xref: /freebsd/lib/libc/stdtime/strftime.c (revision 3ff369fed2a08f32dda232c10470b949bef9489f)
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 #ifndef lint
19 #ifndef NOID
20 static const char	elsieid[] = "@(#)strftime.c	7.38";
21 /*
22 ** Based on the UCB version with the ID appearing below.
23 ** This is ANSIish only when "multibyte character == plain character".
24 */
25 #endif /* !defined NOID */
26 #endif /* !defined lint */
27 
28 #include "namespace.h"
29 #include "private.h"
30 
31 #if defined(LIBC_SCCS) && !defined(lint)
32 static const char	sccsid[] = "@(#)strftime.c	5.4 (Berkeley) 3/14/89";
33 #endif /* LIBC_SCCS and not lint */
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36 
37 #include "tzfile.h"
38 #include <fcntl.h>
39 #include <sys/stat.h>
40 #include "un-namespace.h"
41 #include "timelocal.h"
42 
43 static char *	_add(const char *, char *, const char *);
44 static char *	_conv(int, const char *, char *, const char *);
45 static char *	_fmt(const char *, const struct tm *, char *, const char *);
46 
47 size_t strftime(char *, size_t, const char *, const struct tm *);
48 
49 extern char *	tzname[];
50 
51 size_t
52 strftime(s, maxsize, format, t)
53 	char *const s;
54 	const size_t maxsize;
55 	const char *const format;
56 	const struct tm *const t;
57 {
58 	char *p;
59 
60 	tzset();
61 	p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize);
62 	if (p == s + maxsize)
63 		return 0;
64 	*p = '\0';
65 	return p - s;
66 }
67 
68 static char *
69 _fmt(format, t, pt, ptlim)
70 	const char *format;
71 	const struct tm *const t;
72 	char *pt;
73 	const char *const ptlim;
74 {
75 	int Ealternative, Oalternative;
76 	struct lc_time_T *tptr = __get_current_time_locale();
77 
78 	for ( ; *format; ++format) {
79 		if (*format == '%') {
80 			Ealternative = 0;
81 			Oalternative = 0;
82 label:
83 			switch (*++format) {
84 			case '\0':
85 				--format;
86 				break;
87 			case 'A':
88 				pt = _add((t->tm_wday < 0 || t->tm_wday > 6) ?
89 					"?" : tptr->weekday[t->tm_wday],
90 					pt, ptlim);
91 				continue;
92 			case 'a':
93 				pt = _add((t->tm_wday < 0 || t->tm_wday > 6) ?
94 					"?" : tptr->wday[t->tm_wday],
95 					pt, ptlim);
96 				continue;
97 			case 'B':
98 				pt = _add((t->tm_mon < 0 || t->tm_mon > 11) ?
99 					"?" : (Oalternative ? tptr->alt_month :
100 					tptr->month)[t->tm_mon],
101 					pt, ptlim);
102 				continue;
103 			case 'b':
104 			case 'h':
105 				pt = _add((t->tm_mon < 0 || t->tm_mon > 11) ?
106 					"?" : tptr->mon[t->tm_mon],
107 					pt, ptlim);
108 				continue;
109 			case 'C':
110 				/*
111 				** %C used to do a...
112 				**	_fmt("%a %b %e %X %Y", t);
113 				** ...whereas now POSIX 1003.2 calls for
114 				** something completely different.
115 				** (ado, 5/24/93)
116 				*/
117 				pt = _conv((t->tm_year + TM_YEAR_BASE) / 100,
118 					"%02d", pt, ptlim);
119 				continue;
120 			case 'c':
121 				pt = _fmt(tptr->c_fmt, t, pt, ptlim);
122 				continue;
123 			case 'D':
124 				pt = _fmt("%m/%d/%y", t, pt, ptlim);
125 				continue;
126 			case 'd':
127 				pt = _conv(t->tm_mday, "%02d", pt, ptlim);
128 				continue;
129 			case 'E':
130 				if (Ealternative || Oalternative)
131 					break;
132 				Ealternative++;
133 				goto label;
134 			case 'O':
135 				/*
136 				** POSIX locale extensions, a la
137 				** Arnold Robbins' strftime version 3.0.
138 				** The sequences
139 				**      %Ec %EC %Ex %EX %Ey %EY
140 				**	%Od %oe %OH %OI %Om %OM
141 				**	%OS %Ou %OU %OV %Ow %OW %Oy
142 				** are supposed to provide alternate
143 				** representations.
144 				** (ado, 5/24/93)
145 				**
146 				** FreeBSD extensions
147 				**      %OB %Ef %EF
148 				*/
149 				if (Ealternative || Oalternative)
150 					break;
151 				Oalternative++;
152 				goto label;
153 			case 'e':
154 				pt = _conv(t->tm_mday, "%2d", pt, ptlim);
155 				continue;
156 			case 'F':
157 				pt = _fmt("%Y-%m-%d", t, pt, ptlim);
158 				continue;
159 			case 'H':
160 				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
161 				continue;
162 			case 'I':
163 				pt = _conv((t->tm_hour % 12) ?
