* manual/signal.texi (Signaling Another Process): Typo fix.
[glibc.git] / time / mktime.c
blob8f00c72e09ab4f1db4be3a7042a4a2a262eb1710
1 /* Convert a `struct tm' to a time_t value.
2 Copyright (C) 1993-1999, 2002-2005, 2006 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Paul Eggert <eggert@twinsun.com>.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19 02111-1307 USA. */
21 /* Define this to have a standalone program to test this implementation of
22 mktime. */
23 /* #define DEBUG 1 */
25 #ifdef HAVE_CONFIG_H
26 # include <config.h>
27 #endif
29 /* Assume that leap seconds are possible, unless told otherwise.
30 If the host has a `zic' command with a `-L leapsecondfilename' option,
31 then it supports leap seconds; otherwise it probably doesn't. */
32 #ifndef LEAP_SECONDS_POSSIBLE
33 # define LEAP_SECONDS_POSSIBLE 1
34 #endif
36 #include <sys/types.h> /* Some systems define `time_t' here. */
37 #include <time.h>
39 #include <limits.h>
41 #include <string.h> /* For the real memcpy prototype. */
43 #if DEBUG
44 # include <stdio.h>
45 # include <stdlib.h>
46 /* Make it work even if the system's libc has its own mktime routine. */
47 # define mktime my_mktime
48 #endif /* DEBUG */
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. */
60 #define SHR(a, b) \
61 (-1 >> 1 == -1 \
62 ? (a) >> (b) \
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
69 an integer. */
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
86 your host. */
87 #define TYPE_MINIMUM(t) \
88 ((t) (! TYPE_SIGNED (t) \
89 ? (t) 0 \
90 : TYPE_SIGNED_MAGNITUDE (t) \
91 ? ~ (t) 0 \
92 : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
93 #define TYPE_MAXIMUM(t) \
94 ((t) (! TYPE_SIGNED (t) \
95 ? (t) -1 \
96 : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
98 #ifndef TIME_T_MIN
99 # define TIME_T_MIN TYPE_MINIMUM (time_t)
100 #endif
101 #ifndef TIME_T_MAX
102 # define TIME_T_MAX TYPE_MAXIMUM (time_t)
103 #endif
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. */
120 static inline int
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. */
125 return
126 ((year & 3) == 0
127 && (year % 100 != 0
128 || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3)));
131 /* How many days come before each month (0-12). */
132 #ifndef _LIBC
133 static
134 #endif
135 const unsigned short int __mon_yday[2][13] =
137 /* Normal years. */
138 { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
139 /* Leap years. */
140 { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
144 #ifndef _LIBC
145 /* Portable standalone applications should supply a "time_r.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 # include "time_r.h"
150 # undef __localtime_r
151 # define __localtime_r localtime_r
152 # define __mktime_internal mktime_internal
153 #endif
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
164 detect overflow. */
166 static inline time_t
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 verify (long_int_year_and_yday_are_wide_enough,
172 INT_MAX <= LONG_MAX / 2 || TIME_T_MAX <= UINT_MAX);
174 /* Compute intervening leap days correctly even if year is negative.
175 Take care to avoid integer overflow here. */
176 int a4 = SHR (year1, 2) + SHR (TM_YEAR_BASE, 2) - ! (year1 & 3);
177 int b4 = SHR (year0, 2) + SHR (TM_YEAR_BASE, 2) - ! (year0 & 3);
178 int a100 = a4 / 25 - (a4 % 25 < 0);
179 int b100 = b4 / 25 - (b4 % 25 < 0);
180 int a400 = SHR (a100, 2);
181 int b400 = SHR (b100, 2);
182 int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
184 /* Compute the desired time in time_t precision. Overflow might
185 occur here. */
186 time_t tyear1 = year1;
187 time_t years = tyear1 - year0;
188 time_t days = 365 * years + yday1 - yday0 + intervening_leap_days;
189 time_t hours = 24 * days + hour1 - hour0;
190 time_t minutes = 60 * hours + min1 - min0;
191 time_t seconds = 60 * minutes + sec1 - sec0;
192 return seconds;
196 /* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC),
197 assuming that *T corresponds to *TP and that no clock adjustments
198 occurred between *TP and the desired time.
