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98f1928d PE |
1 | /* Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc. |
2 | Contributed by Paul Eggert (eggert@twinsun.com). | |
3 | ||
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4 | NOTE: The canonical source of this file is maintained with the GNU C Library. |
5 | Bugs can be reported to bug-glibc@prep.ai.mit.edu. | |
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7 | This program is free software; you can redistribute it and/or modify it |
8 | under the terms of the GNU General Public License as published by the | |
9 | Free Software Foundation; either version 2, or (at your option) any | |
10 | later version. | |
98f1928d | 11 | |
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12 | This program is distributed in the hope that it will be useful, |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
98f1928d | 16 | |
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17 | You should have received a copy of the GNU General Public License |
18 | along with this program; if not, write to the Free Software | |
19 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, | |
20 | USA. */ | |
98f1928d PE |
21 | |
22 | /* Define this to have a standalone program to test this implementation of | |
23 | mktime. */ | |
24 | /* #define DEBUG 1 */ | |
25 | ||
26 | #ifdef HAVE_CONFIG_H | |
6385ec2b | 27 | # include <config.h> |
98f1928d PE |
28 | #endif |
29 | ||
30 | #ifdef _LIBC | |
31 | # define HAVE_LIMITS_H 1 | |
32 | # define HAVE_LOCALTIME_R 1 | |
33 | # define STDC_HEADERS 1 | |
34 | #endif | |
35 | ||
36 | /* Assume that leap seconds are possible, unless told otherwise. | |
37 | If the host has a `zic' command with a `-L leapsecondfilename' option, | |
38 | then it supports leap seconds; otherwise it probably doesn't. */ | |
39 | #ifndef LEAP_SECONDS_POSSIBLE | |
6385ec2b | 40 | # define LEAP_SECONDS_POSSIBLE 1 |
98f1928d PE |
41 | #endif |
42 | ||
43 | #include <sys/types.h> /* Some systems define `time_t' here. */ | |
44 | #include <time.h> | |
45 | ||
46 | #if HAVE_LIMITS_H | |
6385ec2b | 47 | # include <limits.h> |
98f1928d PE |
48 | #endif |
49 | ||
50 | #if DEBUG | |
6385ec2b PE |
51 | # include <stdio.h> |
52 | # if STDC_HEADERS | |
53 | # include <stdlib.h> | |
54 | # endif | |
98f1928d | 55 | /* Make it work even if the system's libc has its own mktime routine. */ |
6385ec2b | 56 | # define mktime my_mktime |
98f1928d PE |
57 | #endif /* DEBUG */ |
58 | ||
59 | #ifndef __P | |
6385ec2b PE |
60 | # if defined (__GNUC__) || (defined (__STDC__) && __STDC__) |
61 | # define __P(args) args | |
62 | # else | |
63 | # define __P(args) () | |
64 | # endif /* GCC. */ | |
98f1928d PE |
65 | #endif /* Not __P. */ |
66 | ||
67 | #ifndef CHAR_BIT | |
6385ec2b | 68 | # define CHAR_BIT 8 |
98f1928d PE |
69 | #endif |
70 | ||
71 | #ifndef INT_MIN | |
6385ec2b | 72 | # define INT_MIN (~0 << (sizeof (int) * CHAR_BIT - 1)) |
98f1928d PE |
73 | #endif |
74 | #ifndef INT_MAX | |
6385ec2b | 75 | # define INT_MAX (~0 - INT_MIN) |
98f1928d PE |
76 | #endif |
77 | ||
78 | #ifndef TIME_T_MIN | |
6385ec2b PE |
79 | /* The outer cast to time_t works around a bug in Cray C 5.0.3.0. */ |
