date.c

   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         if (tm->tm_hour < 0 || tm->tm_min < 0 || tm->tm_sec < 0)
  28                 return -1;
  29         return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
  30                 tm->tm_hour * 60*60 + tm->tm_min * 60 + tm->tm_sec;
  31 }
  32
  33 static const char *month_names[] = {
  34         "January", "February", "March", "April", "May", "June",
  35         "July", "August", "September", "October", "November", "December"
  36 };
  37
  38 static const char *weekday_names[] = {
  39         "Sundays", "Mondays", "Tuesdays", "Wednesdays", "Thursdays", "Fridays", "Saturdays"
  40 };
  41
  42 static time_t gm_time_t(unsigned long time, int tz)
  43 {
  44         int minutes;
  45
  46         minutes = tz < 0 ? -tz : tz;
  47         minutes = (minutes / 100)*60 + (minutes % 100);
  48         minutes = tz < 0 ? -minutes : minutes;
  49         return time + minutes * 60;
  50 }
  51
  52 /*
  53  * The "tz" thing is passed in as this strange "decimal parse of tz"
  54  * thing, which means that tz -0100 is passed in as the integer -100,
  55  * even though it means "sixty minutes off"
  56  */
  57 static struct tm *time_to_tm(unsigned long time, int tz)
  58 {
  59         time_t t = gm_time_t(time, tz);
  60         return gmtime(&t);
  61 }
  62
  63 /*
  64  * What value of "tz" was in effect back then at "time" in the
  65  * local timezone?
  66  */
  67 static int local_tzoffset(unsigned long time)
  68 {
  69         time_t t, t_local;
  70         struct tm tm;
  71         int offset, eastwest;
  72
  73         t = time;
  74         localtime_r(&t, &tm);
  75         t_local = tm_to_time_t(&tm);
  76
  77         if (t_local < t) {
  78                 eastwest = -1;
  79                 offset = t - t_local;
  80         } else {
  81                 eastwest = 1;
  82                 offset = t_local - t;
  83         }
  84         offset /= 60; /* in minutes */
  85         offset = (offset % 60) + ((offset / 60) * 100);
  86         return offset * eastwest;
  87 }
  88
  89 const char *show_date_relative(unsigned long time, int tz,
  90                                const struct timeval *now,
  91                                char *timebuf,
  92                                size_t timebuf_size)
  93 {
  94         unsigned long diff;
  95         if (now->tv_sec < time)
  96                 return "in the future";
  97         diff = now->tv_sec - time;
  98         if (diff < 90) {
  99                 snprintf(timebuf, timebuf_size, "%lu seconds ago", diff);
 100                 return timebuf;
 101         }
 102         /* Turn it into minutes */
 103         diff = (diff + 30) / 60;
 104         if (diff < 90) {
 105                 snprintf(timebuf, timebuf_size, "%lu minutes ago", diff);
 106                 return timebuf;
 107         }
 108         /* Turn it into hours */
 109         diff = (diff + 30) / 60;
 110         if (diff < 36) {
 111                 snprintf(timebuf, timebuf_size, "%lu hours ago", diff);
 112                 return timebuf;
 113         }
 114         /* We deal with number of days from here on */
 115         diff = (diff + 12) / 24;
 116         if (diff < 14) {
 117                 snprintf(timebuf, timebuf_size, "%lu days ago", diff);
 118                 return timebuf;
 119         }
 120         /* Say weeks for the past 10 weeks or so */
 121         if (diff < 70) {
 122                 snprintf(timebuf, timebuf_size, "%lu weeks ago", (diff + 3) / 7);
 123                 return timebuf;
 124         }
 125         /* Say months for the past 12 months or so */
