src/date.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  */
   6
   7 #include "common.h"
   8
   9 #ifndef GIT_WIN32
  10 #include <sys/time.h>
  11 #endif
  12
  13 #include "util.h"
  14 #include "cache.h"
  15 #include "posix.h"
  16
  17 #include <ctype.h>
  18 #include <time.h>
  19
  20 typedef enum {
  21         DATE_NORMAL = 0,
  22         DATE_RELATIVE,
  23         DATE_SHORT,
  24         DATE_LOCAL,
  25         DATE_ISO8601,
  26         DATE_RFC2822,
  27         DATE_RAW
  28 } date_mode;
  29
  30 /*
  31  * This is like mktime, but without normalization of tm_wday and tm_yday.
  32  */
  33 static git_time_t tm_to_time_t(const struct tm *tm)
  34 {
  35         static const int mdays[] = {
  36             0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
  37         };
  38         int year = tm->tm_year - 70;
  39         int month = tm->tm_mon;
  40         int day = tm->tm_mday;
  41
  42         if (year < 0 || year > 129) /* algo only works for 1970-2099 */
  43                 return -1;
  44         if (month < 0 || month > 11) /* array bounds */
  45                 return -1;
  46         if (month < 2 || (year + 2) % 4)
  47                 day--;
  48         if (tm->tm_hour < 0 || tm->tm_min < 0 || tm->tm_sec < 0)
  49                 return -1;
  50         return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
  51                 tm->tm_hour * 60*60 + tm->tm_min * 60 + tm->tm_sec;
  52 }
  53
  54 static const char *month_names[] = {
  55         "January", "February", "March", "April", "May", "June",
  56         "July", "August", "September", "October", "November", "December"
  57 };
  58
  59 static const char *weekday_names[] = {
  60         "Sundays", "Mondays", "Tuesdays", "Wednesdays", "Thursdays", "Fridays", "Saturdays"
  61 };
  62
  63
  64
  65 /*
  66  * Check these. And note how it doesn't do the summer-time conversion.
  67  *
  68  * In my world, it's always summer, and things are probably a bit off
  69  * in other ways too.
  70  */
  71 static const struct {
  72         const char *name;
  73         int offset;
  74         int dst;
  75 } timezone_names[] = {
  76         { "IDLW", -12, 0, },    /* International Date Line West */
  77         { "NT",   -11, 0, },    /* Nome */
  78         { "CAT",  -10, 0, },    /* Central Alaska */
  79         { "HST",  -10, 0, },    /* Hawaii Standard */
  80         { "HDT",  -10, 1, },    /* Hawaii Daylight */
  81         { "YST",   -9, 0, },    /* Yukon Standard */
  82         { "YDT",   -9, 1, },    /* Yukon Daylight */
  83         { "PST",   -8, 0, },    /* Pacific Standard */
  84         { "PDT",   -8, 1, },    /* Pacific Daylight */
  85         { "MST",   -7, 0, },    /* Mountain Standard */
  86         { "MDT",   -7, 1, },    /* Mountain Daylight */
  87         { "CST",   -6, 0, },    /* Central Standard */
  88         { "CDT",   -6, 1, },    /* Central Daylight */
  89         { "EST",   -5, 0, },    /* Eastern Standard */
  90         { "EDT",   -5, 1, },    /* Eastern Daylight */
  91         { "AST",   -3, 0, },    /* Atlantic Standard */
  92         { "ADT",   -3, 1, },    /* Atlantic Daylight */
  93         { "WAT",   -1, 0, },    /* West Africa */
  94
  95         { "GMT",    0, 0, },    /* Greenwich Mean */
  96         { "UTC",    0, 0, },    /* Universal (Coordinated) */
  97         { "Z",      0, 0, },    /* Zulu, alias for UTC */
  98
  99         { "WET",    0, 0, },    /* Western European */
 100         { "BST",    0, 1, },    /* British Summer */
 101         { "CET",   +1, 0, },    /* Central European */
 102         { "MET",   +1, 0, },    /* Middle European */
 103         { "MEWT",  +1, 0, },    /* Middle European Winter */
 104         { "MEST",  +1, 1, },    /* Middle European Summer */
 105         { "CEST",  +1, 1, },    /* Central European Summer */
 106         { "MESZ",  +1, 1, },    /* Middle European Summer */
 107         { "FWT",   +1, 0, },    /* French Winter */
 108         { "FST",   +1, 1, },    /* French Summer */
 109         { "EET",   +2, 0, },    /* Eastern Europe */
 110         { "EEST",  +2, 1, },    /* Eastern European Daylight */
 111         { "WAST",  +7, 0, },    /* West Australian Standard */
 112         { "WADT",  +7, 1, },    /* West Australian Daylight */
 113         { "CCT",   +8, 0, },    /* China Coast */
