timezone/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 #include "version.h"
   7
   8 /*
   9 ** This code has been made independent of the rest of the time
  10 ** conversion package to increase confidence in the verification it provides.
  11 ** You can use this code to help in verifying other implementations.
  12 **
  13 ** However, include private.h when debugging, so that it overrides
  14 ** time_t consistently with the rest of the package.
  15 */
  16
  17 #ifdef time_tz
  18 # include "private.h"
  19 #endif
  20
  21 #include "stdio.h"      /* for stdout, stderr, perror */
  22 #include "string.h"     /* for strcpy */
  23 #include "sys/types.h"  /* for time_t */
  24 #include "time.h"       /* for struct tm */
  25 #include "stdlib.h"     /* for exit, malloc, atoi */
  26 #include "limits.h"     /* for CHAR_BIT, LLONG_MAX */
  27 #include "ctype.h"      /* for isalpha et al. */
  28 #ifndef isascii
  29 #define isascii(x) 1
  30 #endif /* !defined isascii */
  31
  32 /*
  33 ** Substitutes for pre-C99 compilers.
  34 ** Much of this section of code is stolen from private.h.
  35 */
  36
  37 #ifndef HAVE_STDINT_H
  38 # define HAVE_STDINT_H \
  39     (199901 <= __STDC_VERSION__ \
  40      || 2 < __GLIBC__ + (1 <= __GLIBC_MINOR__)  \
  41      || __CYGWIN__)
  42 #endif
  43 #if HAVE_STDINT_H
  44 # include "stdint.h"
  45 #endif
  46 #ifndef HAVE_INTTYPES_H
  47 # define HAVE_INTTYPES_H HAVE_STDINT_H
  48 #endif
  49 #if HAVE_INTTYPES_H
  50 # include <inttypes.h>
  51 #endif
  52
  53 #ifndef INT_FAST32_MAX
  54 # if INT_MAX >> 31 == 0
  55 typedef long int_fast32_t;
  56 # else
  57 typedef int int_fast32_t;
  58 # endif
  59 #endif
  60
  61 #ifndef INTMAX_MAX
  62 # if defined LLONG_MAX || defined __LONG_LONG_MAX__
  63 typedef long long intmax_t;
  64 #  define strtoimax strtoll
  65 #  define PRIdMAX "lld"
  66 #  ifdef LLONG_MAX
  67 #   define INTMAX_MAX LLONG_MAX
  68 #  else
  69 #   define INTMAX_MAX __LONG_LONG_MAX__
  70 #  endif
  71 # else
  72 typedef long intmax_t;
  73 #  define strtoimax strtol
  74 #  define PRIdMAX "ld"
  75 #  define INTMAX_MAX LONG_MAX
  76 # endif
  77 #endif
  78
  79
  80 #ifndef ZDUMP_LO_YEAR
  81 #define ZDUMP_LO_YEAR   (-500)
  82 #endif /* !defined ZDUMP_LO_YEAR */
  83
  84 #ifndef ZDUMP_HI_YEAR
  85 #define ZDUMP_HI_YEAR   2500
  86 #endif /* !defined ZDUMP_HI_YEAR */
  87
  88 #ifndef MAX_STRING_LENGTH
  89 #define MAX_STRING_LENGTH       1024
  90 #endif /* !defined MAX_STRING_LENGTH */
  91
  92 #ifndef TRUE
  93 #define TRUE            1
  94 #endif /* !defined TRUE */
  95
  96 #ifndef FALSE
  97 #define FALSE           0
  98 #endif /* !defined FALSE */
  99
 100 #ifndef EXIT_SUCCESS
 101 #define EXIT_SUCCESS    0
 102 #endif /* !defined EXIT_SUCCESS */
 103
 104 #ifndef EXIT_FAILURE
 105 #define EXIT_FAILURE    1
 106 #endif /* !defined EXIT_FAILURE */
 107
 108 #ifndef SECSPERMIN
 109 #define SECSPERMIN      60
 110 #endif /* !defined SECSPERMIN */
 111
 112 #ifndef MINSPERHOUR
 113 #define MINSPERHOUR     60
 114 #endif /* !defined MINSPERHOUR */
 115
 116 #ifndef SECSPERHOUR
 117 #define SECSPERHOUR     (SECSPERMIN * MINSPERHOUR)
 118 #endif /* !defined SECSPERHOUR */
 119
 120 #ifndef HOURSPERDAY
 121 #define HOURSPERDAY     24
 122 #endif /* !defined HOURSPERDAY */
 123
 124 #ifndef EPOCH_YEAR
 125 #define EPOCH_YEAR      1970
 126 #endif /* !defined EPOCH_YEAR */
 127
 128 #ifndef TM_YEAR_BASE
 129 #define TM_YEAR_BASE    1900
 130 #endif /* !defined TM_YEAR_BASE */
 131
 132 #ifndef DAYSPERNYEAR
 133 #define DAYSPERNYEAR    365
 134 #endif /* !defined DAYSPERNYEAR */
 135
 136 #ifndef isleap
 137 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
 138 #endif /* !defined isleap */
 139
 140 #ifndef isleap_sum
 141 /*
 142 ** See tzfile.h for details on isleap_sum.
