contrib/tzcode/zic/zdump.c

   1 /*
   2 ** This file is in the public domain, so clarified as of
   3 ** 2009-05-17 by Arthur David Olson.
   4 */
   5
   6 #ifndef lint
   7 static const char rcsid[] =
   8   "$FreeBSD$";
   9 static char     elsieid[] = "@(#)zdump.c        8.10";
  10 #endif /* not lint */
  11
  12 /*
  13 ** This code has been made independent of the rest of the time
  14 ** conversion package to increase confidence in the verification it provides.
  15 ** You can use this code to help in verifying other implementations.
  16 */
  17
  18 #include <err.h>
  19 #include <stdio.h>      /* for stdout, stderr */
  20 #include <stdlib.h>     /* for exit, malloc, atoi */
  21 #include <string.h>     /* for strcpy */
  22 #include <sys/types.h>  /* for time_t */
  23 #include <time.h>       /* for struct tm */
  24 #include <unistd.h>
  25 #include <float.h>      /* for FLT_MAX and DBL_MAX */
  26 #include <ctype.h>      /* for isalpha et al. */
  27 #ifndef isascii
  28 #define isascii(x) 1
  29 #endif /* !defined isascii */
  30
  31 #ifndef ZDUMP_LO_YEAR
  32 #define ZDUMP_LO_YEAR   (-500)
  33 #endif /* !defined ZDUMP_LO_YEAR */
  34
  35 #ifndef ZDUMP_HI_YEAR
  36 #define ZDUMP_HI_YEAR   2500
  37 #endif /* !defined ZDUMP_HI_YEAR */
  38
  39 #ifndef MAX_STRING_LENGTH
  40 #define MAX_STRING_LENGTH       1024
  41 #endif /* !defined MAX_STRING_LENGTH */
  42
  43 #ifndef TRUE
  44 #define TRUE            1
  45 #endif /* !defined TRUE */
  46
  47 #ifndef FALSE
  48 #define FALSE           0
  49 #endif /* !defined FALSE */
  50
  51 #ifndef EXIT_SUCCESS
  52 #define EXIT_SUCCESS    0
  53 #endif /* !defined EXIT_SUCCESS */
  54
  55 #ifndef EXIT_FAILURE
  56 #define EXIT_FAILURE    1
  57 #endif /* !defined EXIT_FAILURE */
  58
  59 #ifndef SECSPERMIN
  60 #define SECSPERMIN      60
  61 #endif /* !defined SECSPERMIN */
  62
  63 #ifndef MINSPERHOUR
  64 #define MINSPERHOUR     60
  65 #endif /* !defined MINSPERHOUR */
  66
  67 #ifndef SECSPERHOUR
  68 #define SECSPERHOUR     (SECSPERMIN * MINSPERHOUR)
  69 #endif /* !defined SECSPERHOUR */
  70
  71 #ifndef HOURSPERDAY
  72 #define HOURSPERDAY     24
  73 #endif /* !defined HOURSPERDAY */
  74
  75 #ifndef EPOCH_YEAR
  76 #define EPOCH_YEAR      1970
  77 #endif /* !defined EPOCH_YEAR */
  78
  79 #ifndef TM_YEAR_BASE
  80 #define TM_YEAR_BASE    1900
  81 #endif /* !defined TM_YEAR_BASE */
  82
  83 #ifndef DAYSPERNYEAR
  84 #define DAYSPERNYEAR    365
  85 #endif /* !defined DAYSPERNYEAR */
  86
  87 #ifndef isleap
  88 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
  89 #endif /* !defined isleap */
  90
  91 #ifndef isleap_sum
  92 /*
  93 ** See tzfile.h for details on isleap_sum.
