1 /*
2 * dhcpcd - DHCP client daemon
3 * Copyright 2006-2008 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 <unistd.h>
35
36 #include "common.h"
37 #include "signals.h"
38
39 static int signal_pipe[2];
40
41 static const int handle_sigs[] = {
42 SIGHUP,
43 SIGALRM,
44 SIGTERM,
45 SIGINT
46 };
47
48 static void
signal_handler(int sig)49 signal_handler(int sig)
50 {
51 int serrno = errno;
52
53 write(signal_pipe[1], &sig, sizeof(sig));
54 /* Restore errno */
55 errno = serrno;
56 }
57
58 int
signal_fd(void)59 signal_fd(void)
60 {
61 return (signal_pipe[0]);
62 }
63
64 /* Read a signal from the signal pipe. Returns 0 if there is
65 * no signal, -1 on error (and sets errno appropriately), and
66 * your signal on success */
67 int
signal_read(void)68 signal_read(void)
69 {
70 int sig = -1;
71 char buf[16];
72 size_t bytes;
73
74 memset(buf, 0, sizeof(buf));
75 bytes = read(signal_pipe[0], buf, sizeof(buf));
76 if (bytes >= sizeof(sig))
77 memcpy(&sig, buf, sizeof(sig));
78 return sig;
79 }
80
81 /* Call this before doing anything else. Sets up the socket pair
82 * and installs the signal handler */
83 int
signal_init(void)84 signal_init(void)
85 {
86 if (pipe(signal_pipe) == -1)
87 return -1;
88 /* Don't block on read */
89 if (set_nonblock(signal_pipe[0]) == -1)
90 return -1;
91 /* Stop any scripts from inheriting us */
92 if (set_cloexec(signal_pipe[0]) == -1)
93 return -1;
94 if (set_cloexec(signal_pipe[1]) == -1)
95 return -1;
96 return 0;
97 }
98
99 static int
signal_handle(void (* func)(int))100 signal_handle(void (*func)(int))
101 {
102 unsigned int i;
103 struct sigaction sa;
104
105 memset(&sa, 0, sizeof(sa));
106 sa.sa_handler = func;
107 sigemptyset(&sa.sa_mask);
108
109 for (i = 0; i < sizeof(handle_sigs) / sizeof(handle_sigs[0]); i++)
110 if (sigaction(handle_sigs[i], &sa, NULL) == -1)
111 return -1;
112 return 0;
113 }
114
115 int
signal_setup(void)116 signal_setup(void)
117 {
118 return signal_handle(signal_handler);
119 }
120
121 int
signal_reset(void)122 signal_reset(void)
123 {
124 return signal_handle(SIG_DFL);
125 }
126