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[dragonfly.git] / lib / libc / stdtime / strftime.c
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1 /* $NetBSD: src/lib/libc/time/strftime.c,v 1.16 2004/05/12 23:03:11 kleink Exp $ */
2 /* $DragonFly: src/lib/libc/stdtime/strftime.c,v 1.6 2005/12/04 23:25:40 swildner Exp $ */
3
4 /*
5 ** Based on the UCB version with the ID appearing below.
6 ** This is ANSIish only when "multibyte character == plain character".
7 */
8
9 /*
10 ** We don't use these extensions in strftime operation even when
11 ** supported by the local tzcode configuration. A strictly
12 ** conforming C application may leave them in undefined state.
13 */
14
15 #ifdef _LIBC
16 #undef TM_ZONE
17 #undef TM_GMTOFF
18 #endif
19
20 /*
21 ** Copyright (c) 1989, 1993
22 ** The Regents of the University of California. All rights reserved.
23 **
24 ** Redistribution and use in source and binary forms, with or without
25 ** modification, are permitted provided that the following conditions
26 ** are met:
27 ** 1. Redistributions of source code must retain the above copyright
28 ** notice, this list of conditions and the following disclaimer.
29 ** 2. Redistributions in binary form must reproduce the above copyright
30 ** notice, this list of conditions and the following disclaimer in the
31 ** documentation and/or other materials provided with the distribution.
32 ** 3. All advertising materials mentioning features or use of this software
33 ** must display the following acknowledgement:
34 ** This product includes software developed by the University of
35 ** California, Berkeley and its contributors.
36 ** 4. Neither the name of the University nor the names of its contributors
37 ** may be used to endorse or promote products derived from this software
38 ** without specific prior written permission.
39 **
40 ** THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
41 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 ** ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
44 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50 ** SUCH DAMAGE.
51 */
52
53 #include <sys/localedef.h>
54 #include <fcntl.h>
55 #include <locale.h>
56 #include <time.h>
57
58 #include "private.h"
59 #include "tzfile.h"
60
61 #define Locale _CurrentTimeLocale
62
63 static char * _add(const char *, char *, const char *);
64 static char * _conv(int, const char *, char *, const char *);
65 static char * _fmt(const char *, const struct tm *, char *,
66 const char *, int *);
67
68 #define NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
69
70 #ifndef YEAR_2000_NAME
71 #define YEAR_2000_NAME "CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
72 #endif /* !defined YEAR_2000_NAME */
73
74
75 #define IN_NONE 0
76 #define IN_SOME 1
77 #define IN_THIS 2
78 #define IN_ALL 3
79
80 size_t
81 strftime(char * const s, const size_t maxsize, const char * const format,
82 const struct tm * const t)
83 {
84 char * p;
85 int warn;
86
87 tzset();
88 warn = IN_NONE;
89 p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn);
90 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
91 if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
92 fprintf(stderr, "\n");
93 if (format == NULL)
94 fprintf(stderr, "NULL strftime format ");
95 else fprintf(stderr, "strftime format \"%s\" ",
96 format);
97 fprintf(stderr, "yields only two digits of years in ");
98 if (warn == IN_SOME)
99 fprintf(stderr, "some locales");
100 else if (warn == IN_THIS)
101 fprintf(stderr, "the current locale");
102 else fprintf(stderr, "all locales");
103 fprintf(stderr, "\n");
104 }
105 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
106 if (p == s + maxsize)
107 return 0;
108 *p = '\0';
109 return p - s;
110 }
111
112 static char *
113 _fmt(const char *format, const struct tm * const t, char *pt,
114 const char * const ptlim, int * warnp)
115 {
116 for ( ; *format; ++format) {
117 if (*format == '%') {
118 label:
119 switch (*++format) {
120 case '\0':
121 --format;
122 break;
123 case 'A':
124 pt = _add((t->tm_wday < 0 ||
125 t->tm_wday >= DAYSPERWEEK) ?
126 "?" : Locale->day[t->tm_wday],
127 pt, ptlim);
128 continue;
129 case 'a':
130 pt = _add((t->tm_wday < 0 ||
131 t->tm_wday >= DAYSPERWEEK) ?
132 "?" : Locale->abday[t->tm_wday],
133 pt, ptlim);
134 continue;
135 case 'B':
136 pt = _add((t->tm_mon < 0 ||
137 t->tm_mon >= MONSPERYEAR) ?
138 "?" : Locale->mon[t->tm_mon],
139 pt, ptlim);
140 continue;
141 case 'b':
142 case 'h':
143 pt = _add((t->tm_mon < 0 ||
144 t->tm_mon >= MONSPERYEAR) ?
