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zdump.c

#ifndef lint
#ifndef NOID
static char elsieid[] = "@(#)zdump.c      7.29";
#endif /* !defined NOID */
#endif /* !defined lint */

/*
** This code has been made independent of the rest of the time
** conversion package to increase confidence in the verification it provides.
** You can use this code to help in verifying other implementations.
*/

#include "stdio.h"      /* for stdout, stderr, perror */
#include "string.h"     /* for strcpy */
#include "sys/types.h"  /* for time_t */
#include "time.h" /* for struct tm */
#include "stdlib.h"     /* for exit, malloc, atoi */

#ifndef MAX_STRING_LENGTH
#define MAX_STRING_LENGTH     1024
#endif /* !defined MAX_STRING_LENGTH */

#ifndef TRUE
#define TRUE            1
#endif /* !defined TRUE */

#ifndef FALSE
#define FALSE           0
#endif /* !defined FALSE */

#ifndef EXIT_SUCCESS
#define EXIT_SUCCESS    0
#endif /* !defined EXIT_SUCCESS */

#ifndef EXIT_FAILURE
#define EXIT_FAILURE    1
#endif /* !defined EXIT_FAILURE */

#ifndef SECSPERMIN
#define SECSPERMIN      60
#endif /* !defined SECSPERMIN */

#ifndef MINSPERHOUR
#define MINSPERHOUR     60
#endif /* !defined MINSPERHOUR */

#ifndef SECSPERHOUR
#define SECSPERHOUR     (SECSPERMIN * MINSPERHOUR)
#endif /* !defined SECSPERHOUR */

#ifndef HOURSPERDAY
#define HOURSPERDAY     24
#endif /* !defined HOURSPERDAY */

#ifndef EPOCH_YEAR
#define EPOCH_YEAR      1970
#endif /* !defined EPOCH_YEAR */

#ifndef TM_YEAR_BASE
#define TM_YEAR_BASE    1900
#endif /* !defined TM_YEAR_BASE */

#ifndef DAYSPERNYEAR
#define DAYSPERNYEAR    365
#endif /* !defined DAYSPERNYEAR */

#ifndef isleap
#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
#endif /* !defined isleap */

#if HAVE_GETTEXT - 0
#include "locale.h"     /* for setlocale */
#include "libintl.h"
#endif /* HAVE_GETTEXT - 0 */

#ifndef GNUC_or_lint
#ifdef lint
#define GNUC_or_lint
#endif /* defined lint */
#ifndef lint
#ifdef __GNUC__
#define GNUC_or_lint
#endif /* defined __GNUC__ */
#endif /* !defined lint */
#endif /* !defined GNUC_or_lint */

#ifndef INITIALIZE
#ifdef GNUC_or_lint
#define INITIALIZE(x)   ((x) = 0)
#endif /* defined GNUC_or_lint */
#ifndef GNUC_or_lint
#define INITIALIZE(x)
#endif /* !defined GNUC_or_lint */
#endif /* !defined INITIALIZE */

/*
** For the benefit of GNU folk...
** `_(MSGID)' uses the current locale's message library string for MSGID.
** The default is to use gettext if available, and use MSGID otherwise.
*/

#ifndef _
#if HAVE_GETTEXT - 0
#define _(msgid) gettext(msgid)
#else /* !(HAVE_GETTEXT - 0) */
#define _(msgid) msgid
#endif /* !(HAVE_GETTEXT - 0) */
#endif /* !defined _ */

