diplodocus.org Git - nmh/blob - sbr/dtime.c

   1 /* dtime.c -- time/date routines
   2  *
   3  * This code is Copyright (c) 2002, by the authors of nmh.  See the
   4  * COPYRIGHT file in the root directory of the nmh distribution for
   5  * complete copyright information.
   6  */
   7
   8 #include <h/mh.h>   /* for snprintf() */
   9 #include <h/nmh.h>
  10 #include <h/tws.h>
  11 #include <time.h>
  12
  13 #if !defined(HAVE_STRUCT_TM_TM_GMTOFF)
  14 extern long timezone;
  15 #endif
  16
  17 /*
  18  * The number of days in the year, accounting for leap years
  19  */
  20 #define dysize(y)       \
  21         (((y) % 4) ? 365 : (((y) % 100) ? 366 : (((y) % 400) ? 365 : 366)))
  22
  23 char *tw_moty[] = {
  24     "Jan", "Feb", "Mar", "Apr",
  25     "May", "Jun", "Jul", "Aug",
  26     "Sep", "Oct", "Nov", "Dec",
  27     NULL
  28 };
  29
  30 char *tw_dotw[] = {
  31     "Sun", "Mon", "Tue",
  32     "Wed", "Thu", "Fri",
  33     "Sat", NULL
  34 };
  35
  36 char *tw_ldotw[] = {
  37     "Sunday",    "Monday",   "Tuesday",
  38     "Wednesday", "Thursday", "Friday",
  39     "Saturday",  NULL
  40 };
  41
  42 static int dmsize[] = {
  43     31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
  44 };
  45
  46
  47 /*
  48  * Get current time (adjusted for local time
  49  * zone and daylight savings time) expressed
  50  * as nmh "broken-down" time structure.
  51  */
  52
  53 struct tws *
  54 dlocaltimenow (void)
  55 {
  56     time_t clock;
  57
  58     time (&clock);
  59     return dlocaltime (&clock);
  60 }
  61
  62
  63 /*
  64  * Take clock value and return pointer to nmh time structure
  65  * containing "broken-down" time.  The time is adjusted for
  66  * local time zone and daylight savings time.
  67  */
  68
  69 struct tws *
  70 dlocaltime (time_t *clock)
  71 {
  72     static struct tws tw;
  73     struct tm *tm;
  74
  75     if (!clock)
  76         return NULL;
  77
  78     tm = localtime (clock);
  79
  80     tw.tw_sec  = tm->tm_sec;
  81     tw.tw_min  = tm->tm_min;
  82     tw.tw_hour = tm->tm_hour;
  83     tw.tw_mday = tm->tm_mday;
  84     tw.tw_mon  = tm->tm_mon;
  85
  86     /*
  87      * tm_year is always "year - 1900".
  88      * So we correct for this.
  89      */
  90     tw.tw_year = tm->tm_year + 1900;
  91     tw.tw_wday = tm->tm_wday;
  92     tw.tw_yday = tm->tm_yday;
  93
  94     tw.tw_flags = TW_NULL;
  95     if (tm->tm_isdst)
  96         tw.tw_flags |= TW_DST;
  97
  98 #ifdef HAVE_STRUCT_TM_TM_GMTOFF
  99     tw.tw_zone = tm->tm_gmtoff / 60;
 100     if (tm->tm_isdst)                   /* if DST is in effect */
 101         tw.tw_zone -= 60;               /* reset to normal offset */
 102 #else
 103     {
 104         static bool deja_vu;
 105
 106         if (!deja_vu) {
 107             deja_vu = true;
 108             tzset();
 109         }
 110     }
 111     tw.tw_zone = -(timezone / 60);
 112 #endif
 113
 114     tw.tw_flags &= ~TW_SDAY;
 115     tw.tw_flags |= TW_SEXP;
 116     tw.tw_flags |= TW_SZEXP;
 117
 118     tw.tw_clock = *clock;
 119
 120     return (&tw);
 121 }
 122
 123
 124 /*
 125  * Take clock value and return pointer to nmh time
 126  * structure containing "broken-down" time.  Time is
 127  * expressed in UTC (Coordinated Universal Time).
 128  */
 129
 130 struct tws *
 131 dgmtime (time_t *clock)
 132 {
 133     static struct tws tw;
 134     struct tm *tm;
 135
 136     if (!clock)
 137         return NULL;
 138
 139     tm = gmtime (clock);
 140
 141     tw.tw_sec  = tm->tm_sec;
 142     tw.tw_min  = tm->tm_min;
 143     tw.tw_hour = tm->tm_hour;
 144     tw.tw_mday = tm->tm_mday;
 145     tw.tw_mon  = tm->tm_mon;
 146
 147     /*
 148      * tm_year is always "year - 1900"
 149      * So we correct for this.
