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some doc updates
[git/peff.git] / date.c
blob7acb8cbd91bb1491931326ade1905d9c6f7bfdf5
1 /*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
6
7 #include "cache.h"
8
9 static time_t my_mktime(struct tm *tm)
10 {
11 static const int mdays[] = {
12 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
13 };
14 int year = tm->tm_year - 70;
15 int month = tm->tm_mon;
16 int day = tm->tm_mday;
17
18 if (year < 0 || year > 129) /* algo only works for 1970-2099 */
19 return -1;
20 if (month < 0 || month > 11) /* array bounds */
21 return -1;
22 if (month < 2 || (year + 2) % 4)
23 day--;
24 return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
25 tm->tm_hour * 60*60 + tm->tm_min * 60 + tm->tm_sec;
26 }
27
28 static const char *month_names[] = {
29 "January", "February", "March", "April", "May", "June",
30 "July", "August", "September", "October", "November", "December"
31 };
32
33 static const char *weekday_names[] = {
34 "Sundays", "Mondays", "Tuesdays", "Wednesdays", "Thursdays", "Fridays", "Saturdays"
35 };
36
37 static time_t gm_time_t(unsigned long time, int tz)
38 {
39 int minutes;
40
41 minutes = tz < 0 ? -tz : tz;
42 minutes = (minutes / 100)*60 + (minutes % 100);
43 minutes = tz < 0 ? -minutes : minutes;
44 return time + minutes * 60;
45 }
46
47 /*
48 * The "tz" thing is passed in as this strange "decimal parse of tz"
49 * thing, which means that tz -0100 is passed in as the integer -100,
50 * even though it means "sixty minutes off"
51 */
52 static struct tm *time_to_tm(unsigned long time, int tz)
53 {
54 time_t t = gm_time_t(time, tz);
55 return gmtime(&t);
56 }
57
58 const char *show_date(unsigned long time, int tz, int relative)
59 {
60 struct tm *tm;
61 static char timebuf[200];
62
63 if (relative) {
64 unsigned long diff;
65 time_t t = gm_time_t(time, tz);
66 struct timeval now;
67 gettimeofday(&now, NULL);
68 if (now.tv_sec < t)
69 return "in the future";
70 diff = now.tv_sec - t;
71 if (diff < 90) {
72 snprintf(timebuf, sizeof(timebuf), "%lu seconds ago", diff);
73 return timebuf;
74 }
75 /* Turn it into minutes */
76 diff = (diff + 30) / 60;
77 if (diff < 90) {
78 snprintf(timebuf, sizeof(timebuf), "%lu minutes ago", diff);
79 return timebuf;
80 }
81 /* Turn it into hours */
82 diff = (diff + 30) / 60;
83 if (diff < 36) {
84 snprintf(timebuf, sizeof(timebuf), "%lu hours ago", diff);
85 return timebuf;
86 }
87 /* We deal with number of days from here on */
88 diff = (diff + 12) / 24;
89 if (diff < 14) {
90 snprintf(timebuf, sizeof(timebuf), "%lu days ago", diff);
91 return timebuf;
92 }
93 /* Say weeks for the past 10 weeks or so */
94 if (diff < 70) {
95 snprintf(timebuf, sizeof(timebuf), "%lu weeks ago", (diff + 3) / 7);
96 return timebuf;
97 }
98 /* Say months for the past 12 months or so */
99 if (diff < 360) {
100 snprintf(timebuf, sizeof(timebuf), "%lu months ago", (diff + 15) / 30);
101 return timebuf;
102 }
103 /* Else fall back on absolute format.. */
104 }
105
106 tm = time_to_tm(time, tz);
107 if (!tm)
108 return NULL;
109 sprintf(timebuf, "%.3s %.3s %d %02d:%02d:%02d %d %+05d",
110 weekday_names[tm->tm_wday],
111 month_names[tm->tm_mon],
112 tm->tm_mday,
113 tm->tm_hour, tm->tm_min, tm->tm_sec,
114 tm->tm_year + 1900, tz);
115 return timebuf;
116 }
117
118 const char *show_rfc2822_date(unsigned long time, int tz)
119 {
120 struct tm *tm;
121 static char timebuf[200];
122
123 tm = time_to_tm(time, tz);
124 if (!tm)
125 return NULL;
126 sprintf(timebuf, "%.3s, %d %.3s %d %02d:%02d:%02d %+05d",
127 weekday_names[tm->tm_wday], tm->tm_mday,
128 month_names[tm->tm_mon], tm->tm_year + 1900,
129 tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
130 return timebuf;
131 }
132
133 /*
134 * Check these. And note how it doesn't do the summer-time conversion.
