xref: /netbsd-src/lib/libc/time/strptime.c (revision 9ee9e0d7de4c59c936a17df52be682915dc66f43) 
1 /*	$NetBSD: strptime.c,v 1.32 2009/05/01 20:15:05 ginsbach Exp $	*/
2 
3 /*-
4  * Copyright (c) 1997, 1998, 2005, 2008 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code was contributed to The NetBSD Foundation by Klaus Klein.
8  * Heavily optimised by David Laight
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 __RCSID("$NetBSD: strptime.c,v 1.32 2009/05/01 20:15:05 ginsbach Exp $");
35 #endif
36 
37 #include "namespace.h"
38 #include <sys/localedef.h>
39 #include <ctype.h>
40 #include <locale.h>
41 #include <string.h>
42 #include <time.h>
43 #include <tzfile.h>
44 #include "private.h"
45 
46 #ifdef __weak_alias
47 __weak_alias(strptime,_strptime)
48 #endif
49 
50 #define	_ctloc(x)		(_CurrentTimeLocale->x)
51 
52 /*
53  * We do not implement alternate representations. However, we always
54  * check whether a given modifier is allowed for a certain conversion.
55  */
56 #define ALT_E			0x01
57 #define ALT_O			0x02
58 #define	LEGAL_ALT(x)		{ if (alt_format & ~(x)) return NULL; }
59 
60 static char gmt[] = { "GMT" };
61 static char utc[] = { "UTC" };
62 /* RFC-822/RFC-2822 */
63 static const char * const nast[5] = {
64        "EST",    "CST",    "MST",    "PST",    "\0\0\0"
65 };
66 static const char * const nadt[5] = {
67        "EDT",    "CDT",    "MDT",    "PDT",    "\0\0\0"
68 };
69 
70 static const u_char *conv_num(const unsigned char *, int *, uint, uint);
71 static const u_char *find_string(const u_char *, int *, const char * const *,
72 	const char * const *, int);
73 
74 
75 char *
76 strptime(const char *buf, const char *fmt, struct tm *tm)
77 {
78 	unsigned char c;
79 	const unsigned char *bp, *ep;
80 	int alt_format, i, split_year = 0, neg = 0, offs;
81 	const char *new_fmt;
82 
83 	bp = (const u_char *)buf;
84 
85 	while (bp != NULL && (c = *fmt++) != '\0') {
86 		/* Clear `alternate' modifier prior to new conversion. */
87 		alt_format = 0;
88 		i = 0;
89 
90 		/* Eat up white-space. */
91 		if (isspace(c)) {
92 			while (isspace(*bp))
93 				bp++;
94 			continue;
95 		}
96 
97 		if (c != '%')
98 			goto literal;
99 
100 
101 again:		switch (c = *fmt++) {
102 		case '%':	/* "%%" is converted to "%". */
103 literal:
104 			if (c != *bp++)
105 				return NULL;
106 			LEGAL_ALT(0);
107 			continue;
108 
109 		/*
110 		 * "Alternative" modifiers. Just set the appropriate flag
111 		 * and start over again.
112 		 */
113 		case 'E':	/* "%E?" alternative conversion modifier. */
114 			LEGAL_ALT(0);
115 			alt_format |= ALT_E;
116 			goto again;
117 
118 		case 'O':	/* "%O?" alternative conversion modifier. */
119 			LEGAL_ALT(0);
120 			alt_format |= ALT_O;
121 			goto again;
122 
123 		/*
124 		 * "Complex" conversion rules, implemented through recursion.
125 		 */
126 		case 'c':	/* Date and time, using the locale's format. */
127 			new_fmt = _ctloc(d_t_fmt);
128 			goto recurse;
129 
130 		case 'D':	/* The date as "%m/%d/%y". */
131 			new_fmt = "%m/%d/%y";
132 			LEGAL_ALT(0);
133 			goto recurse;
134 
135 		case 'F':	/* The date as "%Y-%m-%d". */
136 			new_fmt = "%Y-%m-%d";
137 			LEGAL_ALT(0);
138 			goto recurse;
139 
140 		case 'R':	/* The time as "%H:%M". */
141 			new_fmt = "%H:%M";
142 			LEGAL_ALT(0);
143 			goto recurse;
144 
145 		case 'r':	/* The time in 12-hour clock representation. */
146 			new_fmt =_ctloc(t_fmt_ampm);
147 			LEGAL_ALT(0);
148 			goto recurse;
149 
150 		case 'T':	/* The time as "%H:%M:%S". */
151 			new_fmt = "%H:%M:%S";
152 			LEGAL_ALT(0);
153 			goto recurse;
154 
155 		case 'X':	/* The time, using the locale's format. */
156 			new_fmt =_ctloc(t_fmt);
157 			goto recurse;
158 
159 		case 'x':	/* The date, using the locale's format. */
160 			new_fmt =_ctloc(d_fmt);
161 		    recurse:
162 			bp = (const u_char *)strptime((const char *)bp,
163 							    new_fmt, tm);
164 			LEGAL_ALT(ALT_E);
165 			continue;
166 
167 		/*
168 		 * "Elementary" conversion rules.
