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1fd182f0 PE |
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 | ||
3de84ad9 PE |
28 | /* Some of the code in this file assumes that signed integer overflow |
29 | silently wraps around. This assumption can't easily be programmed | |
30 | around, nor can it be checked for portably at compile-time or | |
31 | easily eliminated at run-time. | |
32 | ||
33 | Define WRAPV to 1 if the assumption is valid. Otherwise, define it | |
34 | to 0; this forces the use of slower code that, while not guaranteed | |
35 | by the C Standard, works on all production platforms that we know | |
36 | about. */ | |
37 | #ifndef WRAPV | |
38 | # if (__GNUC__ == 4 && 4 <= __GNUC_MINOR__) || 4 < __GNUC__ | |
39 | # pragma GCC optimize ("wrapv") | |
40 | # define WRAPV 1 | |
41 | # else | |
42 | # define WRAPV 0 | |
43 | # endif | |
44 | #endif | |
45 | ||
1fd182f0 PE |
46 | /* Assume that leap seconds are possible, unless told otherwise. |
47 | If the host has a `zic' command with a `-L leapsecondfilename' option, | |
48 | then it supports leap seconds; otherwise it probably doesn't. */ | |
49 | #ifndef LEAP_SECONDS_POSSIBLE | |
50 | # define LEAP_SECONDS_POSSIBLE 1 | |
51 | #endif | |
52 | ||
53 | #include <time.h> | |
54 | ||
55 | #include <limits.h> | |
56 | ||
57 | #include <string.h> /* For the real memcpy prototype. */ | |
58 | ||
59 | #if DEBUG | |
60 | # include <stdio.h> | |
61 | # include <stdlib.h> | |
62 | /* Make it work even if the system's libc has its own mktime routine. */ | |
3de84ad9 | 63 | # undef mktime |
1fd182f0 PE |
64 | # define mktime my_mktime |
65 | #endif /* DEBUG */ | |
66 | ||
3de84ad9 PE |
67 | /* Verify a requirement at compile-time (unlike assert, which is runtime). */ |
68 | #define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; } | |
69 | ||
70 | /* A signed type that is at least one bit wider than int. */ | |
71 | #if INT_MAX <= LONG_MAX / 2 | |
72 | typedef long int long_int; | |
73 | #else | |
74 | typedef long long int long_int; | |
75 | #endif | |
76 | verify (long_int_is_wide_enough, INT_MAX == INT_MAX * (long_int) 2 / 2); | |
77 | ||
1fd182f0 PE |
78 | /* Shift A right by B bits portably, by dividing A by 2**B and |
79 | truncating towards minus infinity. A and B should be free of side | |
80 | effects, and B should be in the range 0 <= B <= INT_BITS - 2, where | |
81 | INT_BITS is the number of useful bits in an int. GNU code can | |
82 | assume that INT_BITS is at least 32. | |
83 | ||
84 | ISO C99 says that A >> B is implementation-defined if A < 0. Some | |
85 | implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift | |
86 | right in the usual way when A < 0, so SHR falls back on division if | |
87 | ordinary A >> B doesn't seem to be the usual signed shift. */ | |
3de84ad9 PE |
88 | #define SHR(a, b) \ |
89 | ((-1 >> 1 == -1 \ | |
90 | && (long_int) -1 >> 1 == -1 \ | |
91 | && ((time_t) -1 >> 1 == -1 || ! TYPE_SIGNED (time_t))) \ | |
92 | ? (a) >> (b) \ | |
1fd182f0 PE |
93 | : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0)) |
94 | ||
95 | /* The extra casts in the following macros work around compiler bugs, | |
96 | e.g., in Cray C 5.0.3.0. */ | |
97 | ||
98 | /* True if the arithmetic type T is an integer type. bool counts as | |
99 | an integer. */ | |
100 | #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1) | |
101 | ||
102 | /* True if negative values of the signed integer type T use two's | |