80 | # define TIME_T_MIN ((time_t) \ | |
81 | (0 < (time_t) -1 ? (time_t) 0 \ | |
82 | : ~ (time_t) 0 << (sizeof (time_t) * CHAR_BIT - 1))) | |
98f1928d PE |
83 | #endif |
84 | #ifndef TIME_T_MAX | |
6385ec2b | 85 | # define TIME_T_MAX (~ (time_t) 0 - TIME_T_MIN) |
98f1928d PE |
86 | #endif |
87 | ||
88 | #define TM_YEAR_BASE 1900 | |
89 | #define EPOCH_YEAR 1970 | |
90 | ||
91 | #ifndef __isleap | |
92 | /* Nonzero if YEAR is a leap year (every 4 years, | |
93 | except every 100th isn't, and every 400th is). */ | |
6385ec2b | 94 | # define __isleap(year) \ |
98f1928d PE |
95 | ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0)) |
96 | #endif | |
97 | ||
98 | /* How many days come before each month (0-12). */ | |
99 | const unsigned short int __mon_yday[2][13] = | |
100 | { | |
101 | /* Normal years. */ | |
102 | { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, | |
103 | /* Leap years. */ | |
104 | { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } | |
105 | }; | |
106 | ||
107 | static time_t ydhms_tm_diff __P ((int, int, int, int, int, const struct tm *)); | |
108 | time_t __mktime_internal __P ((struct tm *, | |
109 | struct tm *(*) (const time_t *, struct tm *), | |
110 | time_t *)); | |
111 | ||
112 | ||
113 | #ifdef _LIBC | |
6385ec2b | 114 | # define localtime_r __localtime_r |
98f1928d | 115 | #else |
6385ec2b | 116 | # if ! HAVE_LOCALTIME_R && ! defined localtime_r |
98f1928d | 117 | /* Approximate localtime_r as best we can in its absence. */ |
6385ec2b | 118 | # define localtime_r my_mktime_localtime_r |
98f1928d PE |
119 | static struct tm *localtime_r __P ((const time_t *, struct tm *)); |
120 | static struct tm * | |
121 | localtime_r (t, tp) | |
122 | const time_t *t; | |
123 | struct tm *tp; | |
124 | { | |
125 | struct tm *l = localtime (t); | |
126 | if (! l) | |
127 | return 0; | |
128 | *tp = *l; | |
129 | return tp; | |
130 | } | |
6385ec2b | 131 | # endif /* ! HAVE_LOCALTIME_R && ! defined (localtime_r) */ |
98f1928d PE |
132 | #endif /* ! _LIBC */ |
133 | ||
134 | ||
135 | /* Yield the difference between (YEAR-YDAY HOUR:MIN:SEC) and (*TP), | |
136 | measured in seconds, ignoring leap seconds. | |
137 | YEAR uses the same numbering as TM->tm_year. | |
138 | All values are in range, except possibly YEAR. | |
139 | If overflow occurs, yield the low order bits of the correct answer. */ | |
140 | static time_t | |
141 | ydhms_tm_diff (year, yday, hour, min, sec, tp) | |
142 | int year, yday, hour, min, sec; | |
143 | const struct tm *tp; | |
144 | { | |
145 | /* Compute intervening leap days correctly even if year is negative. | |
146 | Take care to avoid int overflow. time_t overflow is OK, since | |
147 | only the low order bits of the correct time_t answer are needed. | |
148 | Don't convert to time_t until after all divisions are done, since | |
149 | time_t might be unsigned. */ | |
150 | int a4 = (year >> 2) + (TM_YEAR_BASE >> 2) - ! (year & 3); | |
151 | int b4 = (tp->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (tp->tm_year & 3); | |
152 | int a100 = a4 / 25 - (a4 % 25 < 0); | |
153 | int b100 = b4 / 25 - (b4 % 25 < 0); | |
154 | int a400 = a100 >> 2; | |
155 | int b400 = b100 >> 2; | |
