lib/libc/stdtime/strftime.c

   1 /*
   2  * Copyright (c) 1989 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms are permitted
   6  * provided that the above copyright notice and this paragraph are
   7  * duplicated in all such forms and that any documentation,
   8  * advertising materials, and other materials related to such
   9  * distribution and use acknowledge that the software was developed
  10  * by the University of California, Berkeley.  The name of the
  11  * University may not be used to endorse or promote products derived
  12  * from this software without specific prior written permission.
  13  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  16  */
  17
  18 #ifndef lint
  19 #ifndef NOID
  20 static const char       elsieid[] = "@(#)strftime.c     7.64";
  21 /*
  22 ** Based on the UCB version with the ID appearing below.
  23 ** This is ANSIish only when "multibyte character == plain character".
  24 */
  25 #endif /* !defined NOID */
  26 #endif /* !defined lint */
  27
  28 #include "namespace.h"
  29 #include "private.h"
  30
  31 #if defined(LIBC_SCCS) && !defined(lint)
  32 static const char       sccsid[] = "@(#)strftime.c      5.4 (Berkeley) 3/14/89";
  33 #endif /* LIBC_SCCS and not lint */
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD$");
  36
  37 #include "tzfile.h"
  38 #include <fcntl.h>
  39 #include <sys/stat.h>
  40 #include "un-namespace.h"
  41 #include "timelocal.h"
  42
  43 static char *   _add(const char *, char *, const char *);
  44 static char *   _conv(int, const char *, char *, const char *);
  45 static char *   _fmt(const char *, const struct tm *, char *, const char *, int *);
  46
  47 size_t strftime(char * __restrict, size_t, const char * __restrict,
  48     const struct tm * __restrict);
  49
  50 extern char *   tzname[];
  51
  52 #ifndef YEAR_2000_NAME
  53 #define YEAR_2000_NAME  "CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
  54 #endif /* !defined YEAR_2000_NAME */
  55
  56
  57 #define IN_NONE 0
  58 #define IN_SOME 1
  59 #define IN_THIS 2
  60 #define IN_ALL  3
  61
  62 #define PAD_DEFAULT 0
  63 #define PAD_LESS        1
  64 #define PAD_SPACE       2
  65 #define PAD_ZERO        3
  66
  67 static const char* fmt_padding[][4] = {
  68         /* DEFAULT,     LESS,   SPACE,  ZERO */
  69 #define PAD_FMT_MONTHDAY        0
  70 #define PAD_FMT_HMS                     0
  71 #define PAD_FMT_CENTURY         0
  72 #define PAD_FMT_SHORTYEAR       0
  73 #define PAD_FMT_MONTH           0
  74 #define PAD_FMT_WEEKOFYEAR      0
  75 #define PAD_FMT_DAYOFMONTH      0
  76         { "%02d",       "%d",   "%2d",  "%02d" },
  77 #define PAD_FMT_SDAYOFMONTH     1
  78 #define PAD_FMT_SHMS            1
  79         { "%2d",        "%d",   "%2d",  "%02d" },
  80 #define PAD_FMT_DAYOFYEAR       2
  81         { "%03d",       "%d",   "%3d",  "%03d" },
  82 #define PAD_FMT_YEAR            3
  83         { "%04d",       "%d",   "%4d",  "%04d" }
  84 };
  85
  86 size_t
  87 strftime(char * __restrict s, size_t maxsize, const char * __restrict format,
  88     const struct tm * __restrict t)
  89 {
  90         char *  p;
  91         int     warn;
  92
  93         tzset();
  94         warn = IN_NONE;
  95         p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn);
  96 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
  97         if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
  98                 (void) fprintf(stderr, "\n");
  99                 if (format == NULL)
 100                         (void) fprintf(stderr, "NULL strftime format ");
 101                 else    (void) fprintf(stderr, "strftime format \"%s\" ",
 102                                 format);
 103                 (void) fprintf(stderr, "yields only two digits of years in ");
 104                 if (warn == IN_SOME)
 105                         (void) fprintf(stderr, "some locales");
 106                 else if (warn == IN_THIS)
 107                         (void) fprintf(stderr, "the current locale");
 108                 else    (void) fprintf(stderr, "all locales");
 109                 (void) fprintf(stderr, "\n");
 110         }
 111 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
 112         if (p == s + maxsize)
 113                 return 0;
 114         *p = '\0';
 115         return p - s;
 116 }
 117
 118 static char *
 119 _fmt(format, t, pt, ptlim, warnp)
 120 const char *            format;
 121 const struct tm * const t;
 122 char *                  pt;
 123 const char * const      ptlim;