3de84ad9 | 103 | complement, or if T is an unsigned integer type. */ |
1fd182f0 | 104 | #define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1) |
1fd182f0 PE |
105 | |
106 | /* True if the arithmetic type T is signed. */ | |
107 | #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) | |
108 | ||
109 | /* The maximum and minimum values for the integer type T. These | |
110 | macros have undefined behavior if T is signed and has padding bits. | |
111 | If this is a problem for you, please let us know how to fix it for | |
112 | your host. */ | |
113 | #define TYPE_MINIMUM(t) \ | |
114 | ((t) (! TYPE_SIGNED (t) \ | |
115 | ? (t) 0 \ | |
3de84ad9 | 116 | : ~ TYPE_MAXIMUM (t))) |
1fd182f0 PE |
117 | #define TYPE_MAXIMUM(t) \ |
118 | ((t) (! TYPE_SIGNED (t) \ | |
119 | ? (t) -1 \ | |
3de84ad9 | 120 | : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1))) |
1fd182f0 PE |
121 | |
122 | #ifndef TIME_T_MIN | |
123 | # define TIME_T_MIN TYPE_MINIMUM (time_t) | |
124 | #endif | |
125 | #ifndef TIME_T_MAX | |
126 | # define TIME_T_MAX TYPE_MAXIMUM (time_t) | |
127 | #endif | |
128 | #define TIME_T_MIDPOINT (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1) | |
129 | ||
1fd182f0 | 130 | verify (time_t_is_integer, TYPE_IS_INTEGER (time_t)); |
3de84ad9 PE |
131 | verify (twos_complement_arithmetic, |
132 | (TYPE_TWOS_COMPLEMENT (int) | |
133 | && TYPE_TWOS_COMPLEMENT (long_int) | |
134 | && TYPE_TWOS_COMPLEMENT (time_t))); | |
1fd182f0 PE |
135 | |
136 | #define EPOCH_YEAR 1970 | |
137 | #define TM_YEAR_BASE 1900 | |
138 | verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0); | |
139 | ||
140 | /* Return 1 if YEAR + TM_YEAR_BASE is a leap year. */ | |
141 | static inline int | |
3de84ad9 | 142 | leapyear (long_int year) |
1fd182f0 PE |
143 | { |
144 | /* Don't add YEAR to TM_YEAR_BASE, as that might overflow. | |
145 | Also, work even if YEAR is negative. */ | |
146 | return | |
147 | ((year & 3) == 0 | |
148 | && (year % 100 != 0 | |
149 | || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3))); | |
150 | } | |
151 | ||
152 | /* How many days come before each month (0-12). */ | |
153 | #ifndef _LIBC | |
154 | static | |
155 | #endif | |
156 | const unsigned short int __mon_yday[2][13] = | |
157 | { | |
158 | /* Normal years. */ | |
159 | { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, | |
160 | /* Leap years. */ | |
161 | { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } | |
162 | }; | |
163 | ||
164 | ||
165 | #ifndef _LIBC | |
166 | /* Portable standalone applications should supply a <time.h> that | |
167 | declares a POSIX-compliant localtime_r, for the benefit of older | |
168 | implementations that lack localtime_r or have a nonstandard one. | |
169 | See the gnulib time_r module for one way to implement this. */ | |
170 | # undef __localtime_r | |
171 | # define __localtime_r localtime_r | |
172 | # define __mktime_internal mktime_internal | |
173 | # include "mktime-internal.h" | |
174 | #endif | |
175 | ||
3de84ad9 PE |
176 | /* Return 1 if the values A and B differ according to the rules for |
177 | tm_isdst: A and B differ if one is zero and the other positive. */ | |
178 | static int | |
179 | isdst_differ (int a, int b) | |
180 | { | |
181 | return (!a != !b) & (0 <= a) & (0 <= b); | |
182 | } | |
183 | ||
1fd182f0 PE |
184 | /* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) - |
185 | (YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks | |
186 | were not adjusted between the time stamps. | |
187 | ||
