1 | /* Convert a 'struct tm' to a time_t value. |
2 | Copyright (C) 1993-2017 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | Contributed by Paul Eggert <eggert@twinsun.com>. |
5 | |
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. |
10 | |
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. |
15 | |
16 | You should have received a copy of the GNU Lesser General Public |
17 | License along with the GNU C Library; if not, see |
18 | <http://www.gnu.org/licenses/>. */ |
19 | |
20 | /* Define this to have a standalone program to test this implementation of |
21 | mktime. */ |
22 | /* #define DEBUG_MKTIME 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 defined DEBUG_MKTIME && DEBUG_MKTIME |
42 | # include <stdio.h> |
43 | # include <stdlib.h> |
44 | /* Make it work even if the system's libc has its own mktime routine. */ |
45 | # undef mktime |
46 | # define mktime my_mktime |
47 | #endif /* DEBUG_MKTIME */ |
48 | |
49 | /* Some of the code in this file assumes that signed integer overflow |
50 | silently wraps around. This assumption can't easily be programmed |
51 | around, nor can it be checked for portably at compile-time or |
52 | easily eliminated at run-time. |
53 | |
54 | Define WRAPV to 1 if the assumption is valid and if |
55 | #pragma GCC optimize ("wrapv") |
56 | does not trigger GCC bug 51793 |
57 | <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51793>. |
58 | Otherwise, define it to 0; this forces the use of slower code that, |
59 | while not guaranteed by the C Standard, works on all production |
60 | platforms that we know about. */ |
61 | #ifndef WRAPV |
62 | # if (((__GNUC__ == 4 && 4 <= __GNUC_MINOR__) || 4 < __GNUC__) \ |
63 | && defined __GLIBC__) |
64 | # pragma GCC optimize ("wrapv") |
65 | # define WRAPV 1 |
66 | # else |
67 | # define WRAPV 0 |
68 | # endif |
69 | #endif |
70 | |
71 | /* Verify a requirement at compile-time (unlike assert, which is runtime). */ |
72 | #define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; } |
73 | |
74 | /* A signed type that is at least one bit wider than int. */ |
75 | #if INT_MAX <= LONG_MAX / 2 |
76 | typedef long int long_int; |
77 | #else |
78 | typedef long long int long_int; |
79 | #endif |
80 | verify (long_int_is_wide_enough, INT_MAX == INT_MAX * (long_int) 2 / 2); |
81 | |
82 | /* Shift A right by B bits portably, by dividing A by 2**B and |
83 | truncating towards minus infinity. A and B should be free of side |
84 | effects, and B should be in the range 0 <= B <= INT_BITS - 2, where |
85 | INT_BITS is the number of useful bits in an int. GNU code can |
86 | assume that INT_BITS is at least 32. |
87 | |
88 | ISO C99 says that A >> B is implementation-defined if A < 0. Some |
89 | implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift |
90 | right in the usual way when A < 0, so SHR falls back on division if |
91 | ordinary A >> B doesn't seem to be the usual signed shift. */ |
92 | #define SHR(a, b) \ |
93 | ((-1 >> 1 == -1 \ |
94 | && (long_int) -1 >> 1 == -1 \ |
95 | && ((time_t) -1 >> 1 == -1 || ! TYPE_SIGNED (time_t))) \ |
96 | ? (a) >> (b) \ |
97 | : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0)) |
98 | |
99 | /* The extra casts in the following macros work around compiler bugs, |
100 | e.g., in Cray C 5.0.3.0. */ |
101 | |
102 | /* True if the arithmetic type T is an integer type. bool counts as |
103 | an integer. */ |
104 | #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1) |
105 | |
106 | /* True if negative values of the signed integer type T use two's |
107 | complement, or if T is an unsigned integer type. */ |
108 | #define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1) |
109 | |
110 | /* True if the arithmetic type T is signed. */ |
