Annotation of /trunk/mkinitrd-magellan/busybox/networking/udhcp/signalpipe.c
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Revision 532 -
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Sat Sep 1 22:45:15 2007 UTC (16 years, 9 months ago) by niro
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Sat Sep 1 22:45:15 2007 UTC (16 years, 9 months ago) by niro
File MIME type: text/plain
File size: 2167 byte(s)
-import if magellan mkinitrd; it is a fork of redhats mkinitrd-5.0.8 with all magellan patches and features; deprecates magellan-src/mkinitrd
1 | niro | 532 | /* vi: set sw=4 ts=4: */ |
2 | /* signalpipe.c | ||
3 | * | ||
4 | * Signal pipe infrastructure. A reliable way of delivering signals. | ||
5 | * | ||
6 | * Russ Dill <Russ.Dill@asu.edu> December 2003 | ||
7 | * | ||
8 | * This program is free software; you can redistribute it and/or modify | ||
9 | * it under the terms of the GNU General Public License as published by | ||
10 | * the Free Software Foundation; either version 2 of the License, or | ||
11 | * (at your option) any later version. | ||
12 | * | ||
13 | * This program is distributed in the hope that it will be useful, | ||
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
16 | * GNU General Public License for more details. | ||
17 | * | ||
18 | * You should have received a copy of the GNU General Public License | ||
19 | * along with this program; if not, write to the Free Software | ||
20 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | ||
21 | */ | ||
22 | |||
23 | #include "common.h" | ||
24 | |||
25 | |||
26 | static int signal_pipe[2]; | ||
27 | |||
28 | static void signal_handler(int sig) | ||
29 | { | ||
30 | if (send(signal_pipe[1], &sig, sizeof(sig), MSG_DONTWAIT) < 0) | ||
31 | bb_perror_msg("cannot send signal"); | ||
32 | } | ||
33 | |||
34 | |||
35 | /* Call this before doing anything else. Sets up the socket pair | ||
36 | * and installs the signal handler */ | ||
37 | void udhcp_sp_setup(void) | ||
38 | { | ||
39 | socketpair(AF_UNIX, SOCK_STREAM, 0, signal_pipe); | ||
40 | fcntl(signal_pipe[0], F_SETFD, FD_CLOEXEC); | ||
41 | fcntl(signal_pipe[1], F_SETFD, FD_CLOEXEC); | ||
42 | signal(SIGUSR1, signal_handler); | ||
43 | signal(SIGUSR2, signal_handler); | ||
44 | signal(SIGTERM, signal_handler); | ||
45 | } | ||
46 | |||
47 | |||
48 | /* Quick little function to setup the rfds. Will return the | ||
49 | * max_fd for use with select. Limited in that you can only pass | ||
50 | * one extra fd */ | ||
51 | int udhcp_sp_fd_set(fd_set *rfds, int extra_fd) | ||
52 | { | ||
53 | FD_ZERO(rfds); | ||
54 | FD_SET(signal_pipe[0], rfds); | ||
55 | if (extra_fd >= 0) { | ||
56 | fcntl(extra_fd, F_SETFD, FD_CLOEXEC); | ||
57 | FD_SET(extra_fd, rfds); | ||
58 | } | ||
59 | return signal_pipe[0] > extra_fd ? signal_pipe[0] : extra_fd; | ||
60 | } | ||
61 | |||
62 | |||
63 | /* Read a signal from the signal pipe. Returns 0 if there is | ||
64 | * no signal, -1 on error (and sets errno appropriately), and | ||
65 | * your signal on success */ | ||
66 | int udhcp_sp_read(fd_set *rfds) | ||
67 | { | ||
68 | int sig; | ||
69 | |||
70 | if (!FD_ISSET(signal_pipe[0], rfds)) | ||
71 | return 0; | ||
72 | |||
73 | if (read(signal_pipe[0], &sig, sizeof(sig)) < 0) | ||
74 | return -1; | ||
75 | |||
76 | return sig; | ||
77 | } |