Mercurial > hg > octave-lojdl > gnulib-hg
changeset 1517:3f9b7ee1667a
(__mktime_internal): When the requested time falls
in a spring-forward gap of size DT, return a time that is DT
away from the requested time, preferring a time whose tm_isdst
differs from the requested value. Bump the max number of
probes from 4 to 6 to account for the extra probes needed to
discover a spring-forward gap in the worst case.
| author | Jim Meyering <jim@meyering.net> |
|---|---|
| date | Sun, 11 Oct 1998 23:03:41 +0000 |
| parents | 022ece8c8705 |
| children | e92dd3fb3ec8 |
| files | lib/mktime.c |
| diffstat | 1 files changed, 23 insertions(+), 11 deletions(-) [+] |
line wrap: on
line diff
--- a/lib/mktime.c +++ b/lib/mktime.c @@ -29,8 +29,8 @@ #endif /* Some systems need this in order to declare localtime_r properly. */ -#ifndef _REENTRANT -# define _REENTRANT 1 +#ifndef __EXTENSIONS__ +# define __EXTENSIONS__ 1 #endif #ifdef _LIBC @@ -270,14 +270,14 @@ struct tm *(*convert) __P ((const time_t *, struct tm *)); time_t *offset; { - time_t t, dt, t0; + time_t t, dt, t0, t1, t2; struct tm tm; /* The maximum number of probes (calls to CONVERT) should be enough to handle any combinations of time zone rule changes, solar time, - and leap seconds. POSIX.1 prohibits leap seconds, but some hosts - have them anyway. */ - int remaining_probes = 4; + leap seconds, and oscillations around a spring-forward gap. + POSIX.1 prohibits leap seconds, but some hosts have them anyway. */ + int remaining_probes = 6; /* Time requested. Copy it in case CONVERT modifies *TP; this can occur if TP is localtime's returned value and CONVERT is localtime. */ @@ -323,15 +323,27 @@ tm.tm_yday = tm.tm_hour = tm.tm_min = tm.tm_sec = 0; t0 = ydhms_tm_diff (year, yday, hour, min, sec, &tm); - for (t = t0 + *offset; + for (t = t1 = t2 = t0 + *offset; (dt = ydhms_tm_diff (year, yday, hour, min, sec, ranged_convert (convert, &t, &tm))); - t += dt) - if (--remaining_probes == 0) + t1 = t2, t2 = t, t += dt) + if (t == t1 && t != t2 + && (isdst < 0 || tm.tm_isdst < 0 + || (isdst != 0) != (tm.tm_isdst != 0))) + /* We can't possibly find a match, as we are oscillating + between two values. The requested time probably falls + within a spring-forward gap of size DT. Follow the common + practice in this case, which is to return a time that is DT + away from the requested time, preferring a time whose + tm_isdst differs from the requested value. In practice, + this is more useful than returning -1. */ + break; + else if (--remaining_probes == 0) return -1; - /* Check whether tm.tm_isdst has the requested value, if any. */ - if (0 <= isdst && 0 <= tm.tm_isdst) + /* 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) { int dst_diff = (isdst != 0) - (tm.tm_isdst != 0); if (dst_diff)