Re: Bug in zic.c?

Sept. 29, 2010

      That is indeed a bug--in particular, in the DOWLEQ (<=) code.
The bug wasn't triggered up to now since all the distributed rules use
DOWGEQ (>=). Below is a proposed fix (and slight simplification).

Note that the checks are needed to ensure that rules specified in the
zic input are representable by POSIX environment variables.

				--ado

------- zic.c -------
*** /tmp/geta23934	Wed Sep 29 08:45:01 2010
--- /tmp/getb23934	Wed Sep 29 08:45:01 2010
***************
*** 3,9 ****
  ** 2006-07-17 by Arthur David Olson.
  */

! static char	elsieid[] = "@(#)zic.c	8.22";

  #include "private.h"
  #include "locale.h"
--- 3,9 ----
  ** 2006-07-17 by Arthur David Olson.
  */

! static char	elsieid[] = "@(#)zic.c	8.23";

  #include "private.h"
  #include "locale.h"
***************
*** 1881,1896 ****
  		register int	week;

  		if (rp->r_dycode == DC_DOWGEQ) {
! 			week = 1 + rp->r_dayofmonth / DAYSPERWEEK;
! 			if ((week - 1) * DAYSPERWEEK + 1 != rp->r_dayofmonth)
  				return -1;
  		} else if (rp->r_dycode == DC_DOWLEQ) {
  			if (rp->r_dayofmonth == len_months[1][rp->r_month])
  				week = 5;
  			else {
! 				week = 1 + rp->r_dayofmonth / DAYSPERWEEK;
! 				if (week * DAYSPERWEEK - 1 != rp->r_dayofmonth)
  					return -1;
  			}
  		} else	return -1;	/* "cannot happen" */
  		(void) sprintf(result, "M%d.%d.%d",
--- 1881,1896 ----
  		register int	week;

  		if (rp->r_dycode == DC_DOWGEQ) {
! 			if ((rp->r_dayofmonth % DAYSPERWEEK) != 1)
  				return -1;
+ 			week = 1 + rp->r_dayofmonth / DAYSPERWEEK;
  		} else if (rp->r_dycode == DC_DOWLEQ) {
  			if (rp->r_dayofmonth == len_months[1][rp->r_month])
  				week = 5;
  			else {
! 				if ((rp->r_dayofmonth % DAYSPERWEEK) != 0)
  					return -1;
+ 				week = rp->r_dayofmonth / DAYSPERWEEK;
  			}
  		} else	return -1;	/* "cannot happen" */
  		(void) sprintf(result, "M%d.%d.%d",