lib/libc/time/zdump.c

   1 /*      $NetBSD: zdump.c,v 1.25 2012/08/09 12:38:26 christos Exp $      */
   2 /*
   3 ** This file is in the public domain, so clarified as of
   4 ** 2009-05-17 by Arthur David Olson.
   5 */
   6
   7 #include <sys/cdefs.h>
   8 #ifndef lint
   9 __RCSID("$NetBSD: zdump.c,v 1.25 2012/08/09 12:38:26 christos Exp $");
  10 #endif /* !defined lint */
  11
  12 #include "version.h"
  13 /*
  14 ** This code has been made independent of the rest of the time
  15 ** conversion package to increase confidence in the verification it provides.
  16 ** You can use this code to help in verifying other implementations.
  17 */
  18
  19 #include "stdio.h"      /* for stdout, stderr */
  20 #include "string.h"     /* for strcpy */
  21 #include "sys/types.h"  /* for time_t */
  22 #include "time.h"       /* for struct tm */
  23 #include "stdlib.h"     /* for exit, malloc, atoi */
  24 #include <err.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 int      getopt(int argc, char * const argv[],
 148                         const char * options);
 149 extern char *   optarg;
 150 extern int      optind;
 151
 152 static time_t   absolute_min_time;
 153 static time_t   absolute_max_time;
 154 static size_t   longest;
 155 static char *   progname;
 156 static int      warned;
 157
 158 static const char *     abbr(struct tm * tmp);
 159 static void     abbrok(const char * abbrp, const char * zone);
 160 static long     delta(struct tm * newp, struct tm * oldp);
 161 static void     dumptime(const struct tm * tmp);
 162 static time_t   hunt(char * name, time_t lot, time_t    hit);
 163 int             main(int, char **);
 164 static void     setabsolutes(void);
 165 static void     show(char * zone, time_t t, int v);
 166 static const char *     tformat(void);
 167 static time_t   yeartot(long y);
 168
 169 #ifndef TYPECHECK
 170 #define my_localtime    localtime
 171 #else /* !defined TYPECHECK */
 172 static struct tm *
 173 my_localtime(tp)
 174 time_t *        tp;
 175 {
 176         register struct tm *    tmp;
 177
 178         tmp = localtime(tp);
 179         if (tp != NULL && tmp != NULL) {
 180                 struct tm       tm;
 181                 register time_t t;
 182
 183                 tm = *tmp;
 184                 t = mktime(&tm);
 185                 if (t - *tp >= 1 || *tp - t >= 1) {
 186                         (void) fflush(stdout);
 187                         (void) fprintf(stderr, "\n%s: ", progname);
 188                         (void) fprintf(stderr, tformat(), *tp);
 189                         (void) fprintf(stderr, " ->");
 190                         (void) fprintf(stderr, " year=%d", tmp->tm_year);
 191                         (void) fprintf(stderr, " mon=%d", tmp->tm_mon);
 192                         (void) fprintf(stderr, " mday=%d", tmp->tm_mday);
 193                         (void) fprintf(stderr, " hour=%d", tmp->tm_hour);
 194                         (void) fprintf(stderr, " min=%d", tmp->tm_min);
 195                         (void) fprintf(stderr, " sec=%d", tmp->tm_sec);
 196                         (void) fprintf(stderr, " isdst=%d", tmp->tm_isdst);
 197                         (void) fprintf(stderr, " -> ");
 198                         (void) fprintf(stderr, tformat(), t);
 199                         (void) fprintf(stderr, "\n");
 200                 }
 201         }
 202         return tmp;
 203 }
 204 #endif /* !defined TYPECHECK */
 205
 206 static void
 207 abbrok(abbrp, zone)
 208 const char * const      abbrp;
 209 const char * const      zone;
 210 {
 211         register const char *   cp;
 212         register const char *   wp;
 213
 214         if (warned)
 215                 return;
 216         cp = abbrp;
 217         wp = NULL;
 218         while (isascii((unsigned char) *cp) && isalpha((unsigned char) *cp))
 219                 ++cp;
 220         if (cp - abbrp == 0)
 221                 wp = _("lacks alphabetic at start");
 222         else if (cp - abbrp < 3)
 223                 wp = _("has fewer than 3 alphabetics");
 224         else if (cp - abbrp > 6)
 225                 wp = _("has more than 6 alphabetics");
 226         if (wp == NULL && (*cp == '+' || *cp == '-')) {
 227                 ++cp;
 228                 if (isascii((unsigned char) *cp) &&
 229                         isdigit((unsigned char) *cp))
 230                                 if (*cp++ == '1' && *cp >= '0' && *cp <= '4')
 231                                         ++cp;
