gecko/dom/bluetooth/BluetoothService.cpp

/* -*- Mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; tab-width: 40 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "base/basictypes.h"

#include "BluetoothService.h"

#include "BluetoothManager.h"
#include "BluetoothParent.h"
#include "BluetoothReplyRunnable.h"
#include "BluetoothServiceChildProcess.h"

#include "jsapi.h"
#include "mozilla/Services.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/unused.h"
#include "mozilla/Util.h"
#include "mozilla/dom/ContentParent.h"
#include "mozilla/dom/bluetooth/BluetoothTypes.h"
#include "mozilla/ipc/UnixSocket.h"
#include "nsContentUtils.h"
#include "nsIDOMDOMRequest.h"
#include "nsIObserverService.h"
#include "nsISettingsService.h"
#include "nsISystemMessagesInternal.h"
#include "nsITimer.h"
#include "nsThreadUtils.h"
#include "nsXPCOM.h"
#include "nsXPCOMCIDInternal.h"
#include "nsXULAppAPI.h"

#if defined(MOZ_B2G_BT)
# if defined(MOZ_BLUETOOTH_GONK)
#  include "BluetoothGonkService.h"
# elif defined(MOZ_BLUETOOTH_DBUS)
#  include "BluetoothDBusService.h"
# else
#  error No_suitable_backend_for_bluetooth!
# endif
#endif

#define MOZSETTINGS_CHANGED_ID "mozsettings-changed"
#define BLUETOOTH_ENABLED_SETTING "bluetooth.enabled"

#define DEFAULT_SHUTDOWN_TIMER_MS 5000

using namespace mozilla;
using namespace mozilla::dom;
USING_BLUETOOTH_NAMESPACE

namespace {

StaticRefPtr<BluetoothService> gBluetoothService;

bool gInShutdown = false;

bool
IsMainProcess()
{
  return XRE_GetProcessType() == GeckoProcessType_Default;
}

PLDHashOperator
RemoveAllSignalHandlers(const nsAString& aKey,
                        nsAutoPtr<BluetoothSignalObserverList>& aData,
                        void* aUserArg)
{
  aData->RemoveObserver(static_cast<BluetoothSignalObserver*>(aUserArg));
  return aData->Length() ? PL_DHASH_NEXT : PL_DHASH_REMOVE;
}

void
ShutdownTimeExceeded(nsITimer* aTimer, void* aClosure)
{
  MOZ_ASSERT(NS_IsMainThread());
  *static_cast<bool*>(aClosure) = true;
}

void
GetAllBluetoothActors(InfallibleTArray<BluetoothParent*>& aActors)
{
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(aActors.IsEmpty());

  nsAutoTArray<ContentParent*, 20> contentActors;
  ContentParent::GetAll(contentActors);

  for (uint32_t contentIndex = 0;
       contentIndex < contentActors.Length();
       contentIndex++) {
    MOZ_ASSERT(contentActors[contentIndex]);

    AutoInfallibleTArray<PBluetoothParent*, 5> bluetoothActors;
    contentActors[contentIndex]->ManagedPBluetoothParent(bluetoothActors);

    for (uint32_t bluetoothIndex = 0;
         bluetoothIndex < bluetoothActors.Length();
         bluetoothIndex++) {
      MOZ_ASSERT(bluetoothActors[bluetoothIndex]);

      BluetoothParent* actor =
        static_cast<BluetoothParent*>(bluetoothActors[bluetoothIndex]);
      aActors.AppendElement(actor);
    }
  }
}

} // anonymous namespace

class BluetoothService::ToggleBtAck : public nsRunnable
{
public:
  ToggleBtAck(bool aEnabled)
    : mEnabled(aEnabled)
  {
    MOZ_ASSERT(!NS_IsMainThread());
  }

