1 /* $NetBSD: tm.c,v 1.1 2024/02/18 20:57:50 christos Exp $ */
2
3 /*
4 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
5 *
6 * SPDX-License-Identifier: MPL-2.0 AND BSD-2-Clause
7 *
8 * This Source Code Form is subject to the terms of the Mozilla Public
9 * License, v. 2.0. If a copy of the MPL was not distributed with this
10 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
11 *
12 * See the COPYRIGHT file distributed with this work for additional
13 * information regarding copyright ownership.
14 */
15
16 /*-
17 * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
18 * All rights reserved.
19 *
20 * This code was contributed to The NetBSD Foundation by Klaus Klein.
21 *
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
24 * are met:
25 * 1. Redistributions of source code must retain the above copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 *
31 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
32 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
33 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
34 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
35 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
36 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
37 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
38 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
39 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41 * POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 #include <ctype.h>
45 #include <stdio.h>
46 #include <stdlib.h>
47 #include <string.h>
48 #include <time.h>
49
50 #include <isc/tm.h>
51 #include <isc/util.h>
52
53 /*
54 * Portable conversion routines for struct tm, replacing
55 * timegm() and strptime(), which are not available on all
56 * platforms and don't always behave the same way when they
57 * are.
58 */
59
60 /*
61 * We do not implement alternate representations. However, we always
62 * check whether a given modifier is allowed for a certain conversion.
63 */
64 #define ALT_E 0x01
65 #define ALT_O 0x02
66 #define LEGAL_ALT(x) \
67 { \
68 if ((alt_format & ~(x)) != 0) \
69 return ((0)); \
70 }
71
72 #ifndef TM_YEAR_BASE
73 #define TM_YEAR_BASE 1900
74 #endif /* ifndef TM_YEAR_BASE */
75
76 static const char *day[7] = { "Sunday", "Monday", "Tuesday", "Wednesday",
77 "Thursday", "Friday", "Saturday" };
78 static const char *abday[7] = {
79 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
80 };
81 static const char *mon[12] = {
82 "January", "February", "March", "April", "May", "June",
83 "July", "August", "September", "October", "November", "December"
84 };
85 static const char *abmon[12] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
86 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
87 static const char *am_pm[2] = { "AM", "PM" };
88
89 static int
conv_num(const char ** buf,int * dest,int llim,int ulim)90 conv_num(const char **buf, int *dest, int llim, int ulim) {
91 int result = 0;
92
93 /* The limit also determines the number of valid digits. */
94 int rulim = ulim;
95
96 if (!isdigit((unsigned char)**buf)) {
97 return (0);
98 }
99
100 do {
101 result *= 10;
102 result += *(*buf)++ - '0';
103 rulim /= 10;
104 } while ((result * 10 <= ulim) && rulim && **buf >= '0' &&
105 **buf <= '9');
106
107 if (result < llim || result > ulim) {
108 return (0);
109 }
110
111 *dest = result;
112 return (1);
113 }
114
115 time_t
isc_tm_timegm(struct tm * tm)116 isc_tm_timegm(struct tm *tm) {
117 time_t ret;
118 int i, yday = 0, leapday;
119 int mdays[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30 };
120
121 leapday = ((((tm->tm_year + 1900) % 4) == 0 &&
122 ((tm->tm_year + 1900) % 100) != 0) ||
123 ((tm->tm_year + 1900) % 400) == 0)
124 ? 1
125 : 0;
126 mdays[1] += leapday;
127
128 yday = tm->tm_mday - 1;
129 for (i = 1; i <= tm->tm_mon; i++) {
130 yday += mdays[i - 1];
131 }
132 ret = tm->tm_sec + (60 * tm->tm_min) + (3600 * tm->tm_hour) +
133 (86400 *
134 (yday + ((tm->tm_year - 70) * 365) + ((tm->tm_year - 69) / 4) -
135 ((tm->tm_year - 1) / 100) + ((tm->tm_year + 299) / 400)));
136 return (ret);
137 }
138
139 char *
isc_tm_strptime(const char * buf,const char * fmt,struct tm * tm)140 isc_tm_strptime(const char *buf, const char *fmt, struct tm *tm) {
141 char c, *ret;
142 const char *bp;
143 size_t len = 0;
144 int alt_format, i, split_year = 0;
145
146 REQUIRE(buf != NULL);
147 REQUIRE(fmt != NULL);
148 REQUIRE(tm != NULL);
149
150 memset(tm, 0, sizeof(struct tm));
151
152 bp = buf;
153
154 while ((c = *fmt) != '\0') {
155 /* Clear `alternate' modifier prior to new conversion. */
156 alt_format = 0;
157
158 /* Eat up white-space. */
159 if (isspace((unsigned char)c)) {
160 while (isspace((unsigned char)*bp)) {
161 bp++;
162 }
163
164 fmt++;
165 continue;
166 }
167
168 if ((c = *fmt++) != '%') {
169 goto literal;
170 }
171
172 again:
173 switch (c = *fmt++) {
174 case '%': /* "%%" is converted to "%". */
175 literal:
176 if (c != *bp++) {
177 return (0);
178 }
179 break;
180
181 /*
182 * "Alternative" modifiers. Just set the appropriate flag
183 * and start over again.
