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