From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <1209a838da1003845b874b8a9ca0b4b7@isd.dp.ua>
To: 9fans@9fans.net
From: yaroslav <yarikos@gmail.com>
Date: Mon, 28 Sep 2009 15:33:22 +0200
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Subject: [9fans] /adm/timezone/EET is bad
Topicbox-Message-UUID: 792e8c16-ead5-11e9-9d60-3106f5b1d025

Today I noticed my Plan 9 machine displayed time which is 1 hr past
surrounding world.  Digging around, I found that DST start/end dates
for Eastern-European Time (/adm/timezone/EET) for current year are
bad.  Those follow pre-1996 conventions for ending dates and does DST
switch 2 hours later.  For more information, see
http://en.wikipedia.org/wiki/European_Summer_Time.

Bundled program prints valid pair of dates for a given year in
1996-2099 range.

Yaroslav.


# To unbundle, run this file
echo eet.c
sed 's/.//' >eet.c <<'//GO.SYSIN DD eet.c'
-/* Calculates DST start/end dates for EET timezone on a year given on
-cmdline.  {8c eet.c && 8l eet.8 && 8.out} */
-#include <u.h>
-#include <libc.h>
-
-void
-main(int argc, char* argv[])
-{
-	int yr = 2009;
-	Tm tm[] = {{
-		.sec = 0,
-		.min = 0,
-		.hour = 1,
-		.mday = 0,
-		.mon = 2,
-		.year = 0,
-		.wday = 0,
-		.zone = "GMT",
-		.tzoff = 0
-	}, {
-		.sec = 0,
-		.min = 0,
-		.hour = 1,
-		.mday = 0,
-		.mon = 9,
-		.year = 0,
-		.wday = 0,
-		.zone = "GMT",
-		.tzoff = 0
-	}};
-
-	if(argc > 1)
-		yr = atoi(argv[1]);
-
-	tm[0].year = tm[1].year = (yr - 1900);
-	tm[0].mday = (31 - (5*yr/4 + 4) % 7);
-	tm[1].mday = (31 - (5*yr/4 + 1) % 7);
-	/* formulas are valid until 2099 */
-
-	print("%d %d\n", tm2sec(&tm[0]), tm2sec(&tm[1]));
-	exits(nil);
-}
//GO.SYSIN DD eet.c