145 "?" : Locale->abmon[t->tm_mon],
146 pt, ptlim);
147 continue;
148 case 'C':
149 /*
150 ** %C used to do a...
151 ** _fmt("%a %b %e %X %Y", t);
152 ** ...whereas now POSIX 1003.2 calls for
153 ** something completely different.
154 ** (ado, 1993-05-24)
155 */
156 pt = _conv((t->tm_year + TM_YEAR_BASE) / 100,
157 "%02d", pt, ptlim);
158 continue;
159 case 'c':
160 {
161 int warn2 = IN_SOME;
162
163 pt = _fmt(Locale->d_t_fmt, t, pt, ptlim, warnp);
164 if (warn2 == IN_ALL)
165 warn2 = IN_THIS;
166 if (warn2 > *warnp)
167 *warnp = warn2;
168 }
169 continue;
170 case 'D':
171 pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
172 continue;
173 case 'd':
174 pt = _conv(t->tm_mday, "%02d", pt, ptlim);
175 continue;
176 case 'E':
177 case 'O':
178 /*
179 ** C99 locale modifiers.
180 ** The sequences
181 ** %Ec %EC %Ex %EX %Ey %EY
182 ** %Od %oe %OH %OI %Om %OM
183 ** %OS %Ou %OU %OV %Ow %OW %Oy
184 ** are supposed to provide alternate
185 ** representations.
186 */
187 goto label;
188 case 'e':
189 pt = _conv(t->tm_mday, "%2d", pt, ptlim);
190 continue;
191 case 'F':
192 pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
193 continue;
194 case 'H':
195 pt = _conv(t->tm_hour, "%02d", pt, ptlim);
196 continue;
197 case 'I':
198 pt = _conv((t->tm_hour % 12) ?
199 (t->tm_hour % 12) : 12,
200 "%02d", pt, ptlim);
201 continue;
202 case 'j':
203 pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
204 continue;
205 case 'k':
206 /*
207 ** This used to be...
208 ** _conv(t->tm_hour % 12 ?
209 ** t->tm_hour % 12 : 12, 2, ' ');
210 ** ...and has been changed to the below to
211 ** match SunOS 4.1.1 and Arnold Robbins'
212 ** strftime version 3.0. That is, "%k" and
213 ** "%l" have been swapped.
214 ** (ado, 1993-05-24)
215 */
216 pt = _conv(t->tm_hour, "%2d", pt, ptlim);
217 continue;
218 #ifdef KITCHEN_SINK
219 case 'K':
220 /*
221 ** After all this time, still unclaimed!
222 */
223 pt = _add("kitchen sink", pt, ptlim);
224 continue;
225 #endif /* defined KITCHEN_SINK */
226 case 'l':
227 /*
228 ** This used to be...
229 ** _conv(t->tm_hour, 2, ' ');
230 ** ...and has been changed to the below to
231 ** match SunOS 4.1.1 and Arnold Robbin's
232 ** strftime version 3.0. That is, "%k" and
233 ** "%l" have been swapped.
234 ** (ado, 1993-05-24)
235 */
236 pt = _conv((t->tm_hour % 12) ?
237 (t->tm_hour % 12) : 12,
238 "%2d", pt, ptlim);
239 continue;
240 case 'M':
241 pt = _conv(t->tm_min, "%02d", pt, ptlim);
242 continue;
243 case 'm':
244 pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
245 continue;
246 case 'n':
247 pt = _add("\n", pt, ptlim);
248 continue;
249 case 'p':
250 pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
251 Locale->am_pm[1] :
252 Locale->am_pm[0],
253 pt, ptlim);
254 continue;
255 case 'R':
256 pt = _fmt("%H:%M", t, pt, ptlim, warnp);
257 continue;
258 case 'r':
259 pt = _fmt("%I:%M:%S %p", t, pt, ptlim, warnp);
260 continue;
261 case 'S':
262 pt = _conv(t->tm_sec, "%02d", pt, ptlim);
263 continue;
264 case 's':
265 {
266 struct tm tm;
267 char buf[INT_STRLEN_MAXIMUM(
268 time_t) + 1];
269 time_t mkt;
270
271 tm = *t;
272 mkt = mktime(&tm);
273 /* CONSTCOND */
274 if (TYPE_SIGNED(time_t))
275 sprintf(buf, "%ld",
276 (long) mkt);
277 else sprintf(buf, "%lu",
278 (unsigned long) mkt);
279 pt = _add(buf, pt, ptlim);
280 }
281 continue;
282 case 'T':
283 pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
284 continue;
285 case 't':
286 pt = _add("\t", pt, ptlim);
287 continue;
288 case 'U':
289 pt = _conv((t->tm_yday + DAYSPERWEEK -
290 t->tm_wday) / DAYSPERWEEK,
291 "%02d", pt, ptlim);
292 continue;
293 case 'u':
294 /*
295 ** From Arnold Robbins' strftime version 3.0:
296 ** "ISO 8601: Weekday as a decimal number
297 ** [1 (Monday) - 7]"
298 ** (ado, 1993-05-24)
299 */
300 pt = _conv((t->tm_wday == 0) ?