 126         if (diff < 365) {
 127                 snprintf(timebuf, timebuf_size, "%lu months ago", (diff + 15) / 30);
 128                 return timebuf;
 129         }
 130         /* Give years and months for 5 years or so */
 131         if (diff < 1825) {
 132                 unsigned long years = diff / 365;
 133                 unsigned long months = (diff % 365 + 15) / 30;
 134                 int n;
 135                 n = snprintf(timebuf, timebuf_size, "%lu year%s",
 136                                 years, (years > 1 ? "s" : ""));
 137                 if (months)
 138                         snprintf(timebuf + n, timebuf_size - n,
 139                                         ", %lu month%s ago",
 140                                         months, (months > 1 ? "s" : ""));
 141                 else
 142                         snprintf(timebuf + n, timebuf_size - n, " ago");
 143                 return timebuf;
 144         }
 145         /* Otherwise, just years. Centuries is probably overkill. */
 146         snprintf(timebuf, timebuf_size, "%lu years ago", (diff + 183) / 365);
 147         return timebuf;
 148 }
 149
 150 const char *show_date(unsigned long time, int tz, enum date_mode mode)
 151 {
 152         struct tm *tm;
 153         static char timebuf[200];
 154
 155         if (mode == DATE_RAW) {
 156                 snprintf(timebuf, sizeof(timebuf), "%lu %+05d", time, tz);
 157                 return timebuf;
 158         }
 159
 160         if (mode == DATE_RELATIVE) {
 161                 struct timeval now;
 162                 gettimeofday(&now, NULL);
 163                 return show_date_relative(time, tz, &now,
 164                                           timebuf, sizeof(timebuf));
 165         }
 166
 167         if (mode == DATE_LOCAL)
 168                 tz = local_tzoffset(time);
 169
 170         tm = time_to_tm(time, tz);
 171         if (!tm)
 172                 return NULL;
 173         if (mode == DATE_SHORT)
 174                 sprintf(timebuf, "%04d-%02d-%02d", tm->tm_year + 1900,
 175                                 tm->tm_mon + 1, tm->tm_mday);
 176         else if (mode == DATE_ISO8601)
 177                 sprintf(timebuf, "%04d-%02d-%02d %02d:%02d:%02d %+05d",
 178                                 tm->tm_year + 1900,
 179                                 tm->tm_mon + 1,
 180                                 tm->tm_mday,
 181                                 tm->tm_hour, tm->tm_min, tm->tm_sec,
 182                                 tz);
 183         else if (mode == DATE_RFC2822)
 184                 sprintf(timebuf, "%.3s, %d %.3s %d %02d:%02d:%02d %+05d",
 185                         weekday_names[tm->tm_wday], tm->tm_mday,
 186                         month_names[tm->tm_mon], tm->tm_year + 1900,
 187                         tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
 188         else
 189                 sprintf(timebuf, "%.3s %.3s %d %02d:%02d:%02d %d%c%+05d",
 190                                 weekday_names[tm->tm_wday],
 191                                 month_names[tm->tm_mon],
 192                                 tm->tm_mday,
 193                                 tm->tm_hour, tm->tm_min, tm->tm_sec,
 194                                 tm->tm_year + 1900,
 195                                 (mode == DATE_LOCAL) ? 0 : ' ',
 196                                 tz);
 197         return timebuf;
 198 }
 199
 200 /*
 201  * Check these. And note how it doesn't do the summer-time conversion.
 202  *
 203  * In my world, it's always summer, and things are probably a bit off
 204  * in other ways too.
