/*

 * Copyright (c) 1998, 2007, 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.

 */

/*

 * eventHandler

 *

 * This module handles events as they come in directly from JVMTI

 * and also maps them to JDI events.  JDI events are those requested

 * at the JDI or JDWP level and seen on those levels.  Mapping is

 * one-to-many, a JVMTI event may map to several JDI events, or

 * to none.  Part of that mapping process is filteration, which

 * eventFilter sub-module handles.  A JDI EventRequest corresponds

 * to a HandlerNode and a JDI filter to the hidden HandlerNode data

 * used by eventFilter.  For example, if at the JDI level the user

 * executed:

 *

 *   EventRequestManager erm = vm.eventRequestManager();

 *   BreakpointRequest bp = erm.createBreakpointRequest();

 *   bp.enable();

 *   ClassPrepareRequest req = erm.createClassPrepareRequest();

 *   req.enable();

 *   req = erm.createClassPrepareRequest();

 *   req.addClassFilter("Foo*");

 *   req.enable();

 *

 * Three handlers would be created, the first with a LocationOnly

 * filter and the last with a ClassMatch  filter.

 * When a JVMTI class prepare event for "Foobar"

 * comes in, the second handler will create one JDI event, the

 * third handler will compare the class signature, and since

 * it matchs create a second event.  There may also be internal

 * events as there are in this case, one created by the front-end

 * and one by the back-end.

 *

 * Each event kind has a handler chain, which is a doublely linked

 * list of handlers for that kind of event.

 */

#include "util.h"

#include "eventHandler.h"

#include "eventHandlerRestricted.h"

#include "eventFilter.h"

#include "eventFilterRestricted.h"

#include "standardHandlers.h"

#include "threadControl.h"

#include "eventHelper.h"

#include "classTrack.h"

#include "commonRef.h"

#include "debugLoop.h"

static HandlerID requestIdCounter;

static jbyte currentSessionID;

/* Counter of active callbacks and flag for vm_death */

static int      active_callbacks   = 0;

static jboolean vm_death_callback_active = JNI_FALSE;

static jrawMonitorID callbackLock;

static jrawMonitorID callbackBlock;

/* Macros to surround callback code (non-VM_DEATH callbacks).

 *   Note that this just keeps a count of the non-VM_DEATH callbacks that

 *   are currently active, it does not prevent these callbacks from

 *   operating in parallel. It's the VM_DEATH callback that will wait

 *   for all these callbacks to finish up, so that it can report the

 *   VM_DEATH in a clean state.

 *   If the VM_DEATH callback is active in the BEGIN macro then this

 *   callback just blocks until released by the VM_DEATH callback.

 *   If the VM_DEATH callback is active in the END macro, then this

 *   callback will notify the VM_DEATH callback if it's the last one,

 *   and then block until released by the VM_DEATH callback.

 *   Why block? These threads are often the threads of the Java program,

 *   not blocking might mean that a return would continue execution of

 *   some java thread in the middle of VM_DEATH, this seems troubled.

 *

 *   WARNING: No not 'return' or 'goto' out of the BEGIN_CALLBACK/END_CALLBACK

 *            block, this will mess up the count.

