48 lines
1.7 KiB
C
48 lines
1.7 KiB
C
/*
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* Copyright (c) 2013, 2014 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* signal/signal.c
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* Configure and retrieve a signal handler.
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*/
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#include <signal.h>
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#include <string.h>
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void (*signal(int signum, void (*handler)(int)))(int)
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{
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// Create a structure describing the new handler.
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struct sigaction newact;
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memset(&newact, 0, sizeof(newact));
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sigemptyset(&newact.sa_mask);
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newact.sa_handler = handler;
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newact.sa_flags = SA_RESTART;
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// Register the new handler and atomically get the old.
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struct sigaction oldact;
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if ( sigaction(signum, &newact, &oldact) != 0 )
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return SIG_ERR;
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// We can't return the old handler properly if it's SA_SIGINFO or SA_COOKIE,
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// unless it's the common SIG_IGN or SIG_DFL handlers. Let's just say to the
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// caller that it's SIG_DFL and assume that they'll be using sigaction
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// instead if they wish to restore an old handler.
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if ( (oldact.sa_flags & (SA_SIGINFO | SA_COOKIE)) &&
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oldact.sa_handler != SIG_IGN &&
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oldact.sa_handler != SIG_DFL )
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return SIG_DFL;
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return oldact.sa_handler;
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}
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