169 		 */
170 		case 'A':	/* The day of week, using the locale's form. */
171 		case 'a':
172 			bp = find_string(bp, &tm->tm_wday, _ctloc(day),
173 					_ctloc(abday), 7);
174 			LEGAL_ALT(0);
175 			continue;
176 
177 		case 'B':	/* The month, using the locale's form. */
178 		case 'b':
179 		case 'h':
180 			bp = find_string(bp, &tm->tm_mon, _ctloc(mon),
181 					_ctloc(abmon), 12);
182 			LEGAL_ALT(0);
183 			continue;
184 
185 		case 'C':	/* The century number. */
186 			i = 20;
187 			bp = conv_num(bp, &i, 0, 99);
188 
189 			i = i * 100 - TM_YEAR_BASE;
190 			if (split_year)
191 				i += tm->tm_year % 100;
192 			split_year = 1;
193 			tm->tm_year = i;
194 			LEGAL_ALT(ALT_E);
195 			continue;
196 
197 		case 'd':	/* The day of month. */
198 		case 'e':
199 			bp = conv_num(bp, &tm->tm_mday, 1, 31);
200 			LEGAL_ALT(ALT_O);
201 			continue;
202 
203 		case 'k':	/* The hour (24-hour clock representation). */
204 			LEGAL_ALT(0);
205 			/* FALLTHROUGH */
206 		case 'H':
207 			bp = conv_num(bp, &tm->tm_hour, 0, 23);
208 			LEGAL_ALT(ALT_O);
209 			continue;
210 
211 		case 'l':	/* The hour (12-hour clock representation). */
212 			LEGAL_ALT(0);
213 			/* FALLTHROUGH */
214 		case 'I':
215 			bp = conv_num(bp, &tm->tm_hour, 1, 12);
216 			if (tm->tm_hour == 12)
217 				tm->tm_hour = 0;
218 			LEGAL_ALT(ALT_O);
219 			continue;
220 
221 		case 'j':	/* The day of year. */
222 			i = 1;
223 			bp = conv_num(bp, &i, 1, 366);
224 			tm->tm_yday = i - 1;
225 			LEGAL_ALT(0);
226 			continue;
227 
228 		case 'M':	/* The minute. */
229 			bp = conv_num(bp, &tm->tm_min, 0, 59);
230 			LEGAL_ALT(ALT_O);
231 			continue;
232 
233 		case 'm':	/* The month. */
234 			i = 1;
235 			bp = conv_num(bp, &i, 1, 12);
236 			tm->tm_mon = i - 1;
237 			LEGAL_ALT(ALT_O);
238 			continue;
239 
240 		case 'p':	/* The locale's equivalent of AM/PM. */
241 			bp = find_string(bp, &i, _ctloc(am_pm), NULL, 2);
242 			if (tm->tm_hour > 11)
243 				return NULL;
244 			tm->tm_hour += i * 12;
245 			LEGAL_ALT(0);
246 			continue;
247 
248 		case 'S':	/* The seconds. */
249 			bp = conv_num(bp, &tm->tm_sec, 0, 61);
250 			LEGAL_ALT(ALT_O);
251 			continue;
252 
253 		case 'U':	/* The week of year, beginning on sunday. */
254 		case 'W':	/* The week of year, beginning on monday. */
255 			/*
256 			 * XXX This is bogus, as we can not assume any valid
257 			 * information present in the tm structure at this
258 			 * point to calculate a real value, so just check the
259 			 * range for now.
