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6226efbd | 1 | /* Convert a 'struct tm' to a time_t value. |
688903eb | 2 | Copyright (C) 1993-2018 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 | 20 | /* Define this to 1 to have a standalone program to test this implementation of |
28f540f4 | 21 | mktime. */ |
8e6fd2bd PE |
22 | #ifndef DEBUG_MKTIME |
23 | # define DEBUG_MKTIME 0 | |
24 | #endif | |
28f540f4 | 25 | |
8e6fd2bd PE |
26 | /* The following macros influence what gets defined when this file is compiled: |
27 | ||
28 | Macro/expression Which gnulib module This compilation unit | |
29 | should define | |
30 | ||
31 | _LIBC (glibc proper) mktime | |
32 | ||
33 | NEED_MKTIME_WORKING mktime rpl_mktime | |
34 | || NEED_MKTIME_WINDOWS | |
35 | ||
36 | NEED_MKTIME_INTERNAL mktime-internal mktime_internal | |
37 | ||
38 | DEBUG_MKTIME (defined manually) my_mktime, main | |
39 | */ | |
40 | ||
41 | #if !defined _LIBC && !DEBUG_MKTIME | |
de20b81a | 42 | # include <libc-config.h> |
28f540f4 RM |
43 | #endif |
44 | ||
80fd7387 | 45 | /* Assume that leap seconds are possible, unless told otherwise. |
6226efbd | 46 | If the host has a 'zic' command with a '-L leapsecondfilename' option, |
80fd7387 RM |
47 | then it supports leap seconds; otherwise it probably doesn't. */ |
48 | #ifndef LEAP_SECONDS_POSSIBLE | |
9c2322bc | 49 | # define LEAP_SECONDS_POSSIBLE 1 |
80fd7387 RM |
50 | #endif |
51 | ||
28f540f4 RM |
52 | #include <time.h> |
53 | ||
de20b81a | 54 | #include <errno.h> |
85e07670 | 55 | #include <limits.h> |
8e6fd2bd PE |
56 | #include <stdbool.h> |
57 | #include <stdlib.h> | |
58 | #include <string.h> | |
28f540f4 | 59 | |
8e6fd2bd PE |
60 | #include <intprops.h> |
61 | #include <verify.h> | |
9b5204dd | 62 | |
8e6fd2bd | 63 | #if DEBUG_MKTIME |
9c2322bc | 64 | # include <stdio.h> |
80fd7387 | 65 | /* Make it work even if the system's libc has its own mktime routine. */ |
826dd0ab | 66 | # undef mktime |
9c2322bc | 67 | # define mktime my_mktime |
f2b3078e | 68 | #endif /* DEBUG_MKTIME */ |
28f540f4 | 69 | |
8e6fd2bd PE |
70 | #ifndef NEED_MKTIME_INTERNAL |
71 | # define NEED_MKTIME_INTERNAL 0 | |
72 | #endif | |
73 | #ifndef NEED_MKTIME_WINDOWS | |
74 | # define NEED_MKTIME_WINDOWS 0 | |
75 | #endif | |
76 | #ifndef NEED_MKTIME_WORKING | |
77 | # define NEED_MKTIME_WORKING DEBUG_MKTIME | |
78 | #endif | |
79 | ||
80 | #include "mktime-internal.h" | |
81 | ||
5a580643 | 82 | #if !defined _LIBC && (NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS) |
8e6fd2bd PE |
83 | static void |
84 | my_tzset (void) | |
85 | { | |
86 | # if NEED_MKTIME_WINDOWS | |
87 | /* Rectify the value of the environment variable TZ. | |
88 | There are four possible kinds of such values: | |
89 | - Traditional US time zone names, e.g. "PST8PDT". Syntax: see | |
90 | <https://msdn.microsoft.com/en-us/library/90s5c885.aspx> | |
91 | - Time zone names based on geography, that contain one or more | |
92 | slashes, e.g. "Europe/Moscow". | |
93 | - Time zone names based on geography, without slashes, e.g. | |
94 | "Singapore". | |
95 | - Time zone names that contain explicit DST rules. Syntax: see | |
96 | <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03> | |
97 | The Microsoft CRT understands only the first kind. It produces incorrect | |
98 | results if the value of TZ is of the other kinds. | |
99 | But in a Cygwin environment, /etc/profile.d/tzset.sh sets TZ to a value | |
100 | of the second kind for most geographies, or of the first kind in a few | |
101 | other geographies. If it is of the second kind, neutralize it. For the | |
102 | Microsoft CRT, an absent or empty TZ means the time zone that the user | |
