date.con commit diff-lib: allow ita entries treated as "not yet exist in index" (425a28e)
   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 */
  12static time_t tm_to_time_t(const struct tm *tm)
  13{
  14        static const int mdays[] = {
  15            0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
  16        };
  17        int year = tm->tm_year - 70;
  18        int month = tm->tm_mon;
  19        int day = tm->tm_mday;
  20
  21        if (year < 0 || year > 129) /* algo only works for 1970-2099 */
  22                return -1;
  23        if (month < 0 || month > 11) /* array bounds */
  24                return -1;
  25        if (month < 2 || (year + 2) % 4)
  26                day--;
  27        if (tm->tm_hour < 0 || tm->tm_min < 0 || tm->tm_sec < 0)
  28                return -1;
  29        return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
  30                tm->tm_hour * 60*60 + tm->tm_min * 60 + tm->tm_sec;
  31}
  32
  33static const char *month_names[] = {
  34        "January", "February", "March", "April", "May", "June",
  35        "July", "August", "September", "October", "November", "December"
  36};
  37
  38static const char *weekday_names[] = {
  39        "Sundays", "Mondays", "Tuesdays", "Wednesdays", "Thursdays", "Fridays", "Saturdays"
  40};
  41
  42static time_t gm_time_t(unsigned long time, int tz)
  43{
  44        int minutes;
  45
  46        minutes = tz < 0 ? -tz : tz;
  47        minutes = (minutes / 100)*60 + (minutes % 100);
  48        minutes = tz < 0 ? -minutes : minutes;
  49        return time + minutes * 60;
  50}
  51
  52/*
  53 * The "tz" thing is passed in as this strange "decimal parse of tz"
  54 * thing, which means that tz -0100 is passed in as the integer -100,
  55 * even though it means "sixty minutes off"
  56 */
  57static struct tm *time_to_tm(unsigned long time, int tz)
  58{
  59        time_t t = gm_time_t(time, tz);
  60        return gmtime(&t);
  61}
  62
  63/*
  64 * What value of "tz" was in effect back then at "time" in the
  65 * local timezone?
  66 */
  67static int local_tzoffset(unsigned long time)
  68{
  69        time_t t, t_local;
  70        struct tm tm;
  71        int offset, eastwest;
  72
  73        t = time;
  74        localtime_r(&t, &tm);
  75        t_local = tm_to_time_t(&tm);
  76
  77        if (t_local == -1)
  78                return 0; /* error; just use +0000 */
  79        if (t_local < t) {
  80                eastwest = -1;
  81                offset = t - t_local;
  82        } else {
  83                eastwest = 1;
  84                offset = t_local - t;
  85        }
  86        offset /= 60; /* in minutes */
  87        offset = (offset % 60) + ((offset / 60) * 100);
  88        return offset * eastwest;
  89}
  90
  91void show_date_relative(unsigned long time, int tz,
  92                               const struct timeval *now,
  93                               struct strbuf *timebuf)
  94{
  95        unsigned long diff;
  96        if (now->tv_sec < time) {
  97                strbuf_addstr(timebuf, _("in the future"));
  98                return;
  99        }
 100        diff = now->tv_sec - time;
 101        if (diff < 90) {
 102                strbuf_addf(timebuf,
 103                         Q_("%lu second ago", "%lu seconds ago", diff), diff);
 104                return;
 105        }
 106        /* Turn it into minutes */
 107        diff = (diff + 30) / 60;
 108        if (diff < 90) {
 109                strbuf_addf(timebuf,
 110                         Q_("%lu minute ago", "%lu minutes ago", diff), diff);
 111                return;
 112        }
 113        /* Turn it into hours */
 114        diff = (diff + 30) / 60;
 115        if (diff < 36) {
 116                strbuf_addf(timebuf,
 117                         Q_("%lu hour ago", "%lu hours ago", diff), diff);
 118                return;
 119        }
 120        /* We deal with number of days from here on */
 121        diff = (diff + 12) / 24;
 122        if (diff < 14) {
 123                strbuf_addf(timebuf,
 124                         Q_("%lu day ago", "%lu days ago", diff), diff);
 125                return;
 126        }
 127        /* Say weeks for the past 10 weeks or so */
 128        if (diff < 70) {
 129                strbuf_addf(timebuf,
 130                         Q_("%lu week ago", "%lu weeks ago", (diff + 3) / 7),
 131                         (diff + 3) / 7);
 132                return;
 133        }
 134        /* Say months for the past 12 months or so */
 135        if (diff < 365) {
 136                strbuf_addf(timebuf,
 137                         Q_("%lu month ago", "%lu months ago", (diff + 15) / 30),
 138                         (diff + 15) / 30);
 139                return;
 140        }
 141        /* Give years and months for 5 years or so */
 142        if (diff < 1825) {
