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6226efbd | 1 | /* Convert a 'struct tm' to a time_t value. |
581c785b | 2 | Copyright (C) 1993-2022 Free Software Foundation, Inc. |
5290baf0 | 3 | This file is part of the GNU C Library. |
41aba3d7 | 4 | Contributed by Paul Eggert <eggert@twinsun.com>. |
28f540f4 | 5 | |
5290baf0 | 6 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
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. | |
28f540f4 | 10 | |
5290baf0 UD |
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 | |
41bdb6e2 | 14 | Lesser General Public License for more details. |
28f540f4 | 15 | |
41bdb6e2 | 16 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 17 | License along with the GNU C Library; if not, see |
8e6fd2bd | 18 | <https://www.gnu.org/licenses/>. */ |
28f540f4 | 19 | |
8e6fd2bd PE |
20 | /* The following macros influence what gets defined when this file is compiled: |
21 | ||
22 | Macro/expression Which gnulib module This compilation unit | |
23 | should define | |
24 | ||
25 | _LIBC (glibc proper) mktime | |
26 | ||
27 | NEED_MKTIME_WORKING mktime rpl_mktime | |
28 | || NEED_MKTIME_WINDOWS | |
29 | ||
30 | NEED_MKTIME_INTERNAL mktime-internal mktime_internal | |
8e6fd2bd PE |
31 | */ |
32 | ||
5d8af156 | 33 | #ifndef _LIBC |
de20b81a | 34 | # include <libc-config.h> |
28f540f4 RM |
35 | #endif |
36 | ||
80fd7387 | 37 | /* Assume that leap seconds are possible, unless told otherwise. |
6226efbd | 38 | If the host has a 'zic' command with a '-L leapsecondfilename' option, |
80fd7387 RM |
39 | then it supports leap seconds; otherwise it probably doesn't. */ |
40 | #ifndef LEAP_SECONDS_POSSIBLE | |
9c2322bc | 41 | # define LEAP_SECONDS_POSSIBLE 1 |
80fd7387 RM |
42 | #endif |
43 | ||
28f540f4 RM |
44 | #include <time.h> |
45 | ||
de20b81a | 46 | #include <errno.h> |
85e07670 | 47 | #include <limits.h> |
8e6fd2bd PE |
48 | #include <stdbool.h> |
49 | #include <stdlib.h> | |
50 | #include <string.h> | |
28f540f4 | 51 | |
8e6fd2bd PE |
52 | #include <intprops.h> |
53 | #include <verify.h> | |
9b5204dd | 54 | |
8e6fd2bd PE |
55 | #ifndef NEED_MKTIME_INTERNAL |
56 | # define NEED_MKTIME_INTERNAL 0 | |
57 | #endif | |
58 | #ifndef NEED_MKTIME_WINDOWS | |
59 | # define NEED_MKTIME_WINDOWS 0 | |
60 | #endif | |
61 | #ifndef NEED_MKTIME_WORKING | |
5d8af156 | 62 | # define NEED_MKTIME_WORKING 0 |
8e6fd2bd PE |
63 | #endif |
64 | ||
65 | #include "mktime-internal.h" | |
66 | ||
5a580643 | 67 | #if !defined _LIBC && (NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS) |
8e6fd2bd PE |
68 | static void |
69 | my_tzset (void) | |
70 | { | |
71 | # if NEED_MKTIME_WINDOWS | |
72 | /* Rectify the value of the environment variable TZ. | |
73 | There are four possible kinds of such values: | |
74 | - Traditional US time zone names, e.g. "PST8PDT". Syntax: see | |
78919d38 | 75 | <https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/tzset> |
8e6fd2bd PE |
76 | - Time zone names based on geography, that contain one or more |
77 | slashes, e.g. "Europe/Moscow". | |
78 | - Time zone names based on geography, without slashes, e.g. | |
79 | "Singapore". | |