 205  */
 206 static const struct {
 207         const char *name;
 208         int offset;
 209         int dst;
 210 } timezone_names[] = {
 211         { "IDLW", -12, 0, },    /* International Date Line West */
 212         { "NT",   -11, 0, },    /* Nome */
 213         { "CAT",  -10, 0, },    /* Central Alaska */
 214         { "HST",  -10, 0, },    /* Hawaii Standard */
 215         { "HDT",  -10, 1, },    /* Hawaii Daylight */
 216         { "YST",   -9, 0, },    /* Yukon Standard */
 217         { "YDT",   -9, 1, },    /* Yukon Daylight */
 218         { "PST",   -8, 0, },    /* Pacific Standard */
 219         { "PDT",   -8, 1, },    /* Pacific Daylight */
 220         { "MST",   -7, 0, },    /* Mountain Standard */
 221         { "MDT",   -7, 1, },    /* Mountain Daylight */
 222         { "CST",   -6, 0, },    /* Central Standard */
 223         { "CDT",   -6, 1, },    /* Central Daylight */
 224         { "EST",   -5, 0, },    /* Eastern Standard */
 225         { "EDT",   -5, 1, },    /* Eastern Daylight */
 226         { "AST",   -3, 0, },    /* Atlantic Standard */
 227         { "ADT",   -3, 1, },    /* Atlantic Daylight */
 228         { "WAT",   -1, 0, },    /* West Africa */
 229
 230         { "GMT",    0, 0, },    /* Greenwich Mean */
 231         { "UTC",    0, 0, },    /* Universal (Coordinated) */
 232
 233         { "WET",    0, 0, },    /* Western European */
 234         { "BST",    0, 1, },    /* British Summer */
 235         { "CET",   +1, 0, },    /* Central European */
 236         { "MET",   +1, 0, },    /* Middle European */
 237         { "MEWT",  +1, 0, },    /* Middle European Winter */
 238         { "MEST",  +1, 1, },    /* Middle European Summer */
 239         { "CEST",  +1, 1, },    /* Central European Summer */
 240         { "MESZ",  +1, 1, },    /* Middle European Summer */
 241         { "FWT",   +1, 0, },    /* French Winter */
 242         { "FST",   +1, 1, },    /* French Summer */
 243         { "EET",   +2, 0, },    /* Eastern Europe, USSR Zone 1 */
 244         { "EEST",  +2, 1, },    /* Eastern European Daylight */
 245         { "WAST",  +7, 0, },    /* West Australian Standard */
 246         { "WADT",  +7, 1, },    /* West Australian Daylight */
 247         { "CCT",   +8, 0, },    /* China Coast, USSR Zone 7 */
 248         { "JST",   +9, 0, },    /* Japan Standard, USSR Zone 8 */
 249         { "EAST", +10, 0, },    /* Eastern Australian Standard */
 250         { "EADT", +10, 1, },    /* Eastern Australian Daylight */
 251         { "GST",  +10, 0, },    /* Guam Standard, USSR Zone 9 */
 252         { "NZT",  +12, 0, },    /* New Zealand */
 253         { "NZST", +12, 0, },    /* New Zealand Standard */
 254         { "NZDT", +12, 1, },    /* New Zealand Daylight */
 255         { "IDLE", +12, 0, },    /* International Date Line East */
 256 };
 257
 258 static int match_string(const char *date, const char *str)
 259 {
 260         int i = 0;
 261
 262         for (i = 0; *date; date++, str++, i++) {
 263                 if (*date == *str)
 264                         continue;
 265                 if (toupper(*date) == toupper(*str))
 266                         continue;
 267                 if (!isalnum(*date))
 268                         break;
 269                 return 0;
 270         }
 271         return i;
 272 }
 273
 274 static int skip_alpha(const char *date)
 275 {
 276         int i = 0;
 277         do {
 278                 i++;
 279         } while (isalpha(date[i]));
 280         return i;
 281 }
 282
 283 /*
 284 * Parse month, weekday, or timezone name
 285 */
 286 static int match_alpha(const char *date, struct tm *tm, int *offset)
 287 {
 288         int i;
 289
 290         for (i = 0; i < 12; i++) {
 291                 int match = match_string(date, month_names[i]);
 292                 if (match >= 3) {
 293                         tm->tm_mon = i;
 294                         return match;
 295                 }
 296         }
 297
 298         for (i = 0; i < 7; i++) {
 299                 int match = match_string(date, weekday_names[i]);
 300                 if (match >= 3) {
 301                         tm->tm_wday = i;
 302                         return match;
 303                 }
 304         }
 305
 306         for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
 307                 int match = match_string(date, timezone_names[i].name);
 308                 if (match >= 3) {
 309                         int off = timezone_names[i].offset;
 310
 311                         /* This is bogus, but we like summer */
 312                         off += timezone_names[i].dst;
 313
 314                         /* Only use the tz name offset if we don't have anything better */
 315                         if (*offset == -1)
 316                                 *offset = 60*off;
 317
 318                         return match;
 319                 }
 320         }
 321
