src/system/libroot/posix/time/strftime.c

   1 #ifndef lint
   2 #ifndef NOID
   3 static char     elsieid[] = "@(#)strftime.c     8.1";
   4 /*
   5 ** Based on the UCB version with the ID appearing below.
   6 ** This is ANSIish only when "multibyte character == plain character".
   7 */
   8 #endif /* !defined NOID */
   9 #endif /* !defined lint */
  10
  11 #include "private.h"
  12
  13 /*
  14 ** Copyright (c) 1989 The Regents of the University of California.
  15 ** All rights reserved.
  16 **
  17 ** Redistribution and use in source and binary forms are permitted
  18 ** provided that the above copyright notice and this paragraph are
  19 ** duplicated in all such forms and that any documentation,
  20 ** advertising materials, and other materials related to such
  21 ** distribution and use acknowledge that the software was developed
  22 ** by the University of California, Berkeley. The name of the
  23 ** University may not be used to endorse or promote products derived
  24 ** from this software without specific prior written permission.
  25 ** THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  26 ** IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  27 ** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  28 */
  29
  30 #ifndef LIBC_SCCS
  31 #ifndef lint
  32 static const char       sccsid[] = "@(#)strftime.c      5.4 (Berkeley) 3/14/89";
  33 #endif /* !defined lint */
  34 #endif /* !defined LIBC_SCCS */
  35
  36 #include "tzfile.h"
  37 #include "fcntl.h"
  38 #include "locale.h"
  39 #include "timelocal.h"
  40
  41 #define Locale __get_current_time_locale()
  42
  43 static char *   _add P((const char *, char *, const char *));
  44 static char *   _conv P((int, const char *, char *, const char *));
  45 static char *   _fmt P((const char *, const struct tm *, char *, const char *,
  46                         int *));
  47 static char *   _yconv P((int, int, int, int, char *, const char *));
  48
  49 extern char *   tzname[];
  50
  51 #ifndef YEAR_2000_NAME
  52 #define YEAR_2000_NAME  "CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
  53 #endif /* !defined YEAR_2000_NAME */
  54
  55 #define IN_NONE 0
  56 #define IN_SOME 1
  57 #define IN_THIS 2
  58 #define IN_ALL  3
  59
  60 #define NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
  61
  62 size_t
  63 strftime(s, maxsize, format, t)
  64 char * const            s;
  65 const size_t            maxsize;
  66 const char * const      format;
  67 const struct tm * const t;
  68 {
  69         char *  p;
  70         int     warn;
  71
  72         tzset();
  73         warn = IN_NONE;
  74         p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn);
  75 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
  76         if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
  77                 (void) fprintf(stderr, "\n");
  78                 if (format == NULL)
  79                         (void) fprintf(stderr, "NULL strftime format ");
  80                 else    (void) fprintf(stderr, "strftime format \"%s\" ",
  81                                 format);
  82                 (void) fprintf(stderr, "yields only two digits of years in ");
  83                 if (warn == IN_SOME)
  84                         (void) fprintf(stderr, "some locales");
  85                 else if (warn == IN_THIS)
  86                         (void) fprintf(stderr, "the current locale");
  87                 else    (void) fprintf(stderr, "all locales");
  88                 (void) fprintf(stderr, "\n");
  89         }
  90 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
  91         if (p == s + maxsize)
  92                 return 0;
  93         *p = '\0';
  94         return p - s;
  95 }
  96
  97 static char *
  98 _fmt(format, t, pt, ptlim, warnp)
  99 const char *            format;
 100 const struct tm * const t;
 101 char *                  pt;
 102 const char * const      ptlim;
 103 int *                   warnp;
 104 {
 105         for ( ; *format; ++format) {
 106                 if (*format == '%') {
 107 label:
 108                         switch (*++format) {
 109                         case '\0':
 110                                 --format;
 111                                 break;
 112                         case '0':
 113                                 // ignore '0'-modifier supported by glibc for compatibility
 114                                 goto label;
 115                         case 'A':
 116                                 pt = _add((t->tm_wday < 0 ||
 117                                         t->tm_wday >= DAYSPERWEEK) ?
 118                                         "?" : Locale->weekday[t->tm_wday],
 119                                         pt, ptlim);
 120                                 continue;
 121                         case 'a':
 122                                 pt = _add((t->tm_wday < 0 ||
 123                                         t->tm_wday >= DAYSPERWEEK) ?
