1/*	$NetBSD: raise_default_signal.c,v 1.3 2008/04/28 20:23:03 martin Exp $	 */
2
3/*-
4 * Copyright (c) 2007 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Luke Mewburn.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#if HAVE_NBTOOL_CONFIG_H
33#include "nbtool_config.h"
34#endif
35
36#include <sys/cdefs.h>
37#if defined(LIBC_SCCS) && !defined(lint)
38__RCSID("$NetBSD: raise_default_signal.c,v 1.3 2008/04/28 20:23:03 martin Exp $");
39#endif
40
41#include <errno.h>
42#include <signal.h>
43#include <stdio.h>
44#include <string.h>
45#include <util.h>
46
47#if ! HAVE_RAISE_DEFAULT_SIGNAL
48/*
49 * raise_default_signal sig
50 *	Raise the default signal handler for sig, by
51 *	- block all signals
52 *	- set the signal handler to SIG_DFL
53 *	- raise the signal
54 *	- unblock the signal to deliver it
55 *
56 *	The original signal mask and signal handler is restored on exit
57 *	(whether successful or not).
58 *
59 *	Returns 0 on success, or -1 on failure with errno set to
60 *	on of the values for sigemptyset(), sigaddset(), sigprocmask(),
61 *	sigaction(), or raise().
62 */
63int
64raise_default_signal(int sig)
65{
66	struct sigaction origact, act;
67	sigset_t origmask, fullmask, mask;
68	int retval, oerrno;
69
70	retval = -1;
71
72		/* Setup data structures */
73		/* XXX memset(3) isn't async-safe according to signal(7) */
74	(void)memset(&act, 0, sizeof(act));
75	act.sa_handler = SIG_DFL;
76	act.sa_flags = 0;
77	if ((sigemptyset(&act.sa_mask) == -1) ||
78	    (sigfillset(&fullmask) == -1) ||
79	    (sigemptyset(&mask) == -1) ||
80	    (sigaddset(&mask, sig) == -1))
81		goto restore_none;
82
83		/* Block all signals */
84	if (sigprocmask(SIG_BLOCK, &fullmask, &origmask) == -1)
85		goto restore_none;
86		/* (use 'goto restore_mask' to restore state) */
87
88		/* Enable the SIG_DFL handler */
89	if (sigaction(sig, &act, &origact) == -1)
90		goto restore_mask;
91		/* (use 'goto restore_act' to restore state) */
92
93		/* Raise the signal, and unblock the signal to deliver it */
94	if ((raise(sig) == -1) ||
95	    (sigprocmask(SIG_UNBLOCK, &mask, NULL) == -1))
96		goto restore_act;
97
98		/* Flag successful raise() */
99	retval = 0;
100
101		/* Restore the original handler */
102 restore_act:
103	oerrno = errno;
104	(void)sigaction(sig, &origact, NULL);
105	errno = oerrno;
106
107		/* Restore the original mask */
108 restore_mask:
109	oerrno = errno;
110	(void)sigprocmask(SIG_SETMASK, &origmask, NULL);
111	errno = oerrno;
112
113 restore_none:
114	return retval;
115}
116
117#endif	/* ! HAVE_RAISE_DEFAULT_SIGNAL */
118