xref: /freebsd/lib/libc/stdtime/strftime.c (revision 5129159789cc9d7bc514e4546b88e3427695002d)
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 "private.h"
34 
35 #ifndef LIBC_SCCS
36 #ifndef lint
37 static const char	sccsid[] = "@(#)strftime.c	5.4 (Berkeley) 3/14/89";
38 #endif /* !defined lint */
39 #endif /* !defined LIBC_SCCS */
40 
41 #include "tzfile.h"
42 #include <fcntl.h>
43 #include <sys/stat.h>
44 #include "timelocal.h"
45 
46 static char *	_add P((const char *, char *, const char *));
47 static char *	_conv P((int, const char *, char *, const char *));
48 static char *	_fmt P((const char *, const struct tm *, char *, const char *));
49 
50 size_t strftime P((char *, size_t, const char *, const struct tm *));
51 
52 extern char *	tzname[];
53 
54 size_t
55 strftime(s, maxsize, format, t)
56 	char *const s;
57 	const size_t maxsize;
58 	const char *const format;
59 	const struct tm *const t;
60 {
61 	char *p;
62 
63 	tzset();
64 	p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize);
65 	if (p == s + maxsize)
66 		return 0;
67 	*p = '\0';
68 	return p - s;
69 }
70 
71 static char *
72 _fmt(format, t, pt, ptlim)
73 	const char *format;
74 	const struct tm *const t;
75 	char *pt;
76 	const char *const ptlim;
77 {
78 	int Ealternative, Oalternative;
79 
80 	for ( ; *format; ++format) {
81 		if (*format == '%') {
82 			Ealternative = 0;
83 			Oalternative = 0;
84 label:
85 			switch (*++format) {
86 			case '\0':
87 				--format;
88 				break;
89 			case 'A':
90 				pt = _add((t->tm_wday < 0 || t->tm_wday > 6) ?
91 					"?" : Locale->weekday[t->tm_wday],
92 					pt, ptlim);
93 				continue;
94 			case 'a':
95 				pt = _add((t->tm_wday < 0 || t->tm_wday > 6) ?
96 					"?" : Locale->wday[t->tm_wday],
97 					pt, ptlim);
98 				continue;
99 			case 'B':
100 				pt = _add((t->tm_mon < 0 || t->tm_mon > 11) ?
101 					"?" : (Oalternative ? Locale->alt_month :
102 					Locale->month)[t->tm_mon],
103 					pt, ptlim);
104 				continue;
105 			case 'b':
106 			case 'h':
107 				pt = _add((t->tm_mon < 0 || t->tm_mon > 11) ?
108 					"?" : Locale->mon[t->tm_mon],
109 					pt, ptlim);
110 				continue;
111 			case 'C':
112 				/*
113 				** %C used to do a...
114 				**	_fmt("%a %b %e %X %Y", t);
115 				** ...whereas now POSIX 1003.2 calls for
116 				** something completely different.
117 				** (ado, 5/24/93)
118 				*/
119 				pt = _conv((t->tm_year + TM_YEAR_BASE) / 100,
120 					"%02d", pt, ptlim);
121 				continue;
122 			case 'c':
123 				pt = _fmt(Locale->c_fmt, t, pt, ptlim);
124 				continue;
125 			case 'D':
126 				pt = _fmt("%m/%d/%y", t, pt, ptlim);
127 				continue;
128 			case 'd':
129 				pt = _conv(t->tm_mday, "%02d", pt, ptlim);
130 				continue;
131 			case 'E':
132 				if (Ealternative || Oalternative)
133 					break;
134 				Ealternative++;
135 				goto label;
136 			case 'O':
137 				/*
138 				** POSIX locale extensions, a la
139 				** Arnold Robbins' strftime version 3.0.
140 				** The sequences
141 				**      %Ec %EC %Ex %EX %Ey %EY
142 				**	%Od %oe %OH %OI %Om %OM
143 				**	%OS %Ou %OU %OV %Ow %OW %Oy
144 				** are supposed to provide alternate
145 				** representations.
146 				** (ado, 5/24/93)
147 				**
148 				** FreeBSD extensions
149 				**      %OB %Ef %EF
150 				*/
151 				if (Ealternative || Oalternative)
152 					break;
153 				Oalternative++;
154 				goto label;
155 			case 'e':
156 				pt = _conv(t->tm_mday, "%2d", pt, ptlim);
157 				continue;
158 			case 'f':
159 				if (!Ealternative)
160 					break;
161 				pt = _fmt(Locale->Ef_fmt, t, pt, ptlim);
162 				continue;
163 			case 'F':
164 				if (!Ealternative)
165 					break;
166 				pt = _fmt(Locale->EF_fmt, t, pt, ptlim);
167 				continue;
168 			case 'H':
169 				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
170 				continue;
171 			case 'I':
172 				pt = _conv((t->tm_hour % 12) ?
