| /* vi: set sw=4 ts=4: */ |
| /* |
| * Signal pipe infrastructure. A reliable way of delivering signals. |
| * |
| * Russ Dill <Russ.Dill@asu.edu> December 2003 |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| */ |
| #include "common.h" |
| |
| /* Global variable: we access it from signal handler */ |
| static struct fd_pair signal_pipe; |
| |
| static void signal_handler(int sig) |
| { |
| unsigned char ch = sig; /* use char, avoid dealing with partial writes */ |
| if (write(signal_pipe.wr, &ch, 1) != 1) |
| bb_perror_msg("can't send signal"); |
| } |
| |
| /* Call this before doing anything else. Sets up the socket pair |
| * and installs the signal handler */ |
| void FAST_FUNC udhcp_sp_setup(void) |
| { |
| /* was socketpair, but it needs AF_UNIX in kernel */ |
| xpiped_pair(signal_pipe); |
| close_on_exec_on(signal_pipe.rd); |
| close_on_exec_on(signal_pipe.wr); |
| ndelay_on(signal_pipe.wr); |
| bb_signals(0 |
| + (1 << SIGUSR1) |
| + (1 << SIGUSR2) |
| + (1 << SIGTERM) |
| , signal_handler); |
| } |
| |
| /* Quick little function to setup the rfds. Will return the |
| * max_fd for use with select. Limited in that you can only pass |
| * one extra fd */ |
| int FAST_FUNC udhcp_sp_fd_set(fd_set *rfds, int extra_fd) |
| { |
| FD_ZERO(rfds); |
| FD_SET(signal_pipe.rd, rfds); |
| if (extra_fd >= 0) { |
| close_on_exec_on(extra_fd); |
| FD_SET(extra_fd, rfds); |
| } |
| return signal_pipe.rd > extra_fd ? signal_pipe.rd : extra_fd; |
| } |
| |
| /* Read a signal from the signal pipe. Returns 0 if there is |
| * no signal, -1 on error (and sets errno appropriately), and |
| * your signal on success */ |
| int FAST_FUNC udhcp_sp_read(const fd_set *rfds) |
| { |
| unsigned char sig; |
| |
| if (!FD_ISSET(signal_pipe.rd, rfds)) |
| return 0; |
| |
| if (safe_read(signal_pipe.rd, &sig, 1) != 1) |
| return -1; |
| |
| return sig; |
| } |