 143                unsigned long totalmonths = (diff * 12 * 2 + 365) / (365 * 2);
 144                unsigned long years = totalmonths / 12;
 145                unsigned long months = totalmonths % 12;
 146                if (months) {
 147                        struct strbuf sb = STRBUF_INIT;
 148                        strbuf_addf(&sb, Q_("%lu year", "%lu years", years), years);
 149                        strbuf_addf(timebuf,
 150                                 /* TRANSLATORS: "%s" is "<n> years" */
 151                                 Q_("%s, %lu month ago", "%s, %lu months ago", months),
 152                                 sb.buf, months);
 153                        strbuf_release(&sb);
 154                } else
 155                        strbuf_addf(timebuf,
 156                                 Q_("%lu year ago", "%lu years ago", years), years);
 157                return;
 158        }
 159        /* Otherwise, just years. Centuries is probably overkill. */
 160        strbuf_addf(timebuf,
 161                 Q_("%lu year ago", "%lu years ago", (diff + 183) / 365),
 162                 (diff + 183) / 365);
 163}
 164
 165struct date_mode *date_mode_from_type(enum date_mode_type type)
 166{
 167        static struct date_mode mode;
 168        if (type == DATE_STRFTIME)
 169                die("BUG: cannot create anonymous strftime date_mode struct");
 170        mode.type = type;
 171        mode.local = 0;
 172        return &mode;
 173}
 174
 175const char *show_date(unsigned long time, int tz, const struct date_mode *mode)
 176{
 177        struct tm *tm;
 178        static struct strbuf timebuf = STRBUF_INIT;
 179
 180        if (mode->type == DATE_UNIX) {
 181                strbuf_reset(&timebuf);
 182                strbuf_addf(&timebuf, "%lu", time);
 183                return timebuf.buf;
 184        }
 185
 186        if (mode->local)
 187                tz = local_tzoffset(time);
 188
 189        if (mode->type == DATE_RAW) {
 190                strbuf_reset(&timebuf);
 191                strbuf_addf(&timebuf, "%lu %+05d", time, tz);
 192                return timebuf.buf;
 193        }
 194
 195        if (mode->type == DATE_RELATIVE) {
 196                struct timeval now;
 197
 198                strbuf_reset(&timebuf);
 199                gettimeofday(&now, NULL);
 200                show_date_relative(time, tz, &now, &timebuf);
 201                return timebuf.buf;
 202        }
 203
 204        tm = time_to_tm(time, tz);
 205        if (!tm) {
 206                tm = time_to_tm(0, 0);
 207                tz = 0;
 208        }
 209
 210        strbuf_reset(&timebuf);
 211        if (mode->type == DATE_SHORT)
 212                strbuf_addf(&timebuf, "%04d-%02d-%02d", tm->tm_year + 1900,
 213                                tm->tm_mon + 1, tm->tm_mday);
 214        else if (mode->type == DATE_ISO8601)
 215                strbuf_addf(&timebuf, "%04d-%02d-%02d %02d:%02d:%02d %+05d",
 216                                tm->tm_year + 1900,
 217                                tm->tm_mon + 1,
 218                                tm->tm_mday,
 219                                tm->tm_hour, tm->tm_min, tm->tm_sec,
 220                                tz);
 221        else if (mode->type == DATE_ISO8601_STRICT) {
 222                char sign = (tz >= 0) ? '+' : '-';
 223                tz = abs(tz);
 224                strbuf_addf(&timebuf, "%04d-%02d-%02dT%02d:%02d:%02d%c%02d:%02d",
 225                                tm->tm_year + 1900,
 226                                tm->tm_mon + 1,
 227                                tm->tm_mday,
 228                                tm->tm_hour, tm->tm_min, tm->tm_sec,
 229                                sign, tz / 100, tz % 100);
 230        } else if (mode->type == DATE_RFC2822)
 231                strbuf_addf(&timebuf, "%.3s, %d %.3s %d %02d:%02d:%02d %+05d",
 232                        weekday_names[tm->tm_wday], tm->tm_mday,
 233                        month_names[tm->tm_mon], tm->tm_year + 1900,
 234                        tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
 235        else if (mode->type == DATE_STRFTIME)
 236                strbuf_addftime(&timebuf, mode->strftime_fmt, tm);
 237        else
 238                strbuf_addf(&timebuf, "%.3s %.3s %d %02d:%02d:%02d %d%c%+05d",
 239                                weekday_names[tm->tm_wday],
 240                                month_names[tm->tm_mon],
 241                                tm->tm_mday,
 242                                tm->tm_hour, tm->tm_min, tm->tm_sec,
 243                                tm->tm_year + 1900,
 244                                mode->local ? 0 : ' ',
 245                                tz);
 246        return timebuf.buf;
 247}
 248
 249/*
 250 * Check these. And note how it doesn't do the summer-time conversion.
 251 *
 252 * In my world, it's always summer, and things are probably a bit off
 253 * in other ways too.