173 					(t->tm_hour % 12) : 12,
174 					"%02d", pt, ptlim);
175 				continue;
176 			case 'j':
177 				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
178 				continue;
179 			case 'k':
180 				/*
181 				** This used to be...
182 				**	_conv(t->tm_hour % 12 ?
183 				**		t->tm_hour % 12 : 12, 2, ' ');
184 				** ...and has been changed to the below to
185 				** match SunOS 4.1.1 and Arnold Robbins'
186 				** strftime version 3.0.  That is, "%k" and
187 				** "%l" have been swapped.
188 				** (ado, 5/24/93)
189 				*/
190 				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
191 				continue;
192 #ifdef KITCHEN_SINK
193 			case 'K':
194 				/*
195 				** After all this time, still unclaimed!
196 				*/
197 				pt = _add("kitchen sink", pt, ptlim);
198 				continue;
199 #endif /* defined KITCHEN_SINK */
200 			case 'l':
201 				/*
202 				** This used to be...
203 				**	_conv(t->tm_hour, 2, ' ');
204 				** ...and has been changed to the below to
205 				** match SunOS 4.1.1 and Arnold Robbin's
206 				** strftime version 3.0.  That is, "%k" and
207 				** "%l" have been swapped.
208 				** (ado, 5/24/93)
209 				*/
210 				pt = _conv((t->tm_hour % 12) ?
211 					(t->tm_hour % 12) : 12,
212 					"%2d", pt, ptlim);
213 				continue;
214 			case 'M':
215 				pt = _conv(t->tm_min, "%02d", pt, ptlim);
216 				continue;
217 			case 'm':
218 				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
219 				continue;
220 			case 'n':
221 				pt = _add("\n", pt, ptlim);
222 				continue;
223 			case 'p':
224 				pt = _add((t->tm_hour >= 12) ?
225 					Locale->pm :
226 					Locale->am,
227 					pt, ptlim);
228 				continue;
229 			case 'R':
230 				pt = _fmt("%H:%M", t, pt, ptlim);
231 				continue;
232 			case 'r':
233 				pt = _fmt("%I:%M:%S %p", t, pt, ptlim);
234 				continue;
235 			case 'S':
236 				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
237 				continue;
238 			case 's':
239 				{
240 					struct tm	tm;
241 					char		buf[INT_STRLEN_MAXIMUM(
242 								time_t) + 1];
243 					time_t		mkt;
244 
245 					tm = *t;
246 					mkt = mktime(&tm);
247 					if (TYPE_SIGNED(time_t))
248 						(void) sprintf(buf, "%ld",
249 							(long) mkt);
250 					else	(void) sprintf(buf, "%lu",
251 							(unsigned long) mkt);
252 					pt = _add(buf, pt, ptlim);
253 				}
254 				continue;
255 			case 'T':
256 				pt = _fmt("%H:%M:%S", t, pt, ptlim);
257 				continue;
258 			case 't':
259 				pt = _add("\t", pt, ptlim);
260 				continue;
261 			case 'U':
262 				pt = _conv((t->tm_yday + 7 - t->tm_wday) / 7,
263 					"%02d", pt, ptlim);
264 				continue;
265 			case 'u':
266 				/*
267 				** From Arnold Robbins' strftime version 3.0:
268 				** "ISO 8601: Weekday as a decimal number
269 				** [1 (Monday) - 7]"
270 				** (ado, 5/24/93)
271 				*/
272 				pt = _conv((t->tm_wday == 0) ? 7 : t->tm_wday,
273 					"%d", pt, ptlim);
274 				continue;
275 			case 'V':	/* ISO 8601 week number */
276 			case 'G':	/* ISO 8601 year (four digits) */
277 			case 'g':	/* ISO 8601 year (two digits) */
278 /*
279 ** From Arnold Robbins' strftime version 3.0:  "the week number of the
280 ** year (the first Monday as the first day of week 1) as a decimal number
281 ** (01-53)."
282 ** (ado, 1993-05-24)
283 **
284 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
285 ** "Week 01 of a year is per definition the first week which has the
286 ** Thursday in this year, which is equivalent to the week which contains
287 ** the fourth day of January. In other words, the first week of a new year
288 ** is the week which has the majority of its days in the new year. Week 01
289 ** might also contain days from the previous year and the week before week
290 ** 01 of a year is the last week (52 or 53) of the previous year even if
291 ** it contains days from the new year. A week starts with Monday (day 1)
292 ** and ends with Sunday (day 7).  For example, the first week of the year
293 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
294 ** (ado, 1996-01-02)
295 */
296 				{
297 					int	year;
298 					int	yday;
299 					int	wday;
300 					int	w;
301 
302 					year = t->tm_year + TM_YEAR_BASE;
303 					yday = t->tm_yday;
304 					wday = t->tm_wday;
305 					for ( ; ; ) {
306 						int	len;
307 						int	bot;
308 						int	top;
309 
310 						len = isleap(year) ?