  NS_IMETHOD Run()
  {
    MOZ_ASSERT(NS_IsMainThread());

    if (!gBluetoothService) {
      return NS_OK;
    }

    if (!gInShutdown) {
      // Notify all the managers about the state change.
      gBluetoothService->SetEnabled(mEnabled);
    }

    if (!mEnabled || gInShutdown) {
      // Shut down the command thread if it still exists.
      if (gBluetoothService->mBluetoothCommandThread) {
        nsCOMPtr<nsIThread> thread;
        gBluetoothService->mBluetoothCommandThread.swap(thread);
        if (NS_FAILED(thread->Shutdown())) {
          NS_WARNING("Failed to shut down the bluetooth command thread!");
        }
      }

      if (gInShutdown) {
        gBluetoothService = nullptr;
      }
    }

    return NS_OK;
  }

private:
  bool mEnabled;
};

class BluetoothService::ToggleBtTask : public nsRunnable
{
public:
  ToggleBtTask(bool aEnabled)
    : mEnabled(aEnabled)
  {
    MOZ_ASSERT(NS_IsMainThread());
  }

  NS_IMETHOD Run()
  {
    MOZ_ASSERT(!NS_IsMainThread());

    if (mEnabled) {
      if (NS_FAILED(gBluetoothService->StartInternal())) {
        NS_WARNING("Bluetooth service failed to start!");
        mEnabled = !mEnabled;
      }
    }
    else if (NS_FAILED(gBluetoothService->StopInternal())) {
      NS_WARNING("Bluetooth service failed to stop!");
      mEnabled = !mEnabled;
    }

    nsCOMPtr<nsIRunnable> ackTask = new BluetoothService::ToggleBtAck(mEnabled);
    if (NS_FAILED(NS_DispatchToMainThread(ackTask))) {
      NS_WARNING("Failed to dispatch to main thread!");
    }

    return NS_OK;
  }

private:
  bool mEnabled;
};

class BluetoothService::StartupTask : public nsISettingsServiceCallback
{
public:
  NS_DECL_ISUPPORTS

  NS_IMETHOD Handle(const nsAString& aName, const jsval& aResult, JSContext* aCx)
  {
    MOZ_ASSERT(NS_IsMainThread());

    if (!aResult.isBoolean()) {
      NS_WARNING("Setting for '" BLUETOOTH_ENABLED_SETTING "' is not a boolean!");
      return NS_OK;
    }

    // It is theoretically possible to shut down before the first settings check
    // has completed (though extremely unlikely).
    if (gBluetoothService) {
      return gBluetoothService->HandleStartupSettingsCheck(aResult.toBoolean());
    }

    return NS_OK;
  }

  NS_IMETHOD HandleError(const nsAString& aName, JSContext* aCx)
  {
    NS_WARNING("Unable to get value for '" BLUETOOTH_ENABLED_SETTING "'");
    return NS_OK;
  }
};

NS_IMPL_ISUPPORTS1(BluetoothService::StartupTask, nsISettingsServiceCallback);

NS_IMPL_ISUPPORTS1(BluetoothService, nsIObserver)

BluetoothService::~BluetoothService()
{
  Cleanup();
}

// static
BluetoothService*
BluetoothService::Create()
{
#if defined(MOZ_B2G_BT)
  if (!IsMainProcess()) {
    return BluetoothServiceChildProcess::Create();
  }
#endif

#if defined(MOZ_BLUETOOTH_GONK)
  return new BluetoothGonkService();
#elif defined(MOZ_BLUETOOTH_DBUS)
  return new BluetoothDBusService();
#endif
  NS_WARNING("No platform support for bluetooth!");
  return nullptr;
}

bool
BluetoothService::Init()
{
  MOZ_ASSERT(NS_IsMainThread());

  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
  NS_ENSURE_TRUE(obs, false);

  if (NS_FAILED(obs->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID,
                                 false))) {
    NS_WARNING("Failed to add shutdown observer!");
    return false;
  }

  // Only the main process should observe bluetooth settings changes.
  if (IsMainProcess() &&
      NS_FAILED(obs->AddObserver(this, MOZSETTINGS_CHANGED_ID, false))) {
    NS_WARNING("Failed to add settings change observer!");
    return false;
  }

  mRegisteredForLocalAgent = true;

  return true;
}

void
BluetoothService::Cleanup()
{
  MOZ_ASSERT(NS_IsMainThread());

  if (mRegisteredForLocalAgent) {
    UnregisterBluetoothSignalHandler(NS_LITERAL_STRING(LOCAL_AGENT_PATH), this);
    mRegisteredForLocalAgent = false;
  }