184 */
185 case 'E': /* "%E?" alternative conversion modifier. */
186 LEGAL_ALT(0);
187 alt_format |= ALT_E;
188 goto again;
189
190 case 'O': /* "%O?" alternative conversion modifier. */
191 LEGAL_ALT(0);
192 alt_format |= ALT_O;
193 goto again;
194
195 /*
196 * "Complex" conversion rules, implemented through recursion.
197 */
198 case 'c': /* Date and time, using the locale's format. */
199 LEGAL_ALT(ALT_E);
200 if (!(bp = isc_tm_strptime(bp, "%x %X", tm))) {
201 return (0);
202 }
203 break;
204
205 case 'D': /* The date as "%m/%d/%y". */
206 LEGAL_ALT(0);
207 if (!(bp = isc_tm_strptime(bp, "%m/%d/%y", tm))) {
208 return (0);
209 }
210 break;
211
212 case 'R': /* The time as "%H:%M". */
213 LEGAL_ALT(0);
214 if (!(bp = isc_tm_strptime(bp, "%H:%M", tm))) {
215 return (0);
216 }
217 break;
218
219 case 'r': /* The time in 12-hour clock representation. */
220 LEGAL_ALT(0);
221 if (!(bp = isc_tm_strptime(bp, "%I:%M:%S %p", tm))) {
222 return (0);
223 }
224 break;
225
226 case 'T': /* The time as "%H:%M:%S". */
227 LEGAL_ALT(0);
228 if (!(bp = isc_tm_strptime(bp, "%H:%M:%S", tm))) {
229 return (0);
230 }
231 break;
232
233 case 'X': /* The time, using the locale's format. */
234 LEGAL_ALT(ALT_E);
235 if (!(bp = isc_tm_strptime(bp, "%H:%M:%S", tm))) {
236 return (0);
237 }
238 break;
239
240 case 'x': /* The date, using the locale's format. */
241 LEGAL_ALT(ALT_E);
242 if (!(bp = isc_tm_strptime(bp, "%m/%d/%y", tm))) {
243 return (0);
244 }
245 break;
246
247 /*
248 * "Elementary" conversion rules.
249 */
250 case 'A': /* The day of week, using the locale's form. */
251 case 'a':
252 LEGAL_ALT(0);
253 for (i = 0; i < 7; i++) {
254 /* Full name. */
255 len = strlen(day[i]);
256 if (strncasecmp(day[i], bp, len) == 0) {
257 break;
258 }
259
260 /* Abbreviated name. */
261 len = strlen(abday[i]);
262 if (strncasecmp(abday[i], bp, len) == 0) {
263 break;
264 }
265 }
266
267 /* Nothing matched. */
268 if (i == 7) {
269 return (0);
270 }
271
272 tm->tm_wday = i;
273 bp += len;
274 break;
275
276 case 'B': /* The month, using the locale's form. */
277 case 'b':
278 case 'h':
279 LEGAL_ALT(0);
280 for (i = 0; i < 12; i++) {
281 /* Full name. */
282 len = strlen(mon[i]);
283 if (strncasecmp(mon[i], bp, len) == 0) {
284 break;
285 }
286
287 /* Abbreviated name. */
288 len = strlen(abmon[i]);
289 if (strncasecmp(abmon[i], bp, len) == 0) {
290 break;
291 }
292 }
293
294 /* Nothing matched. */
295 if (i == 12) {
296 return (0);
297 }
298
299 tm->tm_mon = i;
300 bp += len;
301 break;
302
303 case 'C': /* The century number. */
304 LEGAL_ALT(ALT_E);
305 if (!(conv_num(&bp, &i, 0, 99))) {
306 return (0);
307 }
308
309 if (split_year) {
310 tm->tm_year = (tm->tm_year % 100) + (i * 100);
311 } else {
312 tm->tm_year = i * 100;
313 split_year = 1;
314 }
315 break;
316
317 case 'd': /* The day of month. */
318 case 'e':
319 LEGAL_ALT(ALT_O);
320 if (!(conv_num(&bp, &tm->tm_mday, 1, 31))) {
321 return (0);
322 }
323 break;
324
325 case 'k': /* The hour (24-hour clock representation). */
