release/src/router/glib/gdate.c

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Library General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19
  20 /*
  21  * Modified by the GLib Team and others 1997-1999.  See the AUTHORS
  22  * file for a list of people on the GLib Team.  See the ChangeLog
  23  * files for a list of changes.  These files are distributed with
  24  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  25  */
  26
  27 /*
  28  * MT safe
  29  */
  30
  31 #ifdef HAVE_CONFIG_H
  32 #include <config.h>
  33 #endif
  34
  35 #include "glib.h"
  36
  37 #include <time.h>
  38 #include <string.h>
  39 #include <ctype.h>
  40 #include <stdlib.h>
  41 #include <locale.h>
  42
  43 GDate*
  44 g_date_new ()
  45 {
  46   GDate *d = g_new0 (GDate, 1); /* happily, 0 is the invalid flag for everything. */
  47
  48   return d;
  49 }
  50
  51 GDate*
  52 g_date_new_dmy (GDateDay day, GDateMonth m, GDateYear y)
  53 {
  54   GDate *d;
  55   g_return_val_if_fail (g_date_valid_dmy (day, m, y), NULL);
  56
  57   d = g_new (GDate, 1);
  58
  59   d->julian = FALSE;
  60   d->dmy    = TRUE;
  61
  62   d->month = m;
  63   d->day   = day;
  64   d->year  = y;
  65
  66   g_assert (g_date_valid (d));
  67
  68   return d;
  69 }
  70
  71 GDate*
  72 g_date_new_julian (guint32 j)
  73 {
  74   GDate *d;
  75   g_return_val_if_fail (g_date_valid_julian (j), NULL);
  76
  77   d = g_new (GDate, 1);
  78
  79   d->julian = TRUE;
  80   d->dmy    = FALSE;
  81
  82   d->julian_days = j;
  83
  84   g_assert (g_date_valid (d));
  85
  86   return d;
  87 }
  88
  89 void
  90 g_date_free (GDate *d)
  91 {
  92   g_return_if_fail (d != NULL);
  93
  94   g_free (d);
  95 }
  96
  97 gboolean
  98 g_date_valid (GDate       *d)
  99 {
 100   g_return_val_if_fail (d != NULL, FALSE);
 101
 102   return (d->julian || d->dmy);
 103 }
 104
 105 static const guint8 days_in_months[2][13] =
 106 {  /* error, jan feb mar apr may jun jul aug sep oct nov dec */
 107   {  0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
 108   {  0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } /* leap year */
 109 };
 110
 111 static const guint16 days_in_year[2][14] =
 112 {  /* 0, jan feb mar apr may  jun  jul  aug  sep  oct  nov  dec */
 113   {  0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
 114   {  0, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
 115 };
 116
 117 gboolean
 118 g_date_valid_month (GDateMonth   m)
 119 {
 120   return ( (m > G_DATE_BAD_MONTH) && (m < 13) );
 121 }
 122
 123 gboolean
 124 g_date_valid_year (GDateYear    y)
 125 {
 126   return ( y > G_DATE_BAD_YEAR );
 127 }
 128
 129 gboolean
 130 g_date_valid_day (GDateDay     d)
 131 {
 132   return ( (d > G_DATE_BAD_DAY) && (d < 32) );
 133 }
 134
 135 gboolean
 136 g_date_valid_weekday (GDateWeekday w)
 137 {
 138   return ( (w > G_DATE_BAD_WEEKDAY) && (w < 8) );
 139 }
 140
 141 gboolean
 142 g_date_valid_julian (guint32      j)
 143 {
 144   return (j > G_DATE_BAD_JULIAN);
 145 }
 146
 147 gboolean
 148 g_date_valid_dmy (GDateDay     d,
 149                   GDateMonth   m,
 150                   GDateYear    y)
 151 {
 152   return ( (m > G_DATE_BAD_MONTH) &&
 153            (m < 13)               &&
 154            (d > G_DATE_BAD_DAY)   &&
 155            (y > G_DATE_BAD_YEAR)  &&   /* must check before using g_date_is_leap_year */
 156            (d <=  (g_date_is_leap_year (y) ?
 157                    days_in_months[1][m] : days_in_months[0][m])) );
 158 }
 159
 160
 161 /* "Julian days" just means an absolute number of days, where Day 1 ==
 162  *   Jan 1, Year 1
 163  */
 164 static void
 165 g_date_update_julian (GDate *d)
 166 {
 167   GDateYear year;
 168   gint index;
 169
 170   g_return_if_fail (d != NULL);
 171   g_return_if_fail (d->dmy);
 172   g_return_if_fail (!d->julian);
 173   g_return_if_fail (g_date_valid_dmy (d->day, d->month, d->year));
 174
 175   /* What we actually do is: multiply years * 365 days in the year,
 176    *  add the number of years divided by 4, subtract the number of
 177    *  years divided by 100 and add the number of years divided by 400,
 178    *  which accounts for leap year stuff. Code from Steffen Beyer's
 179    *  DateCalc.
