source: unzip/vendor/current/timezone.c@ 200

Last change on this file since 200 was 200, checked in by Yuri Dario, 14 years ago

zip: initial unzip 6.0 import.
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1/*
2 Copyright (c) 1990-2001 Info-ZIP. All rights reserved.
3
4 See the accompanying file LICENSE, version 2000-Apr-09 or later
5 (the contents of which are also included in zip.h) for terms of use.
6 If, for some reason, all these files are missing, the Info-ZIP license
7 also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html
8*/
9/* Replacement time library functions, based on platform independent public
10 * domain timezone code from ftp://elsie.nci.nih.gov/pub, with mktime and
11 * mkgmtime from our own mktime.c in Zip.
12 *
13 * Contains: tzset()
14 * __tzset()
15 * gmtime()
16 * localtime()
17 * mktime()
18 * mkgmtime()
19 * GetPlatformLocalTimezone() [different versions]
20 */
21
22/* HISTORY/CHANGES
23 * 17 Jun 00, Paul Kienitz, added the PD-based tzset(), localtime(), and so on
24 * to amiga/filedate.c, replacing GNU-based functions which had
25 * replaced time_lib.c, both having been rejected for licensing
26 * reasons. Support for timezone files and leap seconds was removed.
27 *
28 * 23 Aug 00, Paul Kienitz, split into separate timezone.c file, made platform
29 * independent, copied in mktime() and mkgmtime() from Zip, renamed
30 * locale_TZ as GetPlatformLocalTimezone(), for use as a generic
31 * hook by other platforms.
32 */
33
34#ifndef __timezone_c
35#define __timezone_c
36
37
38#include "zip.h"
39#include "timezone.h"
40#include <ctype.h>
41#include <errno.h>
42
43#ifdef IZTZ_DEFINESTDGLOBALS
44long timezone = 0;
45int daylight = 0;
46char *tzname[2];
47#endif
48
49#ifndef IZTZ_GETLOCALETZINFO
50# define IZTZ_GETLOCALETZINFO(ptzstruct, pgenrulefunct) (FALSE)
51#endif
52
53int real_timezone_is_set = FALSE; /* set by tzset() */
54
55
56#define TZDEFRULESTRING ",M4.1.0,M10.5.0"
57#define TZDEFAULT "EST5EDT"
58
59#define SECSPERMIN 60
60#define MINSPERHOUR 60
61#define HOURSPERDAY 24
62#define DAYSPERWEEK 7
63#define DAYSPERNYEAR 365
64#define DAYSPERLYEAR 366
65#define SECSPERHOUR (SECSPERMIN * MINSPERHOUR)
66#define SECSPERDAY ((long) SECSPERHOUR * HOURSPERDAY)
67#define MONSPERYEAR 12
68
69#define EPOCH_WDAY 4 /* Jan 1, 1970 was thursday */
70#define EPOCH_YEAR 1970
71#define TM_YEAR_BASE 1900
72#define FIRST_GOOD_YEAR ((time_t) -1 < (time_t) 1 ? EPOCH_YEAR-68 : EPOCH_YEAR)
73#define LAST_GOOD_YEAR (EPOCH_YEAR + ((time_t) -1 < (time_t) 1 ? 67 : 135))
74
75#define YDAYS(month, year) yr_days[leap(year)][month]
76
77/* Nonzero if `y' is a leap year, else zero. */
78#define leap(y) (((y) % 4 == 0 && (y) % 100 != 0) || (y) % 400 == 0)
79
80/* Number of leap years from EPOCH_YEAR to `y' (not including `y' itself). */
81#define _P4 ((EPOCH_YEAR / 4) * 4 + 1)
82#define _P100 ((EPOCH_YEAR / 100) * 100 + 1)
83#define _P400 ((EPOCH_YEAR / 400) * 400 + 1)
84#define nleap(y) (((y) - _P4) / 4 - ((y) - _P100) / 100 + ((y) - _P400) / 400)
85
86/* Length of month `m' (0 .. 11) */
87#define monthlen(m, y) (yr_days[0][(m)+1] - yr_days[0][m] + \
88 ((m) == 1 && leap(y)))
89
90/* internal module-level constants */
91#ifndef IZ_MKTIME_ONLY