 124 int *                   warnp;
 125 {
 126         int Ealternative, Oalternative, PadIndex;
 127         struct lc_time_T *tptr = __get_current_time_locale();
 128
 129         for ( ; *format; ++format) {
 130                 if (*format == '%') {
 131                         Ealternative = 0;
 132                         Oalternative = 0;
 133                         PadIndex         = PAD_DEFAULT;
 134 label:
 135                         switch (*++format) {
 136                         case '\0':
 137                                 --format;
 138                                 break;
 139                         case 'A':
 140                                 pt = _add((t->tm_wday < 0 ||
 141                                         t->tm_wday >= DAYSPERWEEK) ?
 142                                         "?" : tptr->weekday[t->tm_wday],
 143                                         pt, ptlim);
 144                                 continue;
 145                         case 'a':
 146                                 pt = _add((t->tm_wday < 0 ||
 147                                         t->tm_wday >= DAYSPERWEEK) ?
 148                                         "?" : tptr->wday[t->tm_wday],
 149                                         pt, ptlim);
 150                                 continue;
 151                         case 'B':
 152                                 pt = _add((t->tm_mon < 0 ||
 153                                         t->tm_mon >= MONSPERYEAR) ?
 154                                         "?" : (Oalternative ? tptr->alt_month :
 155                                         tptr->month)[t->tm_mon],
 156                                         pt, ptlim);
 157                                 continue;
 158                         case 'b':
 159                         case 'h':
 160                                 pt = _add((t->tm_mon < 0 ||
 161                                         t->tm_mon >= MONSPERYEAR) ?
 162                                         "?" : tptr->mon[t->tm_mon],
 163                                         pt, ptlim);
 164                                 continue;
 165                         case 'C':
 166                                 /*
 167                                 ** %C used to do a...
 168                                 **      _fmt("%a %b %e %X %Y", t);
 169                                 ** ...whereas now POSIX 1003.2 calls for
 170                                 ** something completely different.
 171                                 ** (ado, 1993-05-24)
 172                                 */
 173                                 pt = _conv((t->tm_year + TM_YEAR_BASE) / 100,
 174                                         fmt_padding[PAD_FMT_CENTURY][PadIndex], pt, ptlim);
 175                                 continue;
 176                         case 'c':
 177                                 {
 178                                 int warn2 = IN_SOME;
 179
 180                                 pt = _fmt(tptr->c_fmt, t, pt, ptlim, warnp);
 181                                 if (warn2 == IN_ALL)
 182                                         warn2 = IN_THIS;
 183                                 if (warn2 > *warnp)
 184                                         *warnp = warn2;
 185                                 }
 186                                 continue;
 187                         case 'D':
 188                                 pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
 189                                 continue;
 190                         case 'd':
 191                                 pt = _conv(t->tm_mday, fmt_padding[PAD_FMT_DAYOFMONTH][PadIndex],
 192                                         pt, ptlim);
 193                                 continue;
 194                         case 'E':
 195                                 if (Ealternative || Oalternative)
 196                                         break;
 197                                 Ealternative++;
 198                                 goto label;
 199                         case 'O':
 200                                 /*
 201                                 ** C99 locale modifiers.
 202                                 ** The sequences
 203                                 **      %Ec %EC %Ex %EX %Ey %EY
 204                                 **      %Od %oe %OH %OI %Om %OM
 205                                 **      %OS %Ou %OU %OV %Ow %OW %Oy
 206                                 ** are supposed to provide alternate
 207                                 ** representations.