111 | #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) |
112 | |
113 | /* The maximum and minimum values for the integer type T. These |
114 | macros have undefined behavior if T is signed and has padding bits. |
115 | If this is a problem for you, please let us know how to fix it for |
116 | your host. */ |
117 | #define TYPE_MINIMUM(t) \ |
118 | ((t) (! TYPE_SIGNED (t) \ |
119 | ? (t) 0 \ |
120 | : ~ TYPE_MAXIMUM (t))) |
121 | #define TYPE_MAXIMUM(t) \ |
122 | ((t) (! TYPE_SIGNED (t) \ |
123 | ? (t) -1 \ |
124 | : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1))) |
125 | |
126 | #ifndef TIME_T_MIN |
127 | # define TIME_T_MIN TYPE_MINIMUM (time_t) |
128 | #endif |
129 | #ifndef TIME_T_MAX |
130 | # define TIME_T_MAX TYPE_MAXIMUM (time_t) |
131 | #endif |
132 | #define TIME_T_MIDPOINT (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1) |
133 | |
134 | verify (time_t_is_integer, TYPE_IS_INTEGER (time_t)); |
135 | verify (twos_complement_arithmetic, |
136 | (TYPE_TWOS_COMPLEMENT (int) |
137 | && TYPE_TWOS_COMPLEMENT (long_int) |
138 | && TYPE_TWOS_COMPLEMENT (time_t))); |
139 | |
140 | #define EPOCH_YEAR 1970 |
141 | #define TM_YEAR_BASE 1900 |
142 | verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0); |
143 | |
144 | /* Return 1 if YEAR + TM_YEAR_BASE is a leap year. */ |
145 | static int |
146 | leapyear (long_int year) |
147 | { |
148 | /* Don't add YEAR to TM_YEAR_BASE, as that might overflow. |
149 | Also, work even if YEAR is negative. */ |
150 | return |
151 | ((year & 3) == 0 |
152 | && (year % 100 != 0 |
153 | || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3))); |
154 | } |
155 | |
156 | /* How many days come before each month (0-12). */ |
157 | #ifndef _LIBC |
158 | static |
159 | #endif |
160 | const unsigned short int __mon_yday[2][13] = |
161 | { |
162 | /* Normal years. */ |
163 | { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, |
164 | /* Leap years. */ |
165 | { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } |
166 | }; |
167 | |
168 | |
169 | #ifndef _LIBC |
170 | /* Portable standalone applications should supply a <time.h> that |
171 | declares a POSIX-compliant localtime_r, for the benefit of older |
172 | implementations that lack localtime_r or have a nonstandard one. |
173 | See the gnulib time_r module for one way to implement this. */ |
174 | # undef __localtime_r |
175 | # define __localtime_r localtime_r |
176 | # define __mktime_internal mktime_internal |
177 | # include "mktime-internal.h" |
178 | #endif |
179 | |
180 | /* Return 1 if the values A and B differ according to the rules for |
181 | tm_isdst: A and B differ if one is zero and the other positive. */ |
182 | static int |
183 | isdst_differ (int a, int b) |
184 | { |
185 | return (!a != !b) && (0 <= a) && (0 <= b); |
186 | } |
187 | |
188 | /* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) - |
189 | (YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks |
190 | were not adjusted between the time stamps. |
191 | |
192 | The YEAR values uses the same numbering as TP->tm_year. Values |
193 | need not be in the usual range. However, YEAR1 must not be less |
194 | than 2 * INT_MIN or greater than 2 * INT_MAX. |
195 | |
196 | The result may overflow. It is the caller's responsibility to |
197 | detect overflow. */ |
198 | |
199 | static time_t |
200 | ydhms_diff (long_int year1, long_int yday1, int hour1, int min1, int sec1, |
201 | int year0, int yday0, int hour0, int min0, int sec0) |
202 | { |
203 | verify (C99_integer_division, -1 / 2 == 0); |
204 | |
205 | /* Compute intervening leap days correctly even if year is negative. |
206 | Take care to avoid integer overflow here. */ |
207 | int a4 = SHR (year1, 2) + SHR (TM_YEAR_BASE, 2) - ! (year1 & 3); |
