date.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  */
   6
   7 #include <time.h>
   8 #include <sys/time.h>
   9
  10 #include "cache.h"
  11
  12 static time_t my_mktime(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 /*
  41  * The "tz" thing is passed in as this strange "decimal parse of tz"
  42  * thing, which means that tz -0100 is passed in as the integer -100,
  43  * even though it means "sixty minutes off"
  44  */
  45 const char *show_date(unsigned long time, int tz)
  46 {
  47         struct tm *tm;
  48         time_t t;
  49         static char timebuf[200];
  50         int minutes;
  51
  52         minutes = tz < 0 ? -tz : tz;
  53         minutes = (minutes / 100)*60 + (minutes % 100);
  54         minutes = tz < 0 ? -minutes : minutes;
  55         t = time + minutes * 60;
  56         tm = gmtime(&t);
  57         if (!tm)
  58                 return NULL;
  59         sprintf(timebuf, "%.3s %.3s %d %02d:%02d:%02d %d %+05d",
  60                 weekday_names[tm->tm_wday],
  61                 month_names[tm->tm_mon],
  62                 tm->tm_mday,
  63                 tm->tm_hour, tm->tm_min, tm->tm_sec,
  64                 tm->tm_year + 1900, tz);
  65         return timebuf;
  66 }
  67
  68 /*
  69  * Check these. And note how it doesn't do the summer-time conversion.
  70  *
  71  * In my world, it's always summer, and things are probably a bit off
  72  * in other ways too.
  73  */
  74 static const struct {
  75         const char *name;
  76         int offset;
  77         int dst;
  78 } timezone_names[] = {
  79         { "IDLW", -12, 0, },    /* International Date Line West */
  80         { "NT",   -11, 0, },    /* Nome */
  81         { "CAT",  -10, 0, },    /* Central Alaska */
  82         { "HST",  -10, 0, },    /* Hawaii Standard */
  83         { "HDT",  -10, 1, },    /* Hawaii Daylight */
  84         { "YST",   -9, 0, },    /* Yukon Standard */
  85         { "YDT",   -9, 1, },    /* Yukon Daylight */
  86         { "PST",   -8, 0, },    /* Pacific Standard */
  87         { "PDT",   -8, 1, },    /* Pacific Daylight */
  88         { "MST",   -7, 0, },    /* Mountain Standard */
  89         { "MDT",   -7, 1, },    /* Mountain Daylight */
  90         { "CST",   -6, 0, },    /* Central Standard */
  91         { "CDT",   -6, 1, },    /* Central Daylight */
  92         { "EST",   -5, 0, },    /* Eastern Standard */
  93         { "EDT",   -5, 1, },    /* Eastern Daylight */
  94         { "AST",   -3, 0, },    /* Atlantic Standard */
  95         { "ADT",   -3, 1, },    /* Atlantic Daylight */
  96         { "WAT",   -1, 0, },    /* West Africa */
  97
  98         { "GMT",    0, 0, },    /* Greenwich Mean */
  99         { "UTC",    0, 0, },    /* Universal (Coordinated) */
 100
 101         { "WET",    0, 0, },    /* Western European */
 102         { "BST",    0, 1, },    /* British Summer */
 103         { "CET",   +1, 0, },    /* Central European */
 104         { "MET",   +1, 0, },    /* Middle European */
 105         { "MEWT",  +1, 0, },    /* Middle European Winter */
 106         { "MEST",  +1, 1, },    /* Middle European Summer */
 107         { "CEST",  +1, 1, },    /* Central European Summer */
 108         { "MESZ",  +1, 1, },    /* Middle European Summer */
 109         { "FWT",   +1, 0, },    /* French Winter */
 110         { "FST",   +1, 1, },    /* French Summer */
 111         { "EET",   +2, 0, },    /* Eastern Europe, USSR Zone 1 */
 112         { "EEST",  +2, 1, },    /* Eastern European Daylight */
 113         { "WAST",  +7, 0, },    /* West Australian Standard */
 114         { "WADT",  +7, 1, },    /* West Australian Daylight */
 115         { "CCT",   +8, 0, },    /* China Coast, USSR Zone 7 */
 116         { "JST",   +9, 0, },    /* Japan Standard, USSR Zone 8 */
 117         { "EAST", +10, 0, },    /* Eastern Australian Standard */
 118         { "EADT", +10, 1, },    /* Eastern Australian Daylight */
 119         { "GST",  +10, 0, },    /* Guam Standard, USSR Zone 9 */
