root/lm-sensors/trunk/prog/sensord/sensord.c

/*
 * sensord
 *
 * A daemon that periodically logs sensor information to syslog.
 *
 * Copyright (c) 1999-2002 Merlin Hughes <merlin@merlin.org>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA.
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <limits.h>
#include <string.h>
#include <signal.h>
#include <syslog.h>
#include <unistd.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "args.h"
#include "sensord.h"

static int logOpened = 0;

static volatile sig_atomic_t done = 0;
static volatile sig_atomic_t reload = 0;

#define LOG_BUFFER 4096

#include <stdarg.h>

void sensorLog(int priority, const char *fmt, ...)
{
        static char buffer[1 + LOG_BUFFER];
        va_list ap;
        va_start(ap, fmt);
        vsnprintf(buffer, LOG_BUFFER, fmt, ap);
        buffer[LOG_BUFFER] = '\0';
        va_end(ap);
        if (sensord_args.debug || (priority < LOG_DEBUG)) {
                if (logOpened) {
                        syslog(priority, "%s", buffer);
                } else {
                        fprintf(stderr, "%s\n", buffer);
                        fflush(stderr);
                }
        }
}

static void signalHandler(int sig)
{
        switch (sig) {
        case SIGTERM:
                done = 1;
                break;
        case SIGHUP:
                reload = 1;
                break;
        }
}

static int sensord(void)
{
        int ret = 0;
        int scanValue = 0, logValue = 0;
        /*
         * First RRD update at next RRD timeslot to prevent failures due
         * one timeslot updated twice on restart for example.
         */
        int rrdValue = sensord_args.rrdTime - time(NULL) %
                sensord_args.rrdTime;

        sensorLog(LOG_INFO, "sensord started");

        while (!done) {
                if (reload) {
                        ret = reloadLib(sensord_args.cfgFile);
                        if (ret)
                                sensorLog(LOG_NOTICE, "configuration reload"
                                          " error");
                        reload = 0;
                }
                if (sensord_args.scanTime && (scanValue <= 0)) {
                        if ((ret = scanChips()))
                                sensorLog(LOG_NOTICE,
                                          "sensor scan error (%d)", ret);
                        scanValue += sensord_args.scanTime;
                }
                if (sensord_args.logTime && (logValue <= 0)) {
                        if ((ret = readChips()))
                                sensorLog(LOG_NOTICE,
                                          "sensor read error (%d)", ret);
                        logValue += sensord_args.logTime;
                }
                if (sensord_args.rrdTime && sensord_args.rrdFile &&
                    (rrdValue <= 0)) {
                        if ((ret = rrdUpdate()))
                                sensorLog(LOG_NOTICE,
                                          "rrd update error (%d)", ret);
                        /*
                         * The amount of time to wait is computed using the
                         * same method as in RRD instead of simply adding the
                         * interval.
                         */
                        rrdValue = sensord_args.rrdTime - time(NULL) %
                                sensord_args.rrdTime;
                }
                if (!done) {
                        int a = sensord_args.logTime ? logValue : INT_MAX;
                        int b = sensord_args.scanTime ? scanValue : INT_MAX;
                        int c = (sensord_args.rrdTime && sensord_args.rrdFile)
                                ? rrdValue : INT_MAX;
                        int sleepTime = (a < b) ? ((a < c) ? a : c) :
                                ((b < c) ? b : c);
                        sleep(sleepTime);
                        scanValue -= sleepTime;
                        logValue -= sleepTime;
                        rrdValue -= sleepTime;
                }
        }

        sensorLog(LOG_INFO, "sensord stopped");

        return ret;
}

static void openLog(void)
{
        openlog("sensord", 0, sensord_args.syslogFacility);
        logOpened = 1;
}

static void install_sighandler(void)
{
        struct sigaction new;
        int ret;

        memset(&new, 0, sizeof(struct sigaction));
        new.sa_handler = signalHandler;
        sigemptyset(&new.sa_mask);
        new.sa_flags = SA_RESTART;

        ret = sigaction(SIGTERM, &new, NULL);
        if (ret == -1) {
                fprintf(stderr, "Could not set sighandler for SIGTERM: %s\n",
                        strerror(errno));
                exit(EXIT_FAILURE);
        }

        ret = sigaction(SIGHUP, &new, NULL);
        if (ret == -1) {
                fprintf(stderr, "Could not set sighandler for SIGHUP: %s\n",
                        strerror(errno));
                exit(EXIT_FAILURE);
        }
}

static void daemonize(void)
{
        int pid;
        struct stat fileStat;
        FILE *file;

        if (chdir("/") < 0) {
                perror("chdir()");
                exit(EXIT_FAILURE);
        }

        if (!(stat(sensord_args.pidFile, &fileStat)) &&
            ((!S_ISREG(fileStat.st_mode)) || (fileStat.st_size > 11))) {
                fprintf(stderr,
                        "Error: PID file `%s' already exists and looks suspicious.\n",
                        sensord_args.pidFile);
                exit(EXIT_FAILURE);
        }

        if (!(file = fopen(sensord_args.pidFile, "w"))) {
                fprintf(stderr, "fopen(\"%s\"): %s\n", sensord_args.pidFile,
                        strerror(errno));
                exit(EXIT_FAILURE);
        }

        install_sighandler();

        if ((pid = fork()) == -1) {
                perror("fork()");
                exit(EXIT_FAILURE);
        } else if (pid != 0) {
                fprintf(file, "%d\n", pid);
                fclose(file);

                freeChips();
                if (unloadLib())
                        exit(EXIT_FAILURE);

                exit(EXIT_SUCCESS);
        }

        if (setsid() < 0) {
                perror("setsid()");
                exit(EXIT_FAILURE);
        }

        fclose(file);
        close(STDIN_FILENO);
        close(STDOUT_FILENO);
        close(STDERR_FILENO);
}

static void undaemonize(void)
{
        unlink(sensord_args.pidFile);
        closelog();
}

int main(int argc, char **argv)
{
        int ret = 0;

        if (parseArgs(argc, argv) ||
            parseChips(argc, argv))
                exit(EXIT_FAILURE);

        if (loadLib(sensord_args.cfgFile)) {
                freeChips();
                exit(EXIT_FAILURE);
        }

        if (!sensord_args.doCGI)
                openLog();

        if (sensord_args.rrdFile) {
                ret = rrdInit();
                if (ret) {
                        freeChips();
                        exit(EXIT_FAILURE);
                }
        }

        if (sensord_args.doCGI) {
                ret = rrdCGI();
        } else {
                daemonize();
                ret = sensord();
                undaemonize();
        }

        freeChips();
        if (unloadLib())
                exit(EXIT_FAILURE);

        return ret;
}