 322         if (match_string(date, "PM") == 2) {
 323                 tm->tm_hour = (tm->tm_hour % 12) + 12;
 324                 return 2;
 325         }
 326
 327         if (match_string(date, "AM") == 2) {
 328                 tm->tm_hour = (tm->tm_hour % 12) + 0;
 329                 return 2;
 330         }
 331
 332         /* BAD CRAP */
 333         return skip_alpha(date);
 334 }
 335
 336 static int is_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
 337 {
 338         if (month > 0 && month < 13 && day > 0 && day < 32) {
 339                 struct tm check = *tm;
 340                 struct tm *r = (now_tm ? &check : tm);
 341                 time_t specified;
 342
 343                 r->tm_mon = month - 1;
 344                 r->tm_mday = day;
 345                 if (year == -1) {
 346                         if (!now_tm)
 347                                 return 1;
 348                         r->tm_year = now_tm->tm_year;
 349                 }
 350                 else if (year >= 1970 && year < 2100)
 351                         r->tm_year = year - 1900;
 352                 else if (year > 70 && year < 100)
 353                         r->tm_year = year;
 354                 else if (year < 38)
 355                         r->tm_year = year + 100;
 356                 else
 357                         return 0;
 358                 if (!now_tm)
 359                         return 1;
 360
 361                 specified = tm_to_time_t(r);
 362
 363                 /* Be it commit time or author time, it does not make
 364                  * sense to specify timestamp way into the future.  Make
 365                  * sure it is not later than ten days from now...
 366                  */
 367                 if (now + 10*24*3600 < specified)
 368                         return 0;
 369                 tm->tm_mon = r->tm_mon;
 370                 tm->tm_mday = r->tm_mday;
 371                 if (year != -1)
 372                         tm->tm_year = r->tm_year;
 373                 return 1;
 374         }
 375         return 0;
 376 }
 377
 378 static int match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
 379 {
 380         time_t now;
 381         struct tm now_tm;
 382         struct tm *refuse_future;
 383         long num2, num3;
 384
 385         num2 = strtol(end+1, &end, 10);
 386         num3 = -1;
 387         if (*end == c && isdigit(end[1]))
 388                 num3 = strtol(end+1, &end, 10);
 389
 390         /* Time? Date? */
 391         switch (c) {
 392         case ':':
 393                 if (num3 < 0)
 394                         num3 = 0;
 395                 if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
 396                         tm->tm_hour = num;
 397                         tm->tm_min = num2;
 398                         tm->tm_sec = num3;
 399                         break;
 400                 }
 401                 return 0;
 402
 403         case '-':
 404         case '/':
 405         case '.':
 406                 now = time(NULL);
 407                 refuse_future = NULL;
 408                 if (gmtime_r(&now, &now_tm))
 409                         refuse_future = &now_tm;
 410
 411                 if (num > 70) {
 412                         /* yyyy-mm-dd? */
 413                         if (is_date(num, num2, num3, refuse_future, now, tm))
 414                                 break;
 415                         /* yyyy-dd-mm? */
 416                         if (is_date(num, num3, num2, refuse_future, now, tm))
 417                                 break;
 418                 }
 419                 /* Our eastern European friends say dd.mm.yy[yy]
 420                  * is the norm there, so giving precedence to
 421                  * mm/dd/yy[yy] form only when separator is not '.'
 422                  */
 423                 if (c != '.' &&
 424                     is_date(num3, num, num2, refuse_future, now, tm))
 425                         break;
 426                 /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
 427                 if (is_date(num3, num2, num, refuse_future, now, tm))
 428                         break;
 429                 /* Funny European mm.dd.yy */
 430                 if (c == '.' &&
 431                     is_date(num3, num, num2, refuse_future, now, tm))
 432                         break;
 433                 return 0;
 434         }
 435         return end - date;
 436 }
 437
 438 /*
 439  * Have we filled in any part of the time/date yet?
 440  * We just do a binary 'and' to see if the sign bit
 441  * is set in all the values.
 442  */
 443 static inline int nodate(struct tm *tm)
 444 {
 445         return (tm->tm_year &
 446                 tm->tm_mon &
 447                 tm->tm_mday &
 448                 tm->tm_hour &
 449                 tm->tm_min &
 450                 tm->tm_sec) < 0;
 451 }
 452
 453 /*
 454  * We've seen a digit. Time? Year? Date?