92static ZCONST char gmt[] = "GMT";
93static ZCONST int mon_lengths[2][MONSPERYEAR] = {
94 { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
95 { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
96};
97#endif /* !IZ_MKTIME_ONLY */
98static ZCONST int yr_days[2][MONSPERYEAR+1] = {
99 { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
100 { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
101};
102#ifndef IZ_MKTIME_ONLY
103static ZCONST int year_lengths[2] = {
104 DAYSPERNYEAR, DAYSPERLYEAR
105};
106
107/* internal variables */
108static struct state statism;
109
110
111/* prototypes of static functions */
112static time_t transtime OF((ZCONST time_t janfirst, ZCONST int year,
113 ZCONST struct rule * ZCONST rulep,
114 ZCONST long offset));
115static void generate_transitions OF((register struct state * ZCONST sp,
116 ZCONST struct rule * ZCONST start,
117 ZCONST struct rule * ZCONST end));
118static ZCONST char *getzname OF((ZCONST char *strp));
119static ZCONST char *getnum OF((ZCONST char *strp, int * ZCONST nump,
120 ZCONST int min, ZCONST int max));
121static ZCONST char *getsecs OF((ZCONST char *strp, long * ZCONST secsp));
122static ZCONST char *getoffset OF((ZCONST char *strp, long * ZCONST offsetp));
123static ZCONST char *getrule OF((ZCONST char *strp, struct rule * ZCONST rulep));
124static int Parse_TZ OF((ZCONST char *name, register struct state * ZCONST sp));
125
126
127static time_t transtime(janfirst, year, rulep, offset)
128 ZCONST time_t janfirst;
129 ZCONST int year;
130 ZCONST struct rule * ZCONST rulep;
131 ZCONST long offset;
132{
133 register int leapyear;
134 register time_t value;
135 register int i;
136 int d, m1, yy0, yy1, yy2, dow;
137
138 value = 0;
139 leapyear = leap(year);
140 switch (rulep->r_type) {
141
142 case JULIAN_DAY:
143 /*
144 ** Jn - Julian day, 1 == January 1, 60 == March 1 even in leap
145 ** years.
146 ** In non-leap years, or if the day number is 59 or less, just
147 ** add SECSPERDAY times the day number-1 to the time of
148 ** January 1, midnight, to get the day.
149 */
150 value = janfirst + (rulep->r_day - 1) * SECSPERDAY;
151 if (leapyear && rulep->r_day >= 60)
152 value += SECSPERDAY;
153 break;
154
155 case DAY_OF_YEAR:
156 /*
157 ** n - day of year.
158 ** Just add SECSPERDAY times the day number to the time of
159 ** January 1, midnight, to get the day.
160 */
161 value = janfirst + rulep->r_day * SECSPERDAY;
162 break;
163
164 case MONTH_NTH_DAY_OF_WEEK:
165 /*
166 ** Mm.n.d - nth "dth day" of month m.
167 */
168 value = janfirst;
169/*
170 for (i = 0; i < rulep->r_mon - 1; ++i)
171 value += mon_lengths[leapyear][i] * SECSPERDAY;
172*/
173 value += yr_days[leapyear][rulep->r_mon - 1] * SECSPERDAY;
174
175 /*
176 ** Use Zeller's Congruence to get day-of-week of first day of
177 ** month.
178 */
179 m1 = (rulep->r_mon + 9) % 12 + 1;
180 yy0 = (rulep->r_mon <= 2) ? (year - 1) : year;
181 yy1 = yy0 / 100;
182 yy2 = yy0 % 100;
183 dow = ((26 * m1 - 2) / 10 +
184 1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
185 if (dow < 0)
186 dow += DAYSPERWEEK;
187
188 /*
189 ** "dow" is the day-of-week of the first day of the month. Get
190 ** the day-of-month (zero-origin) of the first "dow" day of the
191 ** month.