135 *
136 * In my world, it's always summer, and things are probably a bit off
137 * in other ways too.
138 */
139 static const struct {
140 const char *name;
141 int offset;
142 int dst;
143 } timezone_names[] = {
144 { "IDLW", -12, 0, }, /* International Date Line West */
145 { "NT", -11, 0, }, /* Nome */
146 { "CAT", -10, 0, }, /* Central Alaska */
147 { "HST", -10, 0, }, /* Hawaii Standard */
148 { "HDT", -10, 1, }, /* Hawaii Daylight */
149 { "YST", -9, 0, }, /* Yukon Standard */
150 { "YDT", -9, 1, }, /* Yukon Daylight */
151 { "PST", -8, 0, }, /* Pacific Standard */
152 { "PDT", -8, 1, }, /* Pacific Daylight */
153 { "MST", -7, 0, }, /* Mountain Standard */
154 { "MDT", -7, 1, }, /* Mountain Daylight */
155 { "CST", -6, 0, }, /* Central Standard */
156 { "CDT", -6, 1, }, /* Central Daylight */
157 { "EST", -5, 0, }, /* Eastern Standard */
158 { "EDT", -5, 1, }, /* Eastern Daylight */
159 { "AST", -3, 0, }, /* Atlantic Standard */
160 { "ADT", -3, 1, }, /* Atlantic Daylight */
161 { "WAT", -1, 0, }, /* West Africa */
162
163 { "GMT", 0, 0, }, /* Greenwich Mean */
164 { "UTC", 0, 0, }, /* Universal (Coordinated) */
165
166 { "WET", 0, 0, }, /* Western European */
167 { "BST", 0, 1, }, /* British Summer */
168 { "CET", +1, 0, }, /* Central European */
169 { "MET", +1, 0, }, /* Middle European */
170 { "MEWT", +1, 0, }, /* Middle European Winter */
171 { "MEST", +1, 1, }, /* Middle European Summer */
172 { "CEST", +1, 1, }, /* Central European Summer */
173 { "MESZ", +1, 1, }, /* Middle European Summer */
174 { "FWT", +1, 0, }, /* French Winter */
175 { "FST", +1, 1, }, /* French Summer */
176 { "EET", +2, 0, }, /* Eastern Europe, USSR Zone 1 */
177 { "EEST", +2, 1, }, /* Eastern European Daylight */
178 { "WAST", +7, 0, }, /* West Australian Standard */
179 { "WADT", +7, 1, }, /* West Australian Daylight */
180 { "CCT", +8, 0, }, /* China Coast, USSR Zone 7 */
181 { "JST", +9, 0, }, /* Japan Standard, USSR Zone 8 */
182 { "EAST", +10, 0, }, /* Eastern Australian Standard */
183 { "EADT", +10, 1, }, /* Eastern Australian Daylight */
184 { "GST", +10, 0, }, /* Guam Standard, USSR Zone 9 */
185 { "NZT", +11, 0, }, /* New Zealand */
186 { "NZST", +11, 0, }, /* New Zealand Standard */
187 { "NZDT", +11, 1, }, /* New Zealand Daylight */
188 { "IDLE", +12, 0, }, /* International Date Line East */
189 };
190
191 static int match_string(const char *date, const char *str)
192 {
193 int i = 0;
194
195 for (i = 0; *date; date++, str++, i++) {
196 if (*date == *str)
197 continue;
198 if (toupper(*date) == toupper(*str))
199 continue;
200 if (!isalnum(*date))
201 break;
202 return 0;
203 }
204 return i;
205 }
206
207 static int skip_alpha(const char *date)
208 {
209 int i = 0;
210 do {
211 i++;
212 } while (isalpha(date[i]));
213 return i;
214 }
215
216 /*
217 * Parse month, weekday, or timezone name
218 */
219 static int match_alpha(const char *date, struct tm *tm, int *offset)
220 {
221 int i;
222
223 for (i = 0; i < 12; i++) {
224 int match = match_string(date, month_names[i]);
