source: vendor/patch/2.5.9/maketime.c@ 3729

Last change on this file since 3729 was 3444, checked in by bird, 18 years ago

patch 2.5.9

File size: 14.3 KB
Line 
1/* Convert struct partime into time_t. */
2
3/* Copyright 1992, 1993, 1994, 1995, 1997 Paul Eggert
4 Distributed under license by the Free Software Foundation, Inc.
5
6 This file is part of RCS.
7
8 RCS is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
11 any later version.
12
13 RCS is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with RCS; see the file COPYING.
20 If not, write to the Free Software Foundation,
21 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
22
23 Report problems and direct all questions to:
24
25 rcs-bugs@cs.purdue.edu
26
27 */
28
29/* For maximum portability, use only localtime and gmtime.
30 Make no assumptions about the time_t epoch or the range of time_t values.
31 Avoid mktime because it's not universal and because there's no easy,
32 portable way for mktime to yield the inverse of gmtime. */
33
34#if has_conf_h
35# include <conf.h>
36#else
37# if HAVE_CONFIG_H
38# include <config.h>
39# else
40# ifndef __STDC__
41# define const
42# endif
43# endif
44 /* MIPS RISCOS4.52 defines time_t in <sys/types.h> not <time.h>. */
45# include <sys/types.h>
46# if HAVE_LIMITS_H
47# include <limits.h>
48# endif
49# ifndef LONG_MIN
50# define LONG_MIN (-1-2147483647L)
51# endif
52# if STDC_HEADERS
53# include <stdlib.h>
54# endif
55# include <time.h>
56# ifdef __STDC__
57# define P(x) x
58# else
59# define P(x) ()
60# endif
61#endif
62
63#include <partime.h>
64#include <maketime.h>
65
66char const maket_id[] =
67 "$Id: maketime.c,v 5.17 1999/08/29 11:12:37 eggert Exp $";
68
69static int isleap P ((int));
70static int month_days P ((struct tm const *));
71static time_t maketime P ((struct partime const *, time_t));
72
73/* Suppose A1 + B1 = SUM1, using 2's complement arithmetic ignoring overflow.
74 Suppose A, B and SUM have the same respective signs as A1, B1, and SUM1.
75 Then this yields nonzero if overflow occurred during the addition.
76 Overflow occurs if A and B have the same sign, but A and SUM differ in sign.
77 Use `^' to test whether signs differ, and `< 0' to isolate the sign. */
78#define overflow_sum_sign(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
79
80/* Quotient and remainder when dividing A by B,
81 truncating towards minus infinity, where B is positive. */
82#define DIV(a, b) ((a) / (b) - ((a) % (b) < 0))
83#define MOD(a, b) ((a) % (b) + (b) * ((a) % (b) < 0))
84
85/* Number of days in 400 consecutive Gregorian years. */
86#define Y400_DAYS (365 * 400L + 100 - 4 + 1)
87
88/* Number of years to add to tm_year to get Gregorian year. */
89#define TM_YEAR_ORIGIN 1900
90
91static int
92isleap (y)
93 int y;
94{
95 return (y & 3) == 0 && (y % 100 != 0 || y % 400 == 0);
96}
97
98/* days in year before start of months 0-12 */
99static int const month_yday[] =
100{
101 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
102};
103
104/* Yield the number of days in TM's month. */
105static int
106month_days (tm)
107 struct tm const *tm;
108{
109 int m = tm->tm_mon;
110 return (month_yday[m + 1] - month_yday[m]
111 + (m == 1 && isleap (tm->tm_year + TM_YEAR_ORIGIN)));
112}
113
114/* Convert UNIXTIME to struct tm form.
115 Use gmtime if available and if !LOCALZONE, localtime otherwise. */
116struct tm *
117time2tm (unixtime, localzone)
118 time_t unixtime;
119 int localzone;
120{
121 struct tm *tm;
122#ifdef TZ_is_unset
123 static char const *TZ;
124 if (!TZ && !(TZ = getenv ("TZ")))
125 TZ_is_unset ("The TZ environment variable is not set; please set it to your timezone");
126#endif
127 if (localzone || !(tm = gmtime (&unixtime)))
128 tm = localtime (&unixtime);
129 return tm;
130}
131
132/* Yield A - B, measured in seconds. */
133time_t
134difftm (a, b)
135 struct tm const *a;
136 struct tm const *b;
137{
138 int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
139 int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
140 int ac = DIV (ay, 100);
141 int bc = DIV (by, 100);
142 int difference_in_day_of_year = a->tm_yday - b->tm_yday;
143 int intervening_leap_days = (((ay >> 2) - (by >> 2))
144 - (ac - bc)
145 + ((ac >> 2) - (bc >> 2)));
146 time_t difference_in_years = ay - by;
147 time_t difference_in_days
148 = (difference_in_years * 365
149 + (intervening_leap_days + difference_in_day_of_year));
150 return (((((difference_in_days * 24
151 + (a->tm_hour - b->tm_hour))
152 * 60)
153 + (a->tm_min - b->tm_min))
154 * 60)
155 + (a->tm_sec - b->tm_sec));
156}
157
158/* Adjust time T by adding SECONDS.