192 */
193 d = rulep->r_day - dow;
194 if (d < 0)
195 d += DAYSPERWEEK;
196 for (i = 1; i < rulep->r_week; ++i) {
197 if (d + DAYSPERWEEK >= mon_lengths[leapyear][rulep->r_mon - 1])
198 break;
199 d += DAYSPERWEEK;
200 }
201
202 /*
203 ** "d" is the day-of-month (zero-origin) of the day we want.
204 */
205 value += d * SECSPERDAY;
206 break;
207 }
208
209 /*
210 ** "value" is the Epoch-relative time of 00:00:00 UTC on the day in
211 ** question. To get the Epoch-relative time of the specified local
212 ** time on that day, add the transition time and the current offset
213 ** from UTC.
214 */
215 return value + rulep->r_time + offset;
216}
217
218static void generate_transitions(sp, start, end)
219 register struct state * ZCONST sp;
220 ZCONST struct rule * ZCONST start;
221 ZCONST struct rule * ZCONST end;
222{
223 register int year;
224 register time_t janfirst;
225 time_t starttime;
226 time_t endtime;
227 long stdoffset = -sp->ttis[0].tt_gmtoff;
228 long dstoffset = -sp->ttis[1].tt_gmtoff;
229 register time_t * atp;
230 register unsigned char * typep;
231
232 /*
233 ** Two transitions per year, from EPOCH_YEAR to LAST_GOOD_YEAR.
234 */
235 sp->timecnt = 2 * (LAST_GOOD_YEAR - EPOCH_YEAR + 1);
236 atp = sp->ats;
237 typep = sp->types;
238 janfirst = 0;
239 for (year = EPOCH_YEAR; year <= LAST_GOOD_YEAR; ++year) {
240 starttime = transtime(janfirst, year, start, stdoffset);
241 endtime = transtime(janfirst, year, end, dstoffset);
242 if (starttime > endtime) {
243 *atp++ = endtime;
244 *typep++ = 0; /* DST ends */
245 *atp++ = starttime;
246 *typep++ = 1; /* DST begins */
247 } else {
248 *atp++ = starttime;
249 *typep++ = 1; /* DST begins */
250 *atp++ = endtime;
251 *typep++ = 0; /* DST ends */
252 }
253 janfirst += year_lengths[leap(year)] * SECSPERDAY;
254 }
255}
256
257static ZCONST char *getzname(strp)
258 ZCONST char *strp;
259{
260 register char c;
261
262 while ((c = *strp) != '\0' && !isdigit(c) && c != ',' && c != '-' &&
263 c != '+')
264 ++strp;
265 return strp;
266}
267
268static ZCONST char *getnum(strp, nump, min, max)
269 ZCONST char *strp;
270 int * ZCONST nump;
271 ZCONST int min;
272 ZCONST int max;
273{
274 register char c;
275 register int num;
276
277 if (strp == NULL || !isdigit(c = *strp))
278 return NULL;
279 num = 0;
280 do {
281 num = num * 10 + (c - '0');
282 if (num > max)
283 return NULL; /* illegal value */
284 c = *++strp;
285 } while (isdigit(c));
286 if (num < min)
287 return NULL; /* illegal value */
288 *nump = num;
289 return strp;
290}
291
292static ZCONST char *getsecs(strp, secsp)
293 ZCONST char *strp;
294 long * ZCONST secsp;
295{
296 int num;
297
298 /*
299 ** `HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like
300 ** "M10.4.6/26", which does not conform to Posix,
301 ** but which specifies the equivalent of
302 ** ``02:00 on the first Sunday on or after 23 Oct''.