  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
  if (obs &&
      (NS_FAILED(obs->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) ||
       NS_FAILED(obs->RemoveObserver(this, MOZSETTINGS_CHANGED_ID)))) {
    NS_WARNING("Can't unregister observers!");
  }
}

void
BluetoothService::RegisterBluetoothSignalHandler(const nsAString& aNodeName,
                                                 BluetoothSignalObserver* aHandler)
{
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(aHandler);

  BluetoothSignalObserverList* ol;
  if (!mBluetoothSignalObserverTable.Get(aNodeName, &ol)) {
    ol = new BluetoothSignalObserverList();
    mBluetoothSignalObserverTable.Put(aNodeName, ol);
  }
  ol->AddObserver(aHandler);
}

void
BluetoothService::UnregisterBluetoothSignalHandler(const nsAString& aNodeName,
                                                   BluetoothSignalObserver* aHandler)
{
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(aHandler);

  BluetoothSignalObserverList* ol;
  if (mBluetoothSignalObserverTable.Get(aNodeName, &ol)) {
    ol->RemoveObserver(aHandler);
    if (ol->Length() == 0) {
      mBluetoothSignalObserverTable.Remove(aNodeName);
    }
  }
  else {
    NS_WARNING("Node was never registered!");
  }
}

void
BluetoothService::UnregisterAllSignalHandlers(BluetoothSignalObserver* aHandler)
{
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(aHandler);

  mBluetoothSignalObserverTable.Enumerate(RemoveAllSignalHandlers, aHandler);
}

void
BluetoothService::DistributeSignal(const BluetoothSignal& aSignal)
{
  MOZ_ASSERT(NS_IsMainThread());
  // Notify observers that a message has been sent
  BluetoothSignalObserverList* ol;
  if (!mBluetoothSignalObserverTable.Get(aSignal.path(), &ol)) {
#if DEBUG
    nsAutoCString msg("No observer registered for path ");
    msg.Append(NS_ConvertUTF16toUTF8(aSignal.path()));
    NS_WARNING(msg.get());
#endif
    return;
  }
  MOZ_ASSERT(ol->Length());
  ol->Broadcast(aSignal);
}

nsresult
BluetoothService::StartStopBluetooth(bool aStart)
{
  MOZ_ASSERT(NS_IsMainThread());

  if (gInShutdown) {
    if (aStart) {
      // Don't try to start if we're already shutting down.
      MOZ_ASSERT(false, "Start called while in shutdown!");
      return NS_ERROR_FAILURE;
    }

    if (!mBluetoothCommandThread) {
      // Don't create a new thread after we've begun shutdown since bluetooth
      // can't be running.
      return NS_OK;
    }
  }

  nsresult rv;

  if (!mBluetoothCommandThread) {
    MOZ_ASSERT(!gInShutdown);

    rv = NS_NewNamedThread("BluetoothCmd",
                           getter_AddRefs(mBluetoothCommandThread));
    NS_ENSURE_SUCCESS(rv, rv);
  }

  if (aStart) {
    RegisterBluetoothSignalHandler(NS_LITERAL_STRING(LOCAL_AGENT_PATH), this);
    RegisterBluetoothSignalHandler(NS_LITERAL_STRING(REMOTE_AGENT_PATH), this);

    BluetoothManagerList::ForwardIterator iter(mLiveManagers);
    while (iter.HasMore()) {
      RegisterBluetoothSignalHandler(NS_LITERAL_STRING("/"), (BluetoothSignalObserver*)iter.GetNext());
    }
  }

  nsCOMPtr<nsIRunnable> runnable = new ToggleBtTask(aStart);
  rv = mBluetoothCommandThread->Dispatch(runnable, NS_DISPATCH_NORMAL);
  NS_ENSURE_SUCCESS(rv, rv);

  return NS_OK;
}

void
BluetoothService::SetEnabled(bool aEnabled)
{
  MOZ_ASSERT(NS_IsMainThread());

  if (aEnabled == mEnabled) {
    // Nothing to do, maybe something failed.
    return;
  }

  mEnabled = aEnabled;

