add directory study
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gohigh
305
study/linux-travel/MINIX-1.5/1.5/Source/commands/cron.c
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305
study/linux-travel/MINIX-1.5/1.5/Source/commands/cron.c
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/* Cron - clock daemon Author: S.R. Sampson */
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/* Cron is the clock daemon. It is typically started up from the
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* /etc/rc file by the line:
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* /usr/bin/cron
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* Cron automatically puts itself in the background, so no & is needed.
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* If cron is used, it runs all day, spending most of its time asleep.
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* Once a minute it wakes up and examines /usr/lib/crontab to see if there
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* are any commands to be executed. The format of this table is the same
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* as in UNIX, except that % is not allowed to indicate 'new line.'
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*
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* Each crontab entry has six fields:
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* minute hour day-of-the-month month day-of-the-week command
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* Each entry is checked in turn, and any entry matching the current time
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* is executed. The entry * matches anything. Some examples:
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*
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* min hr dat mo day command
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* * * * * * /usr/bin/date >/dev/tty0 #print date every minute
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* 0 * * * * /usr/bin/date >/dev/tty0 #print date on the hour
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* 30 4 * * 1-5 /bin/backup /dev/fd1 #do backup Mon-Fri at 0430
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* 30 19 * * 1,3,5 /etc/backup /dev/fd1 #Mon, Wed, Fri at 1930
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* 0 9 25 12 * /usr/bin/sing >/dev/tty0 #Xmas morning at 0900 only
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*
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* Version 1.6 SrT 90/04/08
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* Added casting fixes by Ralf Wenk, and integrated net
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* changes that release current directory, and use the
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* 1.5.5 include files. Altered assign, so no temporary
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* buffer is needed.
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*
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* Version 1.5 SrT 89/04/10
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* Changed sleep code, to type SRS sent me.
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*
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* Version 1.4 SrT 89/03/17
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* Fixed a pointer problem, when reloading crontab.
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*
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* Version 1.3 SrT 89/03/16
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* Loads crontab, into memory and only rereads the disk
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* version if it changes. (Free up those clock cycles!)
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*
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* Fixed 03/10/89, by Simmule Turner, simmy@nu.cs.fsu.edu
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* Now correctly cleans up zombie processes
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* Logs actions to /usr/adm/cronlog
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* Syncs with clock after each minute
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* Comments allowed in crontab
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* Fixed bug that prevented month, from matching
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <signal.h>
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#include <time.h>
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#include <string.h>
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#include <fcntl.h>
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#include <stdio.h>
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#ifndef DEBUG
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#define CRONTAB "/usr/lib/crontab"
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#define LOGFILE "/usr/adm/cronlog"
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#else
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#define LOGFILE "/usr/adm/cronlog.dbg"
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#define CRONTAB "/usr/adm/crontab.dbg"
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#endif
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#define NULLDEV "/dev/null"
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#define SEPARATOR " \t"
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#define CRONSIZE 2048
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#define CRONSTRUCT struct cron_entry
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#define TRUE 1
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#define FALSE 0
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struct cron_entry {
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char *mn;
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char *hr;
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char *day;
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char *mon;
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char *wkd;
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char *cmd;
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struct cron_entry *next;
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} *head, *entry_ptr;
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char crontab[CRONSIZE];
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FILE *cronlog;
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int wakeup(), ret();
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time_t previous_time = 0L;
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main()
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{
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int status;
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time_t clock;
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status = fork();
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if (status == -1) {
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fprintf(stderr, "Can't fork cron\n");
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exit(1);
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}
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if (status > 0) exit(0);
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signal(SIGINT, SIG_IGN);
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signal(SIGHUP, SIG_IGN);
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signal(SIGQUIT, SIG_IGN);
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close(0);
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close(1);
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close(2);
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chdir("/");
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open(NULLDEV, O_RDONLY);
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if ((cronlog = fopen(LOGFILE, "a")) == (FILE *) NULL) {
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open(NULLDEV, O_WRONLY);
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open(NULLDEV, O_WRONLY);
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} else {
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setbuf(cronlog, (char *) NULL);
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dup(fileno(cronlog));
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}
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entry_ptr = (CRONSTRUCT *) malloc(sizeof(CRONSTRUCT));
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entry_ptr->next = (CRONSTRUCT *) NULL;
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head = entry_ptr;
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while (TRUE) {
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signal(SIGALRM, wakeup);
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time(&clock);
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alarm((unsigned) (60 - clock % 60));
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pause();
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signal(SIGALRM, ret);
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alarm(1);
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while (wait((int *) NULL) != (-1));
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}
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}
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int ret() {}
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wakeup()
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{
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register struct tm *tm;
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time_t cur_time;
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CRONSTRUCT *this_entry = head;
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load_crontab();
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time(&cur_time);
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tm = localtime(&cur_time);
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while (this_entry->next && this_entry->mn) {
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if (match(this_entry->mn, tm->tm_min) &&
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match(this_entry->hr, tm->tm_hour) &&
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match(this_entry->day, tm->tm_mday) &&
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match(this_entry->mon, tm->tm_mon + 1) &&
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match(this_entry->wkd, tm->tm_wday)) {
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fprintf(cronlog, "%02d/%02d-%02d:%02d %s\n",
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tm->tm_mon + 1, tm->tm_mday, tm->tm_hour,
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tm->tm_min, this_entry->cmd);
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if (fork() == 0) {
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execl("/bin/sh", "/bin/sh", "-c",
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this_entry->cmd, (char *) 0);
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exit(1);
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}
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}
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this_entry = this_entry->next;
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}
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}
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/*
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* This routine will match the left string with the right number.
