Andrew's git / gitweb.git / date.c
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date.con commit Add howto about separating topics. (5b766ea)
   1/*
   2 * GIT - The information manager from hell
   3 *
   4 * Copyright (C) Linus Torvalds, 2005
   5 */
   6
   7#include <time.h>
   8#include <sys/time.h>
   9
  10#include "cache.h"
  11
  12static time_t my_mktime(struct tm *tm)
  13{
  14        static const int mdays[] = {
  15            0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
  16        };
  17        int year = tm->tm_year - 70;
  18        int month = tm->tm_mon;
  19        int day = tm->tm_mday;
  20
  21        if (year < 0 || year > 129) /* algo only works for 1970-2099 */
  22                return -1;
  23        if (month < 0 || month > 11) /* array bounds */
  24                return -1;
  25        if (month < 2 || (year + 2) % 4)
  26                day--;
  27        return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
  28                tm->tm_hour * 60*60 + tm->tm_min * 60 + tm->tm_sec;
  29}
  30
  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
  40/*
  41 * The "tz" thing is passed in as this strange "decimal parse of tz"
  42 * thing, which means that tz -0100 is passed in as the integer -100,
  43 * even though it means "sixty minutes off"
  44 */
  45const char *show_date(unsigned long time, int tz)
  46{
  47        struct tm *tm;
  48        time_t t;
  49        static char timebuf[200];
  50        int minutes;
  51
  52        minutes = tz < 0 ? -tz : tz;
  53        minutes = (minutes / 100)*60 + (minutes % 100);
  54        minutes = tz < 0 ? -minutes : minutes;
  55        t = time + minutes * 60;
  56        tm = gmtime(&t);
  57        if (!tm)
  58                return NULL;
  59        sprintf(timebuf, "%.3s %.3s %d %02d:%02d:%02d %d %+05d",
  60                weekday_names[tm->tm_wday],
  61                month_names[tm->tm_mon],
  62                tm->tm_mday,
  63                tm->tm_hour, tm->tm_min, tm->tm_sec,
  64                tm->tm_year + 1900, tz);
  65        return timebuf;
  66}
  67
  68/*
  69 * Check these. And note how it doesn't do the summer-time conversion.
  70 *
  71 * In my world, it's always summer, and things are probably a bit off
  72 * in other ways too.
  73 */
  74static const struct {
  75        const char *name;
  76        int offset;
  77        int dst;
  78} timezone_names[] = {
  79        { "IDLW", -12, 0, },    /* International Date Line West */
  80        { "NT",   -11, 0, },    /* Nome */
  81        { "CAT",  -10, 0, },    /* Central Alaska */
  82        { "HST",  -10, 0, },    /* Hawaii Standard */
  83        { "HDT",  -10, 1, },    /* Hawaii Daylight */
  84        { "YST",   -9, 0, },    /* Yukon Standard */
  85        { "YDT",   -9, 1, },    /* Yukon Daylight */
  86        { "PST",   -8, 0, },    /* Pacific Standard */
  87        { "PDT",   -8, 1, },    /* Pacific Daylight */
  88        { "MST",   -7, 0, },    /* Mountain Standard */
  89        { "MDT",   -7, 1, },    /* Mountain Daylight */
  90        { "CST",   -6, 0, },    /* Central Standard */
  91        { "CDT",   -6, 1, },    /* Central Daylight */
  92        { "EST",   -5, 0, },    /* Eastern Standard */
  93        { "EDT",   -5, 1, },    /* Eastern Daylight */
  94        { "AST",   -3, 0, },    /* Atlantic Standard */
  95        { "ADT",   -3, 1, },    /* Atlantic Daylight */
  96        { "WAT",   -1, 0, },    /* West Africa */
  97
  98        { "GMT",    0, 0, },    /* Greenwich Mean */
  99        { "UTC",    0, 0, },    /* Universal (Coordinated) */
 100
 101        { "WET",    0, 0, },    /* Western European */
 102        { "BST",    0, 1, },    /* British Summer */
 103        { "CET",   +1, 0, },    /* Central European */
 104        { "MET",   +1, 0, },    /* Middle European */
 105        { "MEWT",  +1, 0, },    /* Middle European Winter */
 106        { "MEST",  +1, 1, },    /* Middle European Summer */
 107        { "CEST",  +1, 1, },    /* Central European Summer */
 108        { "MESZ",  +1, 1, },    /* Middle European Summer */
 109        { "FWT",   +1, 0, },    /* French Winter */
 110        { "FST",   +1, 1, },    /* French Summer */
 111        { "EET",   +2, 0, },    /* Eastern Europe, USSR Zone 1 */
 112        { "EEST",  +2, 1, },    /* Eastern European Daylight */
 113        { "WAST",  +7, 0, },    /* West Australian Standard */
 114        { "WADT",  +7, 1, },    /* West Australian Daylight */
