make Local channel return sensible device state values

[asterisk-bristuff.git] / stdtime / localtime.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * Most of this code is in the public domain, so clarified as of
 * June 5, 1996 by Arthur David Olson (arthur_david_olson@nih.gov).
 *
 * All modifications to this code to abstract timezones away from
 * the environment are by Tilghman Lesher, <tlesher@vcch.com>, with
 * the copyright assigned to Digium.
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * Multi-timezone Localtime code
 * 
 * \author Leap second handling Bradley White (bww@k.gp.cs.cmu.edu).
 * \author POSIX-style TZ environment variable handling from Guy Harris (guy@auspex.com).
 *
 */

/*
 * Asterisk defines
 *
 * Don't mess with these unless you're really sure you know what you're doing.
 */
#ifndef _THREAD_SAFE
#define _THREAD_SAFE
#endif
#define TZ_STRLEN_MAX   255
/* #define DEBUG */

#include "asterisk.h"
 
ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

/*LINTLIBRARY*/

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#ifdef DEBUG
#include <stdio.h>
#endif

#include "private.h"
#include "tzfile.h"
#include "asterisk/lock.h"
#include "asterisk/localtime.h"


#ifndef lint
#ifndef NOID
static const char elsieid[] = "@(#)localtime.c  7.57";
#endif /* !defined NOID */
#endif /* !defined lint */



/*
** SunOS 4.1.1 headers lack O_BINARY.
*/

#ifdef O_BINARY
#define OPEN_MODE       (O_RDONLY | O_BINARY)
#endif /* defined O_BINARY */
#ifndef O_BINARY
#define OPEN_MODE       O_RDONLY
#endif /* !defined O_BINARY */

#ifdef SOLARIS
#undef TM_ZONE
#undef TM_GMTOFF 
#endif

#ifdef TM_ZONE
#ifndef WILDABBR
/*! \note
 * Someone might make incorrect use of a time zone abbreviation:
 *      1.      They might reference tzname[0] before calling ast_tzset (explicitly
 *              or implicitly).
 *      2.      They might reference tzname[1] before calling ast_tzset (explicitly
 *              or implicitly).
 *      3.      They might reference tzname[1] after setting to a time zone
 *              in which Daylight Saving Time is never observed.
 *      4.      They might reference tzname[0] after setting to a time zone
 *              in which Standard Time is never observed.
 *      5.      They might reference tm.TM_ZONE after calling offtime.
 * What's best to do in the above cases is open to debate;
 * for now, we just set things up so that in any of the five cases
 * WILDABBR is used.  Another possibility:  initialize tzname[0] to the
 * string "tzname[0] used before set", and similarly for the other cases.
 * And another:  initialize tzname[0] to "ERA", with an explanation in the
 * manual page of what this "time zone abbreviation" means (doing this so
 * that tzname[0] has the "normal" length of three characters).
 */
#define WILDABBR        "   "
#endif /* !defined WILDABBR */

static char             wildabbr[] = "WILDABBR";
#endif /* TM_ZONE */

/*! \brief FreeBSD defines 'zone' in 'struct tm' as non-const, so don't declare this
   string as const. */
static char             gmt[] = "GMT";

/*!< \brief time type information */
struct ttinfo {
        long            tt_gmtoff;      /*!< GMT offset in seconds */
        int             tt_isdst;       /*!< used to set tm_isdst */
        int             tt_abbrind;     /*!< abbreviation list index */
        int             tt_ttisstd;     /*!< TRUE if transition is std time */
        int             tt_ttisgmt;     /*!< TRUE if transition is GMT */
};

/*! \brief leap second information */
struct lsinfo {
        time_t          ls_trans;       /*!< transition time */
        long            ls_corr;        /*!< correction to apply */
};

#define BIGGEST(a, b)   (((a) > (b)) ? (a) : (b))

#ifdef TZNAME_MAX
#define MY_TZNAME_MAX   TZNAME_MAX
#endif /* defined TZNAME_MAX */
#ifndef TZNAME_MAX
#define MY_TZNAME_MAX   255
#endif /* !defined TZNAME_MAX */

struct state {
        char    name[TZ_STRLEN_MAX + 1];
        int             leapcnt;
        int             timecnt;
        int             typecnt;
        int             charcnt;
        time_t          ats[TZ_MAX_TIMES];
        unsigned char   types[TZ_MAX_TIMES];
        struct ttinfo   ttis[TZ_MAX_TYPES];
        char            chars[BIGGEST(BIGGEST(TZ_MAX_CHARS + 1, sizeof gmt),
                                (2 * (MY_TZNAME_MAX + 1)))];
        struct lsinfo   lsis[TZ_MAX_LEAPS];
        struct state    *next;
};

struct rule {
        int             r_type;         /*!< type of rule--see below */
        int             r_day;          /*!< day number of rule */
        int             r_week;         /*!< week number of rule */
        int             r_mon;          /*!< month number of rule */
        long            r_time;         /*!< transition time of rule */
};

#define JULIAN_DAY              0       /*!< Jn - Julian day */
#define DAY_OF_YEAR             1       /*!< n - day of year */
#define MONTH_NTH_DAY_OF_WEEK   2       /*!< Mm.n.d - month, week, day of week */

