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Add generic 'strbuf_readlink()' helper function
[git/dscho.git] / date.c
blob950b88fdcf74f550a582684f1702ffb58c62c7f9
1 /*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
6
7 #include "cache.h"
8
9 /*
10 * This is like mktime, but without normalization of tm_wday and tm_yday.
11 */
12 time_t tm_to_time_t(const struct tm *tm)
13 {
14 static const int mdays[] = {
15 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
16 };
17 int year = tm->tm_year - 70;
18 int month = tm->tm_mon;
19 int day = tm->tm_mday;
20
21 if (year < 0 || year > 129) /* algo only works for 1970-2099 */
22 return -1;
23 if (month < 0 || month > 11) /* array bounds */
24 return -1;
25 if (month < 2 || (year + 2) % 4)
26 day--;
27 return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
28 tm->tm_hour * 60*60 + tm->tm_min * 60 + tm->tm_sec;
29 }
30
31 static const char *month_names[] = {
32 "January", "February", "March", "April", "May", "June",
33 "July", "August", "September", "October", "November", "December"
34 };
35
36 static const char *weekday_names[] = {
37 "Sundays", "Mondays", "Tuesdays", "Wednesdays", "Thursdays", "Fridays", "Saturdays"
38 };
39
40 static time_t gm_time_t(unsigned long time, int tz)
41 {
42 int minutes;
43
44 minutes = tz < 0 ? -tz : tz;
45 minutes = (minutes / 100)*60 + (minutes % 100);
46 minutes = tz < 0 ? -minutes : minutes;
47 return time + minutes * 60;
48 }
49
50 /*
51 * The "tz" thing is passed in as this strange "decimal parse of tz"
52 * thing, which means that tz -0100 is passed in as the integer -100,
53 * even though it means "sixty minutes off"
54 */
55 static struct tm *time_to_tm(unsigned long time, int tz)
56 {
57 time_t t = gm_time_t(time, tz);
58 return gmtime(&t);
59 }
60
61 /*
62 * What value of "tz" was in effect back then at "time" in the
63 * local timezone?
64 */
65 static int local_tzoffset(unsigned long time)
66 {
67 time_t t, t_local;
68 struct tm tm;
69 int offset, eastwest;
70
71 t = time;
72 localtime_r(&t, &tm);
73 t_local = tm_to_time_t(&tm);
74
75 if (t_local < t) {
76 eastwest = -1;
77 offset = t - t_local;
78 } else {
79 eastwest = 1;
80 offset = t_local - t;
81 }
82 offset /= 60; /* in minutes */
83 offset = (offset % 60) + ((offset / 60) * 100);
84 return offset * eastwest;
85 }
86
87 const char *show_date(unsigned long time, int tz, enum date_mode mode)
88 {
89 struct tm *tm;
90 static char timebuf[200];
91
92 if (mode == DATE_RELATIVE) {
93 unsigned long diff;
94 struct timeval now;
95 gettimeofday(&now, NULL);
96 if (now.tv_sec < time)
97 return "in the future";
98 diff = now.tv_sec - time;
99 if (diff < 90) {
100 snprintf(timebuf, sizeof(timebuf), "%lu seconds ago", diff);
101 return timebuf;
102 }
103 /* Turn it into minutes */
104 diff = (diff + 30) / 60;
105 if (diff < 90) {
106 snprintf(timebuf, sizeof(timebuf), "%lu minutes ago", diff);
107 return timebuf;
108 }
109 /* Turn it into hours */
110 diff = (diff + 30) / 60;
111 if (diff < 36) {
112 snprintf(timebuf, sizeof(timebuf), "%lu hours ago", diff);
113 return timebuf;
114 }
115 /* We deal with number of days from here on */
116 diff = (diff + 12) / 24;
117 if (diff < 14) {
118 snprintf(timebuf, sizeof(timebuf), "%lu days ago", diff);
119 return timebuf;
120 }
121 /* Say weeks for the past 10 weeks or so */
122 if (diff < 70) {
123 snprintf(timebuf, sizeof(timebuf), "%lu weeks ago", (diff + 3) / 7);
124 return timebuf;
125 }
126 /* Say months for the past 12 months or so */
127 if (diff < 360) {
128 snprintf(timebuf, sizeof(timebuf), "%lu months ago", (diff + 15) / 30);
129 return timebuf;
