |
| next = get_token(next, ",=", token, sizeof(token)); |
| } |
| } |
| |
| /* Agent_OnLoad: This is called immediately after the shared library is |
| * loaded. This is the first code executed. |
| */ |
| JNIEXPORT jint JNICALL |
| DEF_Agent_OnLoad(JavaVM *vm, char *options, void *reserved) |
| { |
| static GlobalAgentData data; |
| jvmtiEnv *jvmti; |
| jvmtiError error; |
| jint res; |
| jvmtiCapabilities capabilities; |
| jvmtiEventCallbacks callbacks; |
| |
| /* 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. |
| */ |
| (void)memset((void*)&data, 0, sizeof(data)); |
| gdata = &data; |
| |
| /* First thing we need to do is get the jvmtiEnv* or JVMTI environment */ |
| res = (*vm)->GetEnv(vm, (void **)&jvmti, JVMTI_VERSION_1); |
| if (res != JNI_OK) { |
| /* This means that the VM was unable to obtain this version of the |
| * JVMTI interface, this is a fatal error. |
| */ |
| fatal_error("ERROR: Unable to access JVMTI Version 1 (0x%x)," |
| " is your JDK a 5.0 or newer version?" |
| " JNIEnv's GetEnv() returned %d\n", |
| JVMTI_VERSION_1, res); |
| } |
| |
| /* Here we save the jvmtiEnv* for Agent_OnUnload(). */ |
| gdata->jvmti = jvmti; |
| |
| /* Parse any options supplied on java command line */ |
| parse_agent_options(options); |
| |
| /* Immediately after getting the jvmtiEnv* we need to ask for the |
| * capabilities this agent will need. In this case we need to make |
| * sure that we can get all class load hooks. |
| */ |
| (void)memset(&capabilities,0, sizeof(capabilities)); |
| capabilities.can_generate_all_class_hook_events = 1; |
| error = (*jvmti)->AddCapabilities(jvmti, &capabilities); |
| check_jvmti_error(jvmti, error, "Unable to get necessary JVMTI capabilities."); |
| |
| /* Next we need to provide the pointers to the callback functions to |
| * to this jvmtiEnv* |
| */ |
| (void)memset(&callbacks,0, sizeof(callbacks)); |
| /* JVMTI_EVENT_VM_START */ |
| callbacks.VMStart = &cbVMStart; |
| /* JVMTI_EVENT_VM_INIT */ |
| callbacks.VMInit = &cbVMInit; |
| /* JVMTI_EVENT_VM_DEATH */ |
| callbacks.VMDeath = &cbVMDeath; |
| /* JVMTI_EVENT_CLASS_FILE_LOAD_HOOK */ |
| callbacks.ClassFileLoadHook = &cbClassFileLoadHook; |
| error = (*jvmti)->SetEventCallbacks(jvmti, &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, JVMTI_ENABLE, |
| JVMTI_EVENT_VM_START, (jthread)NULL); |
| check_jvmti_error(jvmti, error, "Cannot set event notification"); |
| error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, |
| JVMTI_EVENT_VM_INIT, (jthread)NULL); |
| check_jvmti_error(jvmti, error, "Cannot set event notification"); |
| error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, |
| JVMTI_EVENT_VM_DEATH, (jthread)NULL); |
| check_jvmti_error(jvmti, error, "Cannot set event notification"); |
| error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, |
| JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, (jthread)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"); |
| |
| /* Add demo jar file to boot classpath */ |
| add_demo_jar_to_bootclasspath(jvmti, "minst"); |
| |
| /* We return JNI_OK to signify success */ |
| return JNI_OK; |
| } |
| |
| /* Agent_OnUnload: This is called immediately before the shared library is |
| * unloaded. This is the last code executed. |
| */ |
| JNIEXPORT void JNICALL |
| DEF_Agent_OnUnload(JavaVM *vm) |
| { |
| /* Make sure all malloc/calloc/strdup space is freed */ |
| if ( gdata->include != NULL ) { |
| (void)free((void*)gdata->include); |
| gdata->include = NULL; |
| } |
| if ( gdata->exclude != NULL ) { |
| (void)free((void*)gdata->exclude); |
| gdata->exclude = NULL; |
| } |
| } |