/*
** Prototypes for static functions.
*/

static long             detzcode P((const char * codep));
static const char *     getnum P((const char * strp, int * nump, int min,
                                int max));
static const char *     getsecs P((const char * strp, long * secsp));
static const char *     getoffset P((const char * strp, long * offsetp));
static const char *     getrule P((const char * strp, struct rule * rulep));
static void             gmtload P((struct state * sp));
static void             gmtsub P((const time_t * timep, long offset,
                                struct tm * tmp, const char * zone));
static void             localsub P((const time_t * timep, long offset,
                                struct tm * tmp, const char * zone));
static int              increment_overflow P((int * number, int delta));
static int              normalize_overflow P((int * tensptr, int * unitsptr,
                                int base));
static time_t           time1 P((struct tm * tmp,
                                void(*funcp) P((const time_t *,
                                long, struct tm *, const char*)),
                                long offset, const char * zone));
static time_t           time2 P((struct tm *tmp,
                                void(*funcp) P((const time_t *,
                                long, struct tm*, const char*)),
                                long offset, int * okayp, const char * zone));
static void             timesub P((const time_t * timep, long offset,
                                const struct state * sp, struct tm * tmp));
static int              tmcomp P((const struct tm * atmp,
                                const struct tm * btmp));
static time_t           transtime P((time_t janfirst, int year,
                                const struct rule * rulep, long offset));
static int              tzload P((const char * name, struct state * sp));
static int              tzparse P((const char * name, struct state * sp,
                                int lastditch));

static struct state *   lclptr      = NULL;
static struct state *   last_lclptr = NULL;
static struct state *   gmtptr      = NULL;

#ifndef TZ_STRLEN_MAX
#define TZ_STRLEN_MAX 255
#endif /* !defined TZ_STRLEN_MAX */

static int              gmt_is_set;
#ifdef  _THREAD_SAFE
AST_MUTEX_DEFINE_STATIC(lcl_mutex);
AST_MUTEX_DEFINE_STATIC(tzset_mutex);
AST_MUTEX_DEFINE_STATIC(tzsetwall_mutex);
AST_MUTEX_DEFINE_STATIC(gmt_mutex);
#endif

/*
** Section 4.12.3 of X3.159-1989 requires that
**      Except for the strftime function, these functions [asctime,
**      ctime, gmtime, localtime] return values in one of two static
**      objects: a broken-down time structure and an array of char.
** Thanks to Paul Eggert (eggert@twinsun.com) for noting this.
*/

static long detzcode(const char * const codep)
{
        register long   result;
        register int    i;

        result = (codep[0] & 0x80) ? ~0L : 0L;
        for (i = 0; i < 4; ++i)
                result = (result << 8) | (codep[i] & 0xff);
        return result;
}

static int tzload(register const char *name, register struct state *const       sp)
{
        register const char *   p;
        register int            i;
        register int            fid;

#ifdef DEBUG
        fprintf(stderr,"tzload called with name=%s, sp=%d\n", name, sp);
#endif
        if (name == NULL && (name = TZDEFAULT) == NULL)
                return -1;
        {
                register int    doaccess;
                struct stat     stab;
                /*
                ** Section 4.9.1 of the C standard says that
                ** "FILENAME_MAX expands to an integral constant expression
                ** that is the size needed for an array of char large enough
                ** to hold the longest file name string that the implementation
                ** guarantees can be opened."
                */
                char            fullname[FILENAME_MAX + 1] = "";

                if (name[0] == ':')
                        ++name;
                doaccess = name[0] == '/';
                if (!doaccess) {
                        if ((p = TZDIR) == NULL)
                                return -1;
                        if ((strlen(p) + 1 + strlen(name) + 1) >= sizeof fullname)
                                return -1;
                        (void) strncpy(fullname, p, sizeof(fullname) - 1);
                        (void) strncat(fullname, "/", sizeof(fullname) - strlen(fullname) - 1);
                        (void) strncat(fullname, name, sizeof(fullname) - strlen(fullname) - 1);
                        /*
                        ** Set doaccess if '.' (as in "../") shows up in name.
                        */
                        if (strchr(name, '.') != NULL)
                                doaccess = TRUE;
                        name = fullname;
                }
                if (doaccess && access(name, R_OK) != 0)
                        return -1;
                if ((fid = open(name, OPEN_MODE)) == -1)
                        return -1;
                if ((fstat(fid, &stab) < 0) || !S_ISREG(stab.st_mode)) {
                        close(fid);
                        return -1;
                }
        }
        {
                struct tzhead * tzhp;
                char            buf[sizeof *sp + sizeof *tzhp];
                int             ttisstdcnt;
                int             ttisgmtcnt;

                i = read(fid, buf, sizeof buf);
                if (close(fid) != 0)
                        return -1;
                p = buf;
                p += (sizeof tzhp->tzh_magic) + (sizeof tzhp->tzh_reserved);
                ttisstdcnt = (int) detzcode(p);
                p += 4;
                ttisgmtcnt = (int) detzcode(p);
                p += 4;
                sp->leapcnt = (int) detzcode(p);
                p += 4;
                sp->timecnt = (int) detzcode(p);
                p += 4;
                sp->typecnt = (int) detzcode(p);
                p += 4;
                sp->charcnt = (int) detzcode(p);
                p += 4;
                if (sp->leapcnt < 0 || sp->leapcnt > TZ_MAX_LEAPS ||
                        sp->typecnt <= 0 || sp->typecnt > TZ_MAX_TYPES ||
                        sp->timecnt < 0 || sp->timecnt > TZ_MAX_TIMES ||
                        sp->charcnt < 0 || sp->charcnt > TZ_MAX_CHARS ||
                        (ttisstdcnt != sp->typecnt && ttisstdcnt != 0) ||
                        (ttisgmtcnt != sp->typecnt && ttisgmtcnt != 0))
                                return -1;
                if (i - (p - buf) < sp->timecnt * 4 +   /* ats */
                        sp->timecnt +                   /* types */
                        sp->typecnt * (4 + 2) +         /* ttinfos */
                        sp->charcnt +                   /* chars */
                        sp->leapcnt * (4 + 4) +         /* lsinfos */
                        ttisstdcnt +                    /* ttisstds */
                        ttisgmtcnt)                     /* ttisgmts */
                                return -1;
                for (i = 0; i < sp->timecnt; ++i) {
                        sp->ats[i] = detzcode(p);
                        p += 4;
                }
                for (i = 0; i < sp->timecnt; ++i) {
                        sp->types[i] = (unsigned char) *p++;
                        if (sp->types[i] >= sp->typecnt)
                                return -1;
                }
                for (i = 0; i < sp->typecnt; ++i) {
                        register struct ttinfo *        ttisp;

