[9fans] dst shift is shifty

[lyndon@orthanc.ca (Lyndon Nerenberg (VE6BBM/VE7TFX))]

> i tried to send this off-list, but your zone has no mx record.
> sorry to the rest of the list for spam.

And I tried a direct reply, but your MTA is convinced orthanc.ca has
no MX record.  Which is odd since it most most certainly does.  I've
noticed ndb/dns has been acting oddly lately, though.  For the last
couple of months my CPU server has been complaining that
ftp.rfc-editor.org has a malformed IP address while my terminal has no
issue with it.  It hasn't been annoying enough to track down since I
have a workaround, but something weirde is going on here ...

> anyway, lyndon could you check the timezones in
> /n/sources/contrib/quanstro/timezone/tz/Canada_*
> to make sure i haven't made any silly mistakes?

Attached is a trivial timezone file dumper I wrote this morning before
the benefit of coffee.  When I examine the output of runs against
*_Pacific (the system's and Eric's new Canada_*) it strikes me that
the time shifts are happening at UTC time rather than the local
timezone offset.  E.g., here is a sample of
/adm/timezone/Canada_Pacific:

                         PST	                         PDT
Sun Apr 26 02:00:00 GMT 1970	Sun Oct 25 01:00:00 GMT 1970
Sun Apr 25 02:00:00 GMT 1971	Sun Oct 31 01:00:00 GMT 1971
Sun Apr 30 02:00:00 GMT 1972	Sun Oct 29 01:00:00 GMT 1972
Sun Apr 29 02:00:00 GMT 1973	Sun Oct 28 01:00:00 GMT 1973
Sun Apr 28 02:00:00 GMT 1974	Sun Oct 27 01:00:00 GMT 1974

Should these not be taking place either seven or eight hours later
according to GMT?  (I.e.  0200 PST, 0200 PDT) Am I misinterpreting the
values in the timezone files?

--lyndon

-------------- next part --------------
#include <u.h>
#include <libc.h>
#include <stdio.h>

struct tz {
	int offset;
	char zone[5];
};

static char EPARSE[] = "parse error";

void main (int argc, char **argv)
{
	struct tz tz[2];
	Tm *t;
	long i[2];
	int rc;
	char *s;
	
	rc = scanf("%s %d %s %d", &tz[0].zone, &tz[0].offset,
				&tz[1].zone, &tz[1].offset);
	if (rc == EOF || rc != 4) {
		exits(EPARSE);
	}
	printf("%28s\t%28s\n", tz[0].zone, tz[1].zone);
	for (;;) {
		rc = scanf("%ld %ld", &i[0], &i[1]);
		if (rc == EOF) {
			exits(0);
		}
		if (rc != 2) {
			exits(EPARSE);
		}
		t = gmtime(i[0]);
		s = asctime(t);
		s[28] = '\0';
		printf("%s\t", s);
		t = gmtime(i[1]);
		s = asctime(t);
		s[28] = '\0';
		printf("%s\n", s);
	}
	exits(0);
}