188 | The YEAR values uses the same numbering as TP->tm_year. Values | |
189 | need not be in the usual range. However, YEAR1 must not be less | |
190 | than 2 * INT_MIN or greater than 2 * INT_MAX. | |
191 | ||
192 | The result may overflow. It is the caller's responsibility to | |
193 | detect overflow. */ | |
194 | ||
195 | static inline time_t | |
3de84ad9 | 196 | ydhms_diff (long_int year1, long_int yday1, int hour1, int min1, int sec1, |
1fd182f0 PE |
197 | int year0, int yday0, int hour0, int min0, int sec0) |
198 | { | |
199 | verify (C99_integer_division, -1 / 2 == 0); | |
1fd182f0 PE |
200 | |
201 | /* Compute intervening leap days correctly even if year is negative. | |
202 | Take care to avoid integer overflow here. */ | |
203 | int a4 = SHR (year1, 2) + SHR (TM_YEAR_BASE, 2) - ! (year1 & 3); | |
204 | int b4 = SHR (year0, 2) + SHR (TM_YEAR_BASE, 2) - ! (year0 & 3); | |
205 | int a100 = a4 / 25 - (a4 % 25 < 0); | |
206 | int b100 = b4 / 25 - (b4 % 25 < 0); | |
207 | int a400 = SHR (a100, 2); | |
208 | int b400 = SHR (b100, 2); | |
209 | int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400); | |
210 | ||
211 | /* Compute the desired time in time_t precision. Overflow might | |
212 | occur here. */ | |
213 | time_t tyear1 = year1; | |
214 | time_t years = tyear1 - year0; | |
215 | time_t days = 365 * years + yday1 - yday0 + intervening_leap_days; | |
216 | time_t hours = 24 * days + hour1 - hour0; | |
217 | time_t minutes = 60 * hours + min1 - min0; | |
218 | time_t seconds = 60 * minutes + sec1 - sec0; | |
219 | return seconds; | |
220 | } | |
221 | ||
3de84ad9 PE |
222 | /* Return the average of A and B, even if A + B would overflow. */ |
223 | static time_t | |
224 | time_t_avg (time_t a, time_t b) | |
225 | { | |
226 | return SHR (a, 1) + SHR (b, 1) + (a & b & 1); | |
227 | } | |
228 | ||
229 | /* Return 1 if A + B does not overflow. If time_t is unsigned and if | |
230 | B's top bit is set, assume that the sum represents A - -B, and | |
231 | return 1 if the subtraction does not wrap around. */ | |
232 | static int | |
233 | time_t_add_ok (time_t a, time_t b) | |
234 | { | |
235 | if (! TYPE_SIGNED (time_t)) | |
236 | { | |
237 | time_t sum = a + b; | |
238 | return (sum < a) == (TIME_T_MIDPOINT <= b); | |
239 | } | |
240 | else if (WRAPV) | |
241 | { | |
242 | time_t sum = a + b; | |
243 | return (sum < a) == (b < 0); | |
244 | } | |
245 | else | |
246 | { | |
247 | time_t avg = time_t_avg (a, b); | |
248 | return TIME_T_MIN / 2 <= avg && avg <= TIME_T_MAX / 2; | |
249 | } | |
250 | } | |
251 | ||
252 | /* Return 1 if A + B does not overflow. */ | |
253 | static int | |
254 | time_t_int_add_ok (time_t a, int b) | |
255 | { | |
256 | verify (int_no_wider_than_time_t, INT_MAX <= TIME_T_MAX); | |
257 | if (WRAPV) | |
258 | { | |
259 | time_t sum = a + b; | |
260 | return (sum < a) == (b < 0); | |
261 | } | |
262 | else | |
263 | { | |
264 | int a_odd = a & 1; | |
265 | time_t avg = SHR (a, 1) + (SHR (b, 1) + (a_odd & b)); | |
266 | return TIME_T_MIN / 2 <= avg && avg <= TIME_T_MAX / 2; | |
267 | } | |
268 | } | |
1fd182f0 PE |
269 | |
270 | /* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC), | |
271 | assuming that *T corresponds to *TP and that no clock adjustments | |
272 | occurred between *TP and the desired time. | |
273 | If TP is null, return a value not equal to *T; this avoids false matches. | |
274 | If overflow occurs, yield the minimal or maximal value, except do not | |
275 | yield a value equal to *T. */ | |
