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Bring in some fixes from tzdata2009a from elsie.
[dragonfly.git] / lib / libc / stdtime / strftime.c
blob455dbd3a4fceeffc143992c4a7c0976818c2e397
1 /*
2 * @(#)strftime.c 8.3
3 * $NetBSD: src/lib/libc/time/strftime.c,v 1.16 2004/05/12 23:03:11 kleink Exp $
4 * $DragonFly: src/lib/libc/stdtime/strftime.c,v 1.7 2008/10/19 20:15:58 swildner Exp $
5 */
6
7 /*
8 ** Based on the UCB version with the ID appearing below.
9 ** This is ANSIish only when "multibyte character == plain character".
10 */
11
12 /*
13 ** We don't use these extensions in strftime operation even when
14 ** supported by the local tzcode configuration. A strictly
15 ** conforming C application may leave them in undefined state.
16 */
17
18 #ifdef _LIBC
19 #undef TM_ZONE
20 #undef TM_GMTOFF
21 #endif
22
23 /*
24 ** Copyright (c) 1989, 1993
25 ** The Regents of the University of California. All rights reserved.
26 **
27 ** Redistribution and use in source and binary forms, with or without
28 ** modification, are permitted provided that the following conditions
29 ** are met:
30 ** 1. Redistributions of source code must retain the above copyright
31 ** notice, this list of conditions and the following disclaimer.
32 ** 2. Redistributions in binary form must reproduce the above copyright
33 ** notice, this list of conditions and the following disclaimer in the
34 ** documentation and/or other materials provided with the distribution.
35 ** 3. All advertising materials mentioning features or use of this software
36 ** must display the following acknowledgement:
37 ** This product includes software developed by the University of
38 ** California, Berkeley and its contributors.
39 ** 4. Neither the name of the University nor the names of its contributors
40 ** may be used to endorse or promote products derived from this software
41 ** without specific prior written permission.
42 **
43 ** THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
44 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
45 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
46 ** ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
47 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
48 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
49 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
50 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
51 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
52 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
53 ** SUCH DAMAGE.
54 */
55
56 #include <sys/localedef.h>
57 #include <fcntl.h>
58 #include <locale.h>
59 #include <time.h>
60
61 #include "private.h"
62 #include "tzfile.h"
63
64 #define Locale _CurrentTimeLocale
65
66 static char * _add(const char *, char *, const char *);
67 static char * _conv(int, const char *, char *, const char *);
68 static char * _fmt(const char *, const struct tm *, char *,
69 const char *, int *);
70 static char * _yconv(int, int, int, int, char *, const char *);
71
72 #define NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
73
74 #ifndef YEAR_2000_NAME
75 #define YEAR_2000_NAME "CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
76 #endif /* !defined YEAR_2000_NAME */
77
78 #define IN_NONE 0
79 #define IN_SOME 1
80 #define IN_THIS 2
81 #define IN_ALL 3
82
83 size_t
84 strftime(char * const s, const size_t maxsize, const char * const format,
85 const struct tm * const t)
86 {
87 char * p;
88 int warn;
89
90 tzset();
91 warn = IN_NONE;
92 p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn);
93 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
94 if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
95 fprintf(stderr, "\n");
96 if (format == NULL)
97 fprintf(stderr, "NULL strftime format ");
98 else fprintf(stderr, "strftime format \"%s\" ",
99 format);
100 fprintf(stderr, "yields only two digits of years in ");
101 if (warn == IN_SOME)
102 fprintf(stderr, "some locales");
103 else if (warn == IN_THIS)
104 fprintf(stderr, "the current locale");
105 else fprintf(stderr, "all locales");
106 fprintf(stderr, "\n");
107 }
108 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
109 if (p == s + maxsize)
110 return 0;
111 *p = '\0';
112 return p - s;
113 }
114
115 static char *
116 _fmt(const char *format, const struct tm * const t, char *pt,
117 const char * const ptlim, int * warnp)
118 {
119 for ( ; *format; ++format) {
120 if (*format == '%') {
121 label:
122 switch (*++format) {
123 case '\0':
124 --format;
125 break;
126 case 'A':
127 pt = _add((t->tm_wday < 0 ||
128 t->tm_wday >= DAYSPERWEEK) ?
