signalhandler.cpp

   1 /*
   2  * This file is part of the PulseView project.
   3  *
   4  * Copyright (C) 2013 Adam Reichold
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "signalhandler.hpp"
  21
  22 #include <cassert>
  23 #include <csignal>
  24 #include <cstdlib>
  25
  26 #include <sys/socket.h>
  27 #include <unistd.h>
  28
  29 #include <QDebug>
  30 #include <QSocketNotifier>
  31
  32 int SignalHandler::sockets_[2];
  33
  34 bool SignalHandler::prepare_signals()
  35 {
  36         if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets_) != 0)
  37                 return false;
  38
  39         struct sigaction sig_action;
  40
  41         sig_action.sa_handler = SignalHandler::handle_signals;
  42         sigemptyset(&sig_action.sa_mask);
  43         sig_action.sa_flags = SA_RESTART;
  44
  45         if (sigaction(SIGINT, &sig_action, nullptr) != 0 ||
  46                 sigaction(SIGTERM, &sig_action, nullptr) != 0 ||
  47                 sigaction(SIGUSR1, &sig_action, nullptr) != 0) {
  48                 close(sockets_[0]);
  49                 close(sockets_[1]);
  50                 return false;
  51         }
  52
  53         return true;
  54 }
  55
  56 SignalHandler::SignalHandler(QObject* parent) : QObject(parent),
  57         socket_notifier_(nullptr)
  58 {
  59         socket_notifier_ = new QSocketNotifier(sockets_[1],
  60                 QSocketNotifier::Read, this);
  61         connect(socket_notifier_, SIGNAL(activated(int)),
  62                 SLOT(on_socket_notifier_activated()));
  63 }
  64
  65 void SignalHandler::on_socket_notifier_activated()
  66 {
  67         socket_notifier_->setEnabled(false);
  68
  69         int sig_number;
  70         if (read(sockets_[1], &sig_number, sizeof(int)) != sizeof(int)) {
  71                 qDebug() << "Failed to catch signal";
  72                 abort();
  73         }
  74
  75         switch (sig_number) {
  76         case SIGINT:
  77                 Q_EMIT int_received();
  78                 break;
  79         case SIGTERM:
  80                 Q_EMIT term_received();
  81                 break;
  82         case SIGUSR1:
  83                 Q_EMIT usr1_received();
  84                 break;
  85         }
  86
  87         socket_notifier_->setEnabled(true);
  88 }
  89
  90 void SignalHandler::handle_signals(int sig_number)
  91 {
  92         if (write(sockets_[0], &sig_number, sizeof(int)) != sizeof(int)) {
  93                 // Failed to handle signal
  94                 abort();
  95         }
  96 }