 455  */
 456 static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
 457 {
 458         int n;
 459         char *end;
 460         unsigned long num;
 461
 462         num = strtoul(date, &end, 10);
 463
 464         /*
 465          * Seconds since 1970? We trigger on that for any numbers with
 466          * more than 8 digits. This is because we don't want to rule out
 467          * numbers like 20070606 as a YYYYMMDD date.
 468          */
 469         if (num >= 100000000 && nodate(tm)) {
 470                 time_t time = num;
 471                 if (gmtime_r(&time, tm)) {
 472                         *tm_gmt = 1;
 473                         return end - date;
 474                 }
 475         }
 476
 477         /*
 478          * Check for special formats: num[-.:/]num[same]num
 479          */
 480         switch (*end) {
 481         case ':':
 482         case '.':
 483         case '/':
 484         case '-':
 485                 if (isdigit(end[1])) {
 486                         int match = match_multi_number(num, *end, date, end, tm);
 487                         if (match)
 488                                 return match;
 489                 }
 490         }
 491
 492         /*
 493          * None of the special formats? Try to guess what
 494          * the number meant. We use the number of digits
 495          * to make a more educated guess..
 496          */
 497         n = 0;
 498         do {
 499                 n++;
 500         } while (isdigit(date[n]));
 501
 502         /* Four-digit year or a timezone? */
 503         if (n == 4) {
 504                 if (num <= 1400 && *offset == -1) {
 505                         unsigned int minutes = num % 100;
 506                         unsigned int hours = num / 100;
 507                         *offset = hours*60 + minutes;
 508                 } else if (num > 1900 && num < 2100)
 509                         tm->tm_year = num - 1900;
 510                 return n;
 511         }
 512
 513         /*
 514          * Ignore lots of numerals. We took care of 4-digit years above.
 515          * Days or months must be one or two digits.
 516          */
 517         if (n > 2)
 518                 return n;
 519
 520         /*
 521          * NOTE! We will give precedence to day-of-month over month or
 522          * year numbers in the 1-12 range. So 05 is always "mday 5",
 523          * unless we already have a mday..
 524          *
 525          * IOW, 01 Apr 05 parses as "April 1st, 2005".
 526          */
 527         if (num > 0 && num < 32 && tm->tm_mday < 0) {
 528                 tm->tm_mday = num;
 529                 return n;
 530         }
 531
 532         /* Two-digit year? */
 533         if (n == 2 && tm->tm_year < 0) {
 534                 if (num < 10 && tm->tm_mday >= 0) {
 535                         tm->tm_year = num + 100;
 536                         return n;
 537                 }
 538                 if (num >= 70) {
 539                         tm->tm_year = num;
 540                         return n;
 541                 }
 542         }
 543
 544         if (num > 0 && num < 13 && tm->tm_mon < 0)
 545                 tm->tm_mon = num-1;
 546
 547         return n;
 548 }
 549
 550 static int match_tz(const char *date, int *offp)
 551 {
 552         char *end;
 553         int offset = strtoul(date+1, &end, 10);
 554         int min, hour;
 555         int n = end - date - 1;
 556
 557         min = offset % 100;
 558         hour = offset / 100;
 559
 560         /*
 561          * Don't accept any random crap.. At least 3 digits, and
 562          * a valid minute. We might want to check that the minutes
 563          * are divisible by 30 or something too.
