Andrew's git / gitweb.git / date.c
?
date.con commit Merge branch 'jc/cache-tree' into next (dc844aa)
   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
 126static int match_string(const char *date, const char *str)
 127{
 128        int i = 0;
 129
 130        for (i = 0; *date; date++, str++, i++) {
 131                if (*date == *str)
 132                        continue;
 133                if (toupper(*date) == toupper(*str))
 134                        continue;
 135                if (!isalnum(*date))
 136                        break;
 137                return 0;
 138        }
 139        return i;
 140}
 141
 142static int skip_alpha(const char *date)
 143{
 144        int i = 0;
 145        do {
 146                i++;
 147        } while (isalpha(date[i]));
 148        return i;
 149}
 150
 151/*
 152* Parse month, weekday, or timezone name
 153*/
 154static int match_alpha(const char *date, struct tm *tm, int *offset)
 155{
 156        int i;
 157
 158        for (i = 0; i < 12; i++) {
 159                int match = match_string(date, month_names[i]);
 160                if (match >= 3) {
 161                        tm->tm_mon = i;
 162                        return match;
 163                }
 164        }
 165
 166        for (i = 0; i < 7; i++) {
 167                int match = match_string(date, weekday_names[i]);
 168                if (match >= 3) {
 169                        tm->tm_wday = i;
 170                        return match;
 171                }
 172        }
 173
 174        for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
 175                int match = match_string(date, timezone_names[i].name);
 176                if (match >= 3) {
 177                        int off = timezone_names[i].offset;
 178
 179                        /* This is bogus, but we like summer */
 180                        off += timezone_names[i].dst;
 181
 182                        /* Only use the tz name offset if we don't have anything better */
 183                        if (*offset == -1)
 184                                *offset = 60*off;
 185
 186                        return match;
 187                }
 188        }
 189
 190        if (match_string(date, "PM") == 2) {
 191                if (tm->tm_hour > 0 && tm->tm_hour < 12)
 192                        tm->tm_hour += 12;
 193                return 2;
 194        }
 195
 196        /* BAD CRAP */
 197        return skip_alpha(date);
 198}
 199
 200static int is_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
 201{
 202        if (month > 0 && month < 13 && day > 0 && day < 32) {
 203                struct tm check = *tm;
 204                struct tm *r = (now_tm ? &check : tm);
 205                time_t specified;
 206
 207                r->tm_mon = month - 1;
 208                r->tm_mday = day;
 209                if (year == -1) {
 210                        if (!now_tm)
 211                                return 1;
 212                        r->tm_year = now_tm->tm_year;
 213                }
 214                else if (year >= 1970 && year < 2100)
 215                        r->tm_year = year - 1900;
 216                else if (year > 70 && year < 100)
 217                        r->tm_year = year;
 218                else if (year < 38)
 219                        r->tm_year = year + 100;
 220                else
 221                        return 0;
 222                if (!now_tm)
 223                        return 1;
 224
 225                specified = my_mktime(r);
 226
 227                /* Be it commit time or author time, it does not make
 228                 * sense to specify timestamp way into the future.  Make
 229                 * sure it is not later than ten days from now...
 230                 */
 231                if (now + 10*24*3600 < specified)
 232                        return 0;
 233                tm->tm_mon = r->tm_mon;
 234                tm->tm_mday = r->tm_mday;
 235                if (year != -1)
 236                        tm->tm_year = r->tm_year;
 237                return 1;
 238        }
 239        return 0;
 240}
 241
 242static int match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
 243{
 244        time_t now;
 245        struct tm now_tm;
 246        struct tm *refuse_future;
 247        long num2, num3;
 248
 249        num2 = strtol(end+1, &end, 10);
 250        num3 = -1;
 251        if (*end == c && isdigit(end[1]))
 252                num3 = strtol(end+1, &end, 10);
 253
 254        /* Time? Date? */
 255        switch (c) {
 256        case ':':
 257                if (num3 < 0)
 258                        num3 = 0;
 259                if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
 260                        tm->tm_hour = num;
 261                        tm->tm_min = num2;
 262                        tm->tm_sec = num3;
 263                        break;
 264                }
 265                return 0;
 266
 267        case '-':
 268        case '/':
 269        case '.':
 270                now = time(NULL);
 271                refuse_future = NULL;
 272                if (gmtime_r(&now, &now_tm))
 273                        refuse_future = &now_tm;
 274
 275                if (num > 70) {
 276                        /* yyyy-mm-dd? */
 277                        if (is_date(num, num2, num3, refuse_future, now, tm))
 278                                break;
 279                        /* yyyy-dd-mm? */
 280                        if (is_date(num, num3, num2, refuse_future, now, tm))
 281                                break;
 282                }
 283                /* Our eastern European friends say dd.mm.yy[yy]
 284                 * is the norm there, so giving precedence to
 285                 * mm/dd/yy[yy] form only when separator is not '.'
