1 /* -*- buffer-read-only: t -*- vi: set ro: */
2 /* DO NOT EDIT! GENERATED AUTOMATICALLY! */
3 /* Convert a `struct tm' to a time_t value.
4 Copyright (C) 1993-1999, 2002-2007, 2009-2010 Free Software Foundation, Inc.
5 This file is part of the GNU C Library.
6 Contributed by Paul Eggert <eggert@twinsun.com>.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License along
19 with this program; if not, write to the Free Software Foundation,
20 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
22 /* Define this to have a standalone program to test this implementation of
30 /* Assume that leap seconds are possible, unless told otherwise.
31 If the host has a `zic' command with a `-L leapsecondfilename' option,
32 then it supports leap seconds; otherwise it probably doesn't. */
33 #ifndef LEAP_SECONDS_POSSIBLE
34 # define LEAP_SECONDS_POSSIBLE 1
41 #include <string.h> /* For the real memcpy prototype. */
46 /* Make it work even if the system's libc has its own mktime routine. */
47 # define mktime my_mktime
50 /* Shift A right by B bits portably, by dividing A by 2**B and
51 truncating towards minus infinity. A and B should be free of side
52 effects, and B should be in the range 0 <= B <= INT_BITS - 2, where
53 INT_BITS is the number of useful bits in an int. GNU code can
54 assume that INT_BITS is at least 32.
56 ISO C99 says that A >> B is implementation-defined if A < 0. Some
57 implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift
58 right in the usual way when A < 0, so SHR falls back on division if
59 ordinary A >> B doesn't seem to be the usual signed shift. */
63 : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0))
65 /* The extra casts in the following macros work around compiler bugs,
66 e.g., in Cray C 5.0.3.0. */
68 /* True if the arithmetic type T is an integer type. bool counts as
70 #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
72 /* True if negative values of the signed integer type T use two's
73 complement, ones' complement, or signed magnitude representation,
74 respectively. Much GNU code assumes two's complement, but some
75 people like to be portable to all possible C hosts. */
76 #define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
77 #define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
78 #define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
80 /* True if the arithmetic type T is signed. */
81 #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
83 /* The maximum and minimum values for the integer type T. These
84 macros have undefined behavior if T is signed and has padding bits.
85 If this is a problem for you, please let us know how to fix it for
87 #define TYPE_MINIMUM(t) \
88 ((t) (! TYPE_SIGNED (t) \
90 : TYPE_SIGNED_MAGNITUDE (t) \
92 : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
93 #define TYPE_MAXIMUM(t) \
94 ((t) (! TYPE_SIGNED (t) \
96 : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
99 # define TIME_T_MIN TYPE_MINIMUM (time_t)
102 # define TIME_T_MAX TYPE_MAXIMUM (time_t)
104 #define TIME_T_MIDPOINT (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1)
106 /* Verify a requirement at compile-time (unlike assert, which is runtime). */
107 #define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; }
109 verify (time_t_is_integer, TYPE_IS_INTEGER (time_t));
110 verify (twos_complement_arithmetic, TYPE_TWOS_COMPLEMENT (int));
111 /* The code also assumes that signed integer overflow silently wraps
112 around, but this assumption can't be stated without causing a
113 diagnostic on some hosts. */
115 #define EPOCH_YEAR 1970
116 #define TM_YEAR_BASE 1900
117 verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0);
119 /* Return 1 if YEAR + TM_YEAR_BASE is a leap year. */
121 leapyear (long int year)
123 /* Don't add YEAR to TM_YEAR_BASE, as that might overflow.
124 Also, work even if YEAR is negative. */
128 || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3)));
131 /* How many days come before each month (0-12). */
135 const unsigned short int __mon_yday[2][13] =
138 { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
140 { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
145 /* Portable standalone applications should supply a <time.h> that
146 declares a POSIX-compliant localtime_r, for the benefit of older
147 implementations that lack localtime_r or have a nonstandard one.