 180    */
 181
 182   year = d->year - 1; /* we know d->year > 0 since it's valid */
 183
 184   d->julian_days = year * 365U;
 185   d->julian_days += (year >>= 2); /* divide by 4 and add */
 186   d->julian_days -= (year /= 25); /* divides original # years by 100 */
 187   d->julian_days += year >> 2;    /* divides by 4, which divides original by 400 */
 188
 189   index = g_date_is_leap_year (d->year) ? 1 : 0;
 190
 191   d->julian_days += days_in_year[index][d->month] + d->day;
 192
 193   g_return_if_fail (g_date_valid_julian (d->julian_days));
 194
 195   d->julian = TRUE;
 196 }
 197
 198 static void
 199 g_date_update_dmy (GDate *d)
 200 {
 201   GDateYear y;
 202   GDateMonth m;
 203   GDateDay day;
 204
 205   guint32 A, B, C, D, E, M;
 206
 207   g_return_if_fail (d != NULL);
 208   g_return_if_fail (d->julian);
 209   g_return_if_fail (!d->dmy);
 210   g_return_if_fail (g_date_valid_julian (d->julian_days));
 211
 212   /* Formula taken from the Calendar FAQ; the formula was for the
 213    *  Julian Period which starts on 1 January 4713 BC, so we add
 214    *  1,721,425 to the number of days before doing the formula.
 215    *
 216    * I'm sure this can be simplified for our 1 January 1 AD period
 217    * start, but I can't figure out how to unpack the formula.
 218    */
 219
 220   A = d->julian_days + 1721425 + 32045;
 221   B = ( 4 *(A + 36524) )/ 146097 - 1;
 222   C = A - (146097 * B)/4;
 223   D = ( 4 * (C + 365) ) / 1461 - 1;
 224   E = C - ((1461*D) / 4);
 225   M = (5 * (E - 1) + 2)/153;
 226
 227   m = M + 3 - (12*(M/10));
 228   day = E - (153*M + 2)/5;
 229   y = 100 * B + D - 4800 + (M/10);
 230
 231 #ifdef G_ENABLE_DEBUG
 232   if (!g_date_valid_dmy (day, m, y))
 233     {
 234       g_warning ("\nOOPS julian: %u  computed dmy: %u %u %u\n",
 235                  d->julian_days, day, m, y);
 236     }
 237 #endif
 238
 239   d->month = m;
 240   d->day   = day;
 241   d->year  = y;
 242
 243   d->dmy = TRUE;
 244 }
 245
 246 GDateWeekday
 247 g_date_weekday (GDate *d)
 248 {
 249   g_return_val_if_fail (d != NULL, G_DATE_BAD_WEEKDAY);
 250   g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_WEEKDAY);
 251
 252   if (!d->julian)
 253     {
 254       g_date_update_julian (d);
 255     }
 256   g_return_val_if_fail (d->julian, G_DATE_BAD_WEEKDAY);
 257
 258   return ((d->julian_days - 1) % 7) + 1;
 259 }
 260
 261 GDateMonth
 262 g_date_month (GDate *d)
 263 {
 264   g_return_val_if_fail (d != NULL, G_DATE_BAD_MONTH);
 265   g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_MONTH);
 266
 267   if (!d->dmy)
 268     {
 269       g_date_update_dmy (d);
 270     }
 271   g_return_val_if_fail (d->dmy, G_DATE_BAD_MONTH);
 272
 273   return d->month;
 274 }
 275
 276 GDateYear
 277 g_date_year (GDate *d)
 278 {
 279   g_return_val_if_fail (d != NULL, G_DATE_BAD_YEAR);
 280   g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_YEAR);
 281
 282   if (!d->dmy)
 283     {
 284       g_date_update_dmy (d);
 285     }
 286   g_return_val_if_fail (d->dmy, G_DATE_BAD_YEAR);
 287
 288   return d->year;
 289 }
 290
 291 GDateDay
 292 g_date_day (GDate *d)
 293 {
 294   g_return_val_if_fail (d != NULL, G_DATE_BAD_DAY);
 295   g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_DAY);
 296
 297   if (!d->dmy)
 298     {
 299       g_date_update_dmy (d);
 300     }
 301   g_return_val_if_fail (d->dmy, G_DATE_BAD_DAY);
 302
 303   return d->day;
 304 }
 305
 306 guint32
 307 g_date_julian (GDate *d)
 308 {
 309   g_return_val_if_fail (d != NULL, G_DATE_BAD_JULIAN);
 310   g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_JULIAN);
 311
 312   if (!d->julian)
 313     {
 314       g_date_update_julian (d);
