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