setsignal.c revision 39297 
1/*
2 * Copyright (c) 1997
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution, and (3) all advertising materials mentioning
11 * features or use of this software display the following acknowledgement:
12 * ``This product includes software developed by the University of California,
13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14 * the University nor the names of its contributors may be used to endorse
15 * or promote products derived from this software without specific prior
16 * written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 */
21
22#ifndef lint
23static const char rcsid[] =
24    "@(#) $Header: setsignal.c,v 1.4 97/06/15 13:20:29 leres Exp $ (LBL)";
25#endif
26
27#include <sys/types.h>
28
29#ifdef HAVE_MEMORY_H
30#include <memory.h>
31#endif
32#include <signal.h>
33#ifdef HAVE_SIGACTION
34#include <string.h>
35#endif
36
37#include "gnuc.h"
38#ifdef HAVE_OS_PROTO_H
39#include "os-proto.h"
40#endif
41
42#include "setsignal.h"
43
44/*
45 * An os independent signal() with BSD semantics, e.g. the signal
46 * catcher is restored following service of the signal.
47 *
48 * When sigset() is available, signal() has SYSV semantics and sigset()
49 * has BSD semantics and call interface. Unfortunately, Linux does not
50 * have sigset() so we use the more complicated sigaction() interface
51 * there.
52 *
53 * Did I mention that signals suck?
54 */
55RETSIGTYPE
56(*setsignal (int sig, RETSIGTYPE (*func)(int)))(int)
57{
58#ifdef HAVE_SIGACTION
59	struct sigaction old, new;
60
61	memset(&new, 0, sizeof(new));
62	new.sa_handler = func;
63#ifdef SA_RESTART
64	new.sa_flags |= SA_RESTART;
65#endif
66	if (sigaction(sig, &new, &old) < 0)
67		return (SIG_ERR);
68	return (old.sa_handler);
69
70#else
71#ifdef HAVE_SIGSET
72	return (sigset(sig, func));
73#else
74	return (signal(sig, func));
75#endif
76#endif
77}
78
79