DUK_EXTERNAL duk_double_t duk_components_to_time(duk_context *ctx, duk_time_components *comp) {
duk_double_t d;
duk_double_t dparts[DUK_DATE_IDX_NUM_PARTS];
duk_uint_t flags;
DUK_ASSERT(ctx != NULL);
DUK_ASSERT(comp != NULL); /* XXX: or check? */
DUK_UNREF(ctx);
/* Match Date constructor behavior (with UTC time). Month is given
* as zero-based. Day-of-month is given as one-based so normalize
* it to zero-based as the internal conversion helpers expects all
* components to be zero-based.
*/
flags = 0;
/* XXX: expensive conversion; use array format in API instead, or unify
* time provider and time API to use same struct?
*/
dparts[DUK_DATE_IDX_YEAR] = comp->year;
dparts[DUK_DATE_IDX_MONTH] = comp->month;
dparts[DUK_DATE_IDX_DAY] = comp->day - 1.0;
dparts[DUK_DATE_IDX_HOUR] = comp->hours;
dparts[DUK_DATE_IDX_MINUTE] = comp->minutes;
dparts[DUK_DATE_IDX_SECOND] = comp->seconds;
dparts[DUK_DATE_IDX_MILLISECOND] = comp->milliseconds;
dparts[DUK_DATE_IDX_WEEKDAY] = 0; /* ignored */
d = duk_bi_date_get_timeval_from_dparts(dparts, flags);
return d;
}
/* Get local time offset (in seconds) for a certain (UTC) instant 'd'. */
DUK_INTERNAL duk_int_t duk_bi_date_get_local_tzoffset_gmtime(duk_double_t d) {
time_t t, t1, t2;
duk_int_t parts[DUK_DATE_IDX_NUM_PARTS];
duk_double_t dparts[DUK_DATE_IDX_NUM_PARTS];
struct tm tms[2];
#ifdef DUK_USE_DATE_TZO_GMTIME
struct tm *tm_ptr;
#endif
/* For NaN/inf, the return value doesn't matter. */
if (!DUK_ISFINITE(d)) {
return 0;
}
/* If not within Ecmascript range, some integer time calculations
* won't work correctly (and some asserts will fail), so bail out
* if so. This fixes test-bug-date-insane-setyear.js. There is
* a +/- 24h leeway in this range check to avoid a test262 corner
* case documented in test-bug-date-timeval-edges.js.
*/
if (!duk_bi_date_timeval_in_leeway_range(d)) {
DUK_DD(DUK_DDPRINT("timeval not within valid range, skip tzoffset computation to avoid integer overflows"));
return 0;
}
/*
* This is a bit tricky to implement portably. The result depends
* on the timestamp (specifically, DST depends on the timestamp).
* If e.g. UNIX APIs are used, they'll have portability issues with
* very small and very large years.
*
* Current approach:
*
* - Stay within portable UNIX limits by using equivalent year mapping.
* Avoid year 1970 and 2038 as some conversions start to fail, at
* least on some platforms. Avoiding 1970 means that there are
* currently DST discrepancies for 1970.
*
* - Create a UTC and local time breakdowns from 't'. Then create
* a time_t using gmtime() and localtime() and compute the time
* difference between the two.
*
* Equivalent year mapping (E5 Section 15.9.1.8):
*
* If the host environment provides functionality for determining
* daylight saving time, the implementation of ECMAScript is free
* to map the year in question to an equivalent year (same
* leap-year-ness and same starting week day for the year) for which
* the host environment provides daylight saving time information.
* The only restriction is that all equivalent years should produce
* the same result.
*
* This approach is quite reasonable but not entirely correct, e.g.
* the specification also states (E5 Section 15.9.1.8):
*
* The implementation of ECMAScript should not try to determine
* whether the exact time was subject to daylight saving time, but
* just whether daylight saving time would have been in effect if
* the _current daylight saving time algorithm_ had been used at the
* time. This avoids complications such as taking into account the
* years that the locale observed daylight saving time year round.
*
* Since we rely on the platform APIs for conversions between local
* time and UTC, we can't guarantee the above. Rather, if the platform
* has historical DST rules they will be applied. This seems to be the
* general preferred direction in Ecmascript standardization (or at least
* implementations) anyway, and even the equivalent year mapping should
* be disabled if the platform is known to handle DST properly for the
* full Ecmascript range.
