qBittorrent/src/app/applicationinstancemanager.cpp

/*
 * Bittorrent Client using Qt and libtorrent.
 * Copyright (C) 2019  Vladimir Golovnev <glassez@yandex.ru>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * In addition, as a special exception, the copyright holders give permission to
 * link this program with the OpenSSL project's "OpenSSL" library (or with
 * modified versions of it that use the same license as the "OpenSSL" library),
 * and distribute the linked executables. You must obey the GNU General Public
 * License in all respects for all of the code used other than "OpenSSL".  If you
 * modify file(s), you may extend this exception to your version of the file(s),
 * but you are not obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 */

#include "applicationinstancemanager.h"

#ifdef Q_OS_WIN
#include <windows.h>
#endif

#include <QDebug>
#include <QSharedMemory>

#include "qtlocalpeer/qtlocalpeer.h"

ApplicationInstanceManager::ApplicationInstanceManager(const QString &appId, QObject *parent)
    : QObject {parent}
    , m_peer {new QtLocalPeer {this, appId}}
    , m_isFirstInstance {!m_peer->isClient()}
{
    connect(m_peer, &QtLocalPeer::messageReceived, this, &ApplicationInstanceManager::messageReceived);

#ifdef Q_OS_WIN
    auto sharedMem = new QSharedMemory {appId + QLatin1String {"-shared-memory-key"}, this};
    if (m_isFirstInstance)
    {
        // First instance creates shared memory and store PID
        if (sharedMem->create(sizeof(DWORD)) && sharedMem->lock())
        {
            *(static_cast<DWORD *>(sharedMem->data())) = ::GetCurrentProcessId();
            sharedMem->unlock();
        }
    }
    else
    {
        // Later instances attach to shared memory and retrieve PID
        if (sharedMem->attach() && sharedMem->lock())
        {
            ::AllowSetForegroundWindow(*(static_cast<DWORD *>(sharedMem->data())));
            sharedMem->unlock();
        }
    }

    if (!sharedMem->isAttached())
        qCritical() << "Failed to initialize shared memory: " << sharedMem->errorString();
#endif
}

bool ApplicationInstanceManager::isFirstInstance() const
{
    return m_isFirstInstance;
}

bool ApplicationInstanceManager::sendMessage(const QString &message, const int timeout)
{
    return m_peer->sendMessage(message, timeout);
}

QString ApplicationInstanceManager::appId() const
{
    return m_peer->applicationId();
}