lib/libc/stdtime/strftime.c

   1 /*      $NetBSD: src/lib/libc/time/strftime.c,v 1.16 2004/05/12 23:03:11 kleink Exp $   */
   2 /*      $DragonFly: src/lib/libc/stdtime/strftime.c,v 1.5 2005/04/21 16:36:35 joerg Exp $ */
   3
   4 /*
   5 ** Based on the UCB version with the ID appearing below.
   6 ** This is ANSIish only when "multibyte character == plain character".
   7 */
   8
   9 /*
  10 ** We don't use these extensions in strftime operation even when
  11 ** supported by the local tzcode configuration.  A strictly
  12 ** conforming C application may leave them in undefined state.
  13 */
  14
  15 #ifdef _LIBC
  16 #undef TM_ZONE
  17 #undef TM_GMTOFF
  18 #endif
  19
  20 /*
  21 ** Copyright (c) 1989, 1993
  22 **      The Regents of the University of California.  All rights reserved.
  23 **
  24 ** Redistribution and use in source and binary forms, with or without
  25 ** modification, are permitted provided that the following conditions
  26 ** are met:
  27 ** 1. Redistributions of source code must retain the above copyright
  28 **    notice, this list of conditions and the following disclaimer.
  29 ** 2. Redistributions in binary form must reproduce the above copyright
  30 **    notice, this list of conditions and the following disclaimer in the
  31 **    documentation and/or other materials provided with the distribution.
  32 ** 3. All advertising materials mentioning features or use of this software
  33 **    must display the following acknowledgement:
  34 **      This product includes software developed by the University of
  35 **      California, Berkeley and its contributors.
  36 ** 4. Neither the name of the University nor the names of its contributors
  37 **    may be used to endorse or promote products derived from this software
  38 **    without specific prior written permission.
  39 **
  40 ** THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  41 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  43 ** ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  44 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  45 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  46 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  48 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  49 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  50 ** SUCH DAMAGE.
  51 */
  52
  53 #include <sys/localedef.h>
  54 #include <fcntl.h>
  55 #include <locale.h>
  56 #include <time.h>
  57
  58 #include "private.h"
  59 #include "tzfile.h"
  60
  61 #define Locale  _CurrentTimeLocale
  62
  63 static char *   _add(const char *, char *, const char *);
  64 static char *   _conv(int, const char *, char *, const char *);
  65 static char *   _fmt(const char *, const struct tm *, char *,
  66                      const char *, int *);
  67
  68 #define NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
  69
  70 #ifndef YEAR_2000_NAME
  71 #define YEAR_2000_NAME  "CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
  72 #endif /* !defined YEAR_2000_NAME */
  73
  74
  75 #define IN_NONE 0
  76 #define IN_SOME 1
  77 #define IN_THIS 2
  78 #define IN_ALL  3
  79
  80 size_t
  81 strftime(char * const s, const size_t maxsize, const char * const format,
  82          const struct tm * const t)
  83 {
  84         char *  p;
  85         int     warn;
  86
  87         tzset();
  88         warn = IN_NONE;
  89         p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn);
  90 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
  91         if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
  92                 (void) fprintf(stderr, "\n");
  93                 if (format == NULL)
  94                         (void) fprintf(stderr, "NULL strftime format ");
  95                 else    (void) fprintf(stderr, "strftime format \"%s\" ",
  96                                 format);
  97                 (void) fprintf(stderr, "yields only two digits of years in ");
  98                 if (warn == IN_SOME)
  99                         (void) fprintf(stderr, "some locales");
 100                 else if (warn == IN_THIS)
 101                         (void) fprintf(stderr, "the current locale");
 102                 else    (void) fprintf(stderr, "all locales");
 103                 (void) fprintf(stderr, "\n");
 104         }
 105 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
 106         if (p == s + maxsize)
 107                 return 0;
 108         *p = '\0';
 109         return p - s;
 110 }
 111
 112 static char *
 113 _fmt(const char *format, const struct tm * const t, char *pt,
 114      const char * const ptlim, int * warnp)
 115 {
 116         for ( ; *format; ++format) {
 117                 if (*format == '%') {
 118 label:
 119                         switch (*++format) {
 120                         case '\0':
 121                                 --format;
 122                                 break;
 123                         case 'A':
 124                                 pt = _add((t->tm_wday < 0 ||
 125                                         t->tm_wday >= DAYSPERWEEK) ?