208 | int b4 = SHR (year0, 2) + SHR (TM_YEAR_BASE, 2) - ! (year0 & 3); |
209 | int a100 = a4 / 25 - (a4 % 25 < 0); |
210 | int b100 = b4 / 25 - (b4 % 25 < 0); |
211 | int a400 = SHR (a100, 2); |
212 | int b400 = SHR (b100, 2); |
213 | int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400); |
214 | |
215 | /* Compute the desired time in time_t precision. Overflow might |
216 | occur here. */ |
217 | time_t tyear1 = year1; |
218 | time_t years = tyear1 - year0; |
219 | time_t days = 365 * years + yday1 - yday0 + intervening_leap_days; |
220 | time_t hours = 24 * days + hour1 - hour0; |
221 | time_t minutes = 60 * hours + min1 - min0; |
222 | time_t seconds = 60 * minutes + sec1 - sec0; |
223 | return seconds; |
224 | } |
225 | |
226 | /* Return the average of A and B, even if A + B would overflow. */ |
227 | static time_t |
228 | time_t_avg (time_t a, time_t b) |
229 | { |
230 | return SHR (a, 1) + SHR (b, 1) + (a & b & 1); |
231 | } |
232 | |
233 | /* Return 1 if A + B does not overflow. If time_t is unsigned and if |
234 | B's top bit is set, assume that the sum represents A - -B, and |
235 | return 1 if the subtraction does not wrap around. */ |
236 | static int |
237 | time_t_add_ok (time_t a, time_t b) |
238 | { |
239 | if (! TYPE_SIGNED (time_t)) |
240 | { |
241 | time_t sum = a + b; |
242 | return (sum < a) == (TIME_T_MIDPOINT <= b); |
243 | } |
244 | else if (WRAPV) |
245 | { |
246 | time_t sum = a + b; |
247 | return (sum < a) == (b < 0); |
248 | } |
249 | else |
250 | { |
251 | time_t avg = time_t_avg (a, b); |
252 | return TIME_T_MIN / 2 <= avg && avg <= TIME_T_MAX / 2; |
253 | } |
254 | } |
255 | |
256 | /* Return 1 if A + B does not overflow. */ |
257 | static int |
258 | time_t_int_add_ok (time_t a, int b) |
259 | { |
260 | verify (int_no_wider_than_time_t, INT_MAX <= TIME_T_MAX); |
261 | if (WRAPV) |
262 | { |
263 | time_t sum = a + b; |
264 | return (sum < a) == (b < 0); |
265 | } |
266 | else |
267 | { |
268 | int a_odd = a & 1; |
269 | time_t avg = SHR (a, 1) + (SHR (b, 1) + (a_odd & b)); |
270 | return TIME_T_MIN / 2 <= avg && avg <= TIME_T_MAX / 2; |
271 | } |
272 | } |
273 | |
274 | /* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC), |
275 | assuming that *T corresponds to *TP and that no clock adjustments |
276 | occurred between *TP and the desired time. |
277 | If TP is null, return a value not equal to *T; this avoids false matches. |
278 | If overflow occurs, yield the minimal or maximal value, except do not |
279 | yield a value equal to *T. */ |
280 | static time_t |
281 | guess_time_tm (long_int year, long_int yday, int hour, int min, int sec, |
282 | const time_t *t, const struct tm *tp) |
283 | { |
284 | if (tp) |
285 | { |
286 | time_t d = ydhms_diff (year, yday, hour, min, sec, |
287 | tp->tm_year, tp->tm_yday, |
288 | tp->tm_hour, tp->tm_min, tp->tm_sec); |
289 | if (time_t_add_ok (*t, d)) |
290 | return *t + d; |
291 | } |
292 | |
293 | /* Overflow occurred one way or another. Return the nearest result |
294 | that is actually in range, except don't report a zero difference |
295 | if the actual difference is nonzero, as that would cause a false |
296 | match; and don't oscillate between two values, as that would |
297 | confuse the spring-forward gap detector. */ |
298 | return (*t < TIME_T_MIDPOINT |
299 | ? (*t <= TIME_T_MIN + 1 ? *t + 1 : TIME_T_MIN) |
300 | : (TIME_T_MAX - 1 <= *t ? *t - 1 : TIME_T_MAX)); |
301 | } |
302 | |
303 | /* Use CONVERT to convert *T to a broken down time in *TP. |
304 | If *T is out of range for conversion, adjust it so that |
305 | it is the nearest in-range value and then convert that. */ |
306 | static struct tm * |
307 | ranged_convert (struct tm *(*convert) (const time_t *, struct tm *), |
308 | time_t *t, struct tm *tp) |
309 | { |