 208                                 **
 209                                 ** FreeBSD extension
 210                                 **      %OB
 211                                 */
 212                                 if (Ealternative || Oalternative)
 213                                         break;
 214                                 Oalternative++;
 215                                 goto label;
 216                         case 'e':
 217                                 pt = _conv(t->tm_mday,
 218                                         fmt_padding[PAD_FMT_SDAYOFMONTH][PadIndex], pt, ptlim);
 219                                 continue;
 220                         case 'F':
 221                                 pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
 222                                 continue;
 223                         case 'H':
 224                                 pt = _conv(t->tm_hour, fmt_padding[PAD_FMT_HMS][PadIndex],
 225                                         pt, ptlim);
 226                                 continue;
 227                         case 'I':
 228                                 pt = _conv((t->tm_hour % 12) ?
 229                                         (t->tm_hour % 12) : 12,
 230                                         fmt_padding[PAD_FMT_HMS][PadIndex], pt, ptlim);
 231                                 continue;
 232                         case 'j':
 233                                 pt = _conv(t->tm_yday + 1,
 234                                         fmt_padding[PAD_FMT_DAYOFYEAR][PadIndex], pt, ptlim);
 235                                 continue;
 236                         case 'k':
 237                                 /*
 238                                 ** This used to be...
 239                                 **      _conv(t->tm_hour % 12 ?
 240                                 **              t->tm_hour % 12 : 12, 2, ' ');
 241                                 ** ...and has been changed to the below to
 242                                 ** match SunOS 4.1.1 and Arnold Robbins'
 243                                 ** strftime version 3.0.  That is, "%k" and
 244                                 ** "%l" have been swapped.
 245                                 ** (ado, 1993-05-24)
 246                                 */
 247                                 pt = _conv(t->tm_hour, fmt_padding[PAD_FMT_SHMS][PadIndex],
 248                                         pt, ptlim);
 249                                 continue;
 250 #ifdef KITCHEN_SINK
 251                         case 'K':
 252                                 /*
 253                                 ** After all this time, still unclaimed!
 254                                 */
 255                                 pt = _add("kitchen sink", pt, ptlim);
 256                                 continue;
 257 #endif /* defined KITCHEN_SINK */
 258                         case 'l':
 259                                 /*
 260                                 ** This used to be...
 261                                 **      _conv(t->tm_hour, 2, ' ');
 262                                 ** ...and has been changed to the below to
 263                                 ** match SunOS 4.1.1 and Arnold Robbin's
 264                                 ** strftime version 3.0.  That is, "%k" and
 265                                 ** "%l" have been swapped.
 266                                 ** (ado, 1993-05-24)
 267                                 */
 268                                 pt = _conv((t->tm_hour % 12) ?