103 | has set in the Windows Control Panel. | |
104 | If the value of TZ is of the third or fourth kind -- Cygwin programs | |
105 | understand these syntaxes as well --, it does not matter whether we | |
106 | neutralize it or not, since these values occur only when a Cygwin user | |
107 | has set TZ explicitly; this case is 1. rare and 2. under the user's | |
108 | responsibility. */ | |
109 | const char *tz = getenv ("TZ"); | |
110 | if (tz != NULL && strchr (tz, '/') != NULL) | |
111 | _putenv ("TZ="); | |
112 | # elif HAVE_TZSET | |
113 | tzset (); | |
62bdf9a6 | 114 | # endif |
8e6fd2bd PE |
115 | } |
116 | # undef __tzset | |
117 | # define __tzset() my_tzset () | |
62bdf9a6 PE |
118 | #endif |
119 | ||
8e6fd2bd PE |
120 | #if defined _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_INTERNAL |
121 | ||
122 | /* A signed type that can represent an integer number of years | |
123 | multiplied by three times the number of seconds in a year. It is | |
124 | needed when converting a tm_year value times the number of seconds | |
125 | in a year. The factor of three comes because these products need | |
126 | to be subtracted from each other, and sometimes with an offset | |
127 | added to them, without worrying about overflow. | |
128 | ||
129 | Much of the code uses long_int to represent time_t values, to | |
130 | lessen the hassle of dealing with platforms where time_t is | |
131 | unsigned, and because long_int should suffice to represent all | |
132 | time_t values that mktime can generate even on platforms where | |
133 | time_t is excessively wide. */ | |
f04dfbc2 | 134 | |
8e6fd2bd | 135 | #if INT_MAX <= LONG_MAX / 3 / 366 / 24 / 60 / 60 |
f04dfbc2 PE |
136 | typedef long int long_int; |
137 | #else | |
138 | typedef long long int long_int; | |
139 | #endif | |
8e6fd2bd | 140 | verify (INT_MAX <= TYPE_MAXIMUM (long_int) / 3 / 366 / 24 / 60 / 60); |
f04dfbc2 | 141 | |
1c67fabd | 142 | /* Shift A right by B bits portably, by dividing A by 2**B and |
8e6fd2bd PE |
143 | truncating towards minus infinity. B should be in the range 0 <= B |
144 | <= LONG_INT_BITS - 2, where LONG_INT_BITS is the number of useful | |
145 | bits in a long_int. LONG_INT_BITS is at least 32. | |
1c67fabd RM |
146 | |
147 | ISO C99 says that A >> B is implementation-defined if A < 0. Some | |
148 | implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift | |
149 | right in the usual way when A < 0, so SHR falls back on division if | |
150 | ordinary A >> B doesn't seem to be the usual signed shift. */ | |
28f540f4 | 151 | |
8e6fd2bd PE |
152 | static long_int |
153 | shr (long_int a, int b) | |
154 | { | |
155 | long_int one = 1; | |
156 | return (-one >> 1 == -1 | |
157 | ? a >> b | |
158 | : a / (one << b) - (a % (one << b) < 0)); | |
159 | } | |
160 | ||
161 | /* Bounds for the intersection of time_t and long_int. */ | |
162 | ||
163 | static long_int const mktime_min | |
164 | = ((TYPE_SIGNED (time_t) && TYPE_MINIMUM (time_t) < TYPE_MINIMUM (long_int)) | |
165 | ? TYPE_MINIMUM (long_int) : TYPE_MINIMUM (time_t)); | |
166 | static long_int const mktime_max | |
167 | = (TYPE_MAXIMUM (long_int) < TYPE_MAXIMUM (time_t) | |
168 | ? TYPE_MAXIMUM (long_int) : TYPE_MAXIMUM (time_t)); | |
169 | ||
170 | verify (TYPE_IS_INTEGER (time_t)); | |
a28a0500 | 171 | |
80fd7387 | 172 | #define EPOCH_YEAR 1970 |
a28a0500 | 173 | #define TM_YEAR_BASE 1900 |
8e6fd2bd | 174 | verify (TM_YEAR_BASE % 100 == 0); |
28f540f4 | 175 | |
8e6fd2bd PE |
176 | /* Is YEAR + TM_YEAR_BASE a leap year? */ |
177 | static bool | |
f04dfbc2 | 178 | leapyear (long_int year) |
72035294 RM |
179 | { |
180 | /* Don't add YEAR to TM_YEAR_BASE, as that might overflow. | |