 286                 */
 287                if (c != '.' &&
 288                    is_date(num3, num, num2, refuse_future, now, tm))
 289                        break;
 290                /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
 291                if (is_date(num3, num2, num, refuse_future, now, tm))
 292                        break;
 293                /* Funny European mm.dd.yy */
 294                if (c == '.' &&
 295                    is_date(num3, num, num2, refuse_future, now, tm))
 296                        break;
 297                return 0;
 298        }
 299        return end - date;
 300}
 301
 302/*
 303 * We've seen a digit. Time? Year? Date? 
 304 */
 305static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
 306{
 307        int n;
 308        char *end;
 309        unsigned long num;
 310
 311        num = strtoul(date, &end, 10);
 312
 313        /*
 314         * Seconds since 1970? We trigger on that for anything after Jan 1, 2000
 315         */
 316        if (num > 946684800) {
 317                time_t time = num;
 318                if (gmtime_r(&time, tm)) {
 319                        *tm_gmt = 1;
 320                        return end - date;
 321                }
 322        }
 323
 324        /*
 325         * Check for special formats: num[-.:/]num[same]num
 326         */
 327        switch (*end) {
 328        case ':':
 329        case '.':
 330        case '/':
 331        case '-':
 332                if (isdigit(end[1])) {
 333                        int match = match_multi_number(num, *end, date, end, tm);
 334                        if (match)
 335                                return match;
 336                }
 337        }
 338
 339        /*
 340         * None of the special formats? Try to guess what
 341         * the number meant. We use the number of digits
 342         * to make a more educated guess..
 343         */
 344        n = 0;
 345        do {
 346                n++;
 347        } while (isdigit(date[n]));
 348
 349        /* Four-digit year or a timezone? */
 350        if (n == 4) {
 351                if (num <= 1200 && *offset == -1) {
 352                        unsigned int minutes = num % 100;
 353                        unsigned int hours = num / 100;
 354                        *offset = hours*60 + minutes;
 355                } else if (num > 1900 && num < 2100)
 356                        tm->tm_year = num - 1900;
 357                return n;
 358        }
 359
 360        /*
 361         * NOTE! We will give precedence to day-of-month over month or
 362         * year numbers in the 1-12 range. So 05 is always "mday 5",
 363         * unless we already have a mday..
 364         *
 365         * IOW, 01 Apr 05 parses as "April 1st, 2005".
 366         */
 367        if (num > 0 && num < 32 && tm->tm_mday < 0) {
 368                tm->tm_mday = num;
 369                return n;
 370        }
 371
 372        /* Two-digit year? */
 373        if (n == 2 && tm->tm_year < 0) {
 374                if (num < 10 && tm->tm_mday >= 0) {
 375                        tm->tm_year = num + 100;
 376                        return n;
 377                }
 378                if (num >= 70) {
 379                        tm->tm_year = num;
 380                        return n;
 381                }
 382        }
 383
 384        if (num > 0 && num < 32) {
 385                tm->tm_mday = num;
 386        } else if (num > 1900) {
 387                tm->tm_year = num - 1900;
 388        } else if (num > 70) {
 389                tm->tm_year = num;
 390        } else if (num > 0 && num < 13) {
 391                tm->tm_mon = num-1;
 392        }
 393                
 394        return n;
 395}
 396
 397static int match_tz(const char *date, int *offp)
 398{
 399        char *end;
 400        int offset = strtoul(date+1, &end, 10);
 401        int min, hour;
 402        int n = end - date - 1;
 403
 404        min = offset % 100;
 405        hour = offset / 100;
 406
 407        /*
 408         * Don't accept any random crap.. At least 3 digits, and
 409         * a valid minute. We might want to check that the minutes
 410         * are divisible by 30 or something too.
