time/strftime.c

   1 /* Copyright (C) 1991, 92, 93, 94, 95, 96 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #ifdef HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22
  23 #ifdef _LIBC
  24 # define HAVE_LIMITS_H 1
  25 # define HAVE_MBLEN 1
  26 # define HAVE_TM_ZONE 1
  27 # define STDC_HEADERS 1
  28 # include <ansidecl.h>
  29 # include "../locale/localeinfo.h"
  30 #endif
  31
  32 #include <stdio.h>
  33 #include <sys/types.h>          /* Some systems define `time_t' here.  */
  34
  35 #ifdef TIME_WITH_SYS_TIME
  36 # include <sys/time.h>
  37 # include <time.h>
  38 #else
  39 # ifdef HAVE_SYS_TIME_H
  40 #  include <sys/time.h>
  41 # else
  42 #  include <time.h>
  43 # endif
  44 #endif
  45
  46 #if HAVE_MBLEN
  47 # include <ctype.h>
  48 #endif
  49
  50 #if HAVE_LIMITS_H
  51 # include <limits.h>
  52 #endif
  53
  54 #if STDC_HEADERS
  55 # include <stddef.h>
  56 # include <stdlib.h>
  57 # include <string.h>
  58 #else
  59 # define memcpy(d, s, n) bcopy (s, d, n)
  60 #endif
  61
  62 #ifndef __P
  63 #if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
  64 #define __P(args) args
  65 #else
  66 #define __P(args) ()
  67 #endif  /* GCC.  */
  68 #endif  /* Not __P.  */
  69
  70 #ifndef PTR
  71 #ifdef __STDC__
  72 #define PTR void *
  73 #else
  74 #define PTR char *
  75 #endif
  76 #endif
  77
  78 static unsigned int week __P((const struct tm *const, int, int));
  79
  80
  81 #define add(n, f)                                                             \
  82   do                                                                          \
  83     {                                                                         \
  84       i += (n);                                                               \
  85       if (i >= maxsize)                                                       \
  86         return 0;                                                             \
  87       else                                                                    \
  88         if (p)                                                                \
  89           {                                                                   \
  90             f;                                                                \
  91             p += (n);                                                         \
  92           }                                                                   \
  93     } while (0)
  94 #define cpy(n, s)       add((n), memcpy((PTR) p, (PTR) (s), (n)))
  95
  96 #ifdef _LIBC
  97 #define fmt(n, args)    add((n), if (sprintf args != (n)) return 0)
  98 #else
  99 #define fmt(n, args)    add((n), sprintf args; if (strlen (p) != (n)) return 0)
 100 #endif
 101
 102
 103
 104 /* Return the week in the year specified by TP,
 105    with weeks starting on STARTING_DAY.  */
 106 #ifdef  __GNUC__
 107 inline
 108 #endif
 109 static unsigned int
 110 week (tp, starting_day, max_preceding)
 111       const struct tm *const tp;
 112       int starting_day;
 113       int max_preceding;
 114 {
 115   int wday, dl, base;
 116
 117   wday = tp->tm_wday - starting_day;
 118   if (wday < 0)
 119     wday += 7;
 120
 121   /* Set DL to the day in the year of the first day of the week
 122      containing the day specified in TP.  */
 123   dl = tp->tm_yday - wday;
 124
 125   /* For the computation following ISO 8601:1988 we set the number of
 126      the week containing January 1st to 1 if this week has more than
 127      MAX_PRECEDING days in the new year.  For ISO 8601 this number is
 128      3, for the other representation it is 7 (i.e., not to be
 129      fulfilled).  */
 130   base = ((dl + 7) % 7) > max_preceding ? 1 : 0;
 131
 132   /* If DL is negative we compute the result as 0 unless we have to
 133      compute it according ISO 8601.  In this case we have to return 53
 134      or 1 if the week containing January 1st has less than 4 days in
 135      the new year or not.  If DL is not negative we calculate the
 136      number of complete weeks for our week (DL / 7) plus 1 (because
 137      only for DL < 0 we are in week 0/53 and plus the number of the
 138      first week computed in the last step.  */
 139   return dl < 0 ? (dl < -max_preceding ? 53 : base)
 140                 : base + 1 + dl / 7;
 141 }
 142
 143 #ifndef _NL_CURRENT
 144 static char const weekday_name[][10] =
 145   {
 146     "Sunday", "Monday", "Tuesday", "Wednesday",
 147     "Thursday", "Friday", "Saturday"
 148   };