 254 */
 255static const struct {
 256        const char *name;
 257        int offset;
 258        int dst;
 259} timezone_names[] = {
 260        { "IDLW", -12, 0, },    /* International Date Line West */
 261        { "NT",   -11, 0, },    /* Nome */
 262        { "CAT",  -10, 0, },    /* Central Alaska */
 263        { "HST",  -10, 0, },    /* Hawaii Standard */
 264        { "HDT",  -10, 1, },    /* Hawaii Daylight */
 265        { "YST",   -9, 0, },    /* Yukon Standard */
 266        { "YDT",   -9, 1, },    /* Yukon Daylight */
 267        { "PST",   -8, 0, },    /* Pacific Standard */
 268        { "PDT",   -8, 1, },    /* Pacific Daylight */
 269        { "MST",   -7, 0, },    /* Mountain Standard */
 270        { "MDT",   -7, 1, },    /* Mountain Daylight */
 271        { "CST",   -6, 0, },    /* Central Standard */
 272        { "CDT",   -6, 1, },    /* Central Daylight */
 273        { "EST",   -5, 0, },    /* Eastern Standard */
 274        { "EDT",   -5, 1, },    /* Eastern Daylight */
 275        { "AST",   -3, 0, },    /* Atlantic Standard */
 276        { "ADT",   -3, 1, },    /* Atlantic Daylight */
 277        { "WAT",   -1, 0, },    /* West Africa */
 278
 279        { "GMT",    0, 0, },    /* Greenwich Mean */
 280        { "UTC",    0, 0, },    /* Universal (Coordinated) */
 281        { "Z",      0, 0, },    /* Zulu, alias for UTC */
 282
 283        { "WET",    0, 0, },    /* Western European */
 284        { "BST",    0, 1, },    /* British Summer */
 285        { "CET",   +1, 0, },    /* Central European */
 286        { "MET",   +1, 0, },    /* Middle European */
 287        { "MEWT",  +1, 0, },    /* Middle European Winter */
 288        { "MEST",  +1, 1, },    /* Middle European Summer */
 289        { "CEST",  +1, 1, },    /* Central European Summer */
 290        { "MESZ",  +1, 1, },    /* Middle European Summer */
 291        { "FWT",   +1, 0, },    /* French Winter */
 292        { "FST",   +1, 1, },    /* French Summer */
 293        { "EET",   +2, 0, },    /* Eastern Europe, USSR Zone 1 */
 294        { "EEST",  +2, 1, },    /* Eastern European Daylight */
 295        { "WAST",  +7, 0, },    /* West Australian Standard */
 296        { "WADT",  +7, 1, },    /* West Australian Daylight */
 297        { "CCT",   +8, 0, },    /* China Coast, USSR Zone 7 */
 298        { "JST",   +9, 0, },    /* Japan Standard, USSR Zone 8 */
 299        { "EAST", +10, 0, },    /* Eastern Australian Standard */
 300        { "EADT", +10, 1, },    /* Eastern Australian Daylight */
 301        { "GST",  +10, 0, },    /* Guam Standard, USSR Zone 9 */
 302        { "NZT",  +12, 0, },    /* New Zealand */
 303        { "NZST", +12, 0, },    /* New Zealand Standard */
 304        { "NZDT", +12, 1, },    /* New Zealand Daylight */
 305        { "IDLE", +12, 0, },    /* International Date Line East */
 306};
 307
 308static int match_string(const char *date, const char *str)
 309{
 310        int i = 0;
 311
 312        for (i = 0; *date; date++, str++, i++) {
 313                if (*date == *str)
 314                        continue;
 315                if (toupper(*date) == toupper(*str))
 316                        continue;
 317                if (!isalnum(*date))
 318                        break;
 319                return 0;
 320        }
 321        return i;
 322}
 323
 324static int skip_alpha(const char *date)
 325{
 326        int i = 0;
 327        do {
 328                i++;
 329        } while (isalpha(date[i]));
 330        return i;
 331}
 332
 333/*
 334* Parse month, weekday, or timezone name
 335*/
 336static int match_alpha(const char *date, struct tm *tm, int *offset)
 337{
 338        int i;
 339
 340        for (i = 0; i < 12; i++) {
 341                int match = match_string(date, month_names[i]);
 342                if (match >= 3) {
 343                        tm->tm_mon = i;
 344                        return match;
 345                }
 346        }
 347
 348        for (i = 0; i < 7; i++) {
 349                int match = match_string(date, weekday_names[i]);
 350                if (match >= 3) {
 351                        tm->tm_wday = i;
 352                        return match;
 353                }
 354        }
 355
 356        for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
 357                int match = match_string(date, timezone_names[i].name);
 358                if (match >= 3 || match == strlen(timezone_names[i].name)) {
 359                        int off = timezone_names[i].offset;
 360
 361                        /* This is bogus, but we like summer */
 362                        off += timezone_names[i].dst;
 363
 364                        /* Only use the tz name offset if we don't have anything better */
 365                        if (*offset == -1)
 366                                *offset = 60*off;
 367
 368                        return match;
 369                }
 370        }
 371
 372        if (match_string(date, "PM") == 2) {
 373                tm->tm_hour = (tm->tm_hour % 12) + 12;
 374                return 2;
 375        }
 376
 377        if (match_string(date, "AM") == 2) {
 378                tm->tm_hour = (tm->tm_hour % 12) + 0;
 379                return 2;
 380        }
 381
 382        /* BAD CRAP */
 383        return skip_alpha(date);
 384}
 385
 386static int is_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
 387{
 388        if (month > 0 && month < 13 && day > 0 && day < 32) {
 389                struct tm check = *tm;
 390                struct tm *r = (now_tm ? &check : tm);
 391                time_t specified;
 392
 393                r->tm_mon = month - 1;
 394                r->tm_mday = day;
 395                if (year == -1) {
 396                        if (!now_tm)
 397                                return 1;
 398                        r->tm_year = now_tm->tm_year;
 399                }
 400                else if (year >= 1970 && year < 2100)
 401                        r->tm_year = year - 1900;
 402                else if (year > 70 && year < 100)
 403                        r->tm_year = year;
 404                else if (year < 38)
 405                        r->tm_year = year + 100;
 406                else
 407                        return 0;
 408                if (!now_tm)
 409                        return 1;
 410
 411                specified = tm_to_time_t(r);
 412
 413                /* Be it commit time or author time, it does not make
 414                 * sense to specify timestamp way into the future.  Make
 415                 * sure it is not later than ten days from now...