 126                                         "?" : Locale->day[t->tm_wday],
 127                                         pt, ptlim);
 128                                 continue;
 129                         case 'a':
 130                                 pt = _add((t->tm_wday < 0 ||
 131                                         t->tm_wday >= DAYSPERWEEK) ?
 132                                         "?" : Locale->abday[t->tm_wday],
 133                                         pt, ptlim);
 134                                 continue;
 135                         case 'B':
 136                                 pt = _add((t->tm_mon < 0 ||
 137                                         t->tm_mon >= MONSPERYEAR) ?
 138                                         "?" : Locale->mon[t->tm_mon],
 139                                         pt, ptlim);
 140                                 continue;
 141                         case 'b':
 142                         case 'h':
 143                                 pt = _add((t->tm_mon < 0 ||
 144                                         t->tm_mon >= MONSPERYEAR) ?
 145                                         "?" : Locale->abmon[t->tm_mon],
 146                                         pt, ptlim);
 147                                 continue;
 148                         case 'C':
 149                                 /*
 150                                 ** %C used to do a...
 151                                 **      _fmt("%a %b %e %X %Y", t);
 152                                 ** ...whereas now POSIX 1003.2 calls for
 153                                 ** something completely different.
 154                                 ** (ado, 1993-05-24)
 155                                 */
 156                                 pt = _conv((t->tm_year + TM_YEAR_BASE) / 100,
 157                                         "%02d", pt, ptlim);
 158                                 continue;
 159                         case 'c':
 160                                 {
 161                                 int warn2 = IN_SOME;
 162
 163                                 pt = _fmt(Locale->d_t_fmt, t, pt, ptlim, warnp);
 164                                 if (warn2 == IN_ALL)
 165                                         warn2 = IN_THIS;
 166                                 if (warn2 > *warnp)
 167                                         *warnp = warn2;
 168                                 }
 169                                 continue;
 170                         case 'D':
 171                                 pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
 172                                 continue;
 173                         case 'd':
 174                                 pt = _conv(t->tm_mday, "%02d", pt, ptlim);
 175                                 continue;
 176                         case 'E':
 177                         case 'O':
 178                                 /*
 179                                 ** C99 locale modifiers.
 180                                 ** The sequences
 181                                 **      %Ec %EC %Ex %EX %Ey %EY
 182                                 **      %Od %oe %OH %OI %Om %OM
 183                                 **      %OS %Ou %OU %OV %Ow %OW %Oy
 184                                 ** are supposed to provide alternate
 185                                 ** representations.
 186                                 */
 187                                 goto label;
 188                         case 'e':
 189                                 pt = _conv(t->tm_mday, "%2d", pt, ptlim);
 190                                 continue;
 191                         case 'F':
 192                                 pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
 193                                 continue;
 194                         case 'H':
 195                                 pt = _conv(t->tm_hour, "%02d", pt, ptlim);
 196                                 continue;
 197                         case 'I':
 198                                 pt = _conv((t->tm_hour % 12) ?
 199                                         (t->tm_hour % 12) : 12,
 200                                         "%02d", pt, ptlim);
 201                                 continue;
 202                         case 'j':
 203                                 pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
 204                                 continue;
 205                         case 'k':
 206                                 /*
 207                                 ** This used to be...
 208                                 **      _conv(t->tm_hour % 12 ?
 209                                 **              t->tm_hour % 12 : 12, 2, ' ');
 210                                 ** ...and has been changed to the below to
 211                                 ** match SunOS 4.1.1 and Arnold Robbins'
 212                                 ** strftime version 3.0.  That is, "%k" and
 213                                 ** "%l" have been swapped.
 214                                 ** (ado, 1993-05-24)
 215                                 */
 216                                 pt = _conv(t->tm_hour, "%2d", pt, ptlim);
 217                                 continue;
 218 #ifdef KITCHEN_SINK
 219                         case 'K':
 220                                 /*
 221                                 ** After all this time, still unclaimed!
 222                                 */
 223                                 pt = _add("kitchen sink", pt, ptlim);
 224                                 continue;
 225 #endif /* defined KITCHEN_SINK */
 226                         case 'l':
 227                                 /*
 228                                 ** This used to be...