164 					(t->tm_hour % 12) : 12,
165 					"%02d", pt, ptlim);
166 				continue;
167 			case 'j':
168 				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
169 				continue;
170 			case 'k':
171 				/*
172 				** This used to be...
173 				**	_conv(t->tm_hour % 12 ?
174 				**		t->tm_hour % 12 : 12, 2, ' ');
175 				** ...and has been changed to the below to
176 				** match SunOS 4.1.1 and Arnold Robbins'
177 				** strftime version 3.0.  That is, "%k" and
178 				** "%l" have been swapped.
179 				** (ado, 5/24/93)
180 				*/
181 				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
182 				continue;
183 #ifdef KITCHEN_SINK
184 			case 'K':
185 				/*
186 				** After all this time, still unclaimed!
187 				*/
188 				pt = _add("kitchen sink", pt, ptlim);
189 				continue;
190 #endif /* defined KITCHEN_SINK */
191 			case 'l':
192 				/*
193 				** This used to be...
194 				**	_conv(t->tm_hour, 2, ' ');
195 				** ...and has been changed to the below to
196 				** match SunOS 4.1.1 and Arnold Robbin's
197 				** strftime version 3.0.  That is, "%k" and
198 				** "%l" have been swapped.
199 				** (ado, 5/24/93)
200 				*/
201 				pt = _conv((t->tm_hour % 12) ?
202 					(t->tm_hour % 12) : 12,
203 					"%2d", pt, ptlim);
204 				continue;
205 			case 'M':
206 				pt = _conv(t->tm_min, "%02d", pt, ptlim);
207 				continue;
208 			case 'm':
209 				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
210 				continue;
211 			case 'n':
212 				pt = _add("\n", pt, ptlim);
213 				continue;
214 			case 'p':
215 				pt = _add((t->tm_hour >= 12) ?
216 					tptr->pm :
217 					tptr->am,
218 					pt, ptlim);
219 				continue;
220 			case 'R':
221 				pt = _fmt("%H:%M", t, pt, ptlim);
222 				continue;
223 			case 'r':
224 				pt = _fmt(tptr->ampm_fmt, t, pt, ptlim);
225 				continue;
226 			case 'S':
227 				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
228 				continue;
229 			case 's':
230 				{
231 					struct tm	tm;
232 					char		buf[INT_STRLEN_MAXIMUM(
233 								time_t) + 1];
234 					time_t		mkt;
235 
236 					tm = *t;
237 					mkt = mktime(&tm);
238 					if (TYPE_SIGNED(time_t))
239 						(void) sprintf(buf, "%ld",
240 							(long) mkt);
241 					else	(void) sprintf(buf, "%lu",
242 							(unsigned long) mkt);
243 					pt = _add(buf, pt, ptlim);
244 				}
245 				continue;
246 			case 'T':
247 				pt = _fmt("%H:%M:%S", t, pt, ptlim);
248 				continue;
249 			case 't':
250 				pt = _add("\t", pt, ptlim);
251 				continue;
252 			case 'U':
253 				pt = _conv((t->tm_yday + 7 - t->tm_wday) / 7,
254 					"%02d", pt, ptlim);
255 				continue;
256 			case 'u':
257 				/*
258 				** From Arnold Robbins' strftime version 3.0:
259 				** "ISO 8601: Weekday as a decimal number
260 				** [1 (Monday) - 7]"
261 				** (ado, 5/24/93)
262 				*/
263 				pt = _conv((t->tm_wday == 0) ? 7 : t->tm_wday,
264 					"%d", pt, ptlim);
265 				continue;
266 			case 'V':	/* ISO 8601 week number */
267 			case 'G':	/* ISO 8601 year (four digits) */
268 			case 'g':	/* ISO 8601 year (two digits) */
269 /*
270 ** From Arnold Robbins' strftime version 3.0:  "the week number of the
271 ** year (the first Monday as the first day of week 1) as a decimal number
272 ** (01-53)."
273 ** (ado, 1993-05-24)
274 **
275 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
276 ** "Week 01 of a year is per definition the first week which has the
277 ** Thursday in this year, which is equivalent to the week which contains
278 ** the fourth day of January. In other words, the first week of a new year
279 ** is the week which has the majority of its days in the new year. Week 01
280 ** might also contain days from the previous year and the week before week
281 ** 01 of a year is the last week (52 or 53) of the previous year even if
282 ** it contains days from the new year. A week starts with Monday (day 1)
283 ** and ends with Sunday (day 7).  For example, the first week of the year
284 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
285 ** (ado, 1996-01-02)
286 */
287 				{
288 					int	year;
289 					int	yday;
290 					int	wday;
291 					int	w;
292 
293 					year = t->tm_year + TM_YEAR_BASE;
294 					yday = t->tm_yday;
295 					wday = t->tm_wday;
296 					for ( ; ; ) {
297 						int	len;
298 						int	bot;
299 						int	top;
300 
301 						len = isleap(year) ?