 416                 */
 417                if ((specified != -1) && (now + 10*24*3600 < specified))
 418                        return 0;
 419                tm->tm_mon = r->tm_mon;
 420                tm->tm_mday = r->tm_mday;
 421                if (year != -1)
 422                        tm->tm_year = r->tm_year;
 423                return 1;
 424        }
 425        return 0;
 426}
 427
 428static int match_multi_number(unsigned long num, char c, const char *date,
 429                              char *end, struct tm *tm, time_t now)
 430{
 431        struct tm now_tm;
 432        struct tm *refuse_future;
 433        long num2, num3;
 434
 435        num2 = strtol(end+1, &end, 10);
 436        num3 = -1;
 437        if (*end == c && isdigit(end[1]))
 438                num3 = strtol(end+1, &end, 10);
 439
 440        /* Time? Date? */
 441        switch (c) {
 442        case ':':
 443                if (num3 < 0)
 444                        num3 = 0;
 445                if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
 446                        tm->tm_hour = num;
 447                        tm->tm_min = num2;
 448                        tm->tm_sec = num3;
 449                        break;
 450                }
 451                return 0;
 452
 453        case '-':
 454        case '/':
 455        case '.':
 456                if (!now)
 457                        now = time(NULL);
 458                refuse_future = NULL;
 459                if (gmtime_r(&now, &now_tm))
 460                        refuse_future = &now_tm;
 461
 462                if (num > 70) {
 463                        /* yyyy-mm-dd? */
 464                        if (is_date(num, num2, num3, NULL, now, tm))
 465                                break;
 466                        /* yyyy-dd-mm? */
 467                        if (is_date(num, num3, num2, NULL, now, tm))
 468                                break;
 469                }
 470                /* Our eastern European friends say dd.mm.yy[yy]
 471                 * is the norm there, so giving precedence to
 472                 * mm/dd/yy[yy] form only when separator is not '.'
 473                 */
 474                if (c != '.' &&
 475                    is_date(num3, num, num2, refuse_future, now, tm))
 476                        break;
 477                /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
 478                if (is_date(num3, num2, num, refuse_future, now, tm))
 479                        break;
 480                /* Funny European mm.dd.yy */
 481                if (c == '.' &&
 482                    is_date(num3, num, num2, refuse_future, now, tm))
 483                        break;
 484                return 0;
 485        }
 486        return end - date;
 487}
 488
 489/*
 490 * Have we filled in any part of the time/date yet?
 491 * We just do a binary 'and' to see if the sign bit
 492 * is set in all the values.
 493 */
 494static inline int nodate(struct tm *tm)
 495{
 496        return (tm->tm_year &
 497                tm->tm_mon &
 498                tm->tm_mday &
 499                tm->tm_hour &
 500                tm->tm_min &
 501                tm->tm_sec) < 0;
 502}
 503
 504/*
 505 * We've seen a digit. Time? Year? Date?
 506 */
 507static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
 508{
 509        int n;
 510        char *end;
 511        unsigned long num;
 512
 513        num = strtoul(date, &end, 10);
 514
 515        /*
 516         * Seconds since 1970? We trigger on that for any numbers with
 517         * more than 8 digits. This is because we don't want to rule out
 518         * numbers like 20070606 as a YYYYMMDD date.
 519         */
 520        if (num >= 100000000 && nodate(tm)) {
 521                time_t time = num;
 522                if (gmtime_r(&time, tm)) {
 523                        *tm_gmt = 1;
 524                        return end - date;
 525                }
 526        }
 527
 528        /*
 529         * Check for special formats: num[-.:/]num[same]num
 530         */
 531        switch (*end) {
 532        case ':':
 533        case '.':
 534        case '/':
 535        case '-':
 536                if (isdigit(end[1])) {
 537                        int match = match_multi_number(num, *end, date, end, tm, 0);
 538                        if (match)
 539                                return match;
 540                }
 541        }
 542
 543        /*
 544         * None of the special formats? Try to guess what
 545         * the number meant. We use the number of digits
 546         * to make a more educated guess..
