Merge from emacs-23
[bpt/emacs.git] / lib / mktime.c
1 /* Convert a `struct tm' to a time_t value.
2 Copyright (C) 1993-1999, 2002-2007, 2009-2011 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Paul Eggert <eggert@twinsun.com>.
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
9 any later version.
10
11 This program 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
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License along
17 with this program; if not, write to the Free Software Foundation,
18 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
19
20 /* Define this to have a standalone program to test this implementation of
21 mktime. */
22 /* #define DEBUG 1 */
23
24 #ifndef _LIBC
25 # include <config.h>
26 #endif
27
28 /* Assume that leap seconds are possible, unless told otherwise.
29 If the host has a `zic' command with a `-L leapsecondfilename' option,
30 then it supports leap seconds; otherwise it probably doesn't. */
31 #ifndef LEAP_SECONDS_POSSIBLE
32 # define LEAP_SECONDS_POSSIBLE 1
33 #endif
34
35 #include <time.h>
36
37 #include <limits.h>
38
39 #include <string.h> /* For the real memcpy prototype. */
40
41 #if DEBUG
42 # include <stdio.h>
43 # include <stdlib.h>
44 /* Make it work even if the system's libc has its own mktime routine. */
45 # define mktime my_mktime
46 #endif /* DEBUG */
47
48 /* Shift A right by B bits portably, by dividing A by 2**B and
49 truncating towards minus infinity. A and B should be free of side
50 effects, and B should be in the range 0 <= B <= INT_BITS - 2, where
51 INT_BITS is the number of useful bits in an int. GNU code can
52 assume that INT_BITS is at least 32.
53
54 ISO C99 says that A >> B is implementation-defined if A < 0. Some
55 implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift
56 right in the usual way when A < 0, so SHR falls back on division if
57 ordinary A >> B doesn't seem to be the usual signed shift. */
58 #define SHR(a, b) \
59 (-1 >> 1 == -1 \
60 ? (a) >> (b) \
61 : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0))
62
63 /* The extra casts in the following macros work around compiler bugs,
64 e.g., in Cray C 5.0.3.0. */
65
66 /* True if the arithmetic type T is an integer type. bool counts as
67 an integer. */
68 #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
69
70 /* True if negative values of the signed integer type T use two's
71 complement, ones' complement, or signed magnitude representation,
72 respectively. Much GNU code assumes two's complement, but some
73 people like to be portable to all possible C hosts. */
74 #define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
75 #define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
76 #define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
77
78 /* True if the arithmetic type T is signed. */
79 #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
80
81 /* The maximum and minimum values for the integer type T. These
82 macros have undefined behavior if T is signed and has padding bits.
83 If this is a problem for you, please let us know how to fix it for
84 your host. */
85 #define TYPE_MINIMUM(t) \
86 ((t) (! TYPE_SIGNED (t) \
87 ? (t) 0 \
88 : TYPE_SIGNED_MAGNITUDE (t) \
89 ? ~ (t) 0 \
90 : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
91 #define TYPE_MAXIMUM(t) \
92 ((t) (! TYPE_SIGNED (t) \
93 ? (t) -1 \
94 : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
95
96 #ifndef TIME_T_MIN
97 # define TIME_T_MIN TYPE_MINIMUM (time_t)
98 #endif
99 #ifndef TIME_T_MAX
100 # define TIME_T_MAX TYPE_MAXIMUM (time_t)
101 #endif
102 #define TIME_T_MIDPOINT (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1)
103
104 /* Verify a requirement at compile-time (unlike assert, which is runtime). */
105 #define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; }
106
107 verify (time_t_is_integer, TYPE_IS_INTEGER (time_t));
108 verify (twos_complement_arithmetic, TYPE_TWOS_COMPLEMENT (int));
109 /* The code also assumes that signed integer overflow silently wraps
110 around, but this assumption can't be stated without causing a
111 diagnostic on some hosts. */
112
113 #define EPOCH_YEAR 1970
114 #define TM_YEAR_BASE 1900
115 verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0);
116
117 /* Return 1 if YEAR + TM_YEAR_BASE is a leap year. */
118 static inline int
119 leapyear (long int year)
120 {
121 /* Don't add YEAR to TM_YEAR_BASE, as that might overflow.
