Ben Walton writes:
> When passed a local time that was on the boundary of a DST change,
> get_tz_offset returned a GMT offset that was incorrect (off by one
> hour). This is because the time was converted to GMT and then back to
> a time stamp via timelocal() which cannot disambiguate boundary cases
> as noted in its documentation.
>
> Modify this algorithm, using an approach suggested by Junio C Hamano
> that obtains the GMT time stamp by using timegm(localtime()) instead
> of timelocal(gmtime()). This avoids the ambigious conversion and
> allows a correct time to be returned on every occassion.
I'll reword the log message a bit to explain why the updated logic
is right and also refer to the message that has the suggestion. o
The implemmentation is a bit dense to my taste, but looks correct (I
had to think about the comparison to come up with the value of the
$sign, though).
Thanks.
> Signed-off-by: Ben Walton
> ---
> perl/Git.pm |6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/perl/Git.pm b/perl/Git.pm
> index 5649bcc..a56d1e7 100644
> --- a/perl/Git.pm
> +++ b/perl/Git.pm
> @@ -103,7 +103,7 @@ use Error qw(:try);
> use Cwd qw(abs_path cwd);
> use IPC::Open2 qw(open2);
> use Fcntl qw(SEEK_SET SEEK_CUR);
> -use Time::Local qw(timelocal);
> +use Time::Local qw(timegm);
> }
>
>
> @@ -528,8 +528,8 @@ If TIME is not supplied, the current local time is used.
> sub get_tz_offset {
> # some systmes don't handle or mishandle %z, so be creative.
> my $t = shift || time;
> - my $gm = timelocal(gmtime($t));
> - my $sign = qw( + + - )[ $t <=> $gm ];
> + my $gm = timegm(localtime($t));
> + my $sign = qw( + + - )[ $gm <=> $t ];
> return sprintf("%s%02d%02d", $sign, (gmtime(abs($t - $gm)))[2,1]);
> }
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