129 "?" : Locale->day[t->tm_wday],
130 pt, ptlim);
131 continue;
132 case 'a':
133 pt = _add((t->tm_wday < 0 ||
134 t->tm_wday >= DAYSPERWEEK) ?
135 "?" : Locale->abday[t->tm_wday],
136 pt, ptlim);
137 continue;
138 case 'B':
139 pt = _add((t->tm_mon < 0 ||
140 t->tm_mon >= MONSPERYEAR) ?
141 "?" : Locale->mon[t->tm_mon],
142 pt, ptlim);
143 continue;
144 case 'b':
145 case 'h':
146 pt = _add((t->tm_mon < 0 ||
147 t->tm_mon >= MONSPERYEAR) ?
148 "?" : Locale->abmon[t->tm_mon],
149 pt, ptlim);
150 continue;
151 case 'C':
152 /*
153 ** %C used to do a...
154 ** _fmt("%a %b %e %X %Y", t);
155 ** ...whereas now POSIX 1003.2 calls for
156 ** something completely different.
157 ** (ado, 1993-05-24)
158 */
159 pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 0,
160 pt, ptlim);
161 continue;
162 case 'c':
163 {
164 int warn2 = IN_SOME;
165
166 pt = _fmt(Locale->d_t_fmt, t, pt, ptlim, &warn2);
167 if (warn2 == IN_ALL)
168 warn2 = IN_THIS;
169 if (warn2 > *warnp)
170 *warnp = warn2;
171 }
172 continue;
173 case 'D':
174 pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
175 continue;
176 case 'd':
177 pt = _conv(t->tm_mday, "%02d", pt, ptlim);
178 continue;
179 case 'E':
180 case 'O':
181 /*
182 ** C99 locale modifiers.
183 ** The sequences
184 ** %Ec %EC %Ex %EX %Ey %EY
185 ** %Od %oe %OH %OI %Om %OM
186 ** %OS %Ou %OU %OV %Ow %OW %Oy
187 ** are supposed to provide alternate
188 ** representations.
189 */
190 goto label;
191 case 'e':
192 pt = _conv(t->tm_mday, "%2d", pt, ptlim);
193 continue;
194 case 'F':
195 pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
196 continue;
197 case 'H':
198 pt = _conv(t->tm_hour, "%02d", pt, ptlim);
199 continue;
200 case 'I':
201 pt = _conv((t->tm_hour % 12) ?
202 (t->tm_hour % 12) : 12,
203 "%02d", pt, ptlim);
204 continue;
205 case 'j':
206 pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
207 continue;
208 case 'k':
209 /*
210 ** This used to be...
211 ** _conv(t->tm_hour % 12 ?
212 ** t->tm_hour % 12 : 12, 2, ' ');
213 ** ...and has been changed to the below to
214 ** match SunOS 4.1.1 and Arnold Robbins'
215 ** strftime version 3.0. That is, "%k" and
216 ** "%l" have been swapped.
217 ** (ado, 1993-05-24)
218 */
219 pt = _conv(t->tm_hour, "%2d", pt, ptlim);
220 continue;
221 #ifdef KITCHEN_SINK
222 case 'K':
223 /*
224 ** After all this time, still unclaimed!
225 */
226 pt = _add("kitchen sink", pt, ptlim);
227 continue;
228 #endif /* defined KITCHEN_SINK */
229 case 'l':
230 /*
231 ** This used to be...
232 ** _conv(t->tm_hour, 2, ' ');
233 ** ...and has been changed to the below to
234 ** match SunOS 4.1.1 and Arnold Robbin's
235 ** strftime version 3.0. That is, "%k" and
236 ** "%l" have been swapped.