 315     }
 316   g_return_val_if_fail (d->julian, G_DATE_BAD_JULIAN);
 317
 318   return d->julian_days;
 319 }
 320
 321 guint
 322 g_date_day_of_year (GDate *d)
 323 {
 324   gint index;
 325
 326   g_return_val_if_fail (d != NULL, 0);
 327   g_return_val_if_fail (g_date_valid (d), 0);
 328
 329   if (!d->dmy)
 330     {
 331       g_date_update_dmy (d);
 332     }
 333   g_return_val_if_fail (d->dmy, 0);
 334
 335   index = g_date_is_leap_year (d->year) ? 1 : 0;
 336
 337   return (days_in_year[index][d->month] + d->day);
 338 }
 339
 340 guint
 341 g_date_monday_week_of_year (GDate *d)
 342 {
 343   GDateWeekday wd;
 344   guint day;
 345   GDate first;
 346
 347   g_return_val_if_fail (d != NULL, 0);
 348   g_return_val_if_fail (g_date_valid (d), 0);
 349
 350   if (!d->dmy)
 351     {
 352       g_date_update_dmy (d);
 353     }
 354   g_return_val_if_fail (d->dmy, 0);
 355
 356   g_date_clear (&first, 1);
 357
 358   g_date_set_dmy (&first, 1, 1, d->year);
 359
 360   wd = g_date_weekday (&first) - 1; /* make Monday day 0 */
 361   day = g_date_day_of_year (d) - 1;
 362
 363   return ((day + wd)/7U + (wd == 0 ? 1 : 0));
 364 }
 365
 366 guint
 367 g_date_sunday_week_of_year (GDate *d)
 368 {
 369   GDateWeekday wd;
 370   guint day;
 371   GDate first;
 372
 373   g_return_val_if_fail (d != NULL, 0);
 374   g_return_val_if_fail (g_date_valid (d), 0);
 375
 376   if (!d->dmy)
 377     {
 378       g_date_update_dmy (d);
 379     }
 380   g_return_val_if_fail (d->dmy, 0);
 381
 382   g_date_clear (&first, 1);
 383
 384   g_date_set_dmy (&first, 1, 1, d->year);
 385
 386   wd = g_date_weekday (&first);
 387   if (wd == 7) wd = 0; /* make Sunday day 0 */
 388   day = g_date_day_of_year (d) - 1;
 389
 390   return ((day + wd)/7U + (wd == 0 ? 1 : 0));
 391 }
 392
 393 void
 394 g_date_clear (GDate       *d, guint ndates)
 395 {
 396   g_return_if_fail (d != NULL);
 397   g_return_if_fail (ndates != 0);
 398
 399   memset (d, 0x0, ndates*sizeof (GDate));
 400 }
 401
 402 G_LOCK_DEFINE_STATIC (g_date_global);
 403
 404 /* These are for the parser, output to the user should use *
 405  * g_date_strftime () - this creates more never-freed memory to annoy
 406  * all those memory debugger users. :-)
 407  */
 408
 409 static gchar *long_month_names[13] =
 410 {
 411   "Error", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 412 };
 413
 414 static gchar *short_month_names[13] =
 415 {
 416   "Error", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 417 };
 418
 419 /* This tells us if we need to update the parse info */
 420 static gchar *current_locale = NULL;
 421
 422 /* order of these in the current locale */
 423 static GDateDMY dmy_order[3] =
 424 {
 425    G_DATE_DAY, G_DATE_MONTH, G_DATE_YEAR
 426 };
 427
 428 /* Where to chop two-digit years: i.e., for the 1930 default, numbers
 429  * 29 and below are counted as in the year 2000, numbers 30 and above
 430  * are counted as in the year 1900.
 431  */
 432
 433 static GDateYear twodigit_start_year = 1930;
 434
 435 /* It is impossible to enter a year between 1 AD and 99 AD with this
 436  * in effect.
 437  */
 438 static gboolean using_twodigit_years = FALSE;
 439
 440 struct _GDateParseTokens {
 441   gint num_ints;
 442   gint n[3];
 443   guint month;
 444 };
 445
 446 typedef struct _GDateParseTokens GDateParseTokens;
 447
 448 #define NUM_LEN 10
 449
 450 /* HOLDS: g_date_global_lock */
 451 static void
 452 g_date_fill_parse_tokens (const gchar *str, GDateParseTokens *pt)
 453 {
 454   gchar num[4][NUM_LEN+1];
 455   gint i;
 456   const guchar *s;
 457
 458   /* We count 4, but store 3; so we can give an error
 459    * if there are 4.