 120         { "NZT",  +11, 0, },    /* New Zealand */
 121         { "NZST", +11, 0, },    /* New Zealand Standard */
 122         { "NZDT", +11, 1, },    /* New Zealand Daylight */
 123         { "IDLE", +12, 0, },    /* International Date Line East */
 124 };
 125
 126 static int match_string(const char *date, const char *str)
 127 {
 128         int i = 0;
 129
 130         for (i = 0; *date; date++, str++, i++) {
 131                 if (*date == *str)
 132                         continue;
 133                 if (toupper(*date) == toupper(*str))
 134                         continue;
 135                 if (!isalnum(*date))
 136                         break;
 137                 return 0;
 138         }
 139         return i;
 140 }
 141
 142 static int skip_alpha(const char *date)
 143 {
 144         int i = 0;
 145         do {
 146                 i++;
 147         } while (isalpha(date[i]));
 148         return i;
 149 }
 150
 151 /*
 152 * Parse month, weekday, or timezone name
 153 */
 154 static int match_alpha(const char *date, struct tm *tm, int *offset)
 155 {
 156         int i;
 157
 158         for (i = 0; i < 12; i++) {
 159                 int match = match_string(date, month_names[i]);
 160                 if (match >= 3) {
 161                         tm->tm_mon = i;
 162                         return match;
 163                 }
 164         }
 165
 166         for (i = 0; i < 7; i++) {
 167                 int match = match_string(date, weekday_names[i]);
 168                 if (match >= 3) {
 169                         tm->tm_wday = i;
 170                         return match;
 171                 }
 172         }
 173
 174         for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
 175                 int match = match_string(date, timezone_names[i].name);
 176                 if (match >= 3) {
 177                         int off = timezone_names[i].offset;
 178
 179                         /* This is bogus, but we like summer */
 180                         off += timezone_names[i].dst;
 181
 182                         /* Only use the tz name offset if we don't have anything better */
 183                         if (*offset == -1)
 184                                 *offset = 60*off;
 185
 186                         return match;
 187                 }
 188         }
 189
 190         if (match_string(date, "PM") == 2) {
 191                 if (tm->tm_hour > 0 && tm->tm_hour < 12)
 192                         tm->tm_hour += 12;
 193                 return 2;
 194         }
 195
 196         /* BAD CRAP */
 197         return skip_alpha(date);
 198 }
 199
 200 static int is_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
 201 {
 202         if (month > 0 && month < 13 && day > 0 && day < 32) {
 203                 struct tm check = *tm;
 204                 struct tm *r = (now_tm ? &check : tm);
 205                 time_t specified;
 206
 207                 r->tm_mon = month - 1;
 208                 r->tm_mday = day;
 209                 if (year == -1) {
 210                         if (!now_tm)
 211                                 return 1;
 212                         r->tm_year = now_tm->tm_year;
 213                 }
 214                 else if (year >= 1970 && year < 2100)
 215                         r->tm_year = year - 1900;
 216                 else if (year > 70 && year < 100)
 217                         r->tm_year = year;
 218                 else if (year < 38)
 219                         r->tm_year = year + 100;
 220                 else
 221                         return 0;
 222                 if (!now_tm)
 223                         return 1;
 224
 225                 specified = my_mktime(r);
 226
 227                 /* Be it commit time or author time, it does not make
 228                  * sense to specify timestamp way into the future.  Make
 229                  * sure it is not later than ten days from now...
