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