260 			 */
261 			 bp = conv_num(bp, &i, 0, 53);
262 			 LEGAL_ALT(ALT_O);
263 			 continue;
264 
265 		case 'w':	/* The day of week, beginning on sunday. */
266 			bp = conv_num(bp, &tm->tm_wday, 0, 6);
267 			LEGAL_ALT(ALT_O);
268 			continue;
269 
270 		case 'u':	/* The day of week, monday = 1. */
271 			bp = conv_num(bp, &i, 1, 7);
272 			tm->tm_wday = i % 7;
273 			LEGAL_ALT(ALT_O);
274 			continue;
275 
276 		case 'g':	/* The year corresponding to the ISO week
277 				 * number but without the century.
278 				 */
279 			bp = conv_num(bp, &i, 0, 99);
280 			continue;
281 
282 		case 'G':	/* The year corresponding to the ISO week
283 				 * number with century.
284 				 */
285 			do
286 				bp++;
287 			while (isdigit(*bp));
288 			continue;
289 
290 		case 'V':	/* The ISO 8601:1988 week number as decimal */
291 			bp = conv_num(bp, &i, 0, 53);
292 			continue;
293 
294 		case 'Y':	/* The year. */
295 			i = TM_YEAR_BASE;	/* just for data sanity... */
296 			bp = conv_num(bp, &i, 0, 9999);
297 			tm->tm_year = i - TM_YEAR_BASE;
298 			LEGAL_ALT(ALT_E);
299 			continue;
300 
301 		case 'y':	/* The year within 100 years of the epoch. */
302 			/* LEGAL_ALT(ALT_E | ALT_O); */
303 			bp = conv_num(bp, &i, 0, 99);
304 
305 			if (split_year)
306 				/* preserve century */
307 				i += (tm->tm_year / 100) * 100;
308 			else {
309 				split_year = 1;
310 				if (i <= 68)
311 					i = i + 2000 - TM_YEAR_BASE;
312 				else
313 					i = i + 1900 - TM_YEAR_BASE;
314 			}
315 			tm->tm_year = i;
316 			continue;
317 
318 		case 'Z':
319 			tzset();
320 			if (strncmp((const char *)bp, gmt, 3) == 0) {
321 				tm->tm_isdst = 0;
322 #ifdef TM_GMTOFF
323 				tm->TM_GMTOFF = 0;
324 #endif
325 #ifdef TM_ZONE
326 				tm->TM_ZONE = gmt;
327 #endif
328 				bp += 3;
329 			} else {
330 				ep = find_string(bp, &i,
331 					       	 (const char * const *)tzname,
332 					       	  NULL, 2);
333 				if (ep != NULL) {
334 					tm->tm_isdst = i;
335 #ifdef TM_GMTOFF
336 					tm->TM_GMTOFF = -(timezone);
337 #endif
338 #ifdef TM_ZONE
339 					tm->TM_ZONE = tzname[i];
340 #endif
341 				}
342 				bp = ep;
343 			}
344 			continue;
345 
346 		case 'z':
347 			/*
348 			 * We recognize all ISO 8601 formats:
349 			 * Z	= Zulu time/UTC
350 			 * [+-]hhmm
351 			 * [+-]hh:mm
352 			 * [+-]hh
353 			 * We recognize all RFC-822/RFC-2822 formats:
354 			 * UT|GMT
355 			 *          North American : UTC offsets
356 			 * E[DS]T = Eastern : -4 | -5
357 			 * C[DS]T = Central : -5 | -6
358 			 * M[DS]T = Mountain: -6 | -7
359 			 * P[DS]T = Pacific : -7 | -8
360 			 *          Military
361 			 * [A-IL-M] = -1 ... -9 (J not used)
362 			 * [N-Y]  = +1 ... +12
363 			 */
364 			while (isspace(*bp))
365 				bp++;
366 
367 			switch (*bp++) {
368 			case 'G':
369 				if (*bp++ != 'M')
370 					return NULL;
371 				/*FALLTHROUGH*/
372 			case 'U':
373 				if (*bp++ != 'T')
374 					return NULL;
375 				/*FALLTHROUGH*/
376 			case 'Z':
377 				tm->tm_isdst = 0;
378 #ifdef TM_GMTOFF
379 				tm->TM_GMTOFF = 0;
380 #endif
381 #ifdef TM_ZONE
382 				tm->TM_ZONE = utc;
383 #endif
384 				continue;
385 			case '+':
386 				neg = 0;
387 				break;
388 			case '-':
389 				neg = 1;
390 				break;
391 			default:
392 				--bp;
393 				ep = find_string(bp, &i, nast, NULL, 4);
394 				if (ep != NULL) {
