diff options
Diffstat (limited to 'time/mktime.c')
| -rw-r--r-- | time/mktime.c | 39 |
1 files changed, 27 insertions, 12 deletions
diff --git a/time/mktime.c b/time/mktime.c index 0fa92e0e65..6135d70bd6 100644 --- a/time/mktime.c +++ b/time/mktime.c @@ -350,29 +350,44 @@ __mktime_internal (tp, convert, offset) /* If we have a match, check whether tm.tm_isdst has the requested value, if any. */ - if (dt == 0 && 0 <= isdst && 0 <= tm.tm_isdst) + if (dt == 0 && isdst >= 0 && isdst != tm.tm_isdst) { int dst_diff = (isdst != 0) - (tm.tm_isdst != 0); if (dst_diff) { - /* Move two hours in the direction indicated by the disagreement, + /* Move three hours in the direction indicated by the disagreement, probe some more, and switch to a new time if found. The largest known fallback due to daylight savings is two hours: - once, in Newfoundland, 1988-10-30 02:00 -> 00:00. */ - time_t ot = t - 2 * 60 * 60 * dst_diff; + once, in Newfoundland, 1988-10-30 02:00 -> 00:00. + But some programs (e.g. testsuites) probe for larger differences + between DST and normal time so switch by three hours. No + normal program does this so we do not account for more than + three hours difference. */ + time_t ot = t - 3 * 60 * 60 * dst_diff; + struct tm otm; + struct tm tmptm; + + otm.tm_isdst = -1; + while (--remaining_probes != 0) { - struct tm otm; if (! (dt = ydhms_tm_diff (year, yday, hour, min, sec, - ranged_convert (convert, &ot, &otm)))) - { - t = ot; - tm = otm; - break; - } - if ((ot += dt) == t) + ranged_convert (convert, &ot, + &tmptm))) + || tmptm.tm_isdst != isdst) + break; + + otm = tmptm; + ot += dt; + if (ot == t) break; /* Avoid a redundant probe. */ } + + if (otm.tm_isdst != -1) + { + t = ot; + tm = otm; + } } } |