mirror of
https://github.com/qTox/qTox.git
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134 lines
4.2 KiB
C++
134 lines
4.2 KiB
C++
/*
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Copyright © 2017-2018 by The qTox Project Contributors
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This file is part of qTox, a Qt-based graphical interface for Tox.
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qTox is libre software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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qTox is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with qTox. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "posixsignalnotifier.h"
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#include <QDebug>
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#include <QSocketNotifier>
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#include <array>
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#include <atomic>
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#include <errno.h>
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#include <signal.h> // sigaction()
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#include <sys/socket.h> // socketpair()
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#include <sys/types.h> // may be needed for BSD
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#include <unistd.h> // close()
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/**
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* @class PosixSignalNotifier
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* @brief Class for converting POSIX signals to Qt signals
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*/
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namespace detail {
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static std::atomic_flag g_signalSocketUsageFlag = ATOMIC_FLAG_INIT;
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static std::array<int, 2> g_signalSocketPair;
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static void signalHandler(int signum)
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{
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// DO NOT call any Qt functions directly, only limited amount of so-called async-signal-safe
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// functions can be called in signal handlers.
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// See https://doc.qt.io/qt-4.8/unix-signals.html
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// If test_and_set() returns true, it means it was already in use (only by ~PosixSignalNotifier()),
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// so we bail out. Our signal handler is blocking, only one will be called (no race between
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// threads), hence simple implementation.
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if (g_signalSocketUsageFlag.test_and_set())
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return;
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if(::write(g_signalSocketPair[0], &signum, sizeof(signum)) == -1) {
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// We hardly can do anything more usefull in signal handler, and
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// any ways it's probably very unexpected error (out of memory?),
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// since we check socket existance with a flag beforehand.
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abort();
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}
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g_signalSocketUsageFlag.clear();
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}
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} // namespace detail
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PosixSignalNotifier::~PosixSignalNotifier()
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{
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while (detail::g_signalSocketUsageFlag.test_and_set()) {
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// spin-loop until we aquire flag (signal handler might be running and have flag in use)
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}
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// do not leak sockets
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::close(detail::g_signalSocketPair[0]);
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::close(detail::g_signalSocketPair[1]);
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// do not clear the usage flag here, signal handler cannot use socket any more!
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}
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void PosixSignalNotifier::watchSignal(int signum)
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{
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sigset_t blockMask;
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sigemptyset(&blockMask); // do not prefix with ::, it's a macro on macOS
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sigaddset(&blockMask, signum); // do not prefix with ::, it's a macro on macOS
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struct sigaction action = {}; // all zeroes by default
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action.sa_handler = detail::signalHandler;
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action.sa_mask = blockMask; // allow old signal to finish before new is raised
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if (::sigaction(signum, &action, nullptr)) {
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qFatal("Failed to setup signal %d, error = %d", signum, errno);
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}
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}
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void PosixSignalNotifier::watchSignals(std::initializer_list<int> signalSet)
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{
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for (auto s: signalSet) {
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watchSignal(s);
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}
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}
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void PosixSignalNotifier::watchCommonTerminatingSignals()
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{
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watchSignals({SIGHUP, SIGINT, SIGQUIT, SIGTERM});
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}
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PosixSignalNotifier& PosixSignalNotifier::globalInstance()
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{
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static PosixSignalNotifier instance;
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return instance;
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}
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void PosixSignalNotifier::onSignalReceived()
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{
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int signum{0};
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if (::read(detail::g_signalSocketPair[1], &signum, sizeof(signum)) == -1) {
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qFatal("Failed to read from signal socket, error = %d", errno);
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}
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qDebug() << "Signal" << signum << "received";
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emit activated(signum);
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}
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PosixSignalNotifier::PosixSignalNotifier()
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{
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if (::socketpair(AF_UNIX, SOCK_STREAM, 0, detail::g_signalSocketPair.data())) {
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qFatal("Failed to create socket pair, error = %d", errno);
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}
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notifier = new QSocketNotifier(detail::g_signalSocketPair[1], QSocketNotifier::Read, this);
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connect(notifier, &QSocketNotifier::activated, this, &PosixSignalNotifier::onSignalReceived);
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}
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