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cosmopolitan/third_party/unzip/timezone.c
Justine Tunney b0df6c1fce
Implement proper time zone support 
Cosmopolitan now supports 104 time zones. They're embedded inside any
binary that links the localtime() function. Doing so adds about 100kb
to the binary size. This change also gets time zones working properly
on Windows for the first time. It's not needed to have /etc/localtime
exist on Windows, since we can get this information from WIN32. We're
also now updated to the latest version of Paul Eggert's TZ library.
2024-05-04 23:06:37 -07:00

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/*
Copyright (c) 1990-2001 Info-ZIP. All rights reserved.
See the accompanying file LICENSE, version 2000-Apr-09 or later
(the contents of which are also included in zip.h) for terms of use.
If, for some reason, all these files are missing, the Info-ZIP license
also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html
*/
/* Replacement time library functions, based on platform independent public
* domain timezone code from ftp://elsie.nci.nih.gov/pub, with mktime and
* mkgmtime from our own mktime.c in Zip.
*
* Contains: tzset()
* __tzset()
* gmtime()
* localtime()
* mktime()
* mkgmtime()
* GetPlatformLocalTimezone() [different versions]
*/
/* HISTORY/CHANGES
* 17 Jun 00, Paul Kienitz, added the PD-based tzset(), localtime(), and so on
* to amiga/filedate.c, replacing GNU-based functions which had
* replaced time_lib.c, both having been rejected for licensing
* reasons. Support for timezone files and leap seconds was removed.
*
* 23 Aug 00, Paul Kienitz, split into separate timezone.c file, made platform
* independent, copied in mktime() and mkgmtime() from Zip, renamed
* locale_TZ as GetPlatformLocalTimezone(), for use as a generic
* hook by other platforms.
*/
#ifndef __timezone_c
#define __timezone_c
#include "third_party/unzip/zip.h"
#include "libc/time.h"
#include "third_party/unzip/timezone.h"
#ifdef IZTZ_DEFINESTDGLOBALS
long timezone = 0;
int daylight = 0;
char *tzname[2];
#endif
#ifndef IZTZ_GETLOCALETZINFO
# define IZTZ_GETLOCALETZINFO(ptzstruct, pgenrulefunct) (FALSE)
#endif
int real_timezone_is_set = FALSE; /* set by tzset() */
#define TZDEFRULESTRING ",M4.1.0,M10.5.0"
#define TZDEFAULT "EST5EDT"
#define SECSPERMIN 60
#define MINSPERHOUR 60
#define HOURSPERDAY 24
#define DAYSPERWEEK 7
#define DAYSPERNYEAR 365
#define DAYSPERLYEAR 366
#define SECSPERHOUR (SECSPERMIN * MINSPERHOUR)
#define SECSPERDAY ((long) SECSPERHOUR * HOURSPERDAY)
#define MONSPERYEAR 12
#define EPOCH_WDAY 4 /* Jan 1, 1970 was thursday */
#define EPOCH_YEAR 1970
#define TM_YEAR_BASE 1900
#define FIRST_GOOD_YEAR ((time_t) -1 < (time_t) 1 ? EPOCH_YEAR-68 : EPOCH_YEAR)
#define LAST_GOOD_YEAR (EPOCH_YEAR + ((time_t) -1 < (time_t) 1 ? 67 : 135))
#define YDAYS(month, year) yr_days[leap(year)][month]
/* Nonzero if `y' is a leap year, else zero. */
#define leap(y) (((y) % 4 == 0 && (y) % 100 != 0) || (y) % 400 == 0)
/* Number of leap years from EPOCH_YEAR to `y' (not including `y' itself). */
#define _P4 ((EPOCH_YEAR / 4) * 4 + 1)
#define _P100 ((EPOCH_YEAR / 100) * 100 + 1)
#define _P400 ((EPOCH_YEAR / 400) * 400 + 1)
#define nleap(y) (((y) - _P4) / 4 - ((y) - _P100) / 100 + ((y) - _P400) / 400)
/* Length of month `m' (0 .. 11) */
#define monthlen(m, y) (yr_days[0][(m)+1] - yr_days[0][m] + \
((m) == 1 && leap(y)))
/* internal module-level constants */
#ifndef IZ_MKTIME_ONLY
static ZCONST char gmt[] = "GMT";
static ZCONST 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 }
};
#endif /* !IZ_MKTIME_ONLY */
static ZCONST int yr_days[2][MONSPERYEAR+1] = {
{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
};
#ifndef IZ_MKTIME_ONLY
static ZCONST int year_lengths[2] = {
DAYSPERNYEAR, DAYSPERLYEAR
};
/* internal variables */
static struct state statism;
/* prototypes of static functions */
static time_t transtime OF((ZCONST time_t janfirst, ZCONST int year,
ZCONST struct rule * ZCONST rulep,
ZCONST long offset));
static void generate_transitions OF((register struct state * ZCONST sp,
ZCONST struct rule * ZCONST start,
ZCONST struct rule * ZCONST end));
static ZCONST char *getzname OF((ZCONST char *strp));
static ZCONST char *getnum OF((ZCONST char *strp, int * ZCONST nump,
ZCONST int min, ZCONST int max));
static ZCONST char *getsecs OF((ZCONST char *strp, long * ZCONST secsp));
static ZCONST char *getoffset OF((ZCONST char *strp, long * ZCONST offsetp));
static ZCONST char *getrule OF((ZCONST char *strp, struct rule * ZCONST rulep));
static int Parse_TZ OF((ZCONST char *name, register struct state * ZCONST sp));
static time_t transtime(janfirst, year, rulep, offset)
ZCONST time_t janfirst;
ZCONST int year;
ZCONST struct rule * ZCONST rulep;
ZCONST long offset;
{
register int leapyear;
register time_t value;
register int i;
int d, m1, yy0, yy1, yy2, dow;
value = 0;
leapyear = leap(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;
*/
value += yr_days[leapyear][rulep->r_mon - 1] * 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 UTC 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 UTC.
*/
return value + rulep->r_time + offset;
}
static void generate_transitions(sp, start, end)
register struct state * ZCONST sp;
ZCONST struct rule * ZCONST start;
ZCONST struct rule * ZCONST end;
{
register int year;
register time_t janfirst;
time_t starttime;
time_t endtime;
long stdoffset = -sp->ttis[0].tt_gmtoff;
long dstoffset = -sp->ttis[1].tt_gmtoff;
register time_t * atp;
register unsigned char * typep;
/*
** Two transitions per year, from EPOCH_YEAR to LAST_GOOD_YEAR.
*/
sp->timecnt = 2 * (LAST_GOOD_YEAR - EPOCH_YEAR + 1);
atp = sp->ats;
typep = sp->types;
janfirst = 0;
for (year = EPOCH_YEAR; year <= LAST_GOOD_YEAR; ++year) {
starttime = transtime(janfirst, year, start, stdoffset);
endtime = transtime(janfirst, year, end, dstoffset);
if (starttime > endtime) {
*atp++ = endