/*

 * Copyright (c) 2003, 2017, 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 "precompiled.hpp"

#include "classfile/systemDictionary.hpp"

#include "interpreter/interpreter.hpp"

#include "jvmtifiles/jvmtiEnv.hpp"

#include "memory/resourceArea.hpp"

#include "prims/jvmtiEnvThreadState.hpp"

#include "prims/jvmtiEventController.inline.hpp"

#include "prims/jvmtiImpl.hpp"

#include "runtime/handles.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/javaCalls.hpp"

#include "runtime/signature.hpp"

#include "runtime/thread.inline.hpp"

#include "runtime/vframe.hpp"

#include "runtime/vm_operations.hpp"

///////////////////////////////////////////////////////////////

//

// class JvmtiFramePop

//

#ifndef PRODUCT

void JvmtiFramePop::print() {

  tty->print_cr("_frame_number=%d", _frame_number);

}

#endif

///////////////////////////////////////////////////////////////

//

// class JvmtiFramePops - private methods

//

void

JvmtiFramePops::set(JvmtiFramePop& fp) {

  if (_pops->find(fp.frame_number()) < 0) {

    _pops->append(fp.frame_number());

  }

}

void

JvmtiFramePops::clear(JvmtiFramePop& fp) {

  assert(_pops->length() > 0, "No more frame pops");

  _pops->remove(fp.frame_number());

}

int

JvmtiFramePops::clear_to(JvmtiFramePop& fp) {

  int cleared = 0;

  int index = 0;

  while (index < _pops->length()) {

    JvmtiFramePop pop = JvmtiFramePop(_pops->at(index));

    if (pop.above_on_stack(fp)) {

      _pops->remove_at(index);

      ++cleared;

    } else {

      ++index;

    }

  }

  return cleared;

}

///////////////////////////////////////////////////////////////

//

// class JvmtiFramePops - public methods

//

JvmtiFramePops::JvmtiFramePops() {

  _pops = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int> (2, true);

}

JvmtiFramePops::~JvmtiFramePops() {

  // return memory to c_heap.

  delete _pops;

}

#ifndef PRODUCT

void JvmtiFramePops::print() {

  ResourceMark rm;

  int n = _pops->length();

  for (int i=0; i<n; i++) {

    JvmtiFramePop fp = JvmtiFramePop(_pops->at(i));

    tty->print("%d: ", i);

    fp.print();

    tty->cr();

  }

}

#endif

///////////////////////////////////////////////////////////////

//

// class JvmtiEnvThreadState

//

// Instances of JvmtiEnvThreadState hang off of each JvmtiThreadState,

// one per JvmtiEnv.

//

JvmtiEnvThreadState::JvmtiEnvThreadState(JavaThread *thread, JvmtiEnvBase *env) :

  _event_enable() {

  _thread                 = thread;

  _env                    = (JvmtiEnv*)env;

  _next                   = NULL;

  _frame_pops             = NULL;

  _current_bci            = 0;

  _current_method_id      = NULL;

  _breakpoint_posted      = false;

  _single_stepping_posted = false;

  _agent_thread_local_storage_data = NULL;

}

JvmtiEnvThreadState::~JvmtiEnvThreadState()   {

  delete _frame_pops;

  _frame_pops = NULL;

}

// Given that a new (potential) event has come in,

// maintain the current JVMTI location on a per-thread per-env basis

// and use it to filter out duplicate events:

// - instruction rewrites

// - breakpoint followed by single step

// - single step at a breakpoint

void JvmtiEnvThreadState::compare_and_set_current_location(Method* new_method,

                                                           address new_location, jvmtiEvent event) {

  int new_bci = new_location - new_method->code_base();

  // The method is identified and stored as a jmethodID which is safe in this

  // case because the class cannot be unloaded while a method is executing.

  jmethodID new_method_id = new_method->jmethod_id();

  // the last breakpoint or single step was at this same location

  if (_current_bci == new_bci && _current_method_id == new_method_id) {

    switch (event) {

    case JVMTI_EVENT_BREAKPOINT:

      // Repeat breakpoint is complicated. If we previously posted a breakpoint

      // event at this location and if we also single stepped at this location

      // then we skip the duplicate breakpoint.

      _breakpoint_posted = _breakpoint_posted && _single_stepping_posted;

      break;

    case JVMTI_EVENT_SINGLE_STEP:

      // Repeat single step is easy: just don't post it again.

      // If step is pending for popframe then it may not be

      // a repeat step. The new_bci and method_id is same as current_bci

      // and current method_id after pop and step for recursive calls.

