obsolete/powerd.c

   1 /*
   2  * powerd       Monitor the DCD line of a serial port connected to
   3  *              an UPS. If the power goes down, notify init.
   4  *              If the power comes up again, notify init again.
   5  *              As long as the power is OK, the DCD line should be
   6  *              "HIGH". When the power fails, DCD should go "LOW".
   7  *              Powerd keeps DTR high so that you can connect
   8  *              DCD and DTR with a resistor of 10 Kilo Ohm and let the
   9  *              UPS or some relais pull the DCD line to ground.
  10  *              You also need to connect DTR and DSR together. This
  11  *              way, powerd can check now and then if DSR is high
  12  *              so it knows the UPS is connected!!
  13  *
  14  * Usage:       powerd /dev/cua4 (or any other serial device).
  15  *
  16  * Author:      Miquel van Smoorenburg, <miquels@drinkel.cistron.nl>.
  17  *
  18  * Version:     1.31,  29-Feb-1996.
  19  *
  20  *              This program was originally written for my employer,
  21  *                      ** Cistron Electronics **
  22  *              who has given kind permission to release this program
  23  *              for general puppose.
  24  *
  25  *              Copyright (C) 1991-1996 Cistron Electronics.
  26  *
  27  *              This program is free software; you can redistribute it and/or modify
  28  *              it under the terms of the GNU General Public License as published by
  29  *              the Free Software Foundation; either version 2 of the License, or
  30  *              (at your option) any later version.
  31  *
  32  *              This program is distributed in the hope that it will be useful,
  33  *              but WITHOUT ANY WARRANTY; without even the implied warranty of
  34  *              MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  35  *              GNU General Public License for more details.
  36  *
  37  *              You should have received a copy of the GNU General Public License
  38  *              along with this program; if not, write to the Free Software
  39  *              Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  40  */
  41
  42 /* Use the new way of communicating with init. */
  43 #define NEWINIT
  44
  45 #include <sys/types.h>
  46 #include <sys/stat.h>
  47 #include <sys/ioctl.h>
  48 #include <fcntl.h>
  49 #include <errno.h>
  50 #include <stdlib.h>
  51 #include <unistd.h>
  52 #include <stdio.h>
  53 #include <signal.h>
  54 #include <syslog.h>
  55 #include <string.h>
  56 #include "paths.h"
  57 #ifdef NEWINIT
  58 #include "initreq.h"
  59 #endif
  60
  61 #ifndef SIGPWR
  62 #  define SIGPWR SIGUSR1
  63 #endif
  64
  65 #ifdef NEWINIT
  66 void alrm_handler()
  67 {
  68 }
  69 #endif
  70
  71 /* Tell init the power has either gone or is back. */
  72 void powerfail(ok)
  73 int ok;
  74 {
  75   int fd;
  76 #ifdef NEWINIT
  77   struct init_request req;
  78
  79   /* Fill out the request struct. */
  80   memset(&req, 0, sizeof(req));
  81   req.magic = INIT_MAGIC;
  82   req.cmd   = ok ? INIT_CMD_POWEROK : INIT_CMD_POWERFAIL;
  83
  84   /* Open the fifo (with timeout) */
  85   signal(SIGALRM, alrm_handler);
  86   alarm(3);
  87   if ((fd = open(INIT_FIFO, O_WRONLY)) >= 0
  88                 && write(fd, &req, sizeof(req)) == sizeof(req)) {
  89         close(fd);
  90         return;
  91   }
  92   /* Fall through to the old method.. */
  93 #endif
  94
  95   /* Create an info file for init. */
  96   unlink(PWRSTAT);
  97   if ((fd = open(PWRSTAT, O_CREAT|O_WRONLY, 0644)) >= 0) {
  98         if (ok)
  99                 write(fd, "OK\n", 3);
 100         else
 101                 write(fd, "FAIL\n", 5);
 102         close(fd);
 103   }
 104   kill(1, SIGPWR);
 105 }
 106
 107 /* Main program. */
 108 int main(int argc, char **argv)
 109 {
 110   int fd;
 111   int dtr_bit = TIOCM_DTR;
 112   int flags;
 113   int status, oldstat = -1;
 114   int count = 0;
 115   int tries = 0;
 116
 117   if (argc < 2) {
 118         fprintf(stderr, "Usage: powerd <device>\n");
 119         exit(1);
 120   }
 121
 122   /* Start syslog. */
 123   openlog("powerd", LOG_CONS|LOG_PERROR, LOG_DAEMON);
 124
 125   /* Open monitor device. */
 126   if ((fd = open(argv[1], O_RDWR | O_NDELAY)) < 0) {
 127         syslog(LOG_ERR, "%s: %s", argv[1], sys_errlist[errno]);
 128         closelog();
 129         exit(1);
 130   }
 131
 132   /* Line is opened, so DTR is high. Force it anyway to be sure. */
 133   ioctl(fd, TIOCMBIS, &dtr_bit);
 134
 135   /* Daemonize. */
 136   switch(fork()) {
 137         case 0: /* Child */
 138                 closelog();
 139                 setsid();
 140                 break;
 141         case -1: /* Error */
 142                 syslog(LOG_ERR, "can't fork.");
 143                 closelog();
 144                 exit(1);
 145         default: /* Parent */
 146                 closelog();
 147                 exit(0);
 148   }
 149
 150   /* Restart syslog. */
 151   openlog("powerd", LOG_CONS, LOG_DAEMON);
 152
 153   /* Now sample the DCD line. */
 154   while(1) {
 155         /* Get the status. */
 156         ioctl(fd, TIOCMGET, &flags);
 157
 158         /* Check the connection: DSR should be high. */
 159         tries = 0;
 160         while((flags & TIOCM_DSR) == 0) {
 161                 /* Keep on trying, and warn every two minutes. */
 162                 if ((tries % 60) == 0)
 163                     syslog(LOG_ALERT, "UPS connection error");
 164                 sleep(2);
 165                 tries++;
 166                 ioctl(fd, TIOCMGET, &flags);
 167         }
 168         if (tries > 0)
 169                 syslog(LOG_ALERT, "UPS connection OK");
 170
 171         /* Calculate present status. */
 172         status = (flags & TIOCM_CAR);
 173
 174         /* Did DCD drop to zero? Then the power has failed. */
 175         if (oldstat != 0 && status == 0) {
 176                 count++;
 177                 if (count > 3)
 178                         powerfail(0);
 179                 else {
 180                         sleep(1);
 181                         continue;
 182                 }
 183         }
 184         /* Did DCD come up again? Then the power is back. */
 185         if (oldstat == 0 && status > 0) {
 186                 count++;
 187                 if (count > 3)
 188                         powerfail(1);
 189                 else {
 190                         sleep(1);
 191                         continue;
 192                 }
 193         }
 194         /* Reset count, remember status and sleep 2 seconds. */
 195         count = 0;
 196         oldstat = status;
 197         sleep(2);
 198   }
 199   /* Never happens */
 200   return(0);
 201 }