[Gnash-dev] tzdata is wrong for epoch in Europe/London

[Martin Guy]

Package: tzdata
Version: 2006p-1

localtime() resolves time==0 as Jan 1 1970 01:00 instead of 00:00 in
the Europe/London timezone. This was in etch; it also does this in
Debian sarge and gentoo, so I guess it's an old upstream bug.

It may be a bug in localtime() but certainly depends on the named
timezone (see below).

I'm amazed no one has spotted this before!
In fact, versions of libc/zoneinfo from 2000 (libc2.1.3) behave the same.
Is there something I'm missing here?

Repeat-by:
cat >> c.c << EOF
#include <time.h>
#include <stdio.h>

extern long timezone;   /* Seconds west of gmt */

main()
{
       time_t t = 0;
       struct tm *tmp;

       printf("Epoch in gmtime is %s", asctime(gmtime(&t)));
       printf("Epoch in localtime is %s", asctime(tmp = localtime(&t)));
       printf("timezone is %ld minutes east of UTC\n", -timezone/60);
       printf("DST was%s in effect\n", tmp->tm_isdst ? "" : "n't");
}
EOF
$ cc c.c
$ TZ=Europe/London ./a,out      # Europe/London is broken.
Epoch in gmtime is Thu Jan  1 00:00:00 1970
Epoch in localtime is Thu Jan  1 01:00:00 1970
timezone is 0 minutes east of UTC
DST wasn't in effect.
$ TZ=Europe/Paris ./a.out        # Paris, on the same meridian, works ok.
Epoch in gmtime is Thu Jan  1 00:00:00 1970
Epoch in localtime is Thu Jan  1 00:00:00 1970
timezone is 0 minutes east of UTC
DST wasn't in effect
$ TZ=GMT+0 ./a.out                # Absolute timezone works ok
Epoch in gmtime is Thu Jan  1 00:00:00 1970
Epoch in localtime is Thu Jan  1 00:00:00 1970
timezone is 0 minutes east of UTC
DST wasn't in effect
$ TZ=Europe/Warsaw             # A location truly one hour out works ok
Epoch in gmtime is Thu Jan  1 00:00:00 1970
Epoch in localtime is Thu Jan  1 01:00:00 1970
timezone is 60 minutes east of UTC
DST wasn't in effect

Other named locations on the GMT+0 meridian may also be similarly broken.

   M