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
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
/*
* Copyright (C) 2003-2015 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>
#ifdef USE_SIGNALFD
#include <pthread.h>
#endif
#include <assert.h>
#include <signal.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
}
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;
#ifdef USE_SIGNALFD
/**
* This is a pthread_atfork() callback that unblocks the signals that
* were blocked for our signalfd(). Without this, our child processes
* would inherit the blocked signals.
*/
static void
at_fork_child()
{
sigprocmask(SIG_UNBLOCK, &signal_mask, nullptr);
}
#else
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);
pthread_atfork(nullptr, nullptr, at_fork_child);
#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
|
