xref: /openbsd-src/lib/libc/time/strftime.c (revision 62a742911104f98b9185b2c6b6007d9b1c36396c)
1 #if defined(LIBC_SCCS) && !defined(lint) && !defined(NOID)
2 static char elsieid[] = "@(#)strftime.c	7.57";
3 static char *rcsid = "$OpenBSD: strftime.c,v 1.5 1998/08/14 21:39:44 deraadt Exp $";
4 #endif /* LIBC_SCCS and not lint */
5 
6 #include "private.h"
7 
8 /*
9 ** Based on the UCB version with the ID appearing below.
10 ** This is ANSIish only when "multibyte character == plain character".
11 **
12 ** Copyright (c) 1989 The Regents of the University of California.
13 ** All rights reserved.
14 **
15 ** Redistribution and use in source and binary forms are permitted
16 ** provided that the above copyright notice and this paragraph are
17 ** duplicated in all such forms and that any documentation,
18 ** advertising materials, and other materials related to such
19 ** distribution and use acknowledge that the software was developed
20 ** by the University of California, Berkeley.  The name of the
21 ** University may not be used to endorse or promote products derived
22 ** from this software without specific prior written permission.
23 ** THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
24 ** IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
25 ** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
26 */
27 
28 #if 0
29 #ifndef LIBC_SCCS
30 #ifndef lint
31 static const char	sccsid[] = "@(#)strftime.c	5.4 (Berkeley) 3/14/89";
32 #endif /* !defined lint */
33 #endif /* !defined LIBC_SCCS */
34 #endif
35 
36 #include "tzfile.h"
37 #include "fcntl.h"
38 #include "locale.h"
39 
40 struct lc_time_T {
41 	const char *	mon[MONSPERYEAR];
42 	const char *	month[MONSPERYEAR];
43 	const char *	wday[DAYSPERWEEK];
44 	const char *	weekday[DAYSPERWEEK];
45 	const char *	X_fmt;
46 	const char *	x_fmt;
47 	const char *	c_fmt;
48 	const char *	am;
49 	const char *	pm;
50 	const char *	date_fmt;
51 };
52 
53 #ifdef LOCALE_HOME
54 #include "sys/stat.h"
55 static struct lc_time_T		localebuf;
56 static struct lc_time_T *	_loc P((void));
57 #define Locale	_loc()
58 #endif /* defined LOCALE_HOME */
59 #ifndef LOCALE_HOME
60 #define Locale	(&C_time_locale)
61 #endif /* !defined LOCALE_HOME */
62 
63 static const struct lc_time_T	C_time_locale = {
64 	{
65 		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
66 		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
67 	}, {
68 		"January", "February", "March", "April", "May", "June",
69 		"July", "August", "September", "October", "November", "December"
70 	}, {
71 		"Sun", "Mon", "Tue", "Wed",
72 		"Thu", "Fri", "Sat"
73 	}, {
74 		"Sunday", "Monday", "Tuesday", "Wednesday",
75 		"Thursday", "Friday", "Saturday"
76 	},
77 
78 	/* X_fmt */
79 	"%H:%M:%S",
80 
81 	/*
82 	** x_fmt
83 	** Since the C language standard calls for
84 	** "date, using locale's date format," anything goes.
85 	** Using just numbers (as here) makes Quakers happier;
86 	** it's also compatible with SVR4.
87 	**
88 	** XXX--might it be better to use the year-2000 friendly
89 	**	%Y-%m-%d
90 	** here?
91 	*/
92 	"%m/%d/%y",
93 
94 	/*
95 	** c_fmt
96 	** XXX--Changed by millert from "%D %X"
97 	**      to the more common "%a %b %d %H:%M:%S %Y"
98 	**      used by everyone else.