181 | Also, work even if YEAR is negative. */ | |
182 | return | |
183 | ((year & 3) == 0 | |
184 | && (year % 100 != 0 | |
185 | || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3))); | |
186 | } | |
28f540f4 | 187 | |
80fd7387 | 188 | /* How many days come before each month (0-12). */ |
8592ae92 UD |
189 | #ifndef _LIBC |
190 | static | |
191 | #endif | |
80fd7387 RM |
192 | const unsigned short int __mon_yday[2][13] = |
193 | { | |
194 | /* Normal years. */ | |
195 | { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, | |
196 | /* Leap years. */ | |
197 | { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } | |
198 | }; | |
28f540f4 | 199 | |
28f540f4 | 200 | |
8e6fd2bd PE |
201 | /* Do the values A and B differ according to the rules for tm_isdst? |
202 | A and B differ if one is zero and the other positive. */ | |
203 | static bool | |
ce73d683 PE |
204 | isdst_differ (int a, int b) |
205 | { | |
206 | return (!a != !b) && (0 <= a) && (0 <= b); | |
207 | } | |
208 | ||
e507cc56 RM |
209 | /* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) - |
210 | (YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks | |
8e6fd2bd | 211 | were not adjusted between the timestamps. |
80fd7387 | 212 | |
e507cc56 | 213 | The YEAR values uses the same numbering as TP->tm_year. Values |
8e6fd2bd PE |
214 | need not be in the usual range. However, YEAR1 must not overflow |
215 | when multiplied by three times the number of seconds in a year, and | |
216 | likewise for YDAY1 and three times the number of seconds in a day. */ | |
e507cc56 | 217 | |
8e6fd2bd | 218 | static long_int |
f04dfbc2 | 219 | ydhms_diff (long_int year1, long_int yday1, int hour1, int min1, int sec1, |
e507cc56 RM |
220 | int year0, int yday0, int hour0, int min0, int sec0) |
221 | { | |
8e6fd2bd | 222 | verify (-1 / 2 == 0); |
e507cc56 RM |
223 | |
224 | /* Compute intervening leap days correctly even if year is negative. | |
225 | Take care to avoid integer overflow here. */ | |
8e6fd2bd PE |
226 | int a4 = shr (year1, 2) + shr (TM_YEAR_BASE, 2) - ! (year1 & 3); |
227 | int b4 = shr (year0, 2) + shr (TM_YEAR_BASE, 2) - ! (year0 & 3); | |
e507cc56 RM |
228 | int a100 = a4 / 25 - (a4 % 25 < 0); |
229 | int b100 = b4 / 25 - (b4 % 25 < 0); | |
8e6fd2bd PE |
230 | int a400 = shr (a100, 2); |
231 | int b400 = shr (b100, 2); | |
e507cc56 RM |
232 | int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400); |
233 | ||
8e6fd2bd PE |
234 | /* Compute the desired time without overflowing. */ |
235 | long_int years = year1 - year0; | |
236 | long_int days = 365 * years + yday1 - yday0 + intervening_leap_days; | |
237 | long_int hours = 24 * days + hour1 - hour0; | |
238 | long_int minutes = 60 * hours + min1 - min0; | |
239 | long_int seconds = 60 * minutes + sec1 - sec0; | |
e507cc56 RM |
240 | return seconds; |
241 | } | |
242 | ||
8e6fd2bd PE |
243 | /* Return the average of A and B, even if A + B would overflow. |
244 | Round toward positive infinity. */ | |
245 | static long_int | |
246 | long_int_avg (long_int a, long_int b) | |
62bdf9a6 | 247 | { |
8e6fd2bd | 248 | return shr (a, 1) + shr (b, 1) + ((a | b) & 1); |
62bdf9a6 | 249 | } |
e507cc56 RM |
250 | |
251 | /* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC), | |
8e6fd2bd | 252 | assuming that T corresponds to *TP and that no clock adjustments |
e507cc56 | 253 | occurred between *TP and the desired time. |
8e6fd2bd PE |
254 | Although T and the returned value are of type long_int, |
255 | they represent time_t values and must be in time_t range. | |
256 | If TP is null, return a value not equal to T; this avoids false matches. | |
