source: trunk/mindi-busybox/networking/udhcp/signalpipe.c @ 904

Last change on this file since 904 was 821, checked in by Bruno Cornec, 14 years ago

Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)

File size: 2.3 KB
Line 
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
33static int signal_pipe[2];
34
35static 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 */
44void 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 */
58int 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 */
73int 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}
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