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 <syslog.h>
35 #include <unistd.h>
36
37 #include "common.h"
38 #include "signals.h"
39
40 static int signal_pipe[2];
41
42 static const int handle_sigs[] = {
43 SIGHUP,
44 SIGALRM,
45 SIGTERM,
46 SIGINT
47 };
48
49 static void
signal_handler(int sig)50 signal_handler(int sig)
51 {
52 int serrno = errno;
53
54 if (write(signal_pipe[1], &sig, sizeof(sig)) != sizeof(sig))
55 syslog(LOG_ERR, "write signal %d: %s", sig, strerror(errno));
56 /* Restore errno */
57 errno = serrno;
58 }
59
60 int
signal_fd(void)61 signal_fd(void)
62 {
63 return (signal_pipe[0]);
64 }
65
66 /* Read a signal from the signal pipe. Returns 0 if there is
67 * no signal, -1 on error (and sets errno appropriately), and
68 * your signal on success */
69 int
signal_read(void)70 signal_read(void)
71 {
72 int sig = -1;
73 char buf[16];
74 ssize_t bytes;
75
76 memset(buf, 0, sizeof(buf));
77 bytes = read(signal_pipe[0], buf, sizeof(buf));
78 if (bytes >= 0 && (size_t)bytes >= sizeof(sig))
79 memcpy(&sig, buf, sizeof(sig));
80 return sig;
81 }
82
83 /* Call this before doing anything else. Sets up the socket pair
84 * and installs the signal handler */
85 int
signal_init(void)86 signal_init(void)
87 {
88 if (pipe(signal_pipe) == -1)
89 return -1;
90 /* Don't block on read */
91 if (set_nonblock(signal_pipe[0]) == -1)
92 return -1;
93 /* Stop any scripts from inheriting us */
94 if (set_cloexec(signal_pipe[0]) == -1)
95 return -1;
96 if (set_cloexec(signal_pipe[1]) == -1)
97 return -1;
98 return 0;
99 }
100
101 static int
signal_handle(void (* func)(int))102 signal_handle(void (*func)(int))
103 {
104 unsigned int i;
105 struct sigaction sa;
106
107 memset(&sa, 0, sizeof(sa));
108 sa.sa_handler = func;
109 sigemptyset(&sa.sa_mask);
110
111 for (i = 0; i < sizeof(handle_sigs) / sizeof(handle_sigs[0]); i++)
112 if (sigaction(handle_sigs[i], &sa, NULL) == -1)
113 return -1;
114 return 0;
115 }
116
117 int
signal_setup(void)118 signal_setup(void)
119 {
120 return signal_handle(signal_handler);
121 }
122
123 int
signal_reset(void)124 signal_reset(void)
125 {
126 return signal_handle(SIG_DFL);
127 }
128