                        ttisp = &sp->ttis[i];
                        ttisp->tt_gmtoff = detzcode(p);
                        p += 4;
                        ttisp->tt_isdst = (unsigned char) *p++;
                        if (ttisp->tt_isdst != 0 && ttisp->tt_isdst != 1)
                                return -1;
                        ttisp->tt_abbrind = (unsigned char) *p++;
                        if (ttisp->tt_abbrind < 0 ||
                                ttisp->tt_abbrind > sp->charcnt)
                                        return -1;
                }
                for (i = 0; i < sp->charcnt; ++i)
                        sp->chars[i] = *p++;
                sp->chars[i] = '\0';    /* ensure '\0' at end */
                for (i = 0; i < sp->leapcnt; ++i) {
                        register struct lsinfo *        lsisp;

                        lsisp = &sp->lsis[i];
                        lsisp->ls_trans = detzcode(p);
                        p += 4;
                        lsisp->ls_corr = detzcode(p);
                        p += 4;
                }
                for (i = 0; i < sp->typecnt; ++i) {
                        register struct ttinfo *        ttisp;

                        ttisp = &sp->ttis[i];
                        if (ttisstdcnt == 0)
                                ttisp->tt_ttisstd = FALSE;
                        else {
                                ttisp->tt_ttisstd = *p++;
                                if (ttisp->tt_ttisstd != TRUE &&
                                        ttisp->tt_ttisstd != FALSE)
                                                return -1;
                        }
                }
                for (i = 0; i < sp->typecnt; ++i) {
                        register struct ttinfo *        ttisp;

                        ttisp = &sp->ttis[i];
                        if (ttisgmtcnt == 0)
                                ttisp->tt_ttisgmt = FALSE;
                        else {
                                ttisp->tt_ttisgmt = *p++;
                                if (ttisp->tt_ttisgmt != TRUE &&
                                        ttisp->tt_ttisgmt != FALSE)
                                                return -1;
                        }
                }
        }
        return 0;
}

static const int        mon_lengths[2][MONSPERYEAR] = {
        { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
        { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
};

static const int        year_lengths[2] = {
        DAYSPERNYEAR, DAYSPERLYEAR
};

/*! \brief
 * Given a pointer into a time zone string, extract a number from that string.
 * \return Check that the number is within a specified range; if it is not, return
 * NULL.
 * Otherwise, return a pointer to the first character not part of the number.
*/

static const char *getnum(register const char *strp, int * const nump, const int min, const int max)
{
        register char   c;
        register int    num;

        if (strp == NULL || !is_digit(c = *strp))
                return NULL;
        num = 0;
        do {
                num = num * 10 + (c - '0');
                if (num > max)
                        return NULL;    /* illegal value */
                c = *++strp;
        } while (is_digit(c));
        if (num < min)
                return NULL;            /* illegal value */
        *nump = num;
        return strp;
}

/*! \brief
 * Given a pointer into a time zone string, extract a number of seconds,
 * in hh[:mm[:ss]] form, from the string.
 * \return If any error occurs, return NULL.
 * Otherwise, return a pointer to the first character not part of the number
 * of seconds.
*/

static const char *getsecs(register const char *strp, long * const secsp)
{
        int     num;

        /*
        ** `HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like
        ** "M10.4.6/26", which does not conform to Posix,
        ** but which specifies the equivalent of
        ** ``02:00 on the first Sunday on or after 23 Oct''.
        */
        strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1);
        if (strp == NULL)
                return NULL;
        *secsp = num * (long) SECSPERHOUR;
        if (*strp == ':') {
                ++strp;
                strp = getnum(strp, &num, 0, MINSPERHOUR - 1);
                if (strp == NULL)
                        return NULL;
                *secsp += num * SECSPERMIN;
                if (*strp == ':') {
                        ++strp;
                        /* `SECSPERMIN' allows for leap seconds.  */
                        strp = getnum(strp, &num, 0, SECSPERMIN);
                        if (strp == NULL)
                                return NULL;
                        *secsp += num;
                }
        }
        return strp;
}

/*! \brief
 * Given a pointer into a time zone string, extract an offset, in
 * [+-]hh[:mm[:ss]] form, from the string.
 * \return If any error occurs, return NULL.
 * Otherwise, return a pointer to the first character not part of the time.
*/

static const char * getoffset(register const char *strp, long * const offsetp)
{
        register int    neg = 0;

        if (*strp == '-') {
                neg = 1;
                ++strp;
        } else if (*strp == '+')
                ++strp;
        strp = getsecs(strp, offsetp);
        if (strp == NULL)
                return NULL;            /* illegal time */
        if (neg)
                *offsetp = -*offsetp;
        return strp;
}

/*! \brief
 * Given a pointer into a time zone string, extract a rule in the form
 * date[/time].  See POSIX section 8 for the format of "date" and "time".
 * \return If a valid rule is not found, return NULL.
 * Otherwise, return a pointer to the first character not part of the rule.
*/

static const char *getrule(const char *strp, register struct rule * const rulep)
{
        if (*strp == 'J') {
                /*
                ** Julian day.
                */
                rulep->r_type = JULIAN_DAY;
                ++strp;
                strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR);
        } else if (*strp == 'M') {
                /*
                ** Month, week, day.
                */
                rulep->r_type = MONTH_NTH_DAY_OF_WEEK;
                ++strp;
                strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR);
                if (strp == NULL)
                        return NULL;
                if (*strp++ != '.')
                        return NULL;
                strp = getnum(strp, &rulep->r_week, 1, 5);
                if (strp == NULL)
                        return NULL;
                if (*strp++ != '.')
                        return NULL;
                strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1);
        } else if (is_digit(*strp)) {
                /*
                ** Day of year.
                */
                rulep->r_type = DAY_OF_YEAR;
                strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);
        } else  return NULL;            /* invalid format */
        if (strp == NULL)
                return NULL;
        if (*strp == '/') {
                /*
                ** Time specified.
                */
                ++strp;
                strp = getsecs(strp, &rulep->r_time);
        } else  rulep->r_time = 2 * SECSPERHOUR;        /* default = 2:00:00 */
        return strp;
}