 547         */
 548        n = 0;
 549        do {
 550                n++;
 551        } while (isdigit(date[n]));
 552
 553        /* Four-digit year or a timezone? */
 554        if (n == 4) {
 555                if (num <= 1400 && *offset == -1) {
 556                        unsigned int minutes = num % 100;
 557                        unsigned int hours = num / 100;
 558                        *offset = hours*60 + minutes;
 559                } else if (num > 1900 && num < 2100)
 560                        tm->tm_year = num - 1900;
 561                return n;
 562        }
 563
 564        /*
 565         * Ignore lots of numerals. We took care of 4-digit years above.
 566         * Days or months must be one or two digits.
 567         */
 568        if (n > 2)
 569                return n;
 570
 571        /*
 572         * NOTE! We will give precedence to day-of-month over month or
 573         * year numbers in the 1-12 range. So 05 is always "mday 5",
 574         * unless we already have a mday..
 575         *
 576         * IOW, 01 Apr 05 parses as "April 1st, 2005".
 577         */
 578        if (num > 0 && num < 32 && tm->tm_mday < 0) {
 579                tm->tm_mday = num;
 580                return n;
 581        }
 582
 583        /* Two-digit year? */
 584        if (n == 2 && tm->tm_year < 0) {
 585                if (num < 10 && tm->tm_mday >= 0) {
 586                        tm->tm_year = num + 100;
 587                        return n;
 588                }
 589                if (num >= 70) {
 590                        tm->tm_year = num;
 591                        return n;
 592                }
 593        }
 594
 595        if (num > 0 && num < 13 && tm->tm_mon < 0)
 596                tm->tm_mon = num-1;
 597
 598        return n;
 599}
 600
 601static int match_tz(const char *date, int *offp)
 602{
 603        char *end;
 604        int hour = strtoul(date + 1, &end, 10);
 605        int n = end - (date + 1);
 606        int min = 0;
 607
 608        if (n == 4) {
 609                /* hhmm */
 610                min = hour % 100;
 611                hour = hour / 100;
 612        } else if (n != 2) {
 613                min = 99; /* random crap */
 614        } else if (*end == ':') {
 615                /* hh:mm? */
 616                min = strtoul(end + 1, &end, 10);
 617                if (end - (date + 1) != 5)
 618                        min = 99; /* random crap */
 619        } /* otherwise we parsed "hh" */
 620
 621        /*
 622         * Don't accept any random crap. Even though some places have
 623         * offset larger than 12 hours (e.g. Pacific/Kiritimati is at
 624         * UTC+14), there is something wrong if hour part is much
 625         * larger than that. We might also want to check that the
 626         * minutes are divisible by 15 or something too. (Offset of
 627         * Kathmandu, Nepal is UTC+5:45)
 628         */
 629        if (min < 60 && hour < 24) {
 630                int offset = hour * 60 + min;
 631                if (*date == '-')
 632                        offset = -offset;
 633                *offp = offset;
 634        }
 635        return end - date;
 636}
 637
 638static void date_string(unsigned long date, int offset, struct strbuf *buf)
 639{
 640        int sign = '+';
 641
 642        if (offset < 0) {
 643                offset = -offset;
 644                sign = '-';
 645        }
 646        strbuf_addf(buf, "%lu %c%02d%02d", date, sign, offset / 60, offset % 60);
 647}
 648
 649/*
 650 * Parse a string like "0 +0000" as ancient timestamp near epoch, but
 651 * only when it appears not as part of any other string.
 652 */
 653static int match_object_header_date(const char *date, unsigned long *timestamp, int *offset)
 654{
 655        char *end;
 656        unsigned long stamp;
 657        int ofs;
 658
 659        if (*date < '0' || '9' < *date)
 660                return -1;
 661        stamp = strtoul(date, &end, 10);
 662        if (*end != ' ' || stamp == ULONG_MAX || (end[1] != '+' && end[1] != '-'))
 663                return -1;
 664        date = end + 2;
 665        ofs = strtol(date, &end, 10);
 666        if ((*end != '\0' && (*end != '\n')) || end != date + 4)
 667                return -1;
 668        ofs = (ofs / 100) * 60 + (ofs % 100);
 669        if (date[-1] == '-')
 670                ofs = -ofs;
 671        *timestamp = stamp;
 672        *offset = ofs;
 673        return 0;
 674}
 675
 676/* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
 677   (i.e. English) day/month names, and it doesn't work correctly with %z. */
 678int parse_date_basic(const char *date, unsigned long *timestamp, int *offset)
 679{
 680        struct tm tm;
 681        int tm_gmt;
 682        unsigned long dummy_timestamp;
 683        int dummy_offset;
 684
 685        if (!timestamp)
 686                timestamp = &dummy_timestamp;
 687        if (!offset)
 688                offset = &dummy_offset;
 689
 690        memset(&tm, 0, sizeof(tm));
 691        tm.tm_year = -1;
 692        tm.tm_mon = -1;
 693        tm.tm_mday = -1;
 694        tm.tm_isdst = -1;
 695        tm.tm_hour = -1;
 696        tm.tm_min = -1;
 697        tm.tm_sec = -1;
 698        *offset = -1;
 699        tm_gmt = 0;
 700