199 If TP is null, return a value not equal to *T; this avoids false matches.
200 If overflow occurs, yield the minimal or maximal value, except do not
201 yield a value equal to *T. */
202 static time_t
203 guess_time_tm (long int year, long int yday, int hour, int min, int sec,
204 const time_t *t, const struct tm *tp)
206 if (tp)
208 time_t d = ydhms_diff (year, yday, hour, min, sec,
209 tp->tm_year, tp->tm_yday,
210 tp->tm_hour, tp->tm_min, tp->tm_sec);
211 time_t t1 = *t + d;
212 if ((t1 < *t) == (TYPE_SIGNED (time_t) ? d < 0 : TIME_T_MAX / 2 < d))
213 return t1;
216 /* Overflow occurred one way or another. Return the nearest result
217 that is actually in range, except don't report a zero difference
218 if the actual difference is nonzero, as that would cause a false
219 match; and don't oscillate between two values, as that would
220 confuse the spring-forward gap detector. */
221 return (*t < TIME_T_MIDPOINT
222 ? (*t <= TIME_T_MIN + 1 ? *t + 1 : TIME_T_MIN)
223 : (TIME_T_MAX - 1 <= *t ? *t - 1 : TIME_T_MAX));
226 /* Use CONVERT to convert *T to a broken down time in *TP.
227 If *T is out of range for conversion, adjust it so that
228 it is the nearest in-range value and then convert that. */
229 static struct tm *
230 ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
231 time_t *t, struct tm *tp)
233 struct tm *r = convert (t, tp);
235 if (!r && *t)
237 time_t bad = *t;
238 time_t ok = 0;
240 /* BAD is a known unconvertible time_t, and OK is a known good one.
241 Use binary search to narrow the range between BAD and OK until
242 they differ by 1. */
243 while (bad != ok + (bad < 0 ? -1 : 1))
245 time_t mid = *t = (bad < 0
246 ? bad + ((ok - bad) >> 1)
247 : ok + ((bad - ok) >> 1));
248 r = convert (t, tp);
249 if (r)
250 ok = mid;
251 else
252 bad = mid;
255 if (!r && ok)
257 /* The last conversion attempt failed;
258 revert to the most recent successful attempt. */
259 *t = ok;
260 r = convert (t, tp);
264 return r;
268 /* Convert *TP to a time_t value, inverting
269 the monotonic and mostly-unit-linear conversion function CONVERT.
270 Use *OFFSET to keep track of a guess at the offset of the result,
271 compared to what the result would be for UTC without leap seconds.
272 If *OFFSET's guess is correct, only one CONVERT call is needed.
273 This function is external because it is used also by timegm.c. */
274 time_t
275 __mktime_internal (struct tm *tp,
276 struct tm *(*convert) (const time_t *, struct tm *),
277 time_t *offset)
279 time_t t, gt, t0, t1, t2;
280 struct tm tm;
282 /* The maximum number of probes (calls to CONVERT) should be enough
283 to handle any combinations of time zone rule changes, solar time,
284 leap seconds, and oscillations around a spring-forward gap.
285 POSIX.1 prohibits leap seconds, but some hosts have them anyway. */
286 int remaining_probes = 6;
288 /* Time requested. Copy it in case CONVERT modifies *TP; this can
289 occur if TP is localtime's returned value and CONVERT is localtime. */
290 int sec = tp->tm_sec;
291 int min = tp->tm_min;
292 int hour = tp->tm_hour;
293 int mday = tp->tm_mday;
294 int mon = tp->tm_mon;
295 int year_requested = tp->tm_year;
296 int isdst = tp->tm_isdst;
298 /* 1 if the previous probe was DST. */
299 int dst2;
301 /* Ensure that mon is in range, and set year accordingly. */
302 int mon_remainder = mon % 12;
303 int negative_mon_remainder = mon_remainder < 0;
304 int mon_years = mon / 12 - negative_mon_remainder;
305 long int lyear_requested = year_requested;
306 long int year = lyear_requested + mon_years;
308 /* The other values need not be in range:
309 the remaining code handles minor overflows correctly,
310 assuming int and time_t arithmetic wraps around.