276 | static time_t | |
3de84ad9 | 277 | guess_time_tm (long_int year, long_int yday, int hour, int min, int sec, |
1fd182f0 PE |
278 | const time_t *t, const struct tm *tp) |
279 | { | |
280 | if (tp) | |
281 | { | |
282 | time_t d = ydhms_diff (year, yday, hour, min, sec, | |
283 | tp->tm_year, tp->tm_yday, | |
284 | tp->tm_hour, tp->tm_min, tp->tm_sec); | |
3de84ad9 PE |
285 | if (time_t_add_ok (*t, d)) |
286 | return *t + d; | |
1fd182f0 PE |
287 | } |
288 | ||
289 | /* Overflow occurred one way or another. Return the nearest result | |
290 | that is actually in range, except don't report a zero difference | |
291 | if the actual difference is nonzero, as that would cause a false | |
292 | match; and don't oscillate between two values, as that would | |
293 | confuse the spring-forward gap detector. */ | |
294 | return (*t < TIME_T_MIDPOINT | |
295 | ? (*t <= TIME_T_MIN + 1 ? *t + 1 : TIME_T_MIN) | |
296 | : (TIME_T_MAX - 1 <= *t ? *t - 1 : TIME_T_MAX)); | |
297 | } | |
298 | ||
299 | /* Use CONVERT to convert *T to a broken down time in *TP. | |
300 | If *T is out of range for conversion, adjust it so that | |
301 | it is the nearest in-range value and then convert that. */ | |
302 | static struct tm * | |
303 | ranged_convert (struct tm *(*convert) (const time_t *, struct tm *), | |
304 | time_t *t, struct tm *tp) | |
305 | { | |
306 | struct tm *r = convert (t, tp); | |
307 | ||
308 | if (!r && *t) | |
309 | { | |
310 | time_t bad = *t; | |
311 | time_t ok = 0; | |
312 | ||
313 | /* BAD is a known unconvertible time_t, and OK is a known good one. | |
314 | Use binary search to narrow the range between BAD and OK until | |
315 | they differ by 1. */ | |
316 | while (bad != ok + (bad < 0 ? -1 : 1)) | |
317 | { | |
3de84ad9 | 318 | time_t mid = *t = time_t_avg (ok, bad); |
1fd182f0 PE |
319 | r = convert (t, tp); |
320 | if (r) | |
321 | ok = mid; | |
322 | else | |
323 | bad = mid; | |
324 | } | |
325 | ||
326 | if (!r && ok) | |
327 | { | |
328 | /* The last conversion attempt failed; | |
329 | revert to the most recent successful attempt. */ | |
330 | *t = ok; | |
331 | r = convert (t, tp); | |
332 | } | |
333 | } | |
334 | ||
335 | return r; | |
336 | } | |
337 | ||
338 | ||
339 | /* Convert *TP to a time_t value, inverting | |
340 | the monotonic and mostly-unit-linear conversion function CONVERT. | |
341 | Use *OFFSET to keep track of a guess at the offset of the result, | |
342 | compared to what the result would be for UTC without leap seconds. | |
343 | If *OFFSET's guess is correct, only one CONVERT call is needed. | |
344 | This function is external because it is used also by timegm.c. */ | |
345 | time_t | |
346 | __mktime_internal (struct tm *tp, | |
347 | struct tm *(*convert) (const time_t *, struct tm *), | |
348 | time_t *offset) | |
349 | { | |
350 | time_t t, gt, t0, t1, t2; | |
351 | struct tm tm; | |
352 | ||
353 | /* The maximum number of probes (calls to CONVERT) should be enough | |
354 | to handle any combinations of time zone rule changes, solar time, | |
355 | leap seconds, and oscillations around a spring-forward gap. | |
356 | POSIX.1 prohibits leap seconds, but some hosts have them anyway. */ | |
357 | int remaining_probes = 6; | |
358 | ||
359 | /* Time requested. Copy it in case CONVERT modifies *TP; this can | |
360 | occur if TP is localtime's returned value and CONVERT is localtime. */ | |
361 | int sec = tp->tm_sec; | |
362 | int min = tp->tm_min; | |
363 | int hour = tp->tm_hour; | |
