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      1 /*	$NetBSD: sigset.c,v 1.2 2008/04/28 20:22:59 martin Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2003 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Klaus Klein.
      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 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 __RCSID("$NetBSD: sigset.c,v 1.2 2008/04/28 20:22:59 martin Exp $");
     35 #endif
     36 
     37 #include "namespace.h"
     38 #include <errno.h>
     39 #include <signal.h>
     40 #include <stddef.h>
     41 
     42 sig_t
     43 sigset(int sig, void (*disp)(int))
     44 {
     45 	sigset_t set, oset;
     46 	struct sigaction sa, osa;
     47 
     48 	osa.sa_handler = SIG_ERR;
     49 
     50 	if (disp == SIG_HOLD) {
     51 		/* Add sig to current signal mask. */
     52 		if (sigemptyset(&set) != 0)
     53 			goto out;
     54 		if (sigaddset(&set, sig) != 0)
     55 			goto out;
     56 		if (sigprocmask(SIG_BLOCK, &set, &oset) != 0)
     57 			goto out;
     58 
     59 		if (sigismember(&oset, sig)) {
     60 			/* Had been masked before, return SIG_HOLD. */
     61 			osa.sa_handler = SIG_HOLD;
     62 		} else {
     63 			/* Return previous disposition. */
     64 		 	(void)sigaction(sig, NULL, &osa);
     65 		}
     66 	} else if (disp == SIG_ERR) {
     67 		errno = EINVAL;
     68 	} else {
     69 		/* Set up and install new disposition. */
     70 		sa.sa_handler = disp;
     71 		if (sigemptyset(&sa.sa_mask) != 0)
     72 			goto out;
     73 		sa.sa_flags = 0;
     74 
     75 		if (sigaction(sig, &sa, &osa) != 0) {
     76 			osa.sa_handler = SIG_ERR;
     77 			goto out;
     78 		}
     79 
     80 		/* Delete sig from current signal mask. */
     81 		if (sigemptyset(&set) != 0)
     82 			return (SIG_ERR);
     83 		if (sigaddset(&set, sig) != 0)
     84 			return (SIG_ERR);
     85 		if (sigprocmask(SIG_UNBLOCK, &set, &oset) != 0)
     86 			return (SIG_ERR);
     87 
     88 		/* If had been masked before, return SIG_HOLD. */
     89 		if (sigismember(&oset, sig))
     90 			osa.sa_handler = SIG_HOLD;
     91 	}
     92 
     93  out:
     94 	return (osa.sa_handler);
     95 }
     96