80 | - Time zone names that contain explicit DST rules. Syntax: see | |
f8042536 | 81 | <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03> |
8e6fd2bd PE |
82 | The Microsoft CRT understands only the first kind. It produces incorrect |
83 | results if the value of TZ is of the other kinds. | |
84 | But in a Cygwin environment, /etc/profile.d/tzset.sh sets TZ to a value | |
85 | of the second kind for most geographies, or of the first kind in a few | |
86 | other geographies. If it is of the second kind, neutralize it. For the | |
87 | Microsoft CRT, an absent or empty TZ means the time zone that the user | |
88 | has set in the Windows Control Panel. | |
89 | If the value of TZ is of the third or fourth kind -- Cygwin programs | |
90 | understand these syntaxes as well --, it does not matter whether we | |
91 | neutralize it or not, since these values occur only when a Cygwin user | |
92 | has set TZ explicitly; this case is 1. rare and 2. under the user's | |
93 | responsibility. */ | |
94 | const char *tz = getenv ("TZ"); | |
95 | if (tz != NULL && strchr (tz, '/') != NULL) | |
96 | _putenv ("TZ="); | |
82a1ec85 | 97 | # else |
8e6fd2bd | 98 | tzset (); |
62bdf9a6 | 99 | # endif |
8e6fd2bd PE |
100 | } |
101 | # undef __tzset | |
102 | # define __tzset() my_tzset () | |
62bdf9a6 PE |
103 | #endif |
104 | ||
8e6fd2bd PE |
105 | #if defined _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_INTERNAL |
106 | ||
107 | /* A signed type that can represent an integer number of years | |
efbdddc3 | 108 | multiplied by four times the number of seconds in a year. It is |
8e6fd2bd | 109 | needed when converting a tm_year value times the number of seconds |
efbdddc3 | 110 | in a year. The factor of four comes because these products need |
8e6fd2bd | 111 | to be subtracted from each other, and sometimes with an offset |
efbdddc3 PE |
112 | added to them, and then with another timestamp added, without |
113 | worrying about overflow. | |
8e6fd2bd | 114 | |
20aa5819 PE |
115 | Much of the code uses long_int to represent __time64_t values, to |
116 | lessen the hassle of dealing with platforms where __time64_t is | |
8e6fd2bd | 117 | unsigned, and because long_int should suffice to represent all |
20aa5819 PE |
118 | __time64_t values that mktime can generate even on platforms where |
119 | __time64_t is wider than the int components of struct tm. */ | |
f04dfbc2 | 120 | |
efbdddc3 | 121 | #if INT_MAX <= LONG_MAX / 4 / 366 / 24 / 60 / 60 |
f04dfbc2 PE |
122 | typedef long int long_int; |
123 | #else | |
124 | typedef long long int long_int; | |
125 | #endif | |
efbdddc3 | 126 | verify (INT_MAX <= TYPE_MAXIMUM (long_int) / 4 / 366 / 24 / 60 / 60); |
f04dfbc2 | 127 | |
1c67fabd | 128 | /* Shift A right by B bits portably, by dividing A by 2**B and |
8e6fd2bd PE |
129 | truncating towards minus infinity. B should be in the range 0 <= B |
130 | <= LONG_INT_BITS - 2, where LONG_INT_BITS is the number of useful | |
131 | bits in a long_int. LONG_INT_BITS is at least 32. | |
1c67fabd RM |
132 | |
133 | ISO C99 says that A >> B is implementation-defined if A < 0. Some | |
134 | implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift | |
135 | right in the usual way when A < 0, so SHR falls back on division if | |
136 | ordinary A >> B doesn't seem to be the usual signed shift. */ | |
28f540f4 | 137 | |
8e6fd2bd PE |
138 | static long_int |
139 | shr (long_int a, int b) | |
140 | { | |
141 | long_int one = 1; | |
142 | return (-one >> 1 == -1 | |
143 | ? a >> b | |
db10cd9e | 144 | : (a + (a < 0)) / (one << b) - (a < 0)); |
8e6fd2bd PE |
145 | } |
146 | ||
20aa5819 | 147 | /* Bounds for the intersection of __time64_t and long_int. */ |
8e6fd2bd PE |
148 | |
149 | static long_int const mktime_min | |
20aa5819 PE |
150 | = ((TYPE_SIGNED (__time64_t) |
151 | && TYPE_MINIMUM (__time64_t) < TYPE_MINIMUM (long_int)) | |
152 | ? TYPE_MINIMUM (long_int) : TYPE_MINIMUM (__time64_t)); | |
8e6fd2bd | 153 | static long_int const mktime_max |
20aa5819 PE |
154 | = (TYPE_MAXIMUM (long_int) < TYPE_MAXIMUM (__time64_t) |
155 | ? TYPE_MAXIMUM (long_int) : TYPE_MAXIMUM (__time64_t)); | |
a28a0500 | 156 | |
80fd7387 | 157 | #define EPOCH_YEAR 1970 |
a28a0500 | 158 | #define TM_YEAR_BASE 1900 |
8e6fd2bd | 159 | verify (TM_YEAR_BASE % 100 == 0); |
28f540f4 | 160 | |
8e6fd2bd PE |
161 | /* Is YEAR + TM_YEAR_BASE a leap year? */ |
162 | static bool | |
f04dfbc2 | 163 | leapyear (long_int year) |
72035294 RM |
164 | { |
165 | /* Don't add YEAR to TM_YEAR_BASE, as that might overflow. | |
166 | Also, work even if YEAR is negative. */ | |
167 | return | |
168 | ((year & 3) == 0 | |
169 | && (year % 100 != 0 | |
170 | || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3))); | |
171 | } | |
28f540f4 | 172 | |
80fd7387 | 173 | /* How many days come before each month (0-12). */ |
8592ae92 UD |
174 | #ifndef _LIBC |
175 | static | |
176 | #endif | |
80fd7387 RM |
177 | const unsigned short int __mon_yday[2][13] = |
178 | { | |
179 | /* Normal years. */ | |
180 | { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, | |
181 | /* Leap years. */ | |
182 | { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } | |
183 | }; | |
28f540f4 | 184 | |
28f540f4 | 185 | |
8e6fd2bd PE |
186 | /* Do the values A and B differ according to the rules for tm_isdst? |
187 | A and B differ if one is zero and the other positive. */ | |
188 | static bool | |
ce73d683 PE |
189 | isdst_differ (int a, int b) |
190 | { | |
191 | return (!a != !b) && (0 <= a) && (0 <= b); | |
192 | } | |
193 | ||
e507cc56 RM |
194 | /* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) - |
195 | (YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks | |
8e6fd2bd | 196 | were not adjusted between the timestamps. |
80fd7387 | 197 | |
e507cc56 | 198 | The YEAR values uses the same numbering as TP->tm_year. Values |
efbdddc3 PE |
199 | need not be in the usual range. However, YEAR1 - YEAR0 must not |
200 | overflow even when multiplied by three times the number of seconds | |
201 | in a year, and likewise for YDAY1 - YDAY0 and three times the | |
202 | number of seconds in a day. */ | |
e507cc56 | 203 | |
8e6fd2bd | 204 | static long_int |
f04dfbc2 | 205 | ydhms_diff (long_int year1, long_int yday1, int hour1, int min1, int sec1, |
e507cc56 RM |
206 | int year0, int yday0, int hour0, int min0, int sec0) |
207 | { | |
