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raise_default_signal.c revision 1.1 
      1 /*	$NetBSD: raise_default_signal.c,v 1.1 2007/09/25 01:13:56 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 #include <sys/cdefs.h>
     40 #if defined(LIBC_SCCS) && !defined(lint)
     41 __RCSID("$NetBSD: raise_default_signal.c,v 1.1 2007/09/25 01:13:56 lukem Exp $");
     42 #endif
     43 
     44 #include <errno.h>
     45 #include <signal.h>
     46 #include <stdio.h>
     47 #include <string.h>
     48 #include <util.h>
     49 
     50 /*
     51  * raise_default_signal sig
     52  *	Raise the default signal handler for sig, by
     53  *	- block all signals
     54  *	- set the signal handler to SIG_DFL
     55  *	- raise the signal
     56  *	- unblock the signal to deliver it
     57  *
     58  *	The original signal mask and signal handler is restored on exit
     59  *	(whether successful or not).
     60  *
     61  *	Returns 0 on success, or -1 on failure with errno set to
     62  *	on of the values for sigemptyset(), sigaddset(), sigprocmask(),
     63  *	sigaction(), or raise().
     64  */
     65 int
     66 raise_default_signal(int sig)
     67 {
     68 	struct sigaction origact, act;
     69 	sigset_t origmask, fullmask, mask;
     70 	int retval, oerrno;
     71 
     72 	retval = -1;
     73 
     74 		/* Setup data structures */
     75 		/* XXX memset(3) isn't async-safe according to signal(7) */
     76 	(void)memset(&act, 0, sizeof(act));
     77 	act.sa_handler = SIG_DFL;
     78 	act.sa_flags = 0;
     79 	if ((sigemptyset(&act.sa_mask) == -1) ||
     80 	    (sigfillset(&fullmask) == -1) ||
     81 	    (sigemptyset(&mask) == -1) ||
     82 	    (sigaddset(&mask, sig) == -1))
     83 		goto restore_none;
     84 
     85 		/* Block all signals */
     86 	if (sigprocmask(SIG_BLOCK, &fullmask, &origmask) == -1)
     87 		goto restore_none;
     88 		/* (use 'goto restore_mask' to restore state) */
     89 
     90 		/* Enable the SIG_DFL handler */
     91 	if (sigaction(sig, &act, &origact) == -1)
     92 		goto restore_mask;
     93 		/* (use 'goto restore_act' to restore state) */
     94 
     95 		/* Raise the signal, and unblock the signal to deliver it */
     96 	if ((raise(sig) == -1) ||
     97 	    (sigprocmask(SIG_UNBLOCK, &mask, NULL) == -1))
     98 		goto restore_act;
     99 
    100 		/* Flag successful raise() */
    101 	retval = 0;
    102 
    103 		/* Restore the original handler */
    104  restore_act:
    105 	oerrno = errno;
    106 	(void)sigaction(sig, &origact, NULL);
    107 	errno = oerrno;
    108 
    109 		/* Restore the original mask */
    110  restore_mask:
    111 	oerrno = errno;
    112 	(void)sigprocmask(SIG_SETMASK, &origmask, NULL);
    113 	errno = oerrno;
    114 
    115  restore_none:
    116 	return retval;
    117 }
    118