122 Also, work even if YEAR is negative. */
123 return
124 ((year & 3) == 0
125 && (year % 100 != 0
126 || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3)));
127 }
128
129 /* How many days come before each month (0-12). */
130 #ifndef _LIBC
131 static
132 #endif
133 const unsigned short int __mon_yday[2][13] =
134 {
135 /* Normal years. */
136 { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
137 /* Leap years. */
138 { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
139 };
140
141
142 #ifndef _LIBC
143 /* Portable standalone applications should supply a <time.h> that
144 declares a POSIX-compliant localtime_r, for the benefit of older
145 implementations that lack localtime_r or have a nonstandard one.
146 See the gnulib time_r module for one way to implement this. */
147 # undef __localtime_r
148 # define __localtime_r localtime_r
149 # define __mktime_internal mktime_internal
150 # include "mktime-internal.h"
151 #endif
152
153 /* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) -
154 (YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks
155 were not adjusted between the time stamps.
156
157 The YEAR values uses the same numbering as TP->tm_year. Values
158 need not be in the usual range. However, YEAR1 must not be less
159 than 2 * INT_MIN or greater than 2 * INT_MAX.
160
161 The result may overflow. It is the caller's responsibility to
162 detect overflow. */
163
164 static inline time_t
165 ydhms_diff (long int year1, long int yday1, int hour1, int min1, int sec1,
166 int year0, int yday0, int hour0, int min0, int sec0)
167 {
168 verify (C99_integer_division, -1 / 2 == 0);
169 #if 0 /* This assertion fails on 32-bit systems with 64-bit time_t, such as
170 NetBSD 5 on i386. */
171 verify (long_int_year_and_yday_are_wide_enough,
172 INT_MAX <= LONG_MAX / 2 || TIME_T_MAX <= UINT_MAX);
173 #endif
174
175 /* Compute intervening leap days correctly even if year is negative.
176 Take care to avoid integer overflow here. */
177 int a4 = SHR (year1, 2) + SHR (TM_YEAR_BASE, 2) - ! (year1 & 3);
178 int b4 = SHR (year0, 2) + SHR (TM_YEAR_BASE, 2) - ! (year0 & 3);
179 int a100 = a4 / 25 - (a4 % 25 < 0);
180 int b100 = b4 / 25 - (b4 % 25 < 0);
181 int a400 = SHR (a100, 2);
182 int b400 = SHR (b100, 2);
183 int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
184
185 /* Compute the desired time in time_t precision. Overflow might
186 occur here. */
187 time_t tyear1 = year1;
188 time_t years = tyear1 - year0;
189 time_t days = 365 * years + yday1 - yday0 + intervening_leap_days;
190 time_t hours = 24 * days + hour1 - hour0;
191 time_t minutes = 60 * hours + min1 - min0;
192 time_t seconds = 60 * minutes + sec1 - sec0;
193 return seconds;
194 }
195
196
197 /* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC),
198 assuming that *T corresponds to *TP and that no clock adjustments
199 occurred between *TP and the desired time.
200 If TP is null, return a value not equal to *T; this avoids false matches.
201 If overflow occurs, yield the minimal or maximal value, except do not
202 yield a value equal to *T. */
203 static time_t
204 guess_time_tm (long int year, long int yday, int hour, int min, int sec,
205 const time_t *t, const struct tm *tp)
206 {
207 if (tp)
208 {
209 time_t d = ydhms_diff (year, yday, hour, min, sec,
210 tp->tm_year, tp->tm_yday,
211 tp->tm_hour, tp->tm_min, tp->tm_sec);
212 time_t t1 = *t + d;
213 if ((t1 < *t) == (TYPE_SIGNED (time_t) ? d < 0 : TIME_T_MAX / 2 < d))
214 return t1;
215 }
216
217 /* Overflow occurred one way or another. Return the nearest result
218 that is actually in range, except don't report a zero difference
219 if the actual difference is nonzero, as that would cause a false
220 match; and don't oscillate between two values, as that would
221 confuse the spring-forward gap detector. */
222 return (*t < TIME_T_MIDPOINT
223 ? (*t <= TIME_T_MIN + 1 ? *t + 1 : TIME_T_MIN)
224 : (TIME_T_MAX - 1 <= *t ? *t - 1 : TIME_T_MAX));
225 }
226
227 /* Use CONVERT to convert *T to a broken down time in *TP.