159 The absolute value of SECONDS cannot exceed 59 * INT_MAX,
160 and also cannot exceed one month's worth of seconds;
161 this is enough to handle any POSIX or real-life daylight-saving offset.
162 Adjust only T's year, mon, mday, hour, min and sec members;
163 plus adjust wday if it is defined. */
164void
165adjzone (t, seconds)
166 register struct tm *t;
167 long seconds;
168{
169 int days = 0;
170
171 /* This code can be off by a second if SECONDS is not a multiple of 60,
172 if T is local time, and if a leap second happens during this minute.
173 But this bug has never occurred, and most likely will not ever occur.
174 Liberia, the last country for which SECONDS % 60 was nonzero,
175 switched to UTC in May 1972; the first leap second was in June 1972. */
176 int leap_second = t->tm_sec == 60;
177 long sec = seconds + (t->tm_sec - leap_second);
178 if (sec < 0)
179 {
180 if ((t->tm_min -= (59 - sec) / 60) < 0
181 && (t->tm_hour -= (59 - t->tm_min) / 60) < 0)
182 {
183 days = - ((23 - t->tm_hour) / 24);
184 if ((t->tm_mday += days) <= 0)
185 {
186 if (--t->tm_mon < 0)
187 {
188 --t->tm_year;
189 t->tm_mon = 11;
190 }
191 t->tm_mday += month_days (t);
192 }
193 }
194 }
195 else
196 {
197 if (60 <= (t->tm_min += sec / 60)
198 && (24 <= (t->tm_hour += t->tm_min / 60)))
199 {
200 days = t->tm_hour / 24;
201 if (month_days (t) < (t->tm_mday += days))
202 {
203 if (11 < ++t->tm_mon)
204 {
205 ++t->tm_year;
206 t->tm_mon = 0;
207 }
208 t->tm_mday = 1;
209 }
210 }
211 }
212 if (TM_DEFINED (t->tm_wday))
213 t->tm_wday = MOD (t->tm_wday + days, 7);
214 t->tm_hour = MOD (t->tm_hour, 24);
215 t->tm_min = MOD (t->tm_min, 60);
216 t->tm_sec = (int) MOD (sec, 60) + leap_second;
217}
218
219/* Convert TM to time_t, using localtime if LOCALZONE and gmtime otherwise.
220 Use only TM's year, mon, mday, hour, min, and sec members.
221 Ignore TM's old tm_yday and tm_wday, but fill in their correct values.
222 Yield -1 on failure (e.g. a member out of range).
223 POSIX 1003.1 doesn't allow leap seconds, but some implementations
224 have them anyway, so allow them if localtime/gmtime does. */
225time_t
226tm2time (tm, localzone)
227 struct tm *tm;
228 int localzone;
229{
230 /* Cache the most recent t,tm pairs; 1 for gmtime, 1 for localtime. */
231 static time_t t_cache[2];
232 static struct tm tm_cache[2];
233
234 time_t d, gt;
235 struct tm const *gtm;
236 /* The maximum number of iterations should be enough to handle any
237 combinations of leap seconds, time zone rule changes, and solar time.
238 4 is probably enough; we use a bigger number just to be safe. */
239 int remaining_tries = 8;
240
241 /* Avoid subscript errors. */
242 if (12 <= (unsigned) tm->tm_mon)
243 return -1;
244
245 tm->tm_yday = month_yday[tm->tm_mon] + tm->tm_mday
246 - (tm->tm_mon < 2 || !isleap (tm->tm_year + TM_YEAR_ORIGIN));
247
248 /* Make a first guess. */
249 gt = t_cache[localzone];
250 gtm = gt ? &tm_cache[localzone] : time2tm (gt, localzone);
251
252 /* Repeatedly use the error from the guess to improve the guess. */
253 while ((d = difftm (tm, gtm)) != 0)
254 {
255 if (--remaining_tries == 0)
256 return -1;
257 gt += d;
258 gtm = time2tm (gt, localzone);
259 }
260
261 /* Check that the guess actually matches;
262 overflow can cause difftm to yield 0 even on differing times,
263 or tm may have members out of range (e.g. bad leap seconds). */
264#define TM_DIFFER(a,b) \
265 ( \
266 ((a)->tm_year ^ (b)->tm_year) | \
267 ((a)->tm_mon ^ (b)->tm_mon) | \
268 ((a)->tm_mday ^ (b)->tm_mday) | \
269 ((a)->tm_hour ^ (b)->tm_hour) | \
270 ((a)->tm_min ^ (b)->tm_min) | \
271 ((a)->tm_sec ^ (b)->tm_sec) \
272 )
273 if (TM_DIFFER (tm, gtm))
274 {
275 /* If gt is a leap second, try gt+1; if it is one greater than
276 a leap second, try gt-1; otherwise, it doesn't matter.