 115        { "CCT",   +8, 0, },    /* China Coast, USSR Zone 7 */
 116        { "JST",   +9, 0, },    /* Japan Standard, USSR Zone 8 */
 117        { "EAST", +10, 0, },    /* Eastern Australian Standard */
 118        { "EADT", +10, 1, },    /* Eastern Australian Daylight */
 119        { "GST",  +10, 0, },    /* Guam Standard, USSR Zone 9 */
 120        { "NZT",  +11, 0, },    /* New Zealand */
 121        { "NZST", +11, 0, },    /* New Zealand Standard */
 122        { "NZDT", +11, 1, },    /* New Zealand Daylight */
 123        { "IDLE", +12, 0, },    /* International Date Line East */
 124};
 125
 126#define NR_TZ (sizeof(timezone_names) / sizeof(timezone_names[0]))
 127        
 128static int match_string(const char *date, const char *str)
 129{
 130        int i = 0;
 131
 132        for (i = 0; *date; date++, str++, i++) {
 133                if (*date == *str)
 134                        continue;
 135                if (toupper(*date) == toupper(*str))
 136                        continue;
 137                if (!isalnum(*date))
 138                        break;
 139                return 0;
 140        }
 141        return i;
 142}
 143
 144static int skip_alpha(const char *date)
 145{
 146        int i = 0;
 147        do {
 148                i++;
 149        } while (isalpha(date[i]));
 150        return i;
 151}
 152
 153/*
 154* Parse month, weekday, or timezone name
 155*/
 156static int match_alpha(const char *date, struct tm *tm, int *offset)
 157{
 158        int i;
 159
 160        for (i = 0; i < 12; i++) {
 161                int match = match_string(date, month_names[i]);
 162                if (match >= 3) {
 163                        tm->tm_mon = i;
 164                        return match;
 165                }
 166        }
 167
 168        for (i = 0; i < 7; i++) {
 169                int match = match_string(date, weekday_names[i]);
 170                if (match >= 3) {
 171                        tm->tm_wday = i;
 172                        return match;
 173                }
 174        }
 175
 176        for (i = 0; i < NR_TZ; i++) {
 177                int match = match_string(date, timezone_names[i].name);
 178                if (match >= 3) {
 179                        int off = timezone_names[i].offset;
 180
 181                        /* This is bogus, but we like summer */
 182                        off += timezone_names[i].dst;
 183
 184                        /* Only use the tz name offset if we don't have anything better */
 185                        if (*offset == -1)
 186                                *offset = 60*off;
 187
 188                        return match;
 189                }
 190        }
 191
 192        if (match_string(date, "PM") == 2) {
 193                if (tm->tm_hour > 0 && tm->tm_hour < 12)
 194                        tm->tm_hour += 12;
 195                return 2;
 196        }
 197
 198        /* BAD CRAP */
 199        return skip_alpha(date);
 200}
 201
 202static int is_date(int year, int month, int day, struct tm *tm)
 203{
 204        if (month > 0 && month < 13 && day > 0 && day < 32) {
 205                if (year == -1) {
 206                        tm->tm_mon = month-1;
 207                        tm->tm_mday = day;
 208                        return 1;
 209                }
 210                if (year >= 1970 && year < 2100) {
 211                        year -= 1900;
 212                } else if (year > 70 && year < 100) {
 213                        /* ok */
 214                } else if (year < 38) {
 215                        year += 100;
 216                } else
 217                        return 0;
 218
 219                tm->tm_mon = month-1;
 220                tm->tm_mday = day;
 221                tm->tm_year = year;
 222                return 1;
 223        }
 224        return 0;
 225}
 226
 227static int match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
 228{
 229        long num2, num3;
 230
 231        num2 = strtol(end+1, &end, 10);
 232        num3 = -1;
 233        if (*end == c && isdigit(end[1]))
 234                num3 = strtol(end+1, &end, 10);
 235
 236        /* Time? Date? */
 237        switch (c) {
 238        case ':':
 239                if (num3 < 0)
 240                        num3 = 0;
 241                if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
 242                        tm->tm_hour = num;
 243                        tm->tm_min = num2;