303 */
304 strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1);
305 if (strp == NULL)
306 return NULL;
307 *secsp = num * (long) SECSPERHOUR;
308 if (*strp == ':') {
309 ++strp;
310 strp = getnum(strp, &num, 0, MINSPERHOUR - 1);
311 if (strp == NULL)
312 return NULL;
313 *secsp += num * SECSPERMIN;
314 if (*strp == ':') {
315 ++strp;
316 /* `SECSPERMIN' allows for leap seconds. */
317 strp = getnum(strp, &num, 0, SECSPERMIN);
318 if (strp == NULL)
319 return NULL;
320 *secsp += num;
321 }
322 }
323 return strp;
324}
325
326static ZCONST char *getoffset(strp, offsetp)
327 ZCONST char *strp;
328 long * ZCONST offsetp;
329{
330 register int neg = 0;
331
332 if (*strp == '-') {
333 neg = 1;
334 ++strp;
335 } else if (*strp == '+')
336 ++strp;
337 strp = getsecs(strp, offsetp);
338 if (strp == NULL)
339 return NULL; /* illegal time */
340 if (neg)
341 *offsetp = -*offsetp;
342 return strp;
343}
344
345static ZCONST char *getrule(strp, rulep)
346 ZCONST char *strp;
347 struct rule * ZCONST rulep;
348{
349 if (*strp == 'J') {
350 /*
351 ** Julian day.
352 */
353 rulep->r_type = JULIAN_DAY;
354 ++strp;
355 strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR);
356 } else if (*strp == 'M') {
357 /*
358 ** Month, week, day.
359 */
360 rulep->r_type = MONTH_NTH_DAY_OF_WEEK;
361 ++strp;
362 strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR);
363 if (strp == NULL)
364 return NULL;
365 if (*strp++ != '.')
366 return NULL;
367 strp = getnum(strp, &rulep->r_week, 1, 5);
368 if (strp == NULL)
369 return NULL;
370 if (*strp++ != '.')
371 return NULL;
372 strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1);
373 } else if (isdigit(*strp)) {
374 /*
375 ** Day of year.
376 */
377 rulep->r_type = DAY_OF_YEAR;
378 strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);
379 } else return NULL; /* invalid format */
380 if (strp == NULL)
381 return NULL;
382 if (*strp == '/') {
383 /*
384 ** Time specified.
385 */
386 ++strp;
387 strp = getsecs(strp, &rulep->r_time);
388 } else
389 rulep->r_time = 2 * SECSPERHOUR; /* default = 2:00:00 */
390 return strp;
391}
392
393static int Parse_TZ(name, sp)
394 ZCONST char *name;
395 register struct state * ZCONST sp;
396{
397 ZCONST char * stdname;
398 ZCONST char * dstname;
399 size_t stdlen;
400 size_t dstlen;
401 long stdoffset;
402 long dstoffset;
403 register char * cp;
404
405 dstname = NULL;
406 stdname = name;
407 name = getzname(name);
408 stdlen = name - stdname;
409 if (stdlen < 3)
410 return -1;
411 if (*name == '\0')
412 return -1;
413 name = getoffset(name, &stdoffset);
414 if (name == NULL)
415 return -1;
416 if (*name != '\0') {
417 dstname = name;
418 name = getzname(name);
419 dstlen = name - dstname; /* length of DST zone name */
420 if (dstlen < 3)
421 return -1;
422 if (*name != '\0' && *name != ',' && *name != ';') {
423 name = getoffset(name, &dstoffset);
424 if (name == NULL)
425 return -1;
426 } else
427 dstoffset = stdoffset - SECSPERHOUR;
428 if (*name == '\0')
429 name = TZDEFRULESTRING;