/*! \brief
 * Given the Epoch-relative time of January 1, 00:00:00 GMT, in a year, the
 * year, a rule, and the offset from GMT at the time that rule takes effect,
 * calculate the Epoch-relative time that rule takes effect.
*/

static time_t transtime(janfirst, year, rulep, offset)
const time_t                            janfirst;
const int                               year;
register const struct rule * const      rulep;
const long                              offset;
{
        register int    leapyear;
        register time_t value = 0;
        register int    i;
        int             d, m1, yy0, yy1, yy2, dow;

        leapyear = isleap(year);
        switch (rulep->r_type) {

        case JULIAN_DAY:
                /*
                ** Jn - Julian day, 1 == January 1, 60 == March 1 even in leap
                ** years.
                ** In non-leap years, or if the day number is 59 or less, just
                ** add SECSPERDAY times the day number-1 to the time of
                ** January 1, midnight, to get the day.
                */
                value = janfirst + (rulep->r_day - 1) * SECSPERDAY;
                if (leapyear && rulep->r_day >= 60)
                        value += SECSPERDAY;
                break;

        case DAY_OF_YEAR:
                /*
                ** n - day of year.
                ** Just add SECSPERDAY times the day number to the time of
                ** January 1, midnight, to get the day.
                */
                value = janfirst + rulep->r_day * SECSPERDAY;
                break;

        case MONTH_NTH_DAY_OF_WEEK:
                /*
                ** Mm.n.d - nth "dth day" of month m.
                */
                value = janfirst;
                for (i = 0; i < rulep->r_mon - 1; ++i)
                        value += mon_lengths[leapyear][i] * SECSPERDAY;

                /*
                ** Use Zeller's Congruence to get day-of-week of first day of
                ** month.
                */
                m1 = (rulep->r_mon + 9) % 12 + 1;
                yy0 = (rulep->r_mon <= 2) ? (year - 1) : year;
                yy1 = yy0 / 100;
                yy2 = yy0 % 100;
                dow = ((26 * m1 - 2) / 10 +
                        1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
                if (dow < 0)
                        dow += DAYSPERWEEK;

                /*
                ** "dow" is the day-of-week of the first day of the month.  Get
                ** the day-of-month (zero-origin) of the first "dow" day of the
                ** month.
                */
                d = rulep->r_day - dow;
                if (d < 0)
                        d += DAYSPERWEEK;
                for (i = 1; i < rulep->r_week; ++i) {
                        if (d + DAYSPERWEEK >=
                                mon_lengths[leapyear][rulep->r_mon - 1])
                                        break;
                        d += DAYSPERWEEK;
                }

                /*
                ** "d" is the day-of-month (zero-origin) of the day we want.
                */
                value += d * SECSPERDAY;
                break;
        }

        /*
        ** "value" is the Epoch-relative time of 00:00:00 GMT on the day in
        ** question.  To get the Epoch-relative time of the specified local
        ** time on that day, add the transition time and the current offset
        ** from GMT.
        */
        return value + rulep->r_time + offset;
}

/*
** Given a POSIX section 8-style TZ string, fill in the rule tables as
** appropriate.
*/

static int
tzparse(name, sp, lastditch)
const char *                    name;
register struct state * const   sp;
const int                       lastditch;
{
        const char *                    stdname;
        const char *                    dstname = NULL;
        size_t                          stdlen = 0;
        size_t                          dstlen = 0;
        long                            stdoffset = 0L;
        long                            dstoffset = 0L;
        register time_t *               atp;
        register unsigned char *        typep;
        register char *                 cp;
        register int                    load_result;

        stdname = name;
#ifdef DEBUG
        fprintf(stderr, "tzparse(): loading default rules\n");
#endif
        load_result = tzload(TZDEFRULES, sp);
        if (load_result != 0)
                sp->leapcnt = 0;                /* so, we're off a little */
        if (*name != '\0') {
                if (*name != '\0' && *name != ',' && *name != ';') {
                        name = getoffset(name, &dstoffset);
                        if (name == NULL)
                                return -1;
                } else  dstoffset = stdoffset - SECSPERHOUR;
                if (*name == ',' || *name == ';') {
                        struct rule     start;
                        struct rule     end;
                        register int    year;
                        register time_t janfirst;
                        time_t          starttime;
                        time_t          endtime;

                        ++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 */
                        /*
                        ** Two transitions per year, from EPOCH_YEAR to 2037.
                        */
                        sp->timecnt = 2 * (2037 - EPOCH_YEAR + 1);
                        if (sp->timecnt > TZ_MAX_TIMES)
                                return -1;
                        sp->ttis[0].tt_gmtoff = -dstoffset;
                        sp->ttis[0].tt_isdst = 1;
                        sp->ttis[0].tt_abbrind = stdlen + 1;
                        sp->ttis[1].tt_gmtoff = -stdoffset;
                        sp->ttis[1].tt_isdst = 0;
                        sp->ttis[1].tt_abbrind = 0;
                        atp = sp->ats;
                        typep = sp->types;
                        janfirst = 0;
                        for (year = EPOCH_YEAR; year <= 2037; ++year) {
                                starttime = transtime(janfirst, year, &start,
                                        stdoffset);
                                endtime = transtime(janfirst, year, &end,
                                        dstoffset);
                                if (starttime > endtime) {
                                        *atp++ = endtime;
                                        *typep++ = 1;   /* DST ends */
                                        *atp++ = starttime;
                                        *typep++ = 0;   /* DST begins */
                                } else {
                                        *atp++ = starttime;
                                        *typep++ = 0;   /* DST begins */
                                        *atp++ = endtime;
                                        *typep++ = 1;   /* DST ends */
                                }
                                janfirst += year_lengths[isleap(year)] *
                                        SECSPERDAY;
                        }
                } else {
                        register long   theirstdoffset;
                        register long   theirdstoffset;
                        register long   theiroffset;
                        register int    isdst;
                        register int    i;
                        register int    j;