 232                 if (*cp != '\0')
 233                         wp = _("differs from POSIX standard");
 234         }
 235         if (wp == NULL)
 236                 return;
 237         (void) fflush(stdout);
 238         (void) fprintf(stderr,
 239                 _("%s: warning: zone \"%s\" abbreviation \"%s\" %s\n"),
 240                 progname, zone, abbrp, wp);
 241         warned = TRUE;
 242 }
 243
 244 __dead static void
 245 usage(FILE *stream, int status)
 246 {
 247         (void) fprintf(stream,
 248 _("%s: usage is %s [ --version ] [ --help ] [ -v ] [ -c [loyear,]hiyear ] zonename ...\n\
 249 \n\
 250 Report bugs to tz@elsie.nci.nih.gov.\n"),
 251                        progname, progname);
 252         exit(status);
 253 }
 254
 255 int
 256 main(argc, argv)
 257 int     argc;
 258 char *  argv[];
 259 {
 260         register int            i;
 261         register int            c;
 262         register int            vflag;
 263         register char *         cutarg;
 264         register long           cutloyear = ZDUMP_LO_YEAR;
 265         register long           cuthiyear = ZDUMP_HI_YEAR;
 266         register time_t         cutlotime;
 267         register time_t         cuthitime;
 268         register char **        fakeenv;
 269         time_t                  now;
 270         time_t                  t;
 271         time_t                  newt;
 272         struct tm               tm;
 273         struct tm               newtm;
 274         register struct tm *    tmp;
 275         register struct tm *    newtmp;
 276
 277         INITIALIZE(cutlotime);
 278         INITIALIZE(cuthitime);
 279 #if HAVE_GETTEXT
 280         (void) setlocale(LC_ALL, "");
 281 #ifdef TZ_DOMAINDIR
 282         (void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
 283 #endif /* defined TEXTDOMAINDIR */
 284         (void) textdomain(TZ_DOMAIN);
 285 #endif /* HAVE_GETTEXT */
 286         progname = argv[0];
 287         for (i = 1; i < argc; ++i)
 288                 if (strcmp(argv[i], "--version") == 0) {
 289                         (void) printf("%s\n", TZVERSION);
 290                         exit(EXIT_SUCCESS);
 291                 } else if (strcmp(argv[i], "--help") == 0) {
 292                         usage(stdout, EXIT_SUCCESS);
 293                 }
 294         vflag = 0;
 295         cutarg = NULL;
 296         while ((c = getopt(argc, argv, "c:v")) == 'c' || c == 'v')
 297                 if (c == 'v')
 298                         vflag = 1;
 299                 else    cutarg = optarg;
 300         if ((c != EOF && c != -1) ||
 301                 (optind == argc - 1 && strcmp(argv[optind], "=") == 0)) {
 302                         usage(stderr, EXIT_FAILURE);
 303         }
 304         if (vflag) {
 305                 if (cutarg != NULL) {
 306                         long    lo;
 307                         long    hi;
 308                         char    dummy;
 309
 310                         if (sscanf(cutarg, "%ld%c", &hi, &dummy) == 1) {
 311                                 cuthiyear = hi;
 312                         } else if (sscanf(cutarg, "%ld,%ld%c",
 313                                 &lo, &hi, &dummy) == 2) {
 314                                         cutloyear = lo;
 315                                         cuthiyear = hi;
 316                         } else {
 317 (void) fprintf(stderr, _("%s: wild -c argument %s\n"),
 318                                         progname, cutarg);
 319                                 exit(EXIT_FAILURE);
 320                         }
 321                 }
 322                 setabsolutes();
 323                 cutlotime = yeartot(cutloyear);
 324                 cuthitime = yeartot(cuthiyear);
 325         }
 326         (void) time(&now);
 327         longest = 0;
 328         for (i = optind; i < argc; ++i)
 329                 if (strlen(argv[i]) > longest)
 330                         longest = strlen(argv[i]);
 331         {
 332                 register int    from;
 333                 register int    to;
 334
 335                 for (i = 0; environ[i] != NULL; ++i)
 336                         continue;
 337                 fakeenv = (char **) malloc((size_t) ((i + 2) *
 338                         sizeof *fakeenv));
 339                 if (fakeenv == NULL ||
 340                         (fakeenv[0] = (char *) malloc(longest + 4)) == NULL) {
 341                         err(EXIT_FAILURE, "Can't allocated %zu bytes",