 460    */
 461   num[0][0] = num[1][0] = num[2][0] = num[3][0] = '\0';
 462
 463   s = str;
 464   pt->num_ints = 0;
 465   while (*s && pt->num_ints < 4)
 466     {
 467
 468       i = 0;
 469       while (*s && isdigit (*s) && i <= NUM_LEN)
 470         {
 471           num[pt->num_ints][i] = *s;
 472           ++s;
 473           ++i;
 474         }
 475
 476       if (i > 0)
 477         {
 478           num[pt->num_ints][i] = '\0';
 479           ++(pt->num_ints);
 480         }
 481
 482       if (*s == '\0') break;
 483
 484       ++s;
 485     }
 486
 487   pt->n[0] = pt->num_ints > 0 ? atoi (num[0]) : 0;
 488   pt->n[1] = pt->num_ints > 1 ? atoi (num[1]) : 0;
 489   pt->n[2] = pt->num_ints > 2 ? atoi (num[2]) : 0;
 490
 491   pt->month = G_DATE_BAD_MONTH;
 492
 493   if (pt->num_ints < 3)
 494     {
 495       gchar lcstr[128];
 496       int i = 1;
 497
 498       strncpy (lcstr, str, 127);
 499       g_strdown (lcstr);
 500
 501       while (i < 13)
 502         {
 503           if (long_month_names[i] != NULL)
 504             {
 505               const gchar *found = strstr (lcstr, long_month_names[i]);
 506
 507               if (found != NULL)
 508                 {
 509                   pt->month = i;
 510                   return;
 511                 }
 512             }
 513
 514           if (short_month_names[i] != NULL)
 515             {
 516               const gchar *found = strstr (lcstr, short_month_names[i]);
 517
 518               if (found != NULL)
 519                 {
 520                   pt->month = i;
 521                   return;
 522                 }
 523             }
 524
 525           ++i;
 526         }
 527     }
 528 }
 529
 530 /* HOLDS: g_date_global_lock */
 531 static void
 532 g_date_prepare_to_parse (const gchar *str, GDateParseTokens *pt)
 533 {
 534   const gchar *locale = setlocale (LC_TIME, NULL);
 535   gboolean recompute_localeinfo = FALSE;
 536   GDate d;
 537
 538   g_return_if_fail (locale != NULL); /* should not happen */
 539
 540   g_date_clear (&d, 1);              /* clear for scratch use */
 541
 542   if ( (current_locale == NULL) || (strcmp (locale, current_locale) != 0) )
 543     {
 544       recompute_localeinfo = TRUE;  /* Uh, there used to be a reason for the temporary */
 545     }
 546
 547   if (recompute_localeinfo)
 548     {
 549       int i = 1;
 550       GDateParseTokens testpt;
 551       gchar buf[128];
 552
 553       g_free (current_locale); /* still works if current_locale == NULL */
 554
 555       current_locale = g_strdup (locale);
 556
 557       while (i < 13)
 558         {
 559           g_date_set_dmy (&d, 1, i, 1);
 560
 561           g_return_if_fail (g_date_valid (&d));
 562
 563           g_date_strftime (buf, 127, "%b", &d);
 564           g_free (short_month_names[i]);
 565           g_strdown (buf);
 566           short_month_names[i] = g_strdup (buf);
 567
 568
 569
 570           g_date_strftime (buf, 127, "%B", &d);
 571           g_free (long_month_names[i]);
 572           g_strdown (buf);
 573           long_month_names[i] = g_strdup (buf);
 574
 575           ++i;
 576         }
 577
 578       /* Determine DMY order */
 579
 580       /* had to pick a random day - don't change this, some strftimes
 581        * are broken on some days, and this one is good so far. */
 582       g_date_set_dmy (&d, 4, 7, 1976);
 583
 584       g_date_strftime (buf, 127, "%x", &d);
 585
 586       g_date_fill_parse_tokens (buf, &testpt);
 587
 588       i = 0;
 589       while (i < testpt.num_ints)
 590         {
 591           switch (testpt.n[i])
 592             {
 593             case 7:
 594               dmy_order[i] = G_DATE_MONTH;
 595               break;
 596             case 4:
 597               dmy_order[i] = G_DATE_DAY;
 598               break;
 599             case 76:
 600               using_twodigit_years = TRUE; /* FALL THRU */
 601             case 1976:
 602               dmy_order[i] = G_DATE_YEAR;
 603               break;
 604             default:
 605               /* leave it unchanged */
 606               break;
 607             }
 608           ++i;
 609         }
 610
 611 #ifdef G_ENABLE_DEBUG
 612       g_message ("**GDate prepared a new set of locale-specific parse rules.");
 613       i = 1;
 614       while (i < 13)
 615         {
 616           g_message ("  %s   %s", long_month_names[i], short_month_names[i]);
 617           ++i;
 618         }
 619       if (using_twodigit_years)
