Re: flexfax: FW: WARNING! Hylafax Y2K bug found

[Robert Colquhoun <rjc@trump.net.au>]

Hi Ken,

At 10:21 AM 5/14/99 -0500, Ken Cornetet wrote:
>I tried sending this a couple of days ago, but I'm not sure it hit the list.
>I've checked www.hylafax.org and my note wasn't in the archive. Also, the
>web page still claims there are no Y2K issues known.

Much thanks for finding this problem, i have attached a patch which also
should fix the problem but slightly differently.  To make the whole thing a
bit more type safe so that it will be harder to make the same or the
reverse error in future.

If i have not made any stupid mistakes in the patch(someone please test!) i
will commit it and update the web page.

>I'd like to take this oportunity to ask that SOMEONE take all of the known
>patches (obviously including this Y2K patch) and roll them into the main
>release, perhaps calling it 4.1 or maybe even 4.0PL3.

Ummm, there is already a beta release on hylafax.org under the main source
code directory.  As soon as possible i will release an update with this patch.

PS This is almost a classic case why you should never use #defines in C++
unless absolutely necesary, much better to use a typesafe inline member
function.

- Robert
Index: AtSyntax.c++
===================================================================
RCS file: /usr/local/cvsroot/hylafax/util/AtSyntax.c++,v
retrieving revision 1.1.1.1
diff -c -r1.1.1.1 AtSyntax.c++
*** AtSyntax.c++	1998/10/12 20:47:48	1.1.1.1
--- AtSyntax.c++	1999/05/15 06:54:02
***************
*** 38,44 ****
  #define HALFDAY		(12 * HOUR)	// half a day (12 hours)
  #define FULLDAY		(24 * HOUR)	// a full day (24 hours)
  
! #define	isLeapYear(y)	(((y) % 4) == 0 && ((y) % 100) != 0 || ((y) % 400) == 0)
  
  #ifdef streq
  #undef streq
--- 38,48 ----
  #define HALFDAY		(12 * HOUR)	// half a day (12 hours)
  #define FULLDAY		(24 * HOUR)	// a full day (24 hours)
  
! static int
! isLeapYear(const tm& at) {
!     int y = at.tm_year + TM_YEAR_BASE;
!     return ((y % 4) == 0 && (y % 100) != 0 || (y % 400) == 0);
! }
  
  #ifdef streq
  #undef streq
***************
*** 295,301 ****
  adjustYDay(struct tm& t)
  {
      // adjust year day according to month
!     const u_int* days = daysInMonth[isLeapYear(t.tm_year)];
      t.tm_yday = t.tm_mday;
      for (u_int i = 0; i < t.tm_mon; i++)
  	t.tm_yday += days[i];
--- 299,305 ----
  adjustYDay(struct tm& t)
  {
      // adjust year day according to month
!     const u_int* days = daysInMonth[isLeapYear(t)];
      t.tm_yday = t.tm_mday;
      for (u_int i = 0; i < t.tm_mon; i++)
  	t.tm_yday += days[i];
***************
*** 344,350 ****
  	    adjustYDay(at);
  	}
      }
!     const u_int* days = daysInMonth[isLeapYear(at.tm_year)];
      if (at.tm_mday > days[at.tm_mon]) {
  	_atError(emsg, "Invalid day of month, %s has only %u days",
  	    months[at.tm_mon], days[at.tm_mon]);
--- 348,354 ----
  	    adjustYDay(at);
  	}
      }
!     const u_int* days = daysInMonth[isLeapYear(at)];
      if (at.tm_mday > days[at.tm_mon]) {
  	_atError(emsg, "Invalid day of month, %s has only %u days",
  	    months[at.tm_mon], days[at.tm_mon]);
***************
*** 412,418 ****
      fxBool leap;
      int daysinyear;
      for (;;) {
! 	leap = isLeapYear(at.tm_year);
  	daysinyear = leap ? 366 : 365;
  	if (at.tm_yday < daysinyear)
  	    break;
--- 416,422 ----
      fxBool leap;
      int daysinyear;
      for (;;) {
! 	leap = isLeapYear(at);
  	daysinyear = leap ? 366 : 365;
  	if (at.tm_yday < daysinyear)
  	    break;
***************
*** 429,436 ****
      at.tm_mday++;			// NB: [1..31]
  
      int eday = at.tm_yday;
!     for (u_int year = EPOCH_YEAR - TM_YEAR_BASE; year < at.tm_year; year++)
! 	eday += isLeapYear(year) ? 366 : 365;
      at.tm_wday = (EPOCH_WDAY + eday) % DAYSPERWEEK;
  }
  
--- 433,444 ----
      at.tm_mday++;			// NB: [1..31]
  
      int eday = at.tm_yday;
!     tm temp;
!     temp.tm_year = EPOCH_YEAR - TM_YEAR_BASE;
!     while (temp.tm_year < at.tm_year) {
!         eday += isLeapYear(temp) ? 366 : 365;
!         temp.tm_year++;
!     }
      at.tm_wday = (EPOCH_WDAY + eday) % DAYSPERWEEK;
  }