 411         */
 412        if (min < 60 && n > 2) {
 413                offset = hour*60+min;
 414                if (*date == '-')
 415                        offset = -offset;
 416
 417                *offp = offset;
 418        }
 419        return end - date;
 420}
 421
 422static int date_string(unsigned long date, int offset, char *buf, int len)
 423{
 424        int sign = '+';
 425
 426        if (offset < 0) {
 427                offset = -offset;
 428                sign = '-';
 429        }
 430        return snprintf(buf, len, "%lu %c%02d%02d", date, sign, offset / 60, offset % 60);
 431}
 432
 433/* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
 434   (i.e. English) day/month names, and it doesn't work correctly with %z. */
 435int parse_date(const char *date, char *result, int maxlen)
 436{
 437        struct tm tm;
 438        int offset, tm_gmt;
 439        time_t then;
 440
 441        memset(&tm, 0, sizeof(tm));
 442        tm.tm_year = -1;
 443        tm.tm_mon = -1;
 444        tm.tm_mday = -1;
 445        tm.tm_isdst = -1;
 446        offset = -1;
 447        tm_gmt = 0;
 448
 449        for (;;) {
 450                int match = 0;
 451                unsigned char c = *date;
 452
 453                /* Stop at end of string or newline */
 454                if (!c || c == '\n')
 455                        break;
 456
 457                if (isalpha(c))
 458                        match = match_alpha(date, &tm, &offset);
 459                else if (isdigit(c))
 460                        match = match_digit(date, &tm, &offset, &tm_gmt);
 461                else if ((c == '-' || c == '+') && isdigit(date[1]))
 462                        match = match_tz(date, &offset);
 463
 464                if (!match) {
 465                        /* BAD CRAP */
 466                        match = 1;
 467                }       
 468
 469                date += match;
 470        }
 471
 472        /* mktime uses local timezone */
 473        then = my_mktime(&tm); 
 474        if (offset == -1)
 475                offset = (then - mktime(&tm)) / 60;
 476
 477        if (then == -1)
 478                return -1;
 479
 480        if (!tm_gmt)
 481                then -= offset * 60;
 482        return date_string(then, offset, result, maxlen);
 483}
 484
 485void datestamp(char *buf, int bufsize)
 486{
 487        time_t now;
 488        int offset;
 489
 490        time(&now);
 491
 492        offset = my_mktime(localtime(&now)) - now;
 493        offset /= 60;
 494
 495        date_string(now, offset, buf, bufsize);
 496}
 497
 498static void update_tm(struct tm *tm, unsigned long sec)
 499{
 500        time_t n = mktime(tm) - sec;
 501        localtime_r(&n, tm);
 502}
 503
 504static void date_yesterday(struct tm *tm, int *num)
 505{
 506        update_tm(tm, 24*60*60);
 507}
 508
 509static void date_time(struct tm *tm, int hour)
 510{
 511        if (tm->tm_hour < hour)
 512                date_yesterday(tm, NULL);
 513        tm->tm_hour = hour;
 514        tm->tm_min = 0;
 515        tm->tm_sec = 0;
 516}
 517
 518static void date_midnight(struct tm *tm, int *num)
 519{
 520        date_time(tm, 0);
 521}
 522
 523static void date_noon(struct tm *tm, int *num)
 524{
 525        date_time(tm, 12);
 526}
 527
 528static void date_tea(struct tm *tm, int *num)
 529{
 530        date_time(tm, 17);
 531}
 532
 533static const struct special {
 534        const char *name;
 535        void (*fn)(struct tm *, int *);
 536} special[] = {
 537        { "yesterday", date_yesterday },
 538        { "noon", date_noon },
 539        { "midnight", date_midnight },
 540        { "tea", date_tea },
 541        { NULL }
 542};
 543
 544static const char *number_name[] = {
 545        "zero", "one", "two", "three", "four",
 546        "five", "six", "seven", "eight", "nine", "ten",
 547};
 548
 549static const struct typelen {
 550        const char *type;
 551        int length;
 552} typelen[] = {
 553        { "seconds", 1 },
 554        { "minutes", 60 },
 555        { "hours", 60*60 },
 556        { "days", 24*60*60 },
