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git-blame.el: Autoupdate while editing
[tgit.git] / date.c
blob542c004c2e8d2a9f731a1f303cc3393d88f5a6e8
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 struct timeval now;
66 gettimeofday(&now, NULL);
67 if (now.tv_sec < time)
68 return "in the future";
69 diff = now.tv_sec - time;
70 if (diff < 90) {
71 snprintf(timebuf, sizeof(timebuf), "%lu seconds ago", diff);
72 return timebuf;
73 }
74 /* Turn it into minutes */
75 diff = (diff + 30) / 60;
76 if (diff < 90) {
77 snprintf(timebuf, sizeof(timebuf), "%lu minutes ago", diff);
78 return timebuf;
79 }
80 /* Turn it into hours */
81 diff = (diff + 30) / 60;
82 if (diff < 36) {
83 snprintf(timebuf, sizeof(timebuf), "%lu hours ago", diff);
84 return timebuf;
85 }
86 /* We deal with number of days from here on */
87 diff = (diff + 12) / 24;
88 if (diff < 14) {
89 snprintf(timebuf, sizeof(timebuf), "%lu days ago", diff);
90 return timebuf;
91 }
92 /* Say weeks for the past 10 weeks or so */
93 if (diff < 70) {
94 snprintf(timebuf, sizeof(timebuf), "%lu weeks ago", (diff + 3) / 7);
95 return timebuf;
96 }
97 /* Say months for the past 12 months or so */
98 if (diff < 360) {
99 snprintf(timebuf, sizeof(timebuf), "%lu months ago", (diff + 15) / 30);
100 return timebuf;
101 }
102 /* Else fall back on absolute format.. */
103 }
104
105 tm = time_to_tm(time, tz);
106 if (!tm)
107 return NULL;
108 sprintf(timebuf, "%.3s %.3s %d %02d:%02d:%02d %d %+05d",
109 weekday_names[tm->tm_wday],
110 month_names[tm->tm_mon],
111 tm->tm_mday,
112 tm->tm_hour, tm->tm_min, tm->tm_sec,
113 tm->tm_year + 1900, tz);
114 return timebuf;
115 }
116
117 const char *show_rfc2822_date(unsigned long time, int tz)
118 {
119 struct tm *tm;
120 static char timebuf[200];
121
122 tm = time_to_tm(time, tz);
123 if (!tm)
124 return NULL;
125 sprintf(timebuf, "%.3s, %d %.3s %d %02d:%02d:%02d %+05d",
126 weekday_names[tm->tm_wday], tm->tm_mday,
127 month_names[tm->tm_mon], tm->tm_year + 1900,
128 tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
129 return timebuf;
130 }
131
132 /*
133 * Check these. And note how it doesn't do the summer-time conversion.
134 *
135 * In my world, it's always summer, and things are probably a bit off
136 * in other ways too.
137 */
138 static const struct {
139 const char *name;
140 int offset;
141 int dst;
142 } timezone_names[] = {
143 { "IDLW", -12, 0, }, /* International Date Line West */
144 { "NT", -11, 0, }, /* Nome */
145 { "CAT", -10, 0, }, /* Central Alaska */
146 { "HST", -10, 0, }, /* Hawaii Standard */
147 { "HDT", -10, 1, }, /* Hawaii Daylight */
148 { "YST", -9, 0, }, /* Yukon Standard */
149 { "YDT", -9, 1, }, /* Yukon Daylight */
150 { "PST", -8, 0, }, /* Pacific Standard */
151 { "PDT", -8, 1, }, /* Pacific Daylight */
152 { "MST", -7, 0, }, /* Mountain Standard */
153 { "MDT", -7, 1, }, /* Mountain Daylight */
154 { "CST", -6, 0, }, /* Central Standard */
155 { "CDT", -6, 1, }, /* Central Daylight */
156 { "EST", -5, 0, }, /* Eastern Standard */
157 { "EDT", -5, 1, }, /* Eastern Daylight */
158 { "AST", -3, 0, }, /* Atlantic Standard */
159 { "ADT", -3, 1, }, /* Atlantic Daylight */
160 { "WAT", -1, 0, }, /* West Africa */
161
162 { "GMT", 0, 0, }, /* Greenwich Mean */
163 { "UTC", 0, 0, }, /* Universal (Coordinated) */
164
165 { "WET", 0, 0, }, /* Western European */
166 { "BST", 0, 1, }, /* British Summer */
167 { "CET", +1, 0, }, /* Central European */
168 { "MET", +1, 0, }, /* Middle European */
