xref: /freebsd-src/lib/libc/stdtime/strftime.c (revision faeb1b822a2ec18e5d4e6e47e46264210fbab0f3)
1 /*
2  * Copyright (c) 1989 The Regents of the University of California.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms are permitted
6  * provided that the above copyright notice and this paragraph are
7  * duplicated in all such forms and that any documentation,
8  * advertising materials, and other materials related to such
9  * distribution and use acknowledge that the software was developed
10  * by the University of California, Berkeley.  The name of the
11  * University may not be used to endorse or promote products derived
12  * from this software without specific prior written permission.
13  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
14  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
16  */
17 
18 #ifdef LIBC_RCS
19 static const char rcsid[] =
20   "$FreeBSD$";
21 #endif
22 
23 #ifndef lint
24 #ifndef NOID
25 static const char	elsieid[] = "@(#)strftime.c	7.38";
26 /*
27 ** Based on the UCB version with the ID appearing below.
28 ** This is ANSIish only when "multibyte character == plain character".
29 */
30 #endif /* !defined NOID */
31 #endif /* !defined lint */
32 
33 #include "namespace.h"
34 #include "private.h"
35 
36 #ifndef LIBC_SCCS
37 #ifndef lint
38 static const char	sccsid[] = "@(#)strftime.c	5.4 (Berkeley) 3/14/89";
39 #endif /* !defined lint */
40 #endif /* !defined LIBC_SCCS */
41 
42 #include "tzfile.h"
43 #include <fcntl.h>
44 #include <sys/stat.h>
45 #include "un-namespace.h"
46 #include "timelocal.h"
47 
48 static char *	_add P((const char *, char *, const char *));
49 static char *	_conv P((int, const char *, char *, const char *));
50 static char *	_fmt P((const char *, const struct tm *, char *, const char *));
51 
52 size_t strftime P((char *, size_t, const char *, const struct tm *));
53 
54 extern char *	tzname[];
55 
56 size_t
57 strftime(s, maxsize, format, t)
58 	char *const s;
59 	const size_t maxsize;
60 	const char *const format;
61 	const struct tm *const t;
62 {
63 	char *p;
64 
65 	tzset();
66 	p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize);
67 	if (p == s + maxsize)
68 		return 0;
69 	*p = '\0';
70 	return p - s;
71 }
72 
73 static char *
74 _fmt(format, t, pt, ptlim)
75 	const char *format;
76 	const struct tm *const t;
77 	char *pt;
78 	const char *const ptlim;
79 {
80 	int Ealternative, Oalternative;
81 	struct lc_time_T *tptr = __get_current_time_locale();
82 
83 	for ( ; *format; ++format) {
84 		if (*format == '%') {
85 			Ealternative = 0;
86 			Oalternative = 0;
87 label:
88 			switch (*++format) {
89 			case '\0':
90 				--format;
91 				break;
92 			case 'A':
93 				pt = _add((t->tm_wday < 0 || t->tm_wday > 6) ?
94 					"?" : tptr->weekday[t->tm_wday],
95 					pt, ptlim);
96 				continue;
97 			case 'a':
98 				pt = _add((t->tm_wday < 0 || t->tm_wday > 6) ?
99 					"?" : tptr->wday[t->tm_wday],
100 					pt, ptlim);
101 				continue;
102 			case 'B':
103 				pt = _add((t->tm_mon < 0 || t->tm_mon > 11) ?
104 					"?" : (Oalternative ? tptr->alt_month :
105 					tptr->month)[t->tm_mon],
106 					pt, ptlim);
107 				continue;
108 			case 'b':
109 			case 'h':
110 				pt = _add((t->tm_mon < 0 || t->tm_mon > 11) ?
111 					"?" : tptr->mon[t->tm_mon],
112 					pt, ptlim);
113 				continue;
114 			case 'C':
115 				/*
116 				** %C used to do a...
117 				**	_fmt("%a %b %e %X %Y", t);
118 				** ...whereas now POSIX 1003.2 calls for
119 				** something completely different.