 149 static char const month_name[][10] =
 150   {
 151     "January", "February", "March", "April", "May", "June",
 152     "July", "August", "September", "October", "November", "December"
 153   };
 154 #endif
 155
 156 /* Write information from TP into S according to the format
 157    string FORMAT, writing no more that MAXSIZE characters
 158    (including the terminating '\0') and returning number of
 159    characters written.  If S is NULL, nothing will be written
 160    anywhere, so to determine how many characters would be
 161    written, use NULL for S and (size_t) UINT_MAX for MAXSIZE.  */
 162 size_t
 163 strftime (s, maxsize, format, tp)
 164       char *s;
 165       size_t maxsize;
 166       const char *format;
 167       register const struct tm *tp;
 168 {
 169   int hour12 = tp->tm_hour;
 170 #ifdef _NL_CURRENT
 171   const char *const a_wkday = _NL_CURRENT (LC_TIME, ABDAY_1 + tp->tm_wday);
 172   const char *const f_wkday = _NL_CURRENT (LC_TIME, DAY_1 + tp->tm_wday);
 173   const char *const a_month = _NL_CURRENT (LC_TIME, ABMON_1 + tp->tm_mon);
 174   const char *const f_month = _NL_CURRENT (LC_TIME, MON_1 + tp->tm_mon);
 175   const char *const ampm = _NL_CURRENT (LC_TIME,
 176                                         hour12 > 11 ? PM_STR : AM_STR);
 177   size_t aw_len = strlen(a_wkday);
 178   size_t am_len = strlen(a_month);
 179   size_t ap_len = strlen (ampm);
 180 #else
 181   const char *const f_wkday = weekday_name[tp->tm_wday];
 182   const char *const f_month = month_name[tp->tm_mon];
 183   const char *const a_wkday = f_wkday;
 184   const char *const a_month = f_month;
 185   const char *const ampm = "AMPM" + 2 * (hour12 > 11);
 186   size_t aw_len = 3;
 187   size_t am_len = 3;
 188   size_t ap_len = 2;
 189 #endif
 190   size_t wkday_len = strlen(f_wkday);
 191   size_t month_len = strlen(f_month);
 192   const unsigned int y_week0 = week (tp, 0, 7);
 193   const unsigned int y_week1 = week (tp, 1, 7);
 194   const unsigned int y_week2 = week (tp, 1, 3);
 195   const char *zone;
 196   size_t zonelen;
 197   register size_t i = 0;
 198   register char *p = s;
 199   register const char *f;
 200   char number_fmt[5];
 201
 202   /* Initialize the buffer we will use for the sprintf format for numbers.  */
 203   number_fmt[0] = '%';
 204
 205   zone = 0;
 206 #if HAVE_TM_ZONE
 207   zone = (const char *) tp->tm_zone;
 208 #endif
 209 #if HAVE_TZNAME
 210   if (!(zone && *zone) && tp->tm_isdst >= 0)
 211     zone = tzname[tp->tm_isdst];
 212 #endif
 213   if (!(zone && *zone))
 214     zone = "???";
 215
 216   zonelen = strlen (zone);
 217
 218   if (hour12 > 12)
 219     hour12 -= 12;
 220   else
 221     if (hour12 == 0) hour12 = 12;
 222
 223   for (f = format; *f != '\0'; ++f)
 224     {
 225       enum { pad_zero, pad_space, pad_none } pad; /* Padding for number.  */
 226       unsigned int maxdigits;   /* Max digits for numeric format.  */
 227       unsigned int number_value; /* Numeric value to be printed.  */
 228       const char *subfmt;
 229
 230 #if HAVE_MBLEN
 231       if (!isascii(*f))
 232         {
 233           /* Non-ASCII, may be a multibyte.  */
 234           int len = mblen(f, strlen(f));
 235           if (len > 0)
 236             {
 237               cpy(len, f);
 238               continue;
 239             }
 240         }
 241 #endif
 242
 243       if (*f != '%')
 244         {
 245           add(1, *p = *f);
 246           continue;
 247         }
 248
 249       /* Check for flags that can modify a number format.  */
 250       ++f;
 251       switch (*f)
 252         {
 253         case '_':
 254           pad = pad_space;
 255           ++f;
 256           break;
 257         case '-':
 258           pad = pad_none;
 259           ++f;
 260           break;
 261         default:
 262           pad = pad_zero;
 263           break;
 264         }
 265
 266       /* Now do the specified format.  */
 267       switch (*f)
 268         {
 269         case '\0':
 270         case '%':
 271           add(1, *p = *f);
 272           break;
 273
 274         case 'a':
 275           cpy(aw_len, a_wkday);
 276           break;
 277
 278         case 'A':
 279           cpy(wkday_len, f_wkday);
 280           break;
 281
 282         case 'b':
 283         case 'h':               /* GNU extension.  */
 284           cpy(am_len, a_month);
 285           break;
 286
 287         case 'B':
 288           cpy(month_len, f_month);
 289           break;
 290
 291         case 'c':
 292 #ifdef _NL_CURRENT
