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* dhcpcd - DHCP client daemon
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* Copyright (c) 2006-2009 Roy Marples <roy@marples.name>
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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#include <sys/types.h>
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#include <sys/socket.h>
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static int signal_pipe[2];
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static const int handle_sigs[] = {
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signal_handler(int sig)
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if (write(signal_pipe[1], &sig, sizeof(sig)) != sizeof(sig))
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syslog(LOG_ERR, "failed to write signal %d: %m", sig);
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/* Read a signal from the signal pipe. Returns 0 if there is
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* no signal, -1 on error (and sets errno appropriately), and
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* your signal on success */
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memset(buf, 0, sizeof(buf));
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bytes = read(signal_pipe[0], buf, sizeof(buf));
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if (bytes >= 0 && (size_t)bytes >= sizeof(sig))
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memcpy(&sig, buf, sizeof(sig));
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/* Call this before doing anything else. Sets up the socket pair
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* and installs the signal handler */
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if (pipe(signal_pipe) == -1)
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/* Don't block on read */
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if (set_nonblock(signal_pipe[0]) == -1)
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/* Stop any scripts from inheriting us */
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if (set_cloexec(signal_pipe[0]) == -1)
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if (set_cloexec(signal_pipe[1]) == -1)
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return signal_pipe[0];
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signal_handle(void (*func)(int))
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memset(&sa, 0, sizeof(sa));
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sa.sa_handler = func;
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sigemptyset(&sa.sa_mask);
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for (i = 0; i < sizeof(handle_sigs) / sizeof(handle_sigs[0]); i++)
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if (sigaction(handle_sigs[i], &sa, NULL) == -1)
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return signal_handle(signal_handler);
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return signal_handle(SIG_DFL);