148 See the gnulib time_r module for one way to implement this. */
149 # undef __localtime_r
150 # define __localtime_r localtime_r
151 # define __mktime_internal mktime_internal
152 # include "mktime-internal.h"
155 /* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) -
156 (YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks
157 were not adjusted between the time stamps.
159 The YEAR values uses the same numbering as TP->tm_year. Values
160 need not be in the usual range. However, YEAR1 must not be less
161 than 2 * INT_MIN or greater than 2 * INT_MAX.
163 The result may overflow. It is the caller's responsibility to
167 ydhms_diff (long int year1, long int yday1, int hour1, int min1, int sec1,
168 int year0, int yday0, int hour0, int min0, int sec0)
170 verify (C99_integer_division, -1 / 2 == 0);
171 #if 0 /* This assertion fails on 32-bit systems with 64-bit time_t, such as
173 verify (long_int_year_and_yday_are_wide_enough,
174 INT_MAX <= LONG_MAX / 2 || TIME_T_MAX <= UINT_MAX);
177 /* Compute intervening leap days correctly even if year is negative.
178 Take care to avoid integer overflow here. */
179 int a4 = SHR (year1, 2) + SHR (TM_YEAR_BASE, 2) - ! (year1 & 3);
180 int b4 = SHR (year0, 2) + SHR (TM_YEAR_BASE, 2) - ! (year0 & 3);
181 int a100 = a4 / 25 - (a4 % 25 < 0);
182 int b100 = b4 / 25 - (b4 % 25 < 0);
183 int a400 = SHR (a100, 2);
184 int b400 = SHR (b100, 2);
185 int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
187 /* Compute the desired time in time_t precision. Overflow might
189 time_t tyear1 = year1;
190 time_t years = tyear1 - year0;
191 time_t days = 365 * years + yday1 - yday0 + intervening_leap_days;
192 time_t hours = 24 * days + hour1 - hour0;
193 time_t minutes = 60 * hours + min1 - min0;
194 time_t seconds = 60 * minutes + sec1 - sec0;
199 /* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC),
200 assuming that *T corresponds to *TP and that no clock adjustments
201 occurred between *TP and the desired time.
202 If TP is null, return a value not equal to *T; this avoids false matches.
203 If overflow occurs, yield the minimal or maximal value, except do not
204 yield a value equal to *T. */
206 guess_time_tm (long int year, long int yday, int hour, int min, int sec,
207 const time_t *t, const struct tm *tp)
211 time_t d = ydhms_diff (year, yday, hour, min, sec,
212 tp->tm_year, tp->tm_yday,
213 tp->tm_hour, tp->tm_min, tp->tm_sec);
215 if ((t1 < *t) == (TYPE_SIGNED (time_t) ? d < 0 : TIME_T_MAX / 2 < d))
219 /* Overflow occurred one way or another. Return the nearest result
220 that is actually in range, except don't report a zero difference
221 if the actual difference is nonzero, as that would cause a false
222 match; and don't oscillate between two values, as that would
223 confuse the spring-forward gap detector. */
224 return (*t < TIME_T_MIDPOINT
225 ? (*t <= TIME_T_MIN + 1 ? *t + 1 : TIME_T_MIN)
226 : (TIME_T_MAX - 1 <= *t ? *t - 1 : TIME_T_MAX));
229 /* Use CONVERT to convert *T to a broken down time in *TP.
230 If *T is out of range for conversion, adjust it so that
231 it is the nearest in-range value and then convert that. */
233 ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
234 time_t *t, struct tm *tp)
236 struct tm *r = convert (t, tp);
243 /* BAD is a known unconvertible time_t, and OK is a known good one.