  94 */
  95 #define isleap_sum(a, b)        isleap((a) % 400 + (b) % 400)
  96 #endif /* !defined isleap_sum */
  97
  98 #define SECSPERDAY      ((long) SECSPERHOUR * HOURSPERDAY)
  99 #define SECSPERNYEAR    (SECSPERDAY * DAYSPERNYEAR)
 100 #define SECSPERLYEAR    (SECSPERNYEAR + SECSPERDAY)
 101
 102 #ifndef HAVE_GETTEXT
 103 #define HAVE_GETTEXT 0
 104 #endif
 105 #if HAVE_GETTEXT
 106 #include "locale.h"     /* for setlocale */
 107 #include "libintl.h"
 108 #endif /* HAVE_GETTEXT */
 109
 110 #ifndef GNUC_or_lint
 111 #ifdef lint
 112 #define GNUC_or_lint
 113 #else /* !defined lint */
 114 #ifdef __GNUC__
 115 #define GNUC_or_lint
 116 #endif /* defined __GNUC__ */
 117 #endif /* !defined lint */
 118 #endif /* !defined GNUC_or_lint */
 119
 120 #ifndef INITIALIZE
 121 #ifdef GNUC_or_lint
 122 #define INITIALIZE(x)   ((x) = 0)
 123 #else /* !defined GNUC_or_lint */
 124 #define INITIALIZE(x)
 125 #endif /* !defined GNUC_or_lint */
 126 #endif /* !defined INITIALIZE */
 127
 128 /*
 129 ** For the benefit of GNU folk...
 130 ** `_(MSGID)' uses the current locale's message library string for MSGID.
 131 ** The default is to use gettext if available, and use MSGID otherwise.
 132 */
 133
 134 #ifndef _
 135 #if HAVE_GETTEXT
 136 #define _(msgid) gettext(msgid)
 137 #else /* !(HAVE_GETTEXT) */
 138 #define _(msgid) msgid
 139 #endif /* !(HAVE_GETTEXT) */
 140 #endif /* !defined _ */
 141
 142 #ifndef TZ_DOMAIN
 143 #define TZ_DOMAIN "tz"
 144 #endif /* !defined TZ_DOMAIN */
 145
 146 extern char **  environ;
 147 extern char *   tzname[2];
 148
 149 static time_t   absolute_min_time;
 150 static time_t   absolute_max_time;
 151 static size_t   longest;
 152 static char *   progname;
 153 static int      warned;
 154
 155 static void     usage(FILE *stream, int status);
 156 static char *   abbr(struct tm * tmp);
 157 static void     abbrok(const char * abbrp, const char * zone);
 158 static long     delta(struct tm * newp, struct tm * oldp);
 159 static void     dumptime(const struct tm * tmp);
 160 static time_t   hunt(char * name, time_t lot, time_t    hit);
 161 static void     setabsolutes(void);
 162 static void     show(char * zone, time_t t, int v);
 163 static const char *     tformat(void);
 164 static time_t   yeartot(long y);
 165
 166 #ifndef TYPECHECK
 167 #define my_localtime    localtime
 168 #else /* !defined TYPECHECK */
 169 static struct tm *
 170 my_localtime(tp)
 171 time_t *        tp;
 172 {
 173         register struct tm *    tmp;
 174
 175         tmp = localtime(tp);
 176         if (tp != NULL && tmp != NULL) {
 177                 struct tm       tm;
 178                 register time_t t;
 179
 180                 tm = *tmp;
 181                 t = mktime(&tm);
 182                 if (t - *tp >= 1 || *tp - t >= 1) {
 183                         (void) fflush(stdout);
 184                         (void) fprintf(stderr, "\n%s: ", progname);
 185                         (void) fprintf(stderr, tformat(), *tp);
 186                         (void) fprintf(stderr, " ->");
 187                         (void) fprintf(stderr, " year=%d", tmp->tm_year);
 188                         (void) fprintf(stderr, " mon=%d", tmp->tm_mon);
 189                         (void) fprintf(stderr, " mday=%d", tmp->tm_mday);
 190                         (void) fprintf(stderr, " hour=%d", tmp->tm_hour);
 191                         (void) fprintf(stderr, " min=%d", tmp->tm_min);
 192                         (void) fprintf(stderr, " sec=%d", tmp->tm_sec);
 193                         (void) fprintf(stderr, " isdst=%d", tmp->tm_isdst);
 194                         (void) fprintf(stderr, " -> ");
 195                         (void) fprintf(stderr, tformat(), t);
 196                         (void) fprintf(stderr, "\n");
 197                 }
 198         }
 199         return tmp;
 200 }
 201 #endif /* !defined TYPECHECK */
 202
 203 static void
 204 abbrok(abbrp, zone)
 205 const char * const      abbrp;
 206 const char * const      zone;
 207 {
 208         register const char *   cp;
 209         register char *         wp;
 210
 211         if (warned)
 212                 return;
 213         cp = abbrp;
 214         wp = NULL;
 215         while (isascii((unsigned char) *cp) && isalpha((unsigned char) *cp))
 216                 ++cp;
 217         if (cp - abbrp == 0)
 218                 wp = _("lacks alphabetic at start");
 219         else if (cp - abbrp < 3)