 701        if (*date == '@' &&
 702            !match_object_header_date(date + 1, timestamp, offset))
 703                return 0; /* success */
 704        for (;;) {
 705                int match = 0;
 706                unsigned char c = *date;
 707
 708                /* Stop at end of string or newline */
 709                if (!c || c == '\n')
 710                        break;
 711
 712                if (isalpha(c))
 713                        match = match_alpha(date, &tm, offset);
 714                else if (isdigit(c))
 715                        match = match_digit(date, &tm, offset, &tm_gmt);
 716                else if ((c == '-' || c == '+') && isdigit(date[1]))
 717                        match = match_tz(date, offset);
 718
 719                if (!match) {
 720                        /* BAD CRAP */
 721                        match = 1;
 722                }
 723
 724                date += match;
 725        }
 726
 727        /* do not use mktime(), which uses local timezone, here */
 728        *timestamp = tm_to_time_t(&tm);
 729        if (*timestamp == -1)
 730                return -1;
 731
 732        if (*offset == -1) {
 733                time_t temp_time;
 734
 735                /* gmtime_r() in match_digit() may have clobbered it */
 736                tm.tm_isdst = -1;
 737                temp_time = mktime(&tm);
 738                if ((time_t)*timestamp > temp_time) {
 739                        *offset = ((time_t)*timestamp - temp_time) / 60;
 740                } else {
 741                        *offset = -(int)((temp_time - (time_t)*timestamp) / 60);
 742                }
 743        }
 744
 745        if (!tm_gmt)
 746                *timestamp -= *offset * 60;
 747        return 0; /* success */
 748}
 749
 750int parse_expiry_date(const char *date, unsigned long *timestamp)
 751{
 752        int errors = 0;
 753
 754        if (!strcmp(date, "never") || !strcmp(date, "false"))
 755                *timestamp = 0;
 756        else if (!strcmp(date, "all") || !strcmp(date, "now"))
 757                /*
 758                 * We take over "now" here, which usually translates
 759                 * to the current timestamp.  This is because the user
 760                 * really means to expire everything she has done in
 761                 * the past, and by definition reflogs are the record
 762                 * of the past, and there is nothing from the future
 763                 * to be kept.
 764                 */
 765                *timestamp = ULONG_MAX;
 766        else
 767                *timestamp = approxidate_careful(date, &errors);
 768
 769        return errors;
 770}
 771
 772int parse_date(const char *date, struct strbuf *result)
 773{
 774        unsigned long timestamp;
 775        int offset;
 776        if (parse_date_basic(date, &timestamp, &offset))
 777                return -1;
 778        date_string(timestamp, offset, result);
 779        return 0;
 780}
 781
 782static enum date_mode_type parse_date_type(const char *format, const char **end)
 783{
 784        if (skip_prefix(format, "relative", end))
 785                return DATE_RELATIVE;
 786        if (skip_prefix(format, "iso8601-strict", end) ||
 787            skip_prefix(format, "iso-strict", end))
 788                return DATE_ISO8601_STRICT;
 789        if (skip_prefix(format, "iso8601", end) ||
 790            skip_prefix(format, "iso", end))
 791                return DATE_ISO8601;
 792        if (skip_prefix(format, "rfc2822", end) ||
 793            skip_prefix(format, "rfc", end))
 794                return DATE_RFC2822;
 795        if (skip_prefix(format, "short", end))
 796                return DATE_SHORT;
 797        if (skip_prefix(format, "default", end))
 798                return DATE_NORMAL;
 799        if (skip_prefix(format, "raw", end))
 800                return DATE_RAW;
 801        if (skip_prefix(format, "unix", end))
 802                return DATE_UNIX;
 803        if (skip_prefix(format, "format", end))
 804                return DATE_STRFTIME;
 805
 806        die("unknown date format %s", format);
 807}
 808
 809void parse_date_format(const char *format, struct date_mode *mode)
 810{
 811        const char *p;
 812
 813        /* historical alias */
 814        if (!strcmp(format, "local"))
 815                format = "default-local";
 816
 817        mode->type = parse_date_type(format, &p);
 818        mode->local = 0;
 819
 820        if (skip_prefix(p, "-local", &p))
 821                mode->local = 1;
 822
 823        if (mode->type == DATE_STRFTIME) {
 824                if (!skip_prefix(p, ":", &p))
 825                        die("date format missing colon separator: %s", format);
 826                mode->strftime_fmt = xstrdup(p);
 827        } else if (*p)
 828                die("unknown date format %s", format);
 829}
 830
 831void datestamp(struct strbuf *out)
 832{
 833        time_t now;
 834        int offset;
 835
 836        time(&now);
 837
 838        offset = tm_to_time_t(localtime(&now)) - now;
 839        offset /= 60;
 840
 841        date_string(now, offset, out);
 842}
 843
 844/*
 845 * Relative time update (eg "2 days ago").  If we haven't set the time
 846 * yet, we need to set it from current time.
