strftime.c revision 130461 
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
20static const char	elsieid[] = "@(#)strftime.c	7.64";
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)
32static 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: head/lib/libc/stdtime/strftime.c 130461 2004-06-14 10:31:52Z stefanf $");
36
37#include "tzfile.h"
38#include <fcntl.h>
39#include <sys/stat.h>
40#include "un-namespace.h"
41#include "timelocal.h"
42
43static char *	_add(const char *, char *, const char *);
44static char *	_conv(int, const char *, char *, const char *);
45static char *	_fmt(const char *, const struct tm *, char *, const char *, int *);
46
47size_t strftime(char * __restrict, size_t, const char * __restrict,
48    const struct tm * __restrict);
49
50extern char *	tzname[];
51
52#ifndef YEAR_2000_NAME
53#define YEAR_2000_NAME	"CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
54#endif /* !defined YEAR_2000_NAME */
55
56
57#define IN_NONE	0
58#define IN_SOME	1
59#define IN_THIS	2
60#define IN_ALL	3
61
62size_t
63strftime(char * __restrict s, size_t maxsize, const char * __restrict format,
64    const struct tm * __restrict t)
65{
66	char *	p;
67	int	warn;
68
69	tzset();
70	warn = IN_NONE;
71	p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn);
72#ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
73	if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
74		(void) fprintf(stderr, "\n");
75		if (format == NULL)
76			(void) fprintf(stderr, "NULL strftime format ");
77		else	(void) fprintf(stderr, "strftime format \"%s\" ",
78				format);
79		(void) fprintf(stderr, "yields only two digits of years in ");
80		if (warn == IN_SOME)
81			(void) fprintf(stderr, "some locales");
82		else if (warn == IN_THIS)
83			(void) fprintf(stderr, "the current locale");
84		else	(void) fprintf(stderr, "all locales");
85		(void) fprintf(stderr, "\n");
86	}
87#endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
88	if (p == s + maxsize)
89		return 0;
90	*p = '\0';
91	return p - s;
92}
93
94static char *
95_fmt(format, t, pt, ptlim, warnp)
96const char *		format;
97const struct tm * const	t;
98char *			pt;
99const char * const	ptlim;
100int *			warnp;
101{
102	int Ealternative, Oalternative;
103	struct lc_time_T *tptr = __get_current_time_locale();
104
105	for ( ; *format; ++format) {
106		if (*format == '%') {
107			Ealternative = 0;
108			Oalternative = 0;
109label:
110			switch (*++format) {
111			case '\0':
112				--format;
113				break;
114			case 'A':
115				pt = _add((t->tm_wday < 0 ||
116					t->tm_wday >= DAYSPERWEEK) ?
117					"?" : tptr->weekday[t->tm_wday],
118					pt, ptlim);
119				continue;
120			case 'a':
121				pt = _add((t->tm_wday < 0 ||
122					t->tm_wday >= DAYSPERWEEK) ?
123					"?" : tptr->wday[t->tm_wday],
124					pt, ptlim);
125				continue;
126			case 'B':
127				pt = _add((t->tm_mon < 0 ||
128					t->tm_mon >= MONSPERYEAR) ?
129					"?" : (Oalternative ? tptr->alt_month :
130					tptr->month)[t->tm_mon],
131					pt, ptlim);
132				continue;
133			case 'b':
134			case 'h':
135				pt = _add((t->tm_mon < 0 ||
136					t->tm_mon >= MONSPERYEAR) ?
137					"?" : tptr->mon[t->tm_mon],
138					pt, ptlim);
139				continue;
140			case 'C':
141				/*
142				** %C used to do a...
143				**	_fmt("%a %b %e %X %Y", t);
144				** ...whereas now POSIX 1003.2 calls for
145				** something completely different.