 */

#define BEGIN_CALLBACK()                                                \

{ /* BEGIN OF CALLBACK */                                               \

    jboolean bypass = JNI_TRUE;                                         \

    debugMonitorEnter(callbackLock); {                                  \

        if (vm_death_callback_active) {                                 \

            /* allow VM_DEATH callback to finish */                     \

            debugMonitorExit(callbackLock);                             \

            /* Now block because VM is about to die */                  \

            debugMonitorEnter(callbackBlock);                           \

            debugMonitorExit(callbackBlock);                            \

        } else {                                                        \

            active_callbacks++;                                         \

            bypass = JNI_FALSE;                                         \

            debugMonitorExit(callbackLock);                             \

        }                                                               \

    }                                                                   \

    if ( !bypass ) {                                                    \

        /* BODY OF CALLBACK CODE */

#define END_CALLBACK() /* Part of bypass if body */                     \

        debugMonitorEnter(callbackLock); {                              \

            active_callbacks--;                                         \

            if (active_callbacks < 0) {                                 \

                EXIT_ERROR(0, "Problems tracking active callbacks");    \

            }                                                           \

            if (vm_death_callback_active) {                             \

                if (active_callbacks == 0) {                            \

                    debugMonitorNotifyAll(callbackLock);                \

                }                                                       \

                /* allow VM_DEATH callback to finish */                 \

                debugMonitorExit(callbackLock);                         \

                /* Now block because VM is about to die */              \

                debugMonitorEnter(callbackBlock);                       \

                debugMonitorExit(callbackBlock);                        \

            } else {                                                    \

                debugMonitorExit(callbackLock);                         \

            }                                                           \

        }                                                               \

    }                                                                   \

} /* END OF CALLBACK */

/*

 * We are starting with a very simple locking scheme

 * for event handling.  All readers and writers of data in

 * the handlers[] chain must own this lock for the duration

 * of its use. If contention becomes a problem, we can:

 *

 * 1) create a lock per event type.

 * 2) move to a readers/writers approach where multiple threads

 * can access the chains simultaneously while reading (the

 * normal activity of an event callback).

 */

static jrawMonitorID handlerLock;

typedef struct HandlerChain_ {

    HandlerNode *first;

    /* add lock here */

} HandlerChain;

/*

 * This array maps event kinds to handler chains.

 * Protected by handlerLock.

 */

static HandlerChain __handlers[EI_max-EI_min+1];

/* Given a HandlerNode, these access our private data.

 */

#define PRIVATE_DATA(node) \

       (&(((EventHandlerRestricted_HandlerNode*)(void*)(node))->private_ehpd))

#define NEXT(node) (PRIVATE_DATA(node)->private_next)

#define PREV(node) (PRIVATE_DATA(node)->private_prev)

#define CHAIN(node) (PRIVATE_DATA(node)->private_chain)

#define HANDLER_FUNCTION(node) (PRIVATE_DATA(node)->private_handlerFunction)

static jclass getObjectClass(jobject object);

static jvmtiError freeHandler(HandlerNode *node);

static jvmtiError freeHandlerChain(HandlerChain *chain);

static HandlerChain *

getHandlerChain(EventIndex i)

{

    if ( i < EI_min || i > EI_max ) {

        EXIT_ERROR(AGENT_ERROR_INVALID_EVENT_TYPE,"bad index for handler");

    }

    return &(__handlers[i-EI_min]);

}

static void

insert(HandlerChain *chain, HandlerNode *node)

{

    HandlerNode *oldHead = chain->first;

    NEXT(node) = oldHead;

    PREV(node) = NULL;

    CHAIN(node) = chain;

    if (oldHead != NULL) {

        PREV(oldHead) = node;

    }

    chain->first = node;

}

static HandlerNode *

findInChain(HandlerChain *chain, HandlerID handlerID)

{

    HandlerNode *node = chain->first;

    while (node != NULL) {

        if (node->handlerID == handlerID) {

            return node;

        }

        node = NEXT(node);

    }

    return NULL;

}

static HandlerNode *

find(EventIndex ei, HandlerID handlerID)

{

    return findInChain(getHandlerChain(ei), handlerID);

}

/**

 * Deinsert.  Safe for non-inserted nodes.

 */

static void

deinsert(HandlerNode *node)

{

    HandlerChain *chain = CHAIN(node);

    if (chain == NULL) {

        return;

    }

    if (chain->first == node) {

        chain->first = NEXT(node);

    }

    if (NEXT(node) != NULL) {

        PREV(NEXT(node)) = PREV(node);

    }

    if (PREV(node) != NULL) {

        NEXT(PREV(node)) = NEXT(node);

    }

    CHAIN(node) = NULL;

}

jboolean

eventHandlerRestricted_iterator(EventIndex ei,

                              IteratorFunction func, void *arg)

{

    HandlerChain *chain;

    HandlerNode *node;

    JNIEnv *env;

    chain = getHandlerChain(ei);

    node = chain->first;

    env = getEnv();

    if ( func == NULL ) {

        EXIT_ERROR(AGENT_ERROR_INTERNAL,"iterator function NULL");

    }

    while (node != NULL) {

        if (((func)(env, node, arg))) {

            return JNI_TRUE;

        }

        node = NEXT(node);

    }

    return JNI_FALSE;

}

/* BREAKPOINT, METHOD_ENTRY and SINGLE_STEP events are covered by

 * the co-location of events policy. Of these three co-located

 * events, METHOD_ENTRY is  always reported first and BREAKPOINT

 * is always reported last. Here are the possible combinations and

 * their order:

 *

 * (p1) METHOD_ENTRY, BREAKPOINT (existing)