 847 */
 848static unsigned long update_tm(struct tm *tm, struct tm *now, unsigned long sec)
 849{
 850        time_t n;
 851
 852        if (tm->tm_mday < 0)
 853                tm->tm_mday = now->tm_mday;
 854        if (tm->tm_mon < 0)
 855                tm->tm_mon = now->tm_mon;
 856        if (tm->tm_year < 0) {
 857                tm->tm_year = now->tm_year;
 858                if (tm->tm_mon > now->tm_mon)
 859                        tm->tm_year--;
 860        }
 861
 862        n = mktime(tm) - sec;
 863        localtime_r(&n, tm);
 864        return n;
 865}
 866
 867static void date_now(struct tm *tm, struct tm *now, int *num)
 868{
 869        update_tm(tm, now, 0);
 870}
 871
 872static void date_yesterday(struct tm *tm, struct tm *now, int *num)
 873{
 874        update_tm(tm, now, 24*60*60);
 875}
 876
 877static void date_time(struct tm *tm, struct tm *now, int hour)
 878{
 879        if (tm->tm_hour < hour)
 880                date_yesterday(tm, now, NULL);
 881        tm->tm_hour = hour;
 882        tm->tm_min = 0;
 883        tm->tm_sec = 0;
 884}
 885
 886static void date_midnight(struct tm *tm, struct tm *now, int *num)
 887{
 888        date_time(tm, now, 0);
 889}
 890
 891static void date_noon(struct tm *tm, struct tm *now, int *num)
 892{
 893        date_time(tm, now, 12);
 894}
 895
 896static void date_tea(struct tm *tm, struct tm *now, int *num)
 897{
 898        date_time(tm, now, 17);
 899}
 900
 901static void date_pm(struct tm *tm, struct tm *now, int *num)
 902{
 903        int hour, n = *num;
 904        *num = 0;
 905
 906        hour = tm->tm_hour;
 907        if (n) {
 908                hour = n;
 909                tm->tm_min = 0;
 910                tm->tm_sec = 0;
 911        }
 912        tm->tm_hour = (hour % 12) + 12;
 913}
 914
 915static void date_am(struct tm *tm, struct tm *now, int *num)
 916{
 917        int hour, n = *num;
 918        *num = 0;
 919
 920        hour = tm->tm_hour;
 921        if (n) {
 922                hour = n;
 923                tm->tm_min = 0;
 924                tm->tm_sec = 0;
 925        }
 926        tm->tm_hour = (hour % 12);
 927}
 928
 929static void date_never(struct tm *tm, struct tm *now, int *num)
 930{
 931        time_t n = 0;
 932        localtime_r(&n, tm);
 933}
 934
 935static const struct special {
 936        const char *name;
 937        void (*fn)(struct tm *, struct tm *, int *);
 938} special[] = {
 939        { "yesterday", date_yesterday },
 940        { "noon", date_noon },
 941        { "midnight", date_midnight },
 942        { "tea", date_tea },
 943        { "PM", date_pm },
 944        { "AM", date_am },
 945        { "never", date_never },
 946        { "now", date_now },
 947        { NULL }
 948};
 949
 950static const char *number_name[] = {
 951        "zero", "one", "two", "three", "four",
 952        "five", "six", "seven", "eight", "nine", "ten",
 953};
 954
 955static const struct typelen {
 956        const char *type;
 957        int length;
 958} typelen[] = {
 959        { "seconds", 1 },
 960        { "minutes", 60 },
 961        { "hours", 60*60 },
 962        { "days", 24*60*60 },
 963        { "weeks", 7*24*60*60 },
 964        { NULL }
 965};
 966
 967static const char *approxidate_alpha(const char *date, struct tm *tm, struct tm *now, int *num, int *touched)
 968{
 969        const struct typelen *tl;
 970        const struct special *s;
 971        const char *end = date;
 972        int i;
 973
 974        while (isalpha(*++end))
 975                ;
 976
 977        for (i = 0; i < 12; i++) {
 978                int match = match_string(date, month_names[i]);
 979                if (match >= 3) {
 980                        tm->tm_mon = i;
 981                        *touched = 1;
 982                        return end;
 983                }
 984        }
 985
 986        for (s = special; s->name; s++) {
 987                int len = strlen(s->name);
 988                if (match_string(date, s->name) == len) {
 989                        s->fn(tm, now, num);
 990                        *touched = 1;
 991                        return end;
 992                }
 993        }
 994
 995        if (!*num) {
 996                for (i = 1; i < 11; i++) {
 997                        int len = strlen(number_name[i]);
 998                        if (match_string(date, number_name[i]) == len) {
 999                                *num = i;
1000                                *touched = 1;
1001                                return end;
1002                        }
1003                }
1004                if (match_string(date, "last") == 4) {
1005                        *num = 1;
1006                        *touched = 1;
1007                }
1008                return end;
1009        }
1010
1011        tl = typelen;
1012        while (tl->type) {
1013                int len = strlen(tl->type);
1014                if (match_string(date, tl->type) >= len-1) {
1015                        update_tm(tm, now, tl->length * *num);
1016                        *num = 0;
1017                        *touched = 1;
1018                        return end;
1019                }
1020                tl++;
1021        }
1022
1023        for (i = 0; i < 7; i++) {
1024                int match = match_string(date, weekday_names[i]);
1025                if (match >= 3) {
1026                        int diff, n = *num -1;
1027                        *num = 0;
1028
1029                        diff = tm->tm_wday - i;
1030                        if (diff <= 0)
1031                                n++;