 269                                         (t->tm_hour % 12) : 12,
 270                                         fmt_padding[PAD_FMT_SHMS][PadIndex], pt, ptlim);
 271                                 continue;
 272                         case 'M':
 273                                 pt = _conv(t->tm_min, fmt_padding[PAD_FMT_HMS][PadIndex],
 274                                         pt, ptlim);
 275                                 continue;
 276                         case 'm':
 277                                 pt = _conv(t->tm_mon + 1,
 278                                         fmt_padding[PAD_FMT_MONTH][PadIndex], pt, ptlim);
 279                                 continue;
 280                         case 'n':
 281                                 pt = _add("\n", pt, ptlim);
 282                                 continue;
 283                         case 'p':
 284                                 pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
 285                                         tptr->pm :
 286                                         tptr->am,
 287                                         pt, ptlim);
 288                                 continue;
 289                         case 'R':
 290                                 pt = _fmt("%H:%M", t, pt, ptlim, warnp);
 291                                 continue;
 292                         case 'r':
 293                                 pt = _fmt(tptr->ampm_fmt, t, pt, ptlim,
 294                                         warnp);
 295                                 continue;
 296                         case 'S':
 297                                 pt = _conv(t->tm_sec, fmt_padding[PAD_FMT_HMS][PadIndex],
 298                                         pt, ptlim);
 299                                 continue;
 300                         case 's':
 301                                 {
 302                                         struct tm       tm;
 303                                         char            buf[INT_STRLEN_MAXIMUM(
 304                                                                 time_t) + 1];
 305                                         time_t          mkt;
 306
 307                                         tm = *t;
 308                                         mkt = mktime(&tm);
 309                                         if (TYPE_SIGNED(time_t))
 310                                                 (void) sprintf(buf, "%ld",
 311                                                         (long) mkt);
 312                                         else    (void) sprintf(buf, "%lu",
 313                                                         (unsigned long) mkt);
 314                                         pt = _add(buf, pt, ptlim);
 315                                 }
 316                                 continue;
 317                         case 'T':
 318                                 pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
 319                                 continue;
 320                         case 't':
 321                                 pt = _add("\t", pt, ptlim);
 322                                 continue;
 323                         case 'U':
 324                                 pt = _conv((t->tm_yday + DAYSPERWEEK -
 325                                         t->tm_wday) / DAYSPERWEEK,
 326                                         fmt_padding[PAD_FMT_WEEKOFYEAR][PadIndex], pt, ptlim);
 327                                 continue;
 328                         case 'u':
 329                                 /*
 330                                 ** From Arnold Robbins' strftime version 3.0:
 331                                 ** "ISO 8601: Weekday as a decimal number
 332                                 ** [1 (Monday) - 7]"
 333                                 ** (ado, 1993-05-24)
 334                                 */
 335                                 pt = _conv((t->tm_wday == 0) ?
 336                                         DAYSPERWEEK : t->tm_wday,
 337                                         "%d", pt, ptlim);
 338                                 continue;
 339                         case 'V':       /* ISO 8601 week number */
 340                         case 'G':       /* ISO 8601 year (four digits) */
 341                         case 'g':       /* ISO 8601 year (two digits) */
 342 /*
 343 ** From Arnold Robbins' strftime version 3.0:  "the week number of the
 344 ** year (the first Monday as the first day of week 1) as a decimal number
 345 ** (01-53)."
 346 ** (ado, 1993-05-24)
 347 **
 348 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
 349 ** "Week 01 of a year is per definition the first week which has the
 350 ** Thursday in this year, which is equivalent to the week which contains
 351 ** the fourth day of January. In other words, the first week of a new year
 352 ** is the week which has the majority of its days in the new year. Week 01
 353 ** might also contain days from the previous year and the week before week
 354 ** 01 of a year is the last week (52 or 53) of the previous year even if
 355 ** it contains days from the new year. A week starts with Monday (day 1)
 356 ** and ends with Sunday (day 7).  For example, the first week of the year
 357 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
 358 ** (ado, 1996-01-02)
 359 */
 360                                 {
 361                                         int     year;
 362                                         int     yday;
 363                                         int     wday;
 364                                         int     w;
 365
 366                                         year = t->tm_year + TM_YEAR_BASE;
 367                                         yday = t->tm_yday;
 368                                         wday = t->tm_wday;
 369                                         for ( ; ; ) {
 370                                                 int     len;
 371                                                 int     bot;
 372                                                 int     top;
 373
 374                                                 len = isleap(year) ?
 375                                                         DAYSPERLYEAR :
 376                                                         DAYSPERNYEAR;
 377                                                 /*
 378                                                 ** What yday (-3 ... 3) does
 379                                                 ** the ISO year begin on?
 380                                                 */
 381                                                 bot = ((yday + 11 - wday) %
 382                                                         DAYSPERWEEK) - 3;
 383                                                 /*
 384                                                 ** What yday does the NEXT
 385                                                 ** ISO year begin on?