 230                  */
 231                 if (now + 10*24*3600 < specified)
 232                         return 0;
 233                 tm->tm_mon = r->tm_mon;
 234                 tm->tm_mday = r->tm_mday;
 235                 if (year != -1)
 236                         tm->tm_year = r->tm_year;
 237                 return 1;
 238         }
 239         return 0;
 240 }
 241
 242 static int match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
 243 {
 244         time_t now;
 245         struct tm now_tm;
 246         struct tm *refuse_future;
 247         long num2, num3;
 248
 249         num2 = strtol(end+1, &end, 10);
 250         num3 = -1;
 251         if (*end == c && isdigit(end[1]))
 252                 num3 = strtol(end+1, &end, 10);
 253
 254         /* Time? Date? */
 255         switch (c) {
 256         case ':':
 257                 if (num3 < 0)
 258                         num3 = 0;
 259                 if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
 260                         tm->tm_hour = num;
 261                         tm->tm_min = num2;
 262                         tm->tm_sec = num3;
 263                         break;
 264                 }
 265                 return 0;
 266
 267         case '-':
 268         case '/':
 269         case '.':
 270                 now = time(NULL);
 271                 refuse_future = NULL;
 272                 if (gmtime_r(&now, &now_tm))
 273                         refuse_future = &now_tm;
 274
 275                 if (num > 70) {
 276                         /* yyyy-mm-dd? */
 277                         if (is_date(num, num2, num3, refuse_future, now, tm))
 278                                 break;
 279                         /* yyyy-dd-mm? */
 280                         if (is_date(num, num3, num2, refuse_future, now, tm))
 281                                 break;
 282                 }
 283                 /* Our eastern European friends say dd.mm.yy[yy]
 284                  * is the norm there, so giving precedence to
 285                  * mm/dd/yy[yy] form only when separator is not '.'
 286                  */
 287                 if (c != '.' &&
 288                     is_date(num3, num, num2, refuse_future, now, tm))
 289                         break;
 290                 /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
 291                 if (is_date(num3, num2, num, refuse_future, now, tm))
 292                         break;
 293                 /* Funny European mm.dd.yy */
 294                 if (c == '.' &&
 295                     is_date(num3, num, num2, refuse_future, now, tm))
 296                         break;
 297                 return 0;
 298         }
 299         return end - date;
 300 }
 301
 302 /*
 303  * We've seen a digit. Time? Year? Date?
 304  */
 305 static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
 306 {
 307         int n;
 308         char *end;
 309         unsigned long num;
 310
 311         num = strtoul(date, &end, 10);
 312
 313         /*
 314          * Seconds since 1970? We trigger on that for anything after Jan 1, 2000
 315          */
 316         if (num > 946684800) {
 317                 time_t time = num;
 318                 if (gmtime_r(&time, tm)) {
 319                         *tm_gmt = 1;
 320                         return end - date;
 321                 }
 322         }
 323
 324         /*
 325          * Check for special formats: num[-.:/]num[same]num
 326          */
 327         switch (*end) {
 328         case ':':
 329         case '.':
 330         case '/':
 331         case '-':
 332                 if (isdigit(end[1])) {
 333                         int match = match_multi_number(num, *end, date, end, tm);
 334                         if (match)
 335                                 return match;
 336                 }
 337         }
 338
 339         /*
 340          * None of the special formats? Try to guess what
 341          * the number meant. We use the number of digits
 342          * to make a more educated guess..
 343          */
 344         n = 0;
 345         do {
 346                 n++;
 347         } while (isdigit(date[n]));
 348
 349         /* Four-digit year or a timezone? */
 350         if (n == 4) {
 351                 if (num <= 1200 && *offset == -1) {
 352                         unsigned int minutes = num % 100;
 353                         unsigned int hours = num / 100;
 354                         *offset = hours*60 + minutes;
 355                 } else if (num > 1900 && num < 2100)
 356                         tm->tm_year = num - 1900;
 357                 return n;
 358         }
 359
 360         /*
 361          * NOTE! We will give precedence to day-of-month over month or
 362          * year numbers in the 1-12 range. So 05 is always "mday 5",
 363          * unless we already have a mday..
 364          *
 365          * IOW, 01 Apr 05 parses as "April 1st, 2005".
 366          */
 367         if (num > 0 && num < 32 && tm->tm_mday < 0) {
 368                 tm->tm_mday = num;
 369                 return n;
 370         }
 371
 372         /* Two-digit year? */
 373         if (n == 2 && tm->tm_year < 0) {
 374                 if (num < 10 && tm->tm_mday >= 0) {
 375                         tm->tm_year = num + 100;
 376                         return n;
 377                 }
 378                 if (num >= 70) {
 379                         tm->tm_year = num;
 380                         return n;
 381                 }
 382         }
 383
 384         if (num > 0 && num < 32) {
 385                 tm->tm_mday = num;
 386         } else if (num > 1900) {
 387                 tm->tm_year = num - 1900;
 388         } else if (num > 70) {
 389                 tm->tm_year = num;
 390         } else if (num > 0 && num < 13) {
 391                 tm->tm_mon = num-1;
 392         }
 393
 394         return n;
 395 }
 396
 397 static int match_tz(const char *date, int *offp)
 398 {
 399         char *end;
 400         int offset = strtoul(date+1, &end, 10);
 401         int min, hour;
 402         int n = end - date - 1;
 403
 404         min = offset % 100;
 405         hour = offset / 100;
 406
 407         /*
 408          * Don't accept any random crap.. At least 3 digits, and
 409          * a valid minute. We might want to check that the minutes
 410          * are divisible by 30 or something too.