 244                        tm->tm_sec = num3;
 245                        break;
 246                }
 247                return 0;
 248
 249        case '-':
 250        case '/':
 251                if (num > 70) {
 252                        /* yyyy-mm-dd? */
 253                        if (is_date(num, num2, num3, tm))
 254                                break;
 255                        /* yyyy-dd-mm? */
 256                        if (is_date(num, num3, num2, tm))
 257                                break;
 258                }
 259                /* mm/dd/yy ? */
 260                if (is_date(num3, num2, num, tm))
 261                        break;
 262                /* dd/mm/yy ? */
 263                if (is_date(num3, num, num2, tm))
 264                        break;
 265                return 0;
 266        }
 267        return end - date;
 268}
 269
 270/*
 271 * We've seen a digit. Time? Year? Date? 
 272 */
 273static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
 274{
 275        int n;
 276        char *end;
 277        unsigned long num;
 278
 279        num = strtoul(date, &end, 10);
 280
 281        /*
 282         * Seconds since 1970? We trigger on that for anything after Jan 1, 2000
 283         */
 284        if (num > 946684800) {
 285                time_t time = num;
 286                if (gmtime_r(&time, tm)) {
 287                        *tm_gmt = 1;
 288                        return end - date;
 289                }
 290        }
 291
 292        /*
 293         * Check for special formats: num[:-/]num[same]num
 294         */
 295        switch (*end) {
 296        case ':':
 297        case '/':
 298        case '-':
 299                if (isdigit(end[1])) {
 300                        int match = match_multi_number(num, *end, date, end, tm);
 301                        if (match)
 302                                return match;
 303                }
 304        }
 305
 306        /*
 307         * None of the special formats? Try to guess what
 308         * the number meant. We use the number of digits
 309         * to make a more educated guess..
 310         */
 311        n = 0;
 312        do {
 313                n++;
 314        } while (isdigit(date[n]));
 315
 316        /* Four-digit year or a timezone? */
 317        if (n == 4) {
 318                if (num <= 1200 && *offset == -1) {
 319                        unsigned int minutes = num % 100;
 320                        unsigned int hours = num / 100;
 321                        *offset = hours*60 + minutes;
 322                } else if (num > 1900 && num < 2100)
 323                        tm->tm_year = num - 1900;
 324                return n;
 325        }
 326
 327        /*
 328         * NOTE! We will give precedence to day-of-month over month or
 329         * year numbers in the 1-12 range. So 05 is always "mday 5",
 330         * unless we already have a mday..
 331         *
 332         * IOW, 01 Apr 05 parses as "April 1st, 2005".
 333         */
 334        if (num > 0 && num < 32 && tm->tm_mday < 0) {
 335                tm->tm_mday = num;
 336                return n;
 337        }
 338
 339        /* Two-digit year? */
 340        if (n == 2 && tm->tm_year < 0) {
 341                if (num < 10 && tm->tm_mday >= 0) {
 342                        tm->tm_year = num + 100;
 343                        return n;
 344                }
 345                if (num >= 70) {
 346                        tm->tm_year = num;
 347                        return n;
 348                }
 349        }
 350
 351        if (num > 0 && num < 32) {
 352                tm->tm_mday = num;
 353        } else if (num > 1900) {
 354                tm->tm_year = num - 1900;
 355        } else if (num > 70) {
 356                tm->tm_year = num;
 357        } else if (num > 0 && num < 13) {
 358                tm->tm_mon = num-1;
 359        }
 360                
 361        return n;
 362}
 363
 364static int match_tz(const char *date, int *offp)
 365{
 366        char *end;
 367        int offset = strtoul(date+1, &end, 10);
 368        int min, hour;
 369        int n = end - date - 1;
 370
 371        min = offset % 100;
 372        hour = offset / 100;
 373
 374        /*
 375         * Don't accept any random crap.. At least 3 digits, and
 376         * a valid minute. We might want to check that the minutes
 377         * are divisible by 30 or something too.