 * (p2) METHOD_ENTRY, BREAKPOINT (new)

 * (p1) METHOD_ENTRY, SINGLE_STEP

 * (p1) METHOD_ENTRY, SINGLE_STEP, BREAKPOINT (existing)

 * (p1/p2) METHOD_ENTRY, SINGLE_STEP, BREAKPOINT (new)

 * (p1) SINGLE_STEP, BREAKPOINT (existing)

 * (p2) SINGLE_STEP, BREAKPOINT (new)

 *

 * BREAKPOINT (existing) indicates a BREAKPOINT that is set before

 * the other co-located event is posted. BREAKPOINT (new) indicates

 * a BREAKPOINT that is set after the other co-located event is

 * posted and before the thread has resumed execution.

 *

 * Co-location of events policy used to be implemented via

 * temporary BREAKPOINTs along with deferring the reporting of

 * non-BREAKPOINT co-located events, but the temporary BREAKPOINTs

 * caused performance problems on VMs where setting or clearing

 * BREAKPOINTs is expensive, e.g., HotSpot.

 *

 * The policy is now implemented in two phases. Phase 1: when a

 * METHOD_ENTRY or SINGLE_STEP event is received, if there is an

 * existing co-located BREAKPOINT, then the current event is

 * deferred. When the BREAKPOINT event is processed, the event

 * bag will contain the deferred METHOD_ENTRY and/or SINGLE_STEP

 * events along with the BREAKPOINT event. For a METHOD_ENTRY

 * event where there is not an existing co-located BREAKPOINT,

 * if SINGLE_STEP events are also enabled for the thread, then

 * the METHOD_ENTRY event is deferred. When the SINGLE_STEP event

 * is processed, the event bag will also contain the deferred

 * METHOD_ENTRY event. This covers each of the combinations

 * marked with 'p1' above.

 *

 * Phase 2: if there is no existing co-located BREAKPOINT, then the

 * location information for the METHOD_ENTRY or SINGLE_STEP event

 * is recorded in the ThreadNode. If the next event for the thread

 * is a co-located BREAKPOINT, then the first BREAKPOINT event will

 * be skipped since it cannot be delivered in the same event set.

 * This covers each of the combinations marked with 'p2' above.

 *

 * For the combination marked p1/p2, part of the case is handled

 * during phase 1 and the rest is handled during phase 2.

 *

 * The recording of information in the ThreadNode is handled in

 * this routine. The special handling of the next event for the

 * thread is handled in skipEventReport().

 */

static jboolean

deferEventReport(JNIEnv *env, jthread thread,

            EventIndex ei, jclass clazz, jmethodID method, jlocation location)

{

    jboolean deferring = JNI_FALSE;

    switch (ei) {

        case EI_METHOD_ENTRY:

            if (!isMethodNative(method)) {

                jvmtiError error;

                jlocation start;

                jlocation end;

                error = methodLocation(method, &start, &end);

                if (error == JVMTI_ERROR_NONE) {

                    deferring = isBreakpointSet(clazz, method, start) ||

                                threadControl_getInstructionStepMode(thread)

                                    == JVMTI_ENABLE;

                    if (!deferring) {

                        threadControl_saveCLEInfo(env, thread, ei,

                                                  clazz, method, start);

                    }

                }

            }

            break;

        case EI_SINGLE_STEP:

            deferring = isBreakpointSet(clazz, method, location);

            if (!deferring) {

                threadControl_saveCLEInfo(env, thread, ei,

                                          clazz, method, location);

            }

            break;

        default:

            break;

    }

    /* TO DO: Once JVMTI supports a way to know if we're

     * at the end of a method, we should check here for

     * break and step events which precede a method exit

     * event.

     */

    return deferring;

}

/* Handle phase 2 of the co-located events policy. See detailed

 * comments in deferEventReport() above.