 143 */
 144 #define isleap_sum(a, b)        isleap((a) % 400 + (b) % 400)
 145 #endif /* !defined isleap_sum */
 146
 147 #define SECSPERDAY      ((int_fast32_t) SECSPERHOUR * HOURSPERDAY)
 148 #define SECSPERNYEAR    (SECSPERDAY * DAYSPERNYEAR)
 149 #define SECSPERLYEAR    (SECSPERNYEAR + SECSPERDAY)
 150 #define SECSPER400YEARS (SECSPERNYEAR * (intmax_t) (300 + 3)    \
 151                          + SECSPERLYEAR * (intmax_t) (100 - 3))
 152
 153 /*
 154 ** True if SECSPER400YEARS is known to be representable as an
 155 ** intmax_t.  It's OK that SECSPER400YEARS_FITS can in theory be false
 156 ** even if SECSPER400YEARS is representable, because when that happens
 157 ** the code merely runs a bit more slowly, and this slowness doesn't
 158 ** occur on any practical platform.
 159 */
 160 enum { SECSPER400YEARS_FITS = SECSPERLYEAR <= INTMAX_MAX / 400 };
 161
 162 #ifndef HAVE_GETTEXT
 163 #define HAVE_GETTEXT 0
 164 #endif
 165 #if HAVE_GETTEXT
 166 #include "locale.h"     /* for setlocale */
 167 #include "libintl.h"
 168 #endif /* HAVE_GETTEXT */
 169
 170 #ifndef GNUC_or_lint
 171 #ifdef lint
 172 #define GNUC_or_lint
 173 #else /* !defined lint */
 174 #ifdef __GNUC__
 175 #define GNUC_or_lint
 176 #endif /* defined __GNUC__ */
 177 #endif /* !defined lint */
 178 #endif /* !defined GNUC_or_lint */
 179
 180 #if 2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__)
 181 # define ATTRIBUTE_PURE __attribute__ ((__pure__))
 182 #else
 183 # define ATTRIBUTE_PURE /* empty */
 184 #endif
 185
 186 /*
 187 ** For the benefit of GNU folk...
 188 ** `_(MSGID)' uses the current locale's message library string for MSGID.
 189 ** The default is to use gettext if available, and use MSGID otherwise.
