external/bsd/dhcpcd/dist/signals.c

   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
  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