430 if (*name == ',' || *name == ';') {
431 struct rule start;
432 struct rule end;
433
434 ++name;
435 if ((name = getrule(name, &start)) == NULL)
436 return -1;
437 if (*name++ != ',')
438 return -1;
439 if ((name = getrule(name, &end)) == NULL)
440 return -1;
441 if (*name != '\0')
442 return -1;
443 sp->typecnt = 2; /* standard time and DST */
444 sp->ttis[0].tt_gmtoff = -stdoffset;
445 sp->ttis[0].tt_isdst = 0;
446 sp->ttis[0].tt_abbrind = 0;
447 sp->ttis[1].tt_gmtoff = -dstoffset;
448 sp->ttis[1].tt_isdst = 1;
449 sp->ttis[1].tt_abbrind = stdlen + 1;
450 generate_transitions(sp, &start, &end);
451 }
452 } else {
453 dstlen = 0;
454 sp->typecnt = 1; /* only standard time */
455 sp->timecnt = 0;
456 sp->ttis[0].tt_gmtoff = -stdoffset;
457 sp->ttis[0].tt_isdst = 0;
458 sp->ttis[0].tt_abbrind = 0;
459 }
460 sp->charcnt = stdlen + 1;
461 if (dstlen != 0)
462 sp->charcnt += dstlen + 1;
463 if ((size_t) sp->charcnt > sizeof(sp->chars))
464 return -1;
465 cp = sp->chars;
466 (void) strncpy(cp, stdname, stdlen);
467 cp += stdlen;
468 *cp++ = '\0';
469 if (dstlen != 0) {
470 (void) strncpy(cp, dstname, dstlen);
471 *(cp + dstlen) = '\0';
472 }
473 return 0;
474}
475
476void tzset()
477{
478 char *TZstring;
479 int dstfirst;
480 static char *old_TZstring = NULL;
481
482 TZstring = getenv("TZ"); /* read TZ envvar */
483 if (old_TZstring && TZstring && !strcmp(old_TZstring, TZstring))
484 /* do not repeatedly parse an unchanged TZ specification */
485 return;
486 if ((TZstring && TZstring[0] && Parse_TZ(TZstring, &statism) == 0)
487 || IZTZ_GETLOCALETZINFO(&statism, generate_transitions)
488 || Parse_TZ(gmt, &statism) == 0) {
489 daylight = statism.typecnt > 1;
490 dstfirst = daylight && statism.ttis[0].tt_isdst && !statism.ttis[1].tt_isdst;
491 timezone = -statism.ttis[dstfirst].tt_gmtoff;
492 tzname[0] = statism.chars + statism.ttis[dstfirst].tt_abbrind;
493 tzname[1] = statism.chars + statism.ttis[!dstfirst].tt_abbrind;
494 real_timezone_is_set = TRUE;
495 if (TZstring) {
496 if (old_TZstring)
497 old_TZstring = realloc(old_TZstring, strlen(TZstring) + 1);
498 else
499 old_TZstring = malloc(strlen(TZstring) + 1);
500 if (old_TZstring)
501 strcpy(old_TZstring, TZstring);
502 }
503 } else {
504 timezone = 0; /* default is GMT0 which means no offsets */
505 daylight = 0; /* from local system time */
506 real_timezone_is_set = FALSE;
507 if (old_TZstring) {
508 free(old_TZstring);
509 old_TZstring = NULL;
510 }
511 }
512#ifdef IZTZ_SETLOCALTZINFO
513 /* Some SAS/C library functions, e.g. stat(), call library */
514 /* __tzset() themselves. So envvar TZ *must* exist in order to */
515 /* to get the right offset from GMT. XXX TRY HARD to fix this! */
516 set_TZ(timezone, daylight);
517#endif /* IZTZ_SETLOCALTZINFO */
518}
519
520/* XXX Does this also help SAS/C library work? */
521void __tzset()
522{
523 if (!real_timezone_is_set) tzset();
524}
525
526static struct tm _tmbuf;
527
528struct tm *gmtime(when)
529 ZCONST time_t *when;
530{
531 long days = *when / SECSPERDAY;