8e6fd2bd | 208 | verify (-1 / 2 == 0); |
e507cc56 RM |
209 | |
210 | /* Compute intervening leap days correctly even if year is negative. | |
211 | Take care to avoid integer overflow here. */ | |
8e6fd2bd PE |
212 | int a4 = shr (year1, 2) + shr (TM_YEAR_BASE, 2) - ! (year1 & 3); |
213 | int b4 = shr (year0, 2) + shr (TM_YEAR_BASE, 2) - ! (year0 & 3); | |
db10cd9e PE |
214 | int a100 = (a4 + (a4 < 0)) / 25 - (a4 < 0); |
215 | int b100 = (b4 + (b4 < 0)) / 25 - (b4 < 0); | |
8e6fd2bd PE |
216 | int a400 = shr (a100, 2); |
217 | int b400 = shr (b100, 2); | |
e507cc56 RM |
218 | int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400); |
219 | ||
8e6fd2bd PE |
220 | /* Compute the desired time without overflowing. */ |
221 | long_int years = year1 - year0; | |
222 | long_int days = 365 * years + yday1 - yday0 + intervening_leap_days; | |
223 | long_int hours = 24 * days + hour1 - hour0; | |
224 | long_int minutes = 60 * hours + min1 - min0; | |
225 | long_int seconds = 60 * minutes + sec1 - sec0; | |
e507cc56 RM |
226 | return seconds; |
227 | } | |
228 | ||
8e6fd2bd PE |
229 | /* Return the average of A and B, even if A + B would overflow. |
230 | Round toward positive infinity. */ | |
231 | static long_int | |
232 | long_int_avg (long_int a, long_int b) | |
62bdf9a6 | 233 | { |
8e6fd2bd | 234 | return shr (a, 1) + shr (b, 1) + ((a | b) & 1); |
62bdf9a6 | 235 | } |
e507cc56 | 236 | |
86aece3b PE |
237 | /* Return a long_int value corresponding to (YEAR-YDAY HOUR:MIN:SEC) |
238 | minus *TP seconds, assuming no clock adjustments occurred between | |
239 | the two timestamps. | |
240 | ||
8e6fd2bd PE |
241 | YEAR and YDAY must not be so large that multiplying them by three times the |
242 | number of seconds in a year (or day, respectively) would overflow long_int. | |
86aece3b | 243 | *TP should be in the usual range. */ |
8e6fd2bd | 244 | static long_int |
86aece3b PE |
245 | tm_diff (long_int year, long_int yday, int hour, int min, int sec, |
246 | struct tm const *tp) | |
80fd7387 | 247 | { |
86aece3b PE |
248 | return ydhms_diff (year, yday, hour, min, sec, |
249 | tp->tm_year, tp->tm_yday, | |
250 | tp->tm_hour, tp->tm_min, tp->tm_sec); | |
8e6fd2bd PE |
251 | } |
252 | ||
253 | /* Use CONVERT to convert T to a struct tm value in *TM. T must be in | |
20aa5819 | 254 | range for __time64_t. Return TM if successful, NULL (setting errno) on |
86aece3b | 255 | failure. */ |
8e6fd2bd | 256 | static struct tm * |
20aa5819 | 257 | convert_time (struct tm *(*convert) (const __time64_t *, struct tm *), |
8e6fd2bd PE |
258 | long_int t, struct tm *tm) |
259 | { | |
20aa5819 | 260 | __time64_t x = t; |
8e6fd2bd | 261 | return convert (&x, tm); |
80fd7387 RM |
262 | } |
263 | ||
fe0ec73e UD |
264 | /* Use CONVERT to convert *T to a broken down time in *TP. |
265 | If *T is out of range for conversion, adjust it so that | |
8e6fd2bd | 266 | it is the nearest in-range value and then convert that. |
20aa5819 | 267 | A value is in range if it fits in both __time64_t and long_int. |
86aece3b | 268 | Return TP on success, NULL (setting errno) on failure. */ |
fe0ec73e | 269 | static struct tm * |
