// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/process/kill.h"

#include <windows.h>
#include <io.h>
#include <stdint.h>

#include <algorithm>
#include <utility>

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/process/memory.h"
#include "base/process/process_iterator.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/win/object_watcher.h"

namespace base {

namespace {

// Exit codes with special meanings on Windows.
const DWORD kNormalTerminationExitCode = 0;
const DWORD kDebuggerInactiveExitCode = 0xC0000354;
const DWORD kKeyboardInterruptExitCode = 0xC000013A;
const DWORD kDebuggerTerminatedExitCode = 0x40010004;

// This exit code is used by the Windows task manager when it kills a
// process.  It's value is obviously not that unique, and it's
// surprising to me that the task manager uses this value, but it
// seems to be common practice on Windows to test for it as an
// indication that the task manager has killed something if the
// process goes away.
const DWORD kProcessKilledExitCode = 1;

// Maximum amount of time (in milliseconds) to wait for the process to exit.
static const int kWaitInterval = 2000;

class TimerExpiredTask : public win::ObjectWatcher::Delegate {
 public:
  explicit TimerExpiredTask(Process process);
  ~TimerExpiredTask() override;

  void TimedOut();

  // win::ObjectWatcher::Delegate implementation.
  void OnObjectSignaled(HANDLE object) override;

 private:
  void KillProcess();

  // The process that we are watching.
  Process process_;

  win::ObjectWatcher watcher_;

  DISALLOW_COPY_AND_ASSIGN(TimerExpiredTask);
};

TimerExpiredTask::TimerExpiredTask(Process process)
    : process_(std::move(process)) {
  watcher_.StartWatchingOnce(process_.Handle(), this);
}

TimerExpiredTask::~TimerExpiredTask() {
  TimedOut();
}

void TimerExpiredTask::TimedOut() {
  if (process_.IsValid())
    KillProcess();
}

void TimerExpiredTask::OnObjectSignaled(HANDLE object) {
  process_.Close();
}

void TimerExpiredTask::KillProcess() {
  // Stop watching the process handle since we're killing it.
  watcher_.StopWatching();

  // OK, time to get frisky.  We don't actually care when the process
  // terminates.  We just care that it eventually terminates, and that's what
  // TerminateProcess should do for us. Don't check for the result code since
  // it fails quite often. This should be investigated eventually.
  process_.Terminate(kProcessKilledExitCode, false);

  // Now, just cleanup as if the process exited normally.
  OnObjectSignaled(process_.Handle());
}

}  // namespace

TerminationStatus GetTerminationStatus(ProcessHandle handle, int* exit_code) {
  DWORD tmp_exit_code = 0;

  if (!::GetExitCodeProcess(handle, &tmp_exit_code)) {
    DPLOG(FATAL) << "GetExitCodeProcess() failed";
    if (exit_code) {
      // This really is a random number.  We haven't received any
      // information about the exit code, presumably because this
      // process doesn't have permission to get the exit code, or
      // because of some other cause for GetExitCodeProcess to fail
      // (MSDN docs don't give the possible failure error codes for
      // this function, so it could be anything).  But we don't want
      // to leave exit_code uninitialized, since that could cause
      // random interpretations of the exit code.  So we assume it
      // terminated "normally" in this case.
      *exit_code = kNormalTerminationExitCode;
    }
    // Assume the child has exited normally if we can't get the exit
    // code.
    return TERMINATION_STATUS_NORMAL_TERMINATION;
  }
  if (tmp_exit_code == STILL_ACTIVE) {
    DWORD wait_result = WaitForSingleObject(handle, 0);
    if (wait_result == WAIT_TIMEOUT) {
      if (exit_code)
        *exit_code = wait_result;
      return TERMINATION_STATUS_STILL_RUNNING;
    }

    if (wait_result == WAIT_FAILED) {
      DPLOG(ERROR) << "WaitForSingleObject() failed";
    } else {
      DCHECK_EQ(WAIT_OBJECT_0, wait_result);

      // Strange, the process used 0x103 (STILL_ACTIVE) as exit code.
      NOTREACHED();
    }

    return TERMINATION_STATUS_ABNORMAL_TERMINATION;
  }

  if (exit_code)
    *exit_code = tmp_exit_code;

  switch (tmp_exit_code) {
    case kNormalTerminationExitCode:
      return TERMINATION_STATUS_NORMAL_TERMINATION;
    case kDebuggerInactiveExitCode:  // STATUS_DEBUGGER_INACTIVE.
    case kKeyboardInterruptExitCode:  // Control-C/end session.
    case kDebuggerTerminatedExitCode:  // Debugger terminated process.
    case kProcessKilledExitCode:  // Task manager kill.
      return TERMINATION_STATUS_PROCESS_WAS_KILLED;
    case base::win::kSandboxFatalMemoryExceeded:  // Terminated process due to
                                                  // exceeding the sandbox job
                                                  // object memory limits.
    case base::win::kOomExceptionCode:  // Ran out of memory.
      return TERMINATION_STATUS_OOM;
    default:
      // All other exit codes indicate crashes.
      return TERMINATION_STATUS_PROCESS_CRASHED;
  }
}

bool WaitForProcessesToExit(const FilePath::StringType& executable_name,
                            TimeDelta wait,
                            const ProcessFilter* filter) {
  bool result = true;
  DWORD start_time = GetTickCount();

  NamedProcessIterator iter(executable_name, filter);
  for (const ProcessEntry* entry = iter.NextProcessEntry(); entry;
       entry = iter.NextProcessEntry()) {
    DWORD remaining_wait = static_cast<DWORD>(
        std::max(static_cast<int64_t>(0),
                 wait.InMilliseconds() - (GetTickCount() - start_time)));
    HANDLE process = OpenProcess(SYNCHRONIZE,
                                 FALSE,
                                 entry->th32ProcessID);
    DWORD wait_result = WaitForSingleObject(process, remaining_wait);
    CloseHandle(process);
    result &= (wait_result == WAIT_OBJECT_0);
  }

  return result;
}

bool CleanupProcesses(const FilePath::StringType& executable_name,
                      TimeDelta wait,
                      int exit_code,
                      const ProcessFilter* filter) {
  if (WaitForProcessesToExit(executable_name, wait, filter))
    return true;
  KillProcesses(executable_name, exit_code, filter);
  return false;
}

void EnsureProcessTerminated(Process process) {
  DCHECK(!process.is_current());

  // If already signaled, then we are done!
  if (WaitForSingleObject(process.Handle(), 0) == WAIT_OBJECT_0) {
    return;
  }

  ThreadTaskRunnerHandle::Get()->PostDelayedTask(
      FROM_HERE, Bind(&TimerExpiredTask::TimedOut,
                      Owned(new TimerExpiredTask(std::move(process)))),
      TimeDelta::FromMilliseconds(kWaitInterval));
}

}  // namespace base