130 }
131 /* Else fall back on absolute format.. */
132 }
133
134 if (mode == DATE_LOCAL)
135 tz = local_tzoffset(time);
136
137 tm = time_to_tm(time, tz);
138 if (!tm)
139 return NULL;
140 if (mode == DATE_SHORT)
141 sprintf(timebuf, "%04d-%02d-%02d", tm->tm_year + 1900,
142 tm->tm_mon + 1, tm->tm_mday);
143 else if (mode == DATE_ISO8601)
144 sprintf(timebuf, "%04d-%02d-%02d %02d:%02d:%02d %+05d",
145 tm->tm_year + 1900,
146 tm->tm_mon + 1,
147 tm->tm_mday,
148 tm->tm_hour, tm->tm_min, tm->tm_sec,
149 tz);
150 else if (mode == DATE_RFC2822)
151 sprintf(timebuf, "%.3s, %d %.3s %d %02d:%02d:%02d %+05d",
152 weekday_names[tm->tm_wday], tm->tm_mday,
153 month_names[tm->tm_mon], tm->tm_year + 1900,
154 tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
155 else
156 sprintf(timebuf, "%.3s %.3s %d %02d:%02d:%02d %d%c%+05d",
157 weekday_names[tm->tm_wday],
158 month_names[tm->tm_mon],
159 tm->tm_mday,
160 tm->tm_hour, tm->tm_min, tm->tm_sec,
161 tm->tm_year + 1900,
162 (mode == DATE_LOCAL) ? 0 : ' ',
163 tz);
164 return timebuf;
165 }
166
167 /*
168 * Check these. And note how it doesn't do the summer-time conversion.
169 *
170 * In my world, it's always summer, and things are probably a bit off
171 * in other ways too.
172 */
173 static const struct {
174 const char *name;
175 int offset;
176 int dst;
177 } timezone_names[] = {
178 { "IDLW", -12, 0, }, /* International Date Line West */
179 { "NT", -11, 0, }, /* Nome */
180 { "CAT", -10, 0, }, /* Central Alaska */
181 { "HST", -10, 0, }, /* Hawaii Standard */
182 { "HDT", -10, 1, }, /* Hawaii Daylight */
183 { "YST", -9, 0, }, /* Yukon Standard */
184 { "YDT", -9, 1, }, /* Yukon Daylight */
185 { "PST", -8, 0, }, /* Pacific Standard */
186 { "PDT", -8, 1, }, /* Pacific Daylight */
187 { "MST", -7, 0, }, /* Mountain Standard */
188 { "MDT", -7, 1, }, /* Mountain Daylight */
189 { "CST", -6, 0, }, /* Central Standard */
190 { "CDT", -6, 1, }, /* Central Daylight */
191 { "EST", -5, 0, }, /* Eastern Standard */
192 { "EDT", -5, 1, }, /* Eastern Daylight */
193 { "AST", -3, 0, }, /* Atlantic Standard */
194 { "ADT", -3, 1, }, /* Atlantic Daylight */
195 { "WAT", -1, 0, }, /* West Africa */
196
197 { "GMT", 0, 0, }, /* Greenwich Mean */
198 { "UTC", 0, 0, }, /* Universal (Coordinated) */
199
200 { "WET", 0, 0, }, /* Western European */
201 { "BST", 0, 1, }, /* British Summer */
202 { "CET", +1, 0, }, /* Central European */
203 { "MET", +1, 0, }, /* Middle European */
204 { "MEWT", +1, 0, }, /* Middle European Winter */
205 { "MEST", +1, 1, }, /* Middle European Summer */
206 { "CEST", +1, 1, }, /* Central European Summer */
207 { "MESZ", +1, 1, }, /* Middle European Summer */
208 { "FWT", +1, 0, }, /* French Winter */
209 { "FST", +1, 1, }, /* French Summer */
210 { "EET", +2, 0, }, /* Eastern Europe, USSR Zone 1 */
211 { "EEST", +2, 1, }, /* Eastern European Daylight */
212 { "WAST", +7, 0, }, /* West Australian Standard */
213 { "WADT", +7, 1, }, /* West Australian Daylight */
214 { "CCT", +8, 0, }, /* China Coast, USSR Zone 7 */
215 { "JST", +9, 0, }, /* Japan Standard, USSR Zone 8 */
216 { "EAST", +10, 0, }, /* Eastern Australian Standard */
217 { "EADT", +10, 1, }, /* Eastern Australian Daylight */
218 { "GST", +10, 0, }, /* Guam Standard, USSR Zone 9 */
219 { "NZT", +12, 0, }, /* New Zealand */
220 { "NZST", +12, 0, }, /* New Zealand Standard */
221 { "NZDT", +12, 1, }, /* New Zealand Daylight */
222 { "IDLE", +12, 0, }, /* International Date Line East */
223 };
224
225 static int match_string(const char *date, const char *str)
226 {
227 int i = 0;
228
229 for (i = 0; *date; date++, str++, i++) {
