1/*
2 * dhcpcd - DHCP client daemon
3 * Copyright (c) 2006-2009 Roy Marples <roy@marples.name>
4 * All rights reserved
5
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/types.h>
29#include <sys/socket.h>
30
31#include <errno.h>
32#include <signal.h>
33#include <string.h>
34#include <syslog.h>
35#include <unistd.h>
36
37#include "common.h"
38#include "signals.h"
39
40static int signal_pipe[2];
41
42static const int handle_sigs[] = {
43	SIGALRM,
44	SIGHUP,
45	SIGINT,
46	SIGPIPE,
47	SIGTERM,
48	SIGUSR1,
49};
50
51static void
52signal_handler(int sig)
53{
54	int serrno = errno;
55
56	if (write(signal_pipe[1], &sig, sizeof(sig)) != sizeof(sig))
57		syslog(LOG_ERR, "failed to write signal %d: %m", sig);
58	/* Restore errno */
59	errno = serrno;
60}
61
62/* Read a signal from the signal pipe. Returns 0 if there is
63 * no signal, -1 on error (and sets errno appropriately), and
64 * your signal on success */
65int
66signal_read(void)
67{
68	int sig = -1;
69	char buf[16];
70	ssize_t bytes;
71
72	memset(buf, 0, sizeof(buf));
73	bytes = read(signal_pipe[0], buf, sizeof(buf));
74	if (bytes >= 0 && (size_t)bytes >= sizeof(sig))
75		memcpy(&sig, buf, sizeof(sig));
76	return sig;
77}
78
79/* Call this before doing anything else. Sets up the socket pair
80 * and installs the signal handler */
81int
82signal_init(void)
83{
84	if (pipe(signal_pipe) == -1)
85		return -1;
86	/* Don't block on read */
87	if (set_nonblock(signal_pipe[0]) == -1)
88		return -1;
89	/* Stop any scripts from inheriting us */
90	if (set_cloexec(signal_pipe[0]) == -1)
91		return -1;
92	if (set_cloexec(signal_pipe[1]) == -1)
93		return -1;
94	return signal_pipe[0];
95}
96
97static int
98signal_handle(void (*func)(int))
99{
100	unsigned int i;
101	struct sigaction sa;
102
103	memset(&sa, 0, sizeof(sa));
104	sa.sa_handler = func;
105	sigemptyset(&sa.sa_mask);
106
107	for (i = 0; i < sizeof(handle_sigs) / sizeof(handle_sigs[0]); i++)
108		if (sigaction(handle_sigs[i], &sa, NULL) == -1)
109			return -1;
110	return 0;
111}
112
113int
114signal_setup(void)
115{
116	return signal_handle(signal_handler);
117}
118
119int
120signal_reset(void)
121{
122	return signal_handle(SIG_DFL);
123}
124
125