date.c

   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
  12 static 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
  31 static const char *month_names[] = {
  32         "January", "February", "March", "April", "May", "June",
  33         "July", "August", "September", "October", "November", "December"
  34 };
  35
  36 static 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  */
  45 static struct tm *time_to_tm(unsigned long time, int tz)
  46 {
  47         time_t t;
  48         int minutes;
  49
  50         minutes = tz < 0 ? -tz : tz;
  51         minutes = (minutes / 100)*60 + (minutes % 100);
  52         minutes = tz < 0 ? -minutes : minutes;
  53         t = time + minutes * 60;
  54         return gmtime(&t);
  55 }
  56
  57 const char *show_date(unsigned long time, int tz)
  58 {
  59         struct tm *tm;
  60         static char timebuf[200];
  61
  62         tm = time_to_tm(time, tz);
  63         if (!tm)
  64                 return NULL;
  65         sprintf(timebuf, "%.3s %.3s %d %02d:%02d:%02d %d %+05d",
  66                 weekday_names[tm->tm_wday],
  67                 month_names[tm->tm_mon],
  68                 tm->tm_mday,
  69                 tm->tm_hour, tm->tm_min, tm->tm_sec,
  70                 tm->tm_year + 1900, tz);
  71         return timebuf;
  72 }
  73
  74 const char *show_rfc2822_date(unsigned long time, int tz)
  75 {
  76         struct tm *tm;
  77         static char timebuf[200];
  78
  79         tm = time_to_tm(time, tz);
  80         if (!tm)
  81                 return NULL;
  82         sprintf(timebuf, "%.3s, %d %.3s %d %02d:%02d:%02d %+05d",
  83                 weekday_names[tm->tm_wday], tm->tm_mday,
  84                 month_names[tm->tm_mon], tm->tm_year + 1900,
  85                 tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
  86         return timebuf;
  87 }
  88
  89 /*
  90  * Check these. And note how it doesn't do the summer-time conversion.
  91  *
  92  * In my world, it's always summer, and things are probably a bit off
  93  * in other ways too.
  94  */
  95 static const struct {
  96         const char *name;
  97         int offset;
  98         int dst;
  99 } timezone_names[] = {
 100         { "IDLW", -12, 0, },    /* International Date Line West */
 101         { "NT",   -11, 0, },    /* Nome */
 102         { "CAT",  -10, 0, },    /* Central Alaska */
 103         { "HST",  -10, 0, },    /* Hawaii Standard */
 104         { "HDT",  -10, 1, },    /* Hawaii Daylight */
 105         { "YST",   -9, 0, },    /* Yukon Standard */
 106         { "YDT",   -9, 1, },    /* Yukon Daylight */
 107         { "PST",   -8, 0, },    /* Pacific Standard */
 108         { "PDT",   -8, 1, },    /* Pacific Daylight */
 109         { "MST",   -7, 0, },    /* Mountain Standard */
 110         { "MDT",   -7, 1, },    /* Mountain Daylight */
 111         { "CST",   -6, 0, },    /* Central Standard */
 112         { "CDT",   -6, 1, },    /* Central Daylight */
 113         { "EST",   -5, 0, },    /* Eastern Standard */
 114         { "EDT",   -5, 1, },    /* Eastern Daylight */
 115         { "AST",   -3, 0, },    /* Atlantic Standard */
 116         { "ADT",   -3, 1, },    /* Atlantic Daylight */
 117         { "WAT",   -1, 0, },    /* West Africa */
 118
 119         { "GMT",    0, 0, },    /* Greenwich Mean */
 120         { "UTC",    0, 0, },    /* Universal (Coordinated) */
 121
 122         { "WET",    0, 0, },    /* Western European */
 123         { "BST",    0, 1, },    /* British Summer */
 124         { "CET",   +1, 0, },    /* Central European */
 125         { "MET",   +1, 0, },    /* Middle European */
 126         { "MEWT",  +1, 0, },    /* Middle European Winter */
 127         { "MEST",  +1, 1, },    /* Middle European Summer */
 128         { "CEST",  +1, 1, },    /* Central European Summer */
 129         { "MESZ",  +1, 1, },    /* Middle European Summer */
 130         { "FWT",   +1, 0, },    /* French Winter */
 131         { "FST",   +1, 1, },    /* French Summer */
 132         { "EET",   +2, 0, },    /* Eastern Europe, USSR Zone 1 */
 133         { "EEST",  +2, 1, },    /* Eastern European Daylight */
 134         { "WAST",  +7, 0, },    /* West Australian Standard */
 135         { "WADT",  +7, 1, },    /* West Australian Daylight */