 114         { "JST",   +9, 0, },    /* Japan Standard */
 115         { "EAST", +10, 0, },    /* Eastern Australian Standard */
 116         { "EADT", +10, 1, },    /* Eastern Australian Daylight */
 117         { "GST",  +10, 0, },    /* Guam Standard */
 118         { "NZT",  +12, 0, },    /* New Zealand */
 119         { "NZST", +12, 0, },    /* New Zealand Standard */
 120         { "NZDT", +12, 1, },    /* New Zealand Daylight */
 121         { "IDLE", +12, 0, },    /* International Date Line East */
 122 };
 123
 124 static size_t match_string(const char *date, const char *str)
 125 {
 126         size_t i = 0;
 127
 128         for (i = 0; *date; date++, str++, i++) {
 129                 if (*date == *str)
 130                         continue;
 131                 if (toupper(*date) == toupper(*str))
 132                         continue;
 133                 if (!isalnum(*date))
 134                         break;
 135                 return 0;
 136         }
 137         return i;
 138 }
 139
 140 static int skip_alpha(const char *date)
 141 {
 142         int i = 0;
 143         do {
 144                 i++;
 145         } while (isalpha(date[i]));
 146         return i;
 147 }
 148
 149 /*
 150 * Parse month, weekday, or timezone name
 151 */
 152 static size_t match_alpha(const char *date, struct tm *tm, int *offset)
 153 {
 154         unsigned int i;
 155
 156         for (i = 0; i < 12; i++) {
 157                 size_t match = match_string(date, month_names[i]);
 158                 if (match >= 3) {
 159                         tm->tm_mon = i;
 160                         return match;
 161                 }
 162         }
 163
 164         for (i = 0; i < 7; i++) {
 165                 size_t match = match_string(date, weekday_names[i]);
 166                 if (match >= 3) {
 167                         tm->tm_wday = i;
 168                         return match;
 169                 }
 170         }
 171
 172         for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
 173                 size_t match = match_string(date, timezone_names[i].name);
 174                 if (match >= 3 || match == strlen(timezone_names[i].name)) {
 175                         int off = timezone_names[i].offset;
 176
 177                         /* This is bogus, but we like summer */
 178                         off += timezone_names[i].dst;
 179
 180                         /* Only use the tz name offset if we don't have anything better */
 181                         if (*offset == -1)
 182                                 *offset = 60*off;
 183
 184                         return match;
 185                 }
 186         }
 187
 188         if (match_string(date, "PM") == 2) {
 189                 tm->tm_hour = (tm->tm_hour % 12) + 12;
 190                 return 2;
 191         }
 192
 193         if (match_string(date, "AM") == 2) {
 194                 tm->tm_hour = (tm->tm_hour % 12) + 0;
 195                 return 2;
 196         }
 197
 198         /* BAD */
 199         return skip_alpha(date);
 200 }
 201
 202 static int is_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
 203 {
 204         if (month > 0 && month < 13 && day > 0 && day < 32) {
 205                 struct tm check = *tm;
 206                 struct tm *r = (now_tm ? &check : tm);
 207                 git_time_t specified;
 208
 209                 r->tm_mon = month - 1;
 210                 r->tm_mday = day;
 211                 if (year == -1) {
 212                         if (!now_tm)
 213                                 return 1;
 214                         r->tm_year = now_tm->tm_year;
 215                 }
 216                 else if (year >= 1970 && year < 2100)
 217                         r->tm_year = year - 1900;
 218                 else if (year > 70 && year < 100)
 219                         r->tm_year = year;
 220                 else if (year < 38)
 221                         r->tm_year = year + 100;
 222                 else
 223                         return 0;
 224                 if (!now_tm)
 225                         return 1;
 226
 227                 specified = tm_to_time_t(r);
 228
 229                 /* Be it commit time or author time, it does not make
 230                  * sense to specify timestamp way into the future.  Make
 231                  * sure it is not later than ten days from now...