                        if (*name != '\0')
                                return -1;
                        if (load_result != 0)
                                return -1;
                        /*
                        ** Initial values of theirstdoffset and theirdstoffset.
                        */
                        theirstdoffset = 0;
                        for (i = 0; i < sp->timecnt; ++i) {
                                j = sp->types[i];
                                if (!sp->ttis[j].tt_isdst) {
                                        theirstdoffset =
                                                -sp->ttis[j].tt_gmtoff;
                                        break;
                                }
                        }
                        theirdstoffset = 0;
                        for (i = 0; i < sp->timecnt; ++i) {
                                j = sp->types[i];
                                if (sp->ttis[j].tt_isdst) {
                                        theirdstoffset =
                                                -sp->ttis[j].tt_gmtoff;
                                        break;
                                }
                        }
                        /*
                        ** Initially we're assumed to be in standard time.
                        */
                        isdst = FALSE;
                        theiroffset = theirstdoffset;
                        /*
                        ** Now juggle transition times and types
                        ** tracking offsets as you do.
                        */
                        for (i = 0; i < sp->timecnt; ++i) {
                                j = sp->types[i];
                                sp->types[i] = sp->ttis[j].tt_isdst;
                                if (sp->ttis[j].tt_ttisgmt) {
                                        /* No adjustment to transition time */
                                } else {
                                        /*
                                        ** If summer time is in effect, and the
                                        ** transition time was not specified as
                                        ** standard time, add the summer time
                                        ** offset to the transition time;
                                        ** otherwise, add the standard time
                                        ** offset to the transition time.
                                        */
                                        /*
                                        ** Transitions from DST to DDST
                                        ** will effectively disappear since
                                        ** POSIX provides for only one DST
                                        ** offset.
                                        */
                                        if (isdst && !sp->ttis[j].tt_ttisstd) {
                                                sp->ats[i] += dstoffset -
                                                        theirdstoffset;
                                        } else {
                                                sp->ats[i] += stdoffset -
                                                        theirstdoffset;
                                        }
                                }
                                theiroffset = -sp->ttis[j].tt_gmtoff;
                                if (sp->ttis[j].tt_isdst)
                                        theirdstoffset = theiroffset;
                                else    theirstdoffset = theiroffset;
                        }
                        /*
                        ** Finally, fill in ttis.
                        ** ttisstd and ttisgmt need not be handled.
                        */
                        sp->ttis[0].tt_gmtoff = -stdoffset;
                        sp->ttis[0].tt_isdst = FALSE;
                        sp->ttis[0].tt_abbrind = 0;
                        sp->ttis[1].tt_gmtoff = -dstoffset;
                        sp->ttis[1].tt_isdst = TRUE;
                        sp->ttis[1].tt_abbrind = stdlen + 1;
                }
        } 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 (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;
}

static void
gmtload(sp)
struct state * const    sp;
{
        if (tzload(gmt, sp) != 0)
                (void) tzparse(gmt, sp, TRUE);
}

/*
** A non-static declaration of ast_tzsetwall in a system header file
** may cause a warning about this upcoming static declaration...
*/
static
#ifdef  _THREAD_SAFE
int
ast_tzsetwall_basic P((void))
#else
int
ast_tzsetwall P((void))
#endif
{
        struct state *cur_state = lclptr;

        /* Find the appropriate structure, if already parsed */
        while (cur_state != NULL) {
                if (cur_state->name[0] == '\0')
                        break;
                cur_state = cur_state->next;
        }
        if (cur_state != NULL)
                return 0;
        cur_state = malloc(sizeof(struct state));
        if (cur_state == NULL) {
                return -1;
        }
        memset(cur_state,0,sizeof(struct state));
        if (tzload((char *) NULL, cur_state) != 0)
#ifdef DEBUG
        {
                fprintf(stderr, "ast_tzsetwall: calling gmtload()\n");
#endif
                gmtload(cur_state);
#ifdef DEBUG
        }
#endif

        if (last_lclptr)
                last_lclptr->next = cur_state;
        else
                lclptr = cur_state;
        last_lclptr = cur_state;
        return 0;
}

#ifdef  _THREAD_SAFE
int
ast_tzsetwall P((void))
{
        ast_mutex_lock(&tzsetwall_mutex);
        ast_tzsetwall_basic();
        ast_mutex_unlock(&tzsetwall_mutex);
        return 0;
}
#endif

#ifdef  _THREAD_SAFE
static int
ast_tzset_basic P((const char *name))
#else
int
ast_tzset P((const char *name))
#endif
{
        struct state *cur_state = lclptr;

        /* Not set at all */
        if (name == NULL) {
                return ast_tzsetwall();
        }

        /* Find the appropriate structure, if already parsed */
        while (cur_state != NULL) {
                if (!strcmp(cur_state->name,name))
                        break;
                cur_state = cur_state->next;
        }
        if (cur_state != NULL)
                return 0;

        cur_state = malloc(sizeof(struct state));
        if (cur_state == NULL) {
                return -1;
        }
        memset(cur_state,0,sizeof(*cur_state));

        /* Name is set, but set to the empty string == no adjustments */
        if (name[0] == '\0') {
                /*
                ** User wants it fast rather than right.
                */
                cur_state->leapcnt = 0;         /* so, we're off a little */
                cur_state->timecnt = 0;
                cur_state->ttis[0].tt_gmtoff = 0;
                cur_state->ttis[0].tt_abbrind = 0;
                (void) strncpy(cur_state->chars, gmt, sizeof(cur_state->chars) - 1);
        } else if (tzload(name, cur_state) != 0) {
                if (name[0] == ':') {
                        (void) gmtload(cur_state);
                } else if (tzparse(name, cur_state, FALSE) != 0) {
                        /* If not found, load localtime */
                        if (tzload("/etc/localtime", cur_state) != 0)
                                /* Last ditch, get GMT */
                                (void) gmtload(cur_state);
                }
        }
        strncpy(cur_state->name, name, sizeof(cur_state->name) - 1);
        if (last_lclptr)
                last_lclptr->next = cur_state;
        else
                lclptr = cur_state;
        last_lclptr = cur_state;
        return 0;
}

