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[dragonfly.git] / lib / libc / stdtime / strftime.c
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 1.5 2005/04/21 16:36:35 joerg 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                 (void) fprintf(stderr, "\n");
93                 if (format == NULL)
94                         (void) fprintf(stderr, "NULL strftime format ");
95                 else    (void) fprintf(stderr, "strftime format \"%s\" ",
96                                 format);
97                 (void) fprintf(stderr, "yields only two digits of years in ");
98                 if (warn == IN_SOME)
99                         (void) fprintf(stderr, "some locales");
100                 else if (warn == IN_THIS)
101                         (void) fprintf(stderr, "the current locale");
102                 else    (void) fprintf(stderr, "all locales");
103                 (void) 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                                                 (void) sprintf(buf, "%ld",
276                                                         (long) mkt);
277                                         else    (void) 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         (void) 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 }