timezone.c

压缩解压,是unzip540的升级,这个外国网站摘来的源码,是evb编写.

    stdlen = name - stdname;
    if (stdlen < 3)
        return -1;
    if (*name == '\0')
        return -1;
    name = getoffset(name, &stdoffset);
    if (name == NULL)
        return -1;
    if (*name != '\0') {
        dstname = name;
        name = getzname(name);
        dstlen = name - dstname;    /* length of DST zone name */
        if (dstlen < 3)
            return -1;
        if (*name != '\0' && *name != ',' && *name != ';') {
            name = getoffset(name, &dstoffset);
            if (name == NULL)
                return -1;
        } else
            dstoffset = stdoffset - SECSPERHOUR;
        if (*name == '\0')
            name = TZDEFRULESTRING;
        if (*name == ',' || *name == ';') {
            struct rule     start;
            struct rule     end;

            ++name;
            if ((name = getrule(name, &start)) == NULL)
                return -1;
            if (*name++ != ',')
                return -1;
            if ((name = getrule(name, &end)) == NULL)
                return -1;
            if (*name != '\0')
                return -1;
            sp->typecnt = 2;    /* standard time and DST */
            sp->ttis[0].tt_gmtoff = -stdoffset;
            sp->ttis[0].tt_isdst = 0;
            sp->ttis[0].tt_abbrind = 0;
            sp->ttis[1].tt_gmtoff = -dstoffset;
            sp->ttis[1].tt_isdst = 1;
            sp->ttis[1].tt_abbrind = stdlen + 1;
            generate_transitions(sp, &start, &end);
        }
    } else {
        dstlen = 0;
        sp->typecnt = 1;        /* only standard time */
        sp->timecnt = 0;
        sp->ttis[0].tt_gmtoff = -stdoffset;
        sp->ttis[0].tt_isdst = 0;
        sp->ttis[0].tt_abbrind = 0;
    }
    sp->charcnt = stdlen + 1;
    if (dstlen != 0)
        sp->charcnt += dstlen + 1;
    if ((size_t) sp->charcnt > sizeof(sp->chars))
        return -1;
    cp = sp->chars;
    (void) strncpy(cp, stdname, stdlen);
    cp += stdlen;
    *cp++ = '\0';
    if (dstlen != 0) {
        (void) strncpy(cp, dstname, dstlen);
        *(cp + dstlen) = '\0';
    }
    return 0;
}

void tzset()
{
    char *TZstring;
    int dstfirst;
    static char *old_TZstring = NULL;

    TZstring = getenv("TZ");    /* read TZ envvar */
    if (old_TZstring && TZstring && !strcmp(old_TZstring, TZstring))
        /* do not repeatedly parse an unchanged TZ specification */
        return;
    if ((TZstring && TZstring[0] && Parse_TZ(TZstring, &statism) == 0)
                || IZTZ_GETLOCALETZINFO(&statism, generate_transitions)
                || Parse_TZ(gmt, &statism) == 0) {
        daylight  = statism.typecnt > 1;
        dstfirst  = daylight && statism.ttis[0].tt_isdst && !statism.ttis[1].tt_isdst;
        timezone  = -statism.ttis[dstfirst].tt_gmtoff;
        tzname[0] = statism.chars + statism.ttis[dstfirst].tt_abbrind;
        tzname[1] = statism.chars + statism.ttis[!dstfirst].tt_abbrind;
        real_timezone_is_set = TRUE;
        if (TZstring) {
            if (old_TZstring)
                old_TZstring = realloc(old_TZstring, strlen(TZstring) + 1);
            else
                old_TZstring = malloc(strlen(TZstring) + 1);
            if (old_TZstring)
                strcpy(old_TZstring, TZstring);
        }
    } else {
        timezone = 0;   /* default is GMT0 which means no offsets */
        daylight = 0;   /* from local system time                 */
        real_timezone_is_set = FALSE;
        if (old_TZstring) {
            free(old_TZstring);
            old_TZstring = NULL;
        }
    }
#ifdef IZTZ_SETLOCALTZINFO
    /* Some SAS/C library functions, e.g. stat(), call library       */
    /* __tzset() themselves. So envvar TZ *must* exist in order to   */
    /* to get the right offset from GMT.  XXX  TRY HARD to fix this! */
    set_TZ(timezone, daylight);
#endif /* IZTZ_SETLOCALTZINFO */
}