228 If *T is out of range for conversion, adjust it so that
229 it is the nearest in-range value and then convert that. */
230 static struct tm *
231 ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
232 time_t *t, struct tm *tp)
233 {
234 struct tm *r = convert (t, tp);
235
236 if (!r && *t)
237 {
238 time_t bad = *t;
239 time_t ok = 0;
240
241 /* BAD is a known unconvertible time_t, and OK is a known good one.
242 Use binary search to narrow the range between BAD and OK until
243 they differ by 1. */
244 while (bad != ok + (bad < 0 ? -1 : 1))
245 {
246 time_t mid = *t = (bad < 0
247 ? bad + ((ok - bad) >> 1)
248 : ok + ((bad - ok) >> 1));
249 r = convert (t, tp);
250 if (r)
251 ok = mid;
252 else
253 bad = mid;
254 }
255
256 if (!r && ok)
257 {
258 /* The last conversion attempt failed;
259 revert to the most recent successful attempt. */
260 *t = ok;
261 r = convert (t, tp);
262 }
263 }
264
265 return r;
266 }
267
268
269 /* Convert *TP to a time_t value, inverting
270 the monotonic and mostly-unit-linear conversion function CONVERT.
271 Use *OFFSET to keep track of a guess at the offset of the result,
272 compared to what the result would be for UTC without leap seconds.
273 If *OFFSET's guess is correct, only one CONVERT call is needed.
274 This function is external because it is used also by timegm.c. */
275 time_t
276 __mktime_internal (struct tm *tp,
277 struct tm *(*convert) (const time_t *, struct tm *),
278 time_t *offset)
279 {
280 time_t t, gt, t0, t1, t2;
281 struct tm tm;
282
283 /* The maximum number of probes (calls to CONVERT) should be enough
284 to handle any combinations of time zone rule changes, solar time,
285 leap seconds, and oscillations around a spring-forward gap.
286 POSIX.1 prohibits leap seconds, but some hosts have them anyway. */
287 int remaining_probes = 6;
288
289 /* Time requested. Copy it in case CONVERT modifies *TP; this can
290 occur if TP is localtime's returned value and CONVERT is localtime. */
291 int sec = tp->tm_sec;
292 int min = tp->tm_min;
293 int hour = tp->tm_hour;
294 int mday = tp->tm_mday;
295 int mon = tp->tm_mon;
296 int year_requested = tp->tm_year;
297 /* Normalize the value. */
298 int isdst = ((tp->tm_isdst >> (8 * sizeof (tp->tm_isdst) - 1))
299 | (tp->tm_isdst != 0));
300
301 /* 1 if the previous probe was DST. */
302 int dst2;
303
304 /* Ensure that mon is in range, and set year accordingly. */
305 int mon_remainder = mon % 12;
306 int negative_mon_remainder = mon_remainder < 0;
307 int mon_years = mon / 12 - negative_mon_remainder;
308 long int lyear_requested = year_requested;
309 long int year = lyear_requested + mon_years;
310
311 /* The other values need not be in range:
312 the remaining code handles minor overflows correctly,
313 assuming int and time_t arithmetic wraps around.
314 Major overflows are caught at the end. */
315
316 /* Calculate day of year from year, month, and day of month.
317 The result need not be in range. */
318 int mon_yday = ((__mon_yday[leapyear (year)]
319 [mon_remainder + 12 * negative_mon_remainder])
320 - 1);
321 long int lmday = mday;
322 long int yday = mon_yday + lmday;
323
324 time_t guessed_offset = *offset;
325
326 int sec_requested = sec;
327
328 if (LEAP_SECONDS_POSSIBLE)
329 {
330 /* Handle out-of-range seconds specially,
331 since ydhms_tm_diff assumes every minute has 60 seconds. */
332 if (sec < 0)
333 sec = 0;
334 if (59 < sec)
335 sec = 59;
336 }
337
338 /* Invert CONVERT by probing. First assume the same offset as last
339 time. */
340
341 t0 = ydhms_diff (year, yday, hour, min, sec,
342 EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset);
343
344 if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
345 {
346 /* time_t isn't large enough to rule out overflows, so check
347 for major overflows. A gross check suffices, since if t0
348 has overflowed, it is off by a multiple of TIME_T_MAX -
349 TIME_T_MIN + 1. So ignore any component of the difference
350 that is bounded by a small value. */
351
352 /* Approximate log base 2 of the number of time units per
353 biennium. A biennium is 2 years; use this unit instead of
354 years to avoid integer overflow. For example, 2 average
355 Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds,
356 which is 63113904 seconds, and rint (log2 (63113904)) is
357 26. */
358 int ALOG2_SECONDS_PER_BIENNIUM = 26;
359 int ALOG2_MINUTES_PER_BIENNIUM = 20;
360 int ALOG2_HOURS_PER_BIENNIUM = 14;
361 int ALOG2_DAYS_PER_BIENNIUM = 10;
362 int LOG2_YEARS_PER_BIENNIUM = 1;
363
364 int approx_requested_biennia =
365 (SHR (year_requested, LOG2_YEARS_PER_BIENNIUM)
366 - SHR (EPOCH_YEAR - TM_YEAR_BASE, LOG2_YEARS_PER_BIENNIUM)
367 + SHR (mday, ALOG2_DAYS_PER_BIENNIUM)
368 + SHR (hour, ALOG2_HOURS_PER_BIENNIUM)
369 + SHR (min, ALOG2_MINUTES_PER_BIENNIUM)
370 + (LEAP_SECONDS_POSSIBLE
371 ? 0
372 : SHR (sec, ALOG2_SECONDS_PER_BIENNIUM)));
373
374 int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM);
375 int diff = approx_biennia - approx_requested_biennia;
376 int abs_diff = diff < 0 ? - diff : diff;
377
378 /* IRIX 4.0.5 cc miscaculates TIME_T_MIN / 3: it erroneously
379 gives a positive value of 715827882. Setting a variable
380 first then doing math on it seems to work.
381 (ghazi@caip.rutgers.edu) */
382 time_t time_t_max = TIME_T_MAX;
383 time_t time_t_min = TIME_T_MIN;
384 time_t overflow_threshold =
385 (time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM;
386
387 if (overflow_threshold < abs_diff)
388 {
389 /* Overflow occurred. Try repairing it; this might work if
390 the time zone offset is enough to undo the overflow. */
391 time_t repaired_t0 = -1 - t0;
392 approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM);
393 diff = approx_biennia - approx_requested_biennia;
394 abs_diff = diff < 0 ? - diff : diff;
395 if (overflow_threshold < abs_diff)
396 return -1;
397 guessed_offset += repaired_t0 - t0;
398 t0 = repaired_t0;
399 }
400 }
401
402 /* Repeatedly use the error to improve the guess. */
403
404 for (t = t1 = t2 = t0, dst2 = 0;
405 (gt = guess_time_tm (year, yday, hour, min, sec, &t,
406 ranged_convert (convert, &t, &tm)),
407 t != gt);
408 t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0)
409 if (t == t1 && t != t2
410 && (tm.tm_isdst < 0
411 || (isdst < 0
412 ? dst2 <= (tm.tm_isdst != 0)
413 : (isdst != 0) != (tm.tm_isdst != 0))))
414 /* We can't possibly find a match, as we are oscillating
415 between two values. The requested time probably falls
416 within a spring-forward gap of size GT - T. Follow the common
417 practice in this case, which is to return a time that is GT - T
418 away from the requested time, preferring a time whose
419 tm_isdst differs from the requested value. (If no tm_isdst
420 was requested and only one of the two values has a nonzero
421 tm_isdst, prefer that value.) In practice, this is more
422 useful than returning -1. */
423 goto offset_found;
424 else if (--remaining_probes == 0)
425 return -1;
426
427 /* We have a match. Check whether tm.tm_isdst has the requested
428 value, if any. */
429 if (isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst)
430 {
431 /* tm.tm_isdst has the wrong value. Look for a neighboring
432 time with the right value, and use its UTC offset.