 150      */
 151     tw.tw_year = tm->tm_year + 1900;
 152     tw.tw_wday = tm->tm_wday;
 153     tw.tw_yday = tm->tm_yday;
 154
 155     tw.tw_flags = TW_NULL;
 156     if (tm->tm_isdst)
 157         tw.tw_flags |= TW_DST;
 158
 159     tw.tw_zone = 0;
 160
 161     tw.tw_flags &= ~TW_SDAY;
 162     tw.tw_flags |= TW_SEXP;
 163     tw.tw_flags |= TW_SZEXP;
 164
 165     tw.tw_clock = *clock;
 166
 167     return (&tw);
 168 }
 169
 170
 171 /*
 172  * Using a nmh "broken-down" time structure,
 173  * produce a 26-byte date/time string, such as
 174  *
 175  *      Tue Jan 14 17:49:03 1992\n\0
 176  */
 177
 178 char *
 179 dctime (struct tws *tw)
 180 {
 181     static char buffer[26];
 182
 183     if (!tw)
 184         return NULL;
 185
 186     snprintf (buffer, sizeof(buffer), "%.3s %.3s %02d %02d:%02d:%02d %.4d\n",
 187             tw_dotw[tw->tw_wday], tw_moty[tw->tw_mon], tw->tw_mday,
 188             tw->tw_hour, tw->tw_min, tw->tw_sec,
 189             tw->tw_year < 100 ? tw->tw_year + 1900 : tw->tw_year);
 190
 191     return buffer;
 192 }
 193
 194
 195 /*
 196  * Produce a date/time string of the form
 197  *
 198  *      Mon, 16 Jun 1992 15:30:48 -700 (or)
 199  *      Mon, 16 Jun 1992 15:30:48 EDT
 200  *
 201  * for the current time, as specified by RFC 822.
 202  * The first form is required by RFC 1123.
 203  */
 204
 205 char *
 206 dtimenow (int alpha_timezone)
 207 {
 208     time_t clock;
 209
 210     time (&clock);
 211     return dtime (&clock, alpha_timezone);
 212 }
 213
 214
 215 /*
 216  * Using a local calendar time value, produce
 217  * a date/time string of the form
 218  *
 219  *      Mon, 16 Jun 1992 15:30:48 -700  (or)
 220  *      Mon, 16 Jun 1992 15:30:48 EDT
 221  *
 222  * as specified by RFC 822.  The first form is required
 223  * by RFC 1123 for outgoing messages.
 224  */
 225
 226 char *
 227 dtime (time_t *clock, int alpha_timezone)
 228 {
 229     if (alpha_timezone)
 230         /* use alpha-numeric timezones */
 231         return dasctime (dlocaltime (clock), TW_NULL);
 232
 233     /* use numeric timezones */
 234     return dasctime (dlocaltime (clock), TW_ZONE);
 235 }
 236
 237
 238 /*
 239  * Using a nmh "broken-down" time structure, produce
 240  * a date/time string of the form
 241  *
 242  *      Mon, 16 Jun 1992 15:30:48 -0700
 243  *
 244  * as specified by RFC 822 and RFC 1123.
 245  */
 246
 247 char *
 248 dasctime (struct tws *tw, int flags)
 249 {
 250     char buffer[80];
 251     static char result[80];
 252     int twf;
 253
 254     if (!tw)
 255         return NULL;
 256
 257     /* Display timezone if known */
 258     if (tw->tw_flags & TW_SZEXP)
 259         snprintf(result, sizeof(result), " %s", dtimezone(tw->tw_zone, tw->tw_flags | flags));
 260     else
 261         result[0] = '\0';
 262
 263     snprintf(buffer, sizeof(buffer), "%02d %s %0*d %02d:%02d:%02d%s",
 264             tw->tw_mday, tw_moty[tw->tw_mon],
 265             tw->tw_year < 100 ? 2 : 4, tw->tw_year,
 266             tw->tw_hour, tw->tw_min, tw->tw_sec, result);
 267
 268     if ((twf = tw->tw_flags & TW_SDAY)) {
 269         if (twf == TW_SEXP)
 270             snprintf(result, sizeof(result), "%s, %s", tw_dotw[tw->tw_wday], buffer);
 271         else
 272             snprintf(result, sizeof(result), "%s (%s)", buffer, tw_dotw[tw->tw_wday]);
 273     } else
 274         strncpy(result, buffer, sizeof(result));
 275
 276     return result;
 277 }
 278
 279
 280 /*
 281  * Get the timezone for given offset.