 136         { "CCT",   +8, 0, },    /* China Coast, USSR Zone 7 */
 137         { "JST",   +9, 0, },    /* Japan Standard, USSR Zone 8 */
 138         { "EAST", +10, 0, },    /* Eastern Australian Standard */
 139         { "EADT", +10, 1, },    /* Eastern Australian Daylight */
 140         { "GST",  +10, 0, },    /* Guam Standard, USSR Zone 9 */
 141         { "NZT",  +11, 0, },    /* New Zealand */
 142         { "NZST", +11, 0, },    /* New Zealand Standard */
 143         { "NZDT", +11, 1, },    /* New Zealand Daylight */
 144         { "IDLE", +12, 0, },    /* International Date Line East */
 145 };
 146
 147 static int match_string(const char *date, const char *str)
 148 {
 149         int i = 0;
 150
 151         for (i = 0; *date; date++, str++, i++) {
 152                 if (*date == *str)
 153                         continue;
 154                 if (toupper(*date) == toupper(*str))
 155                         continue;
 156                 if (!isalnum(*date))
 157                         break;
 158                 return 0;
 159         }
 160         return i;
 161 }
 162
 163 static int skip_alpha(const char *date)
 164 {
 165         int i = 0;
 166         do {
 167                 i++;
 168         } while (isalpha(date[i]));
 169         return i;
 170 }
 171
 172 /*
 173 * Parse month, weekday, or timezone name
 174 */
 175 static int match_alpha(const char *date, struct tm *tm, int *offset)
 176 {
 177         int i;
 178
 179         for (i = 0; i < 12; i++) {
 180                 int match = match_string(date, month_names[i]);
 181                 if (match >= 3) {
 182                         tm->tm_mon = i;
 183                         return match;
 184                 }
 185         }
 186
 187         for (i = 0; i < 7; i++) {
 188                 int match = match_string(date, weekday_names[i]);
 189                 if (match >= 3) {
 190                         tm->tm_wday = i;
 191                         return match;
 192                 }
 193         }
 194
 195         for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
 196                 int match = match_string(date, timezone_names[i].name);
 197                 if (match >= 3) {
 198                         int off = timezone_names[i].offset;
 199
 200                         /* This is bogus, but we like summer */
 201                         off += timezone_names[i].dst;
 202
 203                         /* Only use the tz name offset if we don't have anything better */
 204                         if (*offset == -1)
 205                                 *offset = 60*off;
 206
 207                         return match;
 208                 }
 209         }
 210
 211         if (match_string(date, "PM") == 2) {
 212                 if (tm->tm_hour > 0 && tm->tm_hour < 12)
 213                         tm->tm_hour += 12;
 214                 return 2;
 215         }
 216
 217         /* BAD CRAP */
 218         return skip_alpha(date);
 219 }
 220
 221 static int is_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
 222 {
 223         if (month > 0 && month < 13 && day > 0 && day < 32) {
 224                 struct tm check = *tm;
 225                 struct tm *r = (now_tm ? &check : tm);
 226                 time_t specified;
 227
 228                 r->tm_mon = month - 1;
 229                 r->tm_mday = day;
 230                 if (year == -1) {
 231                         if (!now_tm)
 232                                 return 1;
 233                         r->tm_year = now_tm->tm_year;
 234                 }
 235                 else if (year >= 1970 && year < 2100)
 236                         r->tm_year = year - 1900;
 237                 else if (year > 70 && year < 100)
 238                         r->tm_year = year;
 239                 else if (year < 38)
 240                         r->tm_year = year + 100;
 241                 else
 242                         return 0;
 243                 if (!now_tm)
 244                         return 1;
 245
 246                 specified = my_mktime(r);
 247
 248                 /* Be it commit time or author time, it does not make
 249                  * sense to specify timestamp way into the future.  Make
 250                  * sure it is not later than ten days from now...