433
434 Heuristic: probe the adjacent timestamps in both directions,
435 looking for the desired isdst. This should work for all real
436 time zone histories in the tz database. */
437
438 /* Distance between probes when looking for a DST boundary. In
439 tzdata2003a, the shortest period of DST is 601200 seconds
440 (e.g., America/Recife starting 2000-10-08 01:00), and the
441 shortest period of non-DST surrounded by DST is 694800
442 seconds (Africa/Tunis starting 1943-04-17 01:00). Use the
443 minimum of these two values, so we don't miss these short
444 periods when probing. */
445 int stride = 601200;
446
447 /* The longest period of DST in tzdata2003a is 536454000 seconds
448 (e.g., America/Jujuy starting 1946-10-01 01:00). The longest
449 period of non-DST is much longer, but it makes no real sense
450 to search for more than a year of non-DST, so use the DST
451 max. */
452 int duration_max = 536454000;
453
454 /* Search in both directions, so the maximum distance is half
455 the duration; add the stride to avoid off-by-1 problems. */
456 int delta_bound = duration_max / 2 + stride;
457
458 int delta, direction;
459
460 for (delta = stride; delta < delta_bound; delta += stride)
461 for (direction = -1; direction <= 1; direction += 2)
462 {
463 time_t ot = t + delta * direction;
464 if ((ot < t) == (direction < 0))
465 {
466 struct tm otm;
467 ranged_convert (convert, &ot, &otm);
468 if (otm.tm_isdst == isdst)
469 {
470 /* We found the desired tm_isdst.
471 Extrapolate back to the desired time. */
472 t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm);
473 ranged_convert (convert, &t, &tm);
474 goto offset_found;
475 }
476 }
477 }
478 }
479
480 offset_found:
481 *offset = guessed_offset + t - t0;
482
483 if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec)
484 {
485 /* Adjust time to reflect the tm_sec requested, not the normalized value.
486 Also, repair any damage from a false match due to a leap second. */
487 int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec;
488 t1 = t + sec_requested;
489 t2 = t1 + sec_adjustment;
490 if (((t1 < t) != (sec_requested < 0))
491 | ((t2 < t1) != (sec_adjustment < 0))
492 | ! convert (&t2, &tm))
493 return -1;
494 t = t2;
495 }
496
497 *tp = tm;
498 return t;
499 }
500
501
502 /* FIXME: This should use a signed type wide enough to hold any UTC
503 offset in seconds. 'int' should be good enough for GNU code. We
504 can't fix this unilaterally though, as other modules invoke
505 __mktime_internal. */
506 static time_t localtime_offset;
507
508 /* Convert *TP to a time_t value. */
509 time_t
510 mktime (struct tm *tp)
511 {
512 #ifdef _LIBC
513 /* POSIX.1 8.1.1 requires that whenever mktime() is called, the
514 time zone names contained in the external variable `tzname' shall
515 be set as if the tzset() function had been called. */
516 __tzset ();
517 #endif
518
519 return __mktime_internal (tp, __localtime_r, &localtime_offset);
520 }
521
522 #ifdef weak_alias
523 weak_alias (mktime, timelocal)
524 #endif
525
526 #ifdef _LIBC
527 libc_hidden_def (mktime)
528 libc_hidden_weak (timelocal)
529 #endif
530 \f
531 #if DEBUG
532
533 static int