301 DAYSPERWEEK : t->tm_wday,
302 "%d", pt, ptlim);
303 continue;
304 case 'V': /* ISO 8601 week number */
305 case 'G': /* ISO 8601 year (four digits) */
306 case 'g': /* ISO 8601 year (two digits) */
307 /*
308 ** From Arnold Robbins' strftime version 3.0: "the week number of the
309 ** year (the first Monday as the first day of week 1) as a decimal number
310 ** (01-53)."
311 ** (ado, 1993-05-24)
312 **
313 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
314 ** "Week 01 of a year is per definition the first week which has the
315 ** Thursday in this year, which is equivalent to the week which contains
316 ** the fourth day of January. In other words, the first week of a new year
317 ** is the week which has the majority of its days in the new year. Week 01
318 ** might also contain days from the previous year and the week before week
319 ** 01 of a year is the last week (52 or 53) of the previous year even if
320 ** it contains days from the new year. A week starts with Monday (day 1)
321 ** and ends with Sunday (day 7). For example, the first week of the year
322 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
323 ** (ado, 1996-01-02)
324 */
325 {
326 int year;
327 int yday;
328 int wday;
329 int w;
330
331 year = t->tm_year + TM_YEAR_BASE;
332 yday = t->tm_yday;
333 wday = t->tm_wday;
334 for ( ; ; ) {
335 int len;
336 int bot;
337 int top;
338
339 len = isleap(year) ?
340 DAYSPERLYEAR :
341 DAYSPERNYEAR;
342 /*
343 ** What yday (-3 ... 3) does
344 ** the ISO year begin on?
345 */
346 bot = ((yday + 11 - wday) %
347 DAYSPERWEEK) - 3;
348 /*
349 ** What yday does the NEXT
350 ** ISO year begin on?
351 */
352 top = bot -
353 (len % DAYSPERWEEK);
354 if (top < -3)
355 top += DAYSPERWEEK;
356 top += len;
357 if (yday >= top) {
358 ++year;
359 w = 1;
360 break;
361 }
362 if (yday >= bot) {
363 w = 1 + ((yday - bot) /
364 DAYSPERWEEK);
365 break;
366 }
367 --year;
368 yday += isleap(year) ?
369 DAYSPERLYEAR :
370 DAYSPERNYEAR;
371 }
372 #ifdef XPG4_1994_04_09
373 if ((w == 52
374 && t->tm_mon == TM_JANUARY)
375 || (w == 1
376 && t->tm_mon == TM_DECEMBER))
377 w = 53;
378 #endif /* defined XPG4_1994_04_09 */
379 if (*format == 'V')
380 pt = _conv(w, "%02d",
381 pt, ptlim);
382 else if (*format == 'g') {
383 *warnp = IN_ALL;
384 pt = _conv(year % 100, "%02d",
385 pt, ptlim);
386 } else pt = _conv(year, "%04d",
387 pt, ptlim);
388 }
389 continue;
390 case 'v':
391 /*
392 ** From Arnold Robbins' strftime version 3.0:
393 ** "date as dd-bbb-YYYY"
394 ** (ado, 1993-05-24)
395 */
396 pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
397 continue;
398 case 'W':
399 pt = _conv((t->tm_yday + DAYSPERWEEK -
400 (t->tm_wday ?