225 if (match >= 3) {
226 tm->tm_mon = i;
227 return match;
228 }
229 }
230
231 for (i = 0; i < 7; i++) {
232 int match = match_string(date, weekday_names[i]);
233 if (match >= 3) {
234 tm->tm_wday = i;
235 return match;
236 }
237 }
238
239 for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
240 int match = match_string(date, timezone_names[i].name);
241 if (match >= 3) {
242 int off = timezone_names[i].offset;
243
244 /* This is bogus, but we like summer */
245 off += timezone_names[i].dst;
246
247 /* Only use the tz name offset if we don't have anything better */
248 if (*offset == -1)
249 *offset = 60*off;
250
251 return match;
252 }
253 }
254
255 if (match_string(date, "PM") == 2) {
256 tm->tm_hour = (tm->tm_hour % 12) + 12;
257 return 2;
258 }
259
260 if (match_string(date, "AM") == 2) {
261 tm->tm_hour = (tm->tm_hour % 12) + 0;
262 return 2;
263 }
264
265 /* BAD CRAP */
266 return skip_alpha(date);
267 }
268
269 static int is_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
270 {
271 if (month > 0 && month < 13 && day > 0 && day < 32) {
272 struct tm check = *tm;
273 struct tm *r = (now_tm ? &check : tm);
274 time_t specified;
275
276 r->tm_mon = month - 1;
277 r->tm_mday = day;
278 if (year == -1) {
279 if (!now_tm)
280 return 1;
281 r->tm_year = now_tm->tm_year;
282 }
283 else if (year >= 1970 && year < 2100)
284 r->tm_year = year - 1900;
285 else if (year > 70 && year < 100)
286 r->tm_year = year;
287 else if (year < 38)
288 r->tm_year = year + 100;
289 else
290 return 0;
291 if (!now_tm)
292 return 1;
293
294 specified = my_mktime(r);
295
296 /* Be it commit time or author time, it does not make
297 * sense to specify timestamp way into the future. Make
298 * sure it is not later than ten days from now...
299 */
300 if (now + 10*24*3600 < specified)
301 return 0;
302 tm->tm_mon = r->tm_mon;
303 tm->tm_mday = r->tm_mday;
304 if (year != -1)
305 tm->tm_year = r->tm_year;
306 return 1;
307 }
308 return 0;
309 }
310
311 static int match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
312 {
313 time_t now;
314 struct tm now_tm;
315 struct tm *refuse_future;
316 long num2, num3;
317
318 num2 = strtol(end+1, &end, 10);
319 num3 = -1;
320 if (*end == c && isdigit(end[1]))
321 num3 = strtol(end+1, &end, 10);
322
323 /* Time? Date? */
324 switch (c) {
325 case ':':
326 if (num3 < 0)
327 num3 = 0;
328 if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
329 tm->tm_hour = num;
330 tm->tm_min = num2;
331 tm->tm_sec = num3;
332 break;
333 }
334 return 0;
335
336 case '-':
337 case '/':
338 case '.':
339 now = time(NULL);
340 refuse_future = NULL;
341 if (gmtime_r(&now, &now_tm))
342 refuse_future = &now_tm;
343
344 if (num > 70) {
345 /* yyyy-mm-dd? */
346 if (is_date(num, num2, num3, refuse_future, now, tm))
347 break;
348 /* yyyy-dd-mm? */
349 if (is_date(num, num3, num2, refuse_future, now, tm))
350 break;
351 }
352 /* Our eastern European friends say dd.mm.yy[yy]
353 * is the norm there, so giving precedence to
354 * mm/dd/yy[yy] form only when separator is not '.'