237 ** (ado, 1993-05-24)
238 */
239 pt = _conv((t->tm_hour % 12) ?
240 (t->tm_hour % 12) : 12,
241 "%2d", pt, ptlim);
242 continue;
243 case 'M':
244 pt = _conv(t->tm_min, "%02d", pt, ptlim);
245 continue;
246 case 'm':
247 pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
248 continue;
249 case 'n':
250 pt = _add("\n", pt, ptlim);
251 continue;
252 case 'p':
253 pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
254 Locale->am_pm[1] :
255 Locale->am_pm[0],
256 pt, ptlim);
257 continue;
258 case 'R':
259 pt = _fmt("%H:%M", t, pt, ptlim, warnp);
260 continue;
261 case 'r':
262 pt = _fmt("%I:%M:%S %p", t, pt, ptlim, warnp);
263 continue;
264 case 'S':
265 pt = _conv(t->tm_sec, "%02d", pt, ptlim);
266 continue;
267 case 's':
268 {
269 struct tm tm;
270 char buf[INT_STRLEN_MAXIMUM(
271 time_t) + 1];
272 time_t mkt;
273
274 tm = *t;
275 mkt = mktime(&tm);
276 /* CONSTCOND */
277 if (TYPE_SIGNED(time_t))
278 sprintf(buf, "%ld",
279 (long) mkt);
280 else sprintf(buf, "%lu",
281 (unsigned long) mkt);
282 pt = _add(buf, pt, ptlim);
283 }
284 continue;
285 case 'T':
286 pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
287 continue;
288 case 't':
289 pt = _add("\t", pt, ptlim);
290 continue;
291 case 'U':
292 pt = _conv((t->tm_yday + DAYSPERWEEK -
293 t->tm_wday) / DAYSPERWEEK,
294 "%02d", pt, ptlim);
295 continue;
296 case 'u':
297 /*
298 ** From Arnold Robbins' strftime version 3.0:
299 ** "ISO 8601: Weekday as a decimal number
300 ** [1 (Monday) - 7]"
301 ** (ado, 1993-05-24)
302 */
303 pt = _conv((t->tm_wday == 0) ?
304 DAYSPERWEEK : t->tm_wday,
305 "%d", pt, ptlim);
306 continue;
307 case 'V': /* ISO 8601 week number */
308 case 'G': /* ISO 8601 year (four digits) */
309 case 'g': /* ISO 8601 year (two digits) */
310 /*
311 ** From Arnold Robbins' strftime version 3.0: "the week number of the
312 ** year (the first Monday as the first day of week 1) as a decimal number
313 ** (01-53)."
314 ** (ado, 1993-05-24)
315 **
316 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
317 ** "Week 01 of a year is per definition the first week which has the
318 ** Thursday in this year, which is equivalent to the week which contains
319 ** the fourth day of January. In other words, the first week of a new year
320 ** is the week which has the majority of its days in the new year. Week 01
321 ** might also contain days from the previous year and the week before week
322 ** 01 of a year is the last week (52 or 53) of the previous year even if
323 ** it contains days from the new year. A week starts with Monday (day 1)
324 ** and ends with Sunday (day 7). For example, the first week of the year
325 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
326 ** (ado, 1996-01-02)
327 */
328 {
329 int year;
330 int base;
331 int yday;
332 int wday;
333 int w;
334
335 year = t->tm_year;
336 base = TM_YEAR_BASE;
337 yday = t->tm_yday;
338 wday = t->tm_wday;
339 for ( ; ; ) {
340 int len;
341 int bot;
342 int top;
343
344 len = isleap_sum(year, base) ?
345 DAYSPERLYEAR :
346 DAYSPERNYEAR;
347 /*
348 ** What yday (-3 ... 3) does
349 ** the ISO year begin on?
350 */
351 bot = ((yday + 11 - wday) %
352 DAYSPERWEEK) - 3;
353 /*
354 ** What yday does the NEXT
355 ** ISO year begin on?