 232                  */
 233                 if (now + 10*24*3600 < specified)
 234                         return 0;
 235                 tm->tm_mon = r->tm_mon;
 236                 tm->tm_mday = r->tm_mday;
 237                 if (year != -1)
 238                         tm->tm_year = r->tm_year;
 239                 return 1;
 240         }
 241         return 0;
 242 }
 243
 244 static size_t match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
 245 {
 246         time_t now;
 247         struct tm now_tm;
 248         struct tm *refuse_future;
 249         long num2, num3;
 250
 251         num2 = strtol(end+1, &end, 10);
 252         num3 = -1;
 253         if (*end == c && isdigit(end[1]))
 254                 num3 = strtol(end+1, &end, 10);
 255
 256         /* Time? Date? */
 257         switch (c) {
 258         case ':':
 259                 if (num3 < 0)
 260                         num3 = 0;
 261                 if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
 262                         tm->tm_hour = num;
 263                         tm->tm_min = num2;
 264                         tm->tm_sec = num3;
 265                         break;
 266                 }
 267                 return 0;
 268
 269         case '-':
 270         case '/':
 271         case '.':
 272                 now = time(NULL);
 273                 refuse_future = NULL;
 274                 if (p_gmtime_r(&now, &now_tm))
 275                         refuse_future = &now_tm;
 276
 277                 if (num > 70) {
 278                         /* yyyy-mm-dd? */
 279                         if (is_date(num, num2, num3, refuse_future, now, tm))
 280                                 break;
 281                         /* yyyy-dd-mm? */
 282                         if (is_date(num, num3, num2, refuse_future, now, tm))
 283                                 break;
 284                 }
 285                 /* Our eastern European friends say dd.mm.yy[yy]
 286                  * is the norm there, so giving precedence to
 287                  * mm/dd/yy[yy] form only when separator is not '.'
 288                  */
 289                 if (c != '.' &&
 290                     is_date(num3, num, num2, refuse_future, now, tm))
 291                         break;
 292                 /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
 293                 if (is_date(num3, num2, num, refuse_future, now, tm))
 294                         break;
 295                 /* Funny European mm.dd.yy */
 296                 if (c == '.' &&
 297                     is_date(num3, num, num2, refuse_future, now, tm))
 298                         break;
 299                 return 0;
 300         }
 301         return end - date;
 302 }
 303
 304 /*
 305  * Have we filled in any part of the time/date yet?
 306  * We just do a binary 'and' to see if the sign bit
 307  * is set in all the values.
 308  */
 309 static int nodate(struct tm *tm)
 310 {
 311         return (tm->tm_year &
 312                 tm->tm_mon &
 313                 tm->tm_mday &
 314                 tm->tm_hour &
 315                 tm->tm_min &
 316                 tm->tm_sec) < 0;
 317 }
 318
 319 /*
 320  * We've seen a digit. Time? Year? Date?
 321  */
 322 static size_t match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
 323 {
 324         size_t n;
 325         char *end;
 326         unsigned long num;
 327
 328         num = strtoul(date, &end, 10);
 329
 330         /*
 331          * Seconds since 1970? We trigger on that for any numbers with
 332          * more than 8 digits. This is because we don't want to rule out
 333          * numbers like 20070606 as a YYYYMMDD date.
 334          */
 335         if (num >= 100000000 && nodate(tm)) {
 336                 time_t time = num;
 337                 if (p_gmtime_r(&time, tm)) {
 338                         *tm_gmt = 1;
 339                         return end - date;
 340                 }
 341         }
 342
 343         /*
 344          * Check for special formats: num[-.:/]num[same]num
 345          */
 346         switch (*end) {
 347         case ':':
 348         case '.':
 349         case '/':
 350         case '-':
 351                 if (isdigit(end[1])) {
 352                         size_t match = match_multi_number(num, *end, date, end, tm);
 353                         if (match)
 354                                 return match;
 355                 }
 356         }
 357
 358         /*
 359          * None of the special formats? Try to guess what
 360          * the number meant. We use the number of digits
 361          * to make a more educated guess..
 362          */
 363         n = 0;
 364         do {
 365                 n++;
 366         } while (isdigit(date[n]));
 367
 368         /* Four-digit year or a timezone? */
 369         if (n == 4) {
 370                 if (num <= 1400 && *offset == -1) {
 371                         unsigned int minutes = num % 100;
 372                         unsigned int hours = num / 100;
 373                         *offset = hours*60 + minutes;
 374                 } else if (num > 1900 && num < 2100)
 375                         tm->tm_year = num - 1900;
 376                 return n;
 377         }
 378
 379         /*
 380          * Ignore lots of numerals. We took care of 4-digit years above.