156 | int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400); | |
157 | time_t years = year - (time_t) tp->tm_year; | |
158 | time_t days = (365 * years + intervening_leap_days | |
159 | + (yday - tp->tm_yday)); | |
160 | return (60 * (60 * (24 * days + (hour - tp->tm_hour)) | |
161 | + (min - tp->tm_min)) | |
162 | + (sec - tp->tm_sec)); | |
163 | } | |
164 | ||
165 | ||
166 | static time_t localtime_offset; | |
167 | ||
168 | /* Convert *TP to a time_t value. */ | |
169 | time_t | |
170 | mktime (tp) | |
171 | struct tm *tp; | |
172 | { | |
173 | #ifdef _LIBC | |
174 | /* POSIX.1 8.1.1 requires that whenever mktime() is called, the | |
175 | time zone names contained in the external variable `tzname' shall | |
176 | be set as if the tzset() function had been called. */ | |
177 | __tzset (); | |
178 | #endif | |
179 | ||
180 | return __mktime_internal (tp, localtime_r, &localtime_offset); | |
181 | } | |
182 | ||
183 | /* Convert *TP to a time_t value, inverting | |
184 | the monotonic and mostly-unit-linear conversion function CONVERT. | |
185 | Use *OFFSET to keep track of a guess at the offset of the result, | |
186 | compared to what the result would be for UTC without leap seconds. | |
187 | If *OFFSET's guess is correct, only one CONVERT call is needed. */ | |
188 | time_t | |
189 | __mktime_internal (tp, convert, offset) | |
190 | struct tm *tp; | |
191 | struct tm *(*convert) __P ((const time_t *, struct tm *)); | |
192 | time_t *offset; | |
193 | { | |
194 | time_t t, dt, t0; | |
195 | struct tm tm; | |
196 | ||
197 | /* The maximum number of probes (calls to CONVERT) should be enough | |
198 | to handle any combinations of time zone rule changes, solar time, | |
199 | and leap seconds. Posix.1 prohibits leap seconds, but some hosts | |
200 | have them anyway. */ | |
201 | int remaining_probes = 4; | |
202 | ||
203 | /* Time requested. Copy it in case CONVERT modifies *TP; this can | |
204 | occur if TP is localtime's returned value and CONVERT is localtime. */ | |
205 | int sec = tp->tm_sec; | |
206 | int min = tp->tm_min; | |
207 | int hour = tp->tm_hour; | |
208 | int mday = tp->tm_mday; | |
209 | int mon = tp->tm_mon; | |
210 | int year_requested = tp->tm_year; | |
211 | int isdst = tp->tm_isdst; | |
212 | ||
213 | /* Ensure that mon is in range, and set year accordingly. */ | |
214 | int mon_remainder = mon % 12; | |
215 | int negative_mon_remainder = mon_remainder < 0; | |
216 | int mon_years = mon / 12 - negative_mon_remainder; | |
217 | int year = year_requested + mon_years; | |
218 | ||
219 | /* The other values need not be in range: | |
220 | the remaining code handles minor overflows correctly, | |
221 | assuming int and time_t arithmetic wraps around. | |
222 | Major overflows are caught at the end. */ | |
223 | ||
224 | /* Calculate day of year from year, month, and day of month. | |
225 | The result need not be in range. */ | |
226 | int yday = ((__mon_yday[__isleap (year + TM_YEAR_BASE)] | |
227 | [mon_remainder + 12 * negative_mon_remainder]) | |
228 | + mday - 1); | |
229 | ||
230 | #if LEAP_SECONDS_POSSIBLE | |
231 | /* Handle out-of-range seconds specially, | |
232 | since ydhms_tm_diff assumes every minute has 60 seconds. */ | |