 620         {
 621           g_message ("**Using twodigit years with cutoff year: %u", twodigit_start_year);
 622         }
 623       {
 624         gchar *strings[3];
 625         i = 0;
 626         while (i < 3)
 627           {
 628             switch (dmy_order[i])
 629               {
 630               case G_DATE_MONTH:
 631                 strings[i] = "Month";
 632                 break;
 633               case G_DATE_YEAR:
 634                 strings[i] = "Year";
 635                 break;
 636               case G_DATE_DAY:
 637                 strings[i] = "Day";
 638                 break;
 639               default:
 640                 strings[i] = NULL;
 641                 break;
 642               }
 643             ++i;
 644           }
 645         g_message ("**Order: %s, %s, %s", strings[0], strings[1], strings[2]);
 646         g_message ("**Sample date in this locale: `%s'", buf);
 647       }
 648 #endif
 649     }
 650
 651   g_date_fill_parse_tokens (str, pt);
 652 }
 653
 654 void
 655 g_date_set_parse (GDate       *d,
 656                   const gchar *str)
 657 {
 658   GDateParseTokens pt;
 659   guint m = G_DATE_BAD_MONTH, day = G_DATE_BAD_DAY, y = G_DATE_BAD_YEAR;
 660
 661   g_return_if_fail (d != NULL);
 662
 663   /* set invalid */
 664   g_date_clear (d, 1);
 665
 666   G_LOCK (g_date_global);
 667
 668   g_date_prepare_to_parse (str, &pt);
 669
 670 #ifdef G_ENABLE_DEBUG
 671   g_message ("Found %d ints, `%d' `%d' `%d' and written out month %d",
 672              pt.num_ints, pt.n[0], pt.n[1], pt.n[2], pt.month);
 673 #endif
 674
 675
 676   if (pt.num_ints == 4)
 677     {
 678       G_UNLOCK (g_date_global);
 679       return; /* presumably a typo; bail out. */
 680     }
 681
 682   if (pt.num_ints > 1)
 683     {
 684       int i = 0;
 685       int j = 0;
 686
 687       g_assert (pt.num_ints < 4); /* i.e., it is 2 or 3 */
 688
 689       while (i < pt.num_ints && j < 3)
 690         {
 691           switch (dmy_order[j])
 692             {
 693             case G_DATE_MONTH:
 694             {
 695               if (pt.num_ints == 2 && pt.month != G_DATE_BAD_MONTH)
 696                 {
 697                   m = pt.month;
 698                   ++j;      /* skip months, but don't skip this number */
 699                   continue;
 700                 }
 701               else
 702                 m = pt.n[i];
 703             }
 704             break;
 705             case G_DATE_DAY:
 706             {
 707               if (pt.num_ints == 2 && pt.month == G_DATE_BAD_MONTH)
 708                 {
 709                   day = 1;
 710                   ++j;      /* skip days, since we may have month/year */
 711                   continue;
 712                 }
 713               day = pt.n[i];
 714             }
 715             break;
 716             case G_DATE_YEAR:
 717             {
 718               y  = pt.n[i];
 719
 720               if (using_twodigit_years && y < 100)
 721                 {
 722                   guint two     =  twodigit_start_year % 100;
 723                   guint century = (twodigit_start_year / 100) * 100;
 724
 725                   if (y < two)
 726                     century += 100;
 727
 728                   y += century;
 729                 }
 730             }
 731             break;
 732             default:
 733               break;
 734             }
 735
 736           ++i;
 737           ++j;
 738         }
 739
 740
 741       if (pt.num_ints == 3 && !g_date_valid_dmy (day, m, y))
 742         {
 743           /* Try YYYY MM DD */
 744           y   = pt.n[0];
 745           m   = pt.n[1];
 746           day = pt.n[2];
 747
 748           if (using_twodigit_years && y < 100)
 749             y = G_DATE_BAD_YEAR; /* avoids ambiguity */
 750         }
 751     }
 752   else if (pt.num_ints == 1)
 753     {
 754       if (pt.month != G_DATE_BAD_MONTH)
 755         {
 756           /* Month name and year? */
 757           m    = pt.month;
 758           day  = 1;
 759           y = pt.n[0];
 760         }
 761       else
 762         {
 763           /* Try yyyymmdd and yymmdd */
 764
 765           m   = (pt.n[0]/100) % 100;
 766           day = pt.n[0] % 100;
 767           y   = pt.n[0]/10000;
 768
 769           /* FIXME move this into a separate function */
 770           if (using_twodigit_years && y < 100)
 771             {
 772               guint two     =  twodigit_start_year % 100;