364 | int mday = tp->tm_mday; | |
365 | int mon = tp->tm_mon; | |
366 | int year_requested = tp->tm_year; | |
3de84ad9 | 367 | int isdst = tp->tm_isdst; |
1fd182f0 PE |
368 | |
369 | /* 1 if the previous probe was DST. */ | |
370 | int dst2; | |
371 | ||
372 | /* Ensure that mon is in range, and set year accordingly. */ | |
373 | int mon_remainder = mon % 12; | |
374 | int negative_mon_remainder = mon_remainder < 0; | |
375 | int mon_years = mon / 12 - negative_mon_remainder; | |
3de84ad9 PE |
376 | long_int lyear_requested = year_requested; |
377 | long_int year = lyear_requested + mon_years; | |
1fd182f0 PE |
378 | |
379 | /* The other values need not be in range: | |
380 | the remaining code handles minor overflows correctly, | |
381 | assuming int and time_t arithmetic wraps around. | |
382 | Major overflows are caught at the end. */ | |
383 | ||
384 | /* Calculate day of year from year, month, and day of month. | |
385 | The result need not be in range. */ | |
386 | int mon_yday = ((__mon_yday[leapyear (year)] | |
387 | [mon_remainder + 12 * negative_mon_remainder]) | |
388 | - 1); | |
3de84ad9 PE |
389 | long_int lmday = mday; |
390 | long_int yday = mon_yday + lmday; | |
1fd182f0 PE |
391 | |
392 | time_t guessed_offset = *offset; | |
393 | ||
394 | int sec_requested = sec; | |
395 | ||
396 | if (LEAP_SECONDS_POSSIBLE) | |
397 | { | |
398 | /* Handle out-of-range seconds specially, | |
399 | since ydhms_tm_diff assumes every minute has 60 seconds. */ | |
400 | if (sec < 0) | |
401 | sec = 0; | |
402 | if (59 < sec) | |
403 | sec = 59; | |
404 | } | |
405 | ||
406 | /* Invert CONVERT by probing. First assume the same offset as last | |
407 | time. */ | |
408 | ||
409 | t0 = ydhms_diff (year, yday, hour, min, sec, | |
410 | EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset); | |
411 | ||
412 | if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3) | |
413 | { | |
414 | /* time_t isn't large enough to rule out overflows, so check | |
415 | for major overflows. A gross check suffices, since if t0 | |
416 | has overflowed, it is off by a multiple of TIME_T_MAX - | |
417 | TIME_T_MIN + 1. So ignore any component of the difference | |
418 | that is bounded by a small value. */ | |
419 | ||
420 | /* Approximate log base 2 of the number of time units per | |
421 | biennium. A biennium is 2 years; use this unit instead of | |
422 | years to avoid integer overflow. For example, 2 average | |
423 | Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds, | |
424 | which is 63113904 seconds, and rint (log2 (63113904)) is | |
425 | 26. */ | |
426 | int ALOG2_SECONDS_PER_BIENNIUM = 26; | |
427 | int ALOG2_MINUTES_PER_BIENNIUM = 20; | |
428 | int ALOG2_HOURS_PER_BIENNIUM = 14; | |
429 | int ALOG2_DAYS_PER_BIENNIUM = 10; | |
430 | int LOG2_YEARS_PER_BIENNIUM = 1; | |
431 | ||
432 | int approx_requested_biennia = | |
433 | (SHR (year_requested, LOG2_YEARS_PER_BIENNIUM) | |
434 | - SHR (EPOCH_YEAR - TM_YEAR_BASE, LOG2_YEARS_PER_BIENNIUM) | |
435 | + SHR (mday, ALOG2_DAYS_PER_BIENNIUM) | |
436 | + SHR (hour, ALOG2_HOURS_PER_BIENNIUM) | |
437 | + SHR (min, ALOG2_MINUTES_PER_BIENNIUM) | |
438 | + (LEAP_SECONDS_POSSIBLE | |
439 | ? 0 | |
440 | : SHR (sec, ALOG2_SECONDS_PER_BIENNIUM))); | |
441 | ||
442 | int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM); | |
443 | int diff = approx_biennia - approx_requested_biennia; | |
3de84ad9 | 444 | int abs_diff = diff < 0 ? -1 - diff : diff; |
1fd182f0 | 445 | |
