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Diffstat (limited to 'src/event/SignalMonitor.cxx')
| -rw-r--r-- | src/event/SignalMonitor.cxx | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/src/event/SignalMonitor.cxx b/src/event/SignalMonitor.cxx new file mode 100644 index 000000000..ee72dea72 --- /dev/null +++ b/src/event/SignalMonitor.cxx @@ -0,0 +1,204 @@ +/* + * Copyright (C) 2003-2013 The Music Player Daemon Project + * http://www.musicpd.org + * + * 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. + */ + +#include "config.h" +#include "SignalMonitor.hxx" + +#ifndef WIN32 + +#include "WakeFD.hxx" +#include "SocketMonitor.hxx" +#include "util/Manual.hxx" +#include "system/FatalError.hxx" + +#ifdef USE_SIGNALFD +#include "system/SignalFD.hxx" +#else +#include "WakeFD.hxx" +#endif + +#ifndef USE_SIGNALFD +#include <atomic> +#endif + +#include <algorithm> + +class SignalMonitor final : private SocketMonitor { +#ifdef USE_SIGNALFD + SignalFD fd; +#else + WakeFD fd; +#endif + +public: + SignalMonitor(EventLoop &_loop) + :SocketMonitor(_loop) { +#ifndef USE_SIGNALFD + SocketMonitor::Open(fd.Get()); + SocketMonitor::ScheduleRead(); +#endif + } + + ~SignalMonitor() { + /* prevent the descriptor to be closed twice */ +#ifdef USE_SIGNALFD + if (SocketMonitor::IsDefined()) +#endif + SocketMonitor::Steal(); + } + +#ifdef USE_SIGNALFD + void Update(sigset_t &mask) { + const bool was_open = SocketMonitor::IsDefined(); + + fd.Create(mask); + + if (!was_open) { + SocketMonitor::Open(fd.Get()); + SocketMonitor::ScheduleRead(); + } + } +#else + void WakeUp() { + fd.Write(); + } +#endif + +private: + virtual bool OnSocketReady(unsigned flags) override; +}; + +/* this should be enough - is it? */ +static constexpr unsigned MAX_SIGNAL = 64; + +static SignalHandler signal_handlers[MAX_SIGNAL]; + +#ifdef USE_SIGNALFD +static sigset_t signal_mask; +#else +static std::atomic_bool signal_pending[MAX_SIGNAL]; +#endif + +static Manual<SignalMonitor> monitor; + +#ifndef USE_SIGNALFD +static void +SignalCallback(int signo) +{ + assert(signal_handlers[signo] != nullptr); + + if (!signal_pending[signo].exchange(true)) + monitor->WakeUp(); +} +#endif + +void +SignalMonitorInit(EventLoop &loop) +{ +#ifdef USE_SIGNALFD + sigemptyset(&signal_mask); +#endif + + monitor.Construct(loop); +} + +#ifndef USE_SIGNALFD + +static void +x_sigaction(int signum, const struct sigaction &act) +{ + if (sigaction(signum, &act, nullptr) < 0) + FatalSystemError("sigaction() failed"); +} + +#endif + +void +SignalMonitorFinish() +{ +#ifdef USE_SIGNALFD + std::fill_n(signal_handlers, MAX_SIGNAL, nullptr); +#else + struct sigaction sa; + sa.sa_flags = 0; + sigemptyset(&sa.sa_mask); + sa.sa_handler = SIG_DFL; + + for (unsigned i = 0; i < MAX_SIGNAL; ++i) { + if (signal_handlers[i] != nullptr) { + x_sigaction(i, sa); + signal_handlers[i] = nullptr; + } + } + + std::fill_n(signal_pending, MAX_SIGNAL, false); +#endif + + monitor.Destruct(); +} + +void +SignalMonitorRegister(int signo, SignalHandler handler) +{ + assert(signal_handlers[signo] == nullptr); +#ifndef USE_SIGNALFD + assert(!signal_pending[signo]); +#endif + + signal_handlers[signo] = handler; + +#ifdef USE_SIGNALFD + sigaddset(&signal_mask, signo); + + if (sigprocmask(SIG_BLOCK, &signal_mask, nullptr) < 0) + FatalSystemError("sigprocmask() failed"); + + monitor->Update(signal_mask); +#else + struct sigaction sa; + sa.sa_flags = 0; + sigemptyset(&sa.sa_mask); + sa.sa_handler = SignalCallback; + x_sigaction(signo, sa); +#endif +} + +bool +SignalMonitor::OnSocketReady(unsigned) +{ +#ifdef USE_SIGNALFD + int signo; + while ((signo = fd.Read()) >= 0) { + assert(unsigned(signo) < MAX_SIGNAL); + assert(signal_handlers[signo] != nullptr); + + signal_handlers[signo](); + } +#else + fd.Read(); + + for (unsigned i = 0; i < MAX_SIGNAL; ++i) + if (signal_pending[i].exchange(false)) + signal_handlers[i](); +#endif + + return true; +} + +#endif |