fix POSIX-format TZ dst transition times for southern hemisphere

the time of day at which daylight time switches over is specified in
local time in the dst state prior to the transition. the code for
handling this wrongly assumed it needed to switch whether dst or
standard offset is applied to the transition time when the dst end
date is before the dst start date (souther hemisphere summer), but in
fact the end transition time should always be adjusted for dst, and
the start transition time should always be adjusted for standard time.

diff --git a/src/time/__tz.c b/src/time/__tz.c
index 0e0c4ea240f0179d3abe491406f38b75223f4a30..ffe8d4020d5ac12d54b87586f7c32e599a124fe0 100644 (file)
--- a/src/time/__tz.c
+++ b/src/time/__tz.c
@@ -373,18 +373,14 @@ void __secs_to_zone(long long t, int local, int *isdst, long *offset, long *oppo
        long long t0 = rule_to_secs(r0, y);
        long long t1 = rule_to_secs(r1, y);
 
+       if (!local) {
+               t0 += __timezone;
+               t1 += dst_off;
+       }
        if (t0 < t1) {
-               if (!local) {
-                       t0 += __timezone;
-                       t1 += dst_off;
-               }
                if (t >= t0 && t < t1) goto dst;
                goto std;
        } else {
-               if (!local) {
-                       t1 += __timezone;
-                       t0 += dst_off;
-               }
                if (t >= t1 && t < t0) goto std;
                goto dst;
        }