search: fix rt: w/ approxidate when TZ != UTC

While git respects a user's local timezone and returns
seconds-since-the-Epoch, we were unnecessarily and incorrectly
calling gmtime+strftime on its result.  So ignore calling
gmtime+strftime when the strftime format is "%s", just feed
the output time from git directly to Xapian.

This is mainly for lei, which will likely run in a variety of
timezones.  While we're at it, add a recommendation to use
TZ=UTC in public-inbox-httpd, in case there are (misguided :P)
sysadmins who set a non-UTC TZ.

1 files changed, 7 insertions, 4 deletions

diff --git a/lib/PublicInbox/Search.pm b/lib/PublicInbox/Search.pm
index e80a5944..af0a35d9 100644
--- a/lib/PublicInbox/Search.pm
+++ b/lib/PublicInbox/Search.pm
@@ -332,7 +332,7 @@ sub date_parse_prepare {
                         push @$to_parse, $x;
                         $x = "\0%s$#$to_parse\0";
                 }
-                $r[1] //= "\0%s+\0";
+                $r[1] //= "\0%s+\0"; # add 1 day
         }
         "$pfx:".join('..', @r).$end;
 }
@@ -342,9 +342,12 @@ sub date_parse_finalize {
         # git-rev-parse can handle any number of args up to system
         # limits (around (4096*32) bytes on Linux).
         my @r = $git->date_parse(@$to_parse);
-        my $i;
-        $_[2] =~ s/\0(%[%YmdHMSs]+)([0-9\+]+)\0/strftime($1,
-                gmtime($2 eq '+' ? ($r[$i]+86400) : $r[$i=$2+0]))/sge;
+        # n.b. git respects TZ, times stored in SQLite/Xapian are always UTC,
+        # and gmtime doesn't seem to do the right thing when TZ!=UTC
+        my ($i, $t);
+        $_[2] =~ s/\0(%[%YmdHMSs]+)([0-9\+]+)\0/
+                $t = $2 eq '+' ? ($r[$i]+86400) : $r[$i=$2+0];
+                $1 eq '%s' ? $t : strftime($1, gmtime($t))/sge;
 }
 
 # n.b. argv never has NUL, though we'll need to filter it out