356 */
357 top = bot -
358 (len % DAYSPERWEEK);
359 if (top < -3)
360 top += DAYSPERWEEK;
361 top += len;
362 if (yday >= top) {
363 ++base;
364 w = 1;
365 break;
366 }
367 if (yday >= bot) {
368 w = 1 + ((yday - bot) /
369 DAYSPERWEEK);
370 break;
371 }
372 --base;
373 yday += isleap_sum(year, base) ?
374 DAYSPERLYEAR :
375 DAYSPERNYEAR;
376 }
377 #ifdef XPG4_1994_04_09
378 if ((w == 52 &&
379 t->tm_mon == TM_JANUARY) ||
380 (w == 1 &&
381 t->tm_mon == TM_DECEMBER))
382 w = 53;
383 #endif /* defined XPG4_1994_04_09 */
384 if (*format == 'V')
385 pt = _conv(w, "%02d",
386 pt, ptlim);
387 else if (*format == 'g') {
388 *warnp = IN_ALL;
389 pt = _yconv(year, base, 0, 1,
390 pt, ptlim);
391 } else pt = _yconv(year, base, 1, 1,
392 pt, ptlim);
393 }
394 continue;
395 case 'v':
396 /*
397 ** From Arnold Robbins' strftime version 3.0:
398 ** "date as dd-bbb-YYYY"
399 ** (ado, 1993-05-24)
400 */
401 pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
402 continue;
403 case 'W':
404 pt = _conv((t->tm_yday + DAYSPERWEEK -
405 (t->tm_wday ?
406 (t->tm_wday - 1) :
407 (DAYSPERWEEK - 1))) / DAYSPERWEEK,
408 "%02d", pt, ptlim);
409 continue;
410 case 'w':
411 pt = _conv(t->tm_wday, "%d", pt, ptlim);
412 continue;
413 case 'X':
414 pt = _fmt(Locale->t_fmt, t, pt, ptlim, warnp);
415 continue;
416 case 'x':
417 {
418 int warn2 = IN_SOME;
419
420 pt = _fmt(Locale->d_fmt, t, pt, ptlim, &warn2);
421 if (warn2 == IN_ALL)
422 warn2 = IN_THIS;
423 if (warn2 > *warnp)
424 *warnp = warn2;
425 }
426 continue;
427 case 'y':
428 *warnp = IN_ALL;
429 pt = _yconv(t->tm_year, TM_YEAR_BASE, 0, 1,
430 pt, ptlim);
431 continue;
432 case 'Y':
433 pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 1,
434 pt, ptlim);
435 continue;
436 case 'Z':
437 #ifdef TM_ZONE
438 if (t->TM_ZONE != NULL)
439 pt = _add(t->TM_ZONE, pt, ptlim);
440 else
441 #endif /* defined TM_ZONE */
442 if (t->tm_isdst >= 0)
443 pt = _add(tzname[t->tm_isdst != 0],
444 pt, ptlim);
445 /*
446 ** C99 says that %Z must be replaced by the
447 ** empty string if the time zone is not
448 ** determinable.
449 */
450 continue;
451 case 'z':
452 {
453 int diff;
454 char const * sign;
455
456 if (t->tm_isdst < 0)
457 continue;
458 #ifdef TM_GMTOFF
459 diff = (int)t->TM_GMTOFF;
460 #else /* !defined TM_GMTOFF */
461 /*
462 ** C99 says that the UTC offset must
463 ** be computed by looking only at
464 ** tm_isdst. This requirement is
465 ** incorrect, since it means the code
466 ** must rely on magic (in this case
467 ** altzone and timezone), and the
468 ** magic might not have the correct
469 ** offset. Doing things correctly is
470 ** tricky and requires disobeying C99;
471 ** see GNU C strftime for details.
472 ** For now, punt and conform to the
473 ** standard, even though it's incorrect.