  AutoInfallibleTArray<BluetoothParent*, 10> childActors;
  GetAllBluetoothActors(childActors);

  for (uint32_t index = 0; index < childActors.Length(); index++) {
    unused << childActors[index]->SendEnabled(aEnabled);
  }

  BluetoothManagerList::ForwardIterator iter(mLiveManagers);
  while (iter.HasMore()) {
    if (NS_FAILED(iter.GetNext()->FireEnabledDisabledEvent(aEnabled))) {
      NS_WARNING("FireEnabledDisabledEvent failed!");
    }
  }
}

nsresult
BluetoothService::HandleStartup()
{
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(!mSettingsCheckInProgress);

  nsCOMPtr<nsISettingsService> settings =
    do_GetService("@mozilla.org/settingsService;1");
  NS_ENSURE_TRUE(settings, NS_ERROR_UNEXPECTED);

  nsCOMPtr<nsISettingsServiceLock> settingsLock;
  nsresult rv = settings->CreateLock(getter_AddRefs(settingsLock));
  NS_ENSURE_SUCCESS(rv, rv);

  nsRefPtr<StartupTask> callback = new StartupTask();
  rv = settingsLock->Get(BLUETOOTH_ENABLED_SETTING, callback);
  NS_ENSURE_SUCCESS(rv, rv);

  mSettingsCheckInProgress = true;
  return NS_OK;
}

nsresult
BluetoothService::HandleStartupSettingsCheck(bool aEnable)
{
  MOZ_ASSERT(NS_IsMainThread());

  if (!mSettingsCheckInProgress) {
    // Somehow the enabled setting was changed before our first settings check
    // completed. Don't do anything.
    return NS_OK;
  }

  MOZ_ASSERT(!IsEnabled());

  if (aEnable) {
    return StartStopBluetooth(true);
  }

  return NS_OK;
}

nsresult
BluetoothService::HandleSettingsChanged(const nsAString& aData)
{
  MOZ_ASSERT(NS_IsMainThread());

  // The string that we're interested in will be a JSON string that looks like:
  //  {"key":"bluetooth.enabled","value":true}

  JSContext* cx = nsContentUtils::GetSafeJSContext();
  if (!cx) {
    return NS_OK;
  }

  JS::Value val;
  if (!JS_ParseJSON(cx, aData.BeginReading(), aData.Length(), &val)) {
    return JS_ReportPendingException(cx) ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
  }

  if (!val.isObject()) {
    return NS_OK;
  }

  JSObject& obj(val.toObject());

  JS::Value key;
  if (!JS_GetProperty(cx, &obj, "key", &key)) {
    MOZ_ASSERT(!JS_IsExceptionPending(cx));
    return NS_ERROR_OUT_OF_MEMORY;
  }

  if (!key.isString()) {
    return NS_OK;
  }

  JSBool match;
  if (!JS_StringEqualsAscii(cx, key.toString(), BLUETOOTH_ENABLED_SETTING,
                            &match)) {
    MOZ_ASSERT(!JS_IsExceptionPending(cx));
    return NS_ERROR_OUT_OF_MEMORY;
  }

  if (!match) {
    return NS_OK;
  }

  JS::Value value;
  if (!JS_GetProperty(cx, &obj, "value", &value)) {
    MOZ_ASSERT(!JS_IsExceptionPending(cx));
    return NS_ERROR_OUT_OF_MEMORY;
  }

  if (!value.isBoolean()) {
    MOZ_ASSERT(false, "Expecting a boolean for 'bluetooth.enabled'!");
    return NS_ERROR_UNEXPECTED;
  }

  if (mSettingsCheckInProgress) {
    // Somehow the setting for bluetooth has been flipped before our first
    // settings check completed. Flip this flag so that we ignore the result
    // of that check whenever it finishes.
    mSettingsCheckInProgress = false;
  }

  if (value.toBoolean() == IsEnabled()) {
    // Nothing to do here.
    return NS_OK;
  }

  nsresult rv;

  if (IsEnabled()) {
    rv = StartStopBluetooth(false);
    NS_ENSURE_SUCCESS(rv, rv);

    return NS_OK;
  }

  rv = StartStopBluetooth(true);
  NS_ENSURE_SUCCESS(rv, rv);

  return NS_OK;
}

nsresult
BluetoothService::HandleShutdown()
{
  MOZ_ASSERT(NS_IsMainThread());