#ifdef  _THREAD_SAFE
void
ast_tzset P((const char *name))
{
        ast_mutex_lock(&tzset_mutex);
        ast_tzset_basic(name);
        ast_mutex_unlock(&tzset_mutex);
}
#endif

/*
** The easy way to behave "as if no library function calls" localtime
** is to not call it--so we drop its guts into "localsub", which can be
** freely called.  (And no, the PANS doesn't require the above behavior--
** but it *is* desirable.)
**
** The unused offset argument is for the benefit of mktime variants.
*/

/*ARGSUSED*/
static void
localsub(timep, offset, tmp, zone)
const time_t * const    timep;
const long              offset;
struct tm * const       tmp;
const char * const      zone;
{
        register struct state *         sp;
        register const struct ttinfo *  ttisp;
        register int                    i;
        const time_t                    t = *timep;

        sp = lclptr;
        /* Find the right zone record */
        if (zone == NULL)
                sp = NULL;
        else
                while (sp != NULL) {
                        if (!strcmp(sp->name,zone))
                                break;
                        sp = sp->next;
                }

        if (sp == NULL) {
                ast_tzsetwall();
                sp = lclptr;
                /* Find the default zone record */
                while (sp != NULL) {
                        if (sp->name[0] == '\0')
                                break;
                        sp = sp->next;
                }
        }

        /* Last ditch effort, use GMT */
        if (sp == NULL) {
                gmtsub(timep, offset, tmp, zone);
                return;
        }
        if (sp->timecnt == 0 || t < sp->ats[0]) {
                i = 0;
                while (sp->ttis[i].tt_isdst)
                        if (++i >= sp->typecnt) {
                                i = 0;
                                break;
                        }
        } else {
                for (i = 1; i < sp->timecnt; ++i)
                        if (t < sp->ats[i])
                                break;
                i = sp->types[i - 1];
        }
        ttisp = &sp->ttis[i];
        /*
        ** To get (wrong) behavior that's compatible with System V Release 2.0
        ** you'd replace the statement below with
        **      t += ttisp->tt_gmtoff;
        **      timesub(&t, 0L, sp, tmp);
        */
        timesub(&t, ttisp->tt_gmtoff, sp, tmp);
        tmp->tm_isdst = ttisp->tt_isdst;
        tzname[tmp->tm_isdst] = &sp->chars[ttisp->tt_abbrind];
#ifdef TM_ZONE
        tmp->TM_ZONE = &sp->chars[ttisp->tt_abbrind];
#endif /* defined TM_ZONE */
}

struct tm *
ast_localtime(timep, p_tm, zone)
const time_t * const    timep;
struct tm *p_tm;
const char * const      zone;
{
#ifdef _THREAD_SAFE
        ast_mutex_lock(&lcl_mutex);
#endif
        ast_tzset(zone);
        localsub(timep, 0L, p_tm, zone);
#ifdef _THREAD_SAFE
        ast_mutex_unlock(&lcl_mutex);
#endif
        return(p_tm);
}

/*
** gmtsub is to gmtime as localsub is to localtime.
*/

static void
gmtsub(timep, offset, tmp, zone)
const time_t * const    timep;
const long              offset;
struct tm * const       tmp;
const char * const      zone;
{
#ifdef  _THREAD_SAFE
        ast_mutex_lock(&gmt_mutex);
#endif
        if (!gmt_is_set) {
                gmt_is_set = TRUE;
                gmtptr = (struct state *) malloc(sizeof *gmtptr);
                if (gmtptr != NULL)
                        gmtload(gmtptr);
        }
        ast_mutex_unlock(&gmt_mutex);
        timesub(timep, offset, gmtptr, tmp);
#ifdef TM_ZONE
        /*
        ** Could get fancy here and deliver something such as
        ** "GMT+xxxx" or "GMT-xxxx" if offset is non-zero,
        ** but this is no time for a treasure hunt.
        */
        if (offset != 0)
                tmp->TM_ZONE = wildabbr;
        else {
                if (gmtptr == NULL)
                        tmp->TM_ZONE = gmt;
                else    tmp->TM_ZONE = gmtptr->chars;
        }
#endif /* defined TM_ZONE */
}

static void
timesub(timep, offset, sp, tmp)
const time_t * const                    timep;
const long                              offset;
register const struct state * const     sp;
register struct tm * const              tmp;
{
        register const struct lsinfo *  lp;
        register long                   days;
        register long                   rem;
        register int                    y;
        register int                    yleap;
        register const int *            ip;
        register long                   corr;
        register int                    hit;
        register int                    i;

