Home | History | Annotate | Download | only in dhcpcd 
      1 /*
      2  * dhcpcd - DHCP client daemon
      3  * Copyright (c) 2006-2009 Roy Marples <roy (at) 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 
     40 static int signal_pipe[2];
     41 
     42 static const int handle_sigs[] = {
     43 	SIGALRM,
     44 	SIGHUP,
     45 	SIGINT,
     46 	SIGPIPE,
     47 	SIGTERM,
     48 	SIGUSR1,
     49 };
     50 
     51 static void
     52 signal_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 */
     65 int
     66 signal_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 */
     81 int
     82 signal_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 
     97 static int
     98 signal_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 
    113 int
    114 signal_setup(void)
    115 {
    116 	return signal_handle(signal_handler);
    117 }
    118 
    119 int
    120 signal_reset(void)
    121 {
    122 	return signal_handle(SIG_DFL);
    123 }
    124 
    125