326 LEGAL_ALT(0);
327 FALLTHROUGH;
328 case 'H':
329 LEGAL_ALT(ALT_O);
330 if (!(conv_num(&bp, &tm->tm_hour, 0, 23))) {
331 return (0);
332 }
333 break;
334
335 case 'l': /* The hour (12-hour clock representation). */
336 LEGAL_ALT(0);
337 FALLTHROUGH;
338 case 'I':
339 LEGAL_ALT(ALT_O);
340 if (!(conv_num(&bp, &tm->tm_hour, 1, 12))) {
341 return (0);
342 }
343 if (tm->tm_hour == 12) {
344 tm->tm_hour = 0;
345 }
346 break;
347
348 case 'j': /* The day of year. */
349 LEGAL_ALT(0);
350 if (!(conv_num(&bp, &i, 1, 366))) {
351 return (0);
352 }
353 tm->tm_yday = i - 1;
354 break;
355
356 case 'M': /* The minute. */
357 LEGAL_ALT(ALT_O);
358 if (!(conv_num(&bp, &tm->tm_min, 0, 59))) {
359 return (0);
360 }
361 break;
362
363 case 'm': /* The month. */
364 LEGAL_ALT(ALT_O);
365 if (!(conv_num(&bp, &i, 1, 12))) {
366 return (0);
367 }
368 tm->tm_mon = i - 1;
369 break;
370
371 case 'p': /* The locale's equivalent of AM/PM. */
372 LEGAL_ALT(0);
373 /* AM? */
374 if (strcasecmp(am_pm[0], bp) == 0) {
375 if (tm->tm_hour > 11) {
376 return (0);
377 }
378
379 bp += strlen(am_pm[0]);
380 break;
381 }
382 /* PM? */
383 else if (strcasecmp(am_pm[1], bp) == 0)
384 {
385 if (tm->tm_hour > 11) {
386 return (0);
387 }
388
389 tm->tm_hour += 12;
390 bp += strlen(am_pm[1]);
391 break;
392 }
393
394 /* Nothing matched. */
395 return (0);
396
397 case 'S': /* The seconds. */
398 LEGAL_ALT(ALT_O);
399 if (!(conv_num(&bp, &tm->tm_sec, 0, 61))) {
400 return (0);
401 }
402 break;
403
404 case 'U': /* The week of year, beginning on sunday. */
405 case 'W': /* The week of year, beginning on monday. */
406 LEGAL_ALT(ALT_O);
407 /*
408 * XXX This is bogus, as we can not assume any valid
409 * information present in the tm structure at this
410 * point to calculate a real value, so just check the
411 * range for now.
412 */
413 if (!(conv_num(&bp, &i, 0, 53))) {
414 return (0);
415 }
416 break;
417
418 case 'w': /* The day of week, beginning on sunday. */
419 LEGAL_ALT(ALT_O);
420 if (!(conv_num(&bp, &tm->tm_wday, 0, 6))) {
421 return (0);
422 }
423 break;
424
425 case 'Y': /* The year. */
426 LEGAL_ALT(ALT_E);
427 if (!(conv_num(&bp, &i, 0, 9999))) {
428 return (0);
429 }
430
431 tm->tm_year = i - TM_YEAR_BASE;
432 break;
433
434 case 'y': /* The year within 100 years of the epoch. */
435 LEGAL_ALT(ALT_E | ALT_O);
436 if (!(conv_num(&bp, &i, 0, 99))) {
437 return (0);
438 }
439
440 if (split_year) {
441 tm->tm_year = ((tm->tm_year / 100) * 100) + i;
442 break;
443 }
444 split_year = 1;
445 if (i <= 68) {
446 tm->tm_year = i + 2000 - TM_YEAR_BASE;
447 } else {
448 tm->tm_year = i + 1900 - TM_YEAR_BASE;
449 }
450 break;
451
452 /*
453 * Miscellaneous conversions.
454 */
455 case 'n': /* Any kind of white-space. */
456 case 't':
457 LEGAL_ALT(0);
458 while (isspace((unsigned char)*bp)) {
459 bp++;
460 }
461 break;
462
463 default: /* Unknown/unsupported conversion. */
464 return (0);
465 }
466 }
467
468 /* LINTED functional specification */
469 DE_CONST(bp, ret);
470 return (ret);
471 }
472