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/*
* powerd Monitor the DCD line of a serial port connected to
* an UPS. If the power goes down, notify init.
* If the power comes up again, notify init again.
* As long as the power is OK, the DCD line should be
* "HIGH". When the power fails, DCD should go "LOW".
* Powerd keeps DTR high so that you can connect
* DCD and DTR with a resistor of 10 Kilo Ohm and let the
* UPS or some relais pull the DCD line to ground.
* You also need to connect DTR and DSR together. This
* way, powerd can check now and then if DSR is high
* so it knows the UPS is connected!!
*
* Usage: powerd /dev/cua4 (or any other serial device).
*
* Author: Miquel van Smoorenburg, <miquels@drinkel.cistron.nl>.
*
* Version: 1.31, 29-Feb-1996.
*
* This program was originally written for my employer,
* ** Cistron Electronics **
* who has given kind permission to release this program
* for general puppose.
*
* Copyright 1991-1996 Cistron Electronics.
*
* 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.
*/
/* Use the new way of communicating with init. */
#define NEWINIT
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <signal.h>
#include <syslog.h>
#include <string.h>
#include "paths.h"
#ifdef NEWINIT
#include "initreq.h"
#endif
#ifndef SIGPWR
# define SIGPWR SIGUSR1
#endif
#ifdef NEWINIT
void alrm_handler()
{
}
#endif
/* Tell init the power has either gone or is back. */
void powerfail(ok)
int ok;
{
int fd;
#ifdef NEWINIT
struct init_request req;
/* Fill out the request struct. */
memset(&req, 0, sizeof(req));
req.magic = INIT_MAGIC;
req.cmd = ok ? INIT_CMD_POWEROK : INIT_CMD_POWERFAIL;
/* Open the fifo (with timeout) */
signal(SIGALRM, alrm_handler);
alarm(3);
if ((fd = open(INIT_FIFO, O_WRONLY)) >= 0
&& write(fd, &req, sizeof(req)) == sizeof(req)) {
close(fd);
return;
}
/* Fall through to the old method.. */
#endif
/* Create an info file for init. */
unlink(PWRSTAT);
if ((fd = open(PWRSTAT, O_CREAT|O_WRONLY, 0644)) >= 0) {
if (ok)
write(fd, "OK\n", 3);
else
write(fd, "FAIL\n", 5);
close(fd);
}
kill(1, SIGPWR);
}
/* Main program. */
int main(int argc, char **argv)
{
int fd;
int dtr_bit = TIOCM_DTR;
int flags;
int status, oldstat = -1;
int count = 0;
int tries = 0;
if (argc < 2) {
fprintf(stderr, "Usage: powerd <device>\n");
exit(1);
}
/* Start syslog. */
openlog("powerd", LOG_CONS|LOG_PERROR, LOG_DAEMON);
/* Open monitor device. */
if ((fd = open(argv[1], O_RDWR | O_NDELAY)) < 0) {
syslog(LOG_ERR, "%s: %s", argv[1], sys_errlist[errno]);
closelog();
exit(1);
}
/* Line is opened, so DTR is high. Force it anyway to be sure. */
ioctl(fd, TIOCMBIS, &dtr_bit);
/* Daemonize. */
switch(fork()) {
case 0: /* Child */
closelog();
setsid();
break;
case -1: /* Error */
syslog(LOG_ERR, "can't fork.");
closelog();
exit(1);
default: /* Parent */
closelog();
exit(0);
}
/* Restart syslog. */
openlog("powerd", LOG_CONS, LOG_DAEMON);
/* Now sample the DCD line. */
while(1) {
/* Get the status. */
ioctl(fd, TIOCMGET, &flags);
/* Check the connection: DSR should be high. */
tries = 0;
while((flags & TIOCM_DSR) == 0) {
/* Keep on trying, and warn every two minutes. */
if ((tries % 60) == 0)
syslog(LOG_ALERT, "UPS connection error");
sleep(2);
tries++;
ioctl(fd, TIOCMGET, &flags);
}
if (tries > 0)
syslog(LOG_ALERT, "UPS connection OK");
/* Calculate present status. */
status = (flags & TIOCM_CAR);
/* Did DCD drop to zero? Then the power has failed. */
if (oldstat != 0 && status == 0) {
count++;
if (count > 3)
powerfail(0);
else {
sleep(1);
continue;
}
}
/* Did DCD come up again? Then the power is back. */
if (oldstat == 0 && status > 0) {
count++;
if (count > 3)
powerfail(1);
else {
sleep(1);
continue;
}
}
/* Reset count, remember status and sleep 2 seconds. */
count = 0;
oldstat = status;
sleep(2);
}
/* Never happens */
return(0);
}
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