302 							DAYSPERLYEAR :
303 							DAYSPERNYEAR;
304 						/*
305 						** What yday (-3 ... 3) does
306 						** the ISO year begin on?
307 						*/
308 						bot = ((yday + 11 - wday) %
309 							DAYSPERWEEK) - 3;
310 						/*
311 						** What yday does the NEXT
312 						** ISO year begin on?
313 						*/
314 						top = bot -
315 							(len % DAYSPERWEEK);
316 						if (top < -3)
317 							top += DAYSPERWEEK;
318 						top += len;
319 						if (yday >= top) {
320 							++year;
321 							w = 1;
322 							break;
323 						}
324 						if (yday >= bot) {
325 							w = 1 + ((yday - bot) /
326 								DAYSPERWEEK);
327 							break;
328 						}
329 						--year;
330 						yday += isleap(year) ?
331 							DAYSPERLYEAR :
332 							DAYSPERNYEAR;
333 					}
334 #ifdef XPG4_1994_04_09
335 					if ((w == 52
336 					     && t->tm_mon == TM_JANUARY)
337 					    || (w == 1
338 						&& t->tm_mon == TM_DECEMBER))
339 						w = 53;
340 #endif /* defined XPG4_1994_04_09 */
341 					if (*format == 'V')
342 						pt = _conv(w, "%02d",
343 							pt, ptlim);
344 					else if (*format == 'g') {
345 						pt = _conv(year % 100, "%02d",
346 							pt, ptlim);
347 					} else	pt = _conv(year, "%04d",
348 							pt, ptlim);
349 				}
350 				continue;
351 			case 'v':
352 				/*
353 				** From Arnold Robbins' strftime version 3.0:
354 				** "date as dd-bbb-YYYY"
355 				** (ado, 5/24/93)
356 				*/
357 				pt = _fmt("%e-%b-%Y", t, pt, ptlim);
358 				continue;
359 			case 'W':
360 				pt = _conv((t->tm_yday + 7 -
361 					(t->tm_wday ?
362 					(t->tm_wday - 1) : 6)) / 7,
363 					"%02d", pt, ptlim);
364 				continue;
365 			case 'w':
366 				pt = _conv(t->tm_wday, "%d", pt, ptlim);
367 				continue;
368 			case 'X':
369 				pt = _fmt(tptr->X_fmt, t, pt, ptlim);
370 				continue;
371 			case 'x':
372 				pt = _fmt(tptr->x_fmt, t, pt, ptlim);
373 				continue;
374 			case 'y':
375 				pt = _conv((t->tm_year + TM_YEAR_BASE) % 100,
376 					"%02d", pt, ptlim);
377 				continue;
378 			case 'Y':
379 				pt = _conv(t->tm_year + TM_YEAR_BASE, "%04d",
380 					pt, ptlim);
381 				continue;
382 			case 'Z':
383 				if (t->tm_zone != NULL)
384 					pt = _add(t->tm_zone, pt, ptlim);
385 				else
386 				if (t->tm_isdst == 0 || t->tm_isdst == 1) {
387 					pt = _add(tzname[t->tm_isdst],
388 						pt, ptlim);
389 				} else  pt = _add("?", pt, ptlim);
390 				continue;
391 			case 'z':
392 				{
393 					long absoff;
394 					if (t->tm_gmtoff >= 0) {
395 						absoff = t->tm_gmtoff;
396 						pt = _add("+", pt, ptlim);
397 					} else {
398 						absoff = -t->tm_gmtoff;
399 						pt = _add("-", pt, ptlim);
400 					}
401 					pt = _conv(absoff / 3600, "%02d",
402 						pt, ptlim);
403 					pt = _conv((absoff % 3600) / 60, "%02d",
404 						pt, ptlim);
405 				};
406 				continue;
407 			case '+':
408 				pt = _fmt(tptr->date_fmt, t, pt, ptlim);
409 				continue;
410 			case '%':
411 			/*
412 			 * X311J/88-090 (4.12.3.5): if conversion char is
413 			 * undefined, behavior is undefined.  Print out the
414 			 * character itself as printf(3) also does.
415 			 */
416 			default:
417 				break;
418 			}
419 		}
420 		if (pt == ptlim)
421 			break;
422 		*pt++ = *format;
423 	}
424 	return pt;
425 }
426 
427 static char *
428 _conv(n, format, pt, ptlim)
429 	const int n;
430 	const char *const format;
431 	char *const pt;
432 	const char *const ptlim;
433 {
434 	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
435 
436 	(void) sprintf(buf, format, n);
437 	return _add(buf, pt, ptlim);
438 }
439 
440 static char *
441 _add(str, pt, ptlim)
442 	const char *str;
443 	char *pt;
444 	const char *const ptlim;
445 {
446 	while (pt < ptlim && (*pt = *str++) != '\0')
447 		++pt;
448 	return pt;
449 }
450