120 				** (ado, 5/24/93)
121 				*/
122 				pt = _conv((t->tm_year + TM_YEAR_BASE) / 100,
123 					"%02d", pt, ptlim);
124 				continue;
125 			case 'c':
126 				pt = _fmt(tptr->c_fmt, t, pt, ptlim);
127 				continue;
128 			case 'D':
129 				pt = _fmt("%m/%d/%y", t, pt, ptlim);
130 				continue;
131 			case 'd':
132 				pt = _conv(t->tm_mday, "%02d", pt, ptlim);
133 				continue;
134 			case 'E':
135 				if (Ealternative || Oalternative)
136 					break;
137 				Ealternative++;
138 				goto label;
139 			case 'O':
140 				/*
141 				** POSIX locale extensions, a la
142 				** Arnold Robbins' strftime version 3.0.
143 				** The sequences
144 				**      %Ec %EC %Ex %EX %Ey %EY
145 				**	%Od %oe %OH %OI %Om %OM
146 				**	%OS %Ou %OU %OV %Ow %OW %Oy
147 				** are supposed to provide alternate
148 				** representations.
149 				** (ado, 5/24/93)
150 				**
151 				** FreeBSD extensions
152 				**      %OB %Ef %EF
153 				*/
154 				if (Ealternative || Oalternative)
155 					break;
156 				Oalternative++;
157 				goto label;
158 			case 'e':
159 				pt = _conv(t->tm_mday, "%2d", pt, ptlim);
160 				continue;
161 			case 'f':
162 				if (!Ealternative)
163 					break;
164 				pt = _fmt(*(tptr->md_order) == 'd' ?
165 					  "%e %b" : "%b %e",
166 					  t, pt, ptlim);
167 				continue;
168 			case 'F':
169 				if (!Ealternative)
170 					pt = _fmt("%Y-%m-%d", t, pt, ptlim);
171 				else
172 					pt = _fmt(*(tptr->md_order) == 'd' ?
173 						  "%e %B" : "%B %e",
174 						  t, pt, ptlim);
175 				continue;
176 			case 'H':
177 				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
178 				continue;
179 			case 'I':
180 				pt = _conv((t->tm_hour % 12) ?
181 					(t->tm_hour % 12) : 12,
182 					"%02d", pt, ptlim);
183 				continue;
184 			case 'j':
185 				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
186 				continue;
187 			case 'k':
188 				/*
189 				** This used to be...
190 				**	_conv(t->tm_hour % 12 ?
191 				**		t->tm_hour % 12 : 12, 2, ' ');
192 				** ...and has been changed to the below to
193 				** match SunOS 4.1.1 and Arnold Robbins'
194 				** strftime version 3.0.  That is, "%k" and
195 				** "%l" have been swapped.
196 				** (ado, 5/24/93)
197 				*/
198 				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
199 				continue;
200 #ifdef KITCHEN_SINK
201 			case 'K':
202 				/*
203 				** After all this time, still unclaimed!
204 				*/
205 				pt = _add("kitchen sink", pt, ptlim);
206 				continue;
207 #endif /* defined KITCHEN_SINK */
208 			case 'l':
209 				/*
210 				** This used to be...
211 				**	_conv(t->tm_hour, 2, ' ');
212 				** ...and has been changed to the below to
213 				** match SunOS 4.1.1 and Arnold Robbin's
214 				** strftime version 3.0.  That is, "%k" and
215 				** "%l" have been swapped.
216 				** (ado, 5/24/93)
217 				*/
218 				pt = _conv((t->tm_hour % 12) ?
219 					(t->tm_hour % 12) : 12,
220 					"%2d", pt, ptlim);
221 				continue;
222 			case 'M':
223 				pt = _conv(t->tm_min, "%02d", pt, ptlim);
224 				continue;
225 			case 'm':
226 				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
227 				continue;
228 			case 'n':
229 				pt = _add("\n", pt, ptlim);
230 				continue;
231 			case 'p':
232 				pt = _add((t->tm_hour >= 12) ?