 251                  */
 252                 if (now + 10*24*3600 < specified)
 253                         return 0;
 254                 tm->tm_mon = r->tm_mon;
 255                 tm->tm_mday = r->tm_mday;
 256                 if (year != -1)
 257                         tm->tm_year = r->tm_year;
 258                 return 1;
 259         }
 260         return 0;
 261 }
 262
 263 static int match_multi_number(unsigned long num, char c, const char *date, char *end, struct tm *tm)
 264 {
 265         time_t now;
 266         struct tm now_tm;
 267         struct tm *refuse_future;
 268         long num2, num3;
 269
 270         num2 = strtol(end+1, &end, 10);
 271         num3 = -1;
 272         if (*end == c && isdigit(end[1]))
 273                 num3 = strtol(end+1, &end, 10);
 274
 275         /* Time? Date? */
 276         switch (c) {
 277         case ':':
 278                 if (num3 < 0)
 279                         num3 = 0;
 280                 if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
 281                         tm->tm_hour = num;
 282                         tm->tm_min = num2;
 283                         tm->tm_sec = num3;
 284                         break;
 285                 }
 286                 return 0;
 287
 288         case '-':
 289         case '/':
 290         case '.':
 291                 now = time(NULL);
 292                 refuse_future = NULL;
 293                 if (gmtime_r(&now, &now_tm))
 294                         refuse_future = &now_tm;
 295
 296                 if (num > 70) {
 297                         /* yyyy-mm-dd? */
 298                         if (is_date(num, num2, num3, refuse_future, now, tm))
 299                                 break;
 300                         /* yyyy-dd-mm? */
 301                         if (is_date(num, num3, num2, refuse_future, now, tm))
 302                                 break;
 303                 }
 304                 /* Our eastern European friends say dd.mm.yy[yy]
 305                  * is the norm there, so giving precedence to
 306                  * mm/dd/yy[yy] form only when separator is not '.'
 307                  */
 308                 if (c != '.' &&
 309                     is_date(num3, num, num2, refuse_future, now, tm))
 310                         break;
 311                 /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
 312                 if (is_date(num3, num2, num, refuse_future, now, tm))
 313                         break;
 314                 /* Funny European mm.dd.yy */
 315                 if (c == '.' &&
 316                     is_date(num3, num, num2, refuse_future, now, tm))
 317                         break;
 318                 return 0;
 319         }
 320         return end - date;
 321 }
 322
 323 /*
 324  * We've seen a digit. Time? Year? Date?
 325  */
 326 static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
 327 {
 328         int n;
 329         char *end;
 330         unsigned long num;
 331
 332         num = strtoul(date, &end, 10);
 333
 334         /*
 335          * Seconds since 1970? We trigger on that for anything after Jan 1, 2000
 336          */
 337         if (num > 946684800) {
 338                 time_t time = num;
 339                 if (gmtime_r(&time, tm)) {
 340                         *tm_gmt = 1;
 341                         return end - date;
 342                 }
 343         }
 344
 345         /*
 346          * Check for special formats: num[-.:/]num[same]num
 347          */
 348         switch (*end) {
 349         case ':':
 350         case '.':
 351         case '/':
 352         case '-':
 353                 if (isdigit(end[1])) {
 354                         int match = match_multi_number(num, *end, date, end, tm);
 355                         if (match)
 356                                 return match;
 357                 }
 358         }
 359
 360         /*
 361          * None of the special formats? Try to guess what
 362          * the number meant. We use the number of digits
 363          * to make a more educated guess..
 364          */
 365         n = 0;
 366         do {
 367                 n++;
 368         } while (isdigit(date[n]));
 369
 370         /* Four-digit year or a timezone? */
 371         if (n == 4) {
 372                 if (num <= 1400 && *offset == -1) {
 373                         unsigned int minutes = num % 100;
 374                         unsigned int hours = num / 100;
 375                         *offset = hours*60 + minutes;
 376                 } else if (num > 1900 && num < 2100)
 377                         tm->tm_year = num - 1900;
 378                 return n;
 379         }
 380
 381         /*
 382          * NOTE! We will give precedence to day-of-month over month or
 383          * year numbers in the 1-12 range. So 05 is always "mday 5",
 384          * unless we already have a mday..
 385          *
 386          * IOW, 01 Apr 05 parses as "April 1st, 2005".