99 	*/
100 	"%a %b %d %H:%M:%S %Y",
101 
102 	/* am */
103 	"AM",
104 
105 	/* pm */
106 	"PM",
107 
108 	/* date_fmt */
109 	"%a %b %e %H:%M:%S %Z %Y"
110 };
111 
112 static char *	_add P((const char *, char *, const char *));
113 static char *	_conv P((int, const char *, char *, const char *));
114 static char *	_fmt P((const char *, const struct tm *, char *, const char *, int *));
115 
116 size_t strftime P((char *, size_t, const char *, const struct tm *));
117 
118 extern char *	tzname[];
119 
120 #ifndef YEAR_2000_NAME
121 #define YEAR_2000_NAME	"CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
122 #endif /* !defined YEAR_2000_NAME */
123 
124 
125 #define IN_NONE	0
126 #define IN_SOME	1
127 #define IN_THIS	2
128 #define IN_ALL	3
129 
130 size_t
131 strftime(s, maxsize, format, t)
132 char * const		s;
133 const size_t		maxsize;
134 const char * const	format;
135 const struct tm * const	t;
136 {
137 	char *	p;
138 	int	warn;
139 
140 	tzset();
141 #ifdef LOCALE_HOME
142 	localebuf.mon[0] = 0;
143 #endif /* defined LOCALE_HOME */
144 	warn = IN_NONE;
145 	p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn);
146 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
147 	if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
148 		(void) fprintf(stderr, "\n");
149 		if (format == NULL)
150 			(void) fprintf(stderr, "NULL strftime format ");
151 		else	(void) fprintf(stderr, "strftime format \"%s\" ",
152 				format);
153 		(void) fprintf(stderr, "yields only two digits of years in ");
154 		if (warn == IN_SOME)
155 			(void) fprintf(stderr, "some locales");
156 		else if (warn == IN_THIS)
157 			(void) fprintf(stderr, "the current locale");
158 		else	(void) fprintf(stderr, "all locales");
159 		(void) fprintf(stderr, "\n");
160 	}
161 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
162 	if (p == s + maxsize) {
163 		if (maxsize > 0)
164 			s[maxsize - 1] = '\0';
165 		return 0;
166 	}
167 	*p = '\0';
168 	return p - s;
169 }
170 
171 static char *
172 _fmt(format, t, pt, ptlim, warnp)
173 const char *		format;
174 const struct tm * const	t;
175 char *			pt;
176 const char * const	ptlim;
177 int *			warnp;
178 {
179 	for ( ; *format; ++format) {
180 		if (*format == '%') {
181 label:
182 			switch (*++format) {
183 			case '\0':
184 				--format;
185 				break;
186 			case 'A':
187 				pt = _add((t->tm_wday < 0 ||
188 					t->tm_wday >= DAYSPERWEEK) ?
189 					"?" : Locale->weekday[t->tm_wday],
190 					pt, ptlim);
191 				continue;
192 			case 'a':
193 				pt = _add((t->tm_wday < 0 ||
194 					t->tm_wday >= DAYSPERWEEK) ?
195 					"?" : Locale->wday[t->tm_wday],
196 					pt, ptlim);
197 				continue;
198 			case 'B':
199 				pt = _add((t->tm_mon < 0 ||
200 					t->tm_mon >= MONSPERYEAR) ?
201 					"?" : Locale->month[t->tm_mon],
202 					pt, ptlim);
203 				continue;
204 			case 'b':
205 			case 'h':
206 				pt = _add((t->tm_mon < 0 ||
207 					t->tm_mon >= MONSPERYEAR) ?
208 					"?" : Locale->mon[t->tm_mon],
209 					pt, ptlim);
210 				continue;
211 			case 'C':
212 				/*
213 				** %C used to do a...
214 				**	_fmt("%a %b %e %X %Y", t);
215 				** ...whereas now POSIX 1003.2 calls for
216 				** something completely different.