169 { "MEWT", +1, 0, }, /* Middle European Winter */
170 { "MEST", +1, 1, }, /* Middle European Summer */
171 { "CEST", +1, 1, }, /* Central European Summer */
172 { "MESZ", +1, 1, }, /* Middle European Summer */
173 { "FWT", +1, 0, }, /* French Winter */
174 { "FST", +1, 1, }, /* French Summer */
175 { "EET", +2, 0, }, /* Eastern Europe, USSR Zone 1 */
176 { "EEST", +2, 1, }, /* Eastern European Daylight */
177 { "WAST", +7, 0, }, /* West Australian Standard */
178 { "WADT", +7, 1, }, /* West Australian Daylight */
179 { "CCT", +8, 0, }, /* China Coast, USSR Zone 7 */
180 { "JST", +9, 0, }, /* Japan Standard, USSR Zone 8 */
181 { "EAST", +10, 0, }, /* Eastern Australian Standard */
182 { "EADT", +10, 1, }, /* Eastern Australian Daylight */
183 { "GST", +10, 0, }, /* Guam Standard, USSR Zone 9 */
184 { "NZT", +11, 0, }, /* New Zealand */
185 { "NZST", +11, 0, }, /* New Zealand Standard */
186 { "NZDT", +11, 1, }, /* New Zealand Daylight */
187 { "IDLE", +12, 0, }, /* International Date Line East */
188 };
189
190 static int match_string(const char *date, const char *str)
191 {
192 int i = 0;
193
194 for (i = 0; *date; date++, str++, i++) {
195 if (*date == *str)
196 continue;
197 if (toupper(*date) == toupper(*str))
198 continue;
199 if (!isalnum(*date))
200 break;
201 return 0;
202 }
203 return i;
204 }
205
206 static int skip_alpha(const char *date)
207 {
208 int i = 0;
209 do {
210 i++;
211 } while (isalpha(date[i]));
212 return i;
213 }
214
215 /*
216 * Parse month, weekday, or timezone name
217 */
218 static int match_alpha(const char *date, struct tm *tm, int *offset)
219 {
220 int i;
221
222 for (i = 0; i < 12; i++) {
223 int match = match_string(date, month_names[i]);
224 if (match >= 3) {
225 tm->tm_mon = i;
226 return match;
227 }
228 }
229
230 for (i = 0; i < 7; i++) {
231 int match = match_string(date, weekday_names[i]);
232 if (match >= 3) {
233 tm->tm_wday = i;
234 return match;
235 }
236 }
237
238 for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
239 int match = match_string(date, timezone_names[i].name);
240 if (match >= 3) {
241 int off = timezone_names[i].offset;
242
243 /* This is bogus, but we like summer */
244 off += timezone_names[i].dst;
245
246 /* Only use the tz name offset if we don't have anything better */
247 if (*offset == -1)
248 *offset = 60*off;
249
250 return match;
251 }
252 }
253
254 if (match_string(date, "PM") == 2) {
255 tm->tm_hour = (tm->tm_hour % 12) + 12;
256 return 2;
257 }
258
259 if (match_string(date, "AM") == 2) {
260 tm->tm_hour = (tm->tm_hour % 12) + 0;
261 return 2;
262 }
263
264 /* BAD CRAP */
265 return skip_alpha(date);
266 }
267
268 static int is_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
269 {
270 if (month > 0 && month < 13 && day > 0 && day < 32) {
271 struct tm check = *tm;
272 struct tm *r = (now_tm ? &check : tm);
273 time_t specified;
274
275 r->tm_mon = month - 1;
276 r->tm_mday = day;
277 if (year == -1) {
278 if (!now_tm)
279 return 1;
280 r->tm_year = now_tm->tm_year;
281 }
282 else if (year >= 1970 && year < 2100)
283 r->tm_year = year - 1900;
284 else if (year > 70 && year < 100)
285 r->tm_year = year;
286 else if (year < 38)
287 r->tm_year = year + 100;
288 else
289 return 0;
290 if (!now_tm)
291 return 1;
292
293 specified = my_mktime(r);
294
295 /* Be it commit time or author time, it does not make
296 * sense to specify timestamp way into the future. Make
297 * sure it is not later than ten days from now...