311 Major overflows are caught at the end. */
313 /* Calculate day of year from year, month, and day of month.
314 The result need not be in range. */
315 int mon_yday = ((__mon_yday[leapyear (year)]
316 [mon_remainder + 12 * negative_mon_remainder])
317 - 1);
318 long int lmday = mday;
319 long int yday = mon_yday + lmday;
321 time_t guessed_offset = *offset;
323 int sec_requested = sec;
325 if (LEAP_SECONDS_POSSIBLE)
327 /* Handle out-of-range seconds specially,
328 since ydhms_tm_diff assumes every minute has 60 seconds. */
329 if (sec < 0)
330 sec = 0;
331 if (59 < sec)
332 sec = 59;
335 /* Invert CONVERT by probing. First assume the same offset as last
336 time. */
338 t0 = ydhms_diff (year, yday, hour, min, sec,
339 EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset);
341 if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
343 /* time_t isn't large enough to rule out overflows, so check
344 for major overflows. A gross check suffices, since if t0
345 has overflowed, it is off by a multiple of TIME_T_MAX -
346 TIME_T_MIN + 1. So ignore any component of the difference
347 that is bounded by a small value. */
349 /* Approximate log base 2 of the number of time units per
350 biennium. A biennium is 2 years; use this unit instead of
351 years to avoid integer overflow. For example, 2 average
352 Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds,
353 which is 63113904 seconds, and rint (log2 (63113904)) is
354 26. */
355 int ALOG2_SECONDS_PER_BIENNIUM = 26;
356 int ALOG2_MINUTES_PER_BIENNIUM = 20;
357 int ALOG2_HOURS_PER_BIENNIUM = 14;
358 int ALOG2_DAYS_PER_BIENNIUM = 10;
359 int LOG2_YEARS_PER_BIENNIUM = 1;
361 int approx_requested_biennia =
362 (SHR (year_requested, LOG2_YEARS_PER_BIENNIUM)
363 - SHR (EPOCH_YEAR - TM_YEAR_BASE, LOG2_YEARS_PER_BIENNIUM)
364 + SHR (mday, ALOG2_DAYS_PER_BIENNIUM)
365 + SHR (hour, ALOG2_HOURS_PER_BIENNIUM)
366 + SHR (min, ALOG2_MINUTES_PER_BIENNIUM)
367 + (LEAP_SECONDS_POSSIBLE
369 : SHR (sec, ALOG2_SECONDS_PER_BIENNIUM)));
371 int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM);
372 int diff = approx_biennia - approx_requested_biennia;
373 int abs_diff = diff < 0 ? - diff : diff;
375 /* IRIX 4.0.5 cc miscaculates TIME_T_MIN / 3: it erroneously
376 gives a positive value of 715827882. Setting a variable
377 first then doing math on it seems to work.