310 | struct tm *r = convert (t, tp); |
311 | |
312 | if (!r && *t) |
313 | { |
314 | time_t bad = *t; |
315 | time_t ok = 0; |
316 | |
317 | /* BAD is a known unconvertible time_t, and OK is a known good one. |
318 | Use binary search to narrow the range between BAD and OK until |
319 | they differ by 1. */ |
320 | while (bad != ok + (bad < 0 ? -1 : 1)) |
321 | { |
322 | time_t mid = *t = time_t_avg (ok, bad); |
323 | r = convert (t, tp); |
324 | if (r) |
325 | ok = mid; |
326 | else |
327 | bad = mid; |
328 | } |
329 | |
330 | if (!r && ok) |
331 | { |
332 | /* The last conversion attempt failed; |
333 | revert to the most recent successful attempt. */ |
334 | *t = ok; |
335 | r = convert (t, tp); |
336 | } |
337 | } |
338 | |
339 | return r; |
340 | } |
341 | |
342 | |
343 | /* Convert *TP to a time_t value, inverting |
344 | the monotonic and mostly-unit-linear conversion function CONVERT. |
345 | Use *OFFSET to keep track of a guess at the offset of the result, |
346 | compared to what the result would be for UTC without leap seconds. |
347 | If *OFFSET's guess is correct, only one CONVERT call is needed. |
348 | This function is external because it is used also by timegm.c. */ |
349 | time_t |
350 | __mktime_internal (struct tm *tp, |
351 | struct tm *(*convert) (const time_t *, struct tm *), |
352 | time_t *offset) |
353 | { |
354 | time_t t, gt, t0, t1, t2; |
355 | struct tm tm; |
356 | |
357 | /* The maximum number of probes (calls to CONVERT) should be enough |
358 | to handle any combinations of time zone rule changes, solar time, |
359 | leap seconds, and oscillations around a spring-forward gap. |
360 | POSIX.1 prohibits leap seconds, but some hosts have them anyway. */ |
361 | int remaining_probes = 6; |
362 | |
363 | /* Time requested. Copy it in case CONVERT modifies *TP; this can |
364 | occur if TP is localtime's returned value and CONVERT is localtime. */ |
365 | int sec = tp->tm_sec; |
366 | int min = tp->tm_min; |
367 | int hour = tp->tm_hour; |
368 | int mday = tp->tm_mday; |
369 | int mon = tp->tm_mon; |
370 | int year_requested = tp->tm_year; |
371 | int isdst = tp->tm_isdst; |
372 | |
373 | /* 1 if the previous probe was DST. */ |
374 | int dst2; |
375 | |
376 | /* Ensure that mon is in range, and set year accordingly. */ |
377 | int mon_remainder = mon % 12; |
378 | int negative_mon_remainder = mon_remainder < 0; |
379 | int mon_years = mon / 12 - negative_mon_remainder; |
380 | long_int lyear_requested = year_requested; |
381 | long_int year = lyear_requested + mon_years; |
382 | |
383 | /* The other values need not be in range: |
384 | the remaining code handles minor overflows correctly, |
385 | assuming int and time_t arithmetic wraps around. |
386 | Major overflows are caught at the end. */ |
387 | |
388 | /* Calculate day of year from year, month, and day of month. |
389 | The result need not be in range. */ |
390 | int mon_yday = ((__mon_yday[leapyear (year)] |
391 | [mon_remainder + 12 * negative_mon_remainder]) |
392 | - 1); |
393 | long_int lmday = mday; |
394 | long_int yday = mon_yday + lmday; |
395 | |
396 | time_t guessed_offset = *offset; |
397 | |
398 | int sec_requested = sec; |
399 | |
400 | if (LEAP_SECONDS_POSSIBLE) |
401 | { |
402 | /* Handle out-of-range seconds specially, |
403 | since ydhms_tm_diff assumes every minute has 60 seconds. */ |
404 | if (sec < 0) |
405 | sec = 0; |
406 | if (59 < sec) |
407 | sec = 59; |
408 | } |
409 | |
410 | /* Invert CONVERT by probing. First assume the same offset as last |
411 | time. */ |
412 | |
413 | t0 = ydhms_diff (year, yday, hour, min, sec, |
414 | EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset); |
415 | |
416 | if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3) |
417 | { |