257 | YEAR and YDAY must not be so large that multiplying them by three times the | |
258 | number of seconds in a year (or day, respectively) would overflow long_int. | |
de20b81a PE |
259 | If TP is non-null and the returned value would be out of range, set |
260 | errno to EOVERFLOW and yield a minimal or maximal in-range value | |
261 | that is not equal to T. */ | |
8e6fd2bd | 262 | static long_int |
f04dfbc2 | 263 | guess_time_tm (long_int year, long_int yday, int hour, int min, int sec, |
8e6fd2bd | 264 | long_int t, const struct tm *tp) |
80fd7387 | 265 | { |
e507cc56 | 266 | if (tp) |
fe0ec73e | 267 | { |
8e6fd2bd PE |
268 | long_int result; |
269 | long_int d = ydhms_diff (year, yday, hour, min, sec, | |
270 | tp->tm_year, tp->tm_yday, | |
271 | tp->tm_hour, tp->tm_min, tp->tm_sec); | |
272 | if (! INT_ADD_WRAPV (t, d, &result)) | |
273 | return result; | |
de20b81a | 274 | __set_errno (EOVERFLOW); |
fe0ec73e | 275 | } |
e507cc56 | 276 | |
de20b81a | 277 | /* An error occurred, probably overflow. Return the nearest result |
e507cc56 RM |
278 | that is actually in range, except don't report a zero difference |
279 | if the actual difference is nonzero, as that would cause a false | |
41aba3d7 UD |
280 | match; and don't oscillate between two values, as that would |
281 | confuse the spring-forward gap detector. */ | |
8e6fd2bd PE |
282 | return (t < long_int_avg (mktime_min, mktime_max) |
283 | ? (t <= mktime_min + 1 ? t + 1 : mktime_min) | |
284 | : (mktime_max - 1 <= t ? t - 1 : mktime_max)); | |
285 | } | |
286 | ||
287 | /* Use CONVERT to convert T to a struct tm value in *TM. T must be in | |
288 | range for time_t. Return TM if successful, NULL if T is out of | |
289 | range for CONVERT. */ | |
290 | static struct tm * | |
291 | convert_time (struct tm *(*convert) (const time_t *, struct tm *), | |
292 | long_int t, struct tm *tm) | |
293 | { | |
294 | time_t x = t; | |
295 | return convert (&x, tm); | |
80fd7387 RM |
296 | } |
297 | ||
fe0ec73e UD |
298 | /* Use CONVERT to convert *T to a broken down time in *TP. |
299 | If *T is out of range for conversion, adjust it so that | |
8e6fd2bd PE |
300 | it is the nearest in-range value and then convert that. |
301 | A value is in range if it fits in both time_t and long_int. */ | |
fe0ec73e | 302 | static struct tm * |
eda78eec | 303 | ranged_convert (struct tm *(*convert) (const time_t *, struct tm *), |
8e6fd2bd | 304 | long_int *t, struct tm *tp) |
fe0ec73e | 305 | { |
8e6fd2bd PE |
306 | struct tm *r; |
307 | if (*t < mktime_min) | |
308 | *t = mktime_min; | |
309 | else if (mktime_max < *t) | |
310 | *t = mktime_max; | |
311 | r = convert_time (convert, *t, tp); | |
fe0ec73e | 312 | |
40437871 | 313 | if (!r && *t) |
fe0ec73e | 314 | { |
8e6fd2bd PE |
315 | long_int bad = *t; |
316 | long_int ok = 0; | |
fe0ec73e | 317 | |
8e6fd2bd | 318 | /* BAD is a known unconvertible value, and OK is a known good one. |
fe0ec73e UD |
319 | Use binary search to narrow the range between BAD and OK until |
320 | they differ by 1. */ | |
8e6fd2bd | 321 | while (true) |
fe0ec73e | 322 | { |
8e6fd2bd PE |
323 | long_int mid = long_int_avg (ok, bad); |
324 | if (mid != ok && mid != bad) | |
325 | break; | |
326 | r = convert_time (convert, mid, tp); | |
40437871 RM |
327 | if (r) |
328 | ok = mid; | |
fe0ec73e UD |
329 | else |
330 | bad = mid; | |
331 | } | |
332 | ||
333 | if (!r && ok) | |
334 | { | |
335 | /* The last conversion attempt failed; | |
336 | revert to the most recent successful attempt. */ | |
8e6fd2bd | 337 | r = convert_time (convert, ok, tp); |
fe0ec73e UD |
338 | } |
339 | } | |
340 | ||
341 | return r; | |
342 | } | |
343 | ||
344 | ||
80fd7387 RM |
