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"
   9 #include "dtime.h"
  10 #include "h/nmh.h"
  11 #include "h/utils.h"
  12 #include "h/tws.h"
  13 #include <time.h>
  14
  15 #if !defined(HAVE_STRUCT_TM_TM_GMTOFF)
  16 extern long timezone;
  17 #endif
  18
  19 /* Size of largest possible int representing a time zone offset in minutes:
  20    2,147,483,648 / 60 = 35,791,394 */
  21 #define DTZ_BUFFER_SIZE (sizeof "+3579139459")
  22
  23 /*
  24  * 1 if leap year, 0 otherwise.
  25  */
  26 #define isleapyear01(y) \
  27         (((y) % 4) ? 0 : (((y) % 100) ? 1 : (((y) % 400) ? 0 : 1)))
  28
  29 /*
  30  * The number of days in the year, accounting for leap years
  31  */
  32 #define dysize(y)       \
  33         (365 + isleapyear01(y))
  34
  35 char *tw_moty[] = {
  36     "Jan", "Feb", "Mar", "Apr",
  37     "May", "Jun", "Jul", "Aug",
  38     "Sep", "Oct", "Nov", "Dec",
  39     NULL
  40 };
  41
  42 char *tw_dotw[] = {
  43     "Sun", "Mon", "Tue",
  44     "Wed", "Thu", "Fri",
  45     "Sat", NULL
  46 };
  47
  48 char *tw_ldotw[] = {
  49     "Sunday",    "Monday",   "Tuesday",
  50     "Wednesday", "Thursday", "Friday",
  51     "Saturday",  NULL
  52 };
  53
  54 static int dmsize[][12] = {
  55     { /* Not a leap year */
  56         31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
  57     },
  58     { /* Leap year: February = 29 */
  59         31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
  60     }
  61 };
  62
  63
  64 /*
  65  * Get current time (adjusted for local time
  66  * zone and daylight savings time) expressed
  67  * as nmh "broken-down" time structure.
  68  */
  69
  70 struct tws *
  71 dlocaltimenow (void)
  72 {
  73     time_t clock;
  74
  75     time (&clock);
  76     return dlocaltime (&clock);
  77 }
  78
  79
  80 /*
  81  * Take clock value and return pointer to nmh time structure
  82  * containing "broken-down" time.  The time is adjusted for
  83  * local time zone and daylight savings time.
  84  */
  85
  86 struct tws *
  87 dlocaltime (time_t *clock)
  88 {
  89     static struct tws tw;
  90     struct tm *tm;
  91
  92     if (!clock)
  93         return NULL;
  94
  95     tm = localtime (clock);
  96
  97     tw.tw_sec  = tm->tm_sec;
  98     tw.tw_min  = tm->tm_min;
  99     tw.tw_hour = tm->tm_hour;
 100     tw.tw_mday = tm->tm_mday;
 101     tw.tw_mon  = tm->tm_mon;
 102
 103     /*
 104      * tm_year is always "year - 1900".
 105      * So we correct for this.
 106      */
 107     tw.tw_year = tm->tm_year + 1900;
 108     tw.tw_wday = tm->tm_wday;
 109     tw.tw_yday = tm->tm_yday;
 110
 111     tw.tw_flags = TW_NULL;
 112     if (tm->tm_isdst)
 113         tw.tw_flags |= TW_DST;
 114
 115 #ifdef HAVE_STRUCT_TM_TM_GMTOFF
 116     tw.tw_zone = tm->tm_gmtoff / 60;
 117     if (tm->tm_isdst)                   /* if DST is in effect */
 118         tw.tw_zone -= 60;               /* reset to normal offset */
 119 #else
 120     {
 121         static bool deja_vu;
 122
 123         if (!deja_vu) {
 124             deja_vu = true;
 125             tzset();
 126         }
 127     }
 128     tw.tw_zone = -(timezone / 60);
 129 #endif
 130
 131     tw.tw_flags &= ~TW_SDAY;
 132     tw.tw_flags |= TW_SEXP;
 133     tw.tw_flags |= TW_SZEXP;
 134
 135     tw.tw_clock = *clock;
 136
 137     return &tw;
 138 }
 139
 140
 141 /*
 142  * Take clock value and return pointer to nmh time
 143  * structure containing "broken-down" time.  Time is
 144  * expressed in UTC (Coordinated Universal Time).
 145  */
 146
 147 struct tws *
 148 dgmtime (time_t *clock)
 149 {
 150     static struct tws tw;
 151     struct tm *tm;
 152
 153     if (!clock)
 154         return NULL;
 155
 156     tm = gmtime (clock);
 157
 158     tw.tw_sec  = tm->tm_sec;
 159     tw.tw_min  = tm->tm_min;
 160     tw.tw_hour = tm->tm_hour;
 161     tw.tw_mday = tm->tm_mday;
 162     tw.tw_mon  = tm->tm_mon;
 163
 164     /*
 165      * tm_year is always "year - 1900"
 166      * So we correct for this.