418 | /* time_t isn't large enough to rule out overflows, so check |
419 | for major overflows. A gross check suffices, since if t0 |
420 | has overflowed, it is off by a multiple of TIME_T_MAX - |
421 | TIME_T_MIN + 1. So ignore any component of the difference |
422 | that is bounded by a small value. */ |
423 | |
424 | /* Approximate log base 2 of the number of time units per |
425 | biennium. A biennium is 2 years; use this unit instead of |
426 | years to avoid integer overflow. For example, 2 average |
427 | Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds, |
428 | which is 63113904 seconds, and rint (log2 (63113904)) is |
429 | 26. */ |
430 | int ALOG2_SECONDS_PER_BIENNIUM = 26; |
431 | int ALOG2_MINUTES_PER_BIENNIUM = 20; |
432 | int ALOG2_HOURS_PER_BIENNIUM = 14; |
433 | int ALOG2_DAYS_PER_BIENNIUM = 10; |
434 | int LOG2_YEARS_PER_BIENNIUM = 1; |
435 | |
436 | int approx_requested_biennia = |
437 | (SHR (year_requested, LOG2_YEARS_PER_BIENNIUM) |
438 | - SHR (EPOCH_YEAR - TM_YEAR_BASE, LOG2_YEARS_PER_BIENNIUM) |
439 | + SHR (mday, ALOG2_DAYS_PER_BIENNIUM) |
440 | + SHR (hour, ALOG2_HOURS_PER_BIENNIUM) |
441 | + SHR (min, ALOG2_MINUTES_PER_BIENNIUM) |
442 | + (LEAP_SECONDS_POSSIBLE |
443 | ? 0 |
444 | : SHR (sec, ALOG2_SECONDS_PER_BIENNIUM))); |
445 | |
446 | int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM); |
447 | int diff = approx_biennia - approx_requested_biennia; |
448 | int approx_abs_diff = diff < 0 ? -1 - diff : diff; |
449 | |
450 | /* IRIX 4.0.5 cc miscalculates TIME_T_MIN / 3: it erroneously |
451 | gives a positive value of 715827882. Setting a variable |
452 | first then doing math on it seems to work. |
453 | (ghazi@caip.rutgers.edu) */ |
454 | time_t time_t_max = TIME_T_MAX; |
455 | time_t time_t_min = TIME_T_MIN; |
456 | time_t overflow_threshold = |
457 | (time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM; |
458 | |
459 | if (overflow_threshold < approx_abs_diff) |
460 | { |
461 | /* Overflow occurred. Try repairing it; this might work if |
462 | the time zone offset is enough to undo the overflow. */ |
463 | time_t repaired_t0 = -1 - t0; |
464 | approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM); |
465 | diff = approx_biennia - approx_requested_biennia; |
466 | approx_abs_diff = diff < 0 ? -1 - diff : diff; |
467 | if (overflow_threshold < approx_abs_diff) |
468 | return -1; |
469 | guessed_offset += repaired_t0 - t0; |
470 | t0 = repaired_t0; |
471 | } |
472 | } |
473 | |
474 | /* Repeatedly use the error to improve the guess. */ |
475 | |
476 | for (t = t1 = t2 = t0, dst2 = 0; |
477 | (gt = guess_time_tm (year, yday, hour, min, sec, &t, |
478 | ranged_convert (convert, &t, &tm)), |
479 | t != gt); |
480 | t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0) |
481 | if (t == t1 && t != t2 |
482 | && (tm.tm_isdst < 0 |
483 | || (isdst < 0 |
484 | ? dst2 <= (tm.tm_isdst != 0) |
485 | : (isdst != 0) != (tm.tm_isdst != 0)))) |
486 | /* We can't possibly find a match, as we are oscillating |
487 | between two values. The requested time probably falls |
488 | within a spring-forward gap of size GT - T. Follow the common |
489 | practice in this case, which is to return a time that is GT - T |
490 | away from the requested time, preferring a time whose |
491 | tm_isdst differs from the requested value. (If no tm_isdst |
492 | was requested and only one of the two values has a nonzero |
493 | tm_isdst, prefer that value.) In practice, this is more |
494 | useful than returning -1. */ |
495 | goto offset_found; |
496 | else if (--remaining_probes == 0) |
497 | return -1; |
498 | |
499 | /* We have a match. Check whether tm.tm_isdst has the requested |
500 | value, if any. */ |
501 | if (isdst_differ (isdst, tm.tm_isdst)) |
502 | { |
503 | /* tm.tm_isdst has the wrong value. Look for a neighboring |
