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
40 static int signal_pipe[2];
41
42 static const int handle_sigs[] = {
43 SIGALRM,
44 SIGHUP,
45 SIGINT,
46 SIGPIPE,
47 SIGTERM,
48 SIGUSR1,
49 };
50
51 static void
signal_handler(int sig)52 signal_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 */
65 int
signal_read(void)66 signal_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 */
81 int
signal_init(void)82 signal_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
97 static int
signal_handle(void (* func)(int))98 signal_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
113 int
signal_setup(void)114 signal_setup(void)
115 {
116 return signal_handle(signal_handler);
117 }
118
119 int
signal_reset(void)120 signal_reset(void)
121 {
122 return signal_handle(SIG_DFL);
123 }
124
125