 381          * Days or months must be one or two digits.
 382          */
 383         if (n > 2)
 384                 return n;
 385
 386         /*
 387          * NOTE! We will give precedence to day-of-month over month or
 388          * year numbers in the 1-12 range. So 05 is always "mday 5",
 389          * unless we already have a mday..
 390          *
 391          * IOW, 01 Apr 05 parses as "April 1st, 2005".
 392          */
 393         if (num > 0 && num < 32 && tm->tm_mday < 0) {
 394                 tm->tm_mday = num;
 395                 return n;
 396         }
 397
 398         /* Two-digit year? */
 399         if (n == 2 && tm->tm_year < 0) {
 400                 if (num < 10 && tm->tm_mday >= 0) {
 401                         tm->tm_year = num + 100;
 402                         return n;
 403                 }
 404                 if (num >= 70) {
 405                         tm->tm_year = num;
 406                         return n;
 407                 }
 408         }
 409
 410         if (num > 0 && num < 13 && tm->tm_mon < 0)
 411                 tm->tm_mon = num-1;
 412
 413         return n;
 414 }
 415
 416 static size_t match_tz(const char *date, int *offp)
 417 {
 418         char *end;
 419         int hour = strtoul(date + 1, &end, 10);
 420         size_t n = end - (date + 1);
 421         int min = 0;
 422
 423         if (n == 4) {
 424                 /* hhmm */
 425                 min = hour % 100;
 426                 hour = hour / 100;
 427         } else if (n != 2) {
 428                 min = 99; /* random stuff */
 429         } else if (*end == ':') {
 430                 /* hh:mm? */
 431                 min = strtoul(end + 1, &end, 10);
 432                 if (end - (date + 1) != 5)
 433                         min = 99; /* random stuff */
 434         } /* otherwise we parsed "hh" */
 435
 436         /*
 437          * Don't accept any random stuff. Even though some places have
 438          * offset larger than 12 hours (e.g. Pacific/Kiritimati is at
 439          * UTC+14), there is something wrong if hour part is much
 440          * larger than that. We might also want to check that the
 441          * minutes are divisible by 15 or something too. (Offset of
 442          * Kathmandu, Nepal is UTC+5:45)
 443          */
 444         if (min < 60 && hour < 24) {
 445                 int offset = hour * 60 + min;
 446                 if (*date == '-')
 447                         offset = -offset;
 448                 *offp = offset;
 449         }
 450         return end - date;
 451 }
 452
 453 /*
 454  * Parse a string like "0 +0000" as ancient timestamp near epoch, but
 455  * only when it appears not as part of any other string.
 456  */
 457 static int match_object_header_date(const char *date, git_time_t *timestamp, int *offset)
 458 {
 459         char *end;
 460         unsigned long stamp;
 461         int ofs;
 462
 463         if (*date < '0' || '9' <= *date)
 464                 return -1;
 465         stamp = strtoul(date, &end, 10);
 466         if (*end != ' ' || stamp == ULONG_MAX || (end[1] != '+' && end[1] != '-'))
 467                 return -1;
 468         date = end + 2;
 469         ofs = strtol(date, &end, 10);
 470         if ((*end != '\0' && (*end != '\n')) || end != date + 4)
 471                 return -1;
 472         ofs = (ofs / 100) * 60 + (ofs % 100);
 473         if (date[-1] == '-')
 474                 ofs = -ofs;
 475         *timestamp = stamp;
 476         *offset = ofs;
 477         return 0;
 478 }
 479
 480 /* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
 481    (i.e. English) day/month names, and it doesn't work correctly with %z. */
 482 static int parse_date_basic(const char *date, git_time_t *timestamp, int *offset)
 483 {
 484         struct tm tm;
 485         int tm_gmt;
 486         git_time_t dummy_timestamp;
 487         int dummy_offset;
 488
 489         if (!timestamp)
 490                 timestamp = &dummy_timestamp;
 491         if (!offset)
 492                 offset = &dummy_offset;
 493
 494         memset(&tm, 0, sizeof(tm));
 495         tm.tm_year = -1;
 496         tm.tm_mon = -1;
 497         tm.tm_mday = -1;
 498         tm.tm_isdst = -1;
 499         tm.tm_hour = -1;
 500         tm.tm_min = -1;
 501         tm.tm_sec = -1;
 502         *offset = -1;