 411          */
 412         if (min < 60 && n > 2) {
 413                 offset = hour*60+min;
 414                 if (*date == '-')
 415                         offset = -offset;
 416
 417                 *offp = offset;
 418         }
 419         return end - date;
 420 }
 421
 422 static int date_string(unsigned long date, int offset, char *buf, int len)
 423 {
 424         int sign = '+';
 425
 426         if (offset < 0) {
 427                 offset = -offset;
 428                 sign = '-';
 429         }
 430         return snprintf(buf, len, "%lu %c%02d%02d", date, sign, offset / 60, offset % 60);
 431 }
 432
 433 /* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
 434    (i.e. English) day/month names, and it doesn't work correctly with %z. */
 435 int parse_date(const char *date, char *result, int maxlen)
 436 {
 437         struct tm tm;
 438         int offset, tm_gmt;
 439         time_t then;
 440
 441         memset(&tm, 0, sizeof(tm));
 442         tm.tm_year = -1;
 443         tm.tm_mon = -1;
 444         tm.tm_mday = -1;
 445         tm.tm_isdst = -1;
 446         offset = -1;
 447         tm_gmt = 0;
 448
 449         for (;;) {
 450                 int match = 0;
 451                 unsigned char c = *date;
 452
 453                 /* Stop at end of string or newline */
 454                 if (!c || c == '\n')
 455                         break;
 456
 457                 if (isalpha(c))
 458                         match = match_alpha(date, &tm, &offset);
 459                 else if (isdigit(c))
 460                         match = match_digit(date, &tm, &offset, &tm_gmt);
 461                 else if ((c == '-' || c == '+') && isdigit(date[1]))
 462                         match = match_tz(date, &offset);
 463
 464                 if (!match) {
 465                         /* BAD CRAP */
 466                         match = 1;
 467                 }
 468
 469                 date += match;
 470         }
 471
 472         /* mktime uses local timezone */
 473         then = my_mktime(&tm);
 474         if (offset == -1)
 475                 offset = (then - mktime(&tm)) / 60;
 476
 477         if (then == -1)
 478                 return -1;
 479
 480         if (!tm_gmt)
 481                 then -= offset * 60;
 482         return date_string(then, offset, result, maxlen);
 483 }
 484
 485 void datestamp(char *buf, int bufsize)
 486 {
 487         time_t now;
 488         int offset;
 489
 490         time(&now);
 491
 492         offset = my_mktime(localtime(&now)) - now;
 493         offset /= 60;
 494
 495         date_string(now, offset, buf, bufsize);
 496 }
 497
 498 static void update_tm(struct tm *tm, unsigned long sec)
 499 {
 500         time_t n = mktime(tm) - sec;
 501         localtime_r(&n, tm);
 502 }
 503
 504 static void date_yesterday(struct tm *tm, int *num)
 505 {
 506         update_tm(tm, 24*60*60);
 507 }
 508
 509 static void date_time(struct tm *tm, int hour)
 510 {
 511         if (tm->tm_hour < hour)
 512                 date_yesterday(tm, NULL);
 513         tm->tm_hour = hour;
 514         tm->tm_min = 0;
 515         tm->tm_sec = 0;
 516 }
 517
 518 static void date_midnight(struct tm *tm, int *num)
 519 {
 520         date_time(tm, 0);
 521 }
 522
 523 static void date_noon(struct tm *tm, int *num)
 524 {
 525         date_time(tm, 12);
 526 }
 527
 528 static void date_tea(struct tm *tm, int *num)
 529 {
 530         date_time(tm, 17);
 531 }
 532
 533 static const struct special {
 534         const char *name;
 535         void (*fn)(struct tm *, int *);
 536 } special[] = {
 537         { "yesterday", date_yesterday },
 538         { "noon", date_noon },
 539         { "midnight", date_midnight },
 540         { "tea", date_tea },
 541         { NULL }
 542 };
 543
 544 static const char *number_name[] = {
 545         "zero", "one", "two", "three", "four",
 546         "five", "six", "seven", "eight", "nine", "ten",
 547 };
 548
 549 static const struct typelen {
 550         const char *type;
 551         int length;
 552 } typelen[] = {
 553         { "seconds", 1 },
 554         { "minutes", 60 },
 555         { "hours", 60*60 },
 556         { "days", 24*60*60 },