 124                                         "?" : Locale->wday[t->tm_wday],
 125                                         pt, ptlim);
 126                                 continue;
 127                         case 'B':
 128                                 pt = _add((t->tm_mon < 0 ||
 129                                         t->tm_mon >= MONSPERYEAR) ?
 130                                         "?" : Locale->month[t->tm_mon],
 131                                         pt, ptlim);
 132                                 continue;
 133                         case 'b':
 134                         case 'h':
 135                                 pt = _add((t->tm_mon < 0 ||
 136                                         t->tm_mon >= MONSPERYEAR) ?
 137                                         "?" : Locale->mon[t->tm_mon],
 138                                         pt, ptlim);
 139                                 continue;
 140                         case 'C':
 141                                 /*
 142                                 ** %C used to do a...
 143                                 **      _fmt("%a %b %e %X %Y", t);
 144                                 ** ...whereas now POSIX 1003.2 calls for
 145                                 ** something completely different.
 146                                 ** (ado, 1993-05-24)
 147                                 */
 148                                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 0,
 149                                         pt, ptlim);
 150                                 continue;
 151                         case 'c':
 152                                 {
 153                                 int warn2 = IN_SOME;
 154
 155                                 pt = _fmt(Locale->c_fmt, t, pt, ptlim, warnp);
 156                                 if (warn2 > *warnp)
 157                                         *warnp = warn2;
 158                                 }
 159                                 continue;
 160                         case 'D':
 161                                 pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
 162                                 continue;
 163                         case 'd':
 164                                 pt = _conv(t->tm_mday, "%02d", pt, ptlim);
 165                                 continue;
 166                         case 'E':
 167                         case 'O':
 168                                 /*
 169                                 ** C99 locale modifiers.
 170                                 ** The sequences
 171                                 **      %Ec %EC %Ex %EX %Ey %EY
 172                                 **      %Od %oe %OH %OI %Om %OM
 173                                 **      %OS %Ou %OU %OV %Ow %OW %Oy
 174                                 ** are supposed to provide alternate
 175                                 ** representations.
 176                                 */
 177                                 goto label;
 178                         case 'e':
 179                                 pt = _conv(t->tm_mday, "%2d", pt, ptlim);
 180                                 continue;
 181                         case 'F':
 182                                 pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
 183                                 continue;
 184                         case 'H':
 185                                 pt = _conv(t->tm_hour, "%02d", pt, ptlim);
 186                                 continue;
 187                         case 'I':
 188                                 pt = _conv((t->tm_hour % 12) ?
 189                                         (t->tm_hour % 12) : 12,
 190                                         "%02d", pt, ptlim);
 191                                 continue;
 192                         case 'j':
 193                                 pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
 194                                 continue;
 195                         case 'k':
 196                                 /*
 197                                 ** This used to be...
 198                                 **      _conv(t->tm_hour % 12 ?
 199                                 **              t->tm_hour % 12 : 12, 2, ' ');
 200                                 ** ...and has been changed to the below to
 201                                 ** match SunOS 4.1.1 and Arnold Robbins'
 202                                 ** strftime version 3.0. That is, "%k" and
 203                                 ** "%l" have been swapped.
 204                                 ** (ado, 1993-05-24)
 205                                 */
 206                                 pt = _conv(t->tm_hour, "%2d", pt, ptlim);
 207                                 continue;
 208 #ifdef KITCHEN_SINK
 209                         case 'K':
 210                                 /*
 211                                 ** After all this time, still unclaimed!
 212                                 */
 213                                 pt = _add("kitchen sink", pt, ptlim);
 214                                 continue;
 215 #endif /* defined KITCHEN_SINK */
 216                         case 'l':
 217                                 /*
 218                                 ** This used to be...
 219                                 **      _conv(t->tm_hour, 2, ' ');
 220                                 ** ...and has been changed to the below to
 221                                 ** match SunOS 4.1.1 and Arnold Robbin's
 222                                 ** strftime version 3.0. That is, "%k" and
 223                                 ** "%l" have been swapped.
 224                                 ** (ado, 1993-05-24)
 225                                 */
 226                                 pt = _conv((t->tm_hour % 12) ?
