lib/libc/stdtime/strftime.c

   1 /*
   2  * @(#)strftime.c       8.3
   3  * $NetBSD: strftime.c,v 1.19 2009/01/11 02:46:30 christos Exp $
   4  * $DragonFly: src/lib/libc/stdtime/strftime.c,v 1.7 2008/10/19 20:15:58 swildner Exp $
   5  */
   6
   7 /*
   8 ** Based on the UCB version with the ID appearing below.
   9 ** This is ANSIish only when "multibyte character == plain character".
  10 */
  11
  12 /*
  13 ** We don't use these extensions in strftime operation even when
  14 ** supported by the local tzcode configuration.  A strictly
  15 ** conforming C application may leave them in undefined state.
  16 */
  17
  18 #ifdef _LIBC
  19 #undef TM_ZONE
  20 #undef TM_GMTOFF
  21 #endif
  22
  23 /*
  24 ** Copyright (c) 1989, 1993
  25 **      The Regents of the University of California.  All rights reserved.
  26 **
  27 ** Redistribution and use in source and binary forms, with or without
  28 ** modification, are permitted provided that the following conditions
  29 ** are met:
  30 ** 1. Redistributions of source code must retain the above copyright
  31 **    notice, this list of conditions and the following disclaimer.
  32 ** 2. Redistributions in binary form must reproduce the above copyright
  33 **    notice, this list of conditions and the following disclaimer in the
  34 **    documentation and/or other materials provided with the distribution.
  35 ** 3. All advertising materials mentioning features or use of this software
  36 **    must display the following acknowledgement:
  37 **      This product includes software developed by the University of
  38 **      California, Berkeley and its contributors.
  39 ** 4. Neither the name of the University nor the names of its contributors
  40 **    may be used to endorse or promote products derived from this software
  41 **    without specific prior written permission.
  42 **
  43 ** THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  44 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  45 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  46 ** ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  47 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  48 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  49 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  50 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  51 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  52 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  53 ** SUCH DAMAGE.
  54 */
  55
  56 #include <sys/localedef.h>
  57 #include <fcntl.h>
  58 #include <locale.h>
  59 #include <time.h>
  60
  61 #include "private.h"
  62 #include "tzfile.h"
  63
  64 #define Locale  _CurrentTimeLocale
  65
  66 static char *   _add(const char *, char *, const char *);
  67 static char *   _conv(int, const char *, char *, const char *);
  68 static char *   _fmt(const char *, const struct tm *, char *,
  69                      const char *, int *);
  70 static char *   _yconv(int, int, int, int, char *, const char *);
  71
  72 #define NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
  73
  74 #ifndef YEAR_2000_NAME
  75 #define YEAR_2000_NAME  "CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
  76 #endif /* !defined YEAR_2000_NAME */
  77
  78 #define IN_NONE 0
  79 #define IN_SOME 1
  80 #define IN_THIS 2
  81 #define IN_ALL  3
  82
  83 size_t
  84 strftime(char * __restrict s, size_t maxsize, const char * __restrict format,
  85          const struct tm * __restrict t)
  86 {
  87         char *  p;
  88         int     warn;
  89
  90         tzset();
  91         warn = IN_NONE;
  92         p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn);
  93 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
  94         if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
  95                 fprintf(stderr, "\n");
  96                 if (format == NULL)
  97                         fprintf(stderr, "NULL strftime format ");
  98                 else    fprintf(stderr, "strftime format \"%s\" ",
  99                                 format);
 100                 fprintf(stderr, "yields only two digits of years in ");
 101                 if (warn == IN_SOME)
 102                         fprintf(stderr, "some locales");
 103                 else if (warn == IN_THIS)
 104                         fprintf(stderr, "the current locale");
 105                 else    fprintf(stderr, "all locales");
 106                 fprintf(stderr, "\n");
 107         }
 108 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
 109         if (p == s + maxsize)
 110                 return 0;
 111         *p = '\0';
 112         return p - s;
 113 }
 114
 115 static char *
 116 _fmt(const char *format, const struct tm * const t, char *pt,
 117      const char * const ptlim, int * warnp)
 118 {
 119         for ( ; *format; ++format) {
 120                 if (*format == '%') {
 121 label:
 122                         switch (*++format) {
 123                         case '\0':
 124                                 --format;
 125                                 break;
 126                         case 'A':
 127                                 pt = _add((t->tm_wday < 0 ||
 128                                         t->tm_wday >= DAYSPERWEEK) ?