298 */
299 if (now + 10*24*3600 < specified)
300 return 0;
301 tm->tm_mon = r->tm_mon;
302 tm->tm_mday = r->tm_mday;
303 if (year != -1)
304 tm->tm_year = r->tm_year;
305 return 1;
306 }
307 return 0;
308 }
309
310 static int match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
311 {
312 time_t now;
313 struct tm now_tm;
314 struct tm *refuse_future;
315 long num2, num3;
316
317 num2 = strtol(end+1, &end, 10);
318 num3 = -1;
319 if (*end == c && isdigit(end[1]))
320 num3 = strtol(end+1, &end, 10);
321
322 /* Time? Date? */
323 switch (c) {
324 case ':':
325 if (num3 < 0)
326 num3 = 0;
327 if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
328 tm->tm_hour = num;
329 tm->tm_min = num2;
330 tm->tm_sec = num3;
331 break;
332 }
333 return 0;
334
335 case '-':
336 case '/':
337 case '.':
338 now = time(NULL);
339 refuse_future = NULL;
340 if (gmtime_r(&now, &now_tm))
341 refuse_future = &now_tm;
342
343 if (num > 70) {
344 /* yyyy-mm-dd? */
345 if (is_date(num, num2, num3, refuse_future, now, tm))
346 break;
347 /* yyyy-dd-mm? */
348 if (is_date(num, num3, num2, refuse_future, now, tm))
349 break;
350 }
351 /* Our eastern European friends say dd.mm.yy[yy]
352 * is the norm there, so giving precedence to
353 * mm/dd/yy[yy] form only when separator is not '.'
354 */
355 if (c != '.' &&
356 is_date(num3, num, num2, refuse_future, now, tm))
357 break;
358 /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
359 if (is_date(num3, num2, num, refuse_future, now, tm))
360 break;
361 /* Funny European mm.dd.yy */
362 if (c == '.' &&
363 is_date(num3, num, num2, refuse_future, now, tm))
364 break;
365 return 0;
366 }
367 return end - date;
368 }
369
370 /*
371 * We've seen a digit. Time? Year? Date?
372 */
373 static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
374 {
375 int n;
376 char *end;
377 unsigned long num;
378
379 num = strtoul(date, &end, 10);
380
381 /*
382 * Seconds since 1970? We trigger on that for anything after Jan 1, 2000
383 */
384 if (num > 946684800) {
385 time_t time = num;
386 if (gmtime_r(&time, tm)) {
387 *tm_gmt = 1;
388 return end - date;
389 }
390 }
391
392 /*
393 * Check for special formats: num[-.:/]num[same]num
394 */
395 switch (*end) {
396 case ':':
397 case '.':
398 case '/':
399 case '-':
400 if (isdigit(end[1])) {
401 int match = match_multi_number(num, *end, date, end, tm);
402 if (match)
403 return match;
404 }
405 }
406
407 /*
408 * None of the special formats? Try to guess what
409 * the number meant. We use the number of digits
410 * to make a more educated guess..
411 */
412 n = 0;
413 do {
414 n++;
415 } while (isdigit(date[n]));
416
417 /* Four-digit year or a timezone? */
418 if (n == 4) {
419 if (num <= 1400 && *offset == -1) {
420 unsigned int minutes = num % 100;
421 unsigned int hours = num / 100;
422 *offset = hours*60 + minutes;
423 } else if (num > 1900 && num < 2100)
424 tm->tm_year = num - 1900;
425 return n;
426 }
427
428 /*
429 * NOTE! We will give precedence to day-of-month over month or
430 * year numbers in the 1-12 range. So 05 is always "mday 5",
431 * unless we already have a mday..
432 *
433 * IOW, 01 Apr 05 parses as "April 1st, 2005".
434 */
435 if (num > 0 && num < 32 && tm->tm_mday < 0) {
436 tm->tm_mday = num;
437 return n;
438 }
439
440 /* Two-digit year? */
441 if (n == 2 && tm->tm_year < 0) {
442 if (num < 10 && tm->tm_mday >= 0) {
443 tm->tm_year = num + 100;
444 return n;
445 }
446 if (num >= 70) {
447 tm->tm_year = num;
448 return n;
449 }
450 }
451
452 if (num > 0 && num < 32) {
453 tm->tm_mday = num;
454 } else if (num > 1900) {
455 tm->tm_year = num - 1900;
456 } else if (num > 70) {
457 tm->tm_year = num;
458 } else if (num > 0 && num < 13) {
459 tm->tm_mon = num-1;
460 }
461
462 return n;
463 }
464
465 static int match_tz(const char *date, int *offp)
466 {
467 char *end;
468 int offset = strtoul(date+1, &end, 10);
469 int min, hour;
470 int n = end - date - 1;
471
472 min = offset % 100;
473 hour = offset / 100;
474
475 /*
476 * Don't accept any random crap.. At least 3 digits, and
477 * a valid minute. We might want to check that the minutes
478 * are divisible by 30 or something too.