 282  * This used to return a three-letter abbreviation for some offset
 283  * values.  But not many.  Until there's a good way to do that,
 284  * return the string representation of the numeric offset.
 285  */
 286
 287 char *
 288 dtimezone (int offset, int flags)
 289 {
 290     int hours, mins;
 291     static char buffer[10];
 292
 293     if (offset < 0) {
 294         mins = -((-offset) % 60);
 295         hours = -((-offset) / 60);
 296     } else {
 297         mins = offset % 60;
 298         hours = offset / 60;
 299     }
 300
 301     if (flags & TW_DST)
 302         hours++;
 303     snprintf (buffer, sizeof(buffer), "%s%02d%02d",
 304                 offset < 0 ? "-" : "+", abs (hours), abs (mins));
 305     return buffer;
 306 }
 307
 308
 309 /*
 310  * Convert nmh time structure for local "broken-down"
 311  * time to calendar time (clock value).  This routine
 312  * is based on the gtime() routine written by Steven Shafer
 313  * at CMU.  It was forwarded to MTR by Jay Lepreau at Utah-CS.
 314  */
 315
 316 time_t
 317 dmktime (struct tws *tw)
 318 {
 319     int i, sec, min, hour, mday, mon, year;
 320     time_t result;
 321
 322     if (tw->tw_clock != 0)
 323         return tw->tw_clock;
 324
 325     if ((sec = tw->tw_sec) < 0 || sec > 61
 326             || (min = tw->tw_min) < 0 || min > 59
 327             || (hour = tw->tw_hour) < 0 || hour > 23
 328             || (mday = tw->tw_mday) < 1 || mday > 31
 329             || (mon = tw->tw_mon + 1) < 1 || mon > 12)
 330         return (tw->tw_clock = (time_t) -1);
 331
 332     year = tw->tw_year;
 333
 334     result = 0;
 335     if (year < 1970)
 336       year += 1900;
 337
 338     if (year < 1970)
 339       year += 100;
 340
 341     for (i = 1970; i < year; i++)
 342         result += dysize (i);
 343     if (dysize (year) == 366 && mon >= 3)
 344         result++;
 345     while (--mon)
 346         result += dmsize[mon - 1];
 347     result += mday - 1;
 348     result = 24 * result + hour;
 349     result = 60 * result + min;
 350     result = 60 * result + sec;
 351     result -= 60 * tw->tw_zone;
 352     if (tw->tw_flags & TW_DST)
 353         result -= 60 * 60;
 354
 355     return (tw->tw_clock = result);
 356 }
 357
 358
 359 /*
 360  * Simple calculation of day of the week.  Algorithm
 361  * used is Zeller's congruence.  We assume that
 362  * if tw->tw_year < 100, then the century = 19.
 363  */
 364
 365 void
 366 set_dotw (struct tws *tw)
 367 {
 368     int month, day, year, century;
 369
 370     month = tw->tw_mon - 1;
 371     day = tw->tw_mday;
 372     year = tw->tw_year % 100;
 373     century = tw->tw_year < 100 ? 19 : tw->tw_year / 100;
 374
 375     if (month <= 0) {
 376         month += 12;
 377         if (--year < 0) {
 378             year += 100;
 379             century--;
 380         }
 381     }
 382
 383     tw->tw_wday =
 384         ((26 * month - 2) / 10 + day + year + year / 4
 385             - 3 * century / 4 + 1) % 7;
 386     if (tw->tw_wday < 0)
 387         tw->tw_wday += 7;
 388
 389     tw->tw_flags &= ~TW_SDAY;
 390     tw->tw_flags |= TW_SIMP;
 391 }
 392
 393
 394 /*
 395  * Compare two nmh time structures
 396  */
 397
 398 int
 399 twsort (struct tws *tw1, struct tws *tw2)
 400 {
 401     time_t c1, c2;
 402
 403     if (tw1->tw_clock == 0)
 404         dmktime (tw1);
 405     if (tw2->tw_clock == 0)
 406         dmktime (tw2);
 407
 408     return ((c1 = tw1->tw_clock) > (c2 = tw2->tw_clock) ? 1
 409             : c1 == c2 ? 0 : -1);
 410 }