217 				** (ado, 1993-05-24)
218 				*/
219 				pt = _conv((t->tm_year + TM_YEAR_BASE) / 100,
220 					"%02d", pt, ptlim);
221 				continue;
222 			case 'c':
223 				{
224 				int warn2 = IN_SOME;
225 
226 				pt = _fmt(Locale->c_fmt, t, pt, ptlim, warnp);
227 				if (warn2 == IN_ALL)
228 					warn2 = IN_THIS;
229 				if (warn2 > *warnp)
230 					*warnp = warn2;
231 				}
232 				continue;
233 			case 'D':
234 				pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
235 				continue;
236 			case 'd':
237 				pt = _conv(t->tm_mday, "%02d", pt, ptlim);
238 				continue;
239 			case 'E':
240 			case 'O':
241 				/*
242 				** POSIX locale extensions, a la
243 				** Arnold Robbins' strftime version 3.0.
244 				** The sequences
245 				**	%Ec %EC %Ex %Ey %EY
246 				**	%Od %oe %OH %OI %Om %OM
247 				**	%OS %Ou %OU %OV %Ow %OW %Oy
248 				** are supposed to provide alternate
249 				** representations.
250 				** (ado, 1993-05-24)
251 				*/
252 				goto label;
253 			case 'e':
254 				pt = _conv(t->tm_mday, "%2d", pt, ptlim);
255 				continue;
256 			case 'H':
257 				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
258 				continue;
259 			case 'I':
260 				pt = _conv((t->tm_hour % 12) ?
261 					(t->tm_hour % 12) : 12,
262 					"%02d", pt, ptlim);
263 				continue;
264 			case 'j':
265 				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
266 				continue;
267 			case 'k':
268 				/*
269 				** This used to be...
270 				**	_conv(t->tm_hour % 12 ?
271 				**		t->tm_hour % 12 : 12, 2, ' ');
272 				** ...and has been changed to the below to
273 				** match SunOS 4.1.1 and Arnold Robbins'
274 				** strftime version 3.0.  That is, "%k" and
275 				** "%l" have been swapped.
276 				** (ado, 1993-05-24)
277 				*/
278 				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
279 				continue;
280 #ifdef KITCHEN_SINK
281 			case 'K':
282 				/*
283 				** After all this time, still unclaimed!
284 				*/
285 				pt = _add("kitchen sink", pt, ptlim);
286 				continue;
287 #endif /* defined KITCHEN_SINK */
288 			case 'l':
289 				/*
290 				** This used to be...
291 				**	_conv(t->tm_hour, 2, ' ');
292 				** ...and has been changed to the below to
293 				** match SunOS 4.1.1 and Arnold Robbin's
294 				** strftime version 3.0.  That is, "%k" and
295 				** "%l" have been swapped.
296 				** (ado, 1993-05-24)
297 				*/
298 				pt = _conv((t->tm_hour % 12) ?
299 					(t->tm_hour % 12) : 12,
300 					"%2d", pt, ptlim);
301 				continue;
302 			case 'M':
303 				pt = _conv(t->tm_min, "%02d", pt, ptlim);
304 				continue;
305 			case 'm':
306 				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
307 				continue;
308 			case 'n':
309 				pt = _add("\n", pt, ptlim);
310 				continue;
311 			case 'p':
312 				pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
313 					Locale->pm :
314 					Locale->am,
315 					pt, ptlim);
316 				continue;
317 			case 'R':
318 				pt = _fmt("%H:%M", t, pt, ptlim, warnp);
319 				continue;
320 			case 'r':
321 				pt = _fmt("%I:%M:%S %p", t, pt, ptlim, warnp);
322 				continue;
323 			case 'S':
324 				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
325 				continue;
326 			case 's':
327 				{
328 					struct tm	tm;
329 					char		buf[INT_STRLEN_MAXIMUM(
330 								time_t) + 1];
331 					time_t		mkt;
332 
333 					tm = *t;
334 					mkt = mktime(&tm);
335 					if (TYPE_SIGNED(time_t))
336 						(void) sprintf(buf, "%ld",
337 							(long) mkt);
338 					else	(void) sprintf(buf, "%lu",
339 							(unsigned long) mkt);
340 					pt = _add(buf, pt, ptlim);
341 				}
342 				continue;
343 			case 'T':
344 				pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
345 				continue;
346 			case 't':
347 				pt = _add("\t", pt, ptlim);
348 				continue;
349 			case 'U':
350 				pt = _conv((t->tm_yday + DAYSPERWEEK -
351 					t->tm_wday) / DAYSPERWEEK,
352 					"%02d", pt, ptlim);
353 				continue;
354 			case 'u':
355 				/*
356 				** From Arnold Robbins' strftime version 3.0:
357 				** "ISO 8601: Weekday as a decimal number
358 				** [1 (Monday) - 7]"
359 				** (ado, 1993-05-24)
360 				*/
361 				pt = _conv((t->tm_wday == 0) ?
