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
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
|
/*
* Copyright (c) 1998 Daniel M. Eischen <eischen@vigrid.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Daniel M. Eischen.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY DANIEL M. EISCHEN AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#if defined(__FreeBSD__)
#include <pthread_np.h>
#endif
static int sigcounts[NSIG + 1];
static int sigfifo[NSIG + 1];
static int fifo_depth = 0;
static sigset_t suspender_mask;
static pthread_t suspender_tid;
static void *
sigsuspender (void *arg)
{
int save_count, status, i;
sigset_t run_mask;
/* Run with all signals blocked. */
sigfillset (&run_mask);
sigprocmask (SIG_SETMASK, &run_mask, NULL);
/* Allow these signals to wake us up during a sigsuspend. */
sigfillset (&suspender_mask); /* Default action */
sigdelset (&suspender_mask, SIGINT); /* terminate */
sigdelset (&suspender_mask, SIGHUP); /* terminate */
sigdelset (&suspender_mask, SIGQUIT); /* create core image */
sigdelset (&suspender_mask, SIGURG); /* ignore */
sigdelset (&suspender_mask, SIGIO); /* ignore */
sigdelset (&suspender_mask, SIGUSR2); /* terminate */
while (sigcounts[SIGINT] == 0) {
save_count = sigcounts[SIGUSR2];
status = sigsuspend (&suspender_mask);
if ((status == 0) || (errno != EINTR)) {
printf ("Unable to suspend for signals, "
"errno %d, return value %d\n",
errno, status);
exit (1);
}
for (i = 0; i < fifo_depth; i++)
printf ("Sigsuspend woke up by signal %d\n",
sigfifo[i]);
fifo_depth = 0;
}
pthread_exit (arg);
return (NULL);
}
static void
sighandler (int signo)
{
sigset_t set;
pthread_t self;
if ((signo >= 0) && (signo <= NSIG))
sigcounts[signo]++;
/*
* If we are running on behalf of the suspender thread,
* ensure that we have the correct mask set.
*/
self = pthread_self ();
if (self == suspender_tid) {
sigfifo[fifo_depth] = signo;
fifo_depth++;
printf (" -> Suspender thread signal handler caught signal %d\n",
signo);
sigprocmask (SIG_SETMASK, NULL, &set);
if (set != suspender_mask)
printf (" >>> FAIL: sigsuspender signal handler running "
"with incorrect mask.\n");
}
else
printf (" -> Main thread signal handler caught signal %d\n",
signo);
}
static void
send_thread_signal (pthread_t tid, int signo)
{
if (pthread_kill (tid, signo) != 0) {
printf ("Unable to send thread signal, errno %d.\n", errno);
exit (1);
}
}
static void
send_process_signal (int signo)
{
if (kill (getpid (), signo) != 0) {
printf ("Unable to send process signal, errno %d.\n", errno);
exit (1);
}
}
int main (int argc, char *argv[])
{
pthread_attr_t pattr;
void * exit_status;
struct sigaction act;
sigset_t oldset;
sigset_t newset;
/* Initialize our signal counts. */
memset ((void *) sigcounts, 0, NSIG * sizeof (int));
/* Ignore signal SIGIO. */
sigemptyset (&act.sa_mask);
sigaddset (&act.sa_mask, SIGIO);
act.sa_handler = SIG_IGN;
act.sa_flags = 0;
sigaction (SIGIO, &act, NULL);
/* Install a signal handler for SIGURG. */
sigemptyset (&act.sa_mask);
sigaddset (&act.sa_mask, SIGURG);
act.sa_handler = sighandler;
act.sa_flags = SA_RESTART;
sigaction (SIGURG, &act, NULL);
/* Install a signal handler for SIGXCPU */
sigemptyset (&act.sa_mask);
sigaddset (&act.sa_mask, SIGXCPU);
sigaction (SIGXCPU, &act, NULL);
/* Get our current signal mask. */
sigprocmask (SIG_SETMASK, NULL, &oldset);
/* Mask out SIGUSR1 and SIGUSR2. */
newset = oldset;
sigaddset (&newset, SIGUSR1);
sigaddset (&newset, SIGUSR2);
sigprocmask (SIG_SETMASK, &newset, NULL);
/* Install a signal handler for SIGUSR1 and SIGUSR2 */
sigemptyset (&act.sa_mask);
sigaddset (&act.sa_mask, SIGUSR1);
sigaddset (&act.sa_mask, SIGUSR2);
act.sa_handler = sighandler;
act.sa_flags = SA_RESTART;
sigaction (SIGUSR1, &act, NULL);
sigaction (SIGUSR2, &act, NULL);
/*
* Initialize the thread attribute.
*/
if ((pthread_attr_init (&pattr) != 0) ||
(pthread_attr_setdetachstate (&pattr,
PTHREAD_CREATE_JOINABLE) != 0)) {
printf ("Unable to initialize thread attributes.\n");
exit (1);
}
/*
* Create the sigsuspender thread.
*/
if (pthread_create (&suspender_tid, &pattr, sigsuspender, NULL) != 0) {
printf ("Unable to create thread, errno %d.\n", errno);
exit (1);
}
#if defined(__FreeBSD__)
pthread_set_name_np (suspender_tid, "sigsuspender");
#endif
/*
* Verify that an ignored signal doesn't cause a wakeup.
* We don't have a handler installed for SIGIO.
*/
send_thread_signal (suspender_tid, SIGIO);
sleep (1);
send_process_signal (SIGIO);
sleep (1);
if (sigcounts[SIGIO] != 0)
printf ("FAIL: sigsuspend wakes up for ignored signal "
"SIGIO.\n");
/*
* Verify that a signal with a default action of ignore, for
* which we have a signal handler installed, will release a
* sigsuspend.
*/
send_thread_signal (suspender_tid, SIGURG);
sleep (1);
send_process_signal (SIGURG);
sleep (1);
if (sigcounts[SIGURG] != 3)
printf ("FAIL: sigsuspend doesn't wake up for SIGURG.\n");
/*
* Verify that a SIGUSR2 signal will release a sigsuspended
* thread.
*/
send_thread_signal (suspender_tid, SIGUSR2);
sleep (1);
send_process_signal (SIGUSR2);
sleep (1);
if (sigcounts[SIGUSR2] != 2)
printf ("FAIL: sigsuspend doesn't wake up for SIGUSR2.\n");
/*
* Verify that a signal, blocked in both the main and
* sigsuspender threads, does not cause the signal handler
* to be called.
*/
send_thread_signal (suspender_tid, SIGUSR1);
sleep (1);
send_process_signal (SIGUSR1);
sleep (1);
if (sigcounts[SIGUSR1] != 0)
printf ("FAIL: signal hander called for SIGUSR1.\n");
/*
* Verify that we can still kill the process for a signal
* not being waited on by sigwait.
*/
send_process_signal (SIGPIPE);
printf ("FAIL: SIGPIPE did not terminate process.\n");
/*
* Wait for the thread to finish.
*/
pthread_join (suspender_tid, &exit_status);
return (0);
}
|