 557        { "weeks", 7*24*60*60 },
 558        { NULL }
 559};      
 560
 561static const char *approxidate_alpha(const char *date, struct tm *tm, int *num)
 562{
 563        const struct typelen *tl;
 564        const struct special *s;
 565        const char *end = date;
 566        int n = 1, i;
 567
 568        while (isalpha(*++end))
 569                n++;
 570
 571        for (i = 0; i < 12; i++) {
 572                int match = match_string(date, month_names[i]);
 573                if (match >= 3) {
 574                        tm->tm_mon = i;
 575                        return end;
 576                }
 577        }
 578
 579        for (s = special; s->name; s++) {
 580                int len = strlen(s->name);
 581                if (match_string(date, s->name) == len) {
 582                        s->fn(tm, num);
 583                        return end;
 584                }
 585        }
 586
 587        if (!*num) {
 588                for (i = 1; i < 11; i++) {
 589                        int len = strlen(number_name[i]);
 590                        if (match_string(date, number_name[i]) == len) {
 591                                *num = i;
 592                                return end;
 593                        }
 594                }
 595                if (match_string(date, "last") == 4)
 596                        *num = 1;
 597                return end;
 598        }
 599
 600        tl = typelen;
 601        while (tl->type) {
 602                int len = strlen(tl->type);
 603                if (match_string(date, tl->type) >= len-1) {
 604                        update_tm(tm, tl->length * *num);
 605                        *num = 0;
 606                        return end;
 607                }
 608                tl++;
 609        }
 610
 611        for (i = 0; i < 7; i++) {
 612                int match = match_string(date, weekday_names[i]);
 613                if (match >= 3) {
 614                        int diff, n = *num -1;
 615                        *num = 0;
 616
 617                        diff = tm->tm_wday - i;
 618                        if (diff <= 0)
 619                                n++;
 620                        diff += 7*n;
 621
 622                        update_tm(tm, diff * 24 * 60 * 60);
 623                        return end;
 624                }
 625        }
 626
 627        if (match_string(date, "months") >= 5) {
 628                int n = tm->tm_mon - *num;
 629                *num = 0;
 630                while (n < 0) {
 631                        n += 12;
 632                        tm->tm_year--;
 633                }
 634                tm->tm_mon = n;
 635                return end;
 636        }
 637
 638        if (match_string(date, "years") >= 4) {
 639                tm->tm_year -= *num;
 640                *num = 0;
 641                return end;
 642        }
 643
 644        return end;
 645}
 646
 647unsigned long approxidate(const char *date)
 648{
 649        int number = 0;
 650        struct tm tm, now;
 651        struct timeval tv;
 652        char buffer[50];
 653
 654        if (parse_date(date, buffer, sizeof(buffer)) > 0)
 655                return strtoul(buffer, NULL, 10);
 656
 657        gettimeofday(&tv, NULL);
 658        localtime_r(&tv.tv_sec, &tm);
 659        now = tm;
 660        for (;;) {
 661                unsigned char c = *date;
 662                if (!c)
 663                        break;
 664                date++;
 665                if (isdigit(c)) {
 666                        char *end;
 667                        number = strtoul(date-1, &end, 10);
 668                        date = end;
 669                        continue;
 670                }
 671                if (isalpha(c))
 672                        date = approxidate_alpha(date-1, &tm, &number);
 673        }
 674        if (number > 0 && number < 32)
 675                tm.tm_mday = number;
 676        if (tm.tm_mon > now.tm_mon && tm.tm_year == now.tm_year)
 677                tm.tm_year--;
 678        return mktime(&tm);
 679}