/* XXX  Does this also help SAS/C library work? */
void __tzset()
{
    if (!real_timezone_is_set) tzset();
}

static struct tm _tmbuf;

struct tm *gmtime(when)
     ZCONST time_t *when;
{
    long days = *when / SECSPERDAY;
    long secs = *when % SECSPERDAY;
    int isleap;

    memset(&_tmbuf, 0, sizeof(_tmbuf));   /* get any nonstandard fields */
    _tmbuf.tm_wday = (days + EPOCH_WDAY) % 7;
    _tmbuf.tm_year = EPOCH_YEAR - TM_YEAR_BASE;
    isleap = leap(_tmbuf.tm_year + TM_YEAR_BASE);
    while (days >= year_lengths[isleap]) {
        days -= year_lengths[isleap];
        _tmbuf.tm_year++;
        isleap = leap(_tmbuf.tm_year + TM_YEAR_BASE);
    }
    _tmbuf.tm_mon = 0;
    _tmbuf.tm_yday = days;
    while (days >= mon_lengths[isleap][_tmbuf.tm_mon])
        days -= mon_lengths[isleap][_tmbuf.tm_mon++];
    _tmbuf.tm_mday = days + 1;
    _tmbuf.tm_isdst = 0;
    _tmbuf.tm_sec = secs % SECSPERMIN;
    _tmbuf.tm_min = (secs / SECSPERMIN) % SECSPERMIN;
    _tmbuf.tm_hour = secs / SECSPERHOUR;
    return &_tmbuf;
}

struct tm *localtime(when)
     ZCONST time_t *when;
{
    time_t     localwhen = *when;
    int        timetype;
    struct tm *ret;

    __tzset();
    if (statism.timecnt == 0 || localwhen < statism.ats[0])
        timetype = statism.ttis[0].tt_isdst && statism.typecnt > 1 &&
                   !statism.ttis[1].tt_isdst;
    else {
        for (timetype = 1; timetype < statism.timecnt; ++timetype)
            if (localwhen < statism.ats[timetype])
                break;
        timetype = statism.types[timetype - 1];
    }
    localwhen += statism.ttis[timetype].tt_gmtoff;
    ret = gmtime(&localwhen);
    ret->tm_isdst = statism.ttis[timetype].tt_isdst;
    return ret;
}

#ifdef NEED__ISINDST
int _isindst(tb)
    struct tm *tb;
{
    time_t     localt;          /* time_t equivalent of given tm struct */
    time_t     univt;           /* assumed UTC value of given time */
    long       tzoffset_adj;    /* timezone-adjustment `remainder' */
    int        bailout_cnt;     /* counter of tries for tz correction */
    int        timetype;

    __tzset();

    /* when DST is unsupported in current timezone, DST is always off */
    if (statism.typecnt <= 1) return FALSE;

    localt = mkgmtime(tb);
    if (localt == (time_t)-1)
        /* specified time is out-of-range, default to FALSE */
        return FALSE;

    univt = localt - statism.ttis[0].tt_gmtoff;
    bailout_cnt = 3;
    do {
        if (statism.timecnt == 0 || univt < statism.ats[0])
            timetype = statism.ttis[0].tt_isdst && statism.typecnt > 1 &&
                       !statism.ttis[1].tt_isdst;
        else {
            for (timetype = 1; timetype < statism.timecnt; ++timetype)
                if (univt < statism.ats[timetype])
                    break;
            timetype = statism.types[timetype - 1];
        }
        if ((tzoffset_adj = localt - univt - statism.ttis[timetype].tt_gmtoff)
            == 0L)
            break;
        univt += tzoffset_adj;
    } while (--bailout_cnt > 0);