345 | /* Convert *TP to a time_t value, inverting |
346 | the monotonic and mostly-unit-linear conversion function CONVERT. | |
347 | Use *OFFSET to keep track of a guess at the offset of the result, | |
348 | compared to what the result would be for UTC without leap seconds. | |
e507cc56 | 349 | If *OFFSET's guess is correct, only one CONVERT call is needed. |
de20b81a PE |
350 | If successful, set *TP to the canonicalized struct tm; |
351 | otherwise leave *TP alone, return ((time_t) -1) and set errno. | |
e507cc56 | 352 | This function is external because it is used also by timegm.c. */ |
80fd7387 | 353 | time_t |
eda78eec UD |
354 | __mktime_internal (struct tm *tp, |
355 | struct tm *(*convert) (const time_t *, struct tm *), | |
8e6fd2bd | 356 | mktime_offset_t *offset) |
28f540f4 | 357 | { |
8e6fd2bd | 358 | long_int t, gt, t0, t1, t2, dt; |
80fd7387 RM |
359 | struct tm tm; |
360 | ||
361 | /* The maximum number of probes (calls to CONVERT) should be enough | |
362 | to handle any combinations of time zone rule changes, solar time, | |
25b3b17b UD |
363 | leap seconds, and oscillations around a spring-forward gap. |
364 | POSIX.1 prohibits leap seconds, but some hosts have them anyway. */ | |
365 | int remaining_probes = 6; | |
80fd7387 RM |
366 | |
367 | /* Time requested. Copy it in case CONVERT modifies *TP; this can | |
368 | occur if TP is localtime's returned value and CONVERT is localtime. */ | |
369 | int sec = tp->tm_sec; | |
370 | int min = tp->tm_min; | |
371 | int hour = tp->tm_hour; | |
372 | int mday = tp->tm_mday; | |
373 | int mon = tp->tm_mon; | |
374 | int year_requested = tp->tm_year; | |
ce73d683 | 375 | int isdst = tp->tm_isdst; |
80fd7387 | 376 | |
b5ef404e UD |
377 | /* 1 if the previous probe was DST. */ |
378 | int dst2; | |
379 | ||
80fd7387 RM |
380 | /* Ensure that mon is in range, and set year accordingly. */ |
381 | int mon_remainder = mon % 12; | |
382 | int negative_mon_remainder = mon_remainder < 0; | |
383 | int mon_years = mon / 12 - negative_mon_remainder; | |
f04dfbc2 PE |
384 | long_int lyear_requested = year_requested; |
385 | long_int year = lyear_requested + mon_years; | |
80fd7387 | 386 | |
8592ae92 | 387 | /* The other values need not be in range: |
8e6fd2bd | 388 | the remaining code handles overflows correctly. */ |
80fd7387 RM |
389 | |
390 | /* Calculate day of year from year, month, and day of month. | |
391 | The result need not be in range. */ | |
e507cc56 RM |
392 | int mon_yday = ((__mon_yday[leapyear (year)] |
393 | [mon_remainder + 12 * negative_mon_remainder]) | |
394 | - 1); | |
f04dfbc2 PE |
395 | long_int lmday = mday; |
396 | long_int yday = mon_yday + lmday; | |
e507cc56 | 397 | |
8e6fd2bd PE |
398 | mktime_offset_t off = *offset; |
399 | int negative_offset_guess; | |
80fd7387 | 400 | |
9a0a462c | 401 | int sec_requested = sec; |
55544141 | 402 | |
e507cc56 RM |
403 | if (LEAP_SECONDS_POSSIBLE) |
404 | { | |
405 | /* Handle out-of-range seconds specially, | |
406 | since ydhms_tm_diff assumes every minute has 60 seconds. */ | |
407 | if (sec < 0) | |
408 | sec = 0; | |
409 | if (59 < sec) | |
410 | sec = 59; | |
411 | } | |
412 | ||
413 | /* Invert CONVERT by probing. First assume the same offset as last | |
414 | time. */ | |
415 | ||
8e6fd2bd | 416 | INT_SUBTRACT_WRAPV (0, off, &negative_offset_guess); |
e507cc56 | 417 | t0 = ydhms_diff (year, yday, hour, min, sec, |
8e6fd2bd | 418 | EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, negative_offset_guess); |
80fd7387 | 419 | |
e507cc56 | 420 | /* Repeatedly use the error to improve the guess. */ |
28f540f4 | 421 | |
e507cc56 | 422 | for (t = t1 = t2 = t0, dst2 = 0; |
