1/* 2 * dhcpcd - DHCP client daemon 3 * Copyright (c) 2006-2009 Roy Marples <roy@marples.name> 4 * All rights reserved 5 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28#include <sys/types.h> 29#include <sys/socket.h> 30 31#include <errno.h> 32#include <signal.h> 33#include <string.h> 34#include <syslog.h> 35#include <unistd.h> 36 37#include "common.h" 38#include "signals.h" 39 40static int signal_pipe[2]; 41 42static const int handle_sigs[] = { 43 SIGALRM, 44 SIGHUP, 45 SIGINT, 46 SIGPIPE, 47 SIGTERM, 48 SIGUSR1, 49}; 50 51static void 52signal_handler(int sig) 53{ 54 int serrno = errno; 55 56 if (write(signal_pipe[1], &sig, sizeof(sig)) != sizeof(sig)) 57 syslog(LOG_ERR, "failed to write signal %d: %m", sig); 58 /* Restore errno */ 59 errno = serrno; 60} 61 62/* Read a signal from the signal pipe. Returns 0 if there is 63 * no signal, -1 on error (and sets errno appropriately), and 64 * your signal on success */ 65int 66signal_read(void) 67{ 68 int sig = -1; 69 char buf[16]; 70 ssize_t bytes; 71 72 memset(buf, 0, sizeof(buf)); 73 bytes = read(signal_pipe[0], buf, sizeof(buf)); 74 if (bytes >= 0 && (size_t)bytes >= sizeof(sig)) 75 memcpy(&sig, buf, sizeof(sig)); 76 return sig; 77} 78 79/* Call this before doing anything else. Sets up the socket pair 80 * and installs the signal handler */ 81int 82signal_init(void) 83{ 84 if (pipe(signal_pipe) == -1) 85 return -1; 86 /* Don't block on read */ 87 if (set_nonblock(signal_pipe[0]) == -1) 88 return -1; 89 /* Stop any scripts from inheriting us */ 90 if (set_cloexec(signal_pipe[0]) == -1) 91 return -1; 92 if (set_cloexec(signal_pipe[1]) == -1) 93 return -1; 94 return signal_pipe[0]; 95} 96 97static int 98signal_handle(void (*func)(int)) 99{ 100 unsigned int i; 101 struct sigaction sa; 102 103 memset(&sa, 0, sizeof(sa)); 104 sa.sa_handler = func; 105 sigemptyset(&sa.sa_mask); 106 107 for (i = 0; i < sizeof(handle_sigs) / sizeof(handle_sigs[0]); i++) 108 if (sigaction(handle_sigs[i], &sa, NULL) == -1) 109 return -1; 110 return 0; 111} 112 113int 114signal_setup(void) 115{ 116 return signal_handle(signal_handler); 117} 118 119int 120signal_reset(void) 121{ 122 return signal_handle(SIG_DFL); 123} 124 125