    /* return TRUE when DST is active at given time */
    return (statism.ttis[timetype].tt_isdst);
}
#endif /* NEED__ISINDST */
#endif /* !IZ_MKTIME_ONLY */

/* Return the equivalent in seconds past 12:00:00 a.m. Jan 1, 1970 GMT
   of the local time and date in the exploded time structure `tm',
   adjust out of range fields in `tm' and set `tm->tm_yday', `tm->tm_wday'.
   If `tm->tm_isdst < 0' was passed to mktime(), the correct setting of
   tm_isdst is determined and returned. Otherwise, mktime() assumes this
   field as valid; its information is used when converting local time
   to UTC.
   Return -1 if time in `tm' cannot be represented as time_t value. */

time_t mktime(tm)
     struct tm *tm;
{
  struct tm *ltm;               /* Local time. */
  time_t loctime;               /* The time_t value of local time. */
  time_t then;                  /* The time to return. */
  long tzoffset_adj;            /* timezone-adjustment `remainder' */
  int bailout_cnt;              /* counter of tries for tz correction */
  int save_isdst;               /* Copy of the tm->isdst input value */

  save_isdst = tm->tm_isdst;
  loctime = mkgmtime(tm);
  if (loctime == -1) {
    tm->tm_isdst = save_isdst;
    return (time_t)-1;
  }

  /* Correct for the timezone and any daylight savings time.
     The correction is verified and repeated when not correct, to
     take into account the rare case that a change to or from daylight
     savings time occurs between when it is the time in `tm' locally
     and when it is that time in Greenwich. After the second correction,
     the "timezone & daylight" offset should be correct in all cases. To
     be sure, we allow a third try, but then the loop is stopped. */
  bailout_cnt = 3;
  then = loctime;
  do {
    ltm = localtime(&then);
    if (ltm == (struct tm *)NULL ||
        (tzoffset_adj = loctime - mkgmtime(ltm)) == 0L)
      break;
    then += tzoffset_adj;
  } while (--bailout_cnt > 0);

  if (ltm == (struct tm *)NULL || tzoffset_adj != 0L) {
    /* Signal failure if timezone adjustment did not converge. */
    tm->tm_isdst = save_isdst;
    return (time_t)-1;
  }

  if (save_isdst >= 0) {
    if (ltm->tm_isdst  && !save_isdst)
    {
      if (then + 3600 < then)
        then = (time_t)-1;
      else
        then += 3600;
    }
    else if (!ltm->tm_isdst && save_isdst)
    {
      if (then - 3600 > then)
        then = (time_t)-1;
      else
        then -= 3600;
    }
    ltm->tm_isdst = save_isdst;
  }

  if (tm != ltm)  /* `tm' may already point to localtime's internal storage */
    *tm = *ltm;

  return then;
}


#ifndef NO_TIME_T_MAX
   /* Provide default values for the upper limit of the time_t range.
      These are the result of the decomposition into a `struct tm' for
      the time value 0xFFFFFFFEL ( = (time_t)-2 ).
      Note: `(time_t)-1' is reserved for "invalid time"!  */
#  ifndef TM_YEAR_MAX
#    define TM_YEAR_MAX         2106
#  endif
#  ifndef TM_MON_MAX
#    define TM_MON_MAX          1       /* February */
#  endif
#  ifndef TM_MDAY_MAX
#    define TM_MDAY_MAX         7
#  endif
#  ifndef TM_HOUR_MAX
#    define TM_HOUR_MAX         6
#  endif
#  ifndef TM_MIN_MAX
#    define TM_MIN_MAX          28
#  endif
#  ifndef TM_SEC_MAX
#    define TM_SEC_MAX          14
#  endif
#endif /* NO_TIME_T_MAX */