 342                             longest + 4);
 343                 }
 344                 to = 0;
 345                 (void)strcpy(fakeenv[to++], "TZ=");     /* XXX strcpy is safe */
 346                 for (from = 0; environ[from] != NULL; ++from)
 347                         if (strncmp(environ[from], "TZ=", 3) != 0)
 348                                 fakeenv[to++] = environ[from];
 349                 fakeenv[to] = NULL;
 350                 environ = fakeenv;
 351         }
 352         for (i = optind; i < argc; ++i) {
 353                 static char     buf[MAX_STRING_LENGTH];
 354
 355                 (void) strcpy(&fakeenv[0][3], argv[i]); /* XXX strcpy is safe */
 356                 if (!vflag) {
 357                         show(argv[i], now, FALSE);
 358                         continue;
 359                 }
 360                 warned = FALSE;
 361                 t = absolute_min_time;
 362                 show(argv[i], t, TRUE);
 363                 t += SECSPERHOUR * HOURSPERDAY;
 364                 show(argv[i], t, TRUE);
 365                 if (t < cutlotime)
 366                         t = cutlotime;
 367                 tmp = my_localtime(&t);
 368                 if (tmp != NULL) {
 369                         tm = *tmp;
 370                         (void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
 371                 }
 372                 for ( ; ; ) {
 373                         if (t >= cuthitime || t >= cuthitime - SECSPERHOUR * 12)
 374                                 break;
 375                         newt = t + SECSPERHOUR * 12;
 376                         newtmp = localtime(&newt);
 377                         if (newtmp != NULL)
 378                                 newtm = *newtmp;
 379                         if ((tmp == NULL || newtmp == NULL) ? (tmp != newtmp) :
 380                                 (delta(&newtm, &tm) != (newt - t) ||
 381                                 newtm.tm_isdst != tm.tm_isdst ||
 382                                 strcmp(abbr(&newtm), buf) != 0)) {
 383                                         newt = hunt(argv[i], t, newt);
 384                                         newtmp = localtime(&newt);
 385                                         if (newtmp != NULL) {
 386                                                 newtm = *newtmp;
 387                                                 (void) strncpy(buf,
 388                                                         abbr(&newtm),
 389                                                         (sizeof buf) - 1);
 390                                         }
 391                         }
 392                         t = newt;
 393                         tm = newtm;
 394                         tmp = newtmp;
 395                 }
 396                 t = absolute_max_time;
 397                 t -= SECSPERHOUR * HOURSPERDAY;
 398                 show(argv[i], t, TRUE);
 399                 t += SECSPERHOUR * HOURSPERDAY;
 400                 show(argv[i], t, TRUE);
 401         }
 402         if (fflush(stdout) || ferror(stdout)) {
 403                 err(EXIT_FAILURE, _("Error writing standard output"));
 404         }
 405         exit(EXIT_SUCCESS);
 406         /* If exit fails to exit... */
 407         return EXIT_FAILURE;
 408 }
 409
 410 static time_t
 411 ovfl_check(time_t t)
 412 {
 413         if (t < 0 && t - 1 >= 0)
 414                 return t;
 415         else
 416                 return t - 1;
 417 }
 418
 419 static void
 420 setabsolutes(void)
 421 {
 422         if (0.5 == (time_t) 0.5) {
 423                 /*
 424                 ** time_t is floating.
 425                 */
 426                 if (sizeof (time_t) == sizeof (float)) {
 427                         absolute_min_time = (time_t) -FLT_MAX;
 428                         absolute_max_time = (time_t) FLT_MAX;
 429                 } else if (sizeof (time_t) == sizeof (double)) {
 430                         absolute_min_time = (time_t) -DBL_MAX;
 431                         absolute_max_time = (time_t) DBL_MAX;
 432                 } else {
 433                         (void) fprintf(stderr,
 434 _("%s: use of -v on system with floating time_t other than float or double\n"),
 435                                 progname);
 436                         exit(EXIT_FAILURE);
 437                 }
 438         } else if (0 > (time_t) -1) {
 439                 /*
 440                 ** time_t is signed.  Assume overflow wraps around.