146				** (ado, 1993-05-24)
147				*/
148				pt = _conv((t->tm_year + TM_YEAR_BASE) / 100,
149					"%02d", pt, ptlim);
150				continue;
151			case 'c':
152				{
153				int warn2 = IN_SOME;
154
155				pt = _fmt(tptr->c_fmt, t, pt, ptlim, warnp);
156				if (warn2 == IN_ALL)
157					warn2 = IN_THIS;
158				if (warn2 > *warnp)
159					*warnp = warn2;
160				}
161				continue;
162			case 'D':
163				pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
164				continue;
165			case 'd':
166				pt = _conv(t->tm_mday, "%02d", pt, ptlim);
167				continue;
168			case 'E':
169				if (Ealternative || Oalternative)
170					break;
171				Ealternative++;
172				goto label;
173			case 'O':
174				/*
175				** C99 locale modifiers.
176				** The sequences
177				**	%Ec %EC %Ex %EX %Ey %EY
178				**	%Od %oe %OH %OI %Om %OM
179				**	%OS %Ou %OU %OV %Ow %OW %Oy
180				** are supposed to provide alternate
181				** representations.
182				**
183				** FreeBSD extension
184				**      %OB
185				*/
186				if (Ealternative || Oalternative)
187					break;
188				Oalternative++;
189				goto label;
190			case 'e':
191				pt = _conv(t->tm_mday, "%2d", pt, ptlim);
192				continue;
193			case 'F':
194				pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
195				continue;
196			case 'H':
197				pt = _conv(t->tm_hour, "%02d", pt, ptlim);
198				continue;
199			case 'I':
200				pt = _conv((t->tm_hour % 12) ?
201					(t->tm_hour % 12) : 12,
202					"%02d", pt, ptlim);
203				continue;
204			case 'j':
205				pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
206				continue;
207			case 'k':
208				/*
209				** This used to be...
210				**	_conv(t->tm_hour % 12 ?
211				**		t->tm_hour % 12 : 12, 2, ' ');
212				** ...and has been changed to the below to
213				** match SunOS 4.1.1 and Arnold Robbins'
214				** strftime version 3.0.  That is, "%k" and
215				** "%l" have been swapped.
216				** (ado, 1993-05-24)
217				*/
218				pt = _conv(t->tm_hour, "%2d", pt, ptlim);
219				continue;
220#ifdef KITCHEN_SINK
221			case 'K':
222				/*
223				** After all this time, still unclaimed!
224				*/
225				pt = _add("kitchen sink", pt, ptlim);
226				continue;
227#endif /* defined KITCHEN_SINK */
228			case 'l':
229				/*
230				** This used to be...
231				**	_conv(t->tm_hour, 2, ' ');
232				** ...and has been changed to the below to
233				** match SunOS 4.1.1 and Arnold Robbin's
234				** strftime version 3.0.  That is, "%k" and
235				** "%l" have been swapped.
236				** (ado, 1993-05-24)
237				*/
238				pt = _conv((t->tm_hour % 12) ?
239					(t->tm_hour % 12) : 12,
240					"%2d", pt, ptlim);
241				continue;
242			case 'M':
243				pt = _conv(t->tm_min, "%02d", pt, ptlim);
244				continue;
245			case 'm':
246				pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
247				continue;
248			case 'n':
249				pt = _add("\n", pt, ptlim);
250				continue;
251			case 'p':
252				pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
253					tptr->pm :
254					tptr->am,
255					pt, ptlim);
256				continue;
257			case 'R':
258				pt = _fmt("%H:%M", t, pt, ptlim, warnp);
259				continue;
260			case 'r':
261				pt = _fmt(tptr->ampm_fmt, t, pt, ptlim,
262					warnp);
263				continue;
264			case 'S':
265				pt = _conv(t->tm_sec, "%02d", pt, ptlim);
266				continue;
267			case 's':
268				{
269					struct tm	tm;
270					char		buf[INT_STRLEN_MAXIMUM(
271								time_t) + 1];
272					time_t		mkt;
273
274					tm = *t;
275					mkt = mktime(&tm);
276					if (TYPE_SIGNED(time_t))
277						(void) sprintf(buf, "%ld",
278							(long) mkt);
279					else	(void) sprintf(buf, "%lu",
280							(unsigned long) mkt);
281					pt = _add(buf, pt, ptlim);
282				}
283				continue;
284			case 'T':
285				pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
286				continue;
287			case 't':
288				pt = _add("\t", pt, ptlim);
289				continue;
290			case 'U':
291				pt = _conv((t->tm_yday + DAYSPERWEEK -
292					t->tm_wday) / DAYSPERWEEK,
293					"%02d", pt, ptlim);
294				continue;
295			case 'u':
296				/*
297				** From Arnold Robbins' strftime version 3.0:
298				** "ISO 8601: Weekday as a decimal number
299				** [1 (Monday) - 7]"
300				** (ado, 1993-05-24)
301				*/
302				pt = _conv((t->tm_wday == 0) ?