1032                        diff += 7*n;
1033
1034                        update_tm(tm, now, diff * 24 * 60 * 60);
1035                        *touched = 1;
1036                        return end;
1037                }
1038        }
1039
1040        if (match_string(date, "months") >= 5) {
1041                int n;
1042                update_tm(tm, now, 0); /* fill in date fields if needed */
1043                n = tm->tm_mon - *num;
1044                *num = 0;
1045                while (n < 0) {
1046                        n += 12;
1047                        tm->tm_year--;
1048                }
1049                tm->tm_mon = n;
1050                *touched = 1;
1051                return end;
1052        }
1053
1054        if (match_string(date, "years") >= 4) {
1055                update_tm(tm, now, 0); /* fill in date fields if needed */
1056                tm->tm_year -= *num;
1057                *num = 0;
1058                *touched = 1;
1059                return end;
1060        }
1061
1062        return end;
1063}
1064
1065static const char *approxidate_digit(const char *date, struct tm *tm, int *num,
1066                                     time_t now)
1067{
1068        char *end;
1069        unsigned long number = strtoul(date, &end, 10);
1070
1071        switch (*end) {
1072        case ':':
1073        case '.':
1074        case '/':
1075        case '-':
1076                if (isdigit(end[1])) {
1077                        int match = match_multi_number(number, *end, date, end,
1078                                                       tm, now);
1079                        if (match)
1080                                return date + match;
1081                }
1082        }
1083
1084        /* Accept zero-padding only for small numbers ("Dec 02", never "Dec 0002") */
1085        if (date[0] != '0' || end - date <= 2)
1086                *num = number;
1087        return end;
1088}
1089
1090/*
1091 * Do we have a pending number at the end, or when
1092 * we see a new one? Let's assume it's a month day,
1093 * as in "Dec 6, 1992"
1094 */
1095static void pending_number(struct tm *tm, int *num)
1096{
1097        int number = *num;
1098
1099        if (number) {
1100                *num = 0;
1101                if (tm->tm_mday < 0 && number < 32)
1102                        tm->tm_mday = number;
1103                else if (tm->tm_mon < 0 && number < 13)
1104                        tm->tm_mon = number-1;
1105                else if (tm->tm_year < 0) {
1106                        if (number > 1969 && number < 2100)
1107                                tm->tm_year = number - 1900;
1108                        else if (number > 69 && number < 100)
1109                                tm->tm_year = number;
1110                        else if (number < 38)
1111                                tm->tm_year = 100 + number;
1112                        /* We screw up for number = 00 ? */
1113                }
1114        }
1115}
1116
1117static unsigned long approxidate_str(const char *date,
1118                                     const struct timeval *tv,
1119                                     int *error_ret)
1120{
1121        int number = 0;
1122        int touched = 0;
1123        struct tm tm, now;
1124        time_t time_sec;
1125
1126        time_sec = tv->tv_sec;
1127        localtime_r(&time_sec, &tm);
1128        now = tm;
1129
1130        tm.tm_year = -1;
1131        tm.tm_mon = -1;
1132        tm.tm_mday = -1;
1133
1134        for (;;) {
1135                unsigned char c = *date;
1136                if (!c)
1137                        break;
1138                date++;
1139                if (isdigit(c)) {
1140                        pending_number(&tm, &number);
1141                        date = approxidate_digit(date-1, &tm, &number, time_sec);
1142                        touched = 1;
1143                        continue;
1144                }
1145                if (isalpha(c))
1146                        date = approxidate_alpha(date-1, &tm, &now, &number, &touched);
1147        }
1148        pending_number(&tm, &number);
1149        if (!touched)
1150                *error_ret = 1;
1151        return update_tm(&tm, &now, 0);
1152}
1153
1154unsigned long approxidate_relative(const char *date, const struct timeval *tv)
1155{
1156        unsigned long timestamp;
1157        int offset;
1158        int errors = 0;
1159
1160        if (!parse_date_basic(date, &timestamp, &offset))
1161                return timestamp;
1162        return approxidate_str(date, tv, &errors);
1163}
1164
1165unsigned long approxidate_careful(const char *date, int *error_ret)
1166{
1167        struct timeval tv;
1168        unsigned long timestamp;
1169        int offset;
1170        int dummy = 0;
1171        if (!error_ret)
1172                error_ret = &dummy;
1173
1174        if (!parse_date_basic(date, &timestamp, &offset)) {
1175                *error_ret = 0;
1176                return timestamp;
1177        }
1178
1179        gettimeofday(&tv, NULL);
1180        return approxidate_str(date, &tv, error_ret);
1181}
1182
1183int date_overflows(unsigned long t)
1184{
1185        time_t sys;
1186
1187        /* If we overflowed our unsigned long, that's bad... */
1188        if (t == ULONG_MAX)
1189                return 1;
1190
1191        /*
1192         * ...but we also are going to feed the result to system
1193         * functions that expect time_t, which is often "signed long".
1194         * Make sure that we fit into time_t, as well.
1195         */
1196        sys = t;
1197        return t != sys || (t < 1) != (sys < 1);
1198}