Re: git-2.13.0: log --date=format:%z not working

From

Ævar Arnfjörð Bjarmason <avarab@gmail.com>

Date

May 27, 2017, 16:57 UTC

Message-ID

<CACBZZX6t0Q9AJ4cpnG298tf5Las-YpmvvJXgLNNYMszikLvtMQ@mail.gmail.com>

In-Reply-To

<22824.29946.305300.380299@a1i15.kph.uni-mainz.de>

On Fri, May 26, 2017 at 8:33 PM, Ulrich Mueller <ulm@gentoo.org> wrote:

> The following commands work as expected (using commit b06d364310
> in the git://git.kernel.org/pub/scm/git/git.git repo as test case):
>
> $ export TZ=Europe/Berlin
> $ git --no-pager log -1 --pretty="%ad" --date=iso b06d364310
> 2017-05-09 23:26:02 +0900
> $ git --no-pager log -1 --pretty="%ad" --date=iso-local b06d364310
> 2017-05-09 16:26:02 +0200
>
> However, if I use explicit format: then the output of the time zone is
> wrong:
>
> $ git --no-pager log -1 --pretty="%ad" --date="format:%F %T %z" b06d364310
> 2017-05-09 23:26:02 +0000
> $ git --no-pager log -1 --pretty="%ad" --date="format-local:%F %T %z" b06d364310
> 2017-05-09 16:26:02 +0000
>
> I would expect the output to be the same as in the first two examples.

diff --git a/date.c b/date.c
index 63fa99685e..469306ebf5 100644
--- a/date.c
+++ b/date.c
@@ -70,6 +70,12 @@ static struct tm *time_to_tm(timestamp_t time, int tz)
        return gmtime(&t);
 }

+static struct tm *time_to_local_tm(timestamp_t time, int tz)
+{
+       time_t t = gm_time_t(time, tz);
+       return localtime(&t);
+}
+
 /*
  * What value of "tz" was in effect back then at "time" in the
  * local timezone?
@@ -214,10 +220,14 @@ const char *show_date(timestamp_t time, int tz,
const struct date_mode *mode)
                return timebuf.buf;
        }

-       tm = time_to_tm(time, tz);
-       if (!tm) {
-               tm = time_to_tm(0, 0);
-               tz = 0;
+       if (mode->type == DATE_STRFTIME) {
+               tm = time_to_local_tm(time, tz);
+       } else {
+               tm = time_to_tm(time, tz);
+               if (!tm) {
+                       tm = time_to_tm(0, 0);
+                       tz = 0;
+               }
         }

        strbuf_reset(&timebuf);

There's another test which breaks if we just s/gmtime/localtime/g. As
far as I can tell to make the non-local case work we'd need to do a
whole dance where we set the TZ variable to e.g. UTC$offset, then call
strftime(), then call it again. Maybe there's some way to just specify
the tz offset, but I didn't find any in a quick skimming of time.h.