thr_sigwait.c revision 49439 
1/*
2 * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by John Birrell.
16 * 4. Neither the name of the author nor the names of any co-contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $Id: uthread_sigwait.c,v 1.6 1999/06/20 08:28:47 jb Exp $
33 */
34#include <signal.h>
35#include <errno.h>
36#ifdef _THREAD_SAFE
37#include <pthread.h>
38#include "pthread_private.h"
39
40int
41sigwait(const sigset_t * set, int *sig)
42{
43	int		ret = 0;
44	int		i;
45	sigset_t	tempset, waitset;
46	struct sigaction act;
47
48	/*
49	 * Specify the thread kernel signal handler.
50	 */
51	act.sa_handler = (void (*) ()) _thread_sig_handler;
52	act.sa_flags = SA_RESTART;
53	act.sa_mask = *set;
54
55	/* Ensure the scheduling signal is masked: */
56	sigaddset(&act.sa_mask, _SCHED_SIGNAL);
57
58	/*
59	 * Initialize the set of signals that will be waited on:
60	 */
61	waitset = *set;
62
63	/* These signals can't be waited on. */
64	sigdelset(&waitset, SIGKILL);
65	sigdelset(&waitset, SIGSTOP);
66	sigdelset(&waitset, _SCHED_SIGNAL);
67	sigdelset(&waitset, SIGCHLD);
68	sigdelset(&waitset, SIGINFO);
69
70	/* Check to see if a pending signal is in the wait mask. */
71	if (tempset = (_thread_run->sigpend & waitset)) {
72		/* Enter a loop to find a pending signal: */
73		for (i = 1; i < NSIG; i++) {
74			if (sigismember (&tempset, i))
75				break;
76		}
77
78		/* Clear the pending signal: */
79		sigdelset(&_thread_run->sigpend,i);
80
81		/* Return the signal number to the caller: */
82		*sig = i;
83
84		return (0);
85	}
86
87	/*
88	 * Enter a loop to find the signals that are SIG_DFL.  For
89	 * these signals we must install a dummy signal handler in
90	 * order for the kernel to pass them in to us.  POSIX says
91	 * that the _application_ must explicitly install a dummy
92	 * handler for signals that are SIG_IGN in order to sigwait
93	 * on them.  Note that SIG_IGN signals are left in the
94	 * mask because a subsequent sigaction could enable an
95	 * ignored signal.
96	 */
97	for (i = 1; i < NSIG; i++) {
98		if (sigismember(&waitset, i) &&
99		    (_thread_sigact[i - 1].sa_handler == SIG_DFL)) {
100			if (_thread_sys_sigaction(i,&act,NULL) != 0)
101				ret = -1;
102		}
103	}
104	if (ret == 0) {
105
106		/*
107		 * Save the wait signal mask.  The wait signal
108		 * mask is independent of the threads signal mask
109		 * and requires separate storage.
110		 */
111		_thread_run->data.sigwait = &waitset;
112
113		/* Wait for a signal: */
114		_thread_kern_sched_state(PS_SIGWAIT, __FILE__, __LINE__);
115
116		/* Return the signal number to the caller: */
117		*sig = _thread_run->signo;
118
119		/*
120		 * Probably unnecessary, but since it's in a union struct
121		 * we don't know how it could be used in the future.
122		 */
123		_thread_run->data.sigwait = NULL;
124	}
125
126	/* Restore the sigactions: */
127	act.sa_handler = SIG_DFL;
128	for (i = 1; i < NSIG; i++) {
129		if (sigismember(&waitset, i) &&
130		    (_thread_sigact[i - 1].sa_handler == SIG_DFL)) {
131			if (_thread_sys_sigaction(i,&act,NULL) != 0)
132				ret = -1;
133		}
134	}
135
136	/* Return the completion status: */
137	return (ret);
138}
139#endif
140