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1 | /* Convert a 'struct tm' to a time_t value. | |
2 | Copyright (C) 1993-2016 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 | \f | |
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 | \f | |
737 | /* | |
738 | Local Variables: | |
739 | compile-command: "gcc -DDEBUG_MKTIME -I. -Wall -W -O2 -g mktime.c -o mktime" | |
740 | End: | |
741 | */ |