xref: /freebsd/lib/libc/stdtime/strftime.c (revision 5521ff5a4d1929056e7ffc982fac3341ca54df7c)
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 				pt = _fmt("%Y-%m-%d", t, pt, ptlim);
163 				continue;
164 			case 'H':
165 				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
166 				continue;
167 			case 'I':
168 				pt = _conv((t->tm_hour % 12) ?
169 					(t->tm_hour % 12) : 12,
170 					"%02d", pt, ptlim);
171 				continue;
172 			case 'j':
173 				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
174 				continue;
175 			case 'k':
176 				/*
177 				** This used to be...
178 				**	_conv(t->tm_hour % 12 ?
179 				**		t->tm_hour % 12 : 12, 2, ' ');
180 				** ...and has been changed to the below to
181 				** match SunOS 4.1.1 and Arnold Robbins'
182 				** strftime version 3.0.  That is, "%k" and
183 				** "%l" have been swapped.
184 				** (ado, 5/24/93)
185 				*/
186 				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
187 				continue;
188 #ifdef KITCHEN_SINK
189 			case 'K':
190 				/*
191 				** After all this time, still unclaimed!
192 				*/
193 				pt = _add("kitchen sink", pt, ptlim);
194 				continue;
195 #endif /* defined KITCHEN_SINK */
196 			case 'l':
197 				/*
198 				** This used to be...
199 				**	_conv(t->tm_hour, 2, ' ');
200 				** ...and has been changed to the below to
201 				** match SunOS 4.1.1 and Arnold Robbin's
202 				** strftime version 3.0.  That is, "%k" and
203 				** "%l" have been swapped.
204 				** (ado, 5/24/93)
205 				*/
206 				pt = _conv((t->tm_hour % 12) ?
207 					(t->tm_hour % 12) : 12,
208 					"%2d", pt, ptlim);
209 				continue;
210 			case 'M':
211 				pt = _conv(t->tm_min, "%02d", pt, ptlim);
212 				continue;
213 			case 'm':
214 				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
215 				continue;
216 			case 'n':
217 				pt = _add("\n", pt, ptlim);
218 				continue;
219 			case 'p':
220 				pt = _add((t->tm_hour >= 12) ?
221 					tptr->pm :
222 					tptr->am,
223 					pt, ptlim);
224 				continue;
225 			case 'R':
226 				pt = _fmt("%H:%M", t, pt, ptlim);
227 				continue;
228 			case 'r':
229 				pt = _fmt(tptr->ampm_fmt, t, pt, ptlim);
230 				continue;
231 			case 'S':
232 				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
233 				continue;
234 			case 's':
235 				{
236 					struct tm	tm;
237 					char		buf[INT_STRLEN_MAXIMUM(
238 								time_t) + 1];
239 					time_t		mkt;
240 
241 					tm = *t;
242 					mkt = mktime(&tm);
243 					if (TYPE_SIGNED(time_t))
244 						(void) sprintf(buf, "%ld",
245 							(long) mkt);
246 					else	(void) sprintf(buf, "%lu",
247 							(unsigned long) mkt);
248 					pt = _add(buf, pt, ptlim);
249 				}
250 				continue;
251 			case 'T':
252 				pt = _fmt("%H:%M:%S", t, pt, ptlim);
253 				continue;
254 			case 't':
255 				pt = _add("\t", pt, ptlim);
256 				continue;
257 			case 'U':
258 				pt = _conv((t->tm_yday + 7 - t->tm_wday) / 7,
259 					"%02d", pt, ptlim);
260 				continue;
261 			case 'u':
262 				/*
263 				** From Arnold Robbins' strftime version 3.0:
264 				** "ISO 8601: Weekday as a decimal number
265 				** [1 (Monday) - 7]"
266 				** (ado, 5/24/93)
267 				*/
268 				pt = _conv((t->tm_wday == 0) ? 7 : t->tm_wday,
269 					"%d", pt, ptlim);
270 				continue;
271 			case 'V':	/* ISO 8601 week number */
272 			case 'G':	/* ISO 8601 year (four digits) */
273 			case 'g':	/* ISO 8601 year (two digits) */
274 /*
275 ** From Arnold Robbins' strftime version 3.0:  "the week number of the
276 ** year (the first Monday as the first day of week 1) as a decimal number
277 ** (01-53)."
278 ** (ado, 1993-05-24)
279 **
280 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
281 ** "Week 01 of a year is per definition the first week which has the
282 ** Thursday in this year, which is equivalent to the week which contains
283 ** the fourth day of January. In other words, the first week of a new year
284 ** is the week which has the majority of its days in the new year. Week 01
285 ** might also contain days from the previous year and the week before week
286 ** 01 of a year is the last week (52 or 53) of the previous year even if
287 ** it contains days from the new year. A week starts with Monday (day 1)
288 ** and ends with Sunday (day 7).  For example, the first week of the year
289 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
290 ** (ado, 1996-01-02)
291 */
292 				{
293 					int	year;
294 					int	yday;
295 					int	wday;
296 					int	w;
297 
298 					year = t->tm_year + TM_YEAR_BASE;
299 					yday = t->tm_yday;
300 					wday = t->tm_wday;
301 					for ( ; ; ) {
302 						int	len;
303 						int	bot;
304 						int	top;
305 
306 						len = isleap(year) ?