 227                                         (t->tm_hour % 12) : 12,
 228                                         "%2d", pt, ptlim);
 229                                 continue;
 230                         case 'M':
 231                                 pt = _conv(t->tm_min, "%02d", pt, ptlim);
 232                                 continue;
 233                         case 'm':
 234                                 pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
 235                                 continue;
 236                         case 'n':
 237                                 pt = _add("\n", pt, ptlim);
 238                                 continue;
 239                         case 'p':
 240                                 pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
 241                                         Locale->pm :
 242                                         Locale->am,
 243                                         pt, ptlim);
 244                                 continue;
 245                         case 'R':
 246                                 pt = _fmt("%H:%M", t, pt, ptlim, warnp);
 247                                 continue;
 248                         case 'r':
 249                                 pt = _fmt("%I:%M:%S %p", t, pt, ptlim, warnp);
 250                                 continue;
 251                         case 'S':
 252                                 pt = _conv(t->tm_sec, "%02d", pt, ptlim);
 253                                 continue;
 254                         case 's':
 255                                 {
 256                                         struct tm       tm;
 257                                         char            buf[INT_STRLEN_MAXIMUM(
 258                                                                 time_t) + 1];
 259                                         time_t          mkt;
 260
 261                                         tm = *t;
 262                                         mkt = mktime(&tm);
 263                                         if (TYPE_SIGNED(time_t))
 264                                                 (void) sprintf(buf, "%ld",
 265                                                         (long) mkt);
 266                                         else    (void) sprintf(buf, "%lu",
 267                                                         (unsigned long) mkt);
 268                                         pt = _add(buf, pt, ptlim);
 269                                 }
 270                                 continue;
 271                         case 'T':
 272                                 pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
 273                                 continue;
 274                         case 't':
 275                                 pt = _add("\t", pt, ptlim);
 276                                 continue;
 277                         case 'U':
 278                                 pt = _conv((t->tm_yday + DAYSPERWEEK -
 279                                         t->tm_wday) / DAYSPERWEEK,
 280                                         "%02d", pt, ptlim);
 281                                 continue;
 282                         case 'u':
 283                                 /*
 284                                 ** From Arnold Robbins' strftime version 3.0:
 285                                 ** "ISO 8601: Weekday as a decimal number
 286                                 ** [1 (Monday) - 7]"
 287                                 ** (ado, 1993-05-24)
 288                                 */
 289                                 pt = _conv((t->tm_wday == 0) ?
 290                                         DAYSPERWEEK : t->tm_wday,
 291                                         "%d", pt, ptlim);
 292                                 continue;
 293                         case 'V':       /* ISO 8601 week number */
 294                         case 'G':       /* ISO 8601 year (four digits) */
 295                         case 'g':       /* ISO 8601 year (two digits) */
 296 /*
 297 ** From Arnold Robbins' strftime version 3.0: "the week number of the
 298 ** year (the first Monday as the first day of week 1) as a decimal number
 299 ** (01-53)."
 300 ** (ado, 1993-05-24)
 301 **
 302 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
 303 ** "Week 01 of a year is per definition the first week which has the
 304 ** Thursday in this year, which is equivalent to the week which contains
 305 ** the fourth day of January. In other words, the first week of a new year
 306 ** is the week which has the majority of its days in the new year. Week 01
 307 ** might also contain days from the previous year and the week before week
 308 ** 01 of a year is the last week (52 or 53) of the previous year even if
 309 ** it contains days from the new year. A week starts with Monday (day 1)
 310 ** and ends with Sunday (day 7). For example, the first week of the year
 311 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
 312 ** (ado, 1996-01-02)
 313 */
 314                                 {
 315                                         int     year;
 316                                         int     base;
 317                                         int     yday;
 318                                         int     wday;
 319                                         int     w;
 320
 321                                         year = t->tm_year;
 322                                         base = TM_YEAR_BASE;
 323                                         yday = t->tm_yday;
 324                                         wday = t->tm_wday;
 325                                         for ( ; ; ) {
 326                                                 int     len;
 327                                                 int     bot;
 328                                                 int     top;
 329
 330                                                 len = isleap_sum(year, base) ?
 331                                                         DAYSPERLYEAR :
 332                                                         DAYSPERNYEAR;
 333                                                 /*
 334                                                 ** What yday (-3 ... 3) does
 335                                                 ** the ISO year begin on?