244 Use binary search to narrow the range between BAD and OK until
246 while (bad != ok + (bad < 0 ? -1 : 1))
248 time_t mid = *t = (bad < 0
249 ? bad + ((ok - bad) >> 1)
250 : ok + ((bad - ok) >> 1));
260 /* The last conversion attempt failed;
261 revert to the most recent successful attempt. */
271 /* Convert *TP to a time_t value, inverting
272 the monotonic and mostly-unit-linear conversion function CONVERT.
273 Use *OFFSET to keep track of a guess at the offset of the result,
274 compared to what the result would be for UTC without leap seconds.
275 If *OFFSET's guess is correct, only one CONVERT call is needed.
276 This function is external because it is used also by timegm.c. */
278 __mktime_internal (struct tm *tp,
279 struct tm *(*convert) (const time_t *, struct tm *),
282 time_t t, gt, t0, t1, t2;
285 /* The maximum number of probes (calls to CONVERT) should be enough
286 to handle any combinations of time zone rule changes, solar time,
287 leap seconds, and oscillations around a spring-forward gap.
288 POSIX.1 prohibits leap seconds, but some hosts have them anyway. */
289 int remaining_probes = 6;
291 /* Time requested. Copy it in case CONVERT modifies *TP; this can
292 occur if TP is localtime's returned value and CONVERT is localtime. */
293 int sec = tp->tm_sec;
294 int min = tp->tm_min;
295 int hour = tp->tm_hour;
296 int mday = tp->tm_mday;
297 int mon = tp->tm_mon;
298 int year_requested = tp->tm_year;
299 /* Normalize the value. */
300 int isdst = ((tp->tm_isdst >> (8 * sizeof (tp->tm_isdst) - 1))
301 | (tp->tm_isdst != 0));
303 /* 1 if the previous probe was DST. */
306 /* Ensure that mon is in range, and set year accordingly. */
307 int mon_remainder = mon % 12;
308 int negative_mon_remainder = mon_remainder < 0;
309 int mon_years = mon / 12 - negative_mon_remainder;
310 long int lyear_requested = year_requested;
311 long int year = lyear_requested + mon_years;
313 /* The other values need not be in range:
314 the remaining code handles minor overflows correctly,
315 assuming int and time_t arithmetic wraps around.
316 Major overflows are caught at the end. */
318 /* Calculate day of year from year, month, and day of month.
319 The result need not be in range. */
320 int mon_yday = ((__mon_yday[leapyear (year)]
321 [mon_remainder + 12 * negative_mon_remainder])
323 long int lmday = mday;
324 long int yday = mon_yday + lmday;
326 time_t guessed_offset = *offset;
328 int sec_requested = sec;
330 if (LEAP_SECONDS_POSSIBLE)
332 /* Handle out-of-range seconds specially,
333 since ydhms_tm_diff assumes every minute has 60 seconds. */
340 /* Invert CONVERT by probing. First assume the same offset as last
343 t0 = ydhms_diff (year, yday, hour, min, sec,
344 EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset);
346 if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
348 /* time_t isn't large enough to rule out overflows, so check
349 for major overflows. A gross check suffices, since if t0
350 has overflowed, it is off by a multiple of TIME_T_MAX -
351 TIME_T_MIN + 1. So ignore any component of the difference
352 that is bounded by a small value. */
354 /* Approximate log base 2 of the number of time units per
355 biennium. A biennium is 2 years; use this unit instead of
356 years to avoid integer overflow. For example, 2 average
357 Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds,
358 which is 63113904 seconds, and rint (log2 (63113904)) is
360 int ALOG2_SECONDS_PER_BIENNIUM = 26;
361 int ALOG2_MINUTES_PER_BIENNIUM = 20;
362 int ALOG2_HOURS_PER_BIENNIUM = 14;
363 int ALOG2_DAYS_PER_BIENNIUM = 10;
364 int LOG2_YEARS_PER_BIENNIUM = 1;
366 int approx_requested_biennia =
367 (SHR (year_requested, LOG2_YEARS_PER_BIENNIUM)
368 - SHR (EPOCH_YEAR - TM_YEAR_BASE, LOG2_YEARS_PER_BIENNIUM)
369 + SHR (mday, ALOG2_DAYS_PER_BIENNIUM)
370 + SHR (hour, ALOG2_HOURS_PER_BIENNIUM)
371 + SHR (min, ALOG2_MINUTES_PER_BIENNIUM)
372 + (LEAP_SECONDS_POSSIBLE
374 : SHR (sec, ALOG2_SECONDS_PER_BIENNIUM)));
376 int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM);
377 int diff = approx_biennia - approx_requested_biennia;
378 int abs_diff = diff < 0 ? - diff : diff;
380 /* IRIX 4.0.5 cc miscaculates TIME_T_MIN / 3: it erroneously
381 gives a positive value of 715827882. Setting a variable
382 first then doing math on it seems to work.
