'at' bugs

[don at hscfvax.UUCP]

Subject: two bugs in at
Index:	usr.bin/at 4.2BSD

Description:
	(1)  at's date algorithm is wrong .07% of the time: it thinks the julian
	     date of March 1st in leap years is 60, not 61 (it screwed up
	     our accounting last month)
	(2)  if you try to queue more than 100 jobs at a single time, it loops
	     (patiently looking for an unused 2-digit sequence)
Repeat-By:
	(1)  unless you lie to Unix about today's date you'll have to wait
	     four years
	(2)  just try it
Fix:
19a20,21
> #define MAXJOBS 20	/* max no. of jobs queued in a particular minute */
> 
282a285,286
> 		if (detail->tm_year%4==0 && found > 1)
> 			uday += 1;		
285,286d288
< 		if (detail->tm_year%4==0 && uday>59)
< 			uday += 1;
336,341c338,357
< 	for (i=0; ; i += 53) {
< 		sprintf(fname, "%s/%02d.%03d.%04d.%02d", dir, y, d, t,
< 		   (getpid()+i)%100);
< 		if (access(fname, 0) == -1)
< 			return;
< 	}
---
> 	for(;;){
> 		for (i = 0; i < MAXJOBS; i++) {
> 			sprintf(fname, "%s/%02d.%03d.%04d.%02d", dir, y, d, t, i);
> 			if (access(fname, 0) == -1)
> 				return;
> 		}
> 
> 		/* come here if there are > MAXJOBS requests for the same time: 
> 		** move to the next minute */
> 
> 		if(++t < 2400)
> 			continue;
> 		t = 0;
> 		if(++d <= 365 + (y%4 == 0))	/* or day, if necessary */
> 			continue;
> 		d = 0;
> 		if(++y < 100)			/* or year */
> 			continue;
> 		y = 0;				/* or century */
> 		}