230 if (*date == *str)
231 continue;
232 if (toupper(*date) == toupper(*str))
233 continue;
234 if (!isalnum(*date))
235 break;
236 return 0;
237 }
238 return i;
239 }
240
241 static int skip_alpha(const char *date)
242 {
243 int i = 0;
244 do {
245 i++;
246 } while (isalpha(date[i]));
247 return i;
248 }
249
250 /*
251 * Parse month, weekday, or timezone name
252 */
253 static int match_alpha(const char *date, struct tm *tm, int *offset)
254 {
255 int i;
256
257 for (i = 0; i < 12; i++) {
258 int match = match_string(date, month_names[i]);
259 if (match >= 3) {
260 tm->tm_mon = i;
261 return match;
262 }
263 }
264
265 for (i = 0; i < 7; i++) {
266 int match = match_string(date, weekday_names[i]);
267 if (match >= 3) {
268 tm->tm_wday = i;
269 return match;
270 }
271 }
272
273 for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
274 int match = match_string(date, timezone_names[i].name);
275 if (match >= 3) {
276 int off = timezone_names[i].offset;
277
278 /* This is bogus, but we like summer */
279 off += timezone_names[i].dst;
280
281 /* Only use the tz name offset if we don't have anything better */
282 if (*offset == -1)
283 *offset = 60*off;
284
285 return match;
286 }
287 }
288
289 if (match_string(date, "PM") == 2) {
290 tm->tm_hour = (tm->tm_hour % 12) + 12;
291 return 2;
292 }
293
294 if (match_string(date, "AM") == 2) {
295 tm->tm_hour = (tm->tm_hour % 12) + 0;
296 return 2;
297 }
298
299 /* BAD CRAP */
300 return skip_alpha(date);
301 }
302
303 static int is_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
304 {
305 if (month > 0 && month < 13 && day > 0 && day < 32) {
306 struct tm check = *tm;
307 struct tm *r = (now_tm ? &check : tm);
308 time_t specified;
309
310 r->tm_mon = month - 1;
311 r->tm_mday = day;
312 if (year == -1) {
313 if (!now_tm)
314 return 1;
315 r->tm_year = now_tm->tm_year;
316 }
317 else if (year >= 1970 && year < 2100)
318 r->tm_year = year - 1900;
319 else if (year > 70 && year < 100)
320 r->tm_year = year;
321 else if (year < 38)
322 r->tm_year = year + 100;
323 else
324 return 0;
325 if (!now_tm)
326 return 1;
327
328 specified = tm_to_time_t(r);
329
330 /* Be it commit time or author time, it does not make
331 * sense to specify timestamp way into the future. Make
332 * sure it is not later than ten days from now...
333 */
334 if (now + 10*24*3600 < specified)
335 return 0;
336 tm->tm_mon = r->tm_mon;
337 tm->tm_mday = r->tm_mday;
338 if (year != -1)
339 tm->tm_year = r->tm_year;
340 return 1;
341 }
342 return 0;
343 }
344
345 static int match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
346 {
347 time_t now;
348 struct tm now_tm;
349 struct tm *refuse_future;
350 long num2, num3;
351
352 num2 = strtol(end+1, &end, 10);
353 num3 = -1;
354 if (*end == c && isdigit(end[1]))
355 num3 = strtol(end+1, &end, 10);
356
357 /* Time? Date? */
358 switch (c) {
359 case ':':
360 if (num3 < 0)
361 num3 = 0;
362 if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
363 tm->tm_hour = num;
364 tm->tm_min = num2;
365 tm->tm_sec = num3;
366 break;
367 }
368 return 0;
369
370 case '-':
371 case '/':
372 case '.':
373 now = time(NULL);
374 refuse_future = NULL;
375 if (gmtime_r(&now, &now_tm))
376 refuse_future = &now_tm;
377
378 if (num > 70) {
379 /* yyyy-mm-dd? */
380 if (is_date(num, num2, num3, refuse_future, now, tm))
381 break;
382 /* yyyy-dd-mm? */
383 if (is_date(num, num3, num2, refuse_future, now, tm))
384 break;
385 }
386 /* Our eastern European friends say dd.mm.yy[yy]
387 * is the norm there, so giving precedence to
388 * mm/dd/yy[yy] form only when separator is not '.'
