git.zerfleddert.de Git - micropolis/blob - src/tclx/ossupp/strftime.c

   1 /*
   2  * strftime.c
   3  *
   4  * Public-domain relatively quick-and-dirty implemenation of
   5  * ANSI library routine for System V Unix systems.
   6  *
   7  * It's written in old-style C for maximal portability.
   8  *
   9  * The code for %c, %x, and %X is my best guess as to what's "appropriate".
  10  * This version ignores LOCALE information.
  11  * It also doesn't worry about multi-byte characters.
  12  * So there.
  13  *
  14  * Arnold Robbins
  15  * January, February, 1991
  16  *
  17  * Fixes from ado@elsie.nci.nih.gov
  18  * February 1991
  19  *-----------------------------------------------------------------------------
  20  * $Id: strftime.c,v 2.0 1992/10/16 04:52:16 markd Rel $
  21  *-----------------------------------------------------------------------------
  22  */
  23
  24 /*
  25  * To avoid Unix version problems, this code has been simplified to avoid
  26  * const and size_t, however this can cause an incompatible definition on
  27  * ansi-C systems, so a game is played with defines to ignore a strftime
  28  * declaration in time.h
  29  */
  30
  31 #define strftime ___srtftime
  32
  33 #include <stdio.h>
  34 #include <string.h>
  35 #include <time.h>
  36 #include <sys/types.h>
  37
  38 #undef strftime
  39
  40 extern char *strchr();
  41 static int weeknumber();
  42
  43 #ifndef TCL_HAS_TM_ZONE
  44 extern char *tzname[2];
  45 extern int daylight;
  46 #endif
  47
  48 /* strftime --- produce formatted time */
  49
  50 int
  51 strftime(s, maxsize, format, timeptr)
  52     char            *s;
  53     int              maxsize;
  54     char            *format;
  55     struct tm       *timeptr;
  56 {
  57         char *endp = s + maxsize;
  58         char *start = s;
  59         char tbuf[100];
  60         int i;
  61
  62         /* various tables, useful in North America */
  63         static char *days_a[] = {
  64                 "Sun", "Mon", "Tue", "Wed",
  65                 "Thu", "Fri", "Sat",
  66         };
  67         static char *days_l[] = {
  68                 "Sunday", "Monday", "Tuesday", "Wednesday",
  69                 "Thursday", "Friday", "Saturday",
  70         };
  71         static char *months_a[] = {
  72                 "Jan", "Feb", "Mar", "Apr", "May", "Jun",
  73                 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
  74         };
  75         static char *months_l[] = {
  76                 "January", "February", "March", "April",
  77                 "May", "June", "July", "August", "September",
  78                 "October", "November", "December",
  79         };
  80         static char *ampm[] = { "AM", "PM", };
  81
  82         if (s == NULL || format == NULL || timeptr == NULL || maxsize == 0)
  83                 return 0;
  84
  85         if (strchr(format, '%') == NULL && strlen(format) + 1 >= maxsize)
  86                 return 0;
  87
  88         for (; *format && s < endp - 1; format++) {
  89                 tbuf[0] = '\0';
  90                 if (*format != '%') {
  91                         *s++ = *format;
  92                         continue;
  93                 }
  94                 switch (*++format) {
  95                 case '\0':
  96                         *s++ = '%';
  97                         goto out;
  98
  99                 case '%':
 100                         *s++ = '%';
 101                         continue;
 102
 103                 case 'a':       /* abbreviated weekday name */
 104                         if (timeptr->tm_wday < 0 || timeptr->tm_wday > 6)
 105                                 strcpy(tbuf, "?");
 106                         else
 107                                 strcpy(tbuf, days_a[timeptr->tm_wday]);
 108                         break;
 109
 110                 case 'A':       /* full weekday name */
 111                         if (timeptr->tm_wday < 0 || timeptr->tm_wday > 6)
 112                                 strcpy(tbuf, "?");
 113                         else
 114                                 strcpy(tbuf, days_l[timeptr->tm_wday]);
 115                         break;
 116
 117                 case 'h':       /* abbreviated month name */
 118                 case 'b':       /* abbreviated month name */
 119                         if (timeptr->tm_mon < 0 || timeptr->tm_mon > 11)
 120                                 strcpy(tbuf, "?");
 121                         else
 122                                 strcpy(tbuf, months_a[timeptr->tm_mon]);
 123                         break;
 124
 125                 case 'B':       /* full month name */
 126                         if (timeptr->tm_mon < 0 || timeptr->tm_mon > 11)
 127                                 strcpy(tbuf, "?");
 128                         else
 129                                 strcpy(tbuf, months_l[timeptr->tm_mon]);
 130                         break;
 131
 132                 case 'c':       /* appropriate date and time representation */
 133                         sprintf(tbuf, "%s %s %2d %02d:%02d:%02d %d",
 134                                 days_a[timeptr->tm_wday],
 135                                 months_a[timeptr->tm_mon],
 136                                 timeptr->tm_mday,
 137                                 timeptr->tm_hour,
 138                                 timeptr->tm_min,
 139                                 timeptr->tm_sec,
 140                                 timeptr->tm_year + 1900);
 141                         break;
 142
 143                 case 'd':       /* day of the month, 01 - 31 */
 144                         sprintf(tbuf, "%02d", timeptr->tm_mday);
 145                         break;
 146
 147                 case 'H':       /* hour, 24-hour clock, 00 - 23 */
 148                         sprintf(tbuf, "%02d", timeptr->tm_hour);
 149                         break;
 150
 151                 case 'I':       /* hour, 12-hour clock, 01 - 12 */