 386                                                 */
 387                                                 top = bot -
 388                                                         (len % DAYSPERWEEK);
 389                                                 if (top < -3)
 390                                                         top += DAYSPERWEEK;
 391                                                 top += len;
 392                                                 if (yday >= top) {
 393                                                         ++year;
 394                                                         w = 1;
 395                                                         break;
 396                                                 }
 397                                                 if (yday >= bot) {
 398                                                         w = 1 + ((yday - bot) /
 399                                                                 DAYSPERWEEK);
 400                                                         break;
 401                                                 }
 402                                                 --year;
 403                                                 yday += isleap(year) ?
 404                                                         DAYSPERLYEAR :
 405                                                         DAYSPERNYEAR;
 406                                         }
 407 #ifdef XPG4_1994_04_09
 408                                         if ((w == 52
 409                                              && t->tm_mon == TM_JANUARY)
 410                                             || (w == 1
 411                                                 && t->tm_mon == TM_DECEMBER))
 412                                                 w = 53;
 413 #endif /* defined XPG4_1994_04_09 */
 414                                         if (*format == 'V')
 415                                                 pt = _conv(w, fmt_padding[PAD_FMT_WEEKOFYEAR][PadIndex],
 416                                                         pt, ptlim);
 417                                         else if (*format == 'g') {
 418                                                 *warnp = IN_ALL;
 419                                                 pt = _conv(year % 100, fmt_padding[PAD_FMT_SHORTYEAR][PadIndex],
 420                                                         pt, ptlim);
 421                                         } else  pt = _conv(year, fmt_padding[PAD_FMT_YEAR][PadIndex],
 422                                                         pt, ptlim);
 423                                 }
 424                                 continue;
 425                         case 'v':
 426                                 /*
 427                                 ** From Arnold Robbins' strftime version 3.0:
 428                                 ** "date as dd-bbb-YYYY"
 429                                 ** (ado, 1993-05-24)
 430                                 */
 431                                 pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
 432                                 continue;
 433                         case 'W':
 434                                 pt = _conv((t->tm_yday + DAYSPERWEEK -
 435                                         (t->tm_wday ?
 436                                         (t->tm_wday - 1) :
 437                                         (DAYSPERWEEK - 1))) / DAYSPERWEEK,
 438                                         fmt_padding[PAD_FMT_WEEKOFYEAR][PadIndex], pt, ptlim);
 439                                 continue;
 440                         case 'w':
 441                                 pt = _conv(t->tm_wday, "%d", pt, ptlim);
 442                                 continue;
 443                         case 'X':
 444                                 pt = _fmt(tptr->X_fmt, t, pt, ptlim, warnp);
 445                                 continue;
 446                         case 'x':
 447                                 {
 448                                 int     warn2 = IN_SOME;
 449
 450                                 pt = _fmt(tptr->x_fmt, t, pt, ptlim, &warn2);
 451                                 if (warn2 == IN_ALL)
 452                                         warn2 = IN_THIS;
 453                                 if (warn2 > *warnp)
 454                                         *warnp = warn2;
 455                                 }
 456                                 continue;
 457                         case 'y':
 458                                 *warnp = IN_ALL;
 459                                 pt = _conv((t->tm_year + TM_YEAR_BASE) % 100,
 460                                         fmt_padding[PAD_FMT_SHORTYEAR][PadIndex], pt, ptlim);
 461                                 continue;
 462                         case 'Y':
 463                                 pt = _conv(t->tm_year + TM_YEAR_BASE,
 464                                         fmt_padding[PAD_FMT_YEAR][PadIndex],
 465                                         pt, ptlim);
 466                                 continue;
 467                         case 'Z':
 468 #ifdef TM_ZONE
 469                                 if (t->TM_ZONE != NULL)
 470                                         pt = _add(t->TM_ZONE, pt, ptlim);
 471                                 else
 472 #endif /* defined TM_ZONE */
 473                                 if (t->tm_isdst >= 0)
 474                                         pt = _add(tzname[t->tm_isdst != 0],
 475                                                 pt, ptlim);
 476                                 /*
 477                                 ** C99 says that %Z must be replaced by the
 478                                 ** empty string if the time zone is not
 479                                 ** determinable.
