diffs for ctime.c for new DST rules, v7 systems

[David Sherman]

(Note: this is cross-posted to several groups to increase its
chances of being seen by those who will want it. Followups are
directed to comp.bugs.misc.)

Both the U.S. and Canada (well, Ontario and at least some of the
other provinces) are adopting the new daylight savings time rules,
switching to DST the first Sunday in April instead of the last,
beginning in 1987.  Below is a diff for /usr/src/libc/gen/ctime.c
for v7 systems; if you're running v7 you should be able to feed
this article right into "patch".

Once you make the change to ctime.c, anything which calls
ctime(3), localtime(3) or getdate(3) should be recompiled.
I've gone through the source on our system, and found all
the commands that call these routines.
To be absolutely correct for the future, all of these should be
recompiled after the ctime change is installed.  Some of the
requirements are pretty minor, however; things like adb and awk
use ctime for diagnotic purposes only, I believe.

Here are the commands I'll be changing.  This is under Perkin-Elmer
Edition VII Workbench.  Other systems will differ; grep for
getdate, localtime and cdate through your source files.

/usr/src/cmd (basic v7 stuff):
make adb tp xsend spool/lpd awk learn uucp/* tar refer mail
ac at atrun calendar cron date ar find info iostat login ls
pr prof sa who write

/usr/src/ucb (stuff which came from Berkeley):
ex/exrecover snake daytime tod finger script ucbmail

/usr/sys/cmd (v7 and Berkeley stuff which is hardware-specific):
dmesg dump dumpdir fsck restor restor512 w

/usr/src/local (stuff off the net, etc.):
clock hdate logacct type whopast notes diff cpio news month
dumpdates last lastdown lastlog logcount lu talloc msgs

Now, to the ctime.c diffs:

The changed file will have #define NorthAm but not USA, which is
correct for Canada. If you are in the USA, add #define USA as well.
(The 1974-75 change didn't apply in Canada.)

(I also put in a minor speedup posted to the net a while back;
the test of year==74||year==75 is changed to year<=75&&year>=74,
which it a bit faster for dates between 1975 and 1987.)

Thanks to Mark Brader, {lsuc,sq}!msb, for the DST changes.
*** ctime.c.old	Thu Mar  6 19:58:52 1986
--- ctime.c	Sat Feb  7 21:13:55 1987
***************
*** 1,4
! #define	USA
  /*
  #define	Australia
  */

--- 1,4 -----
! #define	NorthAm	/* North America */
  /*
  #define	USA
  #define	Australia
***************
*** 1,5
  #define	USA
  /*
  #define	Australia
  */
  

--- 1,6 -----
  #define	NorthAm	/* North America */
  /*
+ #define	USA
  #define	Australia
  */
  
***************
*** 26,31
   *
   * The routine calls the system to determine the local
   * timezone and whether Daylight Saving Time is permitted locally.
  #ifdef	USA
   * (DST is then determined by the current US standard rules)
   * There is a table that accounts for the peculiarities

--- 27,34 -----
   *
   * The routine calls the system to determine the local
   * timezone and whether Daylight Saving Time is permitted locally.
+ #ifdef	NorthAm
+  * (DST is then determined by the current US and Canadian standard rules)
  #ifdef	USA
   * There is a table that accounts for the peculiarities
   * undergone by daylight time in 1974-1975.
***************
*** 27,33
   * The routine calls the system to determine the local
   * timezone and whether Daylight Saving Time is permitted locally.
  #ifdef	USA
-  * (DST is then determined by the current US standard rules)
   * There is a table that accounts for the peculiarities
   * undergone by daylight time in 1974-1975.
  #endif

--- 30,35 -----
  #ifdef	NorthAm
   * (DST is then determined by the current US and Canadian standard rules)
  #ifdef	USA
   * There is a table that accounts for the peculiarities
   * undergone by daylight time in 1974-1975.
  #endif
***************
*** 31,36
   * There is a table that accounts for the peculiarities
   * undergone by daylight time in 1974-1975.
  #endif
  #ifdef	Australia
   * (DST is then determined according to the Summer Time Act 1973 (Vic))
  #endif