233 | int sec_requested = sec; | |
234 | if (sec < 0) | |
235 | sec = 0; | |
236 | if (59 < sec) | |
237 | sec = 59; | |
238 | #endif | |
239 | ||
240 | /* Invert CONVERT by probing. First assume the same offset as last time. | |
241 | Then repeatedly use the error to improve the guess. */ | |
242 | ||
243 | tm.tm_year = EPOCH_YEAR - TM_YEAR_BASE; | |
244 | tm.tm_yday = tm.tm_hour = tm.tm_min = tm.tm_sec = 0; | |
245 | t0 = ydhms_tm_diff (year, yday, hour, min, sec, &tm); | |
246 | ||
247 | for (t = t0 + *offset; | |
248 | (dt = ydhms_tm_diff (year, yday, hour, min, sec, (*convert) (&t, &tm))); | |
249 | t += dt) | |
250 | if (--remaining_probes == 0) | |
251 | return -1; | |
252 | ||
253 | /* Check whether tm.tm_isdst has the requested value, if any. */ | |
254 | if (0 <= isdst && 0 <= tm.tm_isdst) | |
255 | { | |
256 | int dst_diff = (isdst != 0) - (tm.tm_isdst != 0); | |
257 | if (dst_diff) | |
258 | { | |
259 | /* Move two hours in the direction indicated by the disagreement, | |
260 | probe some more, and switch to a new time if found. | |
261 | The largest known fallback due to daylight savings is two hours: | |
262 | once, in Newfoundland, 1988-10-30 02:00 -> 00:00. */ | |
263 | time_t ot = t - 2 * 60 * 60 * dst_diff; | |
264 | while (--remaining_probes != 0) | |
265 | { | |
266 | struct tm otm; | |
267 | if (! (dt = ydhms_tm_diff (year, yday, hour, min, sec, | |
268 | (*convert) (&ot, &otm)))) | |
269 | { | |
270 | t = ot; | |
271 | tm = otm; | |
272 | break; | |
273 | } | |
274 | if ((ot += dt) == t) | |
275 | break; /* Avoid a redundant probe. */ | |
276 | } | |
277 | } | |
278 | } | |
279 | ||
280 | *offset = t - t0; | |
281 | ||
282 | #if LEAP_SECONDS_POSSIBLE | |
283 | if (sec_requested != tm.tm_sec) | |
284 | { | |
285 | /* Adjust time to reflect the tm_sec requested, not the normalized value. | |
286 | Also, repair any damage from a false match due to a leap second. */ | |
287 | t += sec_requested - sec + (sec == 0 && tm.tm_sec == 60); | |
288 | (*convert) (&t, &tm); | |
289 | } | |
290 | #endif | |
291 | ||
292 | if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3) | |
293 | { | |
294 | /* time_t isn't large enough to rule out overflows in ydhms_tm_diff, | |
295 | so check for major overflows. A gross check suffices, | |
296 | since if t has overflowed, it is off by a multiple of | |
297 | TIME_T_MAX - TIME_T_MIN + 1. So ignore any component of | |
298 | the difference that is bounded by a small value. */ | |
299 | ||
300 | double dyear = (double) year_requested + mon_years - tm.tm_year; | |
301 | double dday = 366 * dyear + mday; | |
302 | double dsec = 60 * (60 * (24 * dday + hour) + min) + sec_requested; | |
303 | ||
304 | if (TIME_T_MAX / 3 - TIME_T_MIN / 3 < (dsec < 0 ? - dsec : dsec)) | |
305 | return -1; | |
306 | } | |
307 | ||
308 | *tp = tm; | |
309 | return t; | |
310 | } | |
311 | ||
312 | #ifdef weak_alias | |
313 | weak_alias (mktime, timelocal) | |
314 | #endif | |
315 | \f | |
316 | #if DEBUG | |
317 | ||
318 | static int | |
319 | not_equal_tm (a, b) | |
320 | struct tm *a; | |
321 | struct tm *b; | |
322 | { | |
323 | return ((a->tm_sec ^ b->tm_sec) | |
324 | | (a->tm_min ^ b->tm_min) | |
325 | | (a->tm_hour ^ b->tm_hour) | |