 564          */
 565         if (min < 60 && n > 2) {
 566                 offset = hour*60+min;
 567                 if (*date == '-')
 568                         offset = -offset;
 569
 570                 *offp = offset;
 571         }
 572         return end - date;
 573 }
 574
 575 static int date_string(unsigned long date, int offset, char *buf, int len)
 576 {
 577         int sign = '+';
 578
 579         if (offset < 0) {
 580                 offset = -offset;
 581                 sign = '-';
 582         }
 583         return snprintf(buf, len, "%lu %c%02d%02d", date, sign, offset / 60, offset % 60);
 584 }
 585
 586 /* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
 587    (i.e. English) day/month names, and it doesn't work correctly with %z. */
 588 int parse_date(const char *date, char *result, int maxlen)
 589 {
 590         struct tm tm;
 591         int offset, tm_gmt;
 592         time_t then;
 593
 594         memset(&tm, 0, sizeof(tm));
 595         tm.tm_year = -1;
 596         tm.tm_mon = -1;
 597         tm.tm_mday = -1;
 598         tm.tm_isdst = -1;
 599         tm.tm_hour = -1;
 600         tm.tm_min = -1;
 601         tm.tm_sec = -1;
 602         offset = -1;
 603         tm_gmt = 0;
 604
 605         for (;;) {
 606                 int match = 0;
 607                 unsigned char c = *date;
 608
 609                 /* Stop at end of string or newline */
 610                 if (!c || c == '\n')
 611                         break;
 612
 613                 if (isalpha(c))
 614                         match = match_alpha(date, &tm, &offset);
 615                 else if (isdigit(c))
 616                         match = match_digit(date, &tm, &offset, &tm_gmt);
 617                 else if ((c == '-' || c == '+') && isdigit(date[1]))
 618                         match = match_tz(date, &offset);
 619
 620                 if (!match) {
 621                         /* BAD CRAP */
 622                         match = 1;
 623                 }
 624
 625                 date += match;
 626         }
 627
 628         /* mktime uses local timezone */
 629         then = tm_to_time_t(&tm);
 630         if (offset == -1)
 631                 offset = (then - mktime(&tm)) / 60;
 632
 633         if (then == -1)
 634                 return -1;
 635
 636         if (!tm_gmt)
 637                 then -= offset * 60;
 638         return date_string(then, offset, result, maxlen);
 639 }
 640
 641 enum date_mode parse_date_format(const char *format)
 642 {
 643         if (!strcmp(format, "relative"))
 644                 return DATE_RELATIVE;
 645         else if (!strcmp(format, "iso8601") ||
 646                  !strcmp(format, "iso"))
 647                 return DATE_ISO8601;
 648         else if (!strcmp(format, "rfc2822") ||
 649                  !strcmp(format, "rfc"))
 650                 return DATE_RFC2822;
 651         else if (!strcmp(format, "short"))
 652                 return DATE_SHORT;
 653         else if (!strcmp(format, "local"))
 654                 return DATE_LOCAL;
 655         else if (!strcmp(format, "default"))
 656                 return DATE_NORMAL;
 657         else if (!strcmp(format, "raw"))
 658                 return DATE_RAW;
 659         else
 660                 die("unknown date format %s", format);
 661 }
 662
 663 void datestamp(char *buf, int bufsize)
 664 {
 665         time_t now;
 666         int offset;
 667
 668         time(&now);
 669
 670         offset = tm_to_time_t(localtime(&now)) - now;
 671         offset /= 60;
 672
 673         date_string(now, offset, buf, bufsize);
 674 }
 675
 676 /*
 677  * Relative time update (eg "2 days ago").  If we haven't set the time
 678  * yet, we need to set it from current time.
 679  */
 680 static unsigned long update_tm(struct tm *tm, struct tm *now, unsigned long sec)
 681 {
 682         time_t n;
 683
 684         if (tm->tm_mday < 0)
 685                 tm->tm_mday = now->tm_mday;
 686         if (tm->tm_mon < 0)
 687                 tm->tm_mon = now->tm_mon;
 688         if (tm->tm_year < 0) {
 689                 tm->tm_year = now->tm_year;
 690                 if (tm->tm_mon > now->tm_mon)
 691                         tm->tm_year--;
 692         }
 693
 694         n = mktime(tm) - sec;
 695         localtime_r(&n, tm);
 696         return n;
 697 }
 698
 699 static void date_yesterday(struct tm *tm, struct tm *now, int *num)
 700 {
 701         update_tm(tm, now, 24*60*60);
 702 }
 703
 704 static void date_time(struct tm *tm, struct tm *now, int hour)
 705 {
 706         if (tm->tm_hour < hour)
 707                 date_yesterday(tm, now, NULL);
 708         tm->tm_hour = hour;
 709         tm->tm_min = 0;
 710         tm->tm_sec = 0;
 711 }
 712
 713 static void date_midnight(struct tm *tm, struct tm *now, int *num)
 714 {
 715         date_time(tm, now, 0);
 716 }
 717
 718 static void date_noon(struct tm *tm, struct tm *now, int *num)
 719 {
 720         date_time(tm, now, 12);
 721 }
 722
 723 static void date_tea(struct tm *tm, struct tm *now, int *num)
 724 {
 725         date_time(tm, now, 17);
 726 }
 727
 728 static void date_pm(struct tm *tm, struct tm *now, int *num)
 729 {
 730         int hour, n = *num;
 731         *num = 0;
 732
 733         hour = tm->tm_hour;
 734         if (n) {
 735                 hour = n;
 736                 tm->tm_min = 0;
 737                 tm->tm_sec = 0;
 738         }
 739         tm->tm_hour = (hour % 12) + 12;
 740 }
 741
 742 static void date_am(struct tm *tm, struct tm *now, int *num)
 743 {
 744         int hour, n = *num;
 745         *num = 0;
 746
 747         hour = tm->tm_hour;
 748         if (n) {
 749                 hour = n;
 750                 tm->tm_min = 0;
 751                 tm->tm_sec = 0;
 752         }
 753         tm->tm_hour = (hour % 12);
 754 }
 755
 756 static void date_never(struct tm *tm, struct tm *now, int *num)
 757 {
 758         time_t n = 0;
 759         localtime_r(&n, tm);
 760 }
 761
 762 static const struct special {
 763         const char *name;
 764         void (*fn)(struct tm *, struct tm *, int *);
 765 } special[] = {
 766         { "yesterday", date_yesterday },
 767         { "noon", date_noon },
 768         { "midnight", date_midnight },
 769         { "tea", date_tea },
 770         { "PM", date_pm },
 771         { "AM", date_am },
 772         { "never", date_never },
 773         { NULL }
 774 };
 775
 776 static const char *number_name[] = {
 777         "zero", "one", "two", "three", "four",
 778         "five", "six", "seven", "eight", "nine", "ten",
 779 };
 780
 781 static const struct typelen {
 782         const char *type;
 783         int length;
 784 } typelen[] = {
 785         { "seconds", 1 },
 786         { "minutes", 60 },
 787         { "hours", 60*60 },
 788         { "days", 24*60*60 },
 789         { "weeks", 7*24*60*60 },
 790         { NULL }
 791 };
 792
 793 static const char *approxidate_alpha(const char *date, struct tm *tm, struct tm *now, int *num)
 794 {
 795         const struct typelen *tl;
 796         const struct special *s;
 797         const char *end = date;
 798         int i;
 799
 800         while (isalpha(*++end));
 801                 ;
 802
 803         for (i = 0; i < 12; i++) {
 804                 int match = match_string(date, month_names[i]);
 805                 if (match >= 3) {
 806                         tm->tm_mon = i;
 807                         return end;
 808                 }
 809         }
 810
 811         for (s = special; s->name; s++) {
 812                 int len = strlen(s->name);
 813                 if (match_string(date, s->name) == len) {
 814                         s->fn(tm, now, num);
 815                         return end;
 816                 }
 817         }
 818
 819         if (!*num) {
 820                 for (i = 1; i < 11; i++) {
 821                         int len = strlen(number_name[i]);
 822                         if (match_string(date, number_name[i]) == len) {
 823                                 *num = i;
 824                                 return end;
 825                         }
 826                 }
 827                 if (match_string(date, "last") == 4)
 828                         *num = 1;
 829                 return end;
 830         }
 831
 832         tl = typelen;
 833         while (tl->type) {
 834                 int len = strlen(tl->type);
 835                 if (match_string(date, tl->type) >= len-1) {
 836                         update_tm(tm, now, tl->length * *num);
 837                         *num = 0;
 838                         return end;
 839                 }
 840                 tl++;
 841         }
 842
 843         for (i = 0; i < 7; i++) {
 844                 int match = match_string(date, weekday_names[i]);
 845                 if (match >= 3) {
 846                         int diff, n = *num -1;
 847                         *num = 0;
 848
 849                         diff = tm->tm_wday - i;
 850                         if (diff <= 0)