355 */
356 if (c != '.' &&
357 is_date(num3, num, num2, refuse_future, now, tm))
358 break;
359 /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
360 if (is_date(num3, num2, num, refuse_future, now, tm))
361 break;
362 /* Funny European mm.dd.yy */
363 if (c == '.' &&
364 is_date(num3, num, num2, refuse_future, now, tm))
365 break;
366 return 0;
367 }
368 return end - date;
369 }
370
371 /*
372 * We've seen a digit. Time? Year? Date?
373 */
374 static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
375 {
376 int n;
377 char *end;
378 unsigned long num;
379
380 num = strtoul(date, &end, 10);
381
382 /*
383 * Seconds since 1970? We trigger on that for anything after Jan 1, 2000
384 */
385 if (num > 946684800) {
386 time_t time = num;
387 if (gmtime_r(&time, tm)) {
388 *tm_gmt = 1;
389 return end - date;
390 }
391 }
392
393 /*
394 * Check for special formats: num[-.:/]num[same]num
395 */
396 switch (*end) {
397 case ':':
398 case '.':
399 case '/':
400 case '-':
401 if (isdigit(end[1])) {
402 int match = match_multi_number(num, *end, date, end, tm);
403 if (match)
404 return match;
405 }
406 }
407
408 /*
409 * None of the special formats? Try to guess what
410 * the number meant. We use the number of digits
411 * to make a more educated guess..
412 */
413 n = 0;
414 do {
415 n++;
416 } while (isdigit(date[n]));
417
418 /* Four-digit year or a timezone? */
419 if (n == 4) {
420 if (num <= 1400 && *offset == -1) {
421 unsigned int minutes = num % 100;
422 unsigned int hours = num / 100;
423 *offset = hours*60 + minutes;
424 } else if (num > 1900 && num < 2100)
425 tm->tm_year = num - 1900;
426 return n;
427 }
428
429 /*
430 * NOTE! We will give precedence to day-of-month over month or
431 * year numbers in the 1-12 range. So 05 is always "mday 5",
432 * unless we already have a mday..
433 *
434 * IOW, 01 Apr 05 parses as "April 1st, 2005".
435 */
436 if (num > 0 && num < 32 && tm->tm_mday < 0) {
437 tm->tm_mday = num;
438 return n;
439 }
440
441 /* Two-digit year? */
442 if (n == 2 && tm->tm_year < 0) {
443 if (num < 10 && tm->tm_mday >= 0) {
444 tm->tm_year = num + 100;
445 return n;
446 }
447 if (num >= 70) {
448 tm->tm_year = num;
449 return n;
450 }
451 }
452
453 if (num > 0 && num < 32) {
454 tm->tm_mday = num;
455 } else if (num > 1900) {
456 tm->tm_year = num - 1900;
457 } else if (num > 70) {
458 tm->tm_year = num;
459 } else if (num > 0 && num < 13) {
460 tm->tm_mon = num-1;
461 }
462
463 return n;
464 }
465
466 static int match_tz(const char *date, int *offp)
467 {
468 char *end;
469 int offset = strtoul(date+1, &end, 10);
470 int min, hour;
471 int n = end - date - 1;
472
473 min = offset % 100;
474 hour = offset / 100;
475
476 /*
477 * Don't accept any random crap.. At least 3 digits, and
478 * a valid minute. We might want to check that the minutes
479 * are divisible by 30 or something too.