389 */
390 if (c != '.' &&
391 is_date(num3, num, num2, refuse_future, now, tm))
392 break;
393 /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
394 if (is_date(num3, num2, num, refuse_future, now, tm))
395 break;
396 /* Funny European mm.dd.yy */
397 if (c == '.' &&
398 is_date(num3, num, num2, refuse_future, now, tm))
399 break;
400 return 0;
401 }
402 return end - date;
403 }
404
405 /* Have we filled in any part of the time/date yet? */
406 static inline int nodate(struct tm *tm)
407 {
408 return tm->tm_year < 0 &&
409 tm->tm_mon < 0 &&
410 tm->tm_mday < 0 &&
411 !(tm->tm_hour | tm->tm_min | tm->tm_sec);
412 }
413
414 /*
415 * We've seen a digit. Time? Year? Date?
416 */
417 static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
418 {
419 int n;
420 char *end;
421 unsigned long num;
422
423 num = strtoul(date, &end, 10);
424
425 /*
426 * Seconds since 1970? We trigger on that for any numbers with
427 * more than 8 digits. This is because we don't want to rule out
428 * numbers like 20070606 as a YYYYMMDD date.
429 */
430 if (num >= 100000000 && nodate(tm)) {
431 time_t time = num;
432 if (gmtime_r(&time, tm)) {
433 *tm_gmt = 1;
434 return end - date;
435 }
436 }
437
438 /*
439 * Check for special formats: num[-.:/]num[same]num
440 */
441 switch (*end) {
442 case ':':
443 case '.':
444 case '/':
445 case '-':
446 if (isdigit(end[1])) {
447 int match = match_multi_number(num, *end, date, end, tm);
448 if (match)
449 return match;
450 }
451 }
452
453 /*
454 * None of the special formats? Try to guess what
455 * the number meant. We use the number of digits
456 * to make a more educated guess..
457 */
458 n = 0;
459 do {
460 n++;
461 } while (isdigit(date[n]));
462
463 /* Four-digit year or a timezone? */
464 if (n == 4) {
465 if (num <= 1400 && *offset == -1) {
466 unsigned int minutes = num % 100;
467 unsigned int hours = num / 100;
468 *offset = hours*60 + minutes;
469 } else if (num > 1900 && num < 2100)
470 tm->tm_year = num - 1900;
471 return n;
472 }
473
474 /*
475 * Ignore lots of numerals. We took care of 4-digit years above.
476 * Days or months must be one or two digits.
477 */
478 if (n > 2)
479 return n;
480
481 /*
482 * NOTE! We will give precedence to day-of-month over month or
483 * year numbers in the 1-12 range. So 05 is always "mday 5",
484 * unless we already have a mday..
485 *
486 * IOW, 01 Apr 05 parses as "April 1st, 2005".
487 */
488 if (num > 0 && num < 32 && tm->tm_mday < 0) {
489 tm->tm_mday = num;
490 return n;
491 }
492
493 /* Two-digit year? */
494 if (n == 2 && tm->tm_year < 0) {
495 if (num < 10 && tm->tm_mday >= 0) {
496 tm->tm_year = num + 100;
497 return n;
498 }
499 if (num >= 70) {
500 tm->tm_year = num;
501 return n;
502 }
503 }
504
505 if (num > 0 && num < 32) {
506 tm->tm_mday = num;
507 } else if (num > 0 && num < 13) {
508 tm->tm_mon = num-1;
509 }
510
511 return n;
512 }
513
514 static int match_tz(const char *date, int *offp)
515 {
516 char *end;
517 int offset = strtoul(date+1, &end, 10);
518 int min, hour;
519 int n = end - date - 1;
520
521 min = offset % 100;
522 hour = offset / 100;
523
524 /*
525 * Don't accept any random crap.. At least 3 digits, and
526 * a valid minute. We might want to check that the minutes
527 * are divisible by 30 or something too.