 503         tm_gmt = 0;
 504
 505         if (*date == '@' &&
 506             !match_object_header_date(date + 1, timestamp, offset))
 507                 return 0; /* success */
 508         for (;;) {
 509                 size_t match = 0;
 510                 unsigned char c = *date;
 511
 512                 /* Stop at end of string or newline */
 513                 if (!c || c == '\n')
 514                         break;
 515
 516                 if (isalpha(c))
 517                         match = match_alpha(date, &tm, offset);
 518                 else if (isdigit(c))
 519                         match = match_digit(date, &tm, offset, &tm_gmt);
 520                 else if ((c == '-' || c == '+') && isdigit(date[1]))
 521                         match = match_tz(date, offset);
 522
 523                 if (!match) {
 524                         /* BAD */
 525                         match = 1;
 526                 }
 527
 528                 date += match;
 529         }
 530
 531         /* mktime uses local timezone */
 532         *timestamp = tm_to_time_t(&tm);
 533         if (*offset == -1)
 534                 *offset = (int)((time_t)*timestamp - mktime(&tm)) / 60;
 535
 536         if (*timestamp == (git_time_t)-1)
 537                 return -1;
 538
 539         if (!tm_gmt)
 540                 *timestamp -= *offset * 60;
 541         return 0; /* success */
 542 }
 543
 544
 545 /*
 546  * Relative time update (eg "2 days ago").  If we haven't set the time
 547  * yet, we need to set it from current time.
 548  */
 549 static git_time_t update_tm(struct tm *tm, struct tm *now, unsigned long sec)
 550 {
 551         time_t n;
 552
 553         if (tm->tm_mday < 0)
 554                 tm->tm_mday = now->tm_mday;
 555         if (tm->tm_mon < 0)
 556                 tm->tm_mon = now->tm_mon;
 557         if (tm->tm_year < 0) {
 558                 tm->tm_year = now->tm_year;
 559                 if (tm->tm_mon > now->tm_mon)
 560                         tm->tm_year--;
 561         }
 562
 563         n = mktime(tm) - sec;
 564         p_localtime_r(&n, tm);
 565         return n;
 566 }
 567
 568 static void date_now(struct tm *tm, struct tm *now, int *num)
 569 {
 570    GIT_UNUSED(num);
 571         update_tm(tm, now, 0);
 572 }
 573
 574 static void date_yesterday(struct tm *tm, struct tm *now, int *num)
 575 {
 576    GIT_UNUSED(num);
 577         update_tm(tm, now, 24*60*60);
 578 }
 579
 580 static void date_time(struct tm *tm, struct tm *now, int hour)
 581 {
 582         if (tm->tm_hour < hour)
 583                 date_yesterday(tm, now, NULL);
 584         tm->tm_hour = hour;
 585         tm->tm_min = 0;
 586         tm->tm_sec = 0;
 587 }
 588
 589 static void date_midnight(struct tm *tm, struct tm *now, int *num)
 590 {
 591    GIT_UNUSED(num);
 592         date_time(tm, now, 0);
 593 }
 594
 595 static void date_noon(struct tm *tm, struct tm *now, int *num)
 596 {
 597    GIT_UNUSED(num);
 598         date_time(tm, now, 12);
 599 }
 600
 601 static void date_tea(struct tm *tm, struct tm *now, int *num)
 602 {
 603    GIT_UNUSED(num);
 604         date_time(tm, now, 17);
 605 }
 606
 607 static void date_pm(struct tm *tm, struct tm *now, int *num)
 608 {
 609         int hour, n = *num;
 610         *num = 0;
 611    GIT_UNUSED(now);
 612
 613         hour = tm->tm_hour;
 614         if (n) {
 615                 hour = n;
 616                 tm->tm_min = 0;
 617                 tm->tm_sec = 0;
 618         }
 619         tm->tm_hour = (hour % 12) + 12;
 620 }
 621
 622 static void date_am(struct tm *tm, struct tm *now, int *num)
 623 {
 624         int hour, n = *num;
 625         *num = 0;
 626    GIT_UNUSED(now);
 627
 628         hour = tm->tm_hour;
 629         if (n) {
 630                 hour = n;
 631                 tm->tm_min = 0;
 632                 tm->tm_sec = 0;
 633         }
 634         tm->tm_hour = (hour % 12);
 635 }
 636
 637 static void date_never(struct tm *tm, struct tm *now, int *num)
 638 {
 639         time_t n = 0;
 640    GIT_UNUSED(now);
 641    GIT_UNUSED(num);
 642         p_localtime_r(&n, tm);
 643 }
 644
 645 static const struct special {
 646         const char *name;
 647         void (*fn)(struct tm *, struct tm *, int *);
 648 } special[] = {
 649         { "yesterday", date_yesterday },
 650         { "noon", date_noon },