 557         { "weeks", 7*24*60*60 },
 558         { NULL }
 559 };
 560
 561 static const char *approxidate_alpha(const char *date, struct tm *tm, int *num)
 562 {
 563         const struct typelen *tl;
 564         const struct special *s;
 565         const char *end = date;
 566         int n = 1, i;
 567
 568         while (isalpha(*++end))
 569                 n++;
 570
 571         for (i = 0; i < 12; i++) {
 572                 int match = match_string(date, month_names[i]);
 573                 if (match >= 3) {
 574                         tm->tm_mon = i;
 575                         return end;
 576                 }
 577         }
 578
 579         for (s = special; s->name; s++) {
 580                 int len = strlen(s->name);
 581                 if (match_string(date, s->name) == len) {
 582                         s->fn(tm, num);
 583                         return end;
 584                 }
 585         }
 586
 587         if (!*num) {
 588                 for (i = 1; i < 11; i++) {
 589                         int len = strlen(number_name[i]);
 590                         if (match_string(date, number_name[i]) == len) {
 591                                 *num = i;
 592                                 return end;
 593                         }
 594                 }
 595                 if (match_string(date, "last") == 4)
 596                         *num = 1;
 597                 return end;
 598         }
 599
 600         tl = typelen;
 601         while (tl->type) {
 602                 int len = strlen(tl->type);
 603                 if (match_string(date, tl->type) >= len-1) {
 604                         update_tm(tm, tl->length * *num);
 605                         *num = 0;
 606                         return end;
 607                 }
 608                 tl++;
 609         }
 610
 611         for (i = 0; i < 7; i++) {
 612                 int match = match_string(date, weekday_names[i]);
 613                 if (match >= 3) {
 614                         int diff, n = *num -1;
 615                         *num = 0;
 616
 617                         diff = tm->tm_wday - i;
 618                         if (diff <= 0)
 619                                 n++;
 620                         diff += 7*n;
 621
 622                         update_tm(tm, diff * 24 * 60 * 60);
 623                         return end;
 624                 }
 625         }
 626
 627         if (match_string(date, "months") >= 5) {
 628                 int n = tm->tm_mon - *num;
 629                 *num = 0;
 630                 while (n < 0) {
 631                         n += 12;
 632                         tm->tm_year--;
 633                 }
 634                 tm->tm_mon = n;
 635                 return end;
 636         }
 637
 638         if (match_string(date, "years") >= 4) {
 639                 tm->tm_year -= *num;
 640                 *num = 0;
 641                 return end;
 642         }
 643
 644         return end;
 645 }
 646
 647 unsigned long approxidate(const char *date)
 648 {
 649         int number = 0;
 650         struct tm tm, now;
 651         struct timeval tv;
 652         char buffer[50];
 653
 654         if (parse_date(date, buffer, sizeof(buffer)) > 0)
 655                 return strtoul(buffer, NULL, 10);
 656
 657         gettimeofday(&tv, NULL);
 658         localtime_r(&tv.tv_sec, &tm);
 659         now = tm;
 660         for (;;) {
 661                 unsigned char c = *date;
 662                 if (!c)
 663                         break;
 664                 date++;
 665                 if (isdigit(c)) {
 666                         char *end;
 667                         number = strtoul(date-1, &end, 10);
 668                         date = end;
 669                         continue;
 670                 }
 671                 if (isalpha(c))
 672                         date = approxidate_alpha(date-1, &tm, &number);
 673         }
 674         if (number > 0 && number < 32)
 675                 tm.tm_mday = number;
 676         if (tm.tm_mon > now.tm_mon && tm.tm_year == now.tm_year)
 677                 tm.tm_year--;
 678         return mktime(&tm);
 679 }