 167      */
 168     tw.tw_year = tm->tm_year + 1900;
 169     tw.tw_wday = tm->tm_wday;
 170     tw.tw_yday = tm->tm_yday;
 171
 172     tw.tw_flags = TW_NULL;
 173     if (tm->tm_isdst)
 174         tw.tw_flags |= TW_DST;
 175
 176     tw.tw_zone = 0;
 177
 178     tw.tw_flags &= ~TW_SDAY;
 179     tw.tw_flags |= TW_SEXP;
 180     tw.tw_flags |= TW_SZEXP;
 181
 182     tw.tw_clock = *clock;
 183
 184     return &tw;
 185 }
 186
 187
 188 /*
 189  * Using a nmh "broken-down" time structure,
 190  * produce a 26-byte date/time string, such as
 191  *
 192  *      Tue Jan 14 17:49:03 1992\n\0
 193  */
 194
 195 char *
 196 dctime (struct tws *tw)
 197 {
 198     static char buffer[26];
 199
 200     if (!tw)
 201         return NULL;
 202
 203     snprintf (buffer, sizeof(buffer), "%.3s %.3s %02d %02d:%02d:%02d %s\n",
 204             tw_dotw[tw->tw_wday], tw_moty[tw->tw_mon], tw->tw_mday,
 205             tw->tw_hour, tw->tw_min, tw->tw_sec,
 206             m_strn(tw->tw_year < 100 ? tw->tw_year + 1900 : tw->tw_year, 4));
 207
 208     return buffer;
 209 }
 210
 211
 212 /*
 213  * Produce a date/time string of the form
 214  *
 215  *      Mon, 16 Jun 1992 15:30:48 -700 (or)
 216  *      Mon, 16 Jun 1992 15:30:48 EDT
 217  *
 218  * for the current time, as specified by RFC 822.
 219  * The first form is required by RFC 1123.
 220  */
 221
 222 char *
 223 dtimenow (int alpha_timezone)
 224 {
 225     time_t clock;
 226
 227     time (&clock);
 228     return dtime (&clock, alpha_timezone);
 229 }
 230
 231
 232 /*
 233  * Using a local calendar time value, produce
 234  * a date/time string of the form
 235  *
 236  *      Mon, 16 Jun 1992 15:30:48 -700  (or)
 237  *      Mon, 16 Jun 1992 15:30:48 EDT
 238  *
 239  * as specified by RFC 822.  The first form is required
 240  * by RFC 1123 for outgoing messages.
 241  */
 242
 243 char *
 244 dtime (time_t *clock, int alpha_timezone)
 245 {
 246     if (alpha_timezone)
 247         /* use alpha-numeric timezones */
 248         return dasctime (dlocaltime (clock), TW_NULL);
 249
 250     /* use numeric timezones */
 251     return dasctime (dlocaltime (clock), TW_ZONE);
 252 }
 253
 254
 255 /*
 256  * Using a nmh "broken-down" time structure, produce
 257  * a date/time string of the form
 258  *
 259  *      Mon, 16 Jun 1992 15:30:48 -0700
 260  *
 261  * as specified by RFC 822 and RFC 1123.
 262  */
 263
 264 char *
 265 dasctime (struct tws *tw, int flags)
 266 {
 267     char buffer[77];
 268     char tzbuffer[DTZ_BUFFER_SIZE];
 269     static char result[80];
 270     int twf;
 271
 272     if (!tw)
 273         return NULL;
 274
 275     /* Display timezone if known */
 276     if (tw->tw_flags & TW_SZEXP)
 277         snprintf(tzbuffer, sizeof(tzbuffer), " %s", dtimezone(tw->tw_zone, tw->tw_flags | flags));
 278     else
 279         tzbuffer[0] = '\0';
 280
 281     snprintf(buffer, sizeof(buffer), "%02d %s %0*d %02d:%02d:%02d%s",
 282             tw->tw_mday, tw_moty[tw->tw_mon],
 283             tw->tw_year < 100 ? 2 : 4, tw->tw_year,
 284             tw->tw_hour, tw->tw_min, tw->tw_sec, tzbuffer);
 285
 286     if ((twf = tw->tw_flags & TW_SDAY)) {
 287         if (twf == TW_SEXP)
 288             snprintf(result, sizeof(result), "%s, %s", tw_dotw[tw->tw_wday], buffer);
 289         else
 290             snprintf(result, sizeof(result), "%s (%s)", buffer, tw_dotw[tw->tw_wday]);
 291     } else
 292         strncpy(result, buffer, sizeof(result));
 293
 294     return result;
 295 }
 296
 297
 298 /*
 299  * Get the timezone for given offset.