 387          */
 388         if (num > 0 && num < 32 && tm->tm_mday < 0) {
 389                 tm->tm_mday = num;
 390                 return n;
 391         }
 392
 393         /* Two-digit year? */
 394         if (n == 2 && tm->tm_year < 0) {
 395                 if (num < 10 && tm->tm_mday >= 0) {
 396                         tm->tm_year = num + 100;
 397                         return n;
 398                 }
 399                 if (num >= 70) {
 400                         tm->tm_year = num;
 401                         return n;
 402                 }
 403         }
 404
 405         if (num > 0 && num < 32) {
 406                 tm->tm_mday = num;
 407         } else if (num > 1900) {
 408                 tm->tm_year = num - 1900;
 409         } else if (num > 70) {
 410                 tm->tm_year = num;
 411         } else if (num > 0 && num < 13) {
 412                 tm->tm_mon = num-1;
 413         }
 414
 415         return n;
 416 }
 417
 418 static int match_tz(const char *date, int *offp)
 419 {
 420         char *end;
 421         int offset = strtoul(date+1, &end, 10);
 422         int min, hour;
 423         int n = end - date - 1;
 424
 425         min = offset % 100;
 426         hour = offset / 100;
 427
 428         /*
 429          * Don't accept any random crap.. At least 3 digits, and
 430          * a valid minute. We might want to check that the minutes
 431          * are divisible by 30 or something too.
 432          */
 433         if (min < 60 && n > 2) {
 434                 offset = hour*60+min;
 435                 if (*date == '-')
 436                         offset = -offset;
 437
 438                 *offp = offset;
 439         }
 440         return end - date;
 441 }
 442
 443 static int date_string(unsigned long date, int offset, char *buf, int len)
 444 {
 445         int sign = '+';
 446
 447         if (offset < 0) {
 448                 offset = -offset;
 449                 sign = '-';
 450         }
 451         return snprintf(buf, len, "%lu %c%02d%02d", date, sign, offset / 60, offset % 60);
 452 }
 453
 454 /* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
 455    (i.e. English) day/month names, and it doesn't work correctly with %z. */
 456 int parse_date(const char *date, char *result, int maxlen)
 457 {
 458         struct tm tm;
 459         int offset, tm_gmt;
 460         time_t then;
 461
 462         memset(&tm, 0, sizeof(tm));
 463         tm.tm_year = -1;
 464         tm.tm_mon = -1;
 465         tm.tm_mday = -1;
 466         tm.tm_isdst = -1;
 467         offset = -1;
 468         tm_gmt = 0;
 469
 470         for (;;) {
 471                 int match = 0;
 472                 unsigned char c = *date;
 473
 474                 /* Stop at end of string or newline */
 475                 if (!c || c == '\n')
 476                         break;
 477
 478                 if (isalpha(c))
 479                         match = match_alpha(date, &tm, &offset);
 480                 else if (isdigit(c))
 481                         match = match_digit(date, &tm, &offset, &tm_gmt);
 482                 else if ((c == '-' || c == '+') && isdigit(date[1]))
 483                         match = match_tz(date, &offset);
 484
 485                 if (!match) {
 486                         /* BAD CRAP */
 487                         match = 1;
 488                 }
 489
 490                 date += match;
 491         }
 492
 493         /* mktime uses local timezone */
 494         then = my_mktime(&tm);
 495         if (offset == -1)
 496                 offset = (then - mktime(&tm)) / 60;
 497
 498         if (then == -1)
 499                 return -1;
 500
 501         if (!tm_gmt)
 502                 then -= offset * 60;
 503         return date_string(then, offset, result, maxlen);
 504 }
 505
 506 void datestamp(char *buf, int bufsize)
 507 {
 508         time_t now;
 509         int offset;
 510
 511         time(&now);
 512
 513         offset = my_mktime(localtime(&now)) - now;
 514         offset /= 60;
 515
 516         date_string(now, offset, buf, bufsize);
 517 }
 518
 519 static void update_tm(struct tm *tm, unsigned long sec)
 520 {
 521         time_t n = mktime(tm) - sec;
 522         localtime_r(&n, tm);
 523 }
 524
 525 static void date_yesterday(struct tm *tm, int *num)
 526 {
 527         update_tm(tm, 24*60*60);
 528 }
 529
 530 static void date_time(struct tm *tm, int hour)
 531 {
 532         if (tm->tm_hour < hour)
 533                 date_yesterday(tm, NULL);
 534         tm->tm_hour = hour;
 535         tm->tm_min = 0;
 536         tm->tm_sec = 0;
 537 }
 538
 539 static void date_midnight(struct tm *tm, int *num)
 540 {
 541         date_time(tm, 0);
 542 }
 543
 544 static void date_noon(struct tm *tm, int *num)
 545 {
 546         date_time(tm, 12);
 547 }
 548
 549 static void date_tea(struct tm *tm, int *num)
 550 {
 551         date_time(tm, 17);