 336                                                 */
 337                                                 bot = ((yday + 11 - wday) %
 338                                                         DAYSPERWEEK) - 3;
 339                                                 /*
 340                                                 ** What yday does the NEXT
 341                                                 ** ISO year begin on?
 342                                                 */
 343                                                 top = bot -
 344                                                         (len % DAYSPERWEEK);
 345                                                 if (top < -3)
 346                                                         top += DAYSPERWEEK;
 347                                                 top += len;
 348                                                 if (yday >= top) {
 349                                                         ++base;
 350                                                         w = 1;
 351                                                         break;
 352                                                 }
 353                                                 if (yday >= bot) {
 354                                                         w = 1 + ((yday - bot) /
 355                                                                 DAYSPERWEEK);
 356                                                         break;
 357                                                 }
 358                                                 --base;
 359                                                 yday += isleap_sum(year, base) ?
 360                                                         DAYSPERLYEAR :
 361                                                         DAYSPERNYEAR;
 362                                         }
 363 #ifdef XPG4_1994_04_09
 364                                         if ((w == 52 &&
 365                                                 t->tm_mon == TM_JANUARY) ||
 366                                                 (w == 1 &&
 367                                                 t->tm_mon == TM_DECEMBER))
 368                                                         w = 53;
 369 #endif /* defined XPG4_1994_04_09 */
 370                                         if (*format == 'V')
 371                                                 pt = _conv(w, "%02d",
 372                                                         pt, ptlim);
 373                                         else if (*format == 'g') {
 374                                                 *warnp = IN_ALL;
 375                                                 pt = _yconv(year, base, 0, 1,
 376                                                         pt, ptlim);
 377                                         } else  pt = _yconv(year, base, 1, 1,
 378                                                         pt, ptlim);
 379                                 }
 380                                 continue;
 381                         case 'v':
 382                                 /*
 383                                 ** From Arnold Robbins' strftime version 3.0:
 384                                 ** "date as dd-bbb-YYYY"
 385                                 ** (ado, 1993-05-24)
 386                                 */
 387                                 pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
 388                                 continue;
 389                         case 'W':
 390                                 pt = _conv((t->tm_yday + DAYSPERWEEK -
 391                                         (t->tm_wday ?
 392                                         (t->tm_wday - 1) :
 393                                         (DAYSPERWEEK - 1))) / DAYSPERWEEK,
 394                                         "%02d", pt, ptlim);
 395                                 continue;
 396                         case 'w':
 397                                 pt = _conv(t->tm_wday, "%d", pt, ptlim);
 398                                 continue;
 399                         case 'X':
 400                                 pt = _fmt(Locale->X_fmt, t, pt, ptlim, warnp);
 401                                 continue;
 402                         case 'x':
 403                                 {
 404                                 int     warn2 = IN_SOME;
 405
 406                                 pt = _fmt(Locale->x_fmt, t, pt, ptlim, &warn2);
 407                                 if (warn2 == IN_ALL)
 408                                         warn2 = IN_THIS;
 409                                 if (warn2 > *warnp)
 410                                         *warnp = warn2;
 411                                 }
 412                                 continue;
 413                         case 'y':
 414                                 *warnp = IN_ALL;
 415                                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 0, 1,
 416                                         pt, ptlim);
 417                                 continue;
 418                         case 'Y':
 419                                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 1,
 420                                         pt, ptlim);
 421                                 continue;
 422                         case 'Z':
 423 #ifdef TM_ZONE
 424                                 if (t->TM_ZONE != NULL)
 425                                         pt = _add(t->TM_ZONE, pt, ptlim);
 426                                 else
 427 #endif /* defined TM_ZONE */
 428                                 if (t->tm_isdst >= 0)
 429                                         pt = _add(tzname[t->tm_isdst != 0],
 430                                                 pt, ptlim);
 431                                 /*
 432                                 ** C99 says that %Z must be replaced by the
 433                                 ** empty string if the time zone is not
 434                                 ** determinable.
 435                                 */
 436                                 continue;
 437                         case 'z':
 438                                 {
 439                                 int             diff;
 440                                 char const *    sign;
 441
 442                                 if (t->tm_isdst < 0)
 443                                         continue;
 444 #ifdef TM_GMTOFF
 445                                 diff = t->TM_GMTOFF;
 446 #else /* !defined TM_GMTOFF */
 447                                 /*
 448                                 ** C99 says that the UTC offset must
 449                                 ** be computed by looking only at
 450                                 ** tm_isdst. This requirement is
 451                                 ** incorrect, since it means the code
 452                                 ** must rely on magic (in this case
 453                                 ** altzone and timezone), and the
 454                                 ** magic might not have the correct
 455                                 ** offset. Doing things correctly is
 456                                 ** tricky and requires disobeying C99;
 457                                 ** see GNU C strftime for details.