8e6fd2bd | 423 | (gt = guess_time_tm (year, yday, hour, min, sec, t, |
e507cc56 RM |
424 | ranged_convert (convert, &t, &tm)), |
425 | t != gt); | |
426 | t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0) | |
25b3b17b | 427 | if (t == t1 && t != t2 |
b5ef404e UD |
428 | && (tm.tm_isdst < 0 |
429 | || (isdst < 0 | |
430 | ? dst2 <= (tm.tm_isdst != 0) | |
431 | : (isdst != 0) != (tm.tm_isdst != 0)))) | |
25b3b17b UD |
432 | /* We can't possibly find a match, as we are oscillating |
433 | between two values. The requested time probably falls | |
e507cc56 RM |
434 | within a spring-forward gap of size GT - T. Follow the common |
435 | practice in this case, which is to return a time that is GT - T | |
25b3b17b | 436 | away from the requested time, preferring a time whose |
b5ef404e UD |
437 | tm_isdst differs from the requested value. (If no tm_isdst |
438 | was requested and only one of the two values has a nonzero | |
439 | tm_isdst, prefer that value.) In practice, this is more | |
440 | useful than returning -1. */ | |
e507cc56 | 441 | goto offset_found; |
25b3b17b | 442 | else if (--remaining_probes == 0) |
de20b81a PE |
443 | { |
444 | __set_errno (EOVERFLOW); | |
445 | return -1; | |
446 | } | |
80fd7387 | 447 | |
e507cc56 | 448 | /* We have a match. Check whether tm.tm_isdst has the requested |
25b3b17b | 449 | value, if any. */ |
ce73d683 | 450 | if (isdst_differ (isdst, tm.tm_isdst)) |
80fd7387 | 451 | { |
c0016081 UD |
452 | /* tm.tm_isdst has the wrong value. Look for a neighboring |
453 | time with the right value, and use its UTC offset. | |
c0016081 | 454 | |
e507cc56 RM |
455 | Heuristic: probe the adjacent timestamps in both directions, |
456 | looking for the desired isdst. This should work for all real | |
457 | time zone histories in the tz database. */ | |
458 | ||
459 | /* Distance between probes when looking for a DST boundary. In | |
460 | tzdata2003a, the shortest period of DST is 601200 seconds | |
461 | (e.g., America/Recife starting 2000-10-08 01:00), and the | |
462 | shortest period of non-DST surrounded by DST is 694800 | |
463 | seconds (Africa/Tunis starting 1943-04-17 01:00). Use the | |
464 | minimum of these two values, so we don't miss these short | |
465 | periods when probing. */ | |
466 | int stride = 601200; | |
467 | ||
468 | /* The longest period of DST in tzdata2003a is 536454000 seconds | |
469 | (e.g., America/Jujuy starting 1946-10-01 01:00). The longest | |
470 | period of non-DST is much longer, but it makes no real sense | |
471 | to search for more than a year of non-DST, so use the DST | |
472 | max. */ | |
473 | int duration_max = 536454000; | |
474 | ||
475 | /* Search in both directions, so the maximum distance is half | |
476 | the duration; add the stride to avoid off-by-1 problems. */ | |
477 | int delta_bound = duration_max / 2 + stride; | |
478 | ||
479 | int delta, direction; | |
480 | ||
481 | for (delta = stride; delta < delta_bound; delta += stride) | |
482 | for (direction = -1; direction <= 1; direction += 2) | |
8e6fd2bd PE |
483 | { |
484 | long_int ot; | |
485 | if (! INT_ADD_WRAPV (t, delta * direction, &ot)) | |
486 | { | |
487 | struct tm otm; | |
488 | ranged_convert (convert, &ot, &otm); | |
489 | if (! isdst_differ (isdst, otm.tm_isdst)) | |
490 | { | |
491 | /* We found the desired tm_isdst. | |
492 | Extrapolate back to the desired time. */ | |
493 | t = guess_time_tm (year, yday, hour, min, sec, ot, &otm); | |
494 | ranged_convert (convert, &t, &tm); | |
495 | goto offset_found; | |
496 | } | |
497 | } | |
498 | } | |
80fd7387 | 499 | } |
28f540f4 | 500 | |
e507cc56 | 501 | offset_found: |
8e6fd2bd PE |
502 | /* Set *OFFSET to the low-order bits of T - T0 - NEGATIVE_OFFSET_GUESS. |