362 					DAYSPERWEEK : t->tm_wday,
363 					"%d", pt, ptlim);
364 				continue;
365 			case 'V':	/* ISO 8601 week number */
366 			case 'G':	/* ISO 8601 year (four digits) */
367 			case 'g':	/* ISO 8601 year (two digits) */
368 /*
369 ** From Arnold Robbins' strftime version 3.0:  "the week number of the
370 ** year (the first Monday as the first day of week 1) as a decimal number
371 ** (01-53)."
372 ** (ado, 1993-05-24)
373 **
374 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
375 ** "Week 01 of a year is per definition the first week which has the
376 ** Thursday in this year, which is equivalent to the week which contains
377 ** the fourth day of January. In other words, the first week of a new year
378 ** is the week which has the majority of its days in the new year. Week 01
379 ** might also contain days from the previous year and the week before week
380 ** 01 of a year is the last week (52 or 53) of the previous year even if
381 ** it contains days from the new year. A week starts with Monday (day 1)
382 ** and ends with Sunday (day 7).  For example, the first week of the year
383 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
384 ** (ado, 1996-01-02)
385 */
386 				{
387 					int	year;
388 					int	yday;
389 					int	wday;
390 					int	w;
391 
392 					year = t->tm_year + TM_YEAR_BASE;
393 					yday = t->tm_yday;
394 					wday = t->tm_wday;
395 					for ( ; ; ) {
396 						int	len;
397 						int	bot;
398 						int	top;
399 
400 						len = isleap(year) ?
401 							DAYSPERLYEAR :
402 							DAYSPERNYEAR;
403 						/*
404 						** What yday (-3 ... 3) does
405 						** the ISO year begin on?
406 						*/
407 						bot = ((yday + 11 - wday) %
408 							DAYSPERWEEK) - 3;
409 						/*
410 						** What yday does the NEXT
411 						** ISO year begin on?
412 						*/
413 						top = bot -
414 							(len % DAYSPERWEEK);
415 						if (top < -3)
416 							top += DAYSPERWEEK;
417 						top += len;
418 						if (yday >= top) {
419 							++year;
420 							w = 1;
421 							break;
422 						}
423 						if (yday >= bot) {
424 							w = 1 + ((yday - bot) /
425 								DAYSPERWEEK);
426 							break;
427 						}
428 						--year;
429 						yday += isleap(year) ?
430 							DAYSPERLYEAR :
431 							DAYSPERNYEAR;
432 					}
433 #ifdef XPG4_1994_04_09
434 					if ((w == 52
435 					     && t->tm_mon == TM_JANUARY)
436 					    || (w == 1
437 						&& t->tm_mon == TM_DECEMBER))
438 						w = 53;
439 #endif /* defined XPG4_1994_04_09 */
440 					if (*format == 'V')
441 						pt = _conv(w, "%02d",
442 							pt, ptlim);
443 					else if (*format == 'g') {
444 						*warnp = IN_ALL;
445 						pt = _conv(year % 100, "%02d",
446 							pt, ptlim);
447 					} else	pt = _conv(year, "%04d",
448 							pt, ptlim);
449 				}
450 				continue;
451 			case 'v':
452 				/*
453 				** From Arnold Robbins' strftime version 3.0:
454 				** "date as dd-bbb-YYYY"
455 				** (ado, 1993-05-24)
456 				*/
457 				pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
458 				continue;
459 			case 'W':
460 				pt = _conv((t->tm_yday + DAYSPERWEEK -
461 					(t->tm_wday ?