20aa5819 | 270 | ranged_convert (struct tm *(*convert) (const __time64_t *, struct tm *), |
8e6fd2bd | 271 | long_int *t, struct tm *tp) |
fe0ec73e | 272 | { |
86aece3b PE |
273 | long_int t1 = (*t < mktime_min ? mktime_min |
274 | : *t <= mktime_max ? *t : mktime_max); | |
275 | struct tm *r = convert_time (convert, t1, tp); | |
276 | if (r) | |
fe0ec73e | 277 | { |
86aece3b PE |
278 | *t = t1; |
279 | return r; | |
280 | } | |
281 | if (errno != EOVERFLOW) | |
282 | return NULL; | |
fe0ec73e | 283 | |
86aece3b PE |
284 | long_int bad = t1; |
285 | long_int ok = 0; | |
286 | struct tm oktm; oktm.tm_sec = -1; | |
f6b3331b | 287 | |
86aece3b PE |
288 | /* BAD is a known out-of-range value, and OK is a known in-range one. |
289 | Use binary search to narrow the range between BAD and OK until | |
290 | they differ by 1. */ | |
291 | while (true) | |
292 | { | |
293 | long_int mid = long_int_avg (ok, bad); | |
294 | if (mid == ok || mid == bad) | |
295 | break; | |
296 | if (convert_time (convert, mid, tp)) | |
297 | ok = mid, oktm = *tp; | |
298 | else if (errno != EOVERFLOW) | |
299 | return NULL; | |
300 | else | |
301 | bad = mid; | |
fe0ec73e UD |
302 | } |
303 | ||
86aece3b PE |
304 | if (oktm.tm_sec < 0) |
305 | return NULL; | |
306 | *t = ok; | |
307 | *tp = oktm; | |
308 | return tp; | |
fe0ec73e UD |
309 | } |
310 | ||
311 | ||
20aa5819 | 312 | /* Convert *TP to a __time64_t value, inverting |
80fd7387 RM |
313 | the monotonic and mostly-unit-linear conversion function CONVERT. |
314 | Use *OFFSET to keep track of a guess at the offset of the result, | |
315 | compared to what the result would be for UTC without leap seconds. | |
e507cc56 | 316 | If *OFFSET's guess is correct, only one CONVERT call is needed. |
de20b81a PE |
317 | If successful, set *TP to the canonicalized struct tm; |
318 | otherwise leave *TP alone, return ((time_t) -1) and set errno. | |
e507cc56 | 319 | This function is external because it is used also by timegm.c. */ |
20aa5819 | 320 | __time64_t |
eda78eec | 321 | __mktime_internal (struct tm *tp, |
20aa5819 | 322 | struct tm *(*convert) (const __time64_t *, struct tm *), |
8e6fd2bd | 323 | mktime_offset_t *offset) |
28f540f4 | 324 | { |
80fd7387 RM |
325 | struct tm tm; |
326 | ||
327 | /* The maximum number of probes (calls to CONVERT) should be enough | |
328 | to handle any combinations of time zone rule changes, solar time, | |
25b3b17b UD |
329 | leap seconds, and oscillations around a spring-forward gap. |
330 | POSIX.1 prohibits leap seconds, but some hosts have them anyway. */ | |
331 | int remaining_probes = 6; | |
80fd7387 RM |
332 | |
333 | /* Time requested. Copy it in case CONVERT modifies *TP; this can | |
334 | occur if TP is localtime's returned value and CONVERT is localtime. */ | |
335 | int sec = tp->tm_sec; | |
336 | int min = tp->tm_min; | |
337 | int hour = tp->tm_hour; | |
338 | int mday = tp->tm_mday; | |
339 | int mon = tp->tm_mon; | |
340 | int year_requested = tp->tm_year; | |
ce73d683 | 341 | int isdst = tp->tm_isdst; |
80fd7387 | 342 | |
b5ef404e | 343 | /* 1 if the previous probe was DST. */ |
86aece3b | 344 | int dst2 = 0; |
b5ef404e | 345 | |
80fd7387 RM |