 190 */
 191
 192 #ifndef _
 193 #if HAVE_GETTEXT
 194 #define _(msgid) gettext(msgid)
 195 #else /* !HAVE_GETTEXT */
 196 #define _(msgid) msgid
 197 #endif /* !HAVE_GETTEXT */
 198 #endif /* !defined _ */
 199
 200 #ifndef TZ_DOMAIN
 201 #define TZ_DOMAIN "tz"
 202 #endif /* !defined TZ_DOMAIN */
 203
 204 extern char **  environ;
 205 extern int      getopt(int argc, char * const argv[],
 206                         const char * options);
 207 extern char *   optarg;
 208 extern int      optind;
 209 extern char *   tzname[2];
 210
 211 /* The minimum and maximum finite time values.  */
 212 static time_t const absolute_min_time =
 213   ((time_t) -1 < 0
 214    ? (time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1)
 215    : 0);
 216 static time_t const absolute_max_time =
 217   ((time_t) -1 < 0
 218    ? - (~ 0 < 0) - ((time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1))
 219    : -1);
 220 static size_t   longest;
 221 static char *   progname;
 222 static int      warned;
 223
 224 static char *   abbr(struct tm * tmp);
 225 static void     abbrok(const char * abbrp, const char * zone);
 226 static intmax_t delta(struct tm * newp, struct tm * oldp) ATTRIBUTE_PURE;
 227 static void     dumptime(const struct tm * tmp);
 228 static time_t   hunt(char * name, time_t lot, time_t    hit);
 229 static void     show(char * zone, time_t t, int v);
 230 static const char *     tformat(void);
 231 static time_t   yeartot(intmax_t y) ATTRIBUTE_PURE;
 232
 233 #ifndef TYPECHECK
 234 #define my_localtime    localtime
 235 #else /* !defined TYPECHECK */
 236 static struct tm *
 237 my_localtime(time_t *tp)
 238 {
 239         register struct tm *    tmp;
 240
 241         tmp = localtime(tp);
 242         if (tp != NULL && tmp != NULL) {
 243                 struct tm       tm;
 244                 register time_t t;
 245
 246                 tm = *tmp;
 247                 t = mktime(&tm);
 248                 if (t != *tp) {
 249                         (void) fflush(stdout);
 250                         (void) fprintf(stderr, "\n%s: ", progname);
 251                         (void) fprintf(stderr, tformat(), *tp);
 252                         (void) fprintf(stderr, " ->");
 253                         (void) fprintf(stderr, " year=%d", tmp->tm_year);
 254                         (void) fprintf(stderr, " mon=%d", tmp->tm_mon);
 255                         (void) fprintf(stderr, " mday=%d", tmp->tm_mday);
 256                         (void) fprintf(stderr, " hour=%d", tmp->tm_hour);
 257                         (void) fprintf(stderr, " min=%d", tmp->tm_min);
 258                         (void) fprintf(stderr, " sec=%d", tmp->tm_sec);
 259                         (void) fprintf(stderr, " isdst=%d", tmp->tm_isdst);
 260                         (void) fprintf(stderr, " -> ");
 261                         (void) fprintf(stderr, tformat(), t);
 262                         (void) fprintf(stderr, "\n");
 263                 }
 264         }
 265         return tmp;
 266 }
 267 #endif /* !defined TYPECHECK */
 268
 269 static void
 270 abbrok(const char *const abbrp, const char *const zone)
 271 {
 272         register const char *   cp;
 273         register const char *   wp;
 274
 275         if (warned)
 276                 return;
 277         cp = abbrp;
 278         wp = NULL;
 279         while (isascii((unsigned char) *cp) && isalpha((unsigned char) *cp))
 280                 ++cp;
 281         if (cp - abbrp == 0)
 282                 wp = _("lacks alphabetic at start");
 283         else if (cp - abbrp < 3)
 284                 wp = _("has fewer than 3 alphabetics");
 285         else if (cp - abbrp > 6)
 286                 wp = _("has more than 6 alphabetics");
 287         if (wp == NULL && (*cp == '+' || *cp == '-')) {
 288                 ++cp;
 289                 if (isascii((unsigned char) *cp) &&
 290                         isdigit((unsigned char) *cp))
 291                                 if (*cp++ == '1' && *cp >= '0' && *cp <= '4')
 292                                         ++cp;
 293                 if (*cp != '\0')
 294                         wp = _("differs from POSIX standard");
 295         }
 296         if (wp == NULL)
 297                 return;
 298         (void) fflush(stdout);
 299         (void) fprintf(stderr,
 300                 _("%s: warning: zone \"%s\" abbreviation \"%s\" %s\n"),
 301                 progname, zone, abbrp, wp);
 302         warned = TRUE;
 303 }
 304
 305 static void
 306 usage(FILE * const stream, const int status)
 307 {
 308         (void) fprintf(stream,
 309 _("%s: usage: %s [--version] [--help] [-{vV}] [-{ct} [lo,]hi] zonename ...\n"
 310   "\n"
 311   "Report bugs to %s.\n"),
 312                        progname, progname, REPORT_BUGS_TO);
 313         exit(status);
 314 }
 315
 316 int
 317 main(int argc, char *argv[])
 318 {
 319         register int            i;
 320         register int            vflag;
 321         register int            Vflag;
 322         register char *         cutarg;
 323         register char *         cuttimes;