 */

static jboolean

skipEventReport(JNIEnv *env, jthread thread, EventIndex ei,

                        jclass clazz, jmethodID method, jlocation location)

{

    jboolean skipping = JNI_FALSE;

    if (ei == EI_BREAKPOINT) {

        if (threadControl_cmpCLEInfo(env, thread, clazz, method, location)) {

            LOG_MISC(("Co-located breakpoint event found: "

                "%s,thread=%p,clazz=%p,method=%p,location=%d",

                eventText(ei), thread, clazz, method, location));

            skipping = JNI_TRUE;

        }

    }

    threadControl_clearCLEInfo(env, thread);

    return skipping;

}

static void

reportEvents(JNIEnv *env, jbyte sessionID, jthread thread, EventIndex ei,

             jclass clazz, jmethodID method, jlocation location,

             struct bag *eventBag)

{

    jbyte suspendPolicy;

    jboolean invoking;

    if (bagSize(eventBag) < 1) {

        return;

    }

    /*

     * Never report events before initialization completes

     */

    if (!debugInit_isInitComplete()) {

        return;

    }

    /*

     * Check to see if we should skip reporting this event due to

     * co-location of events policy.

     */

    if (thread != NULL &&

           skipEventReport(env, thread, ei, clazz, method, location)) {

        LOG_MISC(("event report being skipped: "

            "ei=%s,thread=%p,clazz=%p,method=%p,location=%d",

            eventText(ei), thread, clazz, method, location));

        bagDeleteAll(eventBag);

        return;

    }

    /* We delay the reporting of some events so that they can be

     * properly grouped into event sets with upcoming events. If

     * the reporting is to be deferred, the event commands remain

     * in the event bag until a subsequent event occurs.  Event is

     * NULL for synthetic events (e.g. unload).

     */

    if (thread == NULL

         || !deferEventReport(env, thread, ei,

                        clazz, method, location)) {

        struct bag *completedBag = bagDup(eventBag);

        bagDeleteAll(eventBag);

        if (completedBag == NULL) {

            /*

             * TO DO: Report, but don't terminate?

             */

            return;

        } else {

            suspendPolicy = eventHelper_reportEvents(sessionID, completedBag);

            if (thread != NULL && suspendPolicy != JDWP_SUSPEND_POLICY(NONE)) {

                do {

                    /* The events have been reported and this

                     * thread is about to continue, but it may

                     * requested method invocation. If so, we do

                     * the invoke now and then stop again waiting

                     * for another continue. By then another

                     * invoke request can be in place, so there is

                     * a loop around this code.

                     */

                    invoking = invoker_doInvoke(thread);

                    if (invoking) {

                        eventHelper_reportInvokeDone(sessionID, thread);

                    }

                } while (invoking);

            }

            bagDestroyBag(completedBag);

        }

    }

}

/* A bagEnumerateFunction.  Create a synthetic class unload event

 * for every class no longer present.  Analogous to event_callback

 * combined with a handler in a unload specific (no event

 * structure) kind of way.

 */

static jboolean

synthesizeUnloadEvent(void *signatureVoid, void *envVoid)

{

    JNIEnv *env = (JNIEnv *)envVoid;

    char *signature = *(char **)signatureVoid;

    char *classname;

    HandlerNode *node;

    jbyte eventSessionID = currentSessionID;

    struct bag *eventBag = eventHelper_createEventBag();

    if (eventBag == NULL) {

        /* TO DO: Report, but don't die

         */

        JDI_ASSERT(eventBag != NULL);

    }

    /* Signature needs to last, so convert extra copy to

     * classname

     */

    classname = jvmtiAllocate((int)strlen(signature)+1);

    (void)strcpy(classname, signature);

    convertSignatureToClassname(classname);

    debugMonitorEnter(handlerLock);

    node = getHandlerChain(EI_GC_FINISH)->first;

    while (node != NULL) {

        /* save next so handlers can remove themselves */

        HandlerNode *next = NEXT(node);

        jboolean shouldDelete;

        if (eventFilterRestricted_passesUnloadFilter(env, classname,

                                                     node,

                                                     &shouldDelete)) {

            /* There may be multiple handlers, the signature will

             * be freed when the event helper thread has written

             * it.  So each event needs a separate allocation.

             */

            char *durableSignature = jvmtiAllocate((int)strlen(signature)+1);

            (void)strcpy(durableSignature, signature);

            eventHelper_recordClassUnload(node->handlerID,

                                          durableSignature,

                                          eventBag);

        }

        if (shouldDelete) {

            /* We can safely free the node now that we are done

             * using it.

             */

            (void)freeHandler(node);

        }

        node = next;

    }

    debugMonitorExit(handlerLock);

    if (eventBag != NULL) {

        reportEvents(env, eventSessionID, (jthread)NULL, 0,

                            (jclass)NULL, (jmethodID)NULL, 0, eventBag);

        /*

         * bag was created locally, destroy it here.

         */

        bagDestroyBag(eventBag);

    }