346 | /* Ensure that mon is in range, and set year accordingly. */ |
347 | int mon_remainder = mon % 12; | |
348 | int negative_mon_remainder = mon_remainder < 0; | |
349 | int mon_years = mon / 12 - negative_mon_remainder; | |
f04dfbc2 PE |
350 | long_int lyear_requested = year_requested; |
351 | long_int year = lyear_requested + mon_years; | |
80fd7387 | 352 | |
8592ae92 | 353 | /* The other values need not be in range: |
8e6fd2bd | 354 | the remaining code handles overflows correctly. */ |
80fd7387 RM |
355 | |
356 | /* Calculate day of year from year, month, and day of month. | |
357 | The result need not be in range. */ | |
e507cc56 RM |
358 | int mon_yday = ((__mon_yday[leapyear (year)] |
359 | [mon_remainder + 12 * negative_mon_remainder]) | |
360 | - 1); | |
f04dfbc2 PE |
361 | long_int lmday = mday; |
362 | long_int yday = mon_yday + lmday; | |
e507cc56 | 363 | |
8e6fd2bd PE |
364 | mktime_offset_t off = *offset; |
365 | int negative_offset_guess; | |
80fd7387 | 366 | |
9a0a462c | 367 | int sec_requested = sec; |
55544141 | 368 | |
e507cc56 RM |
369 | if (LEAP_SECONDS_POSSIBLE) |
370 | { | |
371 | /* Handle out-of-range seconds specially, | |
efbdddc3 | 372 | since ydhms_diff assumes every minute has 60 seconds. */ |
e507cc56 RM |
373 | if (sec < 0) |
374 | sec = 0; | |
375 | if (59 < sec) | |
376 | sec = 59; | |
377 | } | |
378 | ||
379 | /* Invert CONVERT by probing. First assume the same offset as last | |
380 | time. */ | |
381 | ||
8e6fd2bd | 382 | INT_SUBTRACT_WRAPV (0, off, &negative_offset_guess); |
86aece3b PE |
383 | long_int t0 = ydhms_diff (year, yday, hour, min, sec, |
384 | EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, | |
385 | negative_offset_guess); | |
386 | long_int t = t0, t1 = t0, t2 = t0; | |
80fd7387 | 387 | |
e507cc56 | 388 | /* Repeatedly use the error to improve the guess. */ |
28f540f4 | 389 | |
86aece3b PE |
390 | while (true) |
391 | { | |
392 | if (! ranged_convert (convert, &t, &tm)) | |
de20b81a | 393 | return -1; |
86aece3b PE |
394 | long_int dt = tm_diff (year, yday, hour, min, sec, &tm); |
395 | if (dt == 0) | |
396 | break; | |
397 | ||
398 | if (t == t1 && t != t2 | |
399 | && (tm.tm_isdst < 0 | |
400 | || (isdst < 0 | |
401 | ? dst2 <= (tm.tm_isdst != 0) | |
402 | : (isdst != 0) != (tm.tm_isdst != 0)))) | |
403 | /* We can't possibly find a match, as we are oscillating | |
404 | between two values. The requested time probably falls | |
405 | within a spring-forward gap of size DT. Follow the common | |
406 | practice in this case, which is to return a time that is DT | |
407 | away from the requested time, preferring a time whose | |
408 | tm_isdst differs from the requested value. (If no tm_isdst | |
409 | was requested and only one of the two values has a nonzero | |
410 | tm_isdst, prefer that value.) In practice, this is more | |
411 | useful than returning -1. */ | |
412 | goto offset_found; | |
413 | ||
414 | remaining_probes--; | |
415 | if (remaining_probes == 0) | |
416 | { | |
417 | __set_errno (EOVERFLOW); | |
418 | return -1; | |
419 | } | |
420 | ||
421 | t1 = t2, t2 = t, t += dt, dst2 = tm.tm_isdst != 0; | |
422 | } | |
80fd7387 | 423 | |