 229                                 **      _conv(t->tm_hour, 2, ' ');
 230                                 ** ...and has been changed to the below to
 231                                 ** match SunOS 4.1.1 and Arnold Robbin's
 232                                 ** strftime version 3.0.  That is, "%k" and
 233                                 ** "%l" have been swapped.
 234                                 ** (ado, 1993-05-24)
 235                                 */
 236                                 pt = _conv((t->tm_hour % 12) ?
 237                                         (t->tm_hour % 12) : 12,
 238                                         "%2d", pt, ptlim);
 239                                 continue;
 240                         case 'M':
 241                                 pt = _conv(t->tm_min, "%02d", pt, ptlim);
 242                                 continue;
 243                         case 'm':
 244                                 pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
 245                                 continue;
 246                         case 'n':
 247                                 pt = _add("\n", pt, ptlim);
 248                                 continue;
 249                         case 'p':
 250                                 pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
 251                                         Locale->am_pm[1] :
 252                                         Locale->am_pm[0],
 253                                         pt, ptlim);
 254                                 continue;
 255                         case 'R':
 256                                 pt = _fmt("%H:%M", t, pt, ptlim, warnp);
 257                                 continue;
 258                         case 'r':
 259                                 pt = _fmt("%I:%M:%S %p", t, pt, ptlim, warnp);
 260                                 continue;
 261                         case 'S':
 262                                 pt = _conv(t->tm_sec, "%02d", pt, ptlim);
 263                                 continue;
 264                         case 's':
 265                                 {
 266                                         struct tm       tm;
 267                                         char            buf[INT_STRLEN_MAXIMUM(
 268                                                                 time_t) + 1];
 269                                         time_t          mkt;
 270
 271                                         tm = *t;
 272                                         mkt = mktime(&tm);
 273                                         /* CONSTCOND */
 274                                         if (TYPE_SIGNED(time_t))
 275                                                 (void) sprintf(buf, "%ld",
 276                                                         (long) mkt);
 277                                         else    (void) sprintf(buf, "%lu",
 278                                                         (unsigned long) mkt);
 279                                         pt = _add(buf, pt, ptlim);
 280                                 }
 281                                 continue;
 282                         case 'T':
 283                                 pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
 284                                 continue;
 285                         case 't':
 286                                 pt = _add("\t", pt, ptlim);
 287                                 continue;
 288                         case 'U':
 289                                 pt = _conv((t->tm_yday + DAYSPERWEEK -
 290                                         t->tm_wday) / DAYSPERWEEK,
 291                                         "%02d", pt, ptlim);
 292                                 continue;
 293                         case 'u':
 294                                 /*
 295                                 ** From Arnold Robbins' strftime version 3.0:
 296                                 ** "ISO 8601: Weekday as a decimal number
 297                                 ** [1 (Monday) - 7]"
 298                                 ** (ado, 1993-05-24)
 299                                 */
 300                                 pt = _conv((t->tm_wday == 0) ?
 301                                         DAYSPERWEEK : t->tm_wday,
 302                                         "%d", pt, ptlim);
 303                                 continue;
 304                         case 'V':       /* ISO 8601 week number */
 305                         case 'G':       /* ISO 8601 year (four digits) */
 306                         case 'g':       /* ISO 8601 year (two digits) */
 307 /*
 308 ** From Arnold Robbins' strftime version 3.0:  "the week number of the
 309 ** year (the first Monday as the first day of week 1) as a decimal number
 310 ** (01-53)."
 311 ** (ado, 1993-05-24)
 312 **
 313 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
 314 ** "Week 01 of a year is per definition the first week which has the
 315 ** Thursday in this year, which is equivalent to the week which contains
 316 ** the fourth day of January. In other words, the first week of a new year
 317 ** is the week which has the majority of its days in the new year. Week 01
 318 ** might also contain days from the previous year and the week before week
 319 ** 01 of a year is the last week (52 or 53) of the previous year even if
 320 ** it contains days from the new year. A week starts with Monday (day 1)
 321 ** and ends with Sunday (day 7).  For example, the first week of the year
 322 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
 323 ** (ado, 1996-01-02)
 324 */
 325                                 {
 326                                         int     year;
 327                                         int     yday;
 328                                         int     wday;
 329                                         int     w;
 330
 331                                         year = t->tm_year + TM_YEAR_BASE;
 332                                         yday = t->tm_yday;
 333                                         wday = t->tm_wday;
 334                                         for ( ; ; ) {
 335                                                 int     len;
 336                                                 int     bot;
 337                                                 int     top;
 338
 339                                                 len = isleap(year) ?
