xref: /netbsd-src/lib/libc/time/strftime.c (revision d0fed6c87ddc40a8bffa6f99e7433ddfc864dd83)
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, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #if defined(LIBC_SCCS) && !defined(lint)
35 /*static char *sccsid = "from: @(#)strftime.c	5.11 (Berkeley) 2/24/91";*/
36 static char *rcsid = "$Id: strftime.c,v 1.1 1997/04/23 01:18:05 mrg Exp $";
37 #endif /* LIBC_SCCS and not lint */
38 
39 #include <sys/localedef.h>
40 #include <locale.h>
41 #include <string.h>
42 #include <tzfile.h>
43 #include <time.h>
44 
45 static size_t gsize;
46 static char *pt;
47 static int _add(), _conv(), _secs();
48 static size_t _fmt();
49 
50 size_t
51 strftime(s, maxsize, format, t)
52 	char *s;
53 	size_t maxsize;
54 	const char *format;
55 	const struct tm *t;
56 {
57 	tzset();
58 
59 	pt = s;
60 	if ((gsize = maxsize) < 1)
61 		return(0);
62 	if (_fmt(format, t)) {
63 		*pt = '\0';
64 		return(maxsize - gsize);
65 	}
66 	return(0);
67 }
68 
69 #define SUN_WEEK(t)	(((t)->tm_yday + 7 - \
70 				((t)->tm_wday)) / 7)
71 #define MON_WEEK(t)	(((t)->tm_yday + 7 - \
72 				((t)->tm_wday ? (t)->tm_wday - 1 : 6)) / 7)
73 static size_t
74 _fmt(format, t)
75 	register const char *format;
76 	const struct tm *t;
77 {
78 	for (; *format; ++format) {
79 		if (*format == '%') {
80 			++format;
81 			if (*format == 'E') {
82 				/* Alternate Era */
83 				++format;
84 			} else if (*format == 'O') {
85 				/* Alternate numeric symbols */
86 				++format;
87 			}
88 			switch(*format) {
89 			case '\0':
90 				--format;
91 				break;
92 			case 'A':
93 				if (t->tm_wday < 0 || t->tm_wday > 6)
94 					return(0);
95 				if (!_add(_CurrentTimeLocale->day[t->tm_wday]))
96 					return(0);
97 				continue;
98 			case 'a':
99 				if (t->tm_wday < 0 || t->tm_wday > 6)
100 					return(0);
101 				if (!_add(_CurrentTimeLocale->abday[t->tm_wday]))
102 					return(0);
103 				continue;
104 			case 'B':
105 				if (t->tm_mon < 0 || t->tm_mon > 11)
106 					return(0);
107 				if (!_add(_CurrentTimeLocale->mon[t->tm_mon]))
108 					return(0);
109 				continue;
110 			case 'b':
111 			case 'h':
112 				if (t->tm_mon < 0 || t->tm_mon > 11)
113 					return(0);
114 				if (!_add(_CurrentTimeLocale->abmon[t->tm_mon]))
115 					return(0);
116 				continue;
117 			case 'C':
118 				if (!_conv((t->tm_year + TM_YEAR_BASE) / 100,
119 				    2, '0'))
120 					return(0);
121 				continue;
122 			case 'c':
123 				if (!_fmt(_CurrentTimeLocale->d_t_fmt, t))
124 					return(0);
125 				continue;
126 			case 'D':
127 				if (!_fmt("%m/%d/%y", t))
128 					return(0);
129 				continue;
130 			case 'd':
131 				if (!_conv(t->tm_mday, 2, '0'))
132 					return(0);
133 				continue;
134 			case 'e':
135 				if (!_conv(t->tm_mday, 2, ' '))
136 					return(0);
137 				continue;
138 			case 'H':
139 				if (!_conv(t->tm_hour, 2, '0'))
140 					return(0);
141 				continue;
142 			case 'I':
143 				if (!_conv(t->tm_hour % 12 ?
144 				    t->tm_hour % 12 : 12, 2, '0'))
145 					return(0);
146 				continue;
147 			case 'j':
148 				if (!_conv(t->tm_yday + 1, 3, '0'))
149 					return(0);
150 				continue;
151 			case 'k':
152 				if (!_conv(t->tm_hour, 2, ' '))
153 					return(0);
154 				continue;
155 			case 'l':
156 				if (!_conv(t->tm_hour % 12 ?