 220                 wp = _("has fewer than 3 alphabetics");
 221         else if (cp - abbrp > 6)
 222                 wp = _("has more than 6 alphabetics");
 223         if (wp == NULL && (*cp == '+' || *cp == '-')) {
 224                 ++cp;
 225                 if (isascii((unsigned char) *cp) &&
 226                         isdigit((unsigned char) *cp))
 227                                 if (*cp++ == '1' && *cp >= '0' && *cp <= '4')
 228                                         ++cp;
 229                 if (*cp != '\0')
 230                         wp = _("differs from POSIX standard");
 231         }
 232         if (wp == NULL)
 233                 return;
 234         (void) fflush(stdout);
 235         (void) fprintf(stderr,
 236                 _("%s: warning: zone \"%s\" abbreviation \"%s\" %s\n"),
 237                 progname, zone, abbrp, wp);
 238         warned = TRUE;
 239 }
 240
 241 int
 242 main(argc, argv)
 243 int     argc;
 244 char *  argv[];
 245 {
 246         register int            i;
 247         register int            c;
 248         register int            vflag;
 249         register char *         cutarg;
 250         register long           cutloyear = ZDUMP_LO_YEAR;
 251         register long           cuthiyear = ZDUMP_HI_YEAR;
 252         register time_t         cutlotime;
 253         register time_t         cuthitime;
 254         register char **        fakeenv;
 255         time_t                  now;
 256         time_t                  t;
 257         time_t                  newt;
 258         struct tm               tm;
 259         struct tm               newtm;
 260         register struct tm *    tmp;
 261         register struct tm *    newtmp;
 262
 263         INITIALIZE(cutlotime);
 264         INITIALIZE(cuthitime);
 265 #if HAVE_GETTEXT
 266         (void) setlocale(LC_MESSAGES, "");
 267 #ifdef TZ_DOMAINDIR
 268         (void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
 269 #endif /* TEXTDOMAINDIR */
 270         (void) textdomain(TZ_DOMAIN);
 271 #endif /* HAVE_GETTEXT */
 272         for (i = 1; i < argc; ++i)
 273                 if (strcmp(argv[i], "--version") == 0) {
 274                         errx(EXIT_SUCCESS, "%s", elsieid);
 275                 } else if (strcmp(argv[i], "--help") == 0) {
 276                         usage(stdout, EXIT_SUCCESS);
 277                 }
 278         vflag = 0;
 279         cutarg = NULL;
 280         while ((c = getopt(argc, argv, "c:v")) == 'c' || c == 'v')
 281                 if (c == 'v')
 282                         vflag = 1;
 283                 else    cutarg = optarg;
 284         if ((c != -1) ||
 285                 (optind == argc - 1 && strcmp(argv[optind], "=") == 0)) {
 286                         usage(stderr, EXIT_FAILURE);
 287         }
 288         if (vflag) {
 289                 if (cutarg != NULL) {
 290                         long    lo;
 291                         long    hi;
 292                         char    dummy;
 293
 294                         if (sscanf(cutarg, "%ld%c", &hi, &dummy) == 1) {
 295                                 cuthiyear = hi;
 296                         } else if (sscanf(cutarg, "%ld,%ld%c",
 297                                 &lo, &hi, &dummy) == 2) {
 298                                         cutloyear = lo;
 299                                         cuthiyear = hi;
 300                         } else {
 301 (void) fprintf(stderr, _("%s: wild -c argument %s\n"),
 302                                         progname, cutarg);
 303                                 exit(EXIT_FAILURE);
 304                         }
 305                 }
 306                 setabsolutes();
 307                 cutlotime = yeartot(cutloyear);
 308                 cuthitime = yeartot(cuthiyear);
 309         }
 310         (void) time(&now);
 311         longest = 0;
 312         for (i = optind; i < argc; ++i)
 313                 if (strlen(argv[i]) > longest)
 314                         longest = strlen(argv[i]);
 315         {
 316                 register int    from;
 317                 register int    to;
 318
 319                 for (i = 0;  environ[i] != NULL; ++i)
 320                         continue;
 321                 fakeenv = (char **) malloc((size_t) ((i + 2) *
 322                         sizeof *fakeenv));
 323                 if (fakeenv == NULL ||