 441                 */
 442                 time_t t = 0;
 443                 time_t t1 = 1;
 444
 445                 while (t < t1) {
 446                         t = t1;
 447                         t1 = 2 * t1 + 1;
 448                 }
 449
 450                 absolute_max_time = t;
 451                 t = -t;
 452                 absolute_min_time = ovfl_check(t);
 453         } else {
 454                 /*
 455                 ** time_t is unsigned.
 456                 */
 457                 absolute_min_time = 0;
 458                 absolute_max_time = absolute_min_time - 1;
 459         }
 460 }
 461
 462 static time_t
 463 yeartot(y)
 464 const long      y;
 465 {
 466         register long   myy;
 467         register long   seconds;
 468         register time_t t;
 469
 470         myy = EPOCH_YEAR;
 471         t = 0;
 472         while (myy != y) {
 473                 if (myy < y) {
 474                         seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
 475                         ++myy;
 476                         if (t > absolute_max_time - seconds) {
 477                                 t = absolute_max_time;
 478                                 break;
 479                         }
 480                         t += seconds;
 481                 } else {
 482                         --myy;
 483                         seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
 484                         if (t < absolute_min_time + seconds) {
 485                                 t = absolute_min_time;
 486                                 break;
 487                         }
 488                         t -= seconds;
 489                 }
 490         }
 491         return t;
 492 }
 493
 494 static time_t
 495 hunt(char *name, time_t lot, time_t hit)
 496 {
 497         time_t                  t;
 498         long                    diff;
 499         struct tm               lotm;
 500         register struct tm *    lotmp;
 501         struct tm               tm;
 502         register struct tm *    tmp;
 503         char                    loab[MAX_STRING_LENGTH];
 504
 505         lotmp = my_localtime(&lot);
 506         if (lotmp != NULL) {
 507                 lotm = *lotmp;
 508                 (void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
 509         }
 510         for ( ; ; ) {
 511                 diff = (long) (hit - lot);
 512                 if (diff < 2)
 513                         break;
 514                 t = lot;
 515                 t += diff / 2;
 516                 if (t <= lot)
 517                         ++t;
 518                 else if (t >= hit)
 519                         --t;
 520                 tmp = my_localtime(&t);
 521                 if (tmp != NULL)
 522                         tm = *tmp;
 523                 if ((lotmp == NULL || tmp == NULL) ? (lotmp == tmp) :
 524                         (delta(&tm, &lotm) == (t - lot) &&
 525                         tm.tm_isdst == lotm.tm_isdst &&
 526                         strcmp(abbr(&tm), loab) == 0)) {
 527                                 lot = t;
 528                                 lotm = tm;
 529                                 lotmp = tmp;
 530                 } else  hit = t;
 531         }
 532         show(name, lot, TRUE);
 533         show(name, hit, TRUE);
 534         return hit;
 535 }
 536
 537 /*
 538 ** Thanks to Paul Eggert for logic used in delta.