#ifndef TZ_DOMAIN
#define TZ_DOMAIN "tz"
#endif /* !defined TZ_DOMAIN */

#ifndef P
#ifdef __STDC__
#define P(x)      x
#endif /* defined __STDC__ */
#ifndef __STDC__
#define P(x)      ()
#endif /* !defined __STDC__ */
#endif /* !defined P */

extern char **    environ;
extern int  getopt P((int argc, char * const argv[],
                    const char * options));
extern char *     optarg;
extern int  optind;
extern char *     tzname[2];

static char *     abbr P((struct tm * tmp));
static long delta P((struct tm * newp, struct tm * oldp));
static time_t     hunt P((char * name, time_t lot, time_t   hit));
static size_t     longest;
static char *     progname;
static void show P((char * zone, time_t t, int v));

int
main(argc, argv)
int   argc;
char *      argv[];
{
      register int            i;
      register int            c;
      register int            vflag;
      register char *         cutoff;
      register int            cutyear;
      register long           cuttime;
      char **                 fakeenv;
      time_t                  now;
      time_t                  t;
      time_t                  newt;
      time_t                  hibit;
      struct tm         tm;
      struct tm         newtm;

      INITIALIZE(cuttime);
#if HAVE_GETTEXT - 0
      (void) setlocale(LC_CTYPE, "");
      (void) setlocale(LC_MESSAGES, "");
#ifdef TZ_DOMAINDIR
      (void) bindtextdomain(TZ_DOMAIN, TZ_DOMAINDIR);
#endif /* defined(TEXTDOMAINDIR) */
      (void) textdomain(TZ_DOMAIN);
#endif /* HAVE_GETTEXT - 0 */
      progname = argv[0];
      vflag = 0;
      cutoff = NULL;
      while ((c = getopt(argc, argv, "c:v")) == 'c' || c == 'v')
            if (c == 'v')
                  vflag = 1;
            else  cutoff = optarg;
      if ((c != EOF && c != -1) ||
            (optind == argc - 1 && strcmp(argv[optind], "=") == 0)) {
                  (void) fprintf(stderr,
_("%s: usage is %s [ -v ] [ -c cutoff ] zonename ...\n"),
                        argv[0], argv[0]);
                  (void) exit(EXIT_FAILURE);
      }
      if (cutoff != NULL) {
            int   y;

            cutyear = atoi(cutoff);
            cuttime = 0;
            for (y = EPOCH_YEAR; y < cutyear; ++y)
                  cuttime += DAYSPERNYEAR + isleap(y);
            cuttime *= SECSPERHOUR * HOURSPERDAY;
      }
      (void) time(&now);
      longest = 0;
      for (i = optind; i < argc; ++i)
            if (strlen(argv[i]) > longest)
                  longest = strlen(argv[i]);
      for (hibit = 1; (hibit << 1) != 0; hibit <<= 1)
            continue;
      {
            register int      from;
            register int      to;

            for (i = 0;  environ[i] != NULL;  ++i)
                  continue;
            fakeenv = (char **) malloc((size_t) ((i + 2) *
                  sizeof *fakeenv));
            if (fakeenv == NULL ||
                  (fakeenv[0] = (char *) malloc(longest + 4)) == NULL) {
                              (void) perror(progname);
                              (void) exit(EXIT_FAILURE);
            }
            to = 0;
            (void) strcpy(fakeenv[to++], "TZ=");
            for (from = 0; environ[from] != NULL; ++from)
                  if (strncmp(environ[from], "TZ=", 3) != 0)
                        fakeenv[to++] = environ[from];
            fakeenv[to] = NULL;
            environ = fakeenv;
      }
      for (i = optind; i < argc; ++i) {
            static char buf[MAX_STRING_LENGTH];