 129                                         "?" : Locale->day[t->tm_wday],
 130                                         pt, ptlim);
 131                                 continue;
 132                         case 'a':
 133                                 pt = _add((t->tm_wday < 0 ||
 134                                         t->tm_wday >= DAYSPERWEEK) ?
 135                                         "?" : Locale->abday[t->tm_wday],
 136                                         pt, ptlim);
 137                                 continue;
 138                         case 'B':
 139                                 pt = _add((t->tm_mon < 0 ||
 140                                         t->tm_mon >= MONSPERYEAR) ?
 141                                         "?" : Locale->mon[t->tm_mon],
 142                                         pt, ptlim);
 143                                 continue;
 144                         case 'b':
 145                         case 'h':
 146                                 pt = _add((t->tm_mon < 0 ||
 147                                         t->tm_mon >= MONSPERYEAR) ?
 148                                         "?" : Locale->abmon[t->tm_mon],
 149                                         pt, ptlim);
 150                                 continue;
 151                         case 'C':
 152                                 /*
 153                                 ** %C used to do a...
 154                                 **      _fmt("%a %b %e %X %Y", t);
 155                                 ** ...whereas now POSIX 1003.2 calls for
 156                                 ** something completely different.
 157                                 ** (ado, 1993-05-24)
 158                                 */
 159                                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 0,
 160                                         pt, ptlim);
 161                                 continue;
 162                         case 'c':
 163                                 {
 164                                 int warn2 = IN_SOME;
 165
 166                                 pt = _fmt(Locale->d_t_fmt, t, pt, ptlim, &warn2);
 167                                 if (warn2 == IN_ALL)
 168                                         warn2 = IN_THIS;
 169                                 if (warn2 > *warnp)
 170                                         *warnp = warn2;
 171                                 }
 172                                 continue;
 173                         case 'D':
 174                                 pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
 175                                 continue;
 176                         case 'd':
 177                                 pt = _conv(t->tm_mday, "%02d", pt, ptlim);
 178                                 continue;
 179                         case 'E':
 180                         case 'O':
 181                                 /*
 182                                 ** C99 locale modifiers.
 183                                 ** The sequences
 184                                 **      %Ec %EC %Ex %EX %Ey %EY
 185                                 **      %Od %oe %OH %OI %Om %OM
 186                                 **      %OS %Ou %OU %OV %Ow %OW %Oy
 187                                 ** are supposed to provide alternate
 188                                 ** representations.
 189                                 */
 190                                 goto label;
 191                         case 'e':
 192                                 pt = _conv(t->tm_mday, "%2d", pt, ptlim);
 193                                 continue;
 194                         case 'F':
 195                                 pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
 196                                 continue;
 197                         case 'H':
 198                                 pt = _conv(t->tm_hour, "%02d", pt, ptlim);
 199                                 continue;
 200                         case 'I':
 201                                 pt = _conv((t->tm_hour % 12) ?
 202                                         (t->tm_hour % 12) : 12,
 203                                         "%02d", pt, ptlim);
 204                                 continue;
 205                         case 'j':
 206                                 pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
 207                                 continue;
 208                         case 'k':
 209                                 /*
 210                                 ** This used to be...
 211                                 **      _conv(t->tm_hour % 12 ?
 212                                 **              t->tm_hour % 12 : 12, 2, ' ');
 213                                 ** ...and has been changed to the below to
 214                                 ** match SunOS 4.1.1 and Arnold Robbins'
 215                                 ** strftime version 3.0. That is, "%k" and
 216                                 ** "%l" have been swapped.
 217                                 ** (ado, 1993-05-24)
 218                                 */
 219                                 pt = _conv(t->tm_hour, "%2d", pt, ptlim);
 220                                 continue;
 221 #ifdef KITCHEN_SINK
 222                         case 'K':
 223                                 /*
 224                                 ** After all this time, still unclaimed!
 225                                 */
 226                                 pt = _add("kitchen sink", pt, ptlim);
 227                                 continue;
 228 #endif /* defined KITCHEN_SINK */
 229                         case 'l':
 230                                 /*
 231                                 ** This used to be...
 232                                 **      _conv(t->tm_hour, 2, ' ');
 233                                 ** ...and has been changed to the below to
 234                                 ** match SunOS 4.1.1 and Arnold Robbin's
 235                                 ** strftime version 3.0. That is, "%k" and
 236                                 ** "%l" have been swapped.
 237                                 ** (ado, 1993-05-24)
 238                                 */
 239                                 pt = _conv((t->tm_hour % 12) ?