 378         */
 379        if (min < 60 && n > 2) {
 380                offset = hour*60+min;
 381                if (*date == '-')
 382                        offset = -offset;
 383
 384                *offp = offset;
 385        }
 386        return end - date;
 387}
 388
 389static int date_string(unsigned long date, int offset, char *buf, int len)
 390{
 391        int sign = '+';
 392
 393        if (offset < 0) {
 394                offset = -offset;
 395                sign = '-';
 396        }
 397        return snprintf(buf, len, "%lu %c%02d%02d", date, sign, offset / 60, offset % 60);
 398}
 399
 400/* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
 401   (i.e. English) day/month names, and it doesn't work correctly with %z. */
 402int parse_date(const char *date, char *result, int maxlen)
 403{
 404        struct tm tm;
 405        int offset, tm_gmt;
 406        time_t then;
 407
 408        memset(&tm, 0, sizeof(tm));
 409        tm.tm_year = -1;
 410        tm.tm_mon = -1;
 411        tm.tm_mday = -1;
 412        tm.tm_isdst = -1;
 413        offset = -1;
 414        tm_gmt = 0;
 415
 416        for (;;) {
 417                int match = 0;
 418                unsigned char c = *date;
 419
 420                /* Stop at end of string or newline */
 421                if (!c || c == '\n')
 422                        break;
 423
 424                if (isalpha(c))
 425                        match = match_alpha(date, &tm, &offset);
 426                else if (isdigit(c))
 427                        match = match_digit(date, &tm, &offset, &tm_gmt);
 428                else if ((c == '-' || c == '+') && isdigit(date[1]))
 429                        match = match_tz(date, &offset);
 430
 431                if (!match) {
 432                        /* BAD CRAP */
 433                        match = 1;
 434                }       
 435
 436                date += match;
 437        }
 438
 439        /* mktime uses local timezone */
 440        then = my_mktime(&tm); 
 441        if (offset == -1)
 442                offset = (then - mktime(&tm)) / 60;
 443
 444        if (then == -1)
 445                return -1;
 446
 447        if (!tm_gmt)
 448                then -= offset * 60;
 449        return date_string(then, offset, result, maxlen);
 450}
 451
 452void datestamp(char *buf, int bufsize)
 453{
 454        time_t now;
 455        int offset;
 456
 457        time(&now);
 458
 459        offset = my_mktime(localtime(&now)) - now;
 460        offset /= 60;
 461
 462        date_string(now, offset, buf, bufsize);
 463}
 464
 465static void update_tm(struct tm *tm, unsigned long sec)
 466{
 467        time_t n = mktime(tm) - sec;
 468        localtime_r(&n, tm);
 469}
 470
 471static void date_yesterday(struct tm *tm, int *num)
 472{
 473        update_tm(tm, 24*60*60);
 474}
 475
 476static void date_time(struct tm *tm, int hour)
 477{
 478        if (tm->tm_hour < hour)
 479                date_yesterday(tm, NULL);
 480        tm->tm_hour = hour;
 481        tm->tm_min = 0;
 482        tm->tm_sec = 0;
 483}
 484
 485static void date_midnight(struct tm *tm, int *num)
 486{
 487        date_time(tm, 0);
 488}
 489
 490static void date_noon(struct tm *tm, int *num)
 491{
 492        date_time(tm, 12);
 493}
 494
 495static void date_tea(struct tm *tm, int *num)
 496{
 497        date_time(tm, 17);
 498}
 499
 500static const struct special {
 501        const char *name;
 502        void (*fn)(struct tm *, int *);
 503} special[] = {
 504        { "yesterday", date_yesterday },
 505        { "noon", date_noon },
 506        { "midnight", date_midnight },
 507        { "tea", date_tea },
 508        { NULL }
 509};
 510
 511static const char *number_name[] = {
 512        "zero", "one", "two", "three", "four",
 513        "five", "six", "seven", "eight", "nine", "ten",
 514};
 515
 516static const struct typelen {
 517        const char *type;
 518        int length;
 519} typelen[] = {
 520        { "seconds", 1 },
 521        { "minutes", 60 },
 522        { "hours", 60*60 },
 523        { "days", 24*60*60 },
