Andrew's git / gitweb.git / date.c
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date.con commit gitview.txt: improve asciidoc markup (5bab25f)
   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 */
  45static struct tm *time_to_tm(unsigned long time, int tz)
  46{
  47        time_t t;
  48        int minutes;
  49
  50        minutes = tz < 0 ? -tz : tz;
  51        minutes = (minutes / 100)*60 + (minutes % 100);
  52        minutes = tz < 0 ? -minutes : minutes;
  53        t = time + minutes * 60;
  54        return gmtime(&t);
  55}
  56
  57const char *show_date(unsigned long time, int tz)
  58{
  59        struct tm *tm;
  60        static char timebuf[200];
  61
  62        tm = time_to_tm(time, tz);
  63        if (!tm)
  64                return NULL;
  65        sprintf(timebuf, "%.3s %.3s %d %02d:%02d:%02d %d %+05d",
  66                weekday_names[tm->tm_wday],
  67                month_names[tm->tm_mon],
  68                tm->tm_mday,
  69                tm->tm_hour, tm->tm_min, tm->tm_sec,
  70                tm->tm_year + 1900, tz);
  71        return timebuf;
  72}
  73
  74const char *show_rfc2822_date(unsigned long time, int tz)
  75{
  76        struct tm *tm;
  77        static char timebuf[200];
  78
  79        tm = time_to_tm(time, tz);
  80        if (!tm)
  81                return NULL;
  82        sprintf(timebuf, "%.3s, %d %.3s %d %02d:%02d:%02d %+05d",
  83                weekday_names[tm->tm_wday], tm->tm_mday,
  84                month_names[tm->tm_mon], tm->tm_year + 1900,
  85                tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
  86        return timebuf;
  87}
  88
  89/*
  90 * Check these. And note how it doesn't do the summer-time conversion.
  91 *
  92 * In my world, it's always summer, and things are probably a bit off
  93 * in other ways too.
  94 */
  95static const struct {
  96        const char *name;
  97        int offset;
  98        int dst;
  99} timezone_names[] = {
 100        { "IDLW", -12, 0, },    /* International Date Line West */
 101        { "NT",   -11, 0, },    /* Nome */
 102        { "CAT",  -10, 0, },    /* Central Alaska */
 103        { "HST",  -10, 0, },    /* Hawaii Standard */
 104        { "HDT",  -10, 1, },    /* Hawaii Daylight */
 105        { "YST",   -9, 0, },    /* Yukon Standard */
 106        { "YDT",   -9, 1, },    /* Yukon Daylight */
 107        { "PST",   -8, 0, },    /* Pacific Standard */
 108        { "PDT",   -8, 1, },    /* Pacific Daylight */
 109        { "MST",   -7, 0, },    /* Mountain Standard */
 110        { "MDT",   -7, 1, },    /* Mountain Daylight */
 111        { "CST",   -6, 0, },    /* Central Standard */
 112        { "CDT",   -6, 1, },    /* Central Daylight */
 113        { "EST",   -5, 0, },    /* Eastern Standard */
 114        { "EDT",   -5, 1, },    /* Eastern Daylight */
 115        { "AST",   -3, 0, },    /* Atlantic Standard */
 116        { "ADT",   -3, 1, },    /* Atlantic Daylight */
 117        { "WAT",   -1, 0, },    /* West Africa */
 118
 119        { "GMT",    0, 0, },    /* Greenwich Mean */
 120        { "UTC",    0, 0, },    /* Universal (Coordinated) */
 121
 122        { "WET",    0, 0, },    /* Western European */
 123        { "BST",    0, 1, },    /* British Summer */
 124        { "CET",   +1, 0, },    /* Central European */
 125        { "MET",   +1, 0, },    /* Middle European */
 126        { "MEWT",  +1, 0, },    /* Middle European Winter */
 127        { "MEST",  +1, 1, },    /* Middle European Summer */
 128        { "CEST",  +1, 1, },    /* Central European Summer */
 129        { "MESZ",  +1, 1, },    /* Middle European Summer */
 130        { "FWT",   +1, 0, },    /* French Winter */
 131        { "FST",   +1, 1, },    /* French Summer */
 132        { "EET",   +2, 0, },    /* Eastern Europe, USSR Zone 1 */
 133        { "EEST",  +2, 1, },    /* Eastern European Daylight */
 134        { "WAST",  +7, 0, },    /* West Australian Standard */
 135        { "WADT",  +7, 1, },    /* West Australian Daylight */
 136        { "CCT",   +8, 0, },    /* China Coast, USSR Zone 7 */
