lib/libutil/raise_default_signal.c

   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  *
  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 1.2 2007/09/28 09:07:16 lukem 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  */
  63 int
  64 raise_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 */