303					DAYSPERWEEK : t->tm_wday,
304					"%d", pt, ptlim);
305				continue;
306			case 'V':	/* ISO 8601 week number */
307			case 'G':	/* ISO 8601 year (four digits) */
308			case 'g':	/* ISO 8601 year (two digits) */
309/*
310** From Arnold Robbins' strftime version 3.0:  "the week number of the
311** year (the first Monday as the first day of week 1) as a decimal number
312** (01-53)."
313** (ado, 1993-05-24)
314**
315** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
316** "Week 01 of a year is per definition the first week which has the
317** Thursday in this year, which is equivalent to the week which contains
318** the fourth day of January. In other words, the first week of a new year
319** is the week which has the majority of its days in the new year. Week 01
320** might also contain days from the previous year and the week before week
321** 01 of a year is the last week (52 or 53) of the previous year even if
322** it contains days from the new year. A week starts with Monday (day 1)
323** and ends with Sunday (day 7).  For example, the first week of the year
324** 1997 lasts from 1996-12-30 to 1997-01-05..."
325** (ado, 1996-01-02)
326*/
327				{
328					int	year;
329					int	yday;
330					int	wday;
331					int	w;
332
333					year = t->tm_year + TM_YEAR_BASE;
334					yday = t->tm_yday;
335					wday = t->tm_wday;
336					for ( ; ; ) {
337						int	len;
338						int	bot;
339						int	top;
340
341						len = isleap(year) ?
342							DAYSPERLYEAR :
343							DAYSPERNYEAR;
344						/*
345						** What yday (-3 ... 3) does
346						** the ISO year begin on?
347						*/
348						bot = ((yday + 11 - wday) %
349							DAYSPERWEEK) - 3;
350						/*
351						** What yday does the NEXT
352						** ISO year begin on?
353						*/
354						top = bot -
355							(len % DAYSPERWEEK);
356						if (top < -3)
357							top += DAYSPERWEEK;
358						top += len;
359						if (yday >= top) {
360							++year;
361							w = 1;
362							break;
363						}
364						if (yday >= bot) {
365							w = 1 + ((yday - bot) /
366								DAYSPERWEEK);
367							break;
368						}
369						--year;
370						yday += isleap(year) ?
371							DAYSPERLYEAR :
372							DAYSPERNYEAR;
373					}
374#ifdef XPG4_1994_04_09
375					if ((w == 52
376					     && t->tm_mon == TM_JANUARY)
377					    || (w == 1
378						&& t->tm_mon == TM_DECEMBER))
379						w = 53;
380#endif /* defined XPG4_1994_04_09 */
381					if (*format == 'V')
382						pt = _conv(w, "%02d",
383							pt, ptlim);
384					else if (*format == 'g') {
385						*warnp = IN_ALL;
386						pt = _conv(year % 100, "%02d",
387							pt, ptlim);
388					} else	pt = _conv(year, "%04d",
389							pt, ptlim);
390				}
391				continue;
392			case 'v':
393				/*
394				** From Arnold Robbins' strftime version 3.0:
395				** "date as dd-bbb-YYYY"
396				** (ado, 1993-05-24)
397				*/
398				pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
399				continue;
400			case 'W':
401				pt = _conv((t->tm_yday + DAYSPERWEEK -
402					(t->tm_wday ?