 539 */
 540
 541 static long
 542 delta(newp, oldp)
 543 struct tm *     newp;
 544 struct tm *     oldp;
 545 {
 546         register long   result;
 547         register int    tmy;
 548
 549         if (newp->tm_year < oldp->tm_year)
 550                 return -delta(oldp, newp);
 551         result = 0;
 552         for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
 553                 result += DAYSPERNYEAR + isleap_sum(tmy, TM_YEAR_BASE);
 554         result += newp->tm_yday - oldp->tm_yday;
 555         result *= HOURSPERDAY;
 556         result += newp->tm_hour - oldp->tm_hour;
 557         result *= MINSPERHOUR;
 558         result += newp->tm_min - oldp->tm_min;
 559         result *= SECSPERMIN;
 560         result += newp->tm_sec - oldp->tm_sec;
 561         return result;
 562 }
 563
 564 static void
 565 show(char *zone, time_t t, int v)
 566 {
 567         register struct tm *    tmp;
 568
 569         (void) printf("%-*s  ", (int) longest, zone);
 570         if (v) {
 571                 tmp = gmtime(&t);
 572                 if (tmp == NULL) {
 573                         (void) printf(tformat(), t);
 574                 } else {
 575                         dumptime(tmp);
 576                         (void) printf(" UTC");
 577                 }
 578                 (void) printf(" = ");
 579         }
 580         tmp = my_localtime(&t);
 581         dumptime(tmp);
 582         if (tmp != NULL) {
 583                 if (*abbr(tmp) != '\0')
 584                         (void) printf(" %s", abbr(tmp));
 585                 if (v) {
 586                         (void) printf(" isdst=%d", tmp->tm_isdst);
 587 #ifdef TM_GMTOFF
 588                         (void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
 589 #endif /* defined TM_GMTOFF */
 590                 }
 591         }
 592         (void) printf("\n");
 593         if (tmp != NULL && *abbr(tmp) != '\0')
 594                 abbrok(abbr(tmp), zone);
 595 }
 596
 597 static const char *
 598 abbr(tmp)
 599 struct tm *     tmp;
 600 {
 601         register const char *   result;
 602         static const char       nada;
 603
 604         if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
 605                 return &nada;
 606         result = tzname[tmp->tm_isdst];
 607         return (result == NULL) ? &nada : result;
 608 }
 609
 610 /*
 611 ** The code below can fail on certain theoretical systems;
 612 ** it works on all known real-world systems as of 2004-12-30.
 613 */
 614
 615 static const char *
 616 tformat(void)
 617 {
 618         if (0.5 == (time_t) 0.5) {      /* floating */
 619                 if (sizeof (time_t) > sizeof (double))
 620                         return "%Lg";
 621                 return "%g";
 622         }
 623         if (0 > (time_t) -1) {          /* signed */
 624                 if (sizeof (time_t) > sizeof (long))
 625                         return "%lld";
 626                 if (sizeof (time_t) > sizeof (int))
 627                         return "%ld";
 628                 return "%d";
 629         }
 630         if (sizeof (time_t) > sizeof (unsigned long))
 631                 return "%llu";
 632         if (sizeof (time_t) > sizeof (unsigned int))
 633                 return "%lu";
 634         return "%u";
 635 }
 636
 637 static void
 638 dumptime(timeptr)
 639 register const struct tm *      timeptr;
 640 {
 641         static const char       wday_name[][3] = {
 642                 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
 643         };
 644         static const char       mon_name[][3] = {
 645                 "Jan", "Feb", "Mar", "Apr", "May", "Jun",
 646                 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
 647         };
 648         register const char *   wn;
 649         register const char *   mn;
 650         register int            lead;
 651         register int            trail;
 652
 653         if (timeptr == NULL) {
 654                 (void) printf("NULL");
 655                 return;
 656         }
 657         /*
 658         ** The packaged versions of localtime and gmtime never put out-of-range
 659         ** values in tm_wday or tm_mon, but since this code might be compiled
 660         ** with other (perhaps experimental) versions, paranoia is in order.
 661         */
 662         if (timeptr->tm_wday < 0 || timeptr->tm_wday >=
 663                 (int) (sizeof wday_name / sizeof wday_name[0]))
 664                         wn = "???";
 665         else            wn = wday_name[timeptr->tm_wday];
 666         if (timeptr->tm_mon < 0 || timeptr->tm_mon >=
 667                 (int) (sizeof mon_name / sizeof mon_name[0]))
 668                         mn = "???";
 669         else            mn = mon_name[timeptr->tm_mon];
 670         (void) printf("%.3s %.3s%3d %.2d:%.2d:%.2d ",
 671                 wn, mn,
 672                 timeptr->tm_mday, timeptr->tm_hour,
 673                 timeptr->tm_min, timeptr->tm_sec);
 674 #define DIVISOR 10
 675         trail = timeptr->tm_year % DIVISOR + TM_YEAR_BASE % DIVISOR;
 676         lead = timeptr->tm_year / DIVISOR + TM_YEAR_BASE / DIVISOR +
 677                 trail / DIVISOR;
 678         trail %= DIVISOR;
 679         if (trail < 0 && lead > 0) {
 680                 trail += DIVISOR;
 681                 --lead;
 682         } else if (lead < 0 && trail > 0) {
 683                 trail -= DIVISOR;
 684                 ++lead;
 685         }
 686         if (lead == 0)
 687                 (void) printf("%d", trail);
 688         else    (void) printf("%d%d", lead, ((trail < 0) ? -trail : trail));
 689 }