 480                                 */
 481                                 continue;
 482                         case 'z':
 483                                 {
 484                                 int             diff;
 485                                 char const *    sign;
 486
 487                                 if (t->tm_isdst < 0)
 488                                         continue;
 489 #ifdef TM_GMTOFF
 490                                 diff = t->TM_GMTOFF;
 491 #else /* !defined TM_GMTOFF */
 492                                 /*
 493                                 ** C99 says that the UTC offset must
 494                                 ** be computed by looking only at
 495                                 ** tm_isdst.  This requirement is
 496                                 ** incorrect, since it means the code
 497                                 ** must rely on magic (in this case
 498                                 ** altzone and timezone), and the
 499                                 ** magic might not have the correct
 500                                 ** offset.  Doing things correctly is
 501                                 ** tricky and requires disobeying C99;
 502                                 ** see GNU C strftime for details.
 503                                 ** For now, punt and conform to the
 504                                 ** standard, even though it's incorrect.
 505                                 **
 506                                 ** C99 says that %z must be replaced by the
 507                                 ** empty string if the time zone is not
 508                                 ** determinable, so output nothing if the
 509                                 ** appropriate variables are not available.
 510                                 */
 511                                 if (t->tm_isdst == 0)
 512 #ifdef USG_COMPAT
 513                                         diff = -timezone;
 514 #else /* !defined USG_COMPAT */
 515                                         continue;
 516 #endif /* !defined USG_COMPAT */
 517                                 else
 518 #ifdef ALTZONE
 519                                         diff = -altzone;
 520 #else /* !defined ALTZONE */
 521                                         continue;
 522 #endif /* !defined ALTZONE */
 523 #endif /* !defined TM_GMTOFF */
 524                                 if (diff < 0) {
 525                                         sign = "-";
 526                                         diff = -diff;
 527                                 } else  sign = "+";
 528                                 pt = _add(sign, pt, ptlim);
 529                                 diff /= 60;
 530                                 pt = _conv((diff/60)*100 + diff%60,
 531                                         fmt_padding[PAD_FMT_YEAR][PadIndex], pt, ptlim);
 532                                 }
 533                                 continue;
 534                         case '+':
 535                                 pt = _fmt(tptr->date_fmt, t, pt, ptlim,
 536                                         warnp);
 537                                 continue;
 538                         case '-':
 539                                 if (PadIndex != PAD_DEFAULT)
 540                                         break;
 541                                 PadIndex = PAD_LESS;
 542                                 goto label;
 543                         case '_':
 544                                 if (PadIndex != PAD_DEFAULT)
 545                                         break;
 546                                 PadIndex = PAD_SPACE;
 547                                 goto label;
 548                         case '0':
 549                                 if (PadIndex != PAD_DEFAULT)
 550                                         break;
 551                                 PadIndex = PAD_ZERO;
 552                                 goto label;
 553                         case '%':
 554                         /*
 555                         ** X311J/88-090 (4.12.3.5): if conversion char is
 556                         ** undefined, behavior is undefined.  Print out the
 557                         ** character itself as printf(3) also does.
 558                         */
 559                         default:
 560                                 break;
 561                         }
 562                 }
 563                 if (pt == ptlim)
 564                         break;
 565                 *pt++ = *format;
 566         }
 567         return pt;
 568 }
 569
 570 static char *
 571 _conv(n, format, pt, ptlim)
 572 const int               n;
 573 const char * const      format;
 574 char * const            pt;
 575 const char * const      ptlim;
 576 {
 577         char    buf[INT_STRLEN_MAXIMUM(int) + 1];
 578
 579         (void) sprintf(buf, format, n);
 580         return _add(buf, pt, ptlim);
 581 }
 582
 583 static char *
 584 _add(str, pt, ptlim)
 585 const char *            str;
 586 char *                  pt;
 587 const char * const      ptlim;
 588 {
 589         while (pt < ptlim && (*pt = *str++) != '\0')
 590                 ++pt;
 591         return pt;
 592 }