--- 33,39 -----
   * There is a table that accounts for the peculiarities
   * undergone by daylight time in 1974-1975.
  #endif
+ #endif
  #ifdef	Australia
   * (DST is then determined according to the Summer Time Act 1973 (Vic))
  #endif
***************
*** 61,67
  #define	DS_GAP	1	/* DS time difference is 1 hour */
  
  #endif
! #ifdef	USA
  	/*
  	 * daylight saving rules (copied from Bell original)
  	 */

--- 64,70 -----
  #define	DS_GAP	1	/* DS time difference is 1 hour */
  
  #endif
! #ifdef	NorthAm
  	/*
  	 * daylight saving rules (copied from Bell original)
  	 */
***************
*** 66,72
  	 * daylight saving rules (copied from Bell original)
  	 */
  #define	HEMI	&&	/* northern hemisphere */
! #define	DS_BEGIN 119	/* last possible start for DS, (last day in Apr) */
  #define	DS_END	303	/* last possible end day for DS, (last day in Oct) */
  #define	HOUR_ON	2	/* 2am - 3am is lost when DS starts */
  #define	HOUR_OFF 1	/* 1am - 2am runs twice when DS ends (??) */

--- 69,77 -----
  	 * daylight saving rules (copied from Bell original)
  	 */
  #define	HEMI	&&	/* northern hemisphere */
! #define	DS_BEGIN 119	/* old last possible start for DS, (last day in Apr) */
! #define	DS_NBEGIN 96	/* new last possible start for DS, (Apr 7) */
! 			/* (new rule begins in 1987) */
  #define	DS_END	303	/* last possible end day for DS, (last day in Oct) */
  #define	HOUR_ON	2	/* 2am - 3am is lost when DS starts */
  #define	HOUR_OFF 1	/* 1am - 2am runs twice when DS ends (??) */
***************
*** 140,145
  	dayno = ct->tm_yday;
  	daylbegin = DS_BEGIN;
  	daylend = DS_END;
  #ifdef	USA
  	if (ct->tm_year==74 || ct->tm_year==75) {
  		daylbegin = daytab[ct->tm_year-74].daylb;

--- 145,152 -----
  	dayno = ct->tm_yday;
  	daylbegin = DS_BEGIN;
  	daylend = DS_END;
+ #ifdef	NorthAm
+ 	if (ct->tm_year >= 87) daylbegin = DS_NBEGIN;
  #ifdef	USA
  	else if (ct->tm_year<=75 && ct->tm_year>=74) {
  		daylbegin = daytab[ct->tm_year-74].daylb;
***************
*** 141,147
  	daylbegin = DS_BEGIN;
  	daylend = DS_END;
  #ifdef	USA
! 	if (ct->tm_year==74 || ct->tm_year==75) {
  		daylbegin = daytab[ct->tm_year-74].daylb;
  		daylend = daytab[ct->tm_year-74].dayle;
  	}

--- 148,154 -----
  #ifdef	NorthAm
  	if (ct->tm_year >= 87) daylbegin = DS_NBEGIN;
  #ifdef	USA
! 	else if (ct->tm_year<=75 && ct->tm_year>=74) {
  		daylbegin = daytab[ct->tm_year-74].daylb;
  		daylend = daytab[ct->tm_year-74].dayle;
  	}
***************
*** 145,150
  		daylbegin = daytab[ct->tm_year-74].daylb;
  		daylend = daytab[ct->tm_year-74].dayle;
  	}
  #endif
  	daylbegin = sunday(ct, daylbegin);
  	daylend = sunday(ct, daylend);

--- 152,158 -----
  		daylbegin = daytab[ct->tm_year-74].daylb;
  		daylend = daytab[ct->tm_year-74].dayle;
  	}
+ #endif
  #endif
  	daylbegin = sunday(ct, daylbegin);
  	daylend = sunday(ct, daylend);

David Sherman
The Law Society of Upper Canada
Toronto
-- 
{ seismo!mnetor  cbosgd!utcs  watmath  decvax!utcsri  ihnp4!utzoo  } !lsuc!dave