 324                         (fakeenv[0] = (char *) malloc((size_t) (longest +
 325                                 4))) == NULL)
 326                                         errx(EXIT_FAILURE,
 327                                              _("malloc() failed"));
 328                 to = 0;
 329                 (void) strcpy(fakeenv[to++], "TZ=");
 330                 for (from = 0; environ[from] != NULL; ++from)
 331                         if (strncmp(environ[from], "TZ=", 3) != 0)
 332                                 fakeenv[to++] = environ[from];
 333                 fakeenv[to] = NULL;
 334                 environ = fakeenv;
 335         }
 336         for (i = optind; i < argc; ++i) {
 337                 static char     buf[MAX_STRING_LENGTH];
 338
 339                 (void) strcpy(&fakeenv[0][3], argv[i]);
 340                 if (!vflag) {
 341                         show(argv[i], now, FALSE);
 342                         continue;
 343                 }
 344                 warned = FALSE;
 345                 t = absolute_min_time;
 346                 show(argv[i], t, TRUE);
 347                 t += SECSPERHOUR * HOURSPERDAY;
 348                 show(argv[i], t, TRUE);
 349                 if (t < cutlotime)
 350                         t = cutlotime;
 351                 tmp = my_localtime(&t);
 352                 if (tmp != NULL) {
 353                         tm = *tmp;
 354                         (void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
 355                 }
 356                 for ( ; ; ) {
 357                         if (t >= cuthitime || t >= cuthitime - SECSPERHOUR * 12)
 358                                 break;
 359                         newt = t + SECSPERHOUR * 12;
 360                         newtmp = localtime(&newt);
 361                         if (newtmp != NULL)
 362                                 newtm = *newtmp;
 363                         if ((tmp == NULL || newtmp == NULL) ? (tmp != newtmp) :
 364                                 (delta(&newtm, &tm) != (newt - t) ||
 365                                 newtm.tm_isdst != tm.tm_isdst ||
 366                                 strcmp(abbr(&newtm), buf) != 0)) {
 367                                         newt = hunt(argv[i], t, newt);
 368                                         newtmp = localtime(&newt);
 369                                         if (newtmp != NULL) {
 370                                                 newtm = *newtmp;
 371                                                 (void) strncpy(buf,
 372                                                         abbr(&newtm),
 373                                                         (sizeof buf) - 1);
 374                                         }
 375                         }
 376                         t = newt;
 377                         tm = newtm;
 378                         tmp = newtmp;
 379                 }
 380                 t = absolute_max_time;
 381                 t -= SECSPERHOUR * HOURSPERDAY;
 382                 show(argv[i], t, TRUE);
 383                 t += SECSPERHOUR * HOURSPERDAY;
 384                 show(argv[i], t, TRUE);
 385         }
 386         if (fflush(stdout) || ferror(stdout))
 387                 errx(EXIT_FAILURE, _("error writing standard output"));
 388         exit(EXIT_SUCCESS);
 389         /* If exit fails to exit... */
 390         return(EXIT_FAILURE);
 391 }
 392
 393 static void
 394 setabsolutes(void)
 395 {
 396         if (0.5 == (time_t) 0.5) {
 397                 /*
 398                 ** time_t is floating.
 399                 */
 400                 if (sizeof (time_t) == sizeof (float)) {
 401                         absolute_min_time = (time_t) -FLT_MAX;
 402                         absolute_max_time = (time_t) FLT_MAX;
 403                 } else if (sizeof (time_t) == sizeof (double)) {
 404                         absolute_min_time = (time_t) -DBL_MAX;
 405                         absolute_max_time = (time_t) DBL_MAX;
 406                 } else {
 407                         (void) fprintf(stderr,
 408 _("%s: use of -v on system with floating time_t other than float or double\n"),
 409                                 progname);
 410                         exit(EXIT_FAILURE);
 411                 }
 412         } else if (0 > (time_t) -1) {
 413                 /*
 414                 ** time_t is signed.  Assume overflow wraps around.