504 | time with the right value, and use its UTC offset. |
505 | |
506 | Heuristic: probe the adjacent timestamps in both directions, |
507 | looking for the desired isdst. This should work for all real |
508 | time zone histories in the tz database. */ |
509 | |
510 | /* Distance between probes when looking for a DST boundary. In |
511 | tzdata2003a, the shortest period of DST is 601200 seconds |
512 | (e.g., America/Recife starting 2000-10-08 01:00), and the |
513 | shortest period of non-DST surrounded by DST is 694800 |
514 | seconds (Africa/Tunis starting 1943-04-17 01:00). Use the |
515 | minimum of these two values, so we don't miss these short |
516 | periods when probing. */ |
517 | int stride = 601200; |
518 | |
519 | /* The longest period of DST in tzdata2003a is 536454000 seconds |
520 | (e.g., America/Jujuy starting 1946-10-01 01:00). The longest |
521 | period of non-DST is much longer, but it makes no real sense |
522 | to search for more than a year of non-DST, so use the DST |
523 | max. */ |
524 | int duration_max = 536454000; |
525 | |
526 | /* Search in both directions, so the maximum distance is half |
527 | the duration; add the stride to avoid off-by-1 problems. */ |
528 | int delta_bound = duration_max / 2 + stride; |
529 | |
530 | int delta, direction; |
531 | |
532 | for (delta = stride; delta < delta_bound; delta += stride) |
533 | for (direction = -1; direction <= 1; direction += 2) |
534 | if (time_t_int_add_ok (t, delta * direction)) |
535 | { |
536 | time_t ot = t + delta * direction; |
537 | struct tm otm; |
538 | ranged_convert (convert, &ot, &otm); |
539 | if (! isdst_differ (isdst, otm.tm_isdst)) |
540 | { |
541 | /* We found the desired tm_isdst. |
542 | Extrapolate back to the desired time. */ |
543 | t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm); |
544 | ranged_convert (convert, &t, &tm); |
545 | goto offset_found; |
546 | } |
547 | } |
548 | } |
549 | |
550 | offset_found: |
551 | *offset = guessed_offset + t - t0; |
552 | |
553 | if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec) |
554 | { |
555 | /* Adjust time to reflect the tm_sec requested, not the normalized value. |
556 | Also, repair any damage from a false match due to a leap second. */ |
557 | int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec; |
558 | if (! time_t_int_add_ok (t, sec_requested)) |
559 | return -1; |
560 | t1 = t + sec_requested; |
561 | if (! time_t_int_add_ok (t1, sec_adjustment)) |
562 | return -1; |
563 | t2 = t1 + sec_adjustment; |
564 | if (! convert (&t2, &tm)) |
565 | return -1; |
566 | t = t2; |
567 | } |
568 | |
569 | *tp = tm; |
570 | return t; |
571 | } |
572 | |
573 | |
574 | /* FIXME: This should use a signed type wide enough to hold any UTC |
575 | offset in seconds. 'int' should be good enough for GNU code. We |
576 | can't fix this unilaterally though, as other modules invoke |
577 | __mktime_internal. */ |
578 | static time_t localtime_offset; |
579 | |
580 | /* Convert *TP to a time_t value. */ |
581 | time_t |
582 | mktime (struct tm *tp) |
583 | { |
584 | #ifdef _LIBC |
585 | /* POSIX.1 8.1.1 requires that whenever mktime() is called, the |
586 | time zone names contained in the external variable 'tzname' shall |
587 | be set as if the tzset() function had been called. */ |
588 | __tzset (); |
589 | #endif |
590 | |
591 | return __mktime_internal (tp, __localtime_r, &localtime_offset); |
592 | } |
593 | |
594 | #ifdef weak_alias |
595 | weak_alias (mktime, timelocal) |
596 | #endif |
597 | |
598 | #ifdef _LIBC |
599 | libc_hidden_def (mktime) |
600 | libc_hidden_weak (timelocal) |
601 | #endif |
602 | |
603 | #if defined DEBUG_MKTIME && DEBUG_MKTIME |
604 | |
605 | static int |
606 | not_equal_tm (const struct tm *a, const struct tm *b) |