 458                                 ** For now, punt and conform to the
 459                                 ** standard, even though it's incorrect.
 460                                 **
 461                                 ** C99 says that %z must be replaced by the
 462                                 ** empty string if the time zone is not
 463                                 ** determinable, so output nothing if the
 464                                 ** appropriate variables are not available.
 465                                 */
 466                                 if (t->tm_isdst == 0)
 467 #ifdef USG_COMPAT
 468                                         diff = -timezone;
 469 #else /* !defined USG_COMPAT */
 470                                         continue;
 471 #endif /* !defined USG_COMPAT */
 472                                 else
 473 #ifdef ALTZONE
 474                                         diff = -altzone;
 475 #else /* !defined ALTZONE */
 476                                         continue;
 477 #endif /* !defined ALTZONE */
 478 #endif /* !defined TM_GMTOFF */
 479                                 if (diff < 0) {
 480                                         sign = "-";
 481                                         diff = -diff;
 482                                 } else  sign = "+";
 483                                 pt = _add(sign, pt, ptlim);
 484                                 diff /= SECSPERMIN;
 485                                 diff = (diff / MINSPERHOUR) * 100 +
 486                                         (diff % MINSPERHOUR);
 487                                 pt = _conv(diff, "%04d", pt, ptlim);
 488                                 }
 489                                 continue;
 490                         case '+':
 491                                 pt = _fmt(Locale->date_fmt, t, pt, ptlim,
 492                                         warnp);
 493                                 continue;
 494                         case '%':
 495                         /*
 496                         ** X311J/88-090 (4.12.3.5): if conversion char is
 497                         ** undefined, behavior is undefined. Print out the
 498                         ** character itself as printf(3) also does.
 499                         */
 500                         default:
 501                                 break;
 502                         }
 503                 }
 504                 if (pt == ptlim)
 505                         break;
 506                 *pt++ = *format;
 507         }
 508         return pt;
 509 }
 510
 511 static char *
 512 _conv(n, format, pt, ptlim)
 513 const int               n;
 514 const char * const      format;
 515 char * const            pt;
 516 const char * const      ptlim;
 517 {
 518         char    buf[INT_STRLEN_MAXIMUM(int) + 1];
 519
 520         (void) sprintf(buf, format, n);
 521         return _add(buf, pt, ptlim);
 522 }
 523
 524 static char *
 525 _add(str, pt, ptlim)
 526 const char *            str;
 527 char *                  pt;
 528 const char * const      ptlim;
 529 {
 530         while (pt < ptlim && (*pt = *str++) != '\0')
 531                 ++pt;
 532         return pt;
 533 }
 534
 535 /*
 536 ** POSIX and the C Standard are unclear or inconsistent about
 537 ** what %C and %y do if the year is negative or exceeds 9999.
 538 ** Use the convention that %C concatenated with %y yields the
 539 ** same output as %Y, and that %Y contains at least 4 bytes,
 540 ** with more only if necessary.
 541 */
 542
 543 static char *
 544 _yconv(a, b, convert_top, convert_yy, pt, ptlim)
 545 const int               a;
 546 const int               b;
 547 const int               convert_top;
 548 const int               convert_yy;
 549 char *                  pt;
 550 const char * const      ptlim;
 551 {
 552         register int    lead;
 553         register int    trail;
 554
 555 #define DIVISOR 100
 556         trail = a % DIVISOR + b % DIVISOR;
 557         lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
 558         trail %= DIVISOR;
 559         if (trail < 0 && lead > 0) {
 560                 trail += DIVISOR;
 561                 --lead;
 562         } else if (lead < 0 && trail > 0) {
 563                 trail -= DIVISOR;
 564                 ++lead;
 565         }
 566         if (convert_top) {
 567                 if (lead == 0 && trail < 0)
 568                         pt = _add("-0", pt, ptlim);
 569                 else    pt = _conv(lead, "%02d", pt, ptlim);
 570         }
 571         if (convert_yy)
 572                 pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
 573         return pt;
 574 }