 137        { "JST",   +9, 0, },    /* Japan Standard, USSR Zone 8 */
 138        { "EAST", +10, 0, },    /* Eastern Australian Standard */
 139        { "EADT", +10, 1, },    /* Eastern Australian Daylight */
 140        { "GST",  +10, 0, },    /* Guam Standard, USSR Zone 9 */
 141        { "NZT",  +11, 0, },    /* New Zealand */
 142        { "NZST", +11, 0, },    /* New Zealand Standard */
 143        { "NZDT", +11, 1, },    /* New Zealand Daylight */
 144        { "IDLE", +12, 0, },    /* International Date Line East */
 145};
 146
 147static int match_string(const char *date, const char *str)
 148{
 149        int i = 0;
 150
 151        for (i = 0; *date; date++, str++, i++) {
 152                if (*date == *str)
 153                        continue;
 154                if (toupper(*date) == toupper(*str))
 155                        continue;
 156                if (!isalnum(*date))
 157                        break;
 158                return 0;
 159        }
 160        return i;
 161}
 162
 163static int skip_alpha(const char *date)
 164{
 165        int i = 0;
 166        do {
 167                i++;
 168        } while (isalpha(date[i]));
 169        return i;
 170}
 171
 172/*
 173* Parse month, weekday, or timezone name
 174*/
 175static int match_alpha(const char *date, struct tm *tm, int *offset)
 176{
 177        int i;
 178
 179        for (i = 0; i < 12; i++) {
 180                int match = match_string(date, month_names[i]);
 181                if (match >= 3) {
 182                        tm->tm_mon = i;
 183                        return match;
 184                }
 185        }
 186
 187        for (i = 0; i < 7; i++) {
 188                int match = match_string(date, weekday_names[i]);
 189                if (match >= 3) {
 190                        tm->tm_wday = i;
 191                        return match;
 192                }
 193        }
 194
 195        for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
 196                int match = match_string(date, timezone_names[i].name);
 197                if (match >= 3) {
 198                        int off = timezone_names[i].offset;
 199
 200                        /* This is bogus, but we like summer */
 201                        off += timezone_names[i].dst;
 202
 203                        /* Only use the tz name offset if we don't have anything better */
 204                        if (*offset == -1)
 205                                *offset = 60*off;
 206
 207                        return match;
 208                }
 209        }
 210
 211        if (match_string(date, "PM") == 2) {
 212                if (tm->tm_hour > 0 && tm->tm_hour < 12)
 213                        tm->tm_hour += 12;
 214                return 2;
 215        }
 216
 217        /* BAD CRAP */
 218        return skip_alpha(date);
 219}
 220
 221static int is_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
 222{
 223        if (month > 0 && month < 13 && day > 0 && day < 32) {
 224                struct tm check = *tm;
 225                struct tm *r = (now_tm ? &check : tm);
 226                time_t specified;
 227
 228                r->tm_mon = month - 1;
 229                r->tm_mday = day;
 230                if (year == -1) {
 231                        if (!now_tm)
 232                                return 1;
 233                        r->tm_year = now_tm->tm_year;
 234                }
 235                else if (year >= 1970 && year < 2100)
 236                        r->tm_year = year - 1900;
 237                else if (year > 70 && year < 100)
 238                        r->tm_year = year;
 239                else if (year < 38)
 240                        r->tm_year = year + 100;
 241                else
 242                        return 0;
 243                if (!now_tm)
 244                        return 1;
 245
 246                specified = my_mktime(r);
 247
 248                /* Be it commit time or author time, it does not make
 249                 * sense to specify timestamp way into the future.  Make
 250                 * sure it is not later than ten days from now...