534 not_equal_tm (const struct tm *a, const struct tm *b)
535 {
536 return ((a->tm_sec ^ b->tm_sec)
537 | (a->tm_min ^ b->tm_min)
538 | (a->tm_hour ^ b->tm_hour)
539 | (a->tm_mday ^ b->tm_mday)
540 | (a->tm_mon ^ b->tm_mon)
541 | (a->tm_year ^ b->tm_year)
542 | (a->tm_yday ^ b->tm_yday)
543 | (a->tm_isdst ^ b->tm_isdst));
544 }
545
546 static void
547 print_tm (const struct tm *tp)
548 {
549 if (tp)
550 printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d",
551 tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday,
552 tp->tm_hour, tp->tm_min, tp->tm_sec,
553 tp->tm_yday, tp->tm_wday, tp->tm_isdst);
554 else
555 printf ("0");
556 }
557
558 static int
559 check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt)
560 {
561 if (tk != tl || !lt || not_equal_tm (&tmk, lt))
562 {
563 printf ("mktime (");
564 print_tm (lt);
565 printf (")\nyields (");
566 print_tm (&tmk);
567 printf (") == %ld, should be %ld\n", (long int) tk, (long int) tl);
568 return 1;
569 }
570
571 return 0;
572 }
573
574 int
575 main (int argc, char **argv)
576 {
577 int status = 0;
578 struct tm tm, tmk, tml;
579 struct tm *lt;
580 time_t tk, tl, tl1;
581 char trailer;
582
583 if ((argc == 3 || argc == 4)
584 && (sscanf (argv[1], "%d-%d-%d%c",
585 &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer)
586 == 3)
587 && (sscanf (argv[2], "%d:%d:%d%c",
588 &tm.tm_hour, &tm.tm_min, &tm.tm_sec, &trailer)
589 == 3))
590 {
591 tm.tm_year -= TM_YEAR_BASE;
592 tm.tm_mon--;
593 tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]);
594 tmk = tm;
595 tl = mktime (&tmk);
596 lt = localtime (&tl);
597 if (lt)
598 {
599 tml = *lt;
600 lt = &tml;
601 }
602 printf ("mktime returns %ld == ", (long int) tl);
603 print_tm (&tmk);
604 printf ("\n");
605 status = check_result (tl, tmk, tl, lt);
606 }
607 else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0))
608 {
609 time_t from = atol (argv[1]);
610 time_t by = atol (argv[2]);
611 time_t to = atol (argv[3]);
612
613 if (argc == 4)
614 for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
615 {
616 lt = localtime (&tl);
617 if (lt)
618 {
619 tmk = tml = *lt;
620 tk = mktime (&tmk);
621 status |= check_result (tk, tmk, tl, &tml);
622 }
623 else
624 {
625 printf ("localtime (%ld) yields 0\n", (long int) tl);
626 status = 1;
627 }
628 tl1 = tl + by;
629 if ((tl1 < tl) != (by < 0))
630 break;
631 }
632 else
633 for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
634 {
635 /* Null benchmark. */
636 lt = localtime (&tl);
637 if (lt)
638 {
639 tmk = tml = *lt;
640 tk = tl;
641 status |= check_result (tk, tmk, tl, &tml);
642 }
643 else
644 {
645 printf ("localtime (%ld) yields 0\n", (long int) tl);
646 status = 1;
647 }
648 tl1 = tl + by;
649 if ((tl1 < tl) != (by < 0))
650 break;
651 }
652 }
653 else
654 printf ("Usage:\
655 \t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\
656 \t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\
657 \t%s FROM BY TO - # Do not test those values (for benchmark).\n",
658 argv[0], argv[0], argv[0]);
659
660 return status;
661 }
662
663 #endif /* DEBUG */
664 \f
665 /*
666 Local Variables:
667 compile-command: "gcc -DDEBUG -Wall -W -O -g mktime.c -o mktime"
668 End:
669 */