        corr = 0;
        hit = 0;
        i = (sp == NULL) ? 0 : sp->leapcnt;
        while (--i >= 0) {
                lp = &sp->lsis[i];
                if (*timep >= lp->ls_trans) {
                        if (*timep == lp->ls_trans) {
                                hit = ((i == 0 && lp->ls_corr > 0) ||
                                        lp->ls_corr > sp->lsis[i - 1].ls_corr);
                                if (hit)
                                        while (i > 0 &&
                                                sp->lsis[i].ls_trans ==
                                                sp->lsis[i - 1].ls_trans + 1 &&
                                                sp->lsis[i].ls_corr ==
                                                sp->lsis[i - 1].ls_corr + 1) {
                                                        ++hit;
                                                        --i;
                                        }
                        }
                        corr = lp->ls_corr;
                        break;
                }
        }
        days = *timep / SECSPERDAY;
        rem = *timep % SECSPERDAY;
#ifdef mc68k
        if (*timep == 0x80000000) {
                /*
                ** A 3B1 muffs the division on the most negative number.
                */
                days = -24855;
                rem = -11648;
        }
#endif /* defined mc68k */
        rem += (offset - corr);
        while (rem < 0) {
                rem += SECSPERDAY;
                --days;
        }
        while (rem >= SECSPERDAY) {
                rem -= SECSPERDAY;
                ++days;
        }
        tmp->tm_hour = (int) (rem / SECSPERHOUR);
        rem = rem % SECSPERHOUR;
        tmp->tm_min = (int) (rem / SECSPERMIN);
        /*
        ** A positive leap second requires a special
        ** representation.  This uses "... ??:59:60" et seq.
        */
        tmp->tm_sec = (int) (rem % SECSPERMIN) + hit;
        tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYSPERWEEK);
        if (tmp->tm_wday < 0)
                tmp->tm_wday += DAYSPERWEEK;
        y = EPOCH_YEAR;
#define LEAPS_THRU_END_OF(y)    ((y) / 4 - (y) / 100 + (y) / 400)
        while (days < 0 || days >= (long) year_lengths[yleap = isleap(y)]) {
                register int    newy;

                newy = y + days / DAYSPERNYEAR;
                if (days < 0)
                        --newy;
                days -= (newy - y) * DAYSPERNYEAR +
                        LEAPS_THRU_END_OF(newy - 1) -
                        LEAPS_THRU_END_OF(y - 1);
                y = newy;
        }
        tmp->tm_year = y - TM_YEAR_BASE;
        tmp->tm_yday = (int) days;
        ip = mon_lengths[yleap];
        for (tmp->tm_mon = 0; days >= (long) ip[tmp->tm_mon]; ++(tmp->tm_mon))
                days = days - (long) ip[tmp->tm_mon];
        tmp->tm_mday = (int) (days + 1);
        tmp->tm_isdst = 0;
#ifdef TM_GMTOFF
        tmp->TM_GMTOFF = offset;
#endif /* defined TM_GMTOFF */
}

char *
ast_ctime(timep)
const time_t * const    timep;
{
/*
** Section 4.12.3.2 of X3.159-1989 requires that
**      The ctime funciton converts the calendar time pointed to by timer
**      to local time in the form of a string.  It is equivalent to
**              asctime(localtime(timer))
*/
        return asctime(localtime(timep));
}

char *
ast_ctime_r(timep, buf)
const time_t * const    timep;
char *buf;
{
        struct tm tm;
#ifdef SOLARIS
        return asctime_r(localtime_r(timep, &tm), buf, 256);
#else
        return asctime_r(localtime_r(timep, &tm), buf);
#endif
}

/*
** Adapted from code provided by Robert Elz, who writes:
**      The "best" way to do mktime I think is based on an idea of Bob
**      Kridle's (so its said...) from a long time ago.
**      [kridle@xinet.com as of 1996-01-16.]
**      It does a binary search of the time_t space.  Since time_t's are
**      just 32 bits, its a max of 32 iterations (even at 64 bits it
**      would still be very reasonable).
*/

#ifndef WRONG
#define WRONG   (-1)
#endif /* !defined WRONG */

/*
** Simplified normalize logic courtesy Paul Eggert (eggert@twinsun.com).
*/

static int
increment_overflow(number, delta)
int *   number;
int     delta;
{
        int     number0;

        number0 = *number;
        *number += delta;
        return (*number < number0) != (delta < 0);
}

static int
normalize_overflow(tensptr, unitsptr, base)
int * const     tensptr;
int * const     unitsptr;
const int       base;
{
        register int    tensdelta;

        tensdelta = (*unitsptr >= 0) ?
                (*unitsptr / base) :
                (-1 - (-1 - *unitsptr) / base);
        *unitsptr -= tensdelta * base;
        return increment_overflow(tensptr, tensdelta);
}

static int
tmcomp(atmp, btmp)
register const struct tm * const atmp;
register const struct tm * const btmp;
{
        register int    result;

        if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
                (result = (atmp->tm_mon - btmp->tm_mon)) == 0 &&
                (result = (atmp->tm_mday - btmp->tm_mday)) == 0 &&
                (result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
                (result = (atmp->tm_min - btmp->tm_min)) == 0)
                        result = atmp->tm_sec - btmp->tm_sec;
        return result;
}

static time_t
time2(tmp, funcp, offset, okayp, zone)
struct tm * const       tmp;
void (* const           funcp) P((const time_t*, long, struct tm*, const char*));
const long              offset;
int * const             okayp;
const char * const      zone;
{
        register const struct state *   sp;
        register int                    dir;
        register int                    bits;
        register int                    i, j ;
        register int                    saved_seconds;
        time_t                          newt;
        time_t                          t;
        struct tm                       yourtm, mytm;

