1 /* $OpenBSD: uthread_sigwait.c,v 1.13 2003/01/31 04:46:17 marc Exp $ */
2 /*
3 * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. All advertising materials mentioning features or use of this software
15 * must display the following acknowledgement:
16 * This product includes software developed by John Birrell.
17 * 4. Neither the name of the author nor the names of any co-contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * $FreeBSD: uthread_sigwait.c,v 1.10 1999/09/30 14:51:31 marcel Exp $
34 */
35 #include <signal.h>
36 #include <errno.h>
37 #ifdef _THREAD_SAFE
38 #include <pthread.h>
39 #include "pthread_private.h"
40
41 int
sigwait(const sigset_t * set,int * sig)42 sigwait(const sigset_t * set, int *sig)
43 {
44 struct pthread *curthread = _get_curthread();
45 int ret = 0;
46 int i;
47 sigset_t tempset, waitset;
48 struct sigaction act;
49
50 _thread_enter_cancellation_point();
51
52 /*
53 * Specify the thread kernel signal handler.
54 */
55 act.sa_handler = (void (*) (int)) _thread_sig_handler;
56 act.sa_flags = SA_SIGINFO | SA_RESTART;
57
58 /* Ensure the signal handler cannot be interrupted by other signals: */
59 sigfillset(&act.sa_mask);
60
61 /*
62 * Initialize the set of signals that will be waited on:
63 */
64 waitset = *set;
65
66 /* These signals can't be waited on. */
67 sigdelset(&waitset, SIGKILL);
68 sigdelset(&waitset, SIGSTOP);
69 sigdelset(&waitset, _SCHED_SIGNAL);
70 sigdelset(&waitset, SIGCHLD);
71 sigdelset(&waitset, SIGINFO);
72
73 /* Check to see if a pending signal is in the wait mask. */
74 tempset = curthread->sigpend;
75 tempset |= _process_sigpending;
76 tempset &= waitset;
77 if (tempset != 0) {
78 /* Enter a loop to find a pending signal: */
79 for (i = 1; i < NSIG; i++) {
80 if (sigismember(&tempset, i))
81 break;
82 }
83
84 /* Clear the pending signal: */
85 _thread_clear_pending(i, curthread);
86
87 /* Return the signal number to the caller: */
88 *sig = i;
89
90 _thread_leave_cancellation_point();
91 return (0);
92 }
93
94 /*
95 * Access the _thread_dfl_count array under the protection of signal
96 * deferral.
97 */
98 _thread_kern_sig_defer();
99
100 /*
101 * Enter a loop to find the signals that are SIG_DFL. For
102 * these signals we must install a dummy signal handler in
103 * order for the kernel to pass them in to us. POSIX says
104 * that the _application_ must explicitly install a dummy
105 * handler for signals that are SIG_IGN in order to sigwait
106 * on them. Note that SIG_IGN signals are left in the
107 * mask because a subsequent sigaction could enable an
108 * ignored signal.
109 */
110 sigemptyset(&tempset);
111 for (i = 1; i < NSIG; i++) {
112 if (sigismember(&waitset, i) &&
113 (_thread_sigact[i - 1].sa_handler == SIG_DFL)) {
114 _thread_dfl_count[i]++;
115 sigaddset(&tempset, i);
116 if (_thread_dfl_count[i] == 1) {
117 if (_thread_sys_sigaction(i, &act, NULL) != 0)
118 ret = -1;
119 }
120 }
121 }
122
123 /* Done accessing _thread_dfl_count for now. */
124 _thread_kern_sig_undefer();
125
126 if (ret == 0) {
127 /*
128 * Save the wait signal mask. The wait signal
129 * mask is independent of the threads signal mask
130 * and requires separate storage.
131 */
132 curthread->data.sigwait = &waitset;
133
134 /* Wait for a signal: */
135 _thread_kern_sched_state(PS_SIGWAIT, __FILE__, __LINE__);
136
137 /* Return the signal number to the caller: */
138 *sig = curthread->signo;
139
140 /*
141 * Probably unnecessary, but since it's in a union struct
142 * we don't know how it could be used in the future.
143 */
144 curthread->data.sigwait = NULL;
145 }
146
147 /*
148 * Access the _thread_dfl_count array under the protection of signal
149 * deferral.
150 */
151 _thread_kern_sig_defer();
152
153 /* Restore the sigactions: */
154 act.sa_handler = SIG_DFL;
155 for (i = 1; i < NSIG; i++) {
156 if (sigismember(&tempset, i)) {
157 _thread_dfl_count[i]--;
158 if ((_thread_sigact[i - 1].sa_handler == SIG_DFL) &&
159 (_thread_dfl_count[i] == 0)) {
160 if (_thread_sys_sigaction(i, &act, NULL) != 0)
161 ret = -1;
162 }
163 }
164 }
165
166 /* Done accessing _thread_dfl_count. */
167 _thread_kern_sig_undefer();
168
169 _thread_leave_cancellation_point();
170
171 /* Return the completion status: */
172 return (ret);
173 }
174 #endif
175