395 #ifdef TM_GMTOFF
396 					tm->TM_GMTOFF = -5 - i;
397 #endif
398 #ifdef TM_ZONE
399 					tm->TM_ZONE = __UNCONST(nast[i]);
400 #endif
401 					bp = ep;
402 					continue;
403 				}
404 				ep = find_string(bp, &i, nadt, NULL, 4);
405 				if (ep != NULL) {
406 					tm->tm_isdst = 1;
407 #ifdef TM_GMTOFF
408 					tm->TM_GMTOFF = -4 - i;
409 #endif
410 #ifdef TM_ZONE
411 					tm->TM_ZONE = __UNCONST(nadt[i]);
412 #endif
413 					bp = ep;
414 					continue;
415 				}
416 
417 				if ((*bp >= 'A' && *bp <= 'I') ||
418 				    (*bp >= 'L' && *bp <= 'Y')) {
419 #ifdef TM_GMTOFF
420 					/* Argh! No 'J'! */
421 					if (*bp >= 'A' && *bp <= 'I')
422 						tm->TM_GMTOFF =
423 						    ('A' - 1) - (int)*bp;
424 					else if (*bp >= 'L' && *bp <= 'M')
425 						tm->TM_GMTOFF = 'A' - (int)*bp;
426 					else if (*bp >= 'N' && *bp <= 'Y')
427 						tm->TM_GMTOFF = (int)*bp - 'M';
428 #endif
429 #ifdef TM_ZONE
430 					tm->TM_ZONE = NULL; /* XXX */
431 #endif
432 					bp++;
433 					continue;
434 				}
435 				return NULL;
436 			}
437 			offs = 0;
438 			for (i = 0; i < 4; ) {
439 				if (isdigit(*bp)) {
440 					offs = offs * 10 + (*bp++ - '0');
441 					i++;
442 					continue;
443 				}
444 				if (i == 2 && *bp == ':') {
445 					bp++;
446 					continue;
447 				}
448 				break;
449 			}
450 			switch (i) {
451 			case 2:
452 				offs *= 100;
453 				break;
454 			case 4:
455 				i = offs % 100;
456 				if (i >= 60)
457 					return NULL;
458 				/* Convert minutes into decimal */
459 				offs = (offs / 100) * 100 + (i * 50) / 30;
460 				break;
461 			default:
462 				return NULL;
463 			}
464 			if (neg)
465 				offs = -offs;
466 			tm->tm_isdst = 0;	/* XXX */
467 #ifdef TM_GMTOFF
468 			tm->TM_GMTOFF = offs;
469 #endif
470 #ifdef TM_ZONE
471 			tm->TM_ZONE = NULL;	/* XXX */
472 #endif
473 			continue;
474 
475 		/*
476 		 * Miscellaneous conversions.
477 		 */
478 		case 'n':	/* Any kind of white-space. */
479 		case 't':
480 			while (isspace(*bp))
481 				bp++;
482 			LEGAL_ALT(0);
483 			continue;
484 
485 
486 		default:	/* Unknown/unsupported conversion. */
487 			return NULL;
488 		}
489 	}
490 
491 	return __UNCONST(bp);
492 }
493 
494 
495 static const u_char *
496 conv_num(const unsigned char *buf, int *dest, uint llim, uint ulim)
497 {
498 	uint result = 0;
499 	unsigned char ch;
500 
501 	/* The limit also determines the number of valid digits. */
502 	uint rulim = ulim;
503 
504 	ch = *buf;
505 	if (ch < '0' || ch > '9')
506 		return NULL;
507 
508 	do {
509 		result *= 10;
510 		result += ch - '0';
511 		rulim /= 10;
512 		ch = *++buf;
513 	} while ((result * 10 <= ulim) && rulim && ch >= '0' && ch <= '9');
514 
515 	if (result < llim || result > ulim)
516 		return NULL;
517 
518 	*dest = result;
519 	return buf;
520 }
521 
522 static const u_char *
523 find_string(const u_char *bp, int *tgt, const char * const *n1,
524 		const char * const *n2, int c)
525 {
526 	int i;
527 	unsigned int len;
528 
529 	/* check full name - then abbreviated ones */
530 	for (; n1 != NULL; n1 = n2, n2 = NULL) {
531 		for (i = 0; i < c; i++, n1++) {
532 			len = strlen(*n1);
533 			if (strncasecmp(*n1, (const char *)bp, len) == 0) {
534 				*tgt = i;
535 				return bp + len;
536 			}
537 		}
538 	}
539 
540 	/* Nothing matched */
541 	return NULL;
542 }
543