[PATCH] git-svn: Fix time zone in --localtime

Use numerical form of time zone to replace alphabetic time zone
abbreviation generated by "%Z". "%Z" is not portable and contain
ambiguity for many areas. For example, CST could be "Central
Standard Time" (GMT-0600) and "China Standard Time" (GMT+0800).
Alphabetic time zone abbreviation is meant for human readability,
not for specifying a time zone for machines.

Failed case can be illustrated like this in linux shell:
  > echo $TZ
  Asia/Taipei
  > date +%Z
  CST
  > env TZ=`date +%Z` date
  Mon Dec 19 06:03:04 CST 2011
  > date
  Mon Dec 19 14:03:04 CST 2011

Signed-off-by: Wei-Yin Chen (陳威尹) <redacted>
---
 git-svn.perl |   18 +++++++++++-------
 1 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/git-svn.perl b/git-svn.perl
index e30df22..f0b6340 100755
--- a/git-svn.perl
+++ b/git-svn.perl

@@ -2029,6 +2029,7 @@ use Carp qw/croak/;
 use File::Path qw/mkpath/;
 use File::Copy qw/copy/;
 use IPC::Open3;
+use Time::Local;
 use Memoize;  # core since 5.8.0, Jul 2002
 use Memoize::Storable;

@@ -3287,6 +3288,14 @@ sub get_untracked {
 	\@out;
 }

+sub get_tz {
+	# 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 ];
+	return sprintf("%s%02d%02d", $sign, (gmtime(abs($t - $gm)))[2,1]);
+}
+
 # parse_svn_date(DATE)
 # --------------------
 # Given a date (in UTC) from Subversion, return a string in the format

@@ -3319,8 +3328,7 @@ sub parse_svn_date {
 			delete $ENV{TZ};
 		}

-		my $our_TZ =
-		    POSIX::strftime('%Z', $S, $M, $H, $d, $m - 1, $Y - 1900);
+		my $our_TZ = get_tz();

 		# This converts $epoch_in_UTC into our local timezone.
 		my ($sec, $min, $hour, $mday, $mon, $year,

@@ -5994,7 +6002,6 @@ package Git::SVN::Log;
 use strict;
 use warnings;
 use POSIX qw/strftime/;
-use Time::Local;
 use constant commit_log_separator => ('-' x 72) . "\n";
 use vars qw/$TZ $limit $color $pager $non_recursive $verbose $oneline
             %rusers $show_commit $incremental/;

@@ -6104,11 +6111,8 @@ sub run_pager {
 }

 sub format_svn_date {
-	# 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 $gmoff = sprintf("%s%02d%02d", $sign, (gmtime(abs($t - $gm)))[2,1]);
+	my $gmoff = get_tz($t);
 	return strftime("%Y-%m-%d %H:%M:%S $gmoff (%a, %d %b %Y)", localtime($t));
 }

"\"Wei-Yin Chen (陳威尹)\"" [off-list ref] wrote:

Use numerical form of time zone to replace alphabetic time zone
abbreviation generated by "%Z". "%Z" is not portable and contain
ambiguity for many areas. For example, CST could be "Central
Standard Time" (GMT-0600) and "China Standard Time" (GMT+0800).
Alphabetic time zone abbreviation is meant for human readability,
not for specifying a time zone for machines.

Failed case can be illustrated like this in linux shell:
  > echo $TZ
  Asia/Taipei
  > date +%Z
  CST
  > env TZ=`date +%Z` date
  Mon Dec 19 06:03:04 CST 2011
  > date
  Mon Dec 19 14:03:04 CST 2011

Signed-off-by: Wei-Yin Chen (陳威尹) <redacted>
---

Hi, sorry for the late reply, this got lost in the shuffle.

This issue seems reasonable, but did you test this change at all?

 sub format_svn_date {
-	# 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 $gmoff = sprintf("%s%02d%02d", $sign, (gmtime(abs($t - $gm)))[2,1]);
+	my $gmoff = get_tz($t);
 	return strftime("%Y-%m-%d %H:%M:%S $gmoff (%a, %d %b %Y)", localtime($t));
 }

I needed the following additional change to get things working:

--- a/git-svn.perl
+++ b/git-svn.perl

@@ -6111,7 +6111,7 @@ sub run_pager {
 
 sub format_svn_date {
 	my $t = shift || time;
-	my $gmoff = get_tz($t);
+	my $gmoff = Git::SVN::get_tz($t);
 	return strftime("%Y-%m-%d %H:%M:%S $gmoff (%a, %d %b %Y)", localtime($t));
 }

If there are no objections, I'll squash this and push for Junio
tomorrow.

On 2012-02-12 16:15, Eric Wong wrote:

Sorry, my bad. This bug of missing package reference can be triggered by 
"git svn log", but unfortunately I didn't test this part manually. I'll 
learn to use the git test suite next time.

If there are no objections, I'll squash this and push for Junio
tomorrow.

Excellent. Thank you for the testing and fixing effort!