528 */
529 if (min < 60 && n > 2) {
530 offset = hour*60+min;
531 if (*date == '-')
532 offset = -offset;
533
534 *offp = offset;
535 }
536 return end - date;
537 }
538
539 static int date_string(unsigned long date, int offset, char *buf, int len)
540 {
541 int sign = '+';
542
543 if (offset < 0) {
544 offset = -offset;
545 sign = '-';
546 }
547 return snprintf(buf, len, "%lu %c%02d%02d", date, sign, offset / 60, offset % 60);
548 }
549
550 /* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
551 (i.e. English) day/month names, and it doesn't work correctly with %z. */
552 int parse_date(const char *date, char *result, int maxlen)
553 {
554 struct tm tm;
555 int offset, tm_gmt;
556 time_t then;
557
558 memset(&tm, 0, sizeof(tm));
559 tm.tm_year = -1;
560 tm.tm_mon = -1;
561 tm.tm_mday = -1;
562 tm.tm_isdst = -1;
563 offset = -1;
564 tm_gmt = 0;
565
566 for (;;) {
567 int match = 0;
568 unsigned char c = *date;
569
570 /* Stop at end of string or newline */
571 if (!c || c == '\n')
572 break;
573
574 if (isalpha(c))
575 match = match_alpha(date, &tm, &offset);
576 else if (isdigit(c))
577 match = match_digit(date, &tm, &offset, &tm_gmt);
578 else if ((c == '-' || c == '+') && isdigit(date[1]))
579 match = match_tz(date, &offset);
580
581 if (!match) {
582 /* BAD CRAP */
583 match = 1;
584 }
585
586 date += match;
587 }
588
589 /* mktime uses local timezone */
590 then = tm_to_time_t(&tm);
591 if (offset == -1)
592 offset = (then - mktime(&tm)) / 60;
593
594 if (then == -1)
595 return -1;
596
597 if (!tm_gmt)
598 then -= offset * 60;
599 return date_string(then, offset, result, maxlen);
600 }
601
602 enum date_mode parse_date_format(const char *format)
603 {
604 if (!strcmp(format, "relative"))
605 return DATE_RELATIVE;
606 else if (!strcmp(format, "iso8601") ||
607 !strcmp(format, "iso"))
608 return DATE_ISO8601;
609 else if (!strcmp(format, "rfc2822") ||
610 !strcmp(format, "rfc"))
611 return DATE_RFC2822;
612 else if (!strcmp(format, "short"))
613 return DATE_SHORT;
614 else if (!strcmp(format, "local"))
615 return DATE_LOCAL;
616 else if (!strcmp(format, "default"))
617 return DATE_NORMAL;
618 else
619 die("unknown date format %s", format);
620 }
621
622 void datestamp(char *buf, int bufsize)
623 {
624 time_t now;
625 int offset;
626
627 time(&now);
628
629 offset = tm_to_time_t(localtime(&now)) - now;
630 offset /= 60;
631
632 date_string(now, offset, buf, bufsize);
633 }
634
635 static void update_tm(struct tm *tm, unsigned long sec)
636 {
637 time_t n = mktime(tm) - sec;
638 localtime_r(&n, tm);
639 }
640
641 static void date_yesterday(struct tm *tm, int *num)
642 {
643 update_tm(tm, 24*60*60);
644 }
645
646 static void date_time(struct tm *tm, int hour)
647 {
648 if (tm->tm_hour < hour)
649 date_yesterday(tm, NULL);
650 tm->tm_hour = hour;
651 tm->tm_min = 0;
652 tm->tm_sec = 0;
653 }
654
655 static void date_midnight(struct tm *tm, int *num)
656 {
657 date_time(tm, 0);
658 }
659
660 static void date_noon(struct tm *tm, int *num)
661 {
662 date_time(tm, 12);
663 }
664
665 static void date_tea(struct tm *tm, int *num)
666 {
667 date_time(tm, 17);
668 }
669
670 static void date_pm(struct tm *tm, int *num)
671 {
672 int hour, n = *num;
673 *num = 0;
674
675 hour = tm->tm_hour;
676 if (n) {
677 hour = n;
678 tm->tm_min = 0;
679 tm->tm_sec = 0;
680 }
681 tm->tm_hour = (hour % 12) + 12;
682 }
683
684 static void date_am(struct tm *tm, int *num)
685 {
686 int hour, n = *num;
687 *num = 0;
688
689 hour = tm->tm_hour;
690 if (n) {
691 hour = n;
692 tm->tm_min = 0;
693 tm->tm_sec = 0;
694 }
695 tm->tm_hour = (hour % 12);
696 }
697
698 static void date_never(struct tm *tm, int *num)
699 {
700 time_t n = 0;
701 localtime_r(&n, tm);
702 }
703
