Source Code 1992 March/Source_Code_CD-ROM_Walnut_Creek_March_1992.iso/usenet/altsrcs/3/3163/funcs.c

C/C++ Source or Header | 1991-04-04 | 4.6 KB | 276 lines

/*
**    f u n c s . c
**
**    functions for UPS monitor daemon
**
**    Arthur W. Neilson III
**    [e-mail]
**    Sat Mar 30 1991
*/

#include "common.h"

/*
**    g e t v a r s
**
**    retrieve environment variables
*/
void
getvars()
{
    char   *s, *getenv();

    if ((s = getenv(UPSPORT)) != NULL)
        ups_port = s;
    if ((s = getenv(UPSSHUT)) != NULL)
        ups_shut = s;
    if ((s = getenv(UPSLOG)) != NULL)
        ups_log = s;
    if ((s = getenv(UPSTIME)) != NULL)
        ups_time = atoi(s) * SECS_PER_MIN;
}

/*
**    g e t o p t i o n s
**
**    retrieve and process command line options
*/
void
getoptions(ac, av)
int     ac;
char   *av[];
{
    int     c;

    void    usage();

    extern char *optarg;
    extern int optind, opterr;

    /* parse the command line */
    while ((c = getopt(ac, av, "d:c:l:t:")) != EOF)
        switch (c) {
        case 'd':    /* device option */
            ups_port = optarg;
            break;
        case 'c':    /* command option */
            ups_shut = optarg;
            break;
        case 'l':    /* logfile option */
            ups_log = optarg;
            break;
        case 't':    /* time option */
            ups_time = atoi(optarg) * SECS_PER_MIN;
            break;
        case '\?':    /* illegal option */
            usage(av[0]);
            exit(1);
        }
}

/*
**    c h k o p t i o n s
**
**    check runtime options
*/
void
chkoptions()
{
    struct stat st;
    char   *p, buf[64];

    /* UPS port must exist */
    if (stat(ups_port, &st) == ERR) {
        perror(ups_port);
        exit(1);
    }
    /* and must be character special */
    if ((st.st_mode & S_IFMT) != S_IFCHR) {
        fprintf(stderr, "%s not character special\n", ups_port);
        exit(1);
    }
    /* get command name out of shutdown command */
    strcpy(buf, ups_shut);
    if ((p = strtok(buf, " ")) == NULL)
        p = buf;

    /* shutdown command must exist */
    if (stat(p, &st) == ERR) {
        perror(ups_shut);
        exit(1);
    }
    /* and must be readable/executable by owner */
    if (!(st.st_mode & SHUT_PERMS)) {
        fprintf(stderr, "%s must be readable/executable by owner\n", ups_port);
        exit(1);
    }
    /* delay time must be > 0 and <= MAX_TIME */
    if (ups_time < 1 || ups_time > MAX_TIME) {
        fprintf(stderr, "time must be between 1 and %d\n", MAX_TIME);
        exit(1);
    }
}

/*
**    m k d a e m o n
**
**    create daemon process
*/
void
mkdaemon()
{
    char    c;

    void    sigcatch();
    void    writelog();
    void    shutdown();

    if (!fork()) {

        /* close standard files */
        close(0);    /* stdin */
        close(1);    /* stdout */
        close(2);    /* stderr */

        setpgrp();    /* disassociate from terminal */

        /* ignore interrupts */
        signal(SIGHUP, SIG_IGN);
        signal(SIGINT, SIG_IGN);
        signal(SIGQUIT, SIG_IGN);

        /* catch termination signal */
        signal(SIGTERM, sigcatch);

        /* and shutdown on alarm */
        signal(SIGALRM, shutdown);

        /* open log file for append */
        if ((log_fd = open(ups_log, LOG_FLAGS, LOG_PERMS)) == ERR)
            exit(1);

        writelog(START_MSG);

        /* open blocks on UPS switch to battery */
        if ((ups_fd = open(ups_port, O_RDWR)) == ERR) {
            writelog(OPEN_MSG);
            exit(1);
        }
        writelog(BATTERY_MSG);

        alarm(ups_time);/* set the alarm clock */

        /* read blocks on UPS switch to online */
        if (read(ups_fd, &c, 1) == ERR)
            exit(1);

        writelog(ONLINE_MSG);

        close(log_fd);
        close(ups_fd);

        mkdaemon();
    }
}

/*
**    s i g c a t c h
**
**    catch termination signal
*/
void
sigcatch()
{
    writelog(TERM_MSG);
    close(log_fd);
    close(ups_fd);
    exit(1);
}

/*
**    w r i t e l o g
**
**    write message to the UPS log file
*/
void
writelog(msg)
char   *msg;
{
    struct tm *t;
    time_t  ticks;
    char   *p, ctime_buf[26];
    char    msg_buf[80];

    time(&ticks);
    strcpy(ctime_buf, ctime(&ticks));

    /* find newline in buffer */
    if ((p = strrchr(ctime_buf, '\n')) != NULL)
        *p = NULL;    /* and zap it */

    sprintf(msg_buf, "%s -- %s\n", ctime_buf, msg);
    write(log_fd, msg_buf, strlen(msg_buf));
}

/*
**    s h u t d o w n
**
**    shutdown the system
*/
void
shutdown()
{
    void    attach();

    writelog(SHUTDOWN_MSG);

    close(log_fd);
    close(ups_fd);

    attach(CONSOLE);

    chdir(ROOT);

    /* execute shutdown command */
    execlp(SH, SH, "-c", ups_shut, NULL);
}

/*
**    a t t a c h
**
**    attach standard i/o to a device
*/
void
attach(dev)
char   *dev;
{
    int     fd;

    /* close standard files */
    close(0);        /* stdin */
    close(1);        /* stdout */
    close(2);        /* stderr */

    /* attach stdin to named device */
    if ((fd = open(dev, O_RDWR)) == ERR)
        exit(1);
    dup(fd);        /* and stdout */
    dup(fd);        /* and stderr */
}

/*
**    u s a g e
**
**    display program usage
*/
void
usage(s)
char   *s;
{
    fprintf(stderr, "usage: %s [-d tty][-c cmd][-l log][-t min]\n", s);
    fprintf(stderr, "\t-d tty\t\tpathname of UPS device\n");
    fprintf(stderr, "\t-c cmd\t\tpathname of shutdown command\n");
    fprintf(stderr, "\t-l log\t\tpathname of UPS log file\n");
    fprintf(stderr, "\t-t min\t\tdelay time in minutes\n");
}