            (void) strcpy(&fakeenv[0][3], argv[i]);
            if (!vflag) {
                  show(argv[i], now, FALSE);
                  continue;
            }
            /*
            ** Get lowest value of t.
            */
            t = hibit;
            if (t > 0)        /* time_t is unsigned */
                  t = 0;
            show(argv[i], t, TRUE);
            t += SECSPERHOUR * HOURSPERDAY;
            show(argv[i], t, TRUE);
            tm = *localtime(&t);
            (void) strncpy(buf, abbr(&tm), (sizeof buf) - 1);
            for ( ; ; ) {
                  if (cutoff != NULL && t >= cuttime)
                        break;
                  newt = t + SECSPERHOUR * 12;
                  if (cutoff != NULL && newt >= cuttime)
                        break;
                  if (newt <= t)
                        break;
                  newtm = *localtime(&newt);
                  if (delta(&newtm, &tm) != (newt - t) ||
                        newtm.tm_isdst != tm.tm_isdst ||
                        strcmp(abbr(&newtm), buf) != 0) {
                              newt = hunt(argv[i], t, newt);
                              newtm = *localtime(&newt);
                              (void) strncpy(buf, abbr(&newtm),
                                    (sizeof buf) - 1);
                  }
                  t = newt;
                  tm = newtm;
            }
            /*
            ** Get highest value of t.
            */
            t = ~((time_t) 0);
            if (t < 0)        /* time_t is signed */
                  t &= ~hibit;
            t -= SECSPERHOUR * HOURSPERDAY;
            show(argv[i], t, TRUE);
            t += SECSPERHOUR * HOURSPERDAY;
            show(argv[i], t, TRUE);
      }
      if (fflush(stdout) || ferror(stdout)) {
            (void) fprintf(stderr, "%s: ", argv[0]);
            (void) perror(_("Error writing standard output"));
            (void) exit(EXIT_FAILURE);
      }
      exit(EXIT_SUCCESS);

      /* gcc -Wall pacifier */
      for ( ; ; )
            continue;
}

static time_t
hunt(name, lot, hit)
char *      name;
time_t      lot;
time_t      hit;
{
      time_t            t;
      struct tm   lotm;
      struct tm   tm;
      static char loab[MAX_STRING_LENGTH];

      lotm = *localtime(&lot);
      (void) strncpy(loab, abbr(&lotm), (sizeof loab) - 1);
      while ((hit - lot) >= 2) {
            t = lot / 2 + hit / 2;
            if (t <= lot)
                  ++t;
            else if (t >= hit)
                  --t;
            tm = *localtime(&t);
            if (delta(&tm, &lotm) == (t - lot) &&
                  tm.tm_isdst == lotm.tm_isdst &&
                  strcmp(abbr(&tm), loab) == 0) {
                        lot = t;
                        lotm = tm;
            } else      hit = t;
      }
      show(name, lot, TRUE);
      show(name, hit, TRUE);
      return hit;
}

/*
** Thanks to Paul Eggert (eggert@twinsun.com) for logic used in delta.
*/

static long
delta(newp, oldp)
struct tm * newp;
struct tm * oldp;
{
      long  result;
      int   tmy;

      if (newp->tm_year < oldp->tm_year)
            return -delta(oldp, newp);
      result = 0;
      for (tmy = oldp->tm_year; tmy < newp->tm_year; ++tmy)
            result += DAYSPERNYEAR + isleap(tmy + TM_YEAR_BASE);
      result += newp->tm_yday - oldp->tm_yday;
      result *= HOURSPERDAY;
      result += newp->tm_hour - oldp->tm_hour;
      result *= MINSPERHOUR;
      result += newp->tm_min - oldp->tm_min;
      result *= SECSPERMIN;
      result += newp->tm_sec - oldp->tm_sec;
      return result;
}

static void
show(zone, t, v)
char *      zone;
time_t      t;
int   v;
{
      struct tm * tmp;

      (void) printf("%-*s  ", (int) longest, zone);
      if (v)
            (void) printf("%.24s UTC = ", asctime(gmtime(&t)));
      tmp = localtime(&t);
      (void) printf("%.24s", asctime(tmp));
      if (*abbr(tmp) != '\0')
            (void) printf(" %s", abbr(tmp));
      if (v) {
            (void) printf(" isdst=%d", tmp->tm_isdst);
#ifdef TM_GMTOFF
            (void) printf(" gmtoff=%ld", tmp->TM_GMTOFF);
#endif /* defined TM_GMTOFF */
      }
      (void) printf("\n");
}

static char *
abbr(tmp)
struct tm * tmp;
{
      register char *   result;
      static char nada;

      if (tmp->tm_isdst != 0 && tmp->tm_isdst != 1)
            return &nada;
      result = tzname[tmp->tm_isdst];
      return (result == NULL) ? &nada : result;
}

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