  // This is a two phase shutdown. First we notify all child processes that
  // bluetooth is going away, and then we wait for them to acknowledge. Then we
  // close down all the bluetooth machinery.

  gInShutdown = true;

  Cleanup();

  AutoInfallibleTArray<BluetoothParent*, 10> childActors;
  GetAllBluetoothActors(childActors);

  if (!childActors.IsEmpty()) {
    // Notify child processes that they should stop using bluetooth now.
    for (uint32_t index = 0; index < childActors.Length(); index++) {
      childActors[index]->BeginShutdown();
    }

    // Create a timer to ensure that we don't wait forever for a child process
    // or the bluetooth threads to finish. If we don't get a timer or can't use
    // it for some reason then we skip all the waiting entirely since we really
    // can't afford to hang on shutdown.
    nsCOMPtr<nsITimer> timer = do_CreateInstance(NS_TIMER_CONTRACTID);
    MOZ_ASSERT(timer);

    if (timer) {
      bool timeExceeded = false;

      if (NS_SUCCEEDED(timer->InitWithFuncCallback(ShutdownTimeExceeded,
                                                   &timeExceeded,
                                                   DEFAULT_SHUTDOWN_TIMER_MS,
                                                   nsITimer::TYPE_ONE_SHOT))) {
        nsIThread* currentThread = NS_GetCurrentThread();
        MOZ_ASSERT(currentThread);

        // Wait for those child processes to acknowledge.
        while (!timeExceeded && !childActors.IsEmpty()) {
          if (!NS_ProcessNextEvent(currentThread)) {
            MOZ_ASSERT(false, "Something horribly wrong here!");
            break;
          }
          GetAllBluetoothActors(childActors);
        }

        if (NS_FAILED(timer->Cancel())) {
          MOZ_NOT_REACHED("Failed to cancel shutdown timer, this will crash!");
        }
      }
      else {
        MOZ_ASSERT(false, "Failed to initialize shutdown timer!");
      }
    }
  }

  if (IsEnabled() && NS_FAILED(StartStopBluetooth(false))) {
    MOZ_ASSERT(false, "Failed to deliver stop message!");
  }

  return NS_OK;
}

void
BluetoothService::RegisterManager(BluetoothManager* aManager)
{
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(aManager);
  MOZ_ASSERT(!mLiveManagers.Contains(aManager));

  mLiveManagers.AppendElement(aManager);
  RegisterBluetoothSignalHandler(aManager->GetPath(), aManager);
}

void
BluetoothService::UnregisterManager(BluetoothManager* aManager)
{
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(aManager);
  MOZ_ASSERT(mLiveManagers.Contains(aManager));

  UnregisterBluetoothSignalHandler(aManager->GetPath(), aManager);
  mLiveManagers.RemoveElement(aManager);
}

// static
BluetoothService*
BluetoothService::Get()
{
  MOZ_ASSERT(NS_IsMainThread());

  // If we already exist, exit early
  if (gBluetoothService) {
    return gBluetoothService;
  }

  // If we're in shutdown, don't create a new instance
  if (gInShutdown) {
    NS_WARNING("BluetoothService can't be created during shutdown");
    return nullptr;
  }

  // Create new instance, register, return
  nsRefPtr<BluetoothService> service = BluetoothService::Create();
  NS_ENSURE_TRUE(service, nullptr);

  if (!service->Init()) {
    service->Cleanup();
    return nullptr;
  }

  gBluetoothService = service;
  return gBluetoothService;
}

nsresult
BluetoothService::Observe(nsISupports* aSubject, const char* aTopic,
                          const PRUnichar* aData)
{
  MOZ_ASSERT(NS_IsMainThread());

  if (!strcmp(aTopic, "profile-after-change")) {
    return HandleStartup();
  }

  if (!strcmp(aTopic, MOZSETTINGS_CHANGED_ID)) {
    return HandleSettingsChanged(nsDependentString(aData));
  }

  if (!strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) {
    return HandleShutdown();
  }