 415                 */
 416                 time_t t = 0;
 417                 time_t t1 = 1;
 418
 419                 while (t < t1) {
 420                         t = t1;
 421                         t1 = 2 * t1 + 1;
 422                 }
 423
 424                 absolute_max_time = t;
 425                 t = -t;
 426                 absolute_min_time = t - 1;
 427                 if (t < absolute_min_time)
 428                         absolute_min_time = t;
 429         } else {
 430                 /*
 431                 ** time_t is unsigned.
 432                 */
 433                 absolute_min_time = 0;
 434                 absolute_max_time = absolute_min_time - 1;
 435         }
 436 }
 437
 438 static time_t
 439 yeartot(y)
 440 const long      y;
 441 {
 442         register long   myy;
 443         register long   seconds;
 444         register time_t t;
 445
 446         myy = EPOCH_YEAR;
 447         t = 0;
 448         while (myy != y) {
 449                 if (myy < y) {
 450                         seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
 451                         ++myy;
 452                         if (t > absolute_max_time - seconds) {
 453                                 t = absolute_max_time;
 454                                 break;
 455                         }
 456                         t += seconds;
 457                 } else {
 458                         --myy;
 459                         seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
 460                         if (t < absolute_min_time + seconds) {
 461                                 t = absolute_min_time;
 462                                 break;
 463                         }
 464                         t -= seconds;
 465                 }
 466         }
 467         return t;
 468 }
 469
 470 static void
 471 usage(FILE *stream, int status)
 472 {
 473         fprintf(stream,
 474 _("usage: %s [--version] [-v] [--help] [-c [loyear,]hiyear] zonename ...\n\
 475 \n\
 476 Report bugs to tz@elsie.nci.nih.gov.\n"), progname);
 477         exit(status);
 478 }
 479
 480 static time_t
 481 hunt(char *name, time_t lot, time_t hit)
 482 {
 483         time_t                  t;
 484         long                    diff;
 485         struct tm               lotm;
 486         register struct tm *    lotmp;
 487         struct tm               tm;
 488         register struct tm *    tmp;
 489         char                    loab[MAX_STRING_LENGTH];
 490
 491         lotmp = my_localtime(&lot);
 492         if (lotmp != NULL) {
 493                 lotm = *lotmp;
 494                 (void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
 495         }
 496         for ( ; ; ) {
 497                 diff = (long) (hit - lot);
 498                 if (diff < 2)
 499                         break;
 500                 t = lot;
 501                 t += diff / 2;
 502                 if (t <= lot)
 503                         ++t;
 504                 else if (t >= hit)
 505                         --t;
 506                 tmp = my_localtime(&t);
 507                 if (tmp != NULL)
 508                         tm = *tmp;
 509                 if ((lotmp == NULL || tmp == NULL) ? (lotmp == tmp) :
 510                         (delta(&tm, &lotm) == (t - lot) &&
 511                         tm.tm_isdst == lotm.tm_isdst &&
 512                         strcmp(abbr(&tm), loab) == 0)) {
 513                                 lot = t;
 514                                 lotm = tm;
 515                                 lotmp = tmp;
 516                 } else  hit = t;
 517         }
 518         show(name, lot, TRUE);
 519         show(name, hit, TRUE);
 520         return hit;
 521 }
 522
 523 /*
 524 ** Thanks to Paul Eggert for logic used in delta.
