| Russ Dill | 4e864a3 | 2003-12-18 22:25:38 +0000 | [diff] [blame] | 1 | /* signalpipe.c |
| 2 | * |
| 3 | * Signal pipe infastructure. A reliable way of delivering signals. |
| 4 | * |
| 5 | * Russ Dill <Russ.Dill@asu.edu> Decemeber 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 <signal.h> |
| 24 | #include <sys/types.h> |
| 25 | #include <sys/socket.h> |
| 26 | #include <sys/select.h> |
| 27 | |
| 28 | |
| 29 | #include "signalpipe.h" |
| 30 | #include "common.h" |
| 31 | |
| 32 | static int signal_pipe[2]; |
| 33 | |
| 34 | static void signal_handler(int sig) |
| 35 | { |
| 36 | if (send(signal_pipe[1], &sig, sizeof(sig), MSG_DONTWAIT) < 0) |
| 37 | DEBUG(LOG_ERR, "Could not send signal: %m"); |
| 38 | } |
| 39 | |
| 40 | |
| 41 | /* Call this before doing anything else. Sets up the socket pair |
| 42 | * and installs the signal handler */ |
| 43 | void udhcp_sp_setup(void) |
| 44 | { |
| 45 | socketpair(AF_UNIX, SOCK_STREAM, 0, signal_pipe); |
| 46 | signal(SIGUSR1, signal_handler); |
| 47 | signal(SIGUSR2, signal_handler); |
| 48 | signal(SIGTERM, signal_handler); |
| 49 | } |
| 50 | |
| 51 | |
| 52 | /* Quick little function to setup the rfds. Will return the |
| 53 | * max_fd for use with select. Limited in that you can only pass |
| 54 | * one extra fd */ |
| 55 | int udhcp_sp_fd_set(fd_set *rfds, int extra_fd) |
| 56 | { |
| 57 | FD_ZERO(rfds); |
| 58 | FD_SET(signal_pipe[0], rfds); |
| 59 | if (extra_fd >= 0) FD_SET(extra_fd, rfds); |
| 60 | return signal_pipe[0] > extra_fd ? signal_pipe[0] : extra_fd; |
| 61 | } |
| 62 | |
| 63 | |
| 64 | /* Read a signal from the signal pipe. Returns 0 if there is |
| 65 | * no signal, -1 on error (and sets errno appropriately), and |
| 66 | * your signal on success */ |
| 67 | int udhcp_sp_read(fd_set *rfds) |
| 68 | { |
| 69 | int sig; |
| 70 | |
| 71 | if (!FD_ISSET(signal_pipe[0], rfds)) |
| 72 | return 0; |
| 73 | |
| 74 | if (read(signal_pipe[0], &sig, sizeof(sig)) < 0) |
| 75 | return -1; |
| 76 | |
| 77 | return sig; |
| 78 | } |