277 Leap seconds always fall at month end. */
278 int yd = tm->tm_year - gtm->tm_year;
279 gt += yd + (yd ? 0 : tm->tm_mon - gtm->tm_mon);
280 gtm = time2tm (gt, localzone);
281 if (TM_DIFFER (tm, gtm))
282 return -1;
283 }
284 t_cache[localzone] = gt;
285 tm_cache[localzone] = *gtm;
286
287 tm->tm_wday = gtm->tm_wday;
288 return gt;
289}
290
291/* Check *PT and convert it to time_t.
292 If it is incompletely specified, use DEFAULT_TIME to fill it out.
293 Use localtime if PT->zone is the special value TM_LOCAL_ZONE.
294 Yield -1 on failure.
295 ISO 8601 day-of-year and week numbers are not yet supported. */
296static time_t
297maketime (pt, default_time)
298 struct partime const *pt;
299 time_t default_time;
300{
301 int localzone, wday, year;
302 struct tm tm;
303 struct tm *tm0 = 0;
304 time_t r;
305 int use_ordinal_day;
306
307 tm0 = 0; /* Keep gcc -Wall happy. */
308 localzone = pt->zone == TM_LOCAL_ZONE;
309
310 tm = pt->tm;
311 year = tm.tm_year;
312 wday = tm.tm_wday;
313 use_ordinal_day = (!TM_DEFINED (tm.tm_mday)
314 && TM_DEFINED (wday) && TM_DEFINED (pt->wday_ordinal));
315
316 if (use_ordinal_day || TM_DEFINED (pt->ymodulus) || !TM_DEFINED (year))
317 {
318 /* Get tm corresponding to default time. */
319 tm0 = time2tm (default_time, localzone);
320 if (!localzone)
321 adjzone (tm0, pt->zone);
322 }
323
324 if (use_ordinal_day)
325 tm.tm_mday = (tm0->tm_mday
326 + ((wday - tm0->tm_wday + 7) % 7
327 + 7 * (pt->wday_ordinal - (pt->wday_ordinal != 0))));
328
329 if (TM_DEFINED (pt->ymodulus))
330 {
331 /* Yield a year closest to the default that has the given modulus. */
332 int year0 = tm0->tm_year + TM_YEAR_ORIGIN;
333 int y0 = MOD (year0, pt->ymodulus);
334 int d = 2 * (year - y0);
335 year += (((year0 - y0) / pt->ymodulus
336 + (pt->ymodulus < d ? -1 : d < -pt->ymodulus))
337 * pt->ymodulus);
338 }
339 else if (!TM_DEFINED (year))
340 {
341 /* Set default year, month, day from current time. */
342 year = tm0->tm_year + TM_YEAR_ORIGIN;
343 if (!TM_DEFINED (tm.tm_mon))
344 {
345 tm.tm_mon = tm0->tm_mon;
346 if (!TM_DEFINED (tm.tm_mday))
347 tm.tm_mday = tm0->tm_mday;
348 }
349 }
350
351 /* Set remaining default fields to be their minimum values. */
352 if (!TM_DEFINED (tm.tm_mon))
353 tm.tm_mon = 0;
354 if (!TM_DEFINED (tm.tm_mday))
355 tm.tm_mday = 1;
356 if (!TM_DEFINED (tm.tm_hour))
357 tm.tm_hour = 0;
358 if (!TM_DEFINED (tm.tm_min))
359 tm.tm_min = 0;
360 if (!TM_DEFINED (tm.tm_sec))
361 tm.tm_sec = 0;
362
363 tm.tm_year = year - TM_YEAR_ORIGIN;
364 if ((year < tm.tm_year) != (TM_YEAR_ORIGIN < 0))
365 return -1;
366
367 if (!localzone)
368 {
369 adjzone (&tm, -pt->zone);
370 wday = tm.tm_wday;
371 }
372
373 /* Convert and fill in the rest of the tm. */
374 r = tm2time (&tm, localzone);
375 if (r == -1)
376 return r;
377
378 /* Check weekday. */
379 if (TM_DEFINED (wday) && wday != tm.tm_wday)
380 return -1;
381
382 /* Add relative time, except for seconds.