3de84ad9 | 446 | /* IRIX 4.0.5 cc miscalculates TIME_T_MIN / 3: it erroneously |
1fd182f0 PE |
447 | gives a positive value of 715827882. Setting a variable |
448 | first then doing math on it seems to work. | |
449 | (ghazi@caip.rutgers.edu) */ | |
450 | time_t time_t_max = TIME_T_MAX; | |
451 | time_t time_t_min = TIME_T_MIN; | |
452 | time_t overflow_threshold = | |
453 | (time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM; | |
454 | ||
455 | if (overflow_threshold < abs_diff) | |
456 | { | |
457 | /* Overflow occurred. Try repairing it; this might work if | |
458 | the time zone offset is enough to undo the overflow. */ | |
459 | time_t repaired_t0 = -1 - t0; | |
460 | approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM); | |
461 | diff = approx_biennia - approx_requested_biennia; | |
3de84ad9 | 462 | abs_diff = diff < 0 ? -1 - diff : diff; |
1fd182f0 PE |
463 | if (overflow_threshold < abs_diff) |
464 | return -1; | |
465 | guessed_offset += repaired_t0 - t0; | |
466 | t0 = repaired_t0; | |
467 | } | |
468 | } | |
469 | ||
470 | /* Repeatedly use the error to improve the guess. */ | |
471 | ||
472 | for (t = t1 = t2 = t0, dst2 = 0; | |
473 | (gt = guess_time_tm (year, yday, hour, min, sec, &t, | |
474 | ranged_convert (convert, &t, &tm)), | |
475 | t != gt); | |
476 | t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0) | |
477 | if (t == t1 && t != t2 | |
478 | && (tm.tm_isdst < 0 | |
479 | || (isdst < 0 | |
480 | ? dst2 <= (tm.tm_isdst != 0) | |
481 | : (isdst != 0) != (tm.tm_isdst != 0)))) | |
482 | /* We can't possibly find a match, as we are oscillating | |
483 | between two values. The requested time probably falls | |
484 | within a spring-forward gap of size GT - T. Follow the common | |
485 | practice in this case, which is to return a time that is GT - T | |
486 | away from the requested time, preferring a time whose | |
487 | tm_isdst differs from the requested value. (If no tm_isdst | |
488 | was requested and only one of the two values has a nonzero | |
489 | tm_isdst, prefer that value.) In practice, this is more | |
490 | useful than returning -1. */ | |
491 | goto offset_found; | |
492 | else if (--remaining_probes == 0) | |
493 | return -1; | |
494 | ||
495 | /* We have a match. Check whether tm.tm_isdst has the requested | |
496 | value, if any. */ | |
3de84ad9 | 497 | if (isdst_differ (isdst, tm.tm_isdst)) |
1fd182f0 PE |
498 | { |
499 | /* tm.tm_isdst has the wrong value. Look for a neighboring | |
500 | time with the right value, and use its UTC offset. | |
501 | ||
502 | Heuristic: probe the adjacent timestamps in both directions, | |
503 | looking for the desired isdst. This should work for all real | |
504 | time zone histories in the tz database. */ | |
505 | ||
506 | /* Distance between probes when looking for a DST boundary. In | |
507 | tzdata2003a, the shortest period of DST is 601200 seconds | |
508 | (e.g., America/Recife starting 2000-10-08 01:00), and the | |
509 | shortest period of non-DST surrounded by DST is 694800 | |
510 | seconds (Africa/Tunis starting 1943-04-17 01:00). Use the | |
511 | minimum of these two values, so we don't miss these short | |
512 | periods when probing. */ | |
513 | int stride = 601200; | |
514 | ||
515 | /* The longest period of DST in tzdata2003a is 536454000 seconds | |
516 | (e.g., America/Jujuy starting 1946-10-01 01:00). The longest | |
517 | period of non-DST is much longer, but it makes no real sense | |
518 | to search for more than a year of non-DST, so use the DST | |