383 (ghazi@caip.rutgers.edu) */
384 time_t time_t_max = TIME_T_MAX;
385 time_t time_t_min = TIME_T_MIN;
386 time_t overflow_threshold =
387 (time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM;
389 if (overflow_threshold < abs_diff)
391 /* Overflow occurred. Try repairing it; this might work if
392 the time zone offset is enough to undo the overflow. */
393 time_t repaired_t0 = -1 - t0;
394 approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM);
395 diff = approx_biennia - approx_requested_biennia;
396 abs_diff = diff < 0 ? - diff : diff;
397 if (overflow_threshold < abs_diff)
399 guessed_offset += repaired_t0 - t0;
404 /* Repeatedly use the error to improve the guess. */
406 for (t = t1 = t2 = t0, dst2 = 0;
407 (gt = guess_time_tm (year, yday, hour, min, sec, &t,
408 ranged_convert (convert, &t, &tm)),
410 t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0)
411 if (t == t1 && t != t2
414 ? dst2 <= (tm.tm_isdst != 0)
415 : (isdst != 0) != (tm.tm_isdst != 0))))
416 /* We can't possibly find a match, as we are oscillating
417 between two values. The requested time probably falls
418 within a spring-forward gap of size GT - T. Follow the common
419 practice in this case, which is to return a time that is GT - T
420 away from the requested time, preferring a time whose
421 tm_isdst differs from the requested value. (If no tm_isdst
422 was requested and only one of the two values has a nonzero
423 tm_isdst, prefer that value.) In practice, this is more
424 useful than returning -1. */
426 else if (--remaining_probes == 0)
429 /* We have a match. Check whether tm.tm_isdst has the requested
431 if (isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst)
433 /* tm.tm_isdst has the wrong value. Look for a neighboring
434 time with the right value, and use its UTC offset.
436 Heuristic: probe the adjacent timestamps in both directions,
437 looking for the desired isdst. This should work for all real
438 time zone histories in the tz database. */
440 /* Distance between probes when looking for a DST boundary. In
441 tzdata2003a, the shortest period of DST is 601200 seconds
442 (e.g., America/Recife starting 2000-10-08 01:00), and the
443 shortest period of non-DST surrounded by DST is 694800
444 seconds (Africa/Tunis starting 1943-04-17 01:00). Use the
445 minimum of these two values, so we don't miss these short
446 periods when probing. */
449 /* The longest period of DST in tzdata2003a is 536454000 seconds
450 (e.g., America/Jujuy starting 1946-10-01 01:00). The longest
451 period of non-DST is much longer, but it makes no real sense
452 to search for more than a year of non-DST, so use the DST
454 int duration_max = 536454000;
456 /* Search in both directions, so the maximum distance is half
457 the duration; add the stride to avoid off-by-1 problems. */
458 int delta_bound = duration_max / 2 + stride;
460 int delta, direction;
462 for (delta = stride; delta < delta_bound; delta += stride)
463 for (direction = -1; direction <= 1; direction += 2)
465 time_t ot = t + delta * direction;
466 if ((ot < t) == (direction < 0))
469 ranged_convert (convert, &ot, &otm);
470 if (otm.tm_isdst == isdst)
472 /* We found the desired tm_isdst.
