// Copyright 2019 Google LLC. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Implementation file for the sandbox2::Sandbox class.

#include "sandboxed_api/sandbox2/sandbox2.h"

#include <csignal>
#include <memory>
#include <string>

#include "absl/memory/memory.h"
#include "absl/synchronization/blocking_counter.h"
#include "sandboxed_api/sandbox2/monitor.h"
#include "sandboxed_api/sandbox2/result.h"
#include "sandboxed_api/util/canonical_errors.h"

namespace sandbox2 {

Sandbox2::~Sandbox2() {
  if (monitor_thread_ && monitor_thread_->joinable()) {
    monitor_thread_->join();
  }
}

sapi::StatusOr<Result> Sandbox2::AwaitResultWithTimeout(
    absl::Duration timeout) {
  CHECK(monitor_ != nullptr) << "Sandbox was not launched yet";
  CHECK(monitor_thread_ != nullptr) << "Sandbox was already waited on";

  absl::MutexLock lock(&monitor_->done_mutex_);
  auto done = monitor_->done_mutex_.AwaitWithTimeout(
      absl::Condition(monitor_.get(), &Monitor::IsDone), timeout);
  if (!done) {
    return ::sapi::DeadlineExceededError(
        "Sandbox did not finish within timeout");
  }
  monitor_thread_->join();

  CHECK(IsTerminated()) << "Monitor did not terminate";

  // Reset the Monitor Thread object to its initial state, as to mark that this
  // object cannot be used anymore to control behavior of the sandboxee (e.g.
  // via signals).
  monitor_thread_.reset(nullptr);

  VLOG(1) << "Final execution status: " << monitor_->result_.ToString();
  CHECK(monitor_->result_.final_status() != Result::UNSET);
  return std::move(monitor_->result_);
}

Result Sandbox2::AwaitResult() {
  return AwaitResultWithTimeout(absl::InfiniteDuration()).ValueOrDie();
}

bool Sandbox2::RunAsync() {
  Launch();

  // If the sandboxee setup failed we return 'false' here.
  if (monitor_->IsDone() &&
      monitor_->result_.final_status() == Result::SETUP_ERROR) {
    return false;
  }
  return true;
}

void Sandbox2::Kill() {
  CHECK(monitor_ != nullptr) << "Sandbox was not launched yet";

  // The sandboxee (and its monitoring thread) are already gone. Ignore the
  // request instead of panic'ing in such case.
  if (monitor_thread_ == nullptr) {
    return;
  }

  pthread_kill(monitor_thread_->native_handle(), Monitor::kExternalKillSignal);
}

void Sandbox2::DumpStackTrace() {
  CHECK(monitor_ != nullptr) << "Sandbox was not launched yet";

  if (monitor_thread_ == nullptr) {
    return;
  }

  pthread_kill(monitor_thread_->native_handle(), Monitor::kDumpStackSignal);
}

bool Sandbox2::IsTerminated() const {
  CHECK(monitor_ != nullptr) << "Sandbox was not launched yet";

  return monitor_->IsDone();
}

void Sandbox2::SetWallTimeLimit(time_t limit) const {
  CHECK(monitor_ != nullptr) << "Sandbox was not launched yet";

  if (monitor_thread_ == nullptr) {
    return;
  }

  union sigval v;
  v.sival_int = static_cast<int>(limit);

  pthread_sigqueue(monitor_thread_->native_handle(), Monitor::kTimerSetSignal,
                   v);
}

void Sandbox2::Launch() {
  monitor_ =
      absl::make_unique<Monitor>(executor_.get(), policy_.get(), notify_.get());
  monitor_thread_ =
      absl::make_unique<std::thread>(&Monitor::Run, monitor_.get());

  // Wait for the Monitor to set-up the sandboxee correctly (or fail while
  // doing that). From here on, it is safe to use the IPC object for
  // non-sandbox-related data exchange.
  monitor_->setup_counter_->Wait();
}

}  // namespace sandbox2