      // This has been handled by clearing the location

      _single_stepping_posted = true;

      break;

    default:

      assert(false, "invalid event value passed");

      break;

    }

    return;

  }

  set_current_location(new_method_id, new_bci);

  _breakpoint_posted = false;

  _single_stepping_posted = false;

}

JvmtiFramePops* JvmtiEnvThreadState::get_frame_pops() {

  assert(get_thread() == Thread::current() || SafepointSynchronize::is_at_safepoint(),

         "frame pop data only accessible from same thread or at safepoint");

  if (_frame_pops == NULL) {

    _frame_pops = new JvmtiFramePops();

    assert(_frame_pops != NULL, "_frame_pops != NULL");

  }

  return _frame_pops;

}

bool JvmtiEnvThreadState::has_frame_pops() {

  return _frame_pops == NULL? false : (_frame_pops->length() > 0);

}

void JvmtiEnvThreadState::set_frame_pop(int frame_number) {

  assert(get_thread() == Thread::current() || SafepointSynchronize::is_at_safepoint(),

         "frame pop data only accessible from same thread or at safepoint");

  JvmtiFramePop fpop(frame_number);

  JvmtiEventController::set_frame_pop(this, fpop);

}

void JvmtiEnvThreadState::clear_frame_pop(int frame_number) {

  assert(get_thread() == Thread::current() || SafepointSynchronize::is_at_safepoint(),

         "frame pop data only accessible from same thread or at safepoint");

  JvmtiFramePop fpop(frame_number);

  JvmtiEventController::clear_frame_pop(this, fpop);

}

void JvmtiEnvThreadState::clear_to_frame_pop(int frame_number)  {

  assert(get_thread() == Thread::current() || SafepointSynchronize::is_at_safepoint(),

         "frame pop data only accessible from same thread or at safepoint");

  JvmtiFramePop fpop(frame_number);

  JvmtiEventController::clear_to_frame_pop(this, fpop);

}

bool JvmtiEnvThreadState::is_frame_pop(int cur_frame_number) {

  assert(get_thread() == Thread::current() || SafepointSynchronize::is_at_safepoint(),

         "frame pop data only accessible from same thread or at safepoint");

  if (!get_thread()->is_interp_only_mode() || _frame_pops == NULL) {

    return false;

  }

  JvmtiFramePop fp(cur_frame_number);

  return get_frame_pops()->contains(fp);

}

class VM_GetCurrentLocation : public VM_Operation {

 private:

   JavaThread *_thread;

   jmethodID _method_id;

   int _bci;

 public:

  VM_GetCurrentLocation(JavaThread *thread) {

     _thread = thread;

   }

  VMOp_Type type() const { return VMOp_GetCurrentLocation; }

  void doit() {

    ResourceMark rmark; // _thread != Thread::current()

    RegisterMap rm(_thread, false);

    // There can be a race condition between a VM_Operation reaching a safepoint

    // and the target thread exiting from Java execution.

    // We must recheck the last Java frame still exists.

    if (!_thread->is_exiting() && _thread->has_last_Java_frame()) {

      javaVFrame* vf = _thread->last_java_vframe(&rm);

      assert(vf != NULL, "must have last java frame");

      Method* method = vf->method();

      _method_id = method->jmethod_id();

      _bci = vf->bci();

    } else {

      // Clear current location as the target thread has no Java frames anymore.

      _method_id = (jmethodID)NULL;

      _bci = 0;

    }

  }

  void get_current_location(jmethodID *method_id, int *bci) {

    *method_id = _method_id;

    *bci = _bci;

  }

};

void JvmtiEnvThreadState::reset_current_location(jvmtiEvent event_type, bool enabled) {

  assert(event_type == JVMTI_EVENT_SINGLE_STEP || event_type == JVMTI_EVENT_BREAKPOINT,

         "must be single-step or breakpoint event");

  // Current location is used to detect the following:

  // 1) a breakpoint event followed by single-stepping to the same bci

  // 2) single-step to a bytecode that will be transformed to a fast version

  // We skip to avoid posting the duplicate single-stepping event.

  // If single-stepping is disabled, clear current location so that

  // single-stepping to the same method and bcp at a later time will be

  // detected if single-stepping is enabled at that time (see 4388912).

  // If single-stepping is enabled, set the current location to the

  // current method and bcp. This covers the following type of case,

  // e.g., the debugger stepi command:

  // - bytecode single stepped

  // - SINGLE_STEP event posted and SINGLE_STEP event disabled

  // - SINGLE_STEP event reenabled

  // - bytecode rewritten to fast version

  // If breakpoint event is disabled, clear current location only if

  // single-stepping is not enabled.  Otherwise, keep the thread location

  // to detect any duplicate events.

  if (enabled) {

    // If enabling breakpoint, no need to reset.

    // Can't do anything if empty stack.

    if (event_type == JVMTI_EVENT_SINGLE_STEP && _thread->has_last_Java_frame()) {

      jmethodID method_id;

      int bci;

      // The java thread stack may not be walkable for a running thread

      // so get current location at safepoint.

      VM_GetCurrentLocation op(_thread);

      VMThread::execute(&op);

      op.get_current_location(&method_id, &bci);

      set_current_location(method_id, bci);

    }

  } else if (event_type == JVMTI_EVENT_SINGLE_STEP || !is_enabled(JVMTI_EVENT_SINGLE_STEP)) {

    // If this is to disable breakpoint, also check if single-step is not enabled

    clear_current_location();

  }

}