532 long secs = *when % SECSPERDAY;
533 int isleap;
534
535 memset(&_tmbuf, 0, sizeof(_tmbuf)); /* get any nonstandard fields */
536 _tmbuf.tm_wday = (days + EPOCH_WDAY) % 7;
537 _tmbuf.tm_year = EPOCH_YEAR - TM_YEAR_BASE;
538 isleap = leap(_tmbuf.tm_year + TM_YEAR_BASE);
539 while (days >= year_lengths[isleap]) {
540 days -= year_lengths[isleap];
541 _tmbuf.tm_year++;
542 isleap = leap(_tmbuf.tm_year + TM_YEAR_BASE);
543 }
544 _tmbuf.tm_mon = 0;
545 _tmbuf.tm_yday = days;
546 while (days >= mon_lengths[isleap][_tmbuf.tm_mon])
547 days -= mon_lengths[isleap][_tmbuf.tm_mon++];
548 _tmbuf.tm_mday = days + 1;
549 _tmbuf.tm_isdst = 0;
550 _tmbuf.tm_sec = secs % SECSPERMIN;
551 _tmbuf.tm_min = (secs / SECSPERMIN) % SECSPERMIN;
552 _tmbuf.tm_hour = secs / SECSPERHOUR;
553 return &_tmbuf;
554}
555
556struct tm *localtime(when)
557 ZCONST time_t *when;
558{
559 time_t localwhen = *when;
560 int timetype;
561 struct tm *ret;
562
563 __tzset();
564 if (statism.timecnt == 0 || localwhen < statism.ats[0])
565 timetype = statism.ttis[0].tt_isdst && statism.typecnt > 1 &&
566 !statism.ttis[1].tt_isdst;
567 else {
568 for (timetype = 1; timetype < statism.timecnt; ++timetype)
569 if (localwhen < statism.ats[timetype])
570 break;
571 timetype = statism.types[timetype - 1];
572 }
573 localwhen += statism.ttis[timetype].tt_gmtoff;
574 ret = gmtime(&localwhen);
575 ret->tm_isdst = statism.ttis[timetype].tt_isdst;
576 return ret;
577}
578
579#ifdef NEED__ISINDST
580int _isindst(tb)
581 struct tm *tb;
582{
583 time_t localt; /* time_t equivalent of given tm struct */
584 time_t univt; /* assumed UTC value of given time */
585 long tzoffset_adj; /* timezone-adjustment `remainder' */
586 int bailout_cnt; /* counter of tries for tz correction */
587 int timetype;
588
589 __tzset();
590
591 /* when DST is unsupported in current timezone, DST is always off */
592 if (statism.typecnt <= 1) return FALSE;
593
594 localt = mkgmtime(tb);
595 if (localt == (time_t)-1)
596 /* specified time is out-of-range, default to FALSE */
597 return FALSE;
598
599 univt = localt - statism.ttis[0].tt_gmtoff;
600 bailout_cnt = 3;
601 do {
602 if (statism.timecnt == 0 || univt < statism.ats[0])
603 timetype = statism.ttis[0].tt_isdst && statism.typecnt > 1 &&
604 !statism.ttis[1].tt_isdst;
605 else {
606 for (timetype = 1; timetype < statism.timecnt; ++timetype)
607 if (univt < statism.ats[timetype])
608 break;
609 timetype = statism.types[timetype - 1];
610 }
611 if ((tzoffset_adj = localt - univt - statism.ttis[timetype].tt_gmtoff)
612 == 0L)
613 break;
614 univt += tzoffset_adj;
615 } while (--bailout_cnt > 0);
616
617 /* return TRUE when DST is active at given time */
618 return (statism.ttis[timetype].tt_isdst);
619}
620#endif /* NEED__ISINDST */
621#endif /* !IZ_MKTIME_ONLY */
622
623/* Return the equivalent in seconds past 12:00:00 a.m. Jan 1, 1970 GMT
624 of the local time and date in the exploded time structure `tm',
625 adjust out of range fields in `tm' and set `tm->tm_yday', `tm->tm_wday'.