519 | max. */ | |
520 | int duration_max = 536454000; | |
521 | ||
522 | /* Search in both directions, so the maximum distance is half | |
523 | the duration; add the stride to avoid off-by-1 problems. */ | |
524 | int delta_bound = duration_max / 2 + stride; | |
525 | ||
526 | int delta, direction; | |
527 | ||
528 | for (delta = stride; delta < delta_bound; delta += stride) | |
529 | for (direction = -1; direction <= 1; direction += 2) | |
3de84ad9 PE |
530 | if (time_t_int_add_ok (t, delta * direction)) |
531 | { | |
532 | time_t ot = t + delta * direction; | |
533 | struct tm otm; | |
534 | ranged_convert (convert, &ot, &otm); | |
535 | if (! isdst_differ (isdst, otm.tm_isdst)) | |
536 | { | |
537 | /* We found the desired tm_isdst. | |
538 | Extrapolate back to the desired time. */ | |
539 | t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm); | |
540 | ranged_convert (convert, &t, &tm); | |
541 | goto offset_found; | |
542 | } | |
543 | } | |
1fd182f0 PE |
544 | } |
545 | ||
546 | offset_found: | |
547 | *offset = guessed_offset + t - t0; | |
548 | ||
549 | if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec) | |
550 | { | |
551 | /* Adjust time to reflect the tm_sec requested, not the normalized value. | |
552 | Also, repair any damage from a false match due to a leap second. */ | |
553 | int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec; | |
3de84ad9 PE |
554 | if (! time_t_int_add_ok (t, sec_requested)) |
555 | return -1; | |
1fd182f0 | 556 | t1 = t + sec_requested; |
3de84ad9 PE |
557 | if (! time_t_int_add_ok (t1, sec_adjustment)) |
558 | return -1; | |
1fd182f0 | 559 | t2 = t1 + sec_adjustment; |
3de84ad9 | 560 | if (! convert (&t2, &tm)) |
1fd182f0 PE |
561 | return -1; |
562 | t = t2; | |
563 | } | |
564 | ||
565 | *tp = tm; | |
566 | return t; | |
567 | } | |
568 | ||
569 | ||
570 | /* FIXME: This should use a signed type wide enough to hold any UTC | |
571 | offset in seconds. 'int' should be good enough for GNU code. We | |
572 | can't fix this unilaterally though, as other modules invoke | |
573 | __mktime_internal. */ | |
574 | static time_t localtime_offset; | |
575 | ||
576 | /* Convert *TP to a time_t value. */ | |
577 | time_t | |
578 | mktime (struct tm *tp) | |
579 | { | |
580 | #ifdef _LIBC | |
581 | /* POSIX.1 8.1.1 requires that whenever mktime() is called, the | |
582 | time zone names contained in the external variable `tzname' shall | |
583 | be set as if the tzset() function had been called. */ | |
584 | __tzset (); | |
585 | #endif | |
586 | ||
587 | return __mktime_internal (tp, __localtime_r, &localtime_offset); | |
588 | } | |
589 | ||
590 | #ifdef weak_alias | |
591 | weak_alias (mktime, timelocal) | |
592 | #endif | |
593 | ||
594 | #ifdef _LIBC | |
595 | libc_hidden_def (mktime) | |
596 | libc_hidden_weak (timelocal) | |
597 | #endif | |
598 | \f | |
599 | #if DEBUG | |
600 | ||
601 | static int | |
602 | not_equal_tm (const struct tm *a, const struct tm *b) | |
603 | { | |
604 | return ((a->tm_sec ^ b->tm_sec) | |
605 | | (a->tm_min ^ b->tm_min) | |
606 | | (a->tm_hour ^ b->tm_hour) | |
607 | | (a->tm_mday ^ b->tm_mday) | |
608 | | (a->tm_mon ^ b->tm_mon) | |
609 | | (a->tm_year ^ b->tm_year) | |
610 | | (a->tm_yday ^ b->tm_yday) | |
3de84ad9 | 611 | | isdst_differ (a->tm_isdst, b->tm_isdst)); |
1fd182f0 PE |
612 | } |
613 | ||
614 | static void | |
615 | print_tm (const struct tm *tp) | |
616 | { | |
617 | if (tp) | |
618 | printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d", | |