473 Extrapolate back to the desired time. */
474 t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm);
475 ranged_convert (convert, &t, &tm);
483 *offset = guessed_offset + t - t0;
485 if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec)
487 /* Adjust time to reflect the tm_sec requested, not the normalized value.
488 Also, repair any damage from a false match due to a leap second. */
489 int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec;
490 t1 = t + sec_requested;
491 t2 = t1 + sec_adjustment;
492 if (((t1 < t) != (sec_requested < 0))
493 | ((t2 < t1) != (sec_adjustment < 0))
494 | ! convert (&t2, &tm))
504 /* FIXME: This should use a signed type wide enough to hold any UTC
505 offset in seconds. 'int' should be good enough for GNU code. We
506 can't fix this unilaterally though, as other modules invoke
507 __mktime_internal. */
508 static time_t localtime_offset;
510 /* Convert *TP to a time_t value. */
512 mktime (struct tm *tp)
515 /* POSIX.1 8.1.1 requires that whenever mktime() is called, the
516 time zone names contained in the external variable `tzname' shall
517 be set as if the tzset() function had been called. */
521 return __mktime_internal (tp, __localtime_r, &localtime_offset);
525 weak_alias (mktime, timelocal)
529 libc_hidden_def (mktime)
530 libc_hidden_weak (timelocal)
536 not_equal_tm (const struct tm *a, const struct tm *b)
538 return ((a->tm_sec ^ b->tm_sec)
539 | (a->tm_min ^ b->tm_min)
540 | (a->tm_hour ^ b->tm_hour)
541 | (a->tm_mday ^ b->tm_mday)
542 | (a->tm_mon ^ b->tm_mon)
543 | (a->tm_year ^ b->tm_year)
544 | (a->tm_yday ^ b->tm_yday)
545 | (a->tm_isdst ^ b->tm_isdst));
549 print_tm (const struct tm *tp)
552 printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d",
553 tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday,
554 tp->tm_hour, tp->tm_min, tp->tm_sec,
555 tp->tm_yday, tp->tm_wday, tp->tm_isdst);
561 check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt)
563 if (tk != tl || !lt || not_equal_tm (&tmk, lt))
567 printf (")\nyields (");
569 printf (") == %ld, should be %ld\n", (long int) tk, (long int) tl);
577 main (int argc, char **argv)
580 struct tm tm, tmk, tml;
585 if ((argc == 3 || argc == 4)
586 && (sscanf (argv[1], "%d-%d-%d%c",
587 &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer)
589 && (sscanf (argv[2], "%d:%d:%d%c",
590 &tm.tm_hour, &tm.tm_min, &tm.tm_sec, &trailer)
593 tm.tm_year -= TM_YEAR_BASE;
595 tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]);
598 lt = localtime (&tl);
604 printf ("mktime returns %ld == ", (long int) tl);
607 status = check_result (tl, tmk, tl, lt);
609 else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0))
611 time_t from = atol (argv[1]);
612 time_t by = atol (argv[2]);
613 time_t to = atol (argv[3]);
616 for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
618 lt = localtime (&tl);
623 status |= check_result (tk, tmk, tl, &tml);
627 printf ("localtime (%ld) yields 0\n", (long int) tl);
631 if ((tl1 < tl) != (by < 0))
635 for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
637 /* Null benchmark. */
638 lt = localtime (&tl);
643 status |= check_result (tk, tmk, tl, &tml);
647 printf ("localtime (%ld) yields 0\n", (long int) tl);
651 if ((tl1 < tl) != (by < 0))
657 \t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\
658 \t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\
659 \t%s FROM BY TO - # Do not test those values (for benchmark).\n",
660 argv[0], argv[0], argv[0]);
669 compile-command: "gcc -DDEBUG -Wall -W -O -g mktime.c -o mktime"