 525 */
 526
 527 static long
 528 delta(newp, oldp)
 529 struct tm *     newp;
 530 struct tm *     oldp;
 531 {
 532         register long   result;
 533         register int    tmy;
 534
 535         if (newp->tm_year < oldp->tm_year)
 536                 return -delta(oldp, newp);
 537         result = 0;
 538         for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
 539                 result += DAYSPERNYEAR + isleap_sum(tmy, TM_YEAR_BASE);
 540         result += newp->tm_yday - oldp->tm_yday;
 541         result *= HOURSPERDAY;
 542         result += newp->tm_hour - oldp->tm_hour;
 543         result *= MINSPERHOUR;
 544         result += newp->tm_min - oldp->tm_min;
 545         result *= SECSPERMIN;
 546         result += newp->tm_sec - oldp->tm_sec;
 547         return result;
 548 }
 549
 550 static void
 551 show(char *zone, time_t t, int v)
 552 {
 553         register struct tm *    tmp;
 554
 555         (void) printf("%-*s  ", (int) longest, zone);
 556         if (v) {
 557                 tmp = gmtime(&t);
 558                 if (tmp == NULL) {
 559                         (void) printf(tformat(), t);
 560                 } else {
 561                         dumptime(tmp);
 562                         (void) printf(" UTC");
 563                 }
 564                 (void) printf(" = ");
 565         }
 566         tmp = my_localtime(&t);
 567         dumptime(tmp);
 568         if (tmp != NULL) {
 569                 if (*abbr(tmp) != '\0')
 570                         (void) printf(" %s", abbr(tmp));
 571                 if (v) {
 572                         (void) printf(" isdst=%d", tmp->tm_isdst);
 573 #ifdef TM_GMTOFF
 574                         (void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
 575 #endif /* defined TM_GMTOFF */
 576                 }
 577         }
 578         (void) printf("\n");
 579         if (tmp != NULL && *abbr(tmp) != '\0')
 580                 abbrok(abbr(tmp), zone);
 581 }
 582
 583 static char *
 584 abbr(tmp)
 585 struct tm *     tmp;
 586 {
 587         register char * result;
 588         static char     nada;
 589
 590         if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
 591                 return &nada;
 592         result = tzname[tmp->tm_isdst];
 593         return (result == NULL) ? &nada : result;
 594 }
 595
 596 /*
 597 ** The code below can fail on certain theoretical systems;
 598 ** it works on all known real-world systems as of 2004-12-30.
 599 */
 600
 601 static const char *
 602 tformat(void)
 603 {
 604         if (0.5 == (time_t) 0.5) {      /* floating */
 605                 if (sizeof (time_t) > sizeof (double))
 606                         return "%Lg";
 607                 return "%g";
 608         }
 609         if (0 > (time_t) -1) {          /* signed */
 610                 if (sizeof (time_t) > sizeof (long))
 611                         return "%lld";
 612                 if (sizeof (time_t) > sizeof (int))
 613                         return "%ld";
 614                 return "%d";
 615         }
 616         if (sizeof (time_t) > sizeof (unsigned long))
 617                 return "%llu";
 618         if (sizeof (time_t) > sizeof (unsigned int))
 619                 return "%lu";
 620         return "%u";
 621 }
 622
 623 static void
 624 dumptime(timeptr)
 625 register const struct tm *      timeptr;
 626 {
 627         static const char       wday_name[][3] = {
 628                 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
 629         };
 630         static const char       mon_name[][3] = {
 631                 "Jan", "Feb", "Mar", "Apr", "May", "Jun",
 632                 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
 633         };
 634         register const char *   wn;
 635         register const char *   mn;
 636         register int            lead;
 637         register int            trail;
 638
 639         if (timeptr == NULL) {
 640                 (void) printf("NULL");
 641                 return;
 642         }
 643         /*
 644         ** The packaged versions of localtime and gmtime never put out-of-range
 645         ** values in tm_wday or tm_mon, but since this code might be compiled
 646         ** with other (perhaps experimental) versions, paranoia is in order.
 647         */
 648         if (timeptr->tm_wday < 0 || timeptr->tm_wday >=
 649                 (int) (sizeof wday_name / sizeof wday_name[0]))
 650                         wn = "???";
 651         else            wn = wday_name[timeptr->tm_wday];
 652         if (timeptr->tm_mon < 0 || timeptr->tm_mon >=
 653                 (int) (sizeof mon_name / sizeof mon_name[0]))
 654                         mn = "???";
 655         else            mn = mon_name[timeptr->tm_mon];
 656         (void) printf("%.3s %.3s%3d %.2d:%.2d:%.2d ",
 657                 wn, mn,
 658                 timeptr->tm_mday, timeptr->tm_hour,
 659                 timeptr->tm_min, timeptr->tm_sec);
 660 #define DIVISOR 10
 661         trail = timeptr->tm_year % DIVISOR + TM_YEAR_BASE % DIVISOR;
 662         lead = timeptr->tm_year / DIVISOR + TM_YEAR_BASE / DIVISOR +
 663                 trail / DIVISOR;
 664         trail %= DIVISOR;
 665         if (trail < 0 && lead > 0) {
 666                 trail += DIVISOR;
 667                 --lead;
 668         } else if (lead < 0 && trail > 0) {
 669                 trail -= DIVISOR;
 670                 ++lead;
 671         }
 672         if (lead == 0)
 673                 (void) printf("%d", trail);
 674         else    (void) printf("%d%d", lead, ((trail < 0) ? -trail : trail));
 675 }