1 | /* signalpipe.c
|
---|
2 | *
|
---|
3 | * Signal pipe infrastructure. A reliable way of delivering signals.
|
---|
4 | *
|
---|
5 | * Russ Dill <Russ.Dill@asu.edu> December 2003
|
---|
6 | *
|
---|
7 | * This program is free software; you can redistribute it and/or modify
|
---|
8 | * it under the terms of the GNU General Public License as published by
|
---|
9 | * the Free Software Foundation; either version 2 of the License, or
|
---|
10 | * (at your option) any later version.
|
---|
11 | *
|
---|
12 | * This program is distributed in the hope that it will be useful,
|
---|
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
|
---|
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
---|
15 | * GNU General Public License for more details.
|
---|
16 | *
|
---|
17 | * You should have received a copy of the GNU General Public License
|
---|
18 | * along with this program; if not, write to the Free Software
|
---|
19 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
---|
20 | */
|
---|
21 |
|
---|
22 | #include <unistd.h>
|
---|
23 | #include <fcntl.h>
|
---|
24 | #include <signal.h>
|
---|
25 | #include <sys/types.h>
|
---|
26 | #include <sys/socket.h>
|
---|
27 | #include <sys/select.h>
|
---|
28 |
|
---|
29 |
|
---|
30 | #include "signalpipe.h"
|
---|
31 | #include "common.h"
|
---|
32 |
|
---|
33 | static int signal_pipe[2];
|
---|
34 |
|
---|
35 | static void signal_handler(int sig)
|
---|
36 | {
|
---|
37 | if (send(signal_pipe[1], &sig, sizeof(sig), MSG_DONTWAIT) < 0)
|
---|
38 | DEBUG(LOG_ERR, "Could not send signal: %m");
|
---|
39 | }
|
---|
40 |
|
---|
41 |
|
---|
42 | /* Call this before doing anything else. Sets up the socket pair
|
---|
43 | * and installs the signal handler */
|
---|
44 | void udhcp_sp_setup(void)
|
---|
45 | {
|
---|
46 | socketpair(AF_UNIX, SOCK_STREAM, 0, signal_pipe);
|
---|
47 | fcntl(signal_pipe[0], F_SETFD, FD_CLOEXEC);
|
---|
48 | fcntl(signal_pipe[1], F_SETFD, FD_CLOEXEC);
|
---|
49 | signal(SIGUSR1, signal_handler);
|
---|
50 | signal(SIGUSR2, signal_handler);
|
---|
51 | signal(SIGTERM, signal_handler);
|
---|
52 | }
|
---|
53 |
|
---|
54 |
|
---|
55 | /* Quick little function to setup the rfds. Will return the
|
---|
56 | * max_fd for use with select. Limited in that you can only pass
|
---|
57 | * one extra fd */
|
---|
58 | int udhcp_sp_fd_set(fd_set *rfds, int extra_fd)
|
---|
59 | {
|
---|
60 | FD_ZERO(rfds);
|
---|
61 | FD_SET(signal_pipe[0], rfds);
|
---|
62 | if (extra_fd >= 0) {
|
---|
63 | fcntl(extra_fd, F_SETFD, FD_CLOEXEC);
|
---|
64 | FD_SET(extra_fd, rfds);
|
---|
65 | }
|
---|
66 | return signal_pipe[0] > extra_fd ? signal_pipe[0] : extra_fd;
|
---|
67 | }
|
---|
68 |
|
---|
69 |
|
---|
70 | /* Read a signal from the signal pipe. Returns 0 if there is
|
---|
71 | * no signal, -1 on error (and sets errno appropriately), and
|
---|
72 | * your signal on success */
|
---|
73 | int udhcp_sp_read(fd_set *rfds)
|
---|
74 | {
|
---|
75 | int sig;
|
---|
76 |
|
---|
77 | if (!FD_ISSET(signal_pipe[0], rfds))
|
---|
78 | return 0;
|
---|
79 |
|
---|
80 | if (read(signal_pipe[0], &sig, sizeof(sig)) < 0)
|
---|
81 | return -1;
|
---|
82 |
|
---|
83 | return sig;
|
---|
84 | }
|
---|