403					(t->tm_wday - 1) :
404					(DAYSPERWEEK - 1))) / DAYSPERWEEK,
405					"%02d", pt, ptlim);
406				continue;
407			case 'w':
408				pt = _conv(t->tm_wday, "%d", pt, ptlim);
409				continue;
410			case 'X':
411				pt = _fmt(tptr->X_fmt, t, pt, ptlim, warnp);
412				continue;
413			case 'x':
414				{
415				int	warn2 = IN_SOME;
416
417				pt = _fmt(tptr->x_fmt, t, pt, ptlim, &warn2);
418				if (warn2 == IN_ALL)
419					warn2 = IN_THIS;
420				if (warn2 > *warnp)
421					*warnp = warn2;
422				}
423				continue;
424			case 'y':
425				*warnp = IN_ALL;
426				pt = _conv((t->tm_year + TM_YEAR_BASE) % 100,
427					"%02d", pt, ptlim);
428				continue;
429			case 'Y':
430				pt = _conv(t->tm_year + TM_YEAR_BASE, "%04d",
431					pt, ptlim);
432				continue;
433			case 'Z':
434#ifdef TM_ZONE
435				if (t->TM_ZONE != NULL)
436					pt = _add(t->TM_ZONE, pt, ptlim);
437				else
438#endif /* defined TM_ZONE */
439				if (t->tm_isdst >= 0)
440					pt = _add(tzname[t->tm_isdst != 0],
441						pt, ptlim);
442				/*
443				** C99 says that %Z must be replaced by the
444				** empty string if the time zone is not
445				** determinable.
446				*/
447				continue;
448			case 'z':
449				{
450				int		diff;
451				char const *	sign;
452
453				if (t->tm_isdst < 0)
454					continue;
455#ifdef TM_GMTOFF
456				diff = t->TM_GMTOFF;
457#else /* !defined TM_GMTOFF */
458				/*
459				** C99 says that the UTC offset must
460				** be computed by looking only at
461				** tm_isdst.  This requirement is
462				** incorrect, since it means the code
463				** must rely on magic (in this case
464				** altzone and timezone), and the
465				** magic might not have the correct
466				** offset.  Doing things correctly is
467				** tricky and requires disobeying C99;
468				** see GNU C strftime for details.
469				** For now, punt and conform to the
470				** standard, even though it's incorrect.
471				**
472				** C99 says that %z must be replaced by the
473				** empty string if the time zone is not
474				** determinable, so output nothing if the
475				** appropriate variables are not available.
476				*/
477				if (t->tm_isdst == 0)
478#ifdef USG_COMPAT
479					diff = -timezone;
480#else /* !defined USG_COMPAT */
481					continue;
482#endif /* !defined USG_COMPAT */
483				else
484#ifdef ALTZONE
485					diff = -altzone;
486#else /* !defined ALTZONE */
487					continue;
488#endif /* !defined ALTZONE */
489#endif /* !defined TM_GMTOFF */
490				if (diff < 0) {
491					sign = "-";
492					diff = -diff;
493				} else	sign = "+";
494				pt = _add(sign, pt, ptlim);
495				diff /= 60;
496				pt = _conv((diff/60)*100 + diff%60,
497					"%04d", pt, ptlim);
498				}
499				continue;
500			case '+':
501				pt = _fmt(tptr->date_fmt, t, pt, ptlim,
502					warnp);
503				continue;
504			case '%':
505			/*
506			** X311J/88-090 (4.12.3.5): if conversion char is
507			** undefined, behavior is undefined.  Print out the
508			** character itself as printf(3) also does.
509			*/
510			default:
511				break;
512			}
513		}
514		if (pt == ptlim)
515			break;
516		*pt++ = *format;
517	}
518	return pt;
519}
520
521static char *
522_conv(n, format, pt, ptlim)
523const int		n;
524const char * const	format;
525char * const		pt;
526const char * const	ptlim;
527{
528	char	buf[INT_STRLEN_MAXIMUM(int) + 1];
529
530	(void) sprintf(buf, format, n);
531	return _add(buf, pt, ptlim);
532}
533
534static char *
535_add(str, pt, ptlim)
536const char *		str;
537char *			pt;
538const char * const	ptlim;
539{
540	while (pt < ptlim && (*pt = *str++) != '\0')
541		++pt;
542	return pt;
543}
544