 251                 */
 252                if (now + 10*24*3600 < specified)
 253                        return 0;
 254                tm->tm_mon = r->tm_mon;
 255                tm->tm_mday = r->tm_mday;
 256                if (year != -1)
 257                        tm->tm_year = r->tm_year;
 258                return 1;
 259        }
 260        return 0;
 261}
 262
 263static int match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
 264{
 265        time_t now;
 266        struct tm now_tm;
 267        struct tm *refuse_future;
 268        long num2, num3;
 269
 270        num2 = strtol(end+1, &end, 10);
 271        num3 = -1;
 272        if (*end == c && isdigit(end[1]))
 273                num3 = strtol(end+1, &end, 10);
 274
 275        /* Time? Date? */
 276        switch (c) {
 277        case ':':
 278                if (num3 < 0)
 279                        num3 = 0;
 280                if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
 281                        tm->tm_hour = num;
 282                        tm->tm_min = num2;
 283                        tm->tm_sec = num3;
 284                        break;
 285                }
 286                return 0;
 287
 288        case '-':
 289        case '/':
 290        case '.':
 291                now = time(NULL);
 292                refuse_future = NULL;
 293                if (gmtime_r(&now, &now_tm))
 294                        refuse_future = &now_tm;
 295
 296                if (num > 70) {
 297                        /* yyyy-mm-dd? */
 298                        if (is_date(num, num2, num3, refuse_future, now, tm))
 299                                break;
 300                        /* yyyy-dd-mm? */
 301                        if (is_date(num, num3, num2, refuse_future, now, tm))
 302                                break;
 303                }
 304                /* Our eastern European friends say dd.mm.yy[yy]
 305                 * is the norm there, so giving precedence to
 306                 * mm/dd/yy[yy] form only when separator is not '.'
 307                 */
 308                if (c != '.' &&
 309                    is_date(num3, num, num2, refuse_future, now, tm))
 310                        break;
 311                /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
 312                if (is_date(num3, num2, num, refuse_future, now, tm))
 313                        break;
 314                /* Funny European mm.dd.yy */
 315                if (c == '.' &&
 316                    is_date(num3, num, num2, refuse_future, now, tm))
 317                        break;
 318                return 0;
 319        }
 320        return end - date;
 321}
 322
 323/*
 324 * We've seen a digit. Time? Year? Date? 
 325 */
 326static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
 327{
 328        int n;
 329        char *end;
 330        unsigned long num;
 331
 332        num = strtoul(date, &end, 10);
 333
 334        /*
 335         * Seconds since 1970? We trigger on that for anything after Jan 1, 2000
 336         */
 337        if (num > 946684800) {
 338                time_t time = num;
 339                if (gmtime_r(&time, tm)) {
 340                        *tm_gmt = 1;
 341                        return end - date;
 342                }
 343        }
 344
 345        /*
 346         * Check for special formats: num[-.:/]num[same]num
 347         */
 348        switch (*end) {
 349        case ':':
 350        case '.':
 351        case '/':
 352        case '-':
 353                if (isdigit(end[1])) {
 354                        int match = match_multi_number(num, *end, date, end, tm);
 355                        if (match)
 356                                return match;
 357                }
 358        }
 359
 360        /*
 361         * None of the special formats? Try to guess what
 362         * the number meant. We use the number of digits
 363         * to make a more educated guess..
 364         */
 365        n = 0;
 366        do {
 367                n++;
 368        } while (isdigit(date[n]));
 369
 370        /* Four-digit year or a timezone? */
 371        if (n == 4) {
 372                if (num <= 1400 && *offset == -1) {
 373                        unsigned int minutes = num % 100;
 374                        unsigned int hours = num / 100;
 375                        *offset = hours*60 + minutes;
 376                } else if (num > 1900 && num < 2100)
 377                        tm->tm_year = num - 1900;
 378                return n;
 379        }
 380
 381        /*
 382         * NOTE! We will give precedence to day-of-month over month or
 383         * year numbers in the 1-12 range. So 05 is always "mday 5",
 384         * unless we already have a mday..
 385         *
 386         * IOW, 01 Apr 05 parses as "April 1st, 2005".