 773               guint century = (twodigit_start_year / 100) * 100;
 774
 775               if (y < two)
 776                 century += 100;
 777
 778               y += century;
 779             }
 780         }
 781     }
 782
 783   /* See if we got anything valid out of all this. */
 784   /* y < 8000 is to catch 19998 style typos; the library is OK up to 65535 or so */
 785   if (y < 8000 && g_date_valid_dmy (day, m, y))
 786     {
 787       d->month = m;
 788       d->day   = day;
 789       d->year  = y;
 790       d->dmy   = TRUE;
 791     }
 792 #ifdef G_ENABLE_DEBUG
 793   else
 794     g_message ("Rejected DMY %u %u %u", day, m, y);
 795 #endif
 796   G_UNLOCK (g_date_global);
 797 }
 798
 799 void
 800 g_date_set_time (GDate *d,
 801                  GTime  time)
 802 {
 803   time_t t = time;
 804   struct tm tm;
 805
 806   g_return_if_fail (d != NULL);
 807
 808 #ifdef HAVE_LOCALTIME_R
 809   localtime_r (&t, &tm);
 810 #else
 811   {
 812     struct tm *ptm = localtime (&t);
 813     g_assert (ptm);
 814     memcpy ((void *) &tm, (void *) ptm, sizeof(struct tm));
 815   }
 816 #endif
 817
 818   d->julian = FALSE;
 819
 820   d->month = tm.tm_mon + 1;
 821   d->day   = tm.tm_mday;
 822   d->year  = tm.tm_year + 1900;
 823
 824   g_return_if_fail (g_date_valid_dmy (d->day, d->month, d->year));
 825
 826   d->dmy    = TRUE;
 827 }
 828
 829 void
 830 g_date_set_month (GDate     *d,
 831                   GDateMonth m)
 832 {
 833   g_return_if_fail (d != NULL);
 834   g_return_if_fail (g_date_valid_month (m));
 835
 836   if (d->julian && !d->dmy) g_date_update_dmy(d);
 837   d->julian = FALSE;
 838
 839   d->month = m;
 840
 841   if (g_date_valid_dmy (d->day, d->month, d->year))
 842     d->dmy = TRUE;
 843   else
 844     d->dmy = FALSE;
 845 }
 846
 847 void
 848 g_date_set_day (GDate     *d,
 849                 GDateDay day)
 850 {
 851   g_return_if_fail (d != NULL);
 852   g_return_if_fail (g_date_valid_day (day));
 853
 854   if (d->julian && !d->dmy) g_date_update_dmy(d);
 855   d->julian = FALSE;
 856
 857   d->day = day;
 858
 859   if (g_date_valid_dmy (d->day, d->month, d->year))
 860     d->dmy = TRUE;
 861   else
 862     d->dmy = FALSE;
 863 }
 864
 865 void
 866 g_date_set_year (GDate     *d,
 867                  GDateYear  y)
 868 {
 869   g_return_if_fail (d != NULL);
 870   g_return_if_fail (g_date_valid_year (y));
 871
 872   if (d->julian && !d->dmy) g_date_update_dmy(d);
 873   d->julian = FALSE;
 874
 875   d->year = y;
 876
 877   if (g_date_valid_dmy (d->day, d->month, d->year))
 878     d->dmy = TRUE;
 879   else
 880     d->dmy = FALSE;
 881 }
 882
 883 void
 884 g_date_set_dmy (GDate     *d,
 885                 GDateDay   day,
 886                 GDateMonth m,
 887                 GDateYear  y)
 888 {
 889   g_return_if_fail (d != NULL);
 890   g_return_if_fail (g_date_valid_dmy (day, m, y));
 891
 892   d->julian = FALSE;
 893
 894   d->month = m;
 895   d->day   = day;
 896   d->year  = y;
 897
 898   d->dmy = TRUE;
 899 }
 900
 901 void
 902 g_date_set_julian (GDate *d, guint32 j)
 903 {
 904   g_return_if_fail (d != NULL);
 905   g_return_if_fail (g_date_valid_julian (j));
 906
 907   d->julian_days = j;
 908   d->julian = TRUE;
 909   d->dmy = FALSE;
 910 }
 911
 912
 913 gboolean
 914 g_date_is_first_of_month (GDate *d)
 915 {
 916   g_return_val_if_fail (d != NULL, FALSE);
 917   g_return_val_if_fail (g_date_valid (d), FALSE);
 918
 919   if (!d->dmy)
 920     {
 921       g_date_update_dmy (d);
 922     }
 923   g_return_val_if_fail (d->dmy, FALSE);
 924
 925   if (d->day == 1) return TRUE;
 926   else return FALSE;
 927 }
 928
 929 gboolean
 930 g_date_is_last_of_month (GDate *d)
 931 {
 932   gint index;
 933
 934   g_return_val_if_fail (d != NULL, FALSE);
 935   g_return_val_if_fail (g_date_valid (d), FALSE);
 936
 937   if (!d->dmy)
 938     {
 939       g_date_update_dmy (d);
 940     }
 941   g_return_val_if_fail (d->dmy, FALSE);
 942
 943   index = g_date_is_leap_year (d->year) ? 1 : 0;
 944
 945   if (d->day == days_in_months[index][d->month]) return TRUE;
 946   else return FALSE;
 947 }
 948
 949 void
 950 g_date_add_days (GDate *d, guint ndays)
 951 {
 952   g_return_if_fail (d != NULL);
 953   g_return_if_fail (g_date_valid (d));
 954
 955   if (!d->julian)
 956     {
 957       g_date_update_julian (d);
 958     }
 959   g_return_if_fail (d->julian);
 960
 961   d->julian_days += ndays;
 962   d->dmy = FALSE;
 963 }
 964
 965 void