311 							DAYSPERLYEAR :
312 							DAYSPERNYEAR;
313 						/*
314 						** What yday (-3 ... 3) does
315 						** the ISO year begin on?
316 						*/
317 						bot = ((yday + 11 - wday) %
318 							DAYSPERWEEK) - 3;
319 						/*
320 						** What yday does the NEXT
321 						** ISO year begin on?
322 						*/
323 						top = bot -
324 							(len % DAYSPERWEEK);
325 						if (top < -3)
326 							top += DAYSPERWEEK;
327 						top += len;
328 						if (yday >= top) {
329 							++year;
330 							w = 1;
331 							break;
332 						}
333 						if (yday >= bot) {
334 							w = 1 + ((yday - bot) /
335 								DAYSPERWEEK);
336 							break;
337 						}
338 						--year;
339 						yday += isleap(year) ?
340 							DAYSPERLYEAR :
341 							DAYSPERNYEAR;
342 					}
343 #ifdef XPG4_1994_04_09
344 					if ((w == 52
345 					     && t->tm_mon == TM_JANUARY)
346 					    || (w == 1
347 						&& t->tm_mon == TM_DECEMBER))
348 						w = 53;
349 #endif /* defined XPG4_1994_04_09 */
350 					if (*format == 'V')
351 						pt = _conv(w, "%02d",
352 							pt, ptlim);
353 					else if (*format == 'g') {
354 						pt = _conv(year % 100, "%02d",
355 							pt, ptlim);
356 					} else	pt = _conv(year, "%04d",
357 							pt, ptlim);
358 				}
359 				continue;
360 			case 'v':
361 				/*
362 				** From Arnold Robbins' strftime version 3.0:
363 				** "date as dd-bbb-YYYY"
364 				** (ado, 5/24/93)
365 				*/
366 				pt = _fmt("%e-%b-%Y", t, pt, ptlim);
367 				continue;
368 			case 'W':
369 				pt = _conv((t->tm_yday + 7 -
370 					(t->tm_wday ?
371 					(t->tm_wday - 1) : 6)) / 7,
372 					"%02d", pt, ptlim);
373 				continue;
374 			case 'w':
375 				pt = _conv(t->tm_wday, "%d", pt, ptlim);
376 				continue;
377 			case 'X':
378 				pt = _fmt(Locale->X_fmt, t, pt, ptlim);
379 				continue;
380 			case 'x':
381 				pt = _fmt(Locale->x_fmt, t, pt, ptlim);
382 				continue;
383 			case 'y':
384 				pt = _conv((t->tm_year + TM_YEAR_BASE) % 100,
385 					"%02d", pt, ptlim);
386 				continue;
387 			case 'Y':
388 				pt = _conv(t->tm_year + TM_YEAR_BASE, "%04d",
389 					pt, ptlim);
390 				continue;
391 			case 'Z':
392 				if (t->tm_zone != NULL)
393 					pt = _add(t->tm_zone, pt, ptlim);
394 				else
395 				if (t->tm_isdst == 0 || t->tm_isdst == 1) {
396 					pt = _add(tzname[t->tm_isdst],
397 						pt, ptlim);
398 				} else  pt = _add("?", pt, ptlim);
399 				continue;
400 			case '+':
401 				pt = _fmt(Locale->date_fmt, t, pt, ptlim);
402 				continue;
403 			case '%':
404 			/*
405 			 * X311J/88-090 (4.12.3.5): if conversion char is
406 			 * undefined, behavior is undefined.  Print out the
407 			 * character itself as printf(3) also does.
408 			 */
409 			default:
410 				break;
411 			}
412 		}
413 		if (pt == ptlim)
414 			break;
415 		*pt++ = *format;
416 	}
417 	return pt;
418 }
419 
420 static char *
421 _conv(n, format, pt, ptlim)
422 	const int n;
423 	const char *const format;
424 	char *const pt;
425 	const char *const ptlim;
426 {
427 	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
428 
429 	(void) sprintf(buf, format, n);
430 	return _add(buf, pt, ptlim);
431 }
432 
433 static char *
434 _add(str, pt, ptlim)
435 	const char *str;
436 	char *pt;
437 	const char *const ptlim;
438 {
439 	while (pt < ptlim && (*pt = *str++) != '\0')
440 		++pt;
441 	return pt;
442 }
443