378 (ghazi@caip.rutgers.edu) */
379 time_t time_t_max = TIME_T_MAX;
380 time_t time_t_min = TIME_T_MIN;
381 time_t overflow_threshold =
382 (time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM;
384 if (overflow_threshold < abs_diff)
386 /* Overflow occurred. Try repairing it; this might work if
387 the time zone offset is enough to undo the overflow. */
388 time_t repaired_t0 = -1 - t0;
389 approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM);
390 diff = approx_biennia - approx_requested_biennia;
391 abs_diff = diff < 0 ? - diff : diff;
392 if (overflow_threshold < abs_diff)
393 return -1;
394 guessed_offset += repaired_t0 - t0;
395 t0 = repaired_t0;
399 /* Repeatedly use the error to improve the guess. */
401 for (t = t1 = t2 = t0, dst2 = 0;
402 (gt = guess_time_tm (year, yday, hour, min, sec, &t,
403 ranged_convert (convert, &t, &tm)),
404 t != gt);
405 t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0)
406 if (t == t1 && t != t2
407 && (tm.tm_isdst < 0
408 || (isdst < 0
409 ? dst2 <= (tm.tm_isdst != 0)
410 : (isdst != 0) != (tm.tm_isdst != 0))))
411 /* We can't possibly find a match, as we are oscillating
412 between two values. The requested time probably falls
413 within a spring-forward gap of size GT - T. Follow the common
414 practice in this case, which is to return a time that is GT - T
415 away from the requested time, preferring a time whose
416 tm_isdst differs from the requested value. (If no tm_isdst
417 was requested and only one of the two values has a nonzero
418 tm_isdst, prefer that value.) In practice, this is more
419 useful than returning -1. */
420 goto offset_found;
421 else if (--remaining_probes == 0)
422 return -1;
424 /* We have a match. Check whether tm.tm_isdst has the requested
425 value, if any. */
426 if (isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst)
428 /* tm.tm_isdst has the wrong value. Look for a neighboring
429 time with the right value, and use its UTC offset.
431 Heuristic: probe the adjacent timestamps in both directions,
432 looking for the desired isdst. This should work for all real
433 time zone histories in the tz database. */
435 /* Distance between probes when looking for a DST boundary. In
436 tzdata2003a, the shortest period of DST is 601200 seconds
437 (e.g., America/Recife starting 2000-10-08 01:00), and the
438 shortest period of non-DST surrounded by DST is 694800
439 seconds (Africa/Tunis starting 1943-04-17 01:00). Use the
440 minimum of these two values, so we don't miss these short
441 periods when probing. */
442 int stride = 601200;
444 /* The longest period of DST in tzdata2003a is 536454000 seconds
445 (e.g., America/Jujuy starting 1946-10-01 01:00). The longest
446 period of non-DST is much longer, but it makes no real sense
447 to search for more than a year of non-DST, so use the DST
448 max. */
449 int duration_max = 536454000;
451 /* Search in both directions, so the maximum distance is half
452 the duration; add the stride to avoid off-by-1 problems. */
453 int delta_bound = duration_max / 2 + stride;
455 int delta, direction;
457 for (delta = stride; delta < delta_bound; delta += stride)
458 for (direction = -1; direction <= 1; direction += 2)
460 time_t ot = t + delta * direction;
461 if ((ot < t) == (direction < 0))
463 struct tm otm;
464 ranged_convert (convert, &ot, &otm);
465 if (otm.tm_isdst == isdst)
467 /* We found the desired tm_isdst.
468 Extrapolate back to the desired time. */
469 t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm);
470 ranged_convert (convert, &t, &tm);
471 goto offset_found;
477 offset_found:
478 *offset = guessed_offset + t - t0;
480 if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec)
482 /* Adjust time to reflect the tm_sec requested, not the normalized value.