 152                         i = timeptr->tm_hour;
 153                         if (i == 0)
 154                                 i = 12;
 155                         else if (i > 12)
 156                                 i -= 12;
 157                         sprintf(tbuf, "%02d", i);
 158                         break;
 159
 160                 case 'j':       /* day of the year, 001 - 366 */
 161                         sprintf(tbuf, "%03d", timeptr->tm_yday + 1);
 162                         break;
 163
 164                 case 'm':       /* month, 01 - 12 */
 165                         sprintf(tbuf, "%02d", timeptr->tm_mon + 1);
 166                         break;
 167
 168                 case 'M':       /* minute, 00 - 59 */
 169                         sprintf(tbuf, "%02d", timeptr->tm_min);
 170                         break;
 171
 172                 case 'p':       /* am or pm based on 12-hour clock */
 173                         if (timeptr->tm_hour < 12)
 174                                 strcpy(tbuf, ampm[0]);
 175                         else
 176                                 strcpy(tbuf, ampm[1]);
 177                         break;
 178
 179                 case 'S':       /* second, 00 - 61 */
 180                         sprintf(tbuf, "%02d", timeptr->tm_sec);
 181                         break;
 182
 183                 case 'U':       /* week of year, Sunday is first day of week */
 184                         sprintf(tbuf, "%d", weeknumber(timeptr, 0));
 185                         break;
 186
 187                 case 'w':       /* weekday, Sunday == 0, 0 - 6 */
 188                         sprintf(tbuf, "%d", timeptr->tm_wday);
 189                         break;
 190
 191                 case 'W':       /* week of year, Monday is first day of week */
 192                         sprintf(tbuf, "%d", weeknumber(timeptr, 1));
 193                         break;
 194
 195                 case 'x':       /* appropriate date representation */
 196                         sprintf(tbuf, "%s %s %2d %d",
 197                                 days_a[timeptr->tm_wday],
 198                                 months_a[timeptr->tm_mon],
 199                                 timeptr->tm_mday,
 200                                 timeptr->tm_year + 1900);
 201                         break;
 202
 203                 case 'X':       /* appropriate time representation */
 204                         sprintf(tbuf, "%02d:%02d:%02d",
 205                                 timeptr->tm_hour,
 206                                 timeptr->tm_min,
 207                                 timeptr->tm_sec);
 208                         break;
 209
 210                 case 'y':       /* year without a century, 00 - 99 */
 211                         i = timeptr->tm_year % 100;
 212                         sprintf(tbuf, "%d", i);
 213                         break;
 214
 215                 case 'Y':       /* year with century */
 216                         sprintf(tbuf, "%d", 1900 + timeptr->tm_year);
 217                         break;
 218
 219                 case 'Z':       /* time zone name or abbrevation */
 220 #ifdef TCL_HAS_TM_ZONE
 221                         strcpy(tbuf, timeptr->tm_zone);
 222 #else
 223                         i = 0;
 224                         if (daylight && timeptr->tm_isdst)
 225                                 i = 1;
 226                         strcpy(tbuf, tzname[i]);
 227 #endif
 228                         break;
 229
 230                 case 'n':       /* same as \n */
 231                         tbuf[0] = '\n';
 232                         tbuf[1] = '\0';
 233                         break;
 234
 235                 case 't':       /* same as \t */
 236                         tbuf[0] = '\t';
 237                         tbuf[1] = '\0';
 238                         break;
 239
 240                 case 'D':       /* date as %m/%d/%y */
 241                         strftime(tbuf, sizeof tbuf, "%m/%d/%y", timeptr);
 242                         break;
 243
 244                 case 'e':       /* day of month, blank padded */
 245                         sprintf(tbuf, "%2d", timeptr->tm_mday);
 246                         break;
 247
 248                 case 'r':       /* time as %I:%M:%S %p */
 249                         strftime(tbuf, sizeof tbuf, "%I:%M:%S %p", timeptr);
 250                         break;
 251
 252                 case 'R':       /* time as %H:%M */
 253                         strftime(tbuf, sizeof tbuf, "%H:%M", timeptr);
 254                         break;
 255
 256                 case 'T':       /* time as %H:%M:%S */
 257                         strftime(tbuf, sizeof tbuf, "%H:%M:%S", timeptr);
 258                         break;
 259
 260                 default:
 261                         tbuf[0] = '%';
 262                         tbuf[1] = *format;
 263                         tbuf[2] = '\0';
 264                         break;
 265                 }
 266                 i = strlen(tbuf);
 267                 if (i)
 268                         if (s + i < endp - 1) {
 269                                 strcpy(s, tbuf);
 270                                 s += i;
 271                         } else
 272                                 return 0;
 273         }
 274 out:
 275         if (s < endp && *format == '\0') {
 276                 *s = '\0';
 277                 return (s - start);
 278         } else
 279                 return 0;
 280 }
 281
 282 /* weeknumber --- figure how many weeks into the year */
 283
 284 /* With thanks and tip of the hatlo to ado@elsie.nci.nih.gov */
 285
 286 static int
 287 weeknumber(timeptr, firstweekday)
 288     struct tm *timeptr;
 289     int        firstweekday;
 290 {
 291         if (firstweekday == 0)
 292                 return (timeptr->tm_yday + 7 - timeptr->tm_wday) / 7;
 293         else
 294                 return (timeptr->tm_yday + 7 -
 295                         (timeptr->tm_wday ? (timeptr->tm_wday - 1) : 6)) / 7;
 296 }