 966 g_date_subtract_days (GDate *d, guint ndays)
 967 {
 968   g_return_if_fail (d != NULL);
 969   g_return_if_fail (g_date_valid (d));
 970
 971   if (!d->julian)
 972     {
 973       g_date_update_julian (d);
 974     }
 975   g_return_if_fail (d->julian);
 976   g_return_if_fail (d->julian_days > ndays);
 977
 978   d->julian_days -= ndays;
 979   d->dmy = FALSE;
 980 }
 981
 982 void
 983 g_date_add_months (GDate       *d,
 984                    guint        nmonths)
 985 {
 986   guint years, months;
 987   gint index;
 988
 989   g_return_if_fail (d != NULL);
 990   g_return_if_fail (g_date_valid (d));
 991
 992   if (!d->dmy)
 993     {
 994       g_date_update_dmy (d);
 995     }
 996   g_return_if_fail (d->dmy);
 997
 998   nmonths += d->month - 1;
 999
1000   years  = nmonths/12;
1001   months = nmonths%12;
1002
1003   d->month = months + 1;
1004   d->year  += years;
1005
1006   index = g_date_is_leap_year (d->year) ? 1 : 0;
1007
1008   if (d->day > days_in_months[index][d->month])
1009     d->day = days_in_months[index][d->month];
1010
1011   d->julian = FALSE;
1012
1013   g_return_if_fail (g_date_valid (d));
1014 }
1015
1016 void
1017 g_date_subtract_months (GDate       *d,
1018                         guint        nmonths)
1019 {
1020   guint years, months;
1021   gint index;
1022
1023   g_return_if_fail (d != NULL);
1024   g_return_if_fail (g_date_valid (d));
1025
1026   if (!d->dmy)
1027     {
1028       g_date_update_dmy (d);
1029     }
1030   g_return_if_fail (d->dmy);
1031
1032   years  = nmonths/12;
1033   months = nmonths%12;
1034
1035   g_return_if_fail (d->year > years);
1036
1037   d->year  -= years;
1038
1039   if (d->month > months) d->month -= months;
1040   else
1041     {
1042       months -= d->month;
1043       d->month = 12 - months;
1044       d->year -= 1;
1045     }
1046
1047   index = g_date_is_leap_year (d->year) ? 1 : 0;
1048
1049   if (d->day > days_in_months[index][d->month])
1050     d->day = days_in_months[index][d->month];
1051
1052   d->julian = FALSE;
1053
1054   g_return_if_fail (g_date_valid (d));
1055 }
1056
1057 void
1058 g_date_add_years (GDate       *d,
1059                   guint        nyears)
1060 {
1061   g_return_if_fail (d != NULL);
1062   g_return_if_fail (g_date_valid (d));
1063
1064   if (!d->dmy)
1065     {
1066       g_date_update_dmy (d);
1067     }
1068   g_return_if_fail (d->dmy);
1069
1070   d->year += nyears;
1071
1072   if (d->month == 2 && d->day == 29)
1073     {
1074       if (!g_date_is_leap_year (d->year))
1075         {
1076           d->day = 28;
1077         }
1078     }
1079
1080   d->julian = FALSE;
1081 }
1082
1083 void
1084 g_date_subtract_years (GDate       *d,
1085                        guint        nyears)
1086 {
1087   g_return_if_fail (d != NULL);
1088   g_return_if_fail (g_date_valid (d));
1089
1090   if (!d->dmy)
1091     {
1092       g_date_update_dmy (d);
1093     }
1094   g_return_if_fail (d->dmy);
1095   g_return_if_fail (d->year > nyears);
1096
1097   d->year -= nyears;
1098
1099   if (d->month == 2 && d->day == 29)
1100     {
1101       if (!g_date_is_leap_year (d->year))
1102         {
1103           d->day = 28;
1104         }
1105     }
1106
1107   d->julian = FALSE;
1108 }
1109
1110
1111 gboolean
1112 g_date_is_leap_year (GDateYear  year)
1113 {
1114   g_return_val_if_fail (g_date_valid_year (year), FALSE);
1115
1116   return ( (((year % 4) == 0) && ((year % 100) != 0)) ||
1117            (year % 400) == 0 );
1118 }
1119
1120 guint8
1121 g_date_days_in_month (GDateMonth month,
1122                       GDateYear  year)
1123 {
1124   gint index;
1125
1126   g_return_val_if_fail (g_date_valid_year (year), 0);
1127   g_return_val_if_fail (g_date_valid_month (month), 0);
1128
1129   index = g_date_is_leap_year (year) ? 1 : 0;
1130
1131   return days_in_months[index][month];
1132 }
1133
1134 guint8
1135 g_date_monday_weeks_in_year (GDateYear  year)
1136 {
1137   GDate d;
1138
1139   g_return_val_if_fail (g_date_valid_year (year), 0);
1140
1141   g_date_clear (&d, 1);
1142   g_date_set_dmy (&d, 1, 1, year);
1143   if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
1144   g_date_set_dmy (&d, 31, 12, year);
1145   if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
1146   if (g_date_is_leap_year (year))
1147     {
1148       g_date_set_dmy (&d, 2, 1, year);
1149       if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
1150       g_date_set_dmy (&d, 30, 12, year);
1151       if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