619 | tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday, | |
620 | tp->tm_hour, tp->tm_min, tp->tm_sec, | |
621 | tp->tm_yday, tp->tm_wday, tp->tm_isdst); | |
622 | else | |
623 | printf ("0"); | |
624 | } | |
625 | ||
626 | static int | |
627 | check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt) | |
628 | { | |
629 | if (tk != tl || !lt || not_equal_tm (&tmk, lt)) | |
630 | { | |
631 | printf ("mktime ("); | |
632 | print_tm (lt); | |
633 | printf (")\nyields ("); | |
634 | print_tm (&tmk); | |
635 | printf (") == %ld, should be %ld\n", (long int) tk, (long int) tl); | |
636 | return 1; | |
637 | } | |
638 | ||
639 | return 0; | |
640 | } | |
641 | ||
642 | int | |
643 | main (int argc, char **argv) | |
644 | { | |
645 | int status = 0; | |
646 | struct tm tm, tmk, tml; | |
647 | struct tm *lt; | |
648 | time_t tk, tl, tl1; | |
649 | char trailer; | |
650 | ||
651 | if ((argc == 3 || argc == 4) | |
652 | && (sscanf (argv[1], "%d-%d-%d%c", | |
653 | &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer) | |
654 | == 3) | |
655 | && (sscanf (argv[2], "%d:%d:%d%c", | |
656 | &tm.tm_hour, &tm.tm_min, &tm.tm_sec, &trailer) | |
657 | == 3)) | |
658 | { | |
659 | tm.tm_year -= TM_YEAR_BASE; | |
660 | tm.tm_mon--; | |
661 | tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]); | |
662 | tmk = tm; | |
663 | tl = mktime (&tmk); | |
664 | lt = localtime (&tl); | |
665 | if (lt) | |
666 | { | |
667 | tml = *lt; | |
668 | lt = &tml; | |
669 | } | |
670 | printf ("mktime returns %ld == ", (long int) tl); | |
671 | print_tm (&tmk); | |
672 | printf ("\n"); | |
673 | status = check_result (tl, tmk, tl, lt); | |
674 | } | |
675 | else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0)) | |
676 | { | |
677 | time_t from = atol (argv[1]); | |
678 | time_t by = atol (argv[2]); | |
679 | time_t to = atol (argv[3]); | |
680 | ||
681 | if (argc == 4) | |
682 | for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1) | |
683 | { | |
684 | lt = localtime (&tl); | |
685 | if (lt) | |
686 | { | |
687 | tmk = tml = *lt; | |
688 | tk = mktime (&tmk); | |
689 | status |= check_result (tk, tmk, tl, &tml); | |
690 | } | |
691 | else | |
692 | { | |
693 | printf ("localtime (%ld) yields 0\n", (long int) tl); | |
694 | status = 1; | |
695 | } | |
696 | tl1 = tl + by; | |
697 | if ((tl1 < tl) != (by < 0)) | |
698 | break; | |
699 | } | |
700 | else | |
701 | for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1) | |
702 | { | |
703 | /* Null benchmark. */ | |
704 | lt = localtime (&tl); | |
705 | if (lt) | |
706 | { | |
707 | tmk = tml = *lt; | |
708 | tk = tl; | |
709 | status |= check_result (tk, tmk, tl, &tml); | |
710 | } | |
711 | else | |
712 | { | |
713 | printf ("localtime (%ld) yields 0\n", (long int) tl); | |
714 | status = 1; | |
715 | } | |
716 | tl1 = tl + by; | |
717 | if ((tl1 < tl) != (by < 0)) | |
718 | break; | |
719 | } | |
720 | } | |
721 | else | |
722 | printf ("Usage:\ | |
723 | \t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\ | |
724 | \t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\ | |
725 | \t%s FROM BY TO - # Do not test those values (for benchmark).\n", | |
726 | argv[0], argv[0], argv[0]); | |
727 | ||
728 | return status; | |
729 | } | |
730 | ||
731 | #endif /* DEBUG */ | |
732 | \f | |
733 | /* | |
734 | Local Variables: | |
3de84ad9 | 735 | compile-command: "gcc -DDEBUG -I. -Wall -W -O2 -g mktime.c -o mktime" |
1fd182f0 PE |
736 | End: |
737 | */ |