signalhandler.cpp

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/*
 * This file is part of the PulseView project.
 *
 * Copyright (C) 2013 Adam Reichold
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include "signalhandler.hpp"

#include <cassert>
#include <csignal>
#include <cstdlib>

#include <sys/socket.h>
#include <unistd.h>

#include <QDebug>
#include <QSocketNotifier>

int SignalHandler::sockets_[2];

bool SignalHandler::prepare_signals()
{
    if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets_) != 0)
        return false;

    struct sigaction sig_action;

    sig_action.sa_handler = SignalHandler::handle_signals;
    sigemptyset(&sig_action.sa_mask);
    sig_action.sa_flags = SA_RESTART;

    if (sigaction(SIGINT, &sig_action, nullptr) != 0 ||
        sigaction(SIGTERM, &sig_action, nullptr) != 0 ||
        sigaction(SIGUSR1, &sig_action, nullptr) != 0) {
        close(sockets_[0]);
        close(sockets_[1]);
        return false;
    }

    return true;
}

SignalHandler::SignalHandler(QObject* parent) : QObject(parent),
    socket_notifier_(nullptr)
{
    socket_notifier_ = new QSocketNotifier(sockets_[1],
        QSocketNotifier::Read, this);
    connect(socket_notifier_, SIGNAL(activated(int)),
        SLOT(on_socket_notifier_activated()));
}

void SignalHandler::on_socket_notifier_activated()
{
    socket_notifier_->setEnabled(false);

    int sig_number;
    if (read(sockets_[1], &sig_number, sizeof(int)) != sizeof(int)) {
        qDebug() << "Failed to catch signal";
        abort();
    }

    switch (sig_number) {
    case SIGINT:
        Q_EMIT int_received();
        break;
    case SIGTERM:
        Q_EMIT term_received();
        break;
    case SIGUSR1:
        Q_EMIT usr1_received();
        break;
    }

    socket_notifier_->setEnabled(true);
}

void SignalHandler::handle_signals(int sig_number)
{
    if (write(sockets_[0], &sig_number, sizeof(int)) != sizeof(int)) {
        // Failed to handle signal
        abort();
    }
}