480 */
481 if (min < 60 && n > 2) {
482 offset = hour*60+min;
483 if (*date == '-')
484 offset = -offset;
485
486 *offp = offset;
487 }
488 return end - date;
489 }
490
491 static int date_string(unsigned long date, int offset, char *buf, int len)
492 {
493 int sign = '+';
494
495 if (offset < 0) {
496 offset = -offset;
497 sign = '-';
498 }
499 return snprintf(buf, len, "%lu %c%02d%02d", date, sign, offset / 60, offset % 60);
500 }
501
502 /* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
503 (i.e. English) day/month names, and it doesn't work correctly with %z. */
504 int parse_date(const char *date, char *result, int maxlen)
505 {
506 struct tm tm;
507 int offset, tm_gmt;
508 time_t then;
509
510 memset(&tm, 0, sizeof(tm));
511 tm.tm_year = -1;
512 tm.tm_mon = -1;
513 tm.tm_mday = -1;
514 tm.tm_isdst = -1;
515 offset = -1;
516 tm_gmt = 0;
517
518 for (;;) {
519 int match = 0;
520 unsigned char c = *date;
521
522 /* Stop at end of string or newline */
523 if (!c || c == '\n')
524 break;
525
526 if (isalpha(c))
527 match = match_alpha(date, &tm, &offset);
528 else if (isdigit(c))
529 match = match_digit(date, &tm, &offset, &tm_gmt);
530 else if ((c == '-' || c == '+') && isdigit(date[1]))
531 match = match_tz(date, &offset);
532
533 if (!match) {
534 /* BAD CRAP */
535 match = 1;
536 }
537
538 date += match;
539 }
540
541 /* mktime uses local timezone */
542 then = my_mktime(&tm);
543 if (offset == -1)
544 offset = (then - mktime(&tm)) / 60;
545
546 if (then == -1)
547 return -1;
548
549 if (!tm_gmt)
550 then -= offset * 60;
551 return date_string(then, offset, result, maxlen);
552 }
553
554 void datestamp(char *buf, int bufsize)
555 {
556 time_t now;
557 int offset;
558
559 time(&now);
560
561 offset = my_mktime(localtime(&now)) - now;
562 offset /= 60;
563
564 date_string(now, offset, buf, bufsize);
565 }
566
567 static void update_tm(struct tm *tm, unsigned long sec)
568 {
569 time_t n = mktime(tm) - sec;
570 localtime_r(&n, tm);
571 }
572
573 static void date_yesterday(struct tm *tm, int *num)
574 {
575 update_tm(tm, 24*60*60);
576 }
577
578 static void date_time(struct tm *tm, int hour)
579 {
580 if (tm->tm_hour < hour)
581 date_yesterday(tm, NULL);
582 tm->tm_hour = hour;
583 tm->tm_min = 0;
584 tm->tm_sec = 0;
585 }
586
587 static void date_midnight(struct tm *tm, int *num)
588 {
589 date_time(tm, 0);
590 }
591
592 static void date_noon(struct tm *tm, int *num)
593 {
594 date_time(tm, 12);
595 }
596
597 static void date_tea(struct tm *tm, int *num)
598 {
599 date_time(tm, 17);
600 }
601
602 static void date_pm(struct tm *tm, int *num)
603 {
604 int hour, n = *num;
605 *num = 0;
606
607 hour = tm->tm_hour;
608 if (n) {
609 hour = n;
610 tm->tm_min = 0;
611 tm->tm_sec = 0;
612 }
613 tm->tm_hour = (hour % 12) + 12;
614 }
615
616 static void date_am(struct tm *tm, int *num)
617 {
618 int hour, n = *num;
619 *num = 0;
620
621 hour = tm->tm_hour;
622 if (n) {
623 hour = n;
624 tm->tm_min = 0;
625 tm->tm_sec = 0;
626 }
627 tm->tm_hour = (hour % 12);
628 }
629
630 static const struct special {
631 const char *name;
632 void (*fn)(struct tm *, int *);
633 } special[] = {
634 { "yesterday", date_yesterday },
635 { "noon", date_noon },
636 { "midnight", date_midnight },
637 { "tea", date_tea },
638 { "PM", date_pm },