 324         register time_t         cutlotime;
 325         register time_t         cuthitime;
 326         register char **        fakeenv;
 327         time_t                  now;
 328         time_t                  t;
 329         time_t                  newt;
 330         struct tm               tm;
 331         struct tm               newtm;
 332         register struct tm *    tmp;
 333         register struct tm *    newtmp;
 334
 335         cutlotime = absolute_min_time;
 336         cuthitime = absolute_max_time;
 337 #if HAVE_GETTEXT
 338         (void) setlocale(LC_ALL, "");
 339 #ifdef TZ_DOMAINDIR
 340         (void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
 341 #endif /* defined TEXTDOMAINDIR */
 342         (void) textdomain(TZ_DOMAIN);
 343 #endif /* HAVE_GETTEXT */
 344         progname = argv[0];
 345         for (i = 1; i < argc; ++i)
 346                 if (strcmp(argv[i], "--version") == 0) {
 347                         (void) printf("zdump %s%s\n", PKGVERSION, TZVERSION);
 348                         exit(EXIT_SUCCESS);
 349                 } else if (strcmp(argv[i], "--help") == 0) {
 350                         usage(stdout, EXIT_SUCCESS);
 351                 }
 352         vflag = Vflag = 0;
 353         cutarg = cuttimes = NULL;
 354         for (;;)
 355           switch (getopt(argc, argv, "c:t:vV")) {
 356           case 'c': cutarg = optarg; break;
 357           case 't': cuttimes = optarg; break;
 358           case 'v': vflag = 1; break;
 359           case 'V': Vflag = 1; break;
 360           case -1:
 361             if (! (optind == argc - 1 && strcmp(argv[optind], "=") == 0))
 362               goto arg_processing_done;
 363             /* Fall through.  */
 364           default:
 365             usage(stderr, EXIT_FAILURE);
 366           }
 367  arg_processing_done:;
 368
 369         if (vflag | Vflag) {
 370                 intmax_t        lo;
 371                 intmax_t        hi;
 372                 char *loend, *hiend;
 373                 register intmax_t cutloyear = ZDUMP_LO_YEAR;
 374                 register intmax_t cuthiyear = ZDUMP_HI_YEAR;
 375                 if (cutarg != NULL) {
 376                         lo = strtoimax(cutarg, &loend, 10);
 377                         if (cutarg != loend && !*loend) {
 378                                 hi = lo;
 379                                 cuthiyear = hi;
 380                         } else if (cutarg != loend && *loend == ','
 381                                    && (hi = strtoimax(loend + 1, &hiend, 10),
 382                                        loend + 1 != hiend && !*hiend)) {
 383                                 cutloyear = lo;
 384                                 cuthiyear = hi;
 385                         } else {
 386 (void) fprintf(stderr, _("%s: wild -c argument %s\n"),
 387                                         progname, cutarg);
 388                                 exit(EXIT_FAILURE);
 389                         }
 390                 }
 391                 if (cutarg != NULL || cuttimes == NULL) {
 392                         cutlotime = yeartot(cutloyear);
 393                         cuthitime = yeartot(cuthiyear);
 394                 }
 395                 if (cuttimes != NULL) {
 396                         lo = strtoimax(cuttimes, &loend, 10);
 397                         if (cuttimes != loend && !*loend) {
 398                                 hi = lo;
 399                                 if (hi < cuthitime) {
 400                                         if (hi < absolute_min_time)
 401                                                 hi = absolute_min_time;
 402                                         cuthitime = hi;
 403                                 }
 404                         } else if (cuttimes != loend && *loend == ','
 405                                    && (hi = strtoimax(loend + 1, &hiend, 10),
 406                                        loend + 1 != hiend && !*hiend)) {
 407                                 if (cutlotime < lo) {
 408                                         if (absolute_max_time < lo)
 409                                                 lo = absolute_max_time;
 410                                         cutlotime = lo;
 411                                 }
 412                                 if (hi < cuthitime) {
 413                                         if (hi < absolute_min_time)
 414                                                 hi = absolute_min_time;
 415                                         cuthitime = hi;
 416                                 }
 417                         } else {
 418                                 (void) fprintf(stderr,
 419                                         _("%s: wild -t argument %s\n"),
 420                                         progname, cuttimes);
 421                                 exit(EXIT_FAILURE);
 422                         }
 423                 }
 424         }
 425         (void) time(&now);
 426         longest = 0;