157 				    t->tm_hour % 12: 12, 2, ' '))
158 					return(0);
159 				continue;
160 			case 'M':
161 				if (!_conv(t->tm_min, 2, '0'))
162 					return(0);
163 				continue;
164 			case 'm':
165 				if (!_conv(t->tm_mon + 1, 2, '0'))
166 					return(0);
167 				continue;
168 			case 'n':
169 				if (!_add("\n"))
170 					return(0);
171 				continue;
172 			case 'p':
173 				if (!_add(_CurrentTimeLocale->am_pm[t->tm_hour >= 12]))
174 					return(0);
175 				continue;
176 			case 'R':
177 				if (!_fmt("%H:%M", t))
178 					return(0);
179 				continue;
180 			case 'r':
181 				if (!_fmt(_CurrentTimeLocale->t_fmt_ampm, t))
182 					return(0);
183 				continue;
184 			case 'S':
185 				if (!_conv(t->tm_sec, 2, '0'))
186 					return(0);
187 				continue;
188 			case 's':
189 				if (!_secs(t))
190 					return(0);
191 				continue;
192 			case 'T':
193 				if (!_fmt("%H:%M:%S", t))
194 					return(0);
195 				continue;
196 			case 't':
197 				if (!_add("\t"))
198 					return(0);
199 				continue;
200 			case 'U':
201 				if (!_conv(SUN_WEEK(t), 2, '0'))
202 					return(0);
203 				continue;
204 			case 'u':
205 				if (!_conv(t->tm_wday ? t->tm_wday : 7, 1, '0'))
206 					return(0);
207 				continue;
208 			case 'V':
209 				{
210 				/* ISO 8601 Week Of Year:
211 				   If the week (Monday - Sunday) containing
212 				   January 1 has four or more days in the new
213 				   year, then it is week 1; otherwise it is
214 				   week 53 of the previous year and the next
215 				   week is week one. */
216 
217 				int week = MON_WEEK(t);
218 
219 				int days = (((t)->tm_yday + 7 - \
220                                 ((t)->tm_wday ? (t)->tm_wday - 1 : 6)) % 7);
221 
222 
223 				if (days >= 4) {
224 					week++;
225 				} else if (week == 0) {
226 					week = 53;
227 				}
228 
229 				if (!_conv(week, 2, '0'))
230 					return(0);
231 				continue;
232 				}
233 			case 'W':
234 				if (!_conv(MON_WEEK(t), 2, '0'))
235 					return(0);
236 				continue;
237 			case 'w':
238 				if (!_conv(t->tm_wday, 1, '0'))
239 					return(0);
240 				continue;
241 			case 'x':
242 				if (!_fmt(_CurrentTimeLocale->d_fmt, t))
243 					return(0);
244 				continue;
245 			case 'X':
246 				if (!_fmt(_CurrentTimeLocale->t_fmt, t))
247 					return(0);
248 				continue;
249 			case 'y':
250 				if (!_conv((t->tm_year + TM_YEAR_BASE) % 100,
251 				    2, '0'))
252 					return(0);
253 				continue;
254 			case 'Y':
255 				if (!_conv((t->tm_year + TM_YEAR_BASE), 4, '0'))
256 					return(0);
257 				continue;
258 			case 'Z':
259 				if (t->tm_zone && !_add(t->tm_zone))
260 					return(0);
261 				continue;
262 			case '%':
263 			/*
264 			 * X311J/88-090 (4.12.3.5): if conversion char is
265 			 * undefined, behavior is undefined.  Print out the
266 			 * character itself as printf(3) does.
267 			 */
268 			default:
269 				break;
270 			}
271 		}
272 		if (!gsize--)
273 			return(0);
274 		*pt++ = *format;
275 	}
276 	return(gsize);
277 }
278 
279 static int
280 _secs(t)
281 	const struct tm *t;
282 {
283 	static char buf[15];
284 	register time_t s;
285 	register char *p;
286 	struct tm tmp;
287 
288 	/* Make a copy, mktime(3) modifies the tm struct. */
289 	tmp = *t;
290 	s = mktime(&tmp);
291 	for (p = buf + sizeof(buf) - 2; s > 0 && p > buf; s /= 10)
292 		*p-- = s % 10 + '0';
293 	return(_add(++p));
294 }
295 
296 static int
297 _conv(n, digits, pad)
298 	int n, digits;
299 	char pad;
300 {
301 	static char buf[10];
302 	register char *p;
303 
304 	for (p = buf + sizeof(buf) - 2; n > 0 && p > buf; n /= 10, --digits)
305 		*p-- = n % 10 + '0';
306 	while (p > buf && digits-- > 0)
307 		*p-- = pad;
308 	return(_add(++p));
309 }
310 
311 static int
312 _add(str)
313 	register const char *str;
314 {
315 	for (;; ++pt, --gsize) {
316 		if (!gsize)
317 			return(0);
318 		if (!(*pt = *str++))
319 			return(1);
320 	}
321 }
322