 387         */
 388        if (num > 0 && num < 32 && tm->tm_mday < 0) {
 389                tm->tm_mday = num;
 390                return n;
 391        }
 392
 393        /* Two-digit year? */
 394        if (n == 2 && tm->tm_year < 0) {
 395                if (num < 10 && tm->tm_mday >= 0) {
 396                        tm->tm_year = num + 100;
 397                        return n;
 398                }
 399                if (num >= 70) {
 400                        tm->tm_year = num;
 401                        return n;
 402                }
 403        }
 404
 405        if (num > 0 && num < 32) {
 406                tm->tm_mday = num;
 407        } else if (num > 1900) {
 408                tm->tm_year = num - 1900;
 409        } else if (num > 70) {
 410                tm->tm_year = num;
 411        } else if (num > 0 && num < 13) {
 412                tm->tm_mon = num-1;
 413        }
 414                
 415        return n;
 416}
 417
 418static int match_tz(const char *date, int *offp)
 419{
 420        char *end;
 421        int offset = strtoul(date+1, &end, 10);
 422        int min, hour;
 423        int n = end - date - 1;
 424
 425        min = offset % 100;
 426        hour = offset / 100;
 427
 428        /*
 429         * Don't accept any random crap.. At least 3 digits, and
 430         * a valid minute. We might want to check that the minutes
 431         * are divisible by 30 or something too.
 432         */
 433        if (min < 60 && n > 2) {
 434                offset = hour*60+min;
 435                if (*date == '-')
 436                        offset = -offset;
 437
 438                *offp = offset;
 439        }
 440        return end - date;
 441}
 442
 443static int date_string(unsigned long date, int offset, char *buf, int len)
 444{
 445        int sign = '+';
 446
 447        if (offset < 0) {
 448                offset = -offset;
 449                sign = '-';
 450        }
 451        return snprintf(buf, len, "%lu %c%02d%02d", date, sign, offset / 60, offset % 60);
 452}
 453
 454/* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
 455   (i.e. English) day/month names, and it doesn't work correctly with %z. */
 456int parse_date(const char *date, char *result, int maxlen)
 457{
 458        struct tm tm;
 459        int offset, tm_gmt;
 460        time_t then;
 461
 462        memset(&tm, 0, sizeof(tm));
 463        tm.tm_year = -1;
 464        tm.tm_mon = -1;
 465        tm.tm_mday = -1;
 466        tm.tm_isdst = -1;
 467        offset = -1;
 468        tm_gmt = 0;
 469
 470        for (;;) {
 471                int match = 0;
 472                unsigned char c = *date;
 473
 474                /* Stop at end of string or newline */
 475                if (!c || c == '\n')
 476                        break;
 477
 478                if (isalpha(c))
 479                        match = match_alpha(date, &tm, &offset);
 480                else if (isdigit(c))
 481                        match = match_digit(date, &tm, &offset, &tm_gmt);
 482                else if ((c == '-' || c == '+') && isdigit(date[1]))
 483                        match = match_tz(date, &offset);
 484
 485                if (!match) {
 486                        /* BAD CRAP */
 487                        match = 1;
 488                }       
 489
 490                date += match;
 491        }
 492
 493        /* mktime uses local timezone */
 494        then = my_mktime(&tm); 
 495        if (offset == -1)
 496                offset = (then - mktime(&tm)) / 60;
 497
 498        if (then == -1)
 499                return -1;
 500
 501        if (!tm_gmt)
 502                then -= offset * 60;
 503        return date_string(then, offset, result, maxlen);
 504}
 505
 506void datestamp(char *buf, int bufsize)
 507{
 508        time_t now;
 509        int offset;
 510
 511        time(&now);
 512
 513        offset = my_mktime(localtime(&now)) - now;
 514        offset /= 60;
 515
 516        date_string(now, offset, buf, bufsize);
 517}
 518
 519static void update_tm(struct tm *tm, unsigned long sec)
 520{
 521        time_t n = mktime(tm) - sec;
 522        localtime_r(&n, tm);
 523}
 524
 525static void date_yesterday(struct tm *tm, int *num)
 526{
 527        update_tm(tm, 24*60*60);
 528}
 529
 530static void date_time(struct tm *tm, int hour)
 531{
 532        if (tm->tm_hour < hour)
 533                date_yesterday(tm, NULL);
 534        tm->tm_hour = hour;
 535        tm->tm_min = 0;
 536        tm->tm_sec = 0;
 537}
 538
 539static void date_midnight(struct tm *tm, int *num)
 540{
 541        date_time(tm, 0);
 542}
 543
 544static void date_noon(struct tm *tm, int *num)
 545{
 546        date_time(tm, 12);
 547}
 548
 549static void date_tea(struct tm *tm, int *num)
 550{
 551        date_time(tm, 17);