  MOZ_ASSERT(false, "BluetoothService got unexpected topic!");
  return NS_ERROR_UNEXPECTED;
}

bool
SetJsObject(JSContext* aContext,
            JSObject* aObj,
            const InfallibleTArray<BluetoothNamedValue>& aData)
{
  for (uint32_t i = 0; i < aData.Length(); i++) {
    jsval v;
    if (aData[i].value().type() == BluetoothValue::TnsString) {
      nsString data = aData[i].value().get_nsString();
      JSString* JsData = JS_NewStringCopyN(aContext,
                                           NS_ConvertUTF16toUTF8(data).get(),
                                           data.Length());
      NS_ENSURE_TRUE(JsData, NS_ERROR_OUT_OF_MEMORY);
      v = STRING_TO_JSVAL(JsData);
    } else if (aData[i].value().type() == BluetoothValue::Tuint32_t) {
      int data = aData[i].value().get_uint32_t();
      v = INT_TO_JSVAL(data);
    } else if (aData[i].value().type() == BluetoothValue::Tbool) {
      bool data = aData[i].value().get_bool();
      v = BOOLEAN_TO_JSVAL(data);
    } else {
      NS_WARNING("SetJsObject: Parameter is not handled");
    }

    if (!JS_SetProperty(aContext, aObj,
                        NS_ConvertUTF16toUTF8(aData[i].name()).get(),
                        &v)) {
      return false;
    }
  }
  return true;
}

void
BluetoothService::Notify(const BluetoothSignal& aData)
{
  InfallibleTArray<BluetoothNamedValue> arr = aData.value().get_ArrayOfBluetoothNamedValue();
  nsString type;

  JSContext* cx = nsContentUtils::GetSafeJSContext();
  NS_ASSERTION(!::JS_IsExceptionPending(cx),
               "Shouldn't get here when an exception is pending!");

  JSAutoRequest jsar(cx);
  JSObject* obj = JS_NewObject(cx, NULL, NULL, NULL);
  if (!obj) {
    NS_WARNING("Failed to new JSObject for system message!");
    return;
  }

  bool ok = SetJsObject(cx, obj, arr);
  if (!ok) {
    NS_WARNING("Failed to set properties of system message!");
    return;
  }

  if (aData.name().EqualsLiteral("RequestConfirmation")) {
    NS_ASSERTION(arr.Length() == 3, "RequestConfirmation: Wrong length of parameters");
    type.AssignLiteral("bluetooth-requestconfirmation");
  } else if (aData.name().EqualsLiteral("RequestPinCode")) {
    NS_ASSERTION(arr.Length() == 2, "RequestPinCode: Wrong length of parameters");
    type.AssignLiteral("bluetooth-requestpincode");
  } else if (aData.name().EqualsLiteral("RequestPasskey")) {
    NS_ASSERTION(arr.Length() == 2, "RequestPinCode: Wrong length of parameters");
    type.AssignLiteral("bluetooth-requestpasskey");
  } else if (aData.name().EqualsLiteral("Authorize")) {
    NS_ASSERTION(arr.Length() == 2, "Authorize: Wrong length of parameters");
    type.AssignLiteral("bluetooth-authorize");
  } else if (aData.name().EqualsLiteral("Cancel")) {
    NS_ASSERTION(arr.Length() == 0, "Cancel: Wrong length of parameters");
    type.AssignLiteral("bluetooth-cancel");
  } else if (aData.name().EqualsLiteral("PairedStatusChanged")) {
    NS_ASSERTION(arr.Length() == 1, "PairedStatusChagned: Wrong length of parameters");
    type.AssignLiteral("bluetooth-pairedstatuschanged");
  } else {
#ifdef DEBUG
    nsCString warningMsg;
    warningMsg.AssignLiteral("Not handling service signal: ");
    warningMsg.Append(NS_ConvertUTF16toUTF8(aData.name()));
    NS_WARNING(warningMsg.get());
#endif
  }

  nsCOMPtr<nsISystemMessagesInternal> systemMessenger =
    do_GetService("@mozilla.org/system-message-internal;1");

  if (!systemMessenger) {
    NS_WARNING("Failed to get SystemMessenger service!");
    return;
  }
  systemMessenger->BroadcastMessage(type, OBJECT_TO_JSVAL(obj));
}