626 If `tm->tm_isdst < 0' was passed to mktime(), the correct setting of
627 tm_isdst is determined and returned. Otherwise, mktime() assumes this
628 field as valid; its information is used when converting local time
629 to UTC.
630 Return -1 if time in `tm' cannot be represented as time_t value. */
631
632time_t mktime(tm)
633 struct tm *tm;
634{
635 struct tm *ltm; /* Local time. */
636 time_t loctime; /* The time_t value of local time. */
637 time_t then; /* The time to return. */
638 long tzoffset_adj; /* timezone-adjustment `remainder' */
639 int bailout_cnt; /* counter of tries for tz correction */
640 int save_isdst; /* Copy of the tm->isdst input value */
641
642 save_isdst = tm->tm_isdst;
643 loctime = mkgmtime(tm);
644 if (loctime == -1) {
645 tm->tm_isdst = save_isdst;
646 return (time_t)-1;
647 }
648
649 /* Correct for the timezone and any daylight savings time.
650 The correction is verified and repeated when not correct, to
651 take into account the rare case that a change to or from daylight
652 savings time occurs between when it is the time in `tm' locally
653 and when it is that time in Greenwich. After the second correction,
654 the "timezone & daylight" offset should be correct in all cases. To
655 be sure, we allow a third try, but then the loop is stopped. */
656 bailout_cnt = 3;
657 then = loctime;
658 do {
659 ltm = localtime(&then);
660 if (ltm == (struct tm *)NULL ||
661 (tzoffset_adj = loctime - mkgmtime(ltm)) == 0L)
662 break;
663 then += tzoffset_adj;
664 } while (--bailout_cnt > 0);
665
666 if (ltm == (struct tm *)NULL || tzoffset_adj != 0L) {
667 /* Signal failure if timezone adjustment did not converge. */
668 tm->tm_isdst = save_isdst;
669 return (time_t)-1;
670 }
671
672 if (save_isdst >= 0) {
673 if (ltm->tm_isdst && !save_isdst)
674 {
675 if (then + 3600 < then)
676 then = (time_t)-1;
677 else
678 then += 3600;
679 }
680 else if (!ltm->tm_isdst && save_isdst)
681 {
682 if (then - 3600 > then)
683 then = (time_t)-1;
684 else
685 then -= 3600;
686 }
687 ltm->tm_isdst = save_isdst;
688 }
689
690 if (tm != ltm) /* `tm' may already point to localtime's internal storage */
691 *tm = *ltm;
692
693 return then;
694}
695
696
697#ifndef NO_TIME_T_MAX
698 /* Provide default values for the upper limit of the time_t range.
699 These are the result of the decomposition into a `struct tm' for
700 the time value 0xFFFFFFFEL ( = (time_t)-2 ).
701 Note: `(time_t)-1' is reserved for "invalid time"! */
702# ifndef TM_YEAR_MAX
703# define TM_YEAR_MAX 2106
704# endif
705# ifndef TM_MON_MAX
706# define TM_MON_MAX 1 /* February */
707# endif
708# ifndef TM_MDAY_MAX
709# define TM_MDAY_MAX 7
710# endif
711# ifndef TM_HOUR_MAX
712# define TM_HOUR_MAX 6
713# endif
714# ifndef TM_MIN_MAX
715# define TM_MIN_MAX 28
716# endif
717# ifndef TM_SEC_MAX
718# define TM_SEC_MAX 14
719# endif
720#endif /* NO_TIME_T_MAX */
721
722/* Adjusts out-of-range values for `tm' field `tm_member'. */
723#define ADJUST_TM(tm_member, tm_carry, modulus) \
724 if ((tm_member) < 0) { \
725 tm_carry -= (1 - ((tm_member)+1) / (modulus)); \
726 tm_member = (modulus-1) + (((tm_member)+1) % (modulus)); \
727 } else if ((tm_member) >= (modulus)) { \
728 tm_carry += (tm_member) / (modulus); \
729 tm_member = (tm_member) % (modulus); \
730 }
731
732/* Return the equivalent in seconds past 12:00:00 a.m. Jan 1, 1970 GMT
733 of the Greenwich Mean time and date in the exploded time structure `tm'.