 651         { "midnight", date_midnight },
 652         { "tea", date_tea },
 653         { "PM", date_pm },
 654         { "AM", date_am },
 655         { "never", date_never },
 656         { "now", date_now },
 657         { NULL }
 658 };
 659
 660 static const char *number_name[] = {
 661         "zero", "one", "two", "three", "four",
 662         "five", "six", "seven", "eight", "nine", "ten",
 663 };
 664
 665 static const struct typelen {
 666         const char *type;
 667         int length;
 668 } typelen[] = {
 669         { "seconds", 1 },
 670         { "minutes", 60 },
 671         { "hours", 60*60 },
 672         { "days", 24*60*60 },
 673         { "weeks", 7*24*60*60 },
 674         { NULL }
 675 };
 676
 677 static const char *approxidate_alpha(const char *date, struct tm *tm, struct tm *now, int *num, int *touched)
 678 {
 679         const struct typelen *tl;
 680         const struct special *s;
 681         const char *end = date;
 682         int i;
 683
 684         while (isalpha(*++end))
 685                 /* scan to non-alpha */;
 686
 687         for (i = 0; i < 12; i++) {
 688                 size_t match = match_string(date, month_names[i]);
 689                 if (match >= 3) {
 690                         tm->tm_mon = i;
 691                         *touched = 1;
 692                         return end;
 693                 }
 694         }
 695
 696         for (s = special; s->name; s++) {
 697                 size_t len = strlen(s->name);
 698                 if (match_string(date, s->name) == len) {
 699                         s->fn(tm, now, num);
 700                         *touched = 1;
 701                         return end;
 702                 }
 703         }
 704
 705         if (!*num) {
 706                 for (i = 1; i < 11; i++) {
 707                         size_t len = strlen(number_name[i]);
 708                         if (match_string(date, number_name[i]) == len) {
 709                                 *num = i;
 710                                 *touched = 1;
 711                                 return end;
 712                         }
 713                 }
 714                 if (match_string(date, "last") == 4) {
 715                         *num = 1;
 716                         *touched = 1;
 717                 }
 718                 return end;
 719         }
 720
 721         tl = typelen;
 722         while (tl->type) {
 723                 size_t len = strlen(tl->type);
 724                 if (match_string(date, tl->type) >= len-1) {
 725                         update_tm(tm, now, tl->length * (unsigned long)*num);
 726                         *num = 0;
 727                         *touched = 1;
 728                         return end;
 729                 }
 730                 tl++;
 731         }
 732
 733         for (i = 0; i < 7; i++) {
 734                 size_t match = match_string(date, weekday_names[i]);
 735                 if (match >= 3) {
 736                         int diff, n = *num -1;
 737                         *num = 0;
 738
 739                         diff = tm->tm_wday - i;
 740                         if (diff <= 0)
 741                                 n++;
 742                         diff += 7*n;
 743
 744                         update_tm(tm, now, diff * 24 * 60 * 60);
 745                         *touched = 1;
 746                         return end;
 747                 }
 748         }
 749
 750         if (match_string(date, "months") >= 5) {
 751                 int n;
 752                 update_tm(tm, now, 0); /* fill in date fields if needed */
 753                 n = tm->tm_mon - *num;
 754                 *num = 0;
 755                 while (n < 0) {
 756                         n += 12;
 757                         tm->tm_year--;
 758                 }
 759                 tm->tm_mon = n;
 760                 *touched = 1;
 761                 return end;
 762         }
 763
 764         if (match_string(date, "years") >= 4) {
 765                 update_tm(tm, now, 0); /* fill in date fields if needed */
 766                 tm->tm_year -= *num;
 767                 *num = 0;
 768                 *touched = 1;
 769                 return end;
 770         }
 771
 772         return end;
 773 }
 774
 775 static const char *approxidate_digit(const char *date, struct tm *tm, int *num)