 293           subfmt = _NL_CURRENT (LC_TIME, D_T_FMT);
 294 #else
 295           subfmt = "%a %b %d %H:%M:%S %Z %Y";
 296 #endif
 297         subformat:
 298           {
 299             size_t len = strftime (p, maxsize - i, subfmt, tp);
 300             if (len == 0 && *subfmt)
 301               return 0;
 302             add(len, );
 303           }
 304           break;
 305
 306 #define DO_NUMBER(digits, value) \
 307           maxdigits = digits; number_value = value; goto do_number
 308 #define DO_NUMBER_NOPAD(digits, value) \
 309           maxdigits = digits; number_value = value; goto do_number_nopad
 310
 311         case 'C':
 312           DO_NUMBER (2, (1900 + tp->tm_year) / 100);
 313
 314         case 'x':
 315 #ifdef _NL_CURRENT
 316           subfmt = _NL_CURRENT (LC_TIME, D_FMT);
 317           goto subformat;
 318 #endif
 319           /* Fall through.  */
 320         case 'D':               /* GNU extension.  */
 321           subfmt = "%m/%d/%y";
 322           goto subformat;
 323
 324         case 'd':
 325           DO_NUMBER (2, tp->tm_mday);
 326
 327         case 'e':               /* GNU extension: %d, but blank-padded.  */
 328           DO_NUMBER_NOPAD (2, tp->tm_mday);
 329
 330           /* All numeric formats set MAXDIGITS and NUMBER_VALUE and then
 331              jump to one of these two labels.  */
 332
 333         do_number_nopad:
 334           /* Force `-' flag.  */
 335           pad = pad_none;
 336
 337         do_number:
 338           {
 339             /* Format the number according to the PAD flag.  */
 340
 341             register char *nf = &number_fmt[1];
 342             int printed;
 343
 344             switch (pad)
 345               {
 346               case pad_zero:
 347                 *nf++ = '0';
 348               case pad_space:
 349                 *nf++ = '0' + maxdigits;
 350               case pad_none:
 351                 *nf++ = 'u';
 352                 *nf = '\0';
 353               }
 354
 355 #ifdef _LIBC
 356             add (maxdigits, printed = sprintf (p, number_fmt, number_value));
 357 #else
 358             add (maxdigits, sprintf (p, number_fmt, number_value);
 359                  printed = strlen (p));
 360 #endif
 361
 362             break;
 363           }
 364
 365
 366         case 'H':
 367           DO_NUMBER (2, tp->tm_hour);
 368
 369         case 'I':
 370           DO_NUMBER (2, hour12);
 371
 372         case 'k':               /* GNU extension.  */
 373           DO_NUMBER_NOPAD (2, tp->tm_hour);
 374
 375         case 'l':               /* GNU extension.  */
 376           DO_NUMBER_NOPAD (2, hour12);
 377
 378         case 'j':
 379           DO_NUMBER (3, 1 + tp->tm_yday);
 380
 381         case 'M':
 382           DO_NUMBER (2, tp->tm_min);
 383
 384         case 'm':
 385           DO_NUMBER (2, tp->tm_mon + 1);
 386
 387         case 'n':               /* GNU extension.  */
 388           add (1, *p = '\n');
 389           break;
 390
 391         case 'p':
 392           cpy(ap_len, ampm);
 393           break;
 394
 395         case 'R':               /* GNU extension.  */
 396           subfmt = "%H:%M";
 397           goto subformat;
 398
 399         case 'r':               /* GNU extension.  */
 400           subfmt = "%I:%M:%S %p";
 401           goto subformat;
 402
 403         case 'S':
 404           DO_NUMBER (2, tp->tm_sec);
 405
 406         case 'X':
 407 #ifdef _NL_CURRENT
 408           subfmt = _NL_CURRENT (LC_TIME, T_FMT);
 409           goto subformat;
 410 #endif
 411           /* Fall through.  */
 412         case 'T':               /* GNU extenstion.  */
 413           subfmt = "%H:%M:%S";
 414           goto subformat;
 415
 416         case 't':               /* GNU extenstion.  */
 417           add (1, *p = '\t');
 418           break;
 419
 420         case 'U':
 421           DO_NUMBER (2, y_week0);
 422
 423         case 'V':
 424           DO_NUMBER (2, y_week2);
 425
 426         case 'W':
 427           DO_NUMBER (2, y_week1);
 428
 429         case 'w':
 430           DO_NUMBER (2, tp->tm_wday);
 431
 432         case 'Y':
 433           DO_NUMBER (4, 1900 + tp->tm_year);
 434
 435         case 'y':
 436           DO_NUMBER (2, tp->tm_year % 100);
 437
 438         case 'Z':
 439           cpy(zonelen, zone);
 440           break;
 441
 442         default:
 443           /* Bad format.  */
 444           break;
 445         }
 446     }
 447
 448   if (p)
 449     *p = '\0';
 450   return i;
 451 }