The Android Open Source Project | 2949f58 | 2009-03-03 19:30:46 -0800 | [diff] [blame] | 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 |
| 23 | static const char rcsid[] _U_ = |
JP Abgrall | 53f17a9 | 2014-02-12 14:02:41 -0800 | [diff] [blame] | 24 | "@(#) $Header: /tcpdump/master/tcpdump/setsignal.c,v 1.11 2003-11-16 09:36:42 guy Exp $ (LBL)"; |
The Android Open Source Project | 2949f58 | 2009-03-03 19:30:46 -0800 | [diff] [blame] | 25 | #endif |
| 26 | |
| 27 | #ifdef HAVE_CONFIG_H |
| 28 | #include "config.h" |
| 29 | #endif |
| 30 | |
| 31 | #include <tcpdump-stdinc.h> |
| 32 | |
| 33 | #include <signal.h> |
| 34 | #ifdef HAVE_SIGACTION |
| 35 | #include <string.h> |
| 36 | #endif |
| 37 | |
| 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, whenever possible, partial BSD |
| 46 | * semantics, i.e. the signal handler is restored following service |
| 47 | * of the signal, but system calls are *not* restarted, so that if |
| 48 | * "pcap_breakloop()" is called in a signal handler in a live capture, |
| 49 | * the read/recvfrom/whatever in the live capture doesn't get restarted, |
| 50 | * it returns -1 and sets "errno" to EINTR, so we can break out of the |
| 51 | * live capture loop. |
| 52 | * |
| 53 | * We use "sigaction()" if available. We don't specify that the signal |
| 54 | * should restart system calls, so that should always do what we want. |
| 55 | * |
| 56 | * Otherwise, if "sigset()" is available, it probably has BSD semantics |
| 57 | * while "signal()" has traditional semantics, so we use "sigset()"; it |
| 58 | * might cause system calls to be restarted for the signal, however. |
| 59 | * I don't know whether, in any systems where it did cause system calls to |
| 60 | * be restarted, there was a way to ask it not to do so; there may no |
| 61 | * longer be any interesting systems without "sigaction()", however, |
| 62 | * and, if there are, they might have "sigvec()" with SV_INTERRUPT |
| 63 | * (which I think first appeared in 4.3BSD). |
| 64 | * |
| 65 | * Otherwise, we use "signal()" - which means we might get traditional |
| 66 | * semantics, wherein system calls don't get restarted *but* the |
| 67 | * signal handler is reset to SIG_DFL and the signal is not blocked, |
| 68 | * so that a subsequent signal would kill the process immediately. |
| 69 | * |
| 70 | * Did I mention that signals suck? At least in POSIX-compliant systems |
| 71 | * they suck far less, as those systems have "sigaction()". |
| 72 | */ |
| 73 | RETSIGTYPE |
| 74 | (*setsignal (int sig, RETSIGTYPE (*func)(int)))(int) |
| 75 | { |
| 76 | #ifdef HAVE_SIGACTION |
| 77 | struct sigaction old, new; |
| 78 | |
| 79 | memset(&new, 0, sizeof(new)); |
| 80 | new.sa_handler = func; |
JP Abgrall | 53f17a9 | 2014-02-12 14:02:41 -0800 | [diff] [blame] | 81 | if (sig == SIGCHLD) |
| 82 | new.sa_flags = SA_RESTART; |
The Android Open Source Project | 2949f58 | 2009-03-03 19:30:46 -0800 | [diff] [blame] | 83 | if (sigaction(sig, &new, &old) < 0) |
| 84 | return (SIG_ERR); |
| 85 | return (old.sa_handler); |
| 86 | |
| 87 | #else |
| 88 | #ifdef HAVE_SIGSET |
| 89 | return (sigset(sig, func)); |
| 90 | #else |
| 91 | return (signal(sig, func)); |
| 92 | #endif |
| 93 | #endif |
| 94 | } |
| 95 | |