 552 }
 553
 554 static const struct special {
 555         const char *name;
 556         void (*fn)(struct tm *, int *);
 557 } special[] = {
 558         { "yesterday", date_yesterday },
 559         { "noon", date_noon },
 560         { "midnight", date_midnight },
 561         { "tea", date_tea },
 562         { NULL }
 563 };
 564
 565 static const char *number_name[] = {
 566         "zero", "one", "two", "three", "four",
 567         "five", "six", "seven", "eight", "nine", "ten",
 568 };
 569
 570 static const struct typelen {
 571         const char *type;
 572         int length;
 573 } typelen[] = {
 574         { "seconds", 1 },
 575         { "minutes", 60 },
 576         { "hours", 60*60 },
 577         { "days", 24*60*60 },
 578         { "weeks", 7*24*60*60 },
 579         { NULL }
 580 };
 581
 582 static const char *approxidate_alpha(const char *date, struct tm *tm, int *num)
 583 {
 584         const struct typelen *tl;
 585         const struct special *s;
 586         const char *end = date;
 587         int n = 1, i;
 588
 589         while (isalpha(*++end))
 590                 n++;
 591
 592         for (i = 0; i < 12; i++) {
 593                 int match = match_string(date, month_names[i]);
 594                 if (match >= 3) {
 595                         tm->tm_mon = i;
 596                         return end;
 597                 }
 598         }
 599
 600         for (s = special; s->name; s++) {
 601                 int len = strlen(s->name);
 602                 if (match_string(date, s->name) == len) {
 603                         s->fn(tm, num);
 604                         return end;
 605                 }
 606         }
 607
 608         if (!*num) {
 609                 for (i = 1; i < 11; i++) {
 610                         int len = strlen(number_name[i]);
 611                         if (match_string(date, number_name[i]) == len) {
 612                                 *num = i;
 613                                 return end;
 614                         }
 615                 }
 616                 if (match_string(date, "last") == 4)
 617                         *num = 1;
 618                 return end;
 619         }
 620
 621         tl = typelen;
 622         while (tl->type) {
 623                 int len = strlen(tl->type);
 624                 if (match_string(date, tl->type) >= len-1) {
 625                         update_tm(tm, tl->length * *num);
 626                         *num = 0;
 627                         return end;
 628                 }
 629                 tl++;
 630         }
 631
 632         for (i = 0; i < 7; i++) {
 633                 int match = match_string(date, weekday_names[i]);
 634                 if (match >= 3) {
 635                         int diff, n = *num -1;
 636                         *num = 0;
 637
 638                         diff = tm->tm_wday - i;
 639                         if (diff <= 0)
 640                                 n++;
 641                         diff += 7*n;
 642
 643                         update_tm(tm, diff * 24 * 60 * 60);
 644                         return end;
 645                 }
 646         }
 647
 648         if (match_string(date, "months") >= 5) {
 649                 int n = tm->tm_mon - *num;
 650                 *num = 0;
 651                 while (n < 0) {
 652                         n += 12;
 653                         tm->tm_year--;
 654                 }
 655                 tm->tm_mon = n;
 656                 return end;
 657         }
 658
 659         if (match_string(date, "years") >= 4) {
 660                 tm->tm_year -= *num;
 661                 *num = 0;
 662                 return end;
 663         }
 664
 665         return end;
 666 }
 667
 668 unsigned long approxidate(const char *date)
 669 {
 670         int number = 0;
 671         struct tm tm, now;
 672         struct timeval tv;
 673         char buffer[50];
 674
 675         if (parse_date(date, buffer, sizeof(buffer)) > 0)
 676                 return strtoul(buffer, NULL, 10);
 677
 678         gettimeofday(&tv, NULL);
 679         localtime_r(&tv.tv_sec, &tm);
 680         now = tm;
 681         for (;;) {
 682                 unsigned char c = *date;
 683                 if (!c)
 684                         break;
 685                 date++;
 686                 if (isdigit(c)) {
 687                         char *end;
 688                         number = strtoul(date-1, &end, 10);
 689                         date = end;
 690                         continue;
 691                 }
 692                 if (isalpha(c))
 693                         date = approxidate_alpha(date-1, &tm, &number);
 694         }
 695         if (number > 0 && number < 32)
 696                 tm.tm_mday = number;
 697         if (tm.tm_mon > now.tm_mon && tm.tm_year == now.tm_year)
 698                 tm.tm_year--;
 699         return mktime(&tm);
 700 }