| /* |
| * Copyright (c) 1997 |
| * The Regents of the University of California. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that: (1) source code distributions |
| * retain the above copyright notice and this paragraph in its entirety, (2) |
| * distributions including binary code include the above copyright notice and |
| * this paragraph in its entirety in the documentation or other materials |
| * provided with the distribution, and (3) all advertising materials mentioning |
| * features or use of this software display the following acknowledgement: |
| * ``This product includes software developed by the University of California, |
| * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of |
| * the University nor the names of its contributors may be used to endorse |
| * or promote products derived from this software without specific prior |
| * written permission. |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED |
| * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
| */ |
| |
| #ifndef lint |
| static const char rcsid[] _U_ = |
| "@(#) $Header: /tcpdump/master/tcpdump/setsignal.c,v 1.11 2003-11-16 09:36:42 guy Exp $ (LBL)"; |
| #endif |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #include <tcpdump-stdinc.h> |
| |
| #include <signal.h> |
| #ifdef HAVE_SIGACTION |
| #include <string.h> |
| #endif |
| |
| #ifdef HAVE_OS_PROTO_H |
| #include "os-proto.h" |
| #endif |
| |
| #include "setsignal.h" |
| |
| /* |
| * An OS-independent signal() with, whenever possible, partial BSD |
| * semantics, i.e. the signal handler is restored following service |
| * of the signal, but system calls are *not* restarted, so that if |
| * "pcap_breakloop()" is called in a signal handler in a live capture, |
| * the read/recvfrom/whatever in the live capture doesn't get restarted, |
| * it returns -1 and sets "errno" to EINTR, so we can break out of the |
| * live capture loop. |
| * |
| * We use "sigaction()" if available. We don't specify that the signal |
| * should restart system calls, so that should always do what we want. |
| * |
| * Otherwise, if "sigset()" is available, it probably has BSD semantics |
| * while "signal()" has traditional semantics, so we use "sigset()"; it |
| * might cause system calls to be restarted for the signal, however. |
| * I don't know whether, in any systems where it did cause system calls to |
| * be restarted, there was a way to ask it not to do so; there may no |
| * longer be any interesting systems without "sigaction()", however, |
| * and, if there are, they might have "sigvec()" with SV_INTERRUPT |
| * (which I think first appeared in 4.3BSD). |
| * |
| * Otherwise, we use "signal()" - which means we might get traditional |
| * semantics, wherein system calls don't get restarted *but* the |
| * signal handler is reset to SIG_DFL and the signal is not blocked, |
| * so that a subsequent signal would kill the process immediately. |
| * |
| * Did I mention that signals suck? At least in POSIX-compliant systems |
| * they suck far less, as those systems have "sigaction()". |
| */ |
| RETSIGTYPE |
| (*setsignal (int sig, RETSIGTYPE (*func)(int)))(int) |
| { |
| #ifdef HAVE_SIGACTION |
| struct sigaction old, new; |
| |
| memset(&new, 0, sizeof(new)); |
| new.sa_handler = func; |
| if (sigaction(sig, &new, &old) < 0) |
| return (SIG_ERR); |
| return (old.sa_handler); |
| |
| #else |
| #ifdef HAVE_SIGSET |
| return (sigset(sig, func)); |
| #else |
| return (signal(sig, func)); |
| #endif |
| #endif |
| } |
| |