 240                                         (t->tm_hour % 12) : 12,
 241                                         "%2d", pt, ptlim);
 242                                 continue;
 243                         case 'M':
 244                                 pt = _conv(t->tm_min, "%02d", pt, ptlim);
 245                                 continue;
 246                         case 'm':
 247                                 pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
 248                                 continue;
 249                         case 'n':
 250                                 pt = _add("\n", pt, ptlim);
 251                                 continue;
 252                         case 'p':
 253                                 pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
 254                                         Locale->am_pm[1] :
 255                                         Locale->am_pm[0],
 256                                         pt, ptlim);
 257                                 continue;
 258                         case 'R':
 259                                 pt = _fmt("%H:%M", t, pt, ptlim, warnp);
 260                                 continue;
 261                         case 'r':
 262                                 pt = _fmt(Locale->t_fmt_ampm, t, pt, ptlim,
 263                                         warnp);
 264                                 continue;
 265                         case 'S':
 266                                 pt = _conv(t->tm_sec, "%02d", pt, ptlim);
 267                                 continue;
 268                         case 's':
 269                                 {
 270                                         struct tm       tm;
 271                                         char            buf[INT_STRLEN_MAXIMUM(
 272                                                                 time_t) + 1];
 273                                         time_t          mkt;
 274
 275                                         tm = *t;
 276                                         mkt = mktime(&tm);
 277                                         /* CONSTCOND */
 278                                         if (TYPE_SIGNED(time_t))
 279                                                 snprintf(buf, sizeof(buf),
 280                                                     "%ld", (long) mkt);
 281                                         else    snprintf(buf, sizeof(buf),
 282                                                     "%lu", (unsigned long)
 283                                                     mkt);
 284                                         pt = _add(buf, pt, ptlim);
 285                                 }
 286                                 continue;
 287                         case 'T':
 288                                 pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
 289                                 continue;
 290                         case 't':
 291                                 pt = _add("\t", pt, ptlim);
 292                                 continue;
 293                         case 'U':
 294                                 pt = _conv((t->tm_yday + DAYSPERWEEK -
 295                                         t->tm_wday) / DAYSPERWEEK,
 296                                         "%02d", pt, ptlim);
 297                                 continue;
 298                         case 'u':
 299                                 /*
 300                                 ** From Arnold Robbins' strftime version 3.0:
 301                                 ** "ISO 8601: Weekday as a decimal number
 302                                 ** [1 (Monday) - 7]"
 303                                 ** (ado, 1993-05-24)
 304                                 */
 305                                 pt = _conv((t->tm_wday == 0) ?
 306                                         DAYSPERWEEK : t->tm_wday,
 307                                         "%d", pt, ptlim);
 308                                 continue;
 309                         case 'V':       /* ISO 8601 week number */
 310                         case 'G':       /* ISO 8601 year (four digits) */
 311                         case 'g':       /* ISO 8601 year (two digits) */
 312 /*
 313 ** From Arnold Robbins' strftime version 3.0: "the week number of the
 314 ** year (the first Monday as the first day of week 1) as a decimal number
 315 ** (01-53)."
 316 ** (ado, 1993-05-24)
 317 **
 318 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
 319 ** "Week 01 of a year is per definition the first week which has the
 320 ** Thursday in this year, which is equivalent to the week which contains
 321 ** the fourth day of January. In other words, the first week of a new year
 322 ** is the week which has the majority of its days in the new year. Week 01
 323 ** might also contain days from the previous year and the week before week
 324 ** 01 of a year is the last week (52 or 53) of the previous year even if
 325 ** it contains days from the new year. A week starts with Monday (day 1)
 326 ** and ends with Sunday (day 7). For example, the first week of the year
 327 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
 328 ** (ado, 1996-01-02)
 329 */
 330                                 {
 331                                         int     year;
 332                                         int     base;
 333                                         int     yday;
 334                                         int     wday;
 335                                         int     w;
 336
 337                                         year = t->tm_year;
 338                                         base = TM_YEAR_BASE;
 339                                         yday = t->tm_yday;
 340                                         wday = t->tm_wday;
 341                                         for ( ; ; ) {
 342                                                 int     len;
 343                                                 int     bot;
 344                                                 int     top;
 345
 346                                                 len = isleap_sum(year, base) ?
 347                                                         DAYSPERLYEAR :
 348                                                         DAYSPERNYEAR;
 349                                                 /*
 350                                                 ** What yday (-3 ... 3) does
 351                                                 ** the ISO year begin on?