e507cc56 | 424 | /* We have a match. Check whether tm.tm_isdst has the requested |
25b3b17b | 425 | value, if any. */ |
ce73d683 | 426 | if (isdst_differ (isdst, tm.tm_isdst)) |
80fd7387 | 427 | { |
c0016081 UD |
428 | /* tm.tm_isdst has the wrong value. Look for a neighboring |
429 | time with the right value, and use its UTC offset. | |
c0016081 | 430 | |
e507cc56 | 431 | Heuristic: probe the adjacent timestamps in both directions, |
83859e11 PE |
432 | looking for the desired isdst. If none is found within a |
433 | reasonable duration bound, assume a one-hour DST difference. | |
434 | This should work for all real time zone histories in the tz | |
435 | database. */ | |
436 | ||
437 | /* +1 if we wanted standard time but got DST, -1 if the reverse. */ | |
438 | int dst_difference = (isdst == 0) - (tm.tm_isdst == 0); | |
e507cc56 RM |
439 | |
440 | /* Distance between probes when looking for a DST boundary. In | |
441 | tzdata2003a, the shortest period of DST is 601200 seconds | |
442 | (e.g., America/Recife starting 2000-10-08 01:00), and the | |
443 | shortest period of non-DST surrounded by DST is 694800 | |
444 | seconds (Africa/Tunis starting 1943-04-17 01:00). Use the | |
445 | minimum of these two values, so we don't miss these short | |
446 | periods when probing. */ | |
447 | int stride = 601200; | |
448 | ||
83859e11 PE |
449 | /* In TZDB 2021e, the longest period of DST (or of non-DST), in |
450 | which the DST (or adjacent DST) difference is not one hour, | |
451 | is 457243209 seconds: e.g., America/Cambridge_Bay with leap | |
452 | seconds, starting 1965-10-31 00:00 in a switch from | |
453 | double-daylight time (-05) to standard time (-07), and | |
454 | continuing to 1980-04-27 02:00 in a switch from standard time | |
455 | (-07) to daylight time (-06). */ | |
456 | int duration_max = 457243209; | |
e507cc56 RM |
457 | |
458 | /* Search in both directions, so the maximum distance is half | |
459 | the duration; add the stride to avoid off-by-1 problems. */ | |
460 | int delta_bound = duration_max / 2 + stride; | |
461 | ||
462 | int delta, direction; | |
463 | ||
464 | for (delta = stride; delta < delta_bound; delta += stride) | |
465 | for (direction = -1; direction <= 1; direction += 2) | |
8e6fd2bd PE |
466 | { |
467 | long_int ot; | |
468 | if (! INT_ADD_WRAPV (t, delta * direction, &ot)) | |
469 | { | |
470 | struct tm otm; | |
86aece3b PE |
471 | if (! ranged_convert (convert, &ot, &otm)) |
472 | return -1; | |
8e6fd2bd PE |
473 | if (! isdst_differ (isdst, otm.tm_isdst)) |
474 | { | |
475 | /* We found the desired tm_isdst. | |
476 | Extrapolate back to the desired time. */ | |
86aece3b PE |
477 | long_int gt = ot + tm_diff (year, yday, hour, min, sec, |
478 | &otm); | |
479 | if (mktime_min <= gt && gt <= mktime_max) | |
480 | { | |
481 | if (convert_time (convert, gt, &tm)) | |
482 | { | |
483 | t = gt; | |
484 | goto offset_found; | |
485 | } | |
486 | if (errno != EOVERFLOW) | |
487 | return -1; | |
488 | } | |
8e6fd2bd PE |
489 | } |
490 | } | |
491 | } | |
86aece3b | 492 | |
83859e11 PE |
493 | /* No unusual DST offset was found nearby. Assume one-hour DST. */ |
494 | t += 60 * 60 * dst_difference; | |