483 Also, repair any damage from a false match due to a leap second. */
484 int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec;
485 t1 = t + sec_requested;
486 t2 = t1 + sec_adjustment;
487 if (((t1 < t) != (sec_requested < 0))
488 | ((t2 < t1) != (sec_adjustment < 0))
489 | ! convert (&t2, &tm))
490 return -1;
491 t = t2;
494 *tp = tm;
495 return t;
499 /* FIXME: This should use a signed type wide enough to hold any UTC
500 offset in seconds. 'int' should be good enough for GNU code. We
501 can't fix this unilaterally though, as other modules invoke
502 __mktime_internal. */
503 static time_t localtime_offset;
505 /* Convert *TP to a time_t value. */
506 time_t
507 mktime (struct tm *tp)
509 #ifdef _LIBC
510 /* POSIX.1 8.1.1 requires that whenever mktime() is called, the
511 time zone names contained in the external variable `tzname' shall
512 be set as if the tzset() function had been called. */
513 __tzset ();
514 #endif
516 return __mktime_internal (tp, __localtime_r, &localtime_offset);
519 #ifdef weak_alias
520 weak_alias (mktime, timelocal)
521 #endif
523 #ifdef _LIBC
524 libc_hidden_def (mktime)
525 libc_hidden_weak (timelocal)
526 #endif
528 #if DEBUG
530 static int
531 not_equal_tm (const struct tm *a, const struct tm *b)
533 return ((a->tm_sec ^ b->tm_sec)
534 | (a->tm_min ^ b->tm_min)
535 | (a->tm_hour ^ b->tm_hour)
536 | (a->tm_mday ^ b->tm_mday)
537 | (a->tm_mon ^ b->tm_mon)
538 | (a->tm_year ^ b->tm_year)
539 | (a->tm_yday ^ b->tm_yday)
540 | (a->tm_isdst ^ b->tm_isdst));
543 static void
544 print_tm (const struct tm *tp)
546 if (tp)
547 printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d",
548 tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday,
549 tp->tm_hour, tp->tm_min, tp->tm_sec,
550 tp->tm_yday, tp->tm_wday, tp->tm_isdst);
551 else
552 printf ("0");
555 static int
556 check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt)
558 if (tk != tl || !lt || not_equal_tm (&tmk, lt))
560 printf ("mktime (");
561 print_tm (lt);
562 printf (")\nyields (");
563 print_tm (&tmk);
564 printf (") == %ld, should be %ld\n", (long int) tk, (long int) tl);
565 return 1;
568 return 0;
572 main (int argc, char **argv)
574 int status = 0;
575 struct tm tm, tmk, tml;
576 struct tm *lt;
577 time_t tk, tl, tl1;
578 char trailer;
580 if ((argc == 3 || argc == 4)
581 && (sscanf (argv[1], "%d-%d-%d%c",
582 &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer)
583 == 3)
584 && (sscanf (argv[2], "%d:%d:%d%c",
585 &tm.tm_hour, &tm.tm_min, &tm.tm_sec, &trailer)
586 == 3))
588 tm.tm_year -= TM_YEAR_BASE;
589 tm.tm_mon--;
590 tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]);
591 tmk = tm;
592 tl = mktime (&tmk);
593 lt = localtime (&tl);
594 if (lt)
596 tml = *lt;
597 lt = &tml;
599 printf ("mktime returns %ld == ", (long int) tl);
600 print_tm (&tmk);
601 printf ("\n");
602 status = check_result (tl, tmk, tl, lt);
604 else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0))
606 time_t from = atol (argv[1]);
607 time_t by = atol (argv[2]);
608 time_t to = atol (argv[3]);
610 if (argc == 4)
611 for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
613 lt = localtime (&tl);
614 if (lt)
616 tmk = tml = *lt;
617 tk = mktime (&tmk);
618 status |= check_result (tk, tmk, tl, &tml);
620 else
622 printf ("localtime (%ld) yields 0\n", (long int) tl);
623 status = 1;
625 tl1 = tl + by;
626 if ((tl1 < tl) != (by < 0))
627 break;
629 else
630 for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
632 /* Null benchmark. */
633 lt = localtime (&tl);
634 if (lt)
636 tmk = tml = *lt;
637 tk = tl;
638 status |= check_result (tk, tmk, tl, &tml);
640 else
642 printf ("localtime (%ld) yields 0\n", (long int) tl);
643 status = 1;
645 tl1 = tl + by;
646 if ((tl1 < tl) != (by < 0))
647 break;
650 else
651 printf ("Usage:\
652 \t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\
653 \t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\
654 \t%s FROM BY TO - # Do not test those values (for benchmark).\n",
655 argv[0], argv[0], argv[0]);
657 return status;
660 #endif /* DEBUG */
663 Local Variables:
664 compile-command: "gcc -DDEBUG -Wall -W -O -g mktime.c -o mktime"
665 End: