date.con commit blame: show "previous" information in --porcelain/--incremental format (96e1170)
   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 */
  12time_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
  31static const char *month_names[] = {
  32        "January", "February", "March", "April", "May", "June",
  33        "July", "August", "September", "October", "November", "December"
  34};
  35
  36static const char *weekday_names[] = {
  37        "Sundays", "Mondays", "Tuesdays", "Wednesdays", "Thursdays", "Fridays", "Saturdays"
  38};
  39
  40static 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 */
  55static 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 */
  65static 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
  87const 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 */
 173static 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
 225static 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
 241static 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*/
 253static 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
 303static 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
 345static 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? */
 406static 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 */
 417static 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
 514static 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
 539static 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. */
 552int 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
 602enum 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
 622void 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
 635static void update_tm(struct tm *tm, unsigned long sec)
 636{
 637        time_t n = mktime(tm) - sec;
 638        localtime_r(&n, tm);
 639}
 640
 641static void date_yesterday(struct tm *tm, int *num)
 642{
 643        update_tm(tm, 24*60*60);
 644}
 645
 646static 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
 655static void date_midnight(struct tm *tm, int *num)
 656{
 657        date_time(tm, 0);
 658}
 659
 660static void date_noon(struct tm *tm, int *num)
 661{
 662        date_time(tm, 12);
 663}
 664
 665static void date_tea(struct tm *tm, int *num)
 666{
 667        date_time(tm, 17);
 668}
 669
 670static 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
 684static 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
 698static void date_never(struct tm *tm, int *num)
 699{
 700        time_t n = 0;
 701        localtime_r(&n, tm);
 702}
 703
 704static 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
 718static const char *number_name[] = {
 719        "zero", "one", "two", "three", "four",
 720        "five", "six", "seven", "eight", "nine", "ten",
 721};
 722
 723static 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
 735static 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
 821static 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
 844unsigned 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}