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raise_default_signal.c revision 1.2 
      1 /*	$NetBSD: raise_default_signal.c,v 1.2 2007/09/28 09:07:16 lukem 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  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *        This product includes software developed by the NetBSD
     21  *        Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #if HAVE_NBTOOL_CONFIG_H
     40 #include "nbtool_config.h"
     41 #endif
     42 
     43 #include <sys/cdefs.h>
     44 #if defined(LIBC_SCCS) && !defined(lint)
     45 __RCSID("$NetBSD: raise_default_signal.c,v 1.2 2007/09/28 09:07:16 lukem Exp $");
     46 #endif
     47 
     48 #include <errno.h>
     49 #include <signal.h>
     50 #include <stdio.h>
     51 #include <string.h>
     52 #include <util.h>
     53 
     54 #if ! HAVE_RAISE_DEFAULT_SIGNAL
     55 /*
     56  * raise_default_signal sig
     57  *	Raise the default signal handler for sig, by
     58  *	- block all signals
     59  *	- set the signal handler to SIG_DFL
     60  *	- raise the signal
     61  *	- unblock the signal to deliver it
     62  *
     63  *	The original signal mask and signal handler is restored on exit
     64  *	(whether successful or not).
     65  *
     66  *	Returns 0 on success, or -1 on failure with errno set to
     67  *	on of the values for sigemptyset(), sigaddset(), sigprocmask(),
     68  *	sigaction(), or raise().
     69  */
     70 int
     71 raise_default_signal(int sig)
     72 {
     73 	struct sigaction origact, act;
     74 	sigset_t origmask, fullmask, mask;
     75 	int retval, oerrno;
     76 
     77 	retval = -1;
     78 
     79 		/* Setup data structures */
     80 		/* XXX memset(3) isn't async-safe according to signal(7) */
     81 	(void)memset(&act, 0, sizeof(act));
     82 	act.sa_handler = SIG_DFL;
     83 	act.sa_flags = 0;
     84 	if ((sigemptyset(&act.sa_mask) == -1) ||
     85 	    (sigfillset(&fullmask) == -1) ||
     86 	    (sigemptyset(&mask) == -1) ||
     87 	    (sigaddset(&mask, sig) == -1))
     88 		goto restore_none;
     89 
     90 		/* Block all signals */
     91 	if (sigprocmask(SIG_BLOCK, &fullmask, &origmask) == -1)
     92 		goto restore_none;
     93 		/* (use 'goto restore_mask' to restore state) */
     94 
     95 		/* Enable the SIG_DFL handler */
     96 	if (sigaction(sig, &act, &origact) == -1)
     97 		goto restore_mask;
     98 		/* (use 'goto restore_act' to restore state) */
     99 
    100 		/* Raise the signal, and unblock the signal to deliver it */
    101 	if ((raise(sig) == -1) ||
    102 	    (sigprocmask(SIG_UNBLOCK, &mask, NULL) == -1))
    103 		goto restore_act;
    104 
    105 		/* Flag successful raise() */
    106 	retval = 0;
    107 
    108 		/* Restore the original handler */
    109  restore_act:
    110 	oerrno = errno;
    111 	(void)sigaction(sig, &origact, NULL);
    112 	errno = oerrno;
    113 
    114 		/* Restore the original mask */
    115  restore_mask:
    116 	oerrno = errno;
    117 	(void)sigprocmask(SIG_SETMASK, &origmask, NULL);
    118 	errno = oerrno;
    119 
    120  restore_none:
    121 	return retval;
    122 }
    123 
    124 #endif	/* ! HAVE_RAISE_DEFAULT_SIGNAL */
    125