639 { "AM", date_am },
640 { NULL }
641 };
642
643 static const char *number_name[] = {
644 "zero", "one", "two", "three", "four",
645 "five", "six", "seven", "eight", "nine", "ten",
646 };
647
648 static const struct typelen {
649 const char *type;
650 int length;
651 } typelen[] = {
652 { "seconds", 1 },
653 { "minutes", 60 },
654 { "hours", 60*60 },
655 { "days", 24*60*60 },
656 { "weeks", 7*24*60*60 },
657 { NULL }
658 };
659
660 static const char *approxidate_alpha(const char *date, struct tm *tm, int *num)
661 {
662 const struct typelen *tl;
663 const struct special *s;
664 const char *end = date;
665 int i;
666
667 while (isalpha(*++end));
668 ;
669
670 for (i = 0; i < 12; i++) {
671 int match = match_string(date, month_names[i]);
672 if (match >= 3) {
673 tm->tm_mon = i;
674 return end;
675 }
676 }
677
678 for (s = special; s->name; s++) {
679 int len = strlen(s->name);
680 if (match_string(date, s->name) == len) {
681 s->fn(tm, num);
682 return end;
683 }
684 }
685
686 if (!*num) {
687 for (i = 1; i < 11; i++) {
688 int len = strlen(number_name[i]);
689 if (match_string(date, number_name[i]) == len) {
690 *num = i;
691 return end;
692 }
693 }
694 if (match_string(date, "last") == 4)
695 *num = 1;
696 return end;
697 }
698
699 tl = typelen;
700 while (tl->type) {
701 int len = strlen(tl->type);
702 if (match_string(date, tl->type) >= len-1) {
703 update_tm(tm, tl->length * *num);
704 *num = 0;
705 return end;
706 }
707 tl++;
708 }
709
710 for (i = 0; i < 7; i++) {
711 int match = match_string(date, weekday_names[i]);
712 if (match >= 3) {
713 int diff, n = *num -1;
714 *num = 0;
715
716 diff = tm->tm_wday - i;
717 if (diff <= 0)
718 n++;
719 diff += 7*n;
720
721 update_tm(tm, diff * 24 * 60 * 60);
722 return end;
723 }
724 }
725
726 if (match_string(date, "months") >= 5) {
727 int n = tm->tm_mon - *num;
728 *num = 0;
729 while (n < 0) {
730 n += 12;
731 tm->tm_year--;
732 }
733 tm->tm_mon = n;
734 return end;
735 }
736
737 if (match_string(date, "years") >= 4) {
738 tm->tm_year -= *num;
739 *num = 0;
740 return end;
741 }
742
743 return end;
744 }
745
746 static const char *approxidate_digit(const char *date, struct tm *tm, int *num)
747 {
748 char *end;
749 unsigned long number = strtoul(date, &end, 10);
750
751 switch (*end) {
752 case ':':
753 case '.':
754 case '/':
755 case '-':
756 if (isdigit(end[1])) {
757 int match = match_multi_number(number, *end, date, end, tm);
758 if (match)
759 return date + match;
760 }
761 }
762
763 *num = number;
764 return end;
765 }
766
767 unsigned long approxidate(const char *date)
768 {
769 int number = 0;
770 struct tm tm, now;
771 struct timeval tv;
772 char buffer[50];
773
774 if (parse_date(date, buffer, sizeof(buffer)) > 0)
775 return strtoul(buffer, NULL, 10);
776
777 gettimeofday(&tv, NULL);
778 localtime_r(&tv.tv_sec, &tm);
779 now = tm;
780 for (;;) {
781 unsigned char c = *date;
782 if (!c)
783 break;
784 date++;
785 if (isdigit(c)) {
786 date = approxidate_digit(date-1, &tm, &number);
787 continue;
788 }
789 if (isalpha(c))
790 date = approxidate_alpha(date-1, &tm, &number);
791 }
792 if (number > 0 && number < 32)
793 tm.tm_mday = number;
794 if (tm.tm_mon > now.tm_mon && tm.tm_year == now.tm_year)
795 tm.tm_year--;
796 return mktime(&tm);
797 }
peff's git enhancements