307 							DAYSPERLYEAR :
308 							DAYSPERNYEAR;
309 						/*
310 						** What yday (-3 ... 3) does
311 						** the ISO year begin on?
312 						*/
313 						bot = ((yday + 11 - wday) %
314 							DAYSPERWEEK) - 3;
315 						/*
316 						** What yday does the NEXT
317 						** ISO year begin on?
318 						*/
319 						top = bot -
320 							(len % DAYSPERWEEK);
321 						if (top < -3)
322 							top += DAYSPERWEEK;
323 						top += len;
324 						if (yday >= top) {
325 							++year;
326 							w = 1;
327 							break;
328 						}
329 						if (yday >= bot) {
330 							w = 1 + ((yday - bot) /
331 								DAYSPERWEEK);
332 							break;
333 						}
334 						--year;
335 						yday += isleap(year) ?
336 							DAYSPERLYEAR :
337 							DAYSPERNYEAR;
338 					}
339 #ifdef XPG4_1994_04_09
340 					if ((w == 52
341 					     && t->tm_mon == TM_JANUARY)
342 					    || (w == 1
343 						&& t->tm_mon == TM_DECEMBER))
344 						w = 53;
345 #endif /* defined XPG4_1994_04_09 */
346 					if (*format == 'V')
347 						pt = _conv(w, "%02d",
348 							pt, ptlim);
349 					else if (*format == 'g') {
350 						pt = _conv(year % 100, "%02d",
351 							pt, ptlim);
352 					} else	pt = _conv(year, "%04d",
353 							pt, ptlim);
354 				}
355 				continue;
356 			case 'v':
357 				/*
358 				** From Arnold Robbins' strftime version 3.0:
359 				** "date as dd-bbb-YYYY"
360 				** (ado, 5/24/93)
361 				*/
362 				pt = _fmt("%e-%b-%Y", t, pt, ptlim);
363 				continue;
364 			case 'W':
365 				pt = _conv((t->tm_yday + 7 -
366 					(t->tm_wday ?
367 					(t->tm_wday - 1) : 6)) / 7,
368 					"%02d", pt, ptlim);
369 				continue;
370 			case 'w':
371 				pt = _conv(t->tm_wday, "%d", pt, ptlim);
372 				continue;
373 			case 'X':
374 				pt = _fmt(tptr->X_fmt, t, pt, ptlim);
375 				continue;
376 			case 'x':
377 				pt = _fmt(tptr->x_fmt, t, pt, ptlim);
378 				continue;
379 			case 'y':
380 				pt = _conv((t->tm_year + TM_YEAR_BASE) % 100,
381 					"%02d", pt, ptlim);
382 				continue;
383 			case 'Y':
384 				pt = _conv(t->tm_year + TM_YEAR_BASE, "%04d",
385 					pt, ptlim);
386 				continue;
387 			case 'Z':
388 				if (t->tm_zone != NULL)
389 					pt = _add(t->tm_zone, pt, ptlim);
390 				else
391 				if (t->tm_isdst == 0 || t->tm_isdst == 1) {
392 					pt = _add(tzname[t->tm_isdst],
393 						pt, ptlim);
394 				} else  pt = _add("?", pt, ptlim);
395 				continue;
396 			case 'z':
397 				{
398 					long absoff;
399 					if (t->tm_gmtoff >= 0) {
400 						absoff = t->tm_gmtoff;
401 						pt = _add("+", pt, ptlim);
402 					} else {
403 						absoff = -t->tm_gmtoff;
404 						pt = _add("-", pt, ptlim);
405 					}
406 					pt = _conv(absoff / 3600, "%02d",
407 						pt, ptlim);
408 					pt = _conv((absoff % 3600) / 60, "%02d",
409 						pt, ptlim);
410 				};
411 				continue;
412 			case '+':
413 				pt = _fmt(tptr->date_fmt, t, pt, ptlim);
414 				continue;
415 			case '%':
416 			/*
417 			 * X311J/88-090 (4.12.3.5): if conversion char is
418 			 * undefined, behavior is undefined.  Print out the
419 			 * character itself as printf(3) also does.
420 			 */
421 			default:
422 				break;
423 			}
424 		}
425 		if (pt == ptlim)
426 			break;
427 		*pt++ = *format;
428 	}
429 	return pt;
430 }
431 
432 static char *
433 _conv(n, format, pt, ptlim)
434 	const int n;
435 	const char *const format;
436 	char *const pt;
437 	const char *const ptlim;
438 {
439 	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
440 
441 	(void) sprintf(buf, format, n);
442 	return _add(buf, pt, ptlim);
443 }
444 
445 static char *
446 _add(str, pt, ptlim)
447 	const char *str;
448 	char *pt;
449 	const char *const ptlim;
450 {
451 	while (pt < ptlim && (*pt = *str++) != '\0')
452 		++pt;
453 	return pt;
454 }
455