 552}
 553
 554static const struct special {
 555        const char *name;
 556        void (*fn)(struct tm *, int *);
 557} special[] = {
 558        { "yesterday", date_yesterday },
 559        { "noon", date_noon },
 560        { "midnight", date_midnight },
 561        { "tea", date_tea },
 562        { NULL }
 563};
 564
 565static const char *number_name[] = {
 566        "zero", "one", "two", "three", "four",
 567        "five", "six", "seven", "eight", "nine", "ten",
 568};
 569
 570static const struct typelen {
 571        const char *type;
 572        int length;
 573} typelen[] = {
 574        { "seconds", 1 },
 575        { "minutes", 60 },
 576        { "hours", 60*60 },
 577        { "days", 24*60*60 },
 578        { "weeks", 7*24*60*60 },
 579        { NULL }
 580};      
 581
 582static const char *approxidate_alpha(const char *date, struct tm *tm, int *num)
 583{
 584        const struct typelen *tl;
 585        const struct special *s;
 586        const char *end = date;
 587        int i;
 588
 589        while (isalpha(*++end));
 590                ;
 591
 592        for (i = 0; i < 12; i++) {
 593                int match = match_string(date, month_names[i]);
 594                if (match >= 3) {
 595                        tm->tm_mon = i;
 596                        return end;
 597                }
 598        }
 599
 600        for (s = special; s->name; s++) {
 601                int len = strlen(s->name);
 602                if (match_string(date, s->name) == len) {
 603                        s->fn(tm, num);
 604                        return end;
 605                }
 606        }
 607
 608        if (!*num) {
 609                for (i = 1; i < 11; i++) {
 610                        int len = strlen(number_name[i]);
 611                        if (match_string(date, number_name[i]) == len) {
 612                                *num = i;
 613                                return end;
 614                        }
 615                }
 616                if (match_string(date, "last") == 4)
 617                        *num = 1;
 618                return end;
 619        }
 620
 621        tl = typelen;
 622        while (tl->type) {
 623                int len = strlen(tl->type);
 624                if (match_string(date, tl->type) >= len-1) {
 625                        update_tm(tm, tl->length * *num);
 626                        *num = 0;
 627                        return end;
 628                }
 629                tl++;
 630        }
 631
 632        for (i = 0; i < 7; i++) {
 633                int match = match_string(date, weekday_names[i]);
 634                if (match >= 3) {
 635                        int diff, n = *num -1;
 636                        *num = 0;
 637
 638                        diff = tm->tm_wday - i;
 639                        if (diff <= 0)
 640                                n++;
 641                        diff += 7*n;
 642
 643                        update_tm(tm, diff * 24 * 60 * 60);
 644                        return end;
 645                }
 646        }
 647
 648        if (match_string(date, "months") >= 5) {
 649                int n = tm->tm_mon - *num;
 650                *num = 0;
 651                while (n < 0) {
 652                        n += 12;
 653                        tm->tm_year--;
 654                }
 655                tm->tm_mon = n;
 656                return end;
 657        }
 658
 659        if (match_string(date, "years") >= 4) {
 660                tm->tm_year -= *num;
 661                *num = 0;
 662                return end;
 663        }
 664
 665        return end;
 666}
 667
 668unsigned long approxidate(const char *date)
 669{
 670        int number = 0;
 671        struct tm tm, now;
 672        struct timeval tv;
 673        char buffer[50];
 674
 675        if (parse_date(date, buffer, sizeof(buffer)) > 0)
 676                return strtoul(buffer, NULL, 10);
 677
 678        gettimeofday(&tv, NULL);
 679        localtime_r(&tv.tv_sec, &tm);
 680        now = tm;
 681        for (;;) {
 682                unsigned char c = *date;
 683                if (!c)
 684                        break;
 685                date++;
 686                if (isdigit(c)) {
 687                        char *end;
 688                        number = strtoul(date-1, &end, 10);
 689                        date = end;
 690                        continue;
 691                }
 692                if (isalpha(c))
 693                        date = approxidate_alpha(date-1, &tm, &number);
 694        }
 695        if (number > 0 && number < 32)
 696                tm.tm_mday = number;
 697        if (tm.tm_mon > now.tm_mon && tm.tm_year == now.tm_year)
 698                tm.tm_year--;
 699        return mktime(&tm);
 700}