462 					(t->tm_wday - 1) :
463 					(DAYSPERWEEK - 1))) / DAYSPERWEEK,
464 					"%02d", pt, ptlim);
465 				continue;
466 			case 'w':
467 				pt = _conv(t->tm_wday, "%d", pt, ptlim);
468 				continue;
469 			case 'X':
470 				pt = _fmt(Locale->X_fmt, t, pt, ptlim, warnp);
471 				continue;
472 			case 'x':
473 				{
474 				int	warn2 = IN_SOME;
475 
476 				pt = _fmt(Locale->x_fmt, t, pt, ptlim, &warn2);
477 				if (warn2 == IN_ALL)
478 					warn2 = IN_THIS;
479 				if (warn2 > *warnp)
480 					*warnp = warn2;
481 				}
482 				continue;
483 			case 'y':
484 				*warnp = IN_ALL;
485 				pt = _conv((t->tm_year + TM_YEAR_BASE) % 100,
486 					"%02d", pt, ptlim);
487 				continue;
488 			case 'Y':
489 				pt = _conv(t->tm_year + TM_YEAR_BASE, "%04d",
490 					pt, ptlim);
491 				continue;
492 			case 'Z':
493 #ifdef TM_ZONE
494 				if (t->TM_ZONE != NULL)
495 					pt = _add(t->TM_ZONE, pt, ptlim);
496 				else
497 #endif /* defined TM_ZONE */
498 				if (t->tm_isdst == 0 || t->tm_isdst == 1) {
499 					pt = _add(tzname[t->tm_isdst],
500 						pt, ptlim);
501 				} else  pt = _add("?", pt, ptlim);
502 				continue;
503 			case '+':
504 				pt = _fmt(Locale->date_fmt, t, pt, ptlim,
505 					warnp);
506 				continue;
507 			case '%':
508 			/*
509 			 * X311J/88-090 (4.12.3.5): if conversion char is
510 			 * undefined, behavior is undefined.  Print out the
511 			 * character itself as printf(3) also does.
512 			 */
513 			default:
514 				break;
515 			}
516 		}
517 		if (pt == ptlim)
518 			break;
519 		*pt++ = *format;
520 	}
521 	return pt;
522 }
523 
524 static char *
525 _conv(n, format, pt, ptlim)
526 const int		n;
527 const char * const	format;
528 char * const		pt;
529 const char * const	ptlim;
530 {
531 	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
532 
533 	(void) sprintf(buf, format, n);
534 	return _add(buf, pt, ptlim);
535 }
536 
537 static char *
538 _add(str, pt, ptlim)
539 const char *		str;
540 char *			pt;
541 const char * const	ptlim;
542 {
543 	while (pt < ptlim && (*pt = *str++) != '\0')
544 		++pt;
545 	return pt;
546 }
547 
548 #ifdef LOCALE_HOME
549 static struct lc_time_T *
550 _loc P((void))
551 {
552 	static const char	locale_home[] = LOCALE_HOME;
553 	static const char	lc_time[] = "LC_TIME";
554 	static char *		locale_buf;
555 	static char		locale_buf_C[] = "C";
556 
557 	int			fd;
558 	int			oldsun;	/* "...ain't got nothin' to do..." */
559 	char *			lbuf;
560 	char *			nlbuf;
561 	char *			name;
562 	char *			p;
563 	const char **		ap;
564 	const char *		plim;
565 	char			filename[FILENAME_MAX];
566 	struct stat		st;
567 	size_t			namesize;
568 	size_t			bufsize;
569 
570 	/*
571 	** Use localebuf.mon[0] to signal whether locale is already set up.