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*
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* The string can contain the following syntax *
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* * This will return TRUE for any number
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* x,y [,z, ...] This will return TRUE for any number given.
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* x-y This will return TRUE for any number within
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* the range of x thru y.
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*/
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match(left, right)
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register char *left;
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register int right;
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{
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register int n;
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register char c;
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n = 0;
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if (!strcmp(left, "*")) return(TRUE);
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while ((c = *left++) && (c >= '0') && (c <= '9')) n = (n * 10) + c - '0';
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switch (c) {
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case '\0':
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return(right == n);
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case ',':
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if (right == n) return(TRUE);
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do {
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n = 0;
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while ((c = *left++) && (c >= '0') && (c <= '9'))
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n = (n * 10) + c - '0';
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if (right == n) return(TRUE);
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} while (c == ',');
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return(FALSE);
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case '-':
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if (right < n) return(FALSE);
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n = 0;
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while ((c = *left++) && (c >= '0') && (c <= '9'))
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n = (n * 10) + c - '0';
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return(right <= n);
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}
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}
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load_crontab()
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{
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int pos = 0;
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FILE *cfp;
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struct stat buf;
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if (stat(CRONTAB, &buf)) {
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if (previous_time == 0L) printf("Can't stat crontab\n");
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previous_time = 0L;
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return;
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}
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#ifdef DEBUG
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printf("Crontab Time:%ld In_Core:%ld\n", buf.st_mtime, previous_time);
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#endif
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if (buf.st_mtime <= previous_time) return;
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if ((cfp = fopen(CRONTAB, "r")) == (FILE *) NULL) {
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if (previous_time == 0L) printf("Can't open crontab\n");
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previous_time = 0L;
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return;
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}
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previous_time = buf.st_mtime;
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entry_ptr = head;
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while (fgets(&crontab[pos], CRONSIZE - pos, cfp) != (char *) NULL) {
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int len;
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if (crontab[pos] == '#') continue;
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len = strlen(&crontab[pos]);
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if (crontab[pos + len - 1] == '\n') {
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len--;
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crontab[pos + len] = '\0';
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}
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assign(entry_ptr, &crontab[pos]);
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if (entry_ptr->next == (CRONSTRUCT *) NULL) {
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entry_ptr->next = (CRONSTRUCT *) malloc(sizeof(CRONSTRUCT));
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entry_ptr->next->next = (CRONSTRUCT *) NULL;
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}
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entry_ptr = entry_ptr->next;
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pos += ++len;
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if (pos >= CRONSIZE) break;
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}
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fclose(cfp);
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while (entry_ptr) {
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entry_ptr->mn = (char *) NULL;
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entry_ptr = entry_ptr->next;
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}
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#ifdef DEBUG
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printf("Crontab uses %d/%d bytes\n", pos, CRONSIZE);
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{
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CRONSTRUCT *start = head;
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dumptable(start);
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}
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#endif
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}
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assign(entry, line)
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CRONSTRUCT *entry;
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char *line;
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{
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entry->mn = strtok(line, SEPARATOR);
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entry->hr = strtok((char *) NULL, SEPARATOR);
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entry->day = strtok((char *) NULL, SEPARATOR);
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entry->mon = strtok((char *) NULL, SEPARATOR);
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entry->wkd = strtok((char *) NULL, SEPARATOR);
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entry->cmd = strchr(entry->wkd,'\0') + 1;
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}
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#ifdef DEBUG
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dumptable(table)
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CRONSTRUCT *table;
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{
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time_t clock;
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time(&clock);
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printf("\nContents of crontab at: %s", ctime(&clock));
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printf("Minute\tHour\tDay\tMonth\tWeekday\tCommand\n");
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while (table->next && table->mn) {
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printf("%s\t%s\t%s\t%s\t%s\t%s\n",
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table->mn, table->hr, table->day, table->mon,
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table->wkd, table->cmd);
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table = table->next;
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}
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}
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#endif
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