// Copyright (c) 2011 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.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/process_util.h"
#include "base/win/windows_version.h"

namespace base {

void Process::Close() {
  if (!process_)
    return;

  // Don't call CloseHandle on a pseudo-handle.
  if (process_ != ::GetCurrentProcess())
    ::CloseHandle(process_);

  process_ = NULL;
}

void Process::Terminate(int result_code) {
  if (!process_)
    return;

  // Call NtTerminateProcess directly, without going through the import table,
  // which might have been hooked with a buggy replacement by third party
  // software. http://crbug.com/81449.
  HMODULE module = GetModuleHandle(L"ntdll.dll");
  typedef UINT (WINAPI *TerminateProcessPtr)(HANDLE handle, UINT code);
  TerminateProcessPtr terminate_process = reinterpret_cast<TerminateProcessPtr>(
      GetProcAddress(module, "NtTerminateProcess"));
  terminate_process(process_, result_code);
}

bool Process::IsProcessBackgrounded() const {
  if (!process_)
    return false;  // Failure case.
  DWORD priority = GetPriority();
  if (priority == 0)
    return false;  // Failure case.
  return ((priority == BELOW_NORMAL_PRIORITY_CLASS) ||
          (priority == IDLE_PRIORITY_CLASS));
}

bool Process::SetProcessBackgrounded(bool value) {
  if (!process_)
    return false;
  // Vista and above introduce a real background mode, which not only
  // sets the priority class on the threads but also on the IO generated
  // by it. Unfortunately it can only be set for the calling process.
  DWORD priority;
  if ((base::win::GetVersion() >= base::win::VERSION_VISTA) &&
      (process_ == ::GetCurrentProcess())) {
    priority = value ? PROCESS_MODE_BACKGROUND_BEGIN :
                       PROCESS_MODE_BACKGROUND_END;
  } else {
    priority = value ? BELOW_NORMAL_PRIORITY_CLASS : NORMAL_PRIORITY_CLASS;
  }

  return (::SetPriorityClass(process_, priority) != 0);
}

ProcessId Process::pid() const {
  if (process_ == 0)
    return 0;

  return GetProcId(process_);
}

bool Process::is_current() const {
  return process_ == GetCurrentProcess();
}

// static
Process Process::Current() {
  return Process(::GetCurrentProcess());
}

// static
bool Process::CanBackgroundProcesses() {
  return true;
}

int Process::GetPriority() const {
  DCHECK(process_);
  return ::GetPriorityClass(process_);
}

}  // namespace base