572 	*/
573 	if (localebuf.mon[0])
574 		return &localebuf;
575 	name = setlocale(LC_TIME, (char *) NULL);
576 	if (name == NULL || *name == '\0')
577 		goto no_locale;
578 	/*
579 	** If the locale name is the same as our cache, use the cache.
580 	*/
581 	lbuf = locale_buf;
582 	if (lbuf != NULL && strcmp(name, lbuf) == 0) {
583 		p = lbuf;
584 		for (ap = (const char **) &localebuf;
585 			ap < (const char **) (&localebuf + 1);
586 				++ap)
587 					*ap = p += strlen(p) + 1;
588 		return &localebuf;
589 	}
590 	/*
591 	** Slurp the locale file into the cache.
592 	*/
593 	namesize = strlen(name) + 1;
594 	if (sizeof(filename) <
595 		sizeof(locale_home) + namesize + sizeof(lc_time))
596 			goto no_locale;
597 	oldsun = 0;
598 	(void) sprintf(filename, "%s/%s/%s", locale_home, name, lc_time);
599 	fd = open(filename, O_RDONLY);
600 	if (fd < 0) {
601 		/*
602 		** Old Sun systems have a different naming and data convention.
603 		*/
604 		oldsun = 1;
605 		(void) sprintf(filename, "%s/%s/%s", locale_home,
606 			lc_time, name);
607 		fd = open(filename, O_RDONLY);
608 		if (fd < 0)
609 			goto no_locale;
610 	}
611 	if (fstat(fd, &st) != 0)
612 		goto bad_locale;
613 	if (st.st_size <= 0)
614 		goto bad_locale;
615 	bufsize = namesize + st.st_size;
616 	locale_buf = NULL;
617 	nlbuf = (lbuf == NULL || lbuf == locale_buf_C) ?
618 		malloc(bufsize) : realloc(lbuf, bufsize);
619 	if (nlbuf == NULL) {
620 		if (lbuf)
621 			free(lbuf);
622 		lbuf = NULL;
623 		goto bad_locale;
624 	}
625 	lbuf = nlbuf;
626 	(void) strcpy(lbuf, name);
627 	p = lbuf + namesize;
628 	plim = p + st.st_size;
629 	if (read(fd, p, (size_t) st.st_size) != st.st_size)
630 		goto bad_lbuf;
631 	if (close(fd) != 0)
632 		goto bad_lbuf;
633 	/*
634 	** Parse the locale file into localebuf.
635 	*/
636 	if (plim[-1] != '\n')
637 		goto bad_lbuf;
638 	for (ap = (const char **) &localebuf;
639 		ap < (const char **) (&localebuf + 1);
640 			++ap) {
641 				if (p == plim)
642 					goto bad_lbuf;
643 				*ap = p;
644 				while (*p != '\n')
645 					++p;
646 				*p++ = '\0';
647 	}
648 	if (oldsun) {
649 		/*
650 		** SunOS 4 used an obsolescent format; see localdtconv(3).
651 		** c_fmt had the ``short format for dates and times together''
652 		** (SunOS 4 date, "%a %b %e %T %Z %Y" in the C locale);
653 		** date_fmt had the ``long format for dates''
654 		** (SunOS 4 strftime %C, "%A, %B %e, %Y" in the C locale).
655 		** Discard the latter in favor of the former.
656 		*/
657 		localebuf.date_fmt = localebuf.c_fmt;
658 	}
659 	/*
660 	** Record the successful parse in the cache.
661 	*/
662 	locale_buf = lbuf;
663 
664 	return &localebuf;
665 
666 bad_lbuf:
667 	free(lbuf);
668 bad_locale:
669 	(void) close(fd);
670 no_locale:
671 	localebuf = C_time_locale;
672 	locale_buf = locale_buf_C;
673 	return &localebuf;
674 }
675 #endif /* defined LOCALE_HOME */
676