*
* The following has useful discussion and links:
*
* https://bugzilla.mozilla.org/show_bug.cgi?id=351066
*/
duk_bi_date_timeval_to_parts(d, parts, dparts, DUK_DATE_FLAG_EQUIVYEAR /*flags*/);
DUK_ASSERT(parts[DUK_DATE_IDX_YEAR] >= 1970 && parts[DUK_DATE_IDX_YEAR] <= 2038);
d = duk_bi_date_get_timeval_from_dparts(dparts, 0 /*flags*/);
DUK_ASSERT(d >= 0 && d < 2147483648.0 * 1000.0); /* unsigned 31-bit range */
t = (time_t) (d / 1000.0);
DUK_DDD(DUK_DDDPRINT("timeval: %lf -> time_t %ld", (double) d, (long) t));
t1 = t;
DUK_MEMZERO((void *) tms, sizeof(struct tm) * 2);
#if defined(DUK_USE_DATE_TZO_GMTIME_R)
(void) gmtime_r(&t, &tms[0]);
(void) localtime_r(&t, &tms[1]);
#elif defined(DUK_USE_DATE_TZO_GMTIME)
tm_ptr = gmtime(&t);
DUK_MEMCPY((void *) &tms[0], tm_ptr, sizeof(struct tm));
tm_ptr = localtime(&t);
DUK_MEMCPY((void *) &tms[1], tm_ptr, sizeof(struct tm));
#else
#error internal error
#endif
DUK_DDD(DUK_DDDPRINT("gmtime result: tm={sec:%ld,min:%ld,hour:%ld,mday:%ld,mon:%ld,year:%ld,"
"wday:%ld,yday:%ld,isdst:%ld}",
(long) tms[0].tm_sec, (long) tms[0].tm_min, (long) tms[0].tm_hour,
(long) tms[0].tm_mday, (long) tms[0].tm_mon, (long) tms[0].tm_year,
(long) tms[0].tm_wday, (long) tms[0].tm_yday, (long) tms[0].tm_isdst));
DUK_DDD(DUK_DDDPRINT("localtime result: tm={sec:%ld,min:%ld,hour:%ld,mday:%ld,mon:%ld,year:%ld,"
"wday:%ld,yday:%ld,isdst:%ld}",
(long) tms[1].tm_sec, (long) tms[1].tm_min, (long) tms[1].tm_hour,
(long) tms[1].tm_mday, (long) tms[1].tm_mon, (long) tms[1].tm_year,
(long) tms[1].tm_wday, (long) tms[1].tm_yday, (long) tms[1].tm_isdst));
/* tm_isdst is both an input and an output to mktime(), use 0 to
* avoid DST handling in mktime():
* - https://github.com/svaarala/duktape/issues/406
* - http://stackoverflow.com/questions/8558919/mktime-and-tm-isdst
*/
tms[0].tm_isdst = 0;
tms[1].tm_isdst = 0;
t1 = mktime(&tms[0]); /* UTC */
t2 = mktime(&tms[1]); /* local */
if (t1 == (time_t) -1 || t2 == (time_t) -1) {
/* This check used to be for (t < 0) but on some platforms
* time_t is unsigned and apparently the proper way to detect
* an mktime() error return is the cast above. See e.g.:
* http://pubs.opengroup.org/onlinepubs/009695299/functions/mktime.html
*/
goto error;
}
DUK_DDD(DUK_DDDPRINT("t1=%ld (utc), t2=%ld (local)", (long) t1, (long) t2));
/* Compute final offset in seconds, positive if local time ahead of
* UTC (returned value is UTC-to-local offset).
*
* difftime() returns a double, so coercion to int generates quite
* a lot of code. Direct subtraction is not portable, however.
* XXX: allow direct subtraction on known platforms.
*/
#if 0
return (duk_int_t) (t2 - t1);
#endif
return (duk_int_t) difftime(t2, t1);
error:
/* XXX: return something more useful, so that caller can throw? */
DUK_D(DUK_DPRINT("mktime() failed, d=%lf", (double) d));
return 0;
}