479 */
480 if (min < 60 && n > 2) {
481 offset = hour*60+min;
482 if (*date == '-')
483 offset = -offset;
484
485 *offp = offset;
486 }
487 return end - date;
488 }
489
490 static int date_string(unsigned long date, int offset, char *buf, int len)
491 {
492 int sign = '+';
493
494 if (offset < 0) {
495 offset = -offset;
496 sign = '-';
497 }
498 return snprintf(buf, len, "%lu %c%02d%02d", date, sign, offset / 60, offset % 60);
499 }
500
501 /* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
502 (i.e. English) day/month names, and it doesn't work correctly with %z. */
503 int parse_date(const char *date, char *result, int maxlen)
504 {
505 struct tm tm;
506 int offset, tm_gmt;
507 time_t then;
508
509 memset(&tm, 0, sizeof(tm));
510 tm.tm_year = -1;
511 tm.tm_mon = -1;
512 tm.tm_mday = -1;
513 tm.tm_isdst = -1;
514 offset = -1;
515 tm_gmt = 0;
516
517 for (;;) {
518 int match = 0;
519 unsigned char c = *date;
520
521 /* Stop at end of string or newline */
522 if (!c || c == '\n')
523 break;
524
525 if (isalpha(c))
526 match = match_alpha(date, &tm, &offset);
527 else if (isdigit(c))
528 match = match_digit(date, &tm, &offset, &tm_gmt);
529 else if ((c == '-' || c == '+') && isdigit(date[1]))
530 match = match_tz(date, &offset);
531
532 if (!match) {
533 /* BAD CRAP */
534 match = 1;
535 }
536
537 date += match;
538 }
539
540 /* mktime uses local timezone */
541 then = my_mktime(&tm);
542 if (offset == -1)
543 offset = (then - mktime(&tm)) / 60;
544
545 if (then == -1)
546 return -1;
547
548 if (!tm_gmt)
549 then -= offset * 60;
550 return date_string(then, offset, result, maxlen);
551 }
552
553 void datestamp(char *buf, int bufsize)
554 {
555 time_t now;
556 int offset;
557
558 time(&now);
559
560 offset = my_mktime(localtime(&now)) - now;
561 offset /= 60;
562
563 date_string(now, offset, buf, bufsize);
564 }
565
566 static void update_tm(struct tm *tm, unsigned long sec)
567 {
568 time_t n = mktime(tm) - sec;
569 localtime_r(&n, tm);
570 }
571
572 static void date_yesterday(struct tm *tm, int *num)
573 {
574 update_tm(tm, 24*60*60);
575 }
576
577 static void date_time(struct tm *tm, int hour)
578 {
579 if (tm->tm_hour < hour)
580 date_yesterday(tm, NULL);
581 tm->tm_hour = hour;
582 tm->tm_min = 0;
583 tm->tm_sec = 0;
584 }
585
586 static void date_midnight(struct tm *tm, int *num)
587 {
588 date_time(tm, 0);
589 }
590
591 static void date_noon(struct tm *tm, int *num)
592 {
593 date_time(tm, 12);
594 }
595
596 static void date_tea(struct tm *tm, int *num)
597 {
598 date_time(tm, 17);
599 }
600
601 static void date_pm(struct tm *tm, int *num)
602 {
603 int hour, n = *num;
604 *num = 0;
605
606 hour = tm->tm_hour;
607 if (n) {
608 hour = n;
609 tm->tm_min = 0;
610 tm->tm_sec = 0;
611 }
612 tm->tm_hour = (hour % 12) + 12;
613 }
614
615 static void date_am(struct tm *tm, int *num)
616 {
617 int hour, n = *num;
618 *num = 0;
619
620 hour = tm->tm_hour;
621 if (n) {
622 hour = n;
623 tm->tm_min = 0;
624 tm->tm_sec = 0;
625 }
626 tm->tm_hour = (hour % 12);
627 }
628
629 static const struct special {
630 const char *name;
631 void (*fn)(struct tm *, int *);
632 } special[] = {
633 { "yesterday", date_yesterday },
634 { "noon", date_noon },
635 { "midnight", date_midnight },
636 { "tea", date_tea },
637 { "PM", date_pm },
