Debian Bug report logs - #664959
gawk: mktime fails when date changes to daylight savings time

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: Sebastian Luque <spluque@gmail.com>

To: Debian Bug Tracking System <submit@bugs.debian.org>

Subject: gawk: mktime fails when date changes to daylight savings time

Date: Wed, 21 Mar 2012 15:47:31 -0500

Package: gawk
Version: 1:3.1.8+dfsg-0.1
Severity: normal

Dear Maintainer,

With the following program (test.awk):

---<--------------------cut here---------------start------------------->---
{print fix_time($0)}
function fix_time(tstr) {     # tstr=time string field
    if (length(tstr) != 21 || !tstr) {
	return tstr
    } else {
	Y=substr(tstr, 2, 4)
	M=substr(tstr, 7, 2)
	D=substr(tstr, 10, 2)
	h=substr(tstr, 13, 2)
	m=substr(tstr, 16, 2)
	s=substr(tstr, 19, 2)
	t=mktime(sprintf("%s %s %s %s %s %s", Y, M, D, h, m, s))
	return strftime("%Y-%m-%d %H:%M:%S", t)
    }
}
---<--------------------cut here---------------end--------------------->---

$ echo '"2012-03-11 01:00:00"' | gawk -f test.awk
2012-03-11 01:00:00
$ echo '"2012-03-11 02:00:00"' | gawk -f test.awk
2012-03-11 03:00:00
$ echo '"2012-03-11 03:00:00"' | gawk -f test.awk
2012-03-11 03:00:00
$ echo '"2012-03-11 04:00:00"' | gawk -f test.awk
2012-03-11 04:00:00

$ echo '"2012-03-12 01:00:00"' | gawk -f test.awk
2012-03-12 01:00:00
$ echo '"2012-03-12 02:00:00"' | gawk -f test.awk
2012-03-12 02:00:00
$ echo '"2012-03-12 03:00:00"' | gawk -f test.awk
2012-03-12 03:00:00

Daylight savings for my local time zone (Central Time) started on
2012-03-11.  Time is not interpreted correctly for the second hour of
the day when daylight savings starts.


-- System Information:
Debian Release: wheezy/sid
  APT prefers unstable
  APT policy: (990, 'unstable'), (500, 'testing-proposed-updates'), (500, 'testing'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 3.2.0-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_CA.UTF-8, LC_CTYPE=en_CA.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages gawk depends on:
ii  libc6        2.13-27
ii  libsigsegv2  2.9-4

gawk recommends no packages.

gawk suggests no packages.

-- no debconf information


-- 
Seb

Message #8 received at 664959@bugs.debian.org (full text, mbox, reply):

From: Bob Proulx <bob@proulx.com>

To: Sebastian Luque <spluque@gmail.com>, 664959@bugs.debian.org

Subject: Re: Bug#664959: gawk: mktime fails when date changes to daylight savings time

Date: Wed, 21 Mar 2012 15:40:21 -0600

Sebastian Luque wrote:
> $ echo '"2012-03-11 02:00:00"' | gawk -f test.awk
> 2012-03-11 03:00:00
> ...
> Daylight savings for my local time zone (Central Time) started on
> 2012-03-11.  Time is not interpreted correctly for the second hour of
> the day when daylight savings starts.

Please state your canonical timezone?  Central Time by itself is
ambiguous.  But I can guess.

Note that 2012-03-11 02:00:00 is an invalid date in Central time.
There is no correct interpretation possible.  Or perhaps the only
correct interpretation would be to throw an exception error.

  $ TZ=US/Central date -R -d '2012-03-11 02:00:00'
  date: invalid date `2012-03-11 02:00:00'

What should awk do with invalid dates?  Should it report them as
invalid as gnu date does?  Probably.

See this useful reference for coreutils date.  (Of course I am biased
about its usefulness. :-)

  http://www.gnu.org/software/coreutils/faq/#The-date-command-is-not-working-right_002e

Bob

Message #13 received at 664959@bugs.debian.org (full text, mbox, reply):

From: Sebastian P. Luque <spluque@gmail.com>

To: Bob Proulx <bob@proulx.com>

Cc: 664959@bugs.debian.org

Subject: Re: Bug#664959: gawk: mktime fails when date changes to daylight savings time

Date: Wed, 21 Mar 2012 22:12:34 -0500

On Wed, 21 Mar 2012 15:40:21 -0600,
Bob Proulx <bob@proulx.com> wrote:

> Sebastian Luque wrote:
>> $ echo '"2012-03-11 02:00:00"' | gawk -f test.awk 2012-03-11 03:00:00
>> ...  Daylight savings for my local time zone (Central Time) started
>> on 2012-03-11.  Time is not interpreted correctly for the second hour
>> of the day when daylight savings starts.

> Please state your canonical timezone?  Central Time by itself is
> ambiguous.  But I can guess.

> Note that 2012-03-11 02:00:00 is an invalid date in Central time.
> There is no correct interpretation possible.  Or perhaps the only
> correct interpretation would be to throw an exception error.

>   $ TZ=US/Central date -R -d '2012-03-11 02:00:00' date: invalid date
> `2012-03-11 02:00:00'

> What should awk do with invalid dates?  Should it report them as
> invalid as gnu date does?  Probably.

> See this useful reference for coreutils date.  (Of course I am biased
> about its usefulness. :-)

>   http://www.gnu.org/software/coreutils/faq/#The-date-command-is-not-working-right_002e

Yes, I totally agree.  We were discussing this in the awk newsgroup
(http://groups.google.com/group/comp.lang.awk/browse_thread/thread/1e77bcbb851fd4ea#).


-- 
Seb

Message #18 received at 664959-done@bugs.debian.org (full text, mbox, reply):

From: Jeroen Schot <schot@A-Eskwadraat.nl>

To: 664959-done@bugs.debian.org

Subject: Re: gawk: mktime fails when date changes to daylight savings time

Date: Thu, 5 Apr 2012 15:59:21 +0200

Version: 1:3.1.8+dfsg-0.1


Hello,

Thanks for your bug report. While the current behavior is surprising,
there is nothing gawk can do about it. The mktime functions is simply
a wrapper around the C/POSIX function with the same name and by design
has the same semantics. This function even explicitly allows out of
range values, as documented in the gawk man page. In comp.lang.awk I
see Geoff Clare reaching the same conclusion. 

Regards,

Jeroen Schot

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