 340                                                         DAYSPERLYEAR :
 341                                                         DAYSPERNYEAR;
 342                                                 /*
 343                                                 ** What yday (-3 ... 3) does
 344                                                 ** the ISO year begin on?
 345                                                 */
 346                                                 bot = ((yday + 11 - wday) %
 347                                                         DAYSPERWEEK) - 3;
 348                                                 /*
 349                                                 ** What yday does the NEXT
 350                                                 ** ISO year begin on?
 351                                                 */
 352                                                 top = bot -
 353                                                         (len % DAYSPERWEEK);
 354                                                 if (top < -3)
 355                                                         top += DAYSPERWEEK;
 356                                                 top += len;
 357                                                 if (yday >= top) {
 358                                                         ++year;
 359                                                         w = 1;
 360                                                         break;
 361                                                 }
 362                                                 if (yday >= bot) {
 363                                                         w = 1 + ((yday - bot) /
 364                                                                 DAYSPERWEEK);
 365                                                         break;
 366                                                 }
 367                                                 --year;
 368                                                 yday += isleap(year) ?
 369                                                         DAYSPERLYEAR :
 370                                                         DAYSPERNYEAR;
 371                                         }
 372 #ifdef XPG4_1994_04_09
 373                                         if ((w == 52
 374                                              && t->tm_mon == TM_JANUARY)
 375                                             || (w == 1
 376                                                 && t->tm_mon == TM_DECEMBER))
 377                                                 w = 53;
 378 #endif /* defined XPG4_1994_04_09 */
 379                                         if (*format == 'V')
 380                                                 pt = _conv(w, "%02d",
 381                                                         pt, ptlim);
 382                                         else if (*format == 'g') {
 383                                                 *warnp = IN_ALL;
 384                                                 pt = _conv(year % 100, "%02d",
 385                                                         pt, ptlim);
 386                                         } else  pt = _conv(year, "%04d",
 387                                                         pt, ptlim);
 388                                 }
 389                                 continue;
 390                         case 'v':
 391                                 /*
 392                                 ** From Arnold Robbins' strftime version 3.0:
 393                                 ** "date as dd-bbb-YYYY"
 394                                 ** (ado, 1993-05-24)
 395                                 */
 396                                 pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
 397                                 continue;
 398                         case 'W':
 399                                 pt = _conv((t->tm_yday + DAYSPERWEEK -
 400                                         (t->tm_wday ?
 401                                         (t->tm_wday - 1) :
 402                                         (DAYSPERWEEK - 1))) / DAYSPERWEEK,
 403                                         "%02d", pt, ptlim);
 404                                 continue;
 405                         case 'w':
 406                                 pt = _conv(t->tm_wday, "%d", pt, ptlim);
 407                                 continue;
 408                         case 'X':
 409                                 pt = _fmt(Locale->t_fmt, t, pt, ptlim, warnp);
 410                                 continue;
 411                         case 'x':
 412                                 {
 413                                 int     warn2 = IN_SOME;
 414
 415                                 pt = _fmt(Locale->d_fmt, t, pt, ptlim, &warn2);
 416                                 if (warn2 == IN_ALL)
 417                                         warn2 = IN_THIS;
 418                                 if (warn2 > *warnp)
 419                                         *warnp = warn2;
 420                                 }
 421                                 continue;
 422                         case 'y':
 423                                 *warnp = IN_ALL;
 424                                 pt = _conv((t->tm_year + TM_YEAR_BASE) % 100,
 425                                         "%02d", pt, ptlim);
 426                                 continue;
 427                         case 'Y':
 428                                 pt = _conv(t->tm_year + TM_YEAR_BASE, "%04d",
 429                                         pt, ptlim);
 430                                 continue;
 431                         case 'Z':
 432 #ifdef TM_ZONE
 433                                 if (t->TM_ZONE != NULL)
 434                                         pt = _add(t->TM_ZONE, pt, ptlim);
 435                                 else
 436 #endif /* defined TM_ZONE */
 437                                 if (t->tm_isdst >= 0)
 438                                         pt = _add(tzname[t->tm_isdst != 0],
 439                                                 pt, ptlim);
 440                                 /*
 441                                 ** C99 says that %Z must be replaced by the
 442                                 ** empty string if the time zone is not
 443                                 ** determinable.