 427         for (i = optind; i < argc; ++i)
 428                 if (strlen(argv[i]) > longest)
 429                         longest = strlen(argv[i]);
 430         {
 431                 register int    from;
 432                 register int    to;
 433
 434                 for (i = 0; environ[i] != NULL; ++i)
 435                         continue;
 436                 fakeenv = malloc((i + 2) * sizeof *fakeenv);
 437                 if (fakeenv == NULL
 438                     || (fakeenv[0] = malloc(longest + 4)) == NULL) {
 439                                         (void) perror(progname);
 440                                         exit(EXIT_FAILURE);
 441                 }
 442                 to = 0;
 443                 (void) strcpy(fakeenv[to++], "TZ=");
 444                 for (from = 0; environ[from] != NULL; ++from)
 445                         if (strncmp(environ[from], "TZ=", 3) != 0)
 446                                 fakeenv[to++] = environ[from];
 447                 fakeenv[to] = NULL;
 448                 environ = fakeenv;
 449         }
 450         for (i = optind; i < argc; ++i) {
 451                 static char     buf[MAX_STRING_LENGTH];
 452
 453                 (void) strcpy(&fakeenv[0][3], argv[i]);
 454                 if (! (vflag | Vflag)) {
 455                         show(argv[i], now, FALSE);
 456                         continue;
 457                 }
 458                 warned = FALSE;
 459                 t = absolute_min_time;
 460                 if (!Vflag) {
 461                         show(argv[i], t, TRUE);
 462                         t += SECSPERDAY;
 463                         show(argv[i], t, TRUE);
 464                 }
 465                 if (t < cutlotime)
 466                         t = cutlotime;
 467                 tmp = my_localtime(&t);
 468                 if (tmp != NULL) {
 469                         tm = *tmp;
 470                         (void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
 471                 }
 472                 for ( ; ; ) {
 473                         newt = (t < absolute_max_time - SECSPERDAY / 2
 474                                 ? t + SECSPERDAY / 2
 475                                 : absolute_max_time);
 476                         if (cuthitime <= newt)
 477                                 break;
 478                         newtmp = localtime(&newt);
 479                         if (newtmp != NULL)
 480                                 newtm = *newtmp;
 481                         if ((tmp == NULL || newtmp == NULL) ? (tmp != newtmp) :
 482                                 (delta(&newtm, &tm) != (newt - t) ||
 483                                 newtm.tm_isdst != tm.tm_isdst ||
 484                                 strcmp(abbr(&newtm), buf) != 0)) {
 485                                         newt = hunt(argv[i], t, newt);
 486                                         newtmp = localtime(&newt);
 487                                         if (newtmp != NULL) {
 488                                                 newtm = *newtmp;
 489                                                 (void) strncpy(buf,
 490                                                         abbr(&newtm),
 491                                                         (sizeof buf) - 1);
 492                                         }
 493                         }
 494                         t = newt;
 495                         tm = newtm;
 496                         tmp = newtmp;
 497                 }
 498                 if (!Vflag) {
 499                         t = absolute_max_time;
 500                         t -= SECSPERDAY;
 501                         show(argv[i], t, TRUE);
 502                         t += SECSPERDAY;
 503                         show(argv[i], t, TRUE);
 504                 }
 505         }
 506         if (fflush(stdout) || ferror(stdout)) {
 507                 (void) fprintf(stderr, "%s: ", progname);
 508                 (void) perror(_("Error writing to standard output"));
 509                 exit(EXIT_FAILURE);
 510         }
 511         exit(EXIT_SUCCESS);
 512         /* If exit fails to exit... */
 513         return EXIT_FAILURE;
 514 }
 515
 516 static time_t
 517 yeartot(const intmax_t y)
 518 {
 519         register intmax_t       myy, seconds, years;
 520         register time_t         t;
 521
 522         myy = EPOCH_YEAR;
 523         t = 0;
 524         while (myy < y) {
 525                 if (SECSPER400YEARS_FITS && 400 <= y - myy) {
 526                         intmax_t diff400 = (y - myy) / 400;
 527                         if (INTMAX_MAX / SECSPER400YEARS < diff400)
 528                                 return absolute_max_time;
 529                         seconds = diff400 * SECSPER400YEARS;
 530                         years = diff400 * 400;
 531                 } else {
 532                         seconds = isleap(myy) ? SECSPERLYEAR : SECSPERNYEAR;
 533                         years = 1;
 534                 }
 535                 myy += years;
 536                 if (t > absolute_max_time - seconds)