326 | | (a->tm_mday ^ b->tm_mday) | |
327 | | (a->tm_mon ^ b->tm_mon) | |
328 | | (a->tm_year ^ b->tm_year) | |
329 | | (a->tm_mday ^ b->tm_mday) | |
330 | | (a->tm_yday ^ b->tm_yday) | |
331 | | (a->tm_isdst ^ b->tm_isdst)); | |
332 | } | |
333 | ||
334 | static void | |
335 | print_tm (tp) | |
336 | struct tm *tp; | |
337 | { | |
338 | printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d", | |
339 | tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday, | |
340 | tp->tm_hour, tp->tm_min, tp->tm_sec, | |
341 | tp->tm_yday, tp->tm_wday, tp->tm_isdst); | |
342 | } | |
343 | ||
344 | static int | |
345 | check_result (tk, tmk, tl, tml) | |
346 | time_t tk; | |
347 | struct tm tmk; | |
348 | time_t tl; | |
349 | struct tm tml; | |
350 | { | |
351 | if (tk != tl || not_equal_tm (&tmk, &tml)) | |
352 | { | |
353 | printf ("mktime ("); | |
354 | print_tm (&tmk); | |
355 | printf (")\nyields ("); | |
356 | print_tm (&tml); | |
357 | printf (") == %ld, should be %ld\n", (long) tl, (long) tk); | |
358 | return 1; | |
359 | } | |
360 | ||
361 | return 0; | |
362 | } | |
363 | ||
364 | int | |
365 | main (argc, argv) | |
366 | int argc; | |
367 | char **argv; | |
368 | { | |
369 | int status = 0; | |
370 | struct tm tm, tmk, tml; | |
371 | time_t tk, tl; | |
372 | char trailer; | |
373 | ||
374 | if ((argc == 3 || argc == 4) | |
375 | && (sscanf (argv[1], "%d-%d-%d%c", | |
376 | &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer) | |
377 | == 3) | |
378 | && (sscanf (argv[2], "%d:%d:%d%c", | |
379 | &tm.tm_hour, &tm.tm_min, &tm.tm_sec, &trailer) | |
380 | == 3)) | |
381 | { | |
382 | tm.tm_year -= TM_YEAR_BASE; | |
383 | tm.tm_mon--; | |
384 | tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]); | |
385 | tmk = tm; | |
386 | tl = mktime (&tmk); | |
387 | tml = *localtime (&tl); | |
388 | printf ("mktime returns %ld == ", (long) tl); | |
389 | print_tm (&tmk); | |
390 | printf ("\n"); | |
391 | status = check_result (tl, tmk, tl, tml); | |
392 | } | |
393 | else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0)) | |
394 | { | |
395 | time_t from = atol (argv[1]); | |
396 | time_t by = atol (argv[2]); | |
397 | time_t to = atol (argv[3]); | |
398 | ||
399 | if (argc == 4) | |
400 | for (tl = from; tl <= to; tl += by) | |
401 | { | |
402 | tml = *localtime (&tl); | |
403 | tmk = tml; | |
404 | tk = mktime (&tmk); | |
405 | status |= check_result (tk, tmk, tl, tml); | |
406 | } | |
407 | else | |
408 | for (tl = from; tl <= to; tl += by) | |
409 | { | |
410 | /* Null benchmark. */ | |
411 | tml = *localtime (&tl); | |
412 | tmk = tml; | |
413 | tk = tl; | |
414 | status |= check_result (tk, tmk, tl, tml); | |
415 | } | |
416 | } | |
417 | else | |
418 | printf ("Usage:\ | |
419 | \t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\ | |
420 | \t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\ | |
421 | \t%s FROM BY TO - # Do not test those values (for benchmark).\n", | |
422 | argv[0], argv[0], argv[0]); | |
423 | ||
424 | return status; | |
425 | } | |
426 | ||
427 | #endif /* DEBUG */ | |
428 | \f | |
429 | /* | |
430 | Local Variables: | |
431 | compile-command: "gcc -DDEBUG=1 -Wall -O -g mktime.c -o mktime" | |
432 | End: | |
433 | */ |