1152     }
1153   return 52;
1154 }
1155
1156 guint8
1157 g_date_sunday_weeks_in_year (GDateYear  year)
1158 {
1159   GDate d;
1160
1161   g_return_val_if_fail (g_date_valid_year (year), 0);
1162
1163   g_date_clear (&d, 1);
1164   g_date_set_dmy (&d, 1, 1, year);
1165   if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
1166   g_date_set_dmy (&d, 31, 12, year);
1167   if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
1168   if (g_date_is_leap_year (year))
1169     {
1170       g_date_set_dmy (&d, 2, 1, year);
1171       if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
1172       g_date_set_dmy (&d, 30, 12, year);
1173       if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
1174     }
1175   return 52;
1176 }
1177
1178 gint
1179 g_date_compare (GDate     *lhs,
1180                 GDate     *rhs)
1181 {
1182   g_return_val_if_fail (lhs != NULL, 0);
1183   g_return_val_if_fail (rhs != NULL, 0);
1184   g_return_val_if_fail (g_date_valid (lhs), 0);
1185   g_return_val_if_fail (g_date_valid (rhs), 0);
1186
1187   /* Remember the self-comparison case! I think it works right now. */
1188
1189   while (TRUE)
1190     {
1191
1192       if (lhs->julian && rhs->julian)
1193         {
1194           if (lhs->julian_days < rhs->julian_days) return -1;
1195           else if (lhs->julian_days > rhs->julian_days) return 1;
1196           else                                          return 0;
1197         }
1198       else if (lhs->dmy && rhs->dmy)
1199         {
1200           if (lhs->year < rhs->year)               return -1;
1201           else if (lhs->year > rhs->year)               return 1;
1202           else
1203             {
1204               if (lhs->month < rhs->month)         return -1;
1205               else if (lhs->month > rhs->month)         return 1;
1206               else
1207                 {
1208                   if (lhs->day < rhs->day)              return -1;
1209                   else if (lhs->day > rhs->day)              return 1;
1210                   else                                       return 0;
1211                 }
1212
1213             }
1214
1215         }
1216       else
1217         {
1218           if (!lhs->julian) g_date_update_julian (lhs);
1219           if (!rhs->julian) g_date_update_julian (rhs);
1220           g_return_val_if_fail (lhs->julian, 0);
1221           g_return_val_if_fail (rhs->julian, 0);
1222         }
1223
1224     }
1225   return 0; /* warnings */
1226 }
1227
1228
1229 void
1230 g_date_to_struct_tm (GDate      *d,
1231                      struct tm   *tm)
1232 {
1233   GDateWeekday day;
1234
1235   g_return_if_fail (d != NULL);
1236   g_return_if_fail (g_date_valid (d));
1237   g_return_if_fail (tm != NULL);
1238
1239   if (!d->dmy)
1240     {
1241       g_date_update_dmy (d);
1242     }
1243   g_return_if_fail (d->dmy);
1244
1245   /* zero all the irrelevant fields to be sure they're valid */
1246
1247   /* On Linux and maybe other systems, there are weird non-POSIX
1248    * fields on the end of struct tm that choke strftime if they
1249    * contain garbage.  So we need to 0 the entire struct, not just the
1250    * fields we know to exist.
1251    */
1252
1253   memset (tm, 0x0, sizeof (struct tm));
1254
1255   tm->tm_mday = d->day;
1256   tm->tm_mon  = d->month - 1; /* 0-11 goes in tm */
1257   tm->tm_year = ((int)d->year) - 1900; /* X/Open says tm_year can be negative */
1258
1259   day = g_date_weekday (d);
1260   if (day == 7) day = 0; /* struct tm wants days since Sunday, so Sunday is 0 */
1261
1262   tm->tm_wday = (int)day;
1263
1264   tm->tm_yday = g_date_day_of_year (d) - 1; /* 0 to 365 */
1265   tm->tm_isdst = -1; /* -1 means "information not available" */
1266 }
1267
1268 gsize
1269 g_date_strftime (gchar       *s,
1270                  gsize        slen,
1271                  const gchar *format,
1272                  GDate       *d)
1273 {
1274   struct tm tm;
1275   gsize retval;
1276
1277   g_return_val_if_fail (d != NULL, 0);
1278   g_return_val_if_fail (g_date_valid (d), 0);
1279   g_return_val_if_fail (slen > 0, 0);
1280   g_return_val_if_fail (format != 0, 0);
1281   g_return_val_if_fail (s != 0, 0);
1282
1283   g_date_to_struct_tm (d, &tm);
1284
1285   retval = strftime (s, slen, format, &tm);
1286   if (retval == 0)
1287     {
1288       /* If retval == 0, the contents of s are undefined.  We define
1289        *  them.
1290        */
1291       s[0] = '\0';
1292     }
1293   return retval;
1294 }