 352                                                 */
 353                                                 bot = ((yday + 11 - wday) %
 354                                                         DAYSPERWEEK) - 3;
 355                                                 /*
 356                                                 ** What yday does the NEXT
 357                                                 ** ISO year begin on?
 358                                                 */
 359                                                 top = bot -
 360                                                         (len % DAYSPERWEEK);
 361                                                 if (top < -3)
 362                                                         top += DAYSPERWEEK;
 363                                                 top += len;
 364                                                 if (yday >= top) {
 365                                                         ++base;
 366                                                         w = 1;
 367                                                         break;
 368                                                 }
 369                                                 if (yday >= bot) {
 370                                                         w = 1 + ((yday - bot) /
 371                                                                 DAYSPERWEEK);
 372                                                         break;
 373                                                 }
 374                                                 --base;
 375                                                 yday += isleap_sum(year, base) ?
 376                                                         DAYSPERLYEAR :
 377                                                         DAYSPERNYEAR;
 378                                         }
 379 #ifdef XPG4_1994_04_09
 380                                         if ((w == 52 &&
 381                                                 t->tm_mon == TM_JANUARY) ||
 382                                                 (w == 1 &&
 383                                                 t->tm_mon == TM_DECEMBER))
 384                                                         w = 53;
 385 #endif /* defined XPG4_1994_04_09 */
 386                                         if (*format == 'V')
 387                                                 pt = _conv(w, "%02d",
 388                                                         pt, ptlim);
 389                                         else if (*format == 'g') {
 390                                                 *warnp = IN_ALL;
 391                                                 pt = _yconv(year, base, 0, 1,
 392                                                         pt, ptlim);
 393                                         } else  pt = _yconv(year, base, 1, 1,
 394                                                         pt, ptlim);
 395                                 }
 396                                 continue;
 397                         case 'v':
 398                                 /*
 399                                 ** From Arnold Robbins' strftime version 3.0:
 400                                 ** "date as dd-bbb-YYYY"
 401                                 ** (ado, 1993-05-24)
 402                                 */
 403                                 pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
 404                                 continue;
 405                         case 'W':
 406                                 pt = _conv((t->tm_yday + DAYSPERWEEK -
 407                                         (t->tm_wday ?
 408                                         (t->tm_wday - 1) :
 409                                         (DAYSPERWEEK - 1))) / DAYSPERWEEK,
 410                                         "%02d", pt, ptlim);
 411                                 continue;
 412                         case 'w':
 413                                 pt = _conv(t->tm_wday, "%d", pt, ptlim);
 414                                 continue;
 415                         case 'X':
 416                                 pt = _fmt(Locale->t_fmt, t, pt, ptlim, warnp);
 417                                 continue;
 418                         case 'x':
 419                                 {
 420                                 int     warn2 = IN_SOME;
 421
 422                                 pt = _fmt(Locale->d_fmt, t, pt, ptlim, &warn2);
 423                                 if (warn2 == IN_ALL)
 424                                         warn2 = IN_THIS;
 425                                 if (warn2 > *warnp)
 426                                         *warnp = warn2;
 427                                 }
 428                                 continue;
 429                         case 'y':
 430                                 *warnp = IN_ALL;
 431                                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 0, 1,
 432                                         pt, ptlim);
 433                                 continue;
 434                         case 'Y':
 435                                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 1,
 436                                         pt, ptlim);
 437                                 continue;
 438                         case 'Z':
 439 #ifdef TM_ZONE
 440                                 if (t->TM_ZONE != NULL)
 441                                         pt = _add(t->TM_ZONE, pt, ptlim);
 442                                 else
 443 #endif /* defined TM_ZONE */
 444                                 if (t->tm_isdst >= 0)
 445                                         pt = _add(tzname[t->tm_isdst != 0],
 446                                                 pt, ptlim);
 447                                 /*
 448                                 ** C99 says that %Z must be replaced by the
 449                                 ** empty string if the time zone is not
 450                                 ** determinable.
 451                                 */
 452                                 continue;
 453                         case 'z':
 454                                 {
 455                                 int             diff;
 456                                 char const *    sign;
 457
 458                                 if (t->tm_isdst < 0)
 459                                         continue;
 460 #ifdef TM_GMTOFF
 461                                 diff = (int)t->TM_GMTOFF;
 462 #else /* !defined TM_GMTOFF */
 463                                 /*
 464                                 ** C99 says that the UTC offset must
 465                                 ** be computed by looking only at
 466                                 ** tm_isdst. This requirement is
 467                                 ** incorrect, since it means the code
 468                                 ** must rely on magic (in this case
 469                                 ** altzone and timezone), and the
 470                                 ** magic might not have the correct
 471                                 ** offset. Doing things correctly is
 472                                 ** tricky and requires disobeying C99;
 473                                 ** see GNU C strftime for details.