 537                         return absolute_max_time;
 538                 t += seconds;
 539         }
 540         while (y < myy) {
 541                 if (SECSPER400YEARS_FITS && y + 400 <= myy && myy < 0) {
 542                         intmax_t diff400 = (myy - y) / 400;
 543                         if (INTMAX_MAX / SECSPER400YEARS < diff400)
 544                                 return absolute_min_time;
 545                         seconds = diff400 * SECSPER400YEARS;
 546                         years = diff400 * 400;
 547                 } else {
 548                         seconds = isleap(myy - 1) ? SECSPERLYEAR : SECSPERNYEAR;
 549                         years = 1;
 550                 }
 551                 myy -= years;
 552                 if (t < absolute_min_time + seconds)
 553                         return absolute_min_time;
 554                 t -= seconds;
 555         }
 556         return t;
 557 }
 558
 559 static time_t
 560 hunt(char *name, time_t lot, time_t hit)
 561 {
 562         time_t                  t;
 563         struct tm               lotm;
 564         register struct tm *    lotmp;
 565         struct tm               tm;
 566         register struct tm *    tmp;
 567         char                    loab[MAX_STRING_LENGTH];
 568
 569         lotmp = my_localtime(&lot);
 570         if (lotmp != NULL) {
 571                 lotm = *lotmp;
 572                 (void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
 573         }
 574         for ( ; ; ) {
 575                 time_t diff = hit - lot;
 576                 if (diff < 2)
 577                         break;
 578                 t = lot;
 579                 t += diff / 2;
 580                 if (t <= lot)
 581                         ++t;
 582                 else if (t >= hit)
 583                         --t;
 584                 tmp = my_localtime(&t);
 585                 if (tmp != NULL)
 586                         tm = *tmp;
 587                 if ((lotmp == NULL || tmp == NULL) ? (lotmp == tmp) :
 588                         (delta(&tm, &lotm) == (t - lot) &&
 589                         tm.tm_isdst == lotm.tm_isdst &&
 590                         strcmp(abbr(&tm), loab) == 0)) {
 591                                 lot = t;
 592                                 lotm = tm;
 593                                 lotmp = tmp;
 594                 } else  hit = t;
 595         }
 596         show(name, lot, TRUE);
 597         show(name, hit, TRUE);
 598         return hit;
 599 }
 600
 601 /*
 602 ** Thanks to Paul Eggert for logic used in delta.
 603 */
 604
 605 static intmax_t
 606 delta(struct tm * newp, struct tm *oldp)
 607 {
 608         register intmax_t       result;
 609         register int            tmy;
 610
 611         if (newp->tm_year < oldp->tm_year)
 612                 return -delta(oldp, newp);
 613         result = 0;
 614         for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
 615                 result += DAYSPERNYEAR + isleap_sum(tmy, TM_YEAR_BASE);
 616         result += newp->tm_yday - oldp->tm_yday;
 617         result *= HOURSPERDAY;
 618         result += newp->tm_hour - oldp->tm_hour;
 619         result *= MINSPERHOUR;
 620         result += newp->tm_min - oldp->tm_min;
 621         result *= SECSPERMIN;
 622         result += newp->tm_sec - oldp->tm_sec;
 623         return result;
 624 }
 625
 626 static void
 627 show(char *zone, time_t t, int v)
 628 {
 629         register struct tm *    tmp;
 630
 631         (void) printf("%-*s  ", (int) longest, zone);
 632         if (v) {
 633                 tmp = gmtime(&t);
 634                 if (tmp == NULL) {
 635                         (void) printf(tformat(), t);
 636                 } else {
 637                         dumptime(tmp);
 638                         (void) printf(" UT");
 639                 }
 640                 (void) printf(" = ");
 641         }
 642         tmp = my_localtime(&t);
 643         dumptime(tmp);
 644         if (tmp != NULL) {
 645                 if (*abbr(tmp) != '\0')
 646                         (void) printf(" %s", abbr(tmp));
 647                 if (v) {
 648                         (void) printf(" isdst=%d", tmp->tm_isdst);
 649 #ifdef TM_GMTOFF
 650                         (void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
 651 #endif /* defined TM_GMTOFF */
 652                 }
 653         }
 654         (void) printf("\n");
 655         if (tmp != NULL && *abbr(tmp) != '\0')
 656                 abbrok(abbr(tmp), zone);
 657 }
 658
 659 static char *
 660 abbr(struct tm *tmp)
 661 {
 662         register char * result;
 663         static char     nada;
 664
 665         if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
 666                 return &nada;
 667         result = tzname[tmp->tm_isdst];
 668         return (result == NULL) ? &nada : result;
 669 }
 670
 671 /*
 672 ** The code below can fail on certain theoretical systems;
 673 ** it works on all known real-world systems as of 2004-12-30.