        *okayp = FALSE;
        yourtm = *tmp;
        if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR))
                return WRONG;
        if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY))
                return WRONG;
        if (normalize_overflow(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR))
                return WRONG;
        /*
        ** Turn yourtm.tm_year into an actual year number for now.
        ** It is converted back to an offset from TM_YEAR_BASE later.
        */
        if (increment_overflow(&yourtm.tm_year, TM_YEAR_BASE))
                return WRONG;
        while (yourtm.tm_mday <= 0) {
                if (increment_overflow(&yourtm.tm_year, -1))
                        return WRONG;
                i = yourtm.tm_year + (1 < yourtm.tm_mon);
                yourtm.tm_mday += year_lengths[isleap(i)];
        }
        while (yourtm.tm_mday > DAYSPERLYEAR) {
                i = yourtm.tm_year + (1 < yourtm.tm_mon);
                yourtm.tm_mday -= year_lengths[isleap(i)];
                if (increment_overflow(&yourtm.tm_year, 1))
                        return WRONG;
        }
        for ( ; ; ) {
                i = mon_lengths[isleap(yourtm.tm_year)][yourtm.tm_mon];
                if (yourtm.tm_mday <= i)
                        break;
                yourtm.tm_mday -= i;
                if (++yourtm.tm_mon >= MONSPERYEAR) {
                        yourtm.tm_mon = 0;
                        if (increment_overflow(&yourtm.tm_year, 1))
                                return WRONG;
                }
        }
        if (increment_overflow(&yourtm.tm_year, -TM_YEAR_BASE))
                return WRONG;
        if (yourtm.tm_year + TM_YEAR_BASE < EPOCH_YEAR) {
                /*
                ** We can't set tm_sec to 0, because that might push the
                ** time below the minimum representable time.
                ** Set tm_sec to 59 instead.
                ** This assumes that the minimum representable time is
                ** not in the same minute that a leap second was deleted from,
                ** which is a safer assumption than using 58 would be.
                */
                if (increment_overflow(&yourtm.tm_sec, 1 - SECSPERMIN))
                        return WRONG;
                saved_seconds = yourtm.tm_sec;
                yourtm.tm_sec = SECSPERMIN - 1;
        } else {
                saved_seconds = yourtm.tm_sec;
                yourtm.tm_sec = 0;
        }
        /*
        ** Divide the search space in half
        ** (this works whether time_t is signed or unsigned).
        */
        bits = TYPE_BIT(time_t) - 1;
        /*
        ** If time_t is signed, then 0 is just above the median,
        ** assuming two's complement arithmetic.
        ** If time_t is unsigned, then (1 << bits) is just above the median.
        */
        t = TYPE_SIGNED(time_t) ? 0 : (((time_t) 1) << bits);
        for ( ; ; ) {
                (*funcp)(&t, offset, &mytm, zone);
                dir = tmcomp(&mytm, &yourtm);
                if (dir != 0) {
                        if (bits-- < 0)
                                return WRONG;
                        if (bits < 0)
                                --t; /* may be needed if new t is minimal */
                        else if (dir > 0)
                                t -= ((time_t) 1) << bits;
                        else    t += ((time_t) 1) << bits;
                        continue;
                }
                if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
                        break;
                /*
                ** Right time, wrong type.
                ** Hunt for right time, right type.
                ** It's okay to guess wrong since the guess
                ** gets checked.
                */
                /*
                ** The (void *) casts are the benefit of SunOS 3.3 on Sun 2's.
                */
                sp = (const struct state *)
                        (((void *) funcp == (void *) localsub) ?
                        lclptr : gmtptr);
                if (sp == NULL)
                        return WRONG;
                for (i = sp->typecnt - 1; i >= 0; --i) {
                        if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
                                continue;
                        for (j = sp->typecnt - 1; j >= 0; --j) {
                                if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
                                        continue;
                                newt = t + sp->ttis[j].tt_gmtoff -
                                        sp->ttis[i].tt_gmtoff;
                                (*funcp)(&newt, offset, &mytm, zone);
                                if (tmcomp(&mytm, &yourtm) != 0)
                                        continue;
                                if (mytm.tm_isdst != yourtm.tm_isdst)
                                        continue;
                                /*
                                ** We have a match.
                                */
                                t = newt;
                                goto label;
                        }
                }
                return WRONG;
        }
label:
        newt = t + saved_seconds;
        if ((newt < t) != (saved_seconds < 0))
                return WRONG;
        t = newt;
        (*funcp)(&t, offset, tmp, zone);
        *okayp = TRUE;
        return t;
}

static time_t
time1(tmp, funcp, offset, zone)
struct tm * const       tmp;
void (* const           funcp) P((const time_t *, long, struct tm *, const char*));
const long              offset;
const char * const      zone;
{
        register time_t                 t;
        register const struct state *   sp;
        register int                    samei, otheri;
        int                             okay;

        if (tmp->tm_isdst > 1)
                tmp->tm_isdst = 1;
        t = time2(tmp, funcp, offset, &okay, zone);
#ifdef PCTS
        /*
        ** PCTS code courtesy Grant Sullivan (grant@osf.org).
        */
        if (okay)
                return t;
        if (tmp->tm_isdst < 0)
                tmp->tm_isdst = 0;      /* reset to std and try again */
#endif /* defined PCTS */
#ifndef PCTS
        if (okay || tmp->tm_isdst < 0)
                return t;
#endif /* !defined PCTS */
        /*
        ** We're supposed to assume that somebody took a time of one type
        ** and did some math on it that yielded a "struct tm" that's bad.
        ** We try to divine the type they started from and adjust to the
        ** type they need.
        */
        /*
        ** The (void *) casts are the benefit of SunOS 3.3 on Sun 2's.
        */
        sp = (const struct state *) (((void *) funcp == (void *) localsub) ?
                lclptr : gmtptr);
        if (sp == NULL)
                return WRONG;
        for (samei = sp->typecnt - 1; samei >= 0; --samei) {
                if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
                        continue;
                for (otheri = sp->typecnt - 1; otheri >= 0; --otheri) {
                        if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
                                continue;
                        tmp->tm_sec += sp->ttis[otheri].tt_gmtoff -
                                        sp->ttis[samei].tt_gmtoff;
                        tmp->tm_isdst = !tmp->tm_isdst;
                        t = time2(tmp, funcp, offset, &okay, zone);
                        if (okay)
                                return t;
                        tmp->tm_sec -= sp->ttis[otheri].tt_gmtoff -
                                        sp->ttis[samei].tt_gmtoff;
                        tmp->tm_isdst = !tmp->tm_isdst;
                }
        }
        return WRONG;
}

time_t
ast_mktime(tmp,zone)
struct tm * const       tmp;
const char * const      zone;
{
        time_t mktime_return_value;
#ifdef  _THREAD_SAFE
        ast_mutex_lock(&lcl_mutex);
#endif
        ast_tzset(zone);
        mktime_return_value = time1(tmp, localsub, 0L, zone);
#ifdef  _THREAD_SAFE
        ast_mutex_unlock(&lcl_mutex);
#endif
        return(mktime_return_value);
}