495 | if (mktime_min <= t && t <= mktime_max && convert_time (convert, t, &tm)) | |
496 | goto offset_found; | |
497 | ||
86aece3b PE |
498 | __set_errno (EOVERFLOW); |
499 | return -1; | |
80fd7387 | 500 | } |
28f540f4 | 501 | |
e507cc56 | 502 | offset_found: |
8e6fd2bd PE |
503 | /* Set *OFFSET to the low-order bits of T - T0 - NEGATIVE_OFFSET_GUESS. |
504 | This is just a heuristic to speed up the next mktime call, and | |
505 | correctness is unaffected if integer overflow occurs here. */ | |
6c90d759 PE |
506 | INT_SUBTRACT_WRAPV (t, t0, offset); |
507 | INT_SUBTRACT_WRAPV (*offset, negative_offset_guess, offset); | |
80fd7387 | 508 | |
e507cc56 | 509 | if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec) |
80fd7387 RM |
510 | { |
511 | /* Adjust time to reflect the tm_sec requested, not the normalized value. | |
512 | Also, repair any damage from a false match due to a leap second. */ | |
8e6fd2bd PE |
513 | long_int sec_adjustment = sec == 0 && tm.tm_sec == 60; |
514 | sec_adjustment -= sec; | |
515 | sec_adjustment += sec_requested; | |
516 | if (INT_ADD_WRAPV (t, sec_adjustment, &t) | |
de20b81a PE |
517 | || ! (mktime_min <= t && t <= mktime_max)) |
518 | { | |
519 | __set_errno (EOVERFLOW); | |
520 | return -1; | |
521 | } | |
522 | if (! convert_time (convert, t, &tm)) | |
78575a84 UD |
523 | return -1; |
524 | } | |
525 | ||
80fd7387 RM |
526 | *tp = tm; |
527 | return t; | |
528 | } | |
529 | ||
8e6fd2bd | 530 | #endif /* _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_INTERNAL */ |
eda78eec | 531 | |
8e6fd2bd | 532 | #if defined _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS |
eda78eec | 533 | |
20aa5819 PE |
534 | /* Convert *TP to a __time64_t value. */ |
535 | __time64_t | |
536 | __mktime64 (struct tm *tp) | |
eda78eec | 537 | { |
eda78eec | 538 | /* POSIX.1 8.1.1 requires that whenever mktime() is called, the |
6226efbd | 539 | time zone names contained in the external variable 'tzname' shall |
eda78eec UD |
540 | be set as if the tzset() function had been called. */ |
541 | __tzset (); | |
eda78eec | 542 | |
8e6fd2bd PE |
543 | # if defined _LIBC || NEED_MKTIME_WORKING |
544 | static mktime_offset_t localtime_offset; | |
20aa5819 | 545 | return __mktime_internal (tp, __localtime64_r, &localtime_offset); |
8e6fd2bd PE |
546 | # else |
547 | # undef mktime | |
548 | return mktime (tp); | |
549 | # endif | |
eda78eec | 550 | } |
8e6fd2bd | 551 | #endif /* _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS */ |
eda78eec | 552 | |
20aa5819 PE |
553 | #if defined _LIBC && __TIMESIZE != 64 |
554 | ||
555 | libc_hidden_def (__mktime64) | |
556 | ||
557 | time_t | |
558 | mktime (struct tm *tp) | |
559 | { | |
560 | struct tm tm = *tp; | |
561 | __time64_t t = __mktime64 (&tm); | |
562 | if (in_time_t_range (t)) | |
563 | { | |
564 | *tp = tm; | |
565 | return t; | |
566 | } | |
567 | else | |
568 | { | |
569 | __set_errno (EOVERFLOW); | |
570 | return -1; | |
571 | } | |
572 | } | |
573 | ||
28f540f4 | 574 | #endif |
c5598d47 | 575 | |
20aa5819 | 576 | weak_alias (mktime, timelocal) |
c5598d47 RM |
577 | libc_hidden_def (mktime) |
578 | libc_hidden_weak (timelocal) |