 474                                 ** For now, punt and conform to the
 475                                 ** standard, even though it's incorrect.
 476                                 **
 477                                 ** C99 says that %z must be replaced by the
 478                                 ** empty string if the time zone is not
 479                                 ** determinable, so output nothing if the
 480                                 ** appropriate variables are not available.
 481                                 */
 482                                 {
 483                                         struct tm tmp;
 484                                         time_t lct, gct;
 485
 486                                         /*
 487                                         ** Get calendar time from t
 488                                         ** being treated as local.
 489                                         */
 490                                         tmp = *t; /* mktime discards const */
 491                                         lct = mktime(&tmp);
 492
 493                                         if (lct == (time_t)-1)
 494                                                 continue;
 495
 496                                         /*
 497                                         ** Get calendar time from t
 498                                         ** being treated as GMT.
 499                                         **/
 500                                         tmp = *t; /* mktime discards const */
 501                                         gct = timegm(&tmp);
 502
 503                                         if (gct == (time_t)-1)
 504                                                 continue;
 505
 506                                         /* LINTED difference will fit int */
 507                                         diff = (intmax_t)gct - (intmax_t)lct;
 508                                 }
 509 #endif /* !defined TM_GMTOFF */
 510                                 if (diff < 0) {
 511                                         sign = "-";
 512                                         diff = -diff;
 513                                 } else  sign = "+";
 514                                 pt = _add(sign, pt, ptlim);
 515                                 diff /= SECSPERMIN;
 516                                 diff = (diff / MINSPERHOUR) * 100 +
 517                                         (diff % MINSPERHOUR);
 518                                 pt = _conv(diff, "%04d", pt, ptlim);
 519                                 }
 520                                 continue;
 521                         case '+':
 522                                 pt = _fmt(Locale->d_t_fmt, t, pt, ptlim,
 523                                         warnp);
 524                                 continue;
 525                         case '%':
 526                         /*
 527                         ** X311J/88-090 (4.12.3.5): if conversion char is
 528                         ** undefined, behavior is undefined. Print out the
 529                         ** character itself as printf(3) also does.
 530                         */
 531                         default:
 532                                 break;
 533                         }
 534                 }
 535                 if (pt == ptlim)
 536                         break;
 537                 *pt++ = *format;
 538         }
 539         return pt;
 540 }
 541
 542 static char *
 543 _conv(const int n, const char * const format, char * const pt,
 544       const char * const ptlim)
 545 {
 546         char    buf[INT_STRLEN_MAXIMUM(int) + 1];
 547
 548         snprintf(buf, sizeof(buf), format, n);
 549         return _add(buf, pt, ptlim);
 550 }
 551
 552 static char *
 553 _add(const char *str, char *pt, const char * const ptlim)
 554 {
 555         while (pt < ptlim && (*pt = *str++) != '\0')
 556                 ++pt;
 557         return pt;
 558 }
 559
 560 /*
 561 ** POSIX and the C Standard are unclear or inconsistent about
 562 ** what %C and %y do if the year is negative or exceeds 9999.
 563 ** Use the convention that %C concatenated with %y yields the
 564 ** same output as %Y, and that %Y contains at least 4 bytes,
 565 ** with more only if necessary.
 566 */
 567
 568 static char *
 569 _yconv(const int a, const int b, const int convert_top, const int convert_yy,
 570        char *pt, const char * const ptlim)
 571 {
 572         int     lead;
 573         int     trail;
 574
 575 #define DIVISOR 100
 576         trail = a % DIVISOR + b % DIVISOR;
 577         lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
 578         trail %= DIVISOR;
 579         if (trail < 0 && lead > 0) {
 580                 trail += DIVISOR;
 581                 --lead;
 582         } else if (lead < 0 && trail > 0) {
 583                 trail -= DIVISOR;
 584                 ++lead;
 585         }
 586         if (convert_top) {
 587                 if (lead == 0 && trail < 0)
 588                         pt = _add("-0", pt, ptlim);
 589                 else    pt = _conv(lead, "%02d", pt, ptlim);
 590         }
 591         if (convert_yy)
 592                 pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
 593         return pt;
 594 }