734 This function does always put back normalized values into the `tm' struct,
735 parameter, including the calculated numbers for `tm->tm_yday',
736 `tm->tm_wday', and `tm->tm_isdst'.
737 Returns -1 if the time in the `tm' parameter cannot be represented
738 as valid `time_t' number. */
739
740time_t mkgmtime(tm)
741 struct tm *tm;
742{
743 int years, months, days, hours, minutes, seconds;
744
745 years = tm->tm_year + TM_YEAR_BASE; /* year - 1900 -> year */
746 months = tm->tm_mon; /* 0..11 */
747 days = tm->tm_mday - 1; /* 1..31 -> 0..30 */
748 hours = tm->tm_hour; /* 0..23 */
749 minutes = tm->tm_min; /* 0..59 */
750 seconds = tm->tm_sec; /* 0..61 in ANSI C. */
751
752 ADJUST_TM(seconds, minutes, 60)
753 ADJUST_TM(minutes, hours, 60)
754 ADJUST_TM(hours, days, 24)
755 ADJUST_TM(months, years, 12)
756 if (days < 0)
757 do {
758 if (--months < 0) {
759 --years;
760 months = 11;
761 }
762 days += monthlen(months, years);
763 } while (days < 0);
764 else
765 while (days >= monthlen(months, years)) {
766 days -= monthlen(months, years);
767 if (++months >= 12) {
768 ++years;
769 months = 0;
770 }
771 }
772
773 /* Restore adjusted values in tm structure */
774 tm->tm_year = years - TM_YEAR_BASE;
775 tm->tm_mon = months;
776 tm->tm_mday = days + 1;
777 tm->tm_hour = hours;
778 tm->tm_min = minutes;
779 tm->tm_sec = seconds;
780
781 /* Set `days' to the number of days into the year. */
782 days += YDAYS(months, years);
783 tm->tm_yday = days;
784
785 /* Now calculate `days' to the number of days since Jan 1, 1970. */
786 days = (unsigned)days + 365 * (unsigned)(years - EPOCH_YEAR) +
787 (unsigned)(nleap (years));
788 tm->tm_wday = ((unsigned)days + EPOCH_WDAY) % 7;
789 tm->tm_isdst = 0;
790
791 if (years < EPOCH_YEAR)
792 return (time_t)-1;
793
794#if (defined(TM_YEAR_MAX) && defined(TM_MON_MAX) && defined(TM_MDAY_MAX))
795#if (defined(TM_HOUR_MAX) && defined(TM_MIN_MAX) && defined(TM_SEC_MAX))
796 if (years > TM_YEAR_MAX ||
797 (years == TM_YEAR_MAX &&
798 (tm->tm_yday > (YDAYS(TM_MON_MAX, TM_YEAR_MAX) + (TM_MDAY_MAX - 1)) ||
799 (tm->tm_yday == (YDAYS(TM_MON_MAX, TM_YEAR_MAX) + (TM_MDAY_MAX - 1)) &&
800 (hours > TM_HOUR_MAX ||
801 (hours == TM_HOUR_MAX &&
802 (minutes > TM_MIN_MAX ||
803 (minutes == TM_MIN_MAX && seconds > TM_SEC_MAX) )))))))
804 return (time_t)-1;
805#endif
806#endif
807
808 return (time_t)(SECSPERDAY * (unsigned long)(unsigned)days +
809 SECSPERHOUR * (unsigned long)hours +
810 (unsigned long)(SECSPERMIN * minutes + seconds));
811}
812
813#endif /* __timezone_c */
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