401 (t->tm_wday - 1) :
402 (DAYSPERWEEK - 1))) / DAYSPERWEEK,
403 "%02d", pt, ptlim);
404 continue;
405 case 'w':
406 pt = _conv(t->tm_wday, "%d", pt, ptlim);
407 continue;
408 case 'X':
409 pt = _fmt(Locale->t_fmt, t, pt, ptlim, warnp);
410 continue;
411 case 'x':
412 {
413 int warn2 = IN_SOME;
414
415 pt = _fmt(Locale->d_fmt, t, pt, ptlim, &warn2);
416 if (warn2 == IN_ALL)
417 warn2 = IN_THIS;
418 if (warn2 > *warnp)
419 *warnp = warn2;
420 }
421 continue;
422 case 'y':
423 *warnp = IN_ALL;
424 pt = _conv((t->tm_year + TM_YEAR_BASE) % 100,
425 "%02d", pt, ptlim);
426 continue;
427 case 'Y':
428 pt = _conv(t->tm_year + TM_YEAR_BASE, "%04d",
429 pt, ptlim);
430 continue;
431 case 'Z':
432 #ifdef TM_ZONE
433 if (t->TM_ZONE != NULL)
434 pt = _add(t->TM_ZONE, pt, ptlim);
435 else
436 #endif /* defined TM_ZONE */
437 if (t->tm_isdst >= 0)
438 pt = _add(tzname[t->tm_isdst != 0],
439 pt, ptlim);
440 /*
441 ** C99 says that %Z must be replaced by the
442 ** empty string if the time zone is not
443 ** determinable.
444 */
445 continue;
446 case 'z':
447 {
448 int diff;
449 char const * sign;
450
451 if (t->tm_isdst < 0)
452 continue;
453 #ifdef TM_GMTOFF
454 diff = (int)t->TM_GMTOFF;
455 #else /* !defined TM_GMTOFF */
456 /*
457 ** C99 says that the UTC offset must
458 ** be computed by looking only at
459 ** tm_isdst. This requirement is
460 ** incorrect, since it means the code
461 ** must rely on magic (in this case
462 ** altzone and timezone), and the
463 ** magic might not have the correct
464 ** offset. Doing things correctly is
465 ** tricky and requires disobeying C99;
466 ** see GNU C strftime for details.
467 ** For now, punt and conform to the
468 ** standard, even though it's incorrect.
469 **
470 ** C99 says that %z must be replaced by the
471 ** empty string if the time zone is not
472 ** determinable, so output nothing if the
473 ** appropriate variables are not available.
474 */
475 #ifndef STD_INSPIRED
476 if (t->tm_isdst == 0)
477 #ifdef USG_COMPAT
478 diff = -timezone;
479 #else /* !defined USG_COMPAT */
480 continue;
481 #endif /* !defined USG_COMPAT */
482 else
483 #ifdef ALTZONE
484 diff = -altzone;
485 #else /* !defined ALTZONE */
486 continue;
487 #endif /* !defined ALTZONE */
488 #else /* defined STD_INSPIRED */
489 {
490 struct tm tmp;
491 time_t lct, gct;
492
493 /*
494 ** Get calendar time from t
495 ** being treated as local.
496 */
497 tmp = *t; /* mktime discards const */
498 lct = mktime(&tmp);
499
500 if (lct == (time_t)-1)
501 continue;
502
503 /*
504 ** Get calendar time from t
505 ** being treated as GMT.
506 **/
507 tmp = *t; /* mktime discards const */
508 gct = timegm(&tmp);
509
510 if (gct == (time_t)-1)
511 continue;
512
513 /* LINTED difference will fit int */
514 diff = (intmax_t)gct - (intmax_t)lct;
515 }
516 #endif /* defined STD_INSPIRED */
517 #endif /* !defined TM_GMTOFF */
518 if (diff < 0) {
519 sign = "-";
520 diff = -diff;
521 } else sign = "+";
522 pt = _add(sign, pt, ptlim);
523 diff /= 60;
524 pt = _conv((diff/60)*100 + diff%60,
525 "%04d", pt, ptlim);
526 }
527 continue;
528 case '+':
529 pt = _fmt(Locale->d_t_fmt, t, pt, ptlim,
530 warnp);
531 continue;
532 case '%':
533 /*
534 ** X311J/88-090 (4.12.3.5): if conversion char is
535 ** undefined, behavior is undefined. Print out the
536 ** character itself as printf(3) also does.
537 */
538 default:
539 break;
540 }
541 }
542 if (pt == ptlim)
543 break;
544 *pt++ = *format;
545 }
546 return pt;
547 }
548
549 static char *
550 _conv(const int n, const char * const format, char * const pt,
551 const char * const ptlim)
552 {
553 char buf[INT_STRLEN_MAXIMUM(int) + 1];
554
555 sprintf(buf, format, n);
556 return _add(buf, pt, ptlim);
557 }
558
559 static char *
560 _add(const char *str, char *pt, const char * const ptlim)
561 {
562 while (pt < ptlim && (*pt = *str++) != '\0')
563 ++pt;
564 return pt;
565 }
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