383 We handle seconds separately, at the end,
384 so that leap seconds are handled properly. */
385 if (pt->tmr.tm_year | pt->tmr.tm_mon | pt->tmr.tm_mday
386 | pt->tmr.tm_hour | pt->tmr.tm_min)
387 {
388 int years = tm.tm_year + pt->tmr.tm_year;
389 int mons = tm.tm_mon + pt->tmr.tm_mon;
390 int mdays = tm.tm_mday + pt->tmr.tm_mday;
391 int hours = tm.tm_hour + pt->tmr.tm_hour;
392 int mins = tm.tm_min + pt->tmr.tm_min;
393
394 int carried_hours = DIV (mins, 60);
395 int hours1 = hours + carried_hours;
396 int carried_days = DIV (hours1, 24);
397 int mdays1 = mdays + carried_days;
398
399 int mon0 = MOD (mons, 12);
400 int carried_years0 = DIV (mons, 12);
401 int year0 = years + carried_years0;
402 int yday0 = (month_yday[mon0]
403 - (mon0 < 2 || !isleap (year0 + TM_YEAR_ORIGIN)));
404
405 int yday1 = yday0 + mdays1;
406 int carried_years1 = DIV (yday1, Y400_DAYS) * 400;
407 int year1 = year0 + carried_years1;
408 int yday2 = MOD (yday1, Y400_DAYS);
409 int leap;
410
411 if (overflow_sum_sign (tm.tm_year, pt->tmr.tm_year, years)
412 | overflow_sum_sign (tm.tm_mon, pt->tmr.tm_mon, mons)
413 | overflow_sum_sign (tm.tm_mday, pt->tmr.tm_mday, mdays)
414 | overflow_sum_sign (tm.tm_hour, pt->tmr.tm_hour, hours)
415 | overflow_sum_sign (tm.tm_min, pt->tmr.tm_min, mins)
416 | overflow_sum_sign (hours, carried_hours, hours1)
417 | overflow_sum_sign (mdays, carried_days, mdays1)
418 | overflow_sum_sign (years, carried_years0, year0)
419 | overflow_sum_sign (yday0, mdays1, yday1)
420 | overflow_sum_sign (year0, carried_years1, year1))
421 return -1;
422
423 for (;;)
424 {
425 int days_per_year = 365 + (leap = isleap (year1 + TM_YEAR_ORIGIN));
426 if (yday2 < days_per_year)
427 break;
428 yday2 -= days_per_year;
429 year1++;
430 }
431
432 tm.tm_year = year1;
433
434 {
435 int mon;
436 for (mon = 11;
437 (tm.tm_mday = (yday2 - month_yday[mon] + (mon < 2 || !leap))) <= 0;
438 mon--)
439 continue;
440 tm.tm_mon = mon;
441 }
442
443 tm.tm_hour = MOD (hours1, 24);
444 tm.tm_min = MOD (mins, 60);
445
446 r = tm2time (&tm, localzone);
447 if (r == -1)
448 return r;
449 }
450
451 /* Add the seconds' part of relative time. */
452 {
453 time_t rs = r + pt->tmr.tm_sec;
454 if ((pt->tmr.tm_sec < 0) != (rs < r))
455 return -1;
456 return rs;
457 }
458}
459
460/* Parse a free-format date in *SOURCE, yielding a Unix format time.
461 Update *SOURCE to point to the first character after the date.
462 If *SOURCE is missing some information, take defaults from
463 DEFAULT_TIME and DEFAULT_ZONE. *SOURCE may even be the empty
464 string or an immediately invalid string, in which case the default
465 time and zone is used.
466 Return (time_t) -1 if the time is invalid or cannot be represented. */
467time_t
468str2time (source, default_time, default_zone)
469 char const **source;
470 time_t default_time;
471 long default_zone;
472{
473 struct partime pt;
474
475 *source = partime (*source, &pt);
476 if (pt.zone == TM_UNDEFINED_ZONE)
477 pt.zone = default_zone;
478 return maketime (&pt, default_time);
479}
480
481#ifdef TEST
482#include <stdio.h>
483int
484main (argc, argv)
485 int argc;
486 char **argv;
487{
488 time_t default_time = time ((time_t *) 0);
489 long default_zone = argv[1] ? atol (argv[1]) : TM_LOCAL_ZONE;
490 char buf[1000];
491 while (fgets (buf, sizeof (buf), stdin))
492 {
493 char const *p = buf;
494 time_t t = str2time (&p, default_time, default_zone);
495 printf ("`%.*s' -> %s",
496 (int) (p - buf - (p[0] == '\0' && p[-1] == '\n')), buf,
497 asctime ((argv[1] ? gmtime : localtime) (&t)));
498 }
499 return 0;
500}
501#endif
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