 674 */
 675
 676 static const char *
 677 tformat(void)
 678 {
 679         if (0 > (time_t) -1) {          /* signed */
 680                 if (sizeof (time_t) == sizeof (intmax_t))
 681                         return "%"PRIdMAX;
 682                 if (sizeof (time_t) > sizeof (long))
 683                         return "%lld";
 684                 if (sizeof (time_t) > sizeof (int))
 685                         return "%ld";
 686                 return "%d";
 687         }
 688 #ifdef PRIuMAX
 689         if (sizeof (time_t) == sizeof (uintmax_t))
 690                 return "%"PRIuMAX;
 691 #endif
 692         if (sizeof (time_t) > sizeof (unsigned long))
 693                 return "%llu";
 694         if (sizeof (time_t) > sizeof (unsigned int))
 695                 return "%lu";
 696         return "%u";
 697 }
 698
 699 static void
 700 dumptime(register const struct tm *timeptr)
 701 {
 702         static const char       wday_name[][3] = {
 703                 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
 704         };
 705         static const char       mon_name[][3] = {
 706                 "Jan", "Feb", "Mar", "Apr", "May", "Jun",
 707                 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
 708         };
 709         register const char *   wn;
 710         register const char *   mn;
 711         register int            lead;
 712         register int            trail;
 713
 714         if (timeptr == NULL) {
 715                 (void) printf("NULL");
 716                 return;
 717         }
 718         /*
 719         ** The packaged versions of localtime and gmtime never put out-of-range
 720         ** values in tm_wday or tm_mon, but since this code might be compiled
 721         ** with other (perhaps experimental) versions, paranoia is in order.
 722         */
 723         if (timeptr->tm_wday < 0 || timeptr->tm_wday >=
 724                 (int) (sizeof wday_name / sizeof wday_name[0]))
 725                         wn = "???";
 726         else            wn = wday_name[timeptr->tm_wday];
 727         if (timeptr->tm_mon < 0 || timeptr->tm_mon >=
 728                 (int) (sizeof mon_name / sizeof mon_name[0]))
 729                         mn = "???";
 730         else            mn = mon_name[timeptr->tm_mon];
 731         (void) printf("%.3s %.3s%3d %.2d:%.2d:%.2d ",
 732                 wn, mn,
 733                 timeptr->tm_mday, timeptr->tm_hour,
 734                 timeptr->tm_min, timeptr->tm_sec);
 735 #define DIVISOR 10
 736         trail = timeptr->tm_year % DIVISOR + TM_YEAR_BASE % DIVISOR;
 737         lead = timeptr->tm_year / DIVISOR + TM_YEAR_BASE / DIVISOR +
 738                 trail / DIVISOR;
 739         trail %= DIVISOR;
 740         if (trail < 0 && lead > 0) {
 741                 trail += DIVISOR;
 742                 --lead;
 743         } else if (lead < 0 && trail > 0) {
 744                 trail -= DIVISOR;
 745                 ++lead;
 746         }
 747         if (lead == 0)
 748                 (void) printf("%d", trail);
 749         else    (void) printf("%d%d", lead, ((trail < 0) ? -trail : trail));
 750 }