/* Adjusts out-of-range values for `tm' field `tm_member'. */
#define ADJUST_TM(tm_member, tm_carry, modulus) \
  if ((tm_member) < 0) { \
    tm_carry -= (1 - ((tm_member)+1) / (modulus)); \
    tm_member = (modulus-1) + (((tm_member)+1) % (modulus)); \
  } else if ((tm_member) >= (modulus)) { \
    tm_carry += (tm_member) / (modulus); \
    tm_member = (tm_member) % (modulus); \
  }

/* Return the equivalent in seconds past 12:00:00 a.m. Jan 1, 1970 GMT
   of the Greenwich Mean time and date in the exploded time structure `tm'.
   This function does always put back normalized values into the `tm' struct,
   parameter, including the calculated numbers for `tm->tm_yday',
   `tm->tm_wday', and `tm->tm_isdst'.
   Returns -1 if the time in the `tm' parameter cannot be represented
   as valid `time_t' number. */

time_t mkgmtime(tm)
     struct tm *tm;
{
  int years, months, days, hours, minutes, seconds;

  years = tm->tm_year + TM_YEAR_BASE;   /* year - 1900 -> year */
  months = tm->tm_mon;                  /* 0..11 */
  days = tm->tm_mday - 1;               /* 1..31 -> 0..30 */
  hours = tm->tm_hour;                  /* 0..23 */
  minutes = tm->tm_min;                 /* 0..59 */
  seconds = tm->tm_sec;                 /* 0..61 in ANSI C. */

  ADJUST_TM(seconds, minutes, 60)
  ADJUST_TM(minutes, hours, 60)
  ADJUST_TM(hours, days, 24)
  ADJUST_TM(months, years, 12)
  if (days < 0)
    do {
      if (--months < 0) {
        --years;
        months = 11;
      }
      days += monthlen(months, years);
    } while (days < 0);
  else
    while (days >= monthlen(months, years)) {
      days -= monthlen(months, years);
      if (++months >= 12) {
        ++years;
        months = 0;
      }
    }

  /* Restore adjusted values in tm structure */
  tm->tm_year = years - TM_YEAR_BASE;
  tm->tm_mon = months;
  tm->tm_mday = days + 1;
  tm->tm_hour = hours;
  tm->tm_min = minutes;
  tm->tm_sec = seconds;

  /* Set `days' to the number of days into the year. */
  days += YDAYS(months, years);
  tm->tm_yday = days;

  /* Now calculate `days' to the number of days since Jan 1, 1970. */
  days = (unsigned)days + 365 * (unsigned)(years - EPOCH_YEAR) +
         (unsigned)(nleap (years));
  tm->tm_wday = ((unsigned)days + EPOCH_WDAY) % 7;
  tm->tm_isdst = 0;

  if (years < EPOCH_YEAR)
    return (time_t)-1;

#if (defined(TM_YEAR_MAX) && defined(TM_MON_MAX) && defined(TM_MDAY_MAX))
#if (defined(TM_HOUR_MAX) && defined(TM_MIN_MAX) && defined(TM_SEC_MAX))
  if (years > TM_YEAR_MAX ||
      (years == TM_YEAR_MAX &&
       (tm->tm_yday > (YDAYS(TM_MON_MAX, TM_YEAR_MAX) + (TM_MDAY_MAX - 1)) ||
        (tm->tm_yday == (YDAYS(TM_MON_MAX, TM_YEAR_MAX) + (TM_MDAY_MAX - 1)) &&
         (hours > TM_HOUR_MAX ||
          (hours == TM_HOUR_MAX &&
           (minutes > TM_MIN_MAX ||
            (minutes == TM_MIN_MAX && seconds > TM_SEC_MAX) )))))))
    return (time_t)-1;
#endif
#endif

  return (time_t)(SECSPERDAY * (unsigned long)(unsigned)days +
                  SECSPERHOUR * (unsigned long)hours +
                  (unsigned long)(SECSPERMIN * minutes + seconds));
}

#endif /* __timezone_c */