503 | This is just a heuristic to speed up the next mktime call, and | |
504 | correctness is unaffected if integer overflow occurs here. */ | |
505 | INT_SUBTRACT_WRAPV (t, t0, &dt); | |
506 | INT_SUBTRACT_WRAPV (dt, negative_offset_guess, offset); | |
80fd7387 | 507 | |
e507cc56 | 508 | if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec) |
80fd7387 RM |
509 | { |
510 | /* Adjust time to reflect the tm_sec requested, not the normalized value. | |
511 | Also, repair any damage from a false match due to a leap second. */ | |
8e6fd2bd PE |
512 | long_int sec_adjustment = sec == 0 && tm.tm_sec == 60; |
513 | sec_adjustment -= sec; | |
514 | sec_adjustment += sec_requested; | |
515 | if (INT_ADD_WRAPV (t, sec_adjustment, &t) | |
de20b81a PE |
516 | || ! (mktime_min <= t && t <= mktime_max)) |
517 | { | |
518 | __set_errno (EOVERFLOW); | |
519 | return -1; | |
520 | } | |
521 | if (! convert_time (convert, t, &tm)) | |
78575a84 UD |
522 | return -1; |
523 | } | |
524 | ||
80fd7387 RM |
525 | *tp = tm; |
526 | return t; | |
527 | } | |
528 | ||
8e6fd2bd | 529 | #endif /* _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_INTERNAL */ |
eda78eec | 530 | |
8e6fd2bd | 531 | #if defined _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS |
eda78eec UD |
532 | |
533 | /* Convert *TP to a time_t value. */ | |
534 | time_t | |
85e07670 | 535 | mktime (struct tm *tp) |
eda78eec | 536 | { |
eda78eec | 537 | /* POSIX.1 8.1.1 requires that whenever mktime() is called, the |
6226efbd | 538 | time zone names contained in the external variable 'tzname' shall |
eda78eec UD |
539 | be set as if the tzset() function had been called. */ |
540 | __tzset (); | |
eda78eec | 541 | |
8e6fd2bd PE |
542 | # if defined _LIBC || NEED_MKTIME_WORKING |
543 | static mktime_offset_t localtime_offset; | |
7683e140 | 544 | return __mktime_internal (tp, __localtime_r, &localtime_offset); |
8e6fd2bd PE |
545 | # else |
546 | # undef mktime | |
547 | return mktime (tp); | |
548 | # endif | |
eda78eec | 549 | } |
8e6fd2bd | 550 | #endif /* _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS */ |
eda78eec | 551 | |
80fd7387 RM |
552 | #ifdef weak_alias |
553 | weak_alias (mktime, timelocal) | |
28f540f4 | 554 | #endif |
c5598d47 RM |
555 | |
556 | #ifdef _LIBC | |
557 | libc_hidden_def (mktime) | |
558 | libc_hidden_weak (timelocal) | |
559 | #endif | |
80fd7387 | 560 | \f |
8e6fd2bd | 561 | #if DEBUG_MKTIME |
28f540f4 | 562 | |
80fd7387 | 563 | static int |
85e07670 | 564 | not_equal_tm (const struct tm *a, const struct tm *b) |
80fd7387 RM |
565 | { |
566 | return ((a->tm_sec ^ b->tm_sec) | |
567 | | (a->tm_min ^ b->tm_min) | |
568 | | (a->tm_hour ^ b->tm_hour) | |
569 | | (a->tm_mday ^ b->tm_mday) | |
570 | | (a->tm_mon ^ b->tm_mon) | |
571 | | (a->tm_year ^ b->tm_year) | |
80fd7387 | 572 | | (a->tm_yday ^ b->tm_yday) |
ce73d683 | 573 | | isdst_differ (a->tm_isdst, b->tm_isdst)); |
80fd7387 | 574 | } |
28f540f4 | 575 | |
80fd7387 | 576 | static void |
85e07670 | 577 | print_tm (const struct tm *tp) |
80fd7387 | 578 | { |
fe0ec73e UD |
579 | if (tp) |
580 | printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d", | |
581 | tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday, | |
582 | tp->tm_hour, tp->tm_min, tp->tm_sec, | |
583 | tp->tm_yday, tp->tm_wday, tp->tm_isdst); | |
584 | else | |
585 | printf ("0"); | |
80fd7387 | 586 | } |
28f540f4 | 587 | |
80fd7387 | 588 | static int |
85e07670 | 589 | check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt) |
80fd7387 | 590 | { |
fe0ec73e | 591 | if (tk != tl || !lt || not_equal_tm (&tmk, lt)) |
80fd7387 RM |
592 | { |
