aboutsummaryrefslogtreecommitdiffstats
path: root/src/event/SignalMonitor.cxx
blob: 0d96fb138473adc8469ac347b9757bca7b702486 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
/*
 * 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>

#include <assert.h>

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();
	}

	using SocketMonitor::GetEventLoop;

#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();
}

EventLoop &
SignalMonitorGetEventLoop()
{
	return monitor->GetEventLoop();
}

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