607 | { |
608 | return ((a->tm_sec ^ b->tm_sec) |
609 | | (a->tm_min ^ b->tm_min) |
610 | | (a->tm_hour ^ b->tm_hour) |
611 | | (a->tm_mday ^ b->tm_mday) |
612 | | (a->tm_mon ^ b->tm_mon) |
613 | | (a->tm_year ^ b->tm_year) |
614 | | (a->tm_yday ^ b->tm_yday) |
615 | | isdst_differ (a->tm_isdst, b->tm_isdst)); |
616 | } |
617 | |
618 | static void |
619 | print_tm (const struct tm *tp) |
620 | { |
621 | if (tp) |
622 | printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d" , |
623 | tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday, |
624 | tp->tm_hour, tp->tm_min, tp->tm_sec, |
625 | tp->tm_yday, tp->tm_wday, tp->tm_isdst); |
626 | else |
627 | printf ("0" ); |
628 | } |
629 | |
630 | static int |
631 | check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt) |
632 | { |
633 | if (tk != tl || !lt || not_equal_tm (&tmk, lt)) |
634 | { |
635 | printf ("mktime (" ); |
636 | print_tm (lt); |
637 | printf (")\nyields (" ); |
638 | print_tm (&tmk); |
639 | printf (") == %ld, should be %ld\n" , (long int) tk, (long int) tl); |
640 | return 1; |
641 | } |
642 | |
643 | return 0; |
644 | } |
645 | |
646 | int |
647 | main (int argc, char **argv) |
648 | { |
649 | int status = 0; |
650 | struct tm tm, tmk, tml; |
651 | struct tm *lt; |
652 | time_t tk, tl, tl1; |
653 | char trailer; |
654 | |
655 | if ((argc == 3 || argc == 4) |
656 | && (sscanf (argv[1], "%d-%d-%d%c" , |
657 | &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer) |
658 | == 3) |
659 | && (sscanf (argv[2], "%d:%d:%d%c" , |
660 | &tm.tm_hour, &tm.tm_min, &tm.tm_sec, &trailer) |
661 | == 3)) |
662 | { |
663 | tm.tm_year -= TM_YEAR_BASE; |
664 | tm.tm_mon--; |
665 | tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]); |
666 | tmk = tm; |
667 | tl = mktime (&tmk); |
668 | lt = localtime (&tl); |
669 | if (lt) |
670 | { |
671 | tml = *lt; |
672 | lt = &tml; |
673 | } |
674 | printf ("mktime returns %ld == " , (long int) tl); |
675 | print_tm (&tmk); |
676 | printf ("\n" ); |
677 | status = check_result (tl, tmk, tl, lt); |
678 | } |
679 | else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-" ) == 0)) |
680 | { |
681 | time_t from = atol (argv[1]); |
682 | time_t by = atol (argv[2]); |
683 | time_t to = atol (argv[3]); |
684 | |
685 | if (argc == 4) |
686 | for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1) |
687 | { |
688 | lt = localtime (&tl); |
689 | if (lt) |
690 | { |
691 | tmk = tml = *lt; |
692 | tk = mktime (&tmk); |
693 | status |= check_result (tk, tmk, tl, &tml); |
694 | } |
695 | else |
696 | { |
697 | printf ("localtime (%ld) yields 0\n" , (long int) tl); |
698 | status = 1; |
699 | } |
700 | tl1 = tl + by; |
701 | if ((tl1 < tl) != (by < 0)) |
702 | break; |
703 | } |
704 | else |
705 | for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1) |
706 | { |
707 | /* Null benchmark. */ |
708 | lt = localtime (&tl); |
709 | if (lt) |
710 | { |
711 | tmk = tml = *lt; |
712 | tk = tl; |
713 | status |= check_result (tk, tmk, tl, &tml); |
714 | } |
715 | else |
716 | { |
717 | printf ("localtime (%ld) yields 0\n" , (long int) tl); |
718 | status = 1; |
719 | } |
720 | tl1 = tl + by; |
721 | if ((tl1 < tl) != (by < 0)) |
722 | break; |
723 | } |
724 | } |
725 | else |
726 | printf ("Usage:\ |
727 | \t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\ |
728 | \t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\ |
729 | \t%s FROM BY TO - # Do not test those values (for benchmark).\n" , |
730 | argv[0], argv[0], argv[0]); |
731 | |
732 | return status; |
733 | } |
734 | |
735 | #endif /* DEBUG_MKTIME */ |
736 | |
737 | /* |
738 | Local Variables: |
739 | compile-command: "gcc -DDEBUG_MKTIME -I. -Wall -W -O2 -g mktime.c -o mktime" |
740 | End: |
741 | */ |
742 | |