593 | printf ("mktime ("); | |
fe0ec73e | 594 | print_tm (lt); |
85e07670 RM |
595 | printf (")\nyields ("); |
596 | print_tm (&tmk); | |
597 | printf (") == %ld, should be %ld\n", (long int) tk, (long int) tl); | |
80fd7387 RM |
598 | return 1; |
599 | } | |
600 | ||
601 | return 0; | |
602 | } | |
28f540f4 | 603 | |
80fd7387 | 604 | int |
85e07670 | 605 | main (int argc, char **argv) |
80fd7387 RM |
606 | { |
607 | int status = 0; | |
608 | struct tm tm, tmk, tml; | |
fe0ec73e | 609 | struct tm *lt; |
85e07670 | 610 | time_t tk, tl, tl1; |
80fd7387 RM |
611 | char trailer; |
612 | ||
8e6fd2bd PE |
613 | /* Sanity check, plus call tzset. */ |
614 | tl = 0; | |
615 | if (! localtime (&tl)) | |
616 | { | |
617 | printf ("localtime (0) fails\n"); | |
618 | status = 1; | |
619 | } | |
620 | ||
80fd7387 RM |
621 | if ((argc == 3 || argc == 4) |
622 | && (sscanf (argv[1], "%d-%d-%d%c", | |
623 | &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer) | |
624 | == 3) | |
625 | && (sscanf (argv[2], "%d:%d:%d%c", | |
626 | &tm.tm_hour, &tm.tm_min, &tm.tm_sec, &trailer) | |
627 | == 3)) | |
628 | { | |
629 | tm.tm_year -= TM_YEAR_BASE; | |
630 | tm.tm_mon--; | |
631 | tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]); | |
632 | tmk = tm; | |
633 | tl = mktime (&tmk); | |
8e6fd2bd | 634 | lt = localtime_r (&tl, &tml); |
85e07670 | 635 | printf ("mktime returns %ld == ", (long int) tl); |
80fd7387 RM |
636 | print_tm (&tmk); |
637 | printf ("\n"); | |
fe0ec73e | 638 | status = check_result (tl, tmk, tl, lt); |
80fd7387 RM |
639 | } |
640 | else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0)) | |
641 | { | |
642 | time_t from = atol (argv[1]); | |
643 | time_t by = atol (argv[2]); | |
644 | time_t to = atol (argv[3]); | |
28f540f4 | 645 | |
80fd7387 | 646 | if (argc == 4) |
85e07670 | 647 | for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1) |
80fd7387 | 648 | { |
8e6fd2bd | 649 | lt = localtime_r (&tl, &tml); |
fe0ec73e UD |
650 | if (lt) |
651 | { | |
8e6fd2bd | 652 | tmk = tml; |
fe0ec73e | 653 | tk = mktime (&tmk); |
85e07670 | 654 | status |= check_result (tk, tmk, tl, &tml); |
fe0ec73e UD |
655 | } |
656 | else | |
657 | { | |
8e6fd2bd | 658 | printf ("localtime_r (%ld) yields 0\n", (long int) tl); |
fe0ec73e UD |
659 | status = 1; |
660 | } | |
85e07670 RM |
661 | tl1 = tl + by; |
662 | if ((tl1 < tl) != (by < 0)) | |
663 | break; | |
80fd7387 RM |
664 | } |
665 | else | |
85e07670 | 666 | for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1) |
80fd7387 RM |
667 | { |
668 | /* Null benchmark. */ | |
8e6fd2bd | 669 | lt = localtime_r (&tl, &tml); |
fe0ec73e UD |
670 | if (lt) |
671 | { | |
8e6fd2bd | 672 | tmk = tml; |
fe0ec73e | 673 | tk = tl; |
85e07670 | 674 | status |= check_result (tk, tmk, tl, &tml); |
fe0ec73e UD |
675 | } |
676 | else | |
677 | { | |
8e6fd2bd | 678 | printf ("localtime_r (%ld) yields 0\n", (long int) tl); |
fe0ec73e UD |
679 | status = 1; |
680 | } | |
85e07670 RM |
681 | tl1 = tl + by; |
682 | if ((tl1 < tl) != (by < 0)) | |
683 | break; | |
80fd7387 RM |
684 | } |
685 | } | |
686 | else | |
687 | printf ("Usage:\ | |
688 | \t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\ | |
689 | \t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\ | |
690 | \t%s FROM BY TO - # Do not test those values (for benchmark).\n", | |
691 | argv[0], argv[0], argv[0]); | |
692 | ||
693 | return status; | |
28f540f4 | 694 | } |
28f540f4 | 695 | |
f2b3078e | 696 | #endif /* DEBUG_MKTIME */ |
28f540f4 RM |
697 | \f |
698 | /* | |
699 | Local Variables: | |
f2b3078e | 700 | compile-command: "gcc -DDEBUG_MKTIME -I. -Wall -W -O2 -g mktime.c -o mktime" |
28f540f4 RM |
701 | End: |
702 | */ |