 851                                 n++;
 852                         diff += 7*n;
 853
 854                         update_tm(tm, now, diff * 24 * 60 * 60);
 855                         return end;
 856                 }
 857         }
 858
 859         if (match_string(date, "months") >= 5) {
 860                 int n;
 861                 update_tm(tm, now, 0); /* fill in date fields if needed */
 862                 n = tm->tm_mon - *num;
 863                 *num = 0;
 864                 while (n < 0) {
 865                         n += 12;
 866                         tm->tm_year--;
 867                 }
 868                 tm->tm_mon = n;
 869                 return end;
 870         }
 871
 872         if (match_string(date, "years") >= 4) {
 873                 update_tm(tm, now, 0); /* fill in date fields if needed */
 874                 tm->tm_year -= *num;
 875                 *num = 0;
 876                 return end;
 877         }
 878
 879         return end;
 880 }
 881
 882 static const char *approxidate_digit(const char *date, struct tm *tm, int *num)
 883 {
 884         char *end;
 885         unsigned long number = strtoul(date, &end, 10);
 886
 887         switch (*end) {
 888         case ':':
 889         case '.':
 890         case '/':
 891         case '-':
 892                 if (isdigit(end[1])) {
 893                         int match = match_multi_number(number, *end, date, end, tm);
 894                         if (match)
 895                                 return date + match;
 896                 }
 897         }
 898
 899         /* Accept zero-padding only for small numbers ("Dec 02", never "Dec 0002") */
 900         if (date[0] != '0' || end - date <= 2)
 901                 *num = number;
 902         return end;
 903 }
 904
 905 /*
 906  * Do we have a pending number at the end, or when
 907  * we see a new one? Let's assume it's a month day,
 908  * as in "Dec 6, 1992"
 909  */
 910 static void pending_number(struct tm *tm, int *num)
 911 {
 912         int number = *num;
 913
 914         if (number) {
 915                 *num = 0;
 916                 if (tm->tm_mday < 0 && number < 32)
 917                         tm->tm_mday = number;
 918                 else if (tm->tm_mon < 0 && number < 13)
 919                         tm->tm_mon = number-1;
 920                 else if (tm->tm_year < 0) {
 921                         if (number > 1969 && number < 2100)
 922                                 tm->tm_year = number - 1900;
 923                         else if (number > 69 && number < 100)
 924                                 tm->tm_year = number;
 925                         else if (number < 38)
 926                                 tm->tm_year = 100 + number;
 927                         /* We screw up for number = 00 ? */
 928                 }
 929         }
 930 }
 931
 932 static unsigned long approxidate_str(const char *date, const struct timeval *tv)
 933 {
 934         int number = 0;
 935         struct tm tm, now;
 936         time_t time_sec;
 937
 938         time_sec = tv->tv_sec;
 939         localtime_r(&time_sec, &tm);
 940         now = tm;
 941
 942         tm.tm_year = -1;
 943         tm.tm_mon = -1;
 944         tm.tm_mday = -1;
 945
 946         for (;;) {
 947                 unsigned char c = *date;
 948                 if (!c)
 949                         break;
 950                 date++;
 951                 if (isdigit(c)) {
 952                         pending_number(&tm, &number);
 953                         date = approxidate_digit(date-1, &tm, &number);
 954                         continue;
 955                 }
 956                 if (isalpha(c))
 957                         date = approxidate_alpha(date-1, &tm, &now, &number);
 958         }
 959         pending_number(&tm, &number);
 960         return update_tm(&tm, &now, 0);
 961 }
 962
 963 unsigned long approxidate_relative(const char *date, const struct timeval *tv)
 964 {
 965         char buffer[50];
 966
 967         if (parse_date(date, buffer, sizeof(buffer)) > 0)
 968                 return strtoul(buffer, NULL, 0);
 969
 970         return approxidate_str(date, tv);
 971 }
 972
 973 unsigned long approxidate(const char *date)
 974 {
 975         struct timeval tv;
 976         char buffer[50];
 977
 978         if (parse_date(date, buffer, sizeof(buffer)) > 0)
 979                 return strtoul(buffer, NULL, 0);
 980
 981         gettimeofday(&tv, NULL);
 982         return approxidate_str(date, &tv);
 983 }