 300  * This used to return a three-letter abbreviation for some offset
 301  * values.  But not many.  Until there's a good way to do that,
 302  * return the string representation of the numeric offset.
 303  */
 304
 305 char *
 306 dtimezone(int offset, int flags)
 307 {
 308     static char buffer[DTZ_BUFFER_SIZE];
 309     bool pos;
 310     unsigned os, hours, mins;
 311
 312     pos = offset >= 0;
 313     os = pos ? offset : ~offset + 1; /* abs(3) undefined on INT_MIN. */
 314     hours = os / 60;
 315     mins = os % 60;
 316
 317     if (flags & TW_DST) /* Shift towards +infinity. */
 318         hours += pos ? 1 : -1;
 319
 320     snprintf(buffer, sizeof(buffer), "%c%02u%02u",
 321         pos ? '+' : '-', hours, mins);
 322
 323     return buffer;
 324 }
 325
 326
 327 /*
 328  * Last day of month (1-12) in given year.
 329  */
 330
 331 int
 332 dmlastday(int year, int mon)
 333 {
 334     return dmsize[isleapyear01 (year)][mon - 1];
 335 }
 336
 337 /*
 338  * Convert nmh time structure for local "broken-down"
 339  * time to calendar time (clock value).  This routine
 340  * is based on the gtime() routine written by Steven Shafer
 341  * at CMU.  It was forwarded to MTR by Jay Lepreau at Utah-CS.
 342  */
 343
 344 time_t
 345 dmktime (struct tws *tw)
 346 {
 347     int i, sec, min, hour, mday, mon, year, *msize;
 348     time_t result;
 349
 350     if (tw->tw_clock != 0)
 351         return tw->tw_clock;
 352
 353     if ((sec = tw->tw_sec) < 0 || sec > 61
 354             || (min = tw->tw_min) < 0 || min > 59
 355             || (hour = tw->tw_hour) < 0 || hour > 23
 356             || (mday = tw->tw_mday) < 1 || mday > 31
 357             || (mon = tw->tw_mon + 1) < 1 || mon > 12)
 358         return (tw->tw_clock = (time_t) -1);
 359
 360     year = tw->tw_year;
 361
 362     result = 0;
 363     if (year < 1970)
 364       year += 1900;
 365
 366     if (year < 1970)
 367       year += 100;
 368
 369     for (i = 1970; i < year; i++)
 370         result += dysize (i);
 371     msize = dmsize[isleapyear01 (year)];
 372     while (--mon)
 373         result += msize[mon - 1];
 374     result += mday - 1;
 375     result *= 24; /* Days to hours. */
 376     result += hour;
 377     result *= 60; /* Hours to minutes. */
 378     result += min;
 379     result *= 60; /* Minutes to seconds. */
 380     result += sec;
 381     result -= 60 * tw->tw_zone;
 382     if (tw->tw_flags & TW_DST)
 383         result -= 60 * 60; /* One hour. */
 384
 385     return tw->tw_clock = result;
 386 }
 387
 388
 389 /*
 390  * Simple calculation of day of the week.  Algorithm
 391  * used is Zeller's congruence.  We assume that
 392  * if tw->tw_year < 100, then the century = 19.
 393  */
 394
 395 void
 396 set_dotw (struct tws *tw)
 397 {
 398     int month, day, year, century;
 399
 400     month = tw->tw_mon - 1;
 401     day = tw->tw_mday;
 402     year = tw->tw_year % 100;
 403     century = tw->tw_year < 100 ? 19 : tw->tw_year / 100;
 404
 405     if (month <= 0) {
 406         month += 12;
 407         if (--year < 0) {
 408             year += 100;
 409             century--;
 410         }
 411     }
 412
 413     tw->tw_wday =
 414         ((26 * month - 2) / 10 + day + year + year / 4
 415             - 3 * century / 4 + 1) % 7;
 416     if (tw->tw_wday < 0)
 417         tw->tw_wday += 7;
 418
 419     tw->tw_flags &= ~TW_SDAY;
 420     tw->tw_flags |= TW_SIMP;
 421 }
 422
 423
 424 /*
 425  * Compare two nmh time structures
 426  */
 427
 428 int
 429 twsort (struct tws *tw1, struct tws *tw2)
 430 {
 431     time_t c1, c2;
 432
 433     if (tw1->tw_clock == 0)
 434         dmktime (tw1);
 435     if (tw2->tw_clock == 0)
 436         dmktime (tw2);
 437
 438     return (c1 = tw1->tw_clock) > (c2 = tw2->tw_clock) ? 1
 439             : c1 == c2 ? 0 : -1;
 440 }