233 					tptr->pm :
234 					tptr->am,
235 					pt, ptlim);
236 				continue;
237 			case 'R':
238 				pt = _fmt("%H:%M", t, pt, ptlim);
239 				continue;
240 			case 'r':
241 				pt = _fmt(tptr->ampm_fmt, t, pt, ptlim);
242 				continue;
243 			case 'S':
244 				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
245 				continue;
246 			case 's':
247 				{
248 					struct tm	tm;
249 					char		buf[INT_STRLEN_MAXIMUM(
250 								time_t) + 1];
251 					time_t		mkt;
252 
253 					tm = *t;
254 					mkt = mktime(&tm);
255 					if (TYPE_SIGNED(time_t))
256 						(void) sprintf(buf, "%ld",
257 							(long) mkt);
258 					else	(void) sprintf(buf, "%lu",
259 							(unsigned long) mkt);
260 					pt = _add(buf, pt, ptlim);
261 				}
262 				continue;
263 			case 'T':
264 				pt = _fmt("%H:%M:%S", t, pt, ptlim);
265 				continue;
266 			case 't':
267 				pt = _add("\t", pt, ptlim);
268 				continue;
269 			case 'U':
270 				pt = _conv((t->tm_yday + 7 - t->tm_wday) / 7,
271 					"%02d", pt, ptlim);
272 				continue;
273 			case 'u':
274 				/*
275 				** From Arnold Robbins' strftime version 3.0:
276 				** "ISO 8601: Weekday as a decimal number
277 				** [1 (Monday) - 7]"
278 				** (ado, 5/24/93)
279 				*/
280 				pt = _conv((t->tm_wday == 0) ? 7 : t->tm_wday,
281 					"%d", pt, ptlim);
282 				continue;
283 			case 'V':	/* ISO 8601 week number */
284 			case 'G':	/* ISO 8601 year (four digits) */
285 			case 'g':	/* ISO 8601 year (two digits) */
286 /*
287 ** From Arnold Robbins' strftime version 3.0:  "the week number of the
288 ** year (the first Monday as the first day of week 1) as a decimal number
289 ** (01-53)."
290 ** (ado, 1993-05-24)
291 **
292 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
293 ** "Week 01 of a year is per definition the first week which has the
294 ** Thursday in this year, which is equivalent to the week which contains
295 ** the fourth day of January. In other words, the first week of a new year
296 ** is the week which has the majority of its days in the new year. Week 01
297 ** might also contain days from the previous year and the week before week
298 ** 01 of a year is the last week (52 or 53) of the previous year even if
299 ** it contains days from the new year. A week starts with Monday (day 1)
300 ** and ends with Sunday (day 7).  For example, the first week of the year
301 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
302 ** (ado, 1996-01-02)
303 */
304 				{
305 					int	year;
306 					int	yday;
307 					int	wday;
308 					int	w;
309 
310 					year = t->tm_year + TM_YEAR_BASE;
311 					yday = t->tm_yday;
312 					wday = t->tm_wday;
313 					for ( ; ; ) {
314 						int	len;
315 						int	bot;
316 						int	top;
317 
318 						len = isleap(year) ?
319 							DAYSPERLYEAR :
320 							DAYSPERNYEAR;
321 						/*
322 						** What yday (-3 ... 3) does
323 						** the ISO year begin on?
324 						*/
325 						bot = ((yday + 11 - wday) %
326 							DAYSPERWEEK) - 3;
327 						/*
328 						** What yday does the NEXT
329 						** ISO year begin on?
330 						*/
331 						top = bot -
332 							(len % DAYSPERWEEK);
333 						if (top < -3)
334 							top += DAYSPERWEEK;
335 						top += len;
336 						if (yday >= top) {
337 							++year;
338 							w = 1;
339 							break;
340 						}
341 						if (yday >= bot) {
342 							w = 1 + ((yday - bot) /
343 								DAYSPERWEEK);
344 							break;
345 						}
346 						--year;
347 						yday += isleap(year) ?