474 **
475 ** C99 says that %z must be replaced by the
476 ** empty string if the time zone is not
477 ** determinable, so output nothing if the
478 ** appropriate variables are not available.
479 */
480 #ifndef STD_INSPIRED
481 if (t->tm_isdst == 0)
482 #ifdef USG_COMPAT
483 diff = -timezone;
484 #else /* !defined USG_COMPAT */
485 continue;
486 #endif /* !defined USG_COMPAT */
487 else
488 #ifdef ALTZONE
489 diff = -altzone;
490 #else /* !defined ALTZONE */
491 continue;
492 #endif /* !defined ALTZONE */
493 #else /* defined STD_INSPIRED */
494 {
495 struct tm tmp;
496 time_t lct, gct;
497
498 /*
499 ** Get calendar time from t
500 ** being treated as local.
501 */
502 tmp = *t; /* mktime discards const */
503 lct = mktime(&tmp);
504
505 if (lct == (time_t)-1)
506 continue;
507
508 /*
509 ** Get calendar time from t
510 ** being treated as GMT.
511 **/
512 tmp = *t; /* mktime discards const */
513 gct = timegm(&tmp);
514
515 if (gct == (time_t)-1)
516 continue;
517
518 /* LINTED difference will fit int */
519 diff = (intmax_t)gct - (intmax_t)lct;
520 }
521 #endif /* defined STD_INSPIRED */
522 #endif /* !defined TM_GMTOFF */
523 if (diff < 0) {
524 sign = "-";
525 diff = -diff;
526 } else sign = "+";
527 pt = _add(sign, pt, ptlim);
528 diff /= SECSPERMIN;
529 diff = (diff / MINSPERHOUR) * 100 +
530 (diff % MINSPERHOUR);
531 pt = _conv(diff, "%04d", pt, ptlim);
532 }
533 continue;
534 case '+':
535 pt = _fmt(Locale->d_t_fmt, t, pt, ptlim,
536 warnp);
537 continue;
538 case '%':
539 /*
540 ** X311J/88-090 (4.12.3.5): if conversion char is
541 ** undefined, behavior is undefined. Print out the
542 ** character itself as printf(3) also does.
543 */
544 default:
545 break;
546 }
547 }
548 if (pt == ptlim)
549 break;
550 *pt++ = *format;
551 }
552 return pt;
553 }
554
555 static char *
556 _conv(const int n, const char * const format, char * const pt,
557 const char * const ptlim)
558 {
559 char buf[INT_STRLEN_MAXIMUM(int) + 1];
560
561 sprintf(buf, format, n);
562 return _add(buf, pt, ptlim);
563 }
564
565 static char *
566 _add(const char *str, char *pt, const char * const ptlim)
567 {
568 while (pt < ptlim && (*pt = *str++) != '\0')
569 ++pt;
570 return pt;
571 }
572
573 /*
574 ** POSIX and the C Standard are unclear or inconsistent about
575 ** what %C and %y do if the year is negative or exceeds 9999.
576 ** Use the convention that %C concatenated with %y yields the
577 ** same output as %Y, and that %Y contains at least 4 bytes,
578 ** with more only if necessary.
579 */
580
581 static char *
582 _yconv(const int a, const int b, const int convert_top, const int convert_yy,
583 char *pt, const char * const ptlim)
584 {
585 int lead;
586 int trail;
587
588 #define DIVISOR 100
589 trail = a % DIVISOR + b % DIVISOR;
590 lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
591 trail %= DIVISOR;
592 if (trail < 0 && lead > 0) {
593 trail += DIVISOR;
594 --lead;
595 } else if (lead < 0 && trail > 0) {
596 trail -= DIVISOR;
597 ++lead;
598 }
599 if (convert_top) {
600 if (lead == 0 && trail < 0)
601 pt = _add("-0", pt, ptlim);
602 else pt = _conv(lead, "%02d", pt, ptlim);
603 }
604 if (convert_yy)
605 pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
606 return pt;
607 }
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