 444                                 */
 445                                 continue;
 446                         case 'z':
 447                                 {
 448                                 int             diff;
 449                                 char const *    sign;
 450
 451                                 if (t->tm_isdst < 0)
 452                                         continue;
 453 #ifdef TM_GMTOFF
 454                                 diff = (int)t->TM_GMTOFF;
 455 #else /* !defined TM_GMTOFF */
 456                                 /*
 457                                 ** C99 says that the UTC offset must
 458                                 ** be computed by looking only at
 459                                 ** tm_isdst.  This requirement is
 460                                 ** incorrect, since it means the code
 461                                 ** must rely on magic (in this case
 462                                 ** altzone and timezone), and the
 463                                 ** magic might not have the correct
 464                                 ** offset.  Doing things correctly is
 465                                 ** tricky and requires disobeying C99;
 466                                 ** see GNU C strftime for details.
 467                                 ** For now, punt and conform to the
 468                                 ** standard, even though it's incorrect.
 469                                 **
 470                                 ** C99 says that %z must be replaced by the
 471                                 ** empty string if the time zone is not
 472                                 ** determinable, so output nothing if the
 473                                 ** appropriate variables are not available.
 474                                 */
 475 #ifndef STD_INSPIRED
 476                                 if (t->tm_isdst == 0)
 477 #ifdef USG_COMPAT
 478                                         diff = -timezone;
 479 #else /* !defined USG_COMPAT */
 480                                         continue;
 481 #endif /* !defined USG_COMPAT */
 482                                 else
 483 #ifdef ALTZONE
 484                                         diff = -altzone;
 485 #else /* !defined ALTZONE */
 486                                         continue;
 487 #endif /* !defined ALTZONE */
 488 #else /* defined STD_INSPIRED */
 489                                 {
 490                                         struct tm tmp;
 491                                         time_t lct, gct;
 492
 493                                         /*
 494                                         ** Get calendar time from t
 495                                         ** being treated as local.
 496                                         */
 497                                         tmp = *t; /* mktime discards const */
 498                                         lct = mktime(&tmp);
 499
 500                                         if (lct == (time_t)-1)
 501                                                 continue;
 502
 503                                         /*
 504                                         ** Get calendar time from t
 505                                         ** being treated as GMT.
 506                                         **/
 507                                         tmp = *t; /* mktime discards const */
 508                                         gct = timegm(&tmp);
 509
 510                                         if (gct == (time_t)-1)
 511                                                 continue;
 512
 513                                         /* LINTED difference will fit int */
 514                                         diff = (intmax_t)gct - (intmax_t)lct;
 515                                 }
 516 #endif /* defined STD_INSPIRED */
 517 #endif /* !defined TM_GMTOFF */
 518                                 if (diff < 0) {
 519                                         sign = "-";
 520                                         diff = -diff;
 521                                 } else  sign = "+";
 522                                 pt = _add(sign, pt, ptlim);
 523                                 diff /= 60;
 524                                 pt = _conv((diff/60)*100 + diff%60,
 525                                         "%04d", pt, ptlim);
 526                                 }
 527                                 continue;
 528                         case '+':
 529                                 pt = _fmt(Locale->d_t_fmt, t, pt, ptlim,
 530                                         warnp);
 531                                 continue;
 532                         case '%':
 533                         /*
 534                         ** X311J/88-090 (4.12.3.5): if conversion char is
 535                         ** undefined, behavior is undefined.  Print out the
 536                         ** character itself as printf(3) also does.
 537                         */
 538                         default:
 539                                 break;
 540                         }
 541                 }
 542                 if (pt == ptlim)
 543                         break;
 544                 *pt++ = *format;
 545         }
 546         return pt;
 547 }
 548
 549 static char *
 550 _conv(const int n, const char * const format, char * const pt,
 551       const char * const ptlim)
 552 {
 553         char    buf[INT_STRLEN_MAXIMUM(int) + 1];
 554
 555         (void) sprintf(buf, format, n);
 556         return _add(buf, pt, ptlim);
 557 }
 558
 559 static char *
 560 _add(const char *str, char *pt, const char * const ptlim)
 561 {
 562         while (pt < ptlim && (*pt = *str++) != '\0')
 563                 ++pt;
 564         return pt;
 565 }