 524        { "weeks", 7*24*60*60 },
 525        { NULL }
 526};      
 527
 528static const char *approxidate_alpha(const char *date, struct tm *tm, int *num)
 529{
 530        const struct typelen *tl;
 531        const struct special *s;
 532        const char *end = date;
 533        int n = 1, i;
 534
 535        while (isalpha(*++end))
 536                n++;
 537
 538        for (i = 0; i < 12; i++) {
 539                int match = match_string(date, month_names[i]);
 540                if (match >= 3) {
 541                        tm->tm_mon = i;
 542                        return end;
 543                }
 544        }
 545
 546        for (s = special; s->name; s++) {
 547                int len = strlen(s->name);
 548                if (match_string(date, s->name) == len) {
 549                        s->fn(tm, num);
 550                        return end;
 551                }
 552        }
 553
 554        if (!*num) {
 555                for (i = 1; i < 11; i++) {
 556                        int len = strlen(number_name[i]);
 557                        if (match_string(date, number_name[i]) == len) {
 558                                *num = i;
 559                                return end;
 560                        }
 561                }
 562                if (match_string(date, "last") == 4)
 563                        *num = 1;
 564                return end;
 565        }
 566
 567        tl = typelen;
 568        while (tl->type) {
 569                int len = strlen(tl->type);
 570                if (match_string(date, tl->type) >= len-1) {
 571                        update_tm(tm, tl->length * *num);
 572                        *num = 0;
 573                        return end;
 574                }
 575                tl++;
 576        }
 577
 578        for (i = 0; i < 7; i++) {
 579                int match = match_string(date, weekday_names[i]);
 580                if (match >= 3) {
 581                        int diff, n = *num -1;
 582                        *num = 0;
 583
 584                        diff = tm->tm_wday - i;
 585                        if (diff <= 0)
 586                                n++;
 587                        diff += 7*n;
 588
 589                        update_tm(tm, diff * 24 * 60 * 60);
 590                        return end;
 591                }
 592        }
 593
 594        if (match_string(date, "months") >= 5) {
 595                int n = tm->tm_mon - *num;
 596                *num = 0;
 597                while (n < 0) {
 598                        n += 12;
 599                        tm->tm_year--;
 600                }
 601                tm->tm_mon = n;
 602                return end;
 603        }
 604
 605        if (match_string(date, "years") >= 4) {
 606                tm->tm_year -= *num;
 607                *num = 0;
 608                return end;
 609        }
 610
 611        return end;
 612}
 613
 614unsigned long approxidate(const char *date)
 615{
 616        int number = 0;
 617        struct tm tm, now;
 618        struct timeval tv;
 619        char buffer[50];
 620
 621        if (parse_date(date, buffer, sizeof(buffer)) > 0)
 622                return strtoul(buffer, NULL, 10);
 623
 624        gettimeofday(&tv, NULL);
 625        localtime_r(&tv.tv_sec, &tm);
 626        now = tm;
 627        for (;;) {
 628                unsigned char c = *date;
 629                if (!c)
 630                        break;
 631                date++;
 632                if (isdigit(c)) {
 633                        char *end;
 634                        number = strtoul(date-1, &end, 10);
 635                        date = end;
 636                        continue;
 637                }
 638                if (isalpha(c))
 639                        date = approxidate_alpha(date-1, &tm, &number);
 640        }
 641        if (number > 0 && number < 32)
 642                tm.tm_mday = number;
 643        if (tm.tm_mon > now.tm_mon && tm.tm_year == now.tm_year)
 644                tm.tm_year--;
 645        return mktime(&tm);
 646}