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[unix-history] / usr / source / s1 / cron.c

#define ANY     -1
#define LIST    -2
#define RANGE   -3
#define EOF     -4
char    *crontab        "/usr/lib/crontab";
char    *crontmp        "/tmp/crontmp";
char    *aend;
char    *itime[2];
int     *loct;
int     *localtime();
int     reset();
int     flag;

main()
{
       register i, t;
       register char *cp;
       extern char end[];

       setuid(1);
       itime[0] = fork();
       if(itime[0])
               exit();
       setexit();
       signal(1, reset);
       time(itime);
       while(*localtime(itime))
               if(itime[1]-- == 0)
                       itime[0]--;

loop:
       init();
       for(i=60; i; i--) {
               loct = localtime(itime);
               for(cp = end; *cp != EOF;) {
                       flag = 0;
                       cp = cmp(cp, loct[1]); /* minute */
                       cp = cmp(cp, loct[2]); /* hour */
                       cp = cmp(cp, loct[3]); /* day */
                       cp = cmp(cp, loct[4]); /* month */
                       cp = cmp(cp, loct[6]); /* day of week */
                       if(flag == 0) {
                               slp();
                               ex(cp);
                       }
                       while(*cp++ != 0)
                               ;
               }
               t = itime[1] + 60;
               if(t < itime[1])
                       itime[0]++;
               itime[1] = t;
       }
       slp();
       goto loop;
}

cmp(p, v)
char *p;
{
       register char *cp;

       cp = p;
       switch(*cp++) {

       case ANY:
               return(cp);

       case LIST:
               while(*cp != LIST)
                       if(*cp++ == v) {
                               while(*cp++ != LIST)
                                       ;
                               return(cp);
                       }
               flag++;
               return(cp+1);

       case RANGE:
               if(*cp > v || cp[1] < v)
                       flag++;
               return(cp+2);
       }
       if(cp[-1] != v)
               flag++;
       return(cp);
}

slp()
{
       register i;
       int     t[2];

       time(t);
       i = itime[1] - t[1];
       if(i > 0)
               sleep(i);
}

ex(s)
char *s;
{
       register i;

       if(fork()) {
               wait();
               return;
       }
       for(i=0; s[i]; i++);
       close(0);
       creat(crontmp, 0600);
       write(0, s, i);
       close(0);
       open(crontmp, 0);
       unlink(crontmp);
       if(fork())
               exit();
       execl("/bin/sh", "sh", "-t", 0);
       exit();
}

init()
{
       int ib[259], t[10];
       register i, c;
       register char *cp;
       char *ocp;
       int n;
       extern char end[];

       if(fopen(crontab, ib) < 0) {
               write(1, "cannot open table\n", 18);
               exit();
       }
       cp = end;
       if(aend == 0)
               aend = cp;

loop:
       ocp = cp;
       if(cp+100 > aend) {
               aend =+ 512;
               brk(aend);
       }
       for(i=0;; i++) {
               do
                       c = getc(ib);
               while(c == ' ' || c == '\t');
               if(c <= 0 || c == '\n')
                       goto ignore;
               if(i == 5)
                       break;
               if(c == '*') {
                       *cp++ = ANY;
                       continue;
               }
               n = 0;
               while(c >= '0' && c <= '9') {
                       n = n*10 + c-'0';
                       c = getc(ib);
               }
               if(n < 0 || n > 100)
                       goto ignore;
               if(c == ',')
                       goto list;
               if(c == '-')
                       goto range;
               if(c != '\t' && c != ' ')
                       goto ignore;
               *cp++ = n;
               continue;

       list:
               *cp++ = LIST;
               *cp++ = n;
       list1:
               n = 0;
               c = getc(ib);
               while(c >= '0' && c <= '9') {
                       n = n*10 + c-'0';
                       c = getc(ib);
               }
               if(n < 0 || n > 100)
                       goto ignore;
               *cp++ = n;
               if(c == ',')
                       goto list1;
               if(c != '\t' && c != ' ')
                       goto ignore;
               *cp++ = LIST;
               continue;

       range:
               *cp++ = RANGE;
               *cp++ = n;
               n = 0;
               c = getc(ib);
               while(c >= '0' && c <= '9') {
                       n = n*10 + c-'0';
                       c = getc(ib);
               }
               if(n < 0 || n > 100)
                       goto ignore;
               if(c != '\t' && c != ' ')
                       goto ignore;
               *cp++ = n;
       }
       while(c != '\n') {
               if(c <= 0)
                       goto ignore;
               if(c == '%')
                       c = '\n';
               *cp++ = c;
               c = getc(ib);
       }
       *cp++ = '\n';
       *cp++ = 0;
       goto loop;

ignore:
       cp = ocp;
       while(c != '\n') {
               if(c <= 0) {
                       close(ib[0]);
                       *cp++ = EOF;
                       *cp++ = EOF;
                       aend = cp;
                       brk(aend);
                       return;
               }
               c = getc(ib);
       }
       goto loop;
}