638 { "AM", date_am },
639 { NULL }
640 };
641
642 static const char *number_name[] = {
643 "zero", "one", "two", "three", "four",
644 "five", "six", "seven", "eight", "nine", "ten",
645 };
646
647 static const struct typelen {
648 const char *type;
649 int length;
650 } typelen[] = {
651 { "seconds", 1 },
652 { "minutes", 60 },
653 { "hours", 60*60 },
654 { "days", 24*60*60 },
655 { "weeks", 7*24*60*60 },
656 { NULL }
657 };
658
659 static const char *approxidate_alpha(const char *date, struct tm *tm, int *num)
660 {
661 const struct typelen *tl;
662 const struct special *s;
663 const char *end = date;
664 int i;
665
666 while (isalpha(*++end));
667 ;
668
669 for (i = 0; i < 12; i++) {
670 int match = match_string(date, month_names[i]);
671 if (match >= 3) {
672 tm->tm_mon = i;
673 return end;
674 }
675 }
676
677 for (s = special; s->name; s++) {
678 int len = strlen(s->name);
679 if (match_string(date, s->name) == len) {
680 s->fn(tm, num);
681 return end;
682 }
683 }
684
685 if (!*num) {
686 for (i = 1; i < 11; i++) {
687 int len = strlen(number_name[i]);
688 if (match_string(date, number_name[i]) == len) {
689 *num = i;
690 return end;
691 }
692 }
693 if (match_string(date, "last") == 4)
694 *num = 1;
695 return end;
696 }
697
698 tl = typelen;
699 while (tl->type) {
700 int len = strlen(tl->type);
701 if (match_string(date, tl->type) >= len-1) {
702 update_tm(tm, tl->length * *num);
703 *num = 0;
704 return end;
705 }
706 tl++;
707 }
708
709 for (i = 0; i < 7; i++) {
710 int match = match_string(date, weekday_names[i]);
711 if (match >= 3) {
712 int diff, n = *num -1;
713 *num = 0;
714
715 diff = tm->tm_wday - i;
716 if (diff <= 0)
717 n++;
718 diff += 7*n;
719
720 update_tm(tm, diff * 24 * 60 * 60);
721 return end;
722 }
723 }
724
725 if (match_string(date, "months") >= 5) {
726 int n = tm->tm_mon - *num;
727 *num = 0;
728 while (n < 0) {
729 n += 12;
730 tm->tm_year--;
731 }
732 tm->tm_mon = n;
733 return end;
734 }
735
736 if (match_string(date, "years") >= 4) {
737 tm->tm_year -= *num;
738 *num = 0;
739 return end;
740 }
741
742 return end;
743 }
744
745 static const char *approxidate_digit(const char *date, struct tm *tm, int *num)
746 {
747 char *end;
748 unsigned long number = strtoul(date, &end, 10);
749
750 switch (*end) {
751 case ':':
752 case '.':
753 case '/':
754 case '-':
755 if (isdigit(end[1])) {
756 int match = match_multi_number(number, *end, date, end, tm);
757 if (match)
758 return date + match;
759 }
760 }
761
762 *num = number;
763 return end;
764 }
765
766 unsigned long approxidate(const char *date)
767 {
768 int number = 0;
769 struct tm tm, now;
770 struct timeval tv;
771 char buffer[50];
772
773 if (parse_date(date, buffer, sizeof(buffer)) > 0)
774 return strtoul(buffer, NULL, 10);
775
776 gettimeofday(&tv, NULL);
777 localtime_r(&tv.tv_sec, &tm);
778 now = tm;
779 for (;;) {
780 unsigned char c = *date;
781 if (!c)
782 break;
783 date++;
784 if (isdigit(c)) {
785 date = approxidate_digit(date-1, &tm, &number);
786 continue;
787 }
788 if (isalpha(c))
789 date = approxidate_alpha(date-1, &tm, &number);
790 }
791 if (number > 0 && number < 32)
792 tm.tm_mday = number;
793 if (tm.tm_mon > now.tm_mon && tm.tm_year == now.tm_year)
794 tm.tm_year--;
795 return mktime(&tm);
796 }