lib/libc/gen/sigset.c

   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 }