 776 {
 777         char *end;
 778         unsigned long number = strtoul(date, &end, 10);
 779
 780         switch (*end) {
 781         case ':':
 782         case '.':
 783         case '/':
 784         case '-':
 785                 if (isdigit(end[1])) {
 786                         size_t match = match_multi_number(number, *end, date, end, tm);
 787                         if (match)
 788                                 return date + match;
 789                 }
 790         }
 791
 792         /* Accept zero-padding only for small numbers ("Dec 02", never "Dec 0002") */
 793         if (date[0] != '0' || end - date <= 2)
 794                 *num = number;
 795         return end;
 796 }
 797
 798 /*
 799  * Do we have a pending number at the end, or when
 800  * we see a new one? Let's assume it's a month day,
 801  * as in "Dec 6, 1992"
 802  */
 803 static void pending_number(struct tm *tm, int *num)
 804 {
 805         int number = *num;
 806
 807         if (number) {
 808                 *num = 0;
 809                 if (tm->tm_mday < 0 && number < 32)
 810                         tm->tm_mday = number;
 811                 else if (tm->tm_mon < 0 && number < 13)
 812                         tm->tm_mon = number-1;
 813                 else if (tm->tm_year < 0) {
 814                         if (number > 1969 && number < 2100)
 815                                 tm->tm_year = number - 1900;
 816                         else if (number > 69 && number < 100)
 817                                 tm->tm_year = number;
 818                         else if (number < 38)
 819                                 tm->tm_year = 100 + number;
 820                         /* We mess up for number = 00 ? */
 821                 }
 822         }
 823 }
 824
 825 static git_time_t approxidate_str(const char *date,
 826         time_t time_sec,
 827         int *error_ret)
 828 {
 829         int number = 0;
 830         int touched = 0;
 831         struct tm tm = {0}, now;
 832
 833         p_localtime_r(&time_sec, &tm);
 834         now = tm;
 835
 836         tm.tm_year = -1;
 837         tm.tm_mon = -1;
 838         tm.tm_mday = -1;
 839
 840         for (;;) {
 841                 unsigned char c = *date;
 842                 if (!c)
 843                         break;
 844                 date++;
 845                 if (isdigit(c)) {
 846                         pending_number(&tm, &number);
 847                         date = approxidate_digit(date-1, &tm, &number);
 848                         touched = 1;
 849                         continue;
 850                 }
 851                 if (isalpha(c))
 852                         date = approxidate_alpha(date-1, &tm, &now, &number, &touched);
 853         }
 854         pending_number(&tm, &number);
 855         if (!touched)
 856                 *error_ret = 1;
 857         return update_tm(&tm, &now, 0);
 858 }
 859
 860 int git__date_parse(git_time_t *out, const char *date)
 861 {
 862         time_t time_sec;
 863         git_time_t timestamp;
 864         int offset, error_ret=0;
 865
 866         if (!parse_date_basic(date, &timestamp, &offset)) {
 867                 *out = timestamp;
 868                 return 0;
 869         }
 870
 871         if (time(&time_sec) == -1)
 872                 return -1;
 873
 874         *out = approxidate_str(date, time_sec, &error_ret);
 875    return error_ret;
 876 }
 877
 878 int git__date_rfc2822_fmt(char *out, size_t len, const git_time *date)
 879 {
 880         int written;
 881         struct tm gmt;
 882         time_t t;
 883
 884         GIT_ASSERT_ARG(out);
 885         GIT_ASSERT_ARG(date);
 886
 887         t = (time_t) (date->time + date->offset * 60);
 888
 889         if (p_gmtime_r (&t, &gmt) == NULL)
 890                 return -1;
 891
 892         written = p_snprintf(out, len, "%.3s, %u %.3s %.4u %02u:%02u:%02u %+03d%02d",
 893                 weekday_names[gmt.tm_wday],
 894                 gmt.tm_mday,
 895                 month_names[gmt.tm_mon],
 896                 gmt.tm_year + 1900,
 897                 gmt.tm_hour, gmt.tm_min, gmt.tm_sec,
 898                 date->offset / 60, date->offset % 60);
 899
 900         if (written < 0 || (written > (int) len - 1))
 901                 return -1;
 902
 903         return 0;
 904 }
 905