704 static const struct special {
705 const char *name;
706 void (*fn)(struct tm *, int *);
707 } special[] = {
708 { "yesterday", date_yesterday },
709 { "noon", date_noon },
710 { "midnight", date_midnight },
711 { "tea", date_tea },
712 { "PM", date_pm },
713 { "AM", date_am },
714 { "never", date_never },
715 { NULL }
716 };
717
718 static const char *number_name[] = {
719 "zero", "one", "two", "three", "four",
720 "five", "six", "seven", "eight", "nine", "ten",
721 };
722
723 static const struct typelen {
724 const char *type;
725 int length;
726 } typelen[] = {
727 { "seconds", 1 },
728 { "minutes", 60 },
729 { "hours", 60*60 },
730 { "days", 24*60*60 },
731 { "weeks", 7*24*60*60 },
732 { NULL }
733 };
734
735 static const char *approxidate_alpha(const char *date, struct tm *tm, int *num)
736 {
737 const struct typelen *tl;
738 const struct special *s;
739 const char *end = date;
740 int i;
741
742 while (isalpha(*++end));
743 ;
744
745 for (i = 0; i < 12; i++) {
746 int match = match_string(date, month_names[i]);
747 if (match >= 3) {
748 tm->tm_mon = i;
749 return end;
750 }
751 }
752
753 for (s = special; s->name; s++) {
754 int len = strlen(s->name);
755 if (match_string(date, s->name) == len) {
756 s->fn(tm, num);
757 return end;
758 }
759 }
760
761 if (!*num) {
762 for (i = 1; i < 11; i++) {
763 int len = strlen(number_name[i]);
764 if (match_string(date, number_name[i]) == len) {
765 *num = i;
766 return end;
767 }
768 }
769 if (match_string(date, "last") == 4)
770 *num = 1;
771 return end;
772 }
773
774 tl = typelen;
775 while (tl->type) {
776 int len = strlen(tl->type);
777 if (match_string(date, tl->type) >= len-1) {
778 update_tm(tm, tl->length * *num);
779 *num = 0;
780 return end;
781 }
782 tl++;
783 }
784
785 for (i = 0; i < 7; i++) {
786 int match = match_string(date, weekday_names[i]);
787 if (match >= 3) {
788 int diff, n = *num -1;
789 *num = 0;
790
791 diff = tm->tm_wday - i;
792 if (diff <= 0)
793 n++;
794 diff += 7*n;
795
796 update_tm(tm, diff * 24 * 60 * 60);
797 return end;
798 }
799 }
800
801 if (match_string(date, "months") >= 5) {
802 int n = tm->tm_mon - *num;
803 *num = 0;
804 while (n < 0) {
805 n += 12;
806 tm->tm_year--;
807 }
808 tm->tm_mon = n;
809 return end;
810 }
811
812 if (match_string(date, "years") >= 4) {
813 tm->tm_year -= *num;
814 *num = 0;
815 return end;
816 }
817
818 return end;
819 }
820
821 static const char *approxidate_digit(const char *date, struct tm *tm, int *num)
822 {
823 char *end;
824 unsigned long number = strtoul(date, &end, 10);
825
826 switch (*end) {
827 case ':':
828 case '.':
829 case '/':
830 case '-':
831 if (isdigit(end[1])) {
832 int match = match_multi_number(number, *end, date, end, tm);
833 if (match)
834 return date + match;
835 }
836 }
837
838 /* Accept zero-padding only for small numbers ("Dec 02", never "Dec 0002") */
839 if (date[0] != '0' || end - date <= 2)
840 *num = number;
841 return end;
842 }
843
844 unsigned long approxidate(const char *date)
845 {
846 int number = 0;
847 struct tm tm, now;
848 struct timeval tv;
849 char buffer[50];
850
851 if (parse_date(date, buffer, sizeof(buffer)) > 0)
852 return strtoul(buffer, NULL, 10);
853
854 gettimeofday(&tv, NULL);
855 localtime_r(&tv.tv_sec, &tm);
856 now = tm;
857 for (;;) {
858 unsigned char c = *date;
859 if (!c)
860 break;
861 date++;
862 if (isdigit(c)) {
863 date = approxidate_digit(date-1, &tm, &number);
864 continue;
865 }
866 if (isalpha(c))
867 date = approxidate_alpha(date-1, &tm, &number);
868 }
869 if (number > 0 && number < 32)
870 tm.tm_mday = number;
871 if (tm.tm_mon > now.tm_mon && tm.tm_year == now.tm_year)
872 tm.tm_year--;
873 return mktime(&tm);
874 }
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