348 							DAYSPERLYEAR :
349 							DAYSPERNYEAR;
350 					}
351 #ifdef XPG4_1994_04_09
352 					if ((w == 52
353 					     && t->tm_mon == TM_JANUARY)
354 					    || (w == 1
355 						&& t->tm_mon == TM_DECEMBER))
356 						w = 53;
357 #endif /* defined XPG4_1994_04_09 */
358 					if (*format == 'V')
359 						pt = _conv(w, "%02d",
360 							pt, ptlim);
361 					else if (*format == 'g') {
362 						pt = _conv(year % 100, "%02d",
363 							pt, ptlim);
364 					} else	pt = _conv(year, "%04d",
365 							pt, ptlim);
366 				}
367 				continue;
368 			case 'v':
369 				/*
370 				** From Arnold Robbins' strftime version 3.0:
371 				** "date as dd-bbb-YYYY"
372 				** (ado, 5/24/93)
373 				*/
374 				pt = _fmt("%e-%b-%Y", t, pt, ptlim);
375 				continue;
376 			case 'W':
377 				pt = _conv((t->tm_yday + 7 -
378 					(t->tm_wday ?
379 					(t->tm_wday - 1) : 6)) / 7,
380 					"%02d", pt, ptlim);
381 				continue;
382 			case 'w':
383 				pt = _conv(t->tm_wday, "%d", pt, ptlim);
384 				continue;
385 			case 'X':
386 				pt = _fmt(tptr->X_fmt, t, pt, ptlim);
387 				continue;
388 			case 'x':
389 				pt = _fmt(tptr->x_fmt, t, pt, ptlim);
390 				continue;
391 			case 'y':
392 				pt = _conv((t->tm_year + TM_YEAR_BASE) % 100,
393 					"%02d", pt, ptlim);
394 				continue;
395 			case 'Y':
396 				pt = _conv(t->tm_year + TM_YEAR_BASE, "%04d",
397 					pt, ptlim);
398 				continue;
399 			case 'Z':
400 				if (t->tm_zone != NULL)
401 					pt = _add(t->tm_zone, pt, ptlim);
402 				else
403 				if (t->tm_isdst == 0 || t->tm_isdst == 1) {
404 					pt = _add(tzname[t->tm_isdst],
405 						pt, ptlim);
406 				} else  pt = _add("?", pt, ptlim);
407 				continue;
408 			case 'z':
409 				{
410 					long absoff;
411 					if (t->tm_gmtoff >= 0) {
412 						absoff = t->tm_gmtoff;
413 						pt = _add("+", pt, ptlim);
414 					} else {
415 						absoff = -t->tm_gmtoff;
416 						pt = _add("-", pt, ptlim);
417 					}
418 					pt = _conv(absoff / 3600, "%02d",
419 						pt, ptlim);
420 					pt = _conv((absoff % 3600) / 60, "%02d",
421 						pt, ptlim);
422 				};
423 				continue;
424 			case '+':
425 				pt = _fmt(tptr->date_fmt, t, pt, ptlim);
426 				continue;
427 			case '%':
428 			/*
429 			 * X311J/88-090 (4.12.3.5): if conversion char is
430 			 * undefined, behavior is undefined.  Print out the
431 			 * character itself as printf(3) also does.
432 			 */
433 			default:
434 				break;
435 			}
436 		}
437 		if (pt == ptlim)
438 			break;
439 		*pt++ = *format;
440 	}
441 	return pt;
442 }
443 
444 static char *
445 _conv(n, format, pt, ptlim)
446 	const int n;
447 	const char *const format;
448 	char *const pt;
449 	const char *const ptlim;
450 {
451 	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
452 
453 	(void) sprintf(buf, format, n);
454 	return _add(buf, pt, ptlim);
455 }
456 
457 static char *
458 _add(str, pt, ptlim)
459 	const char *str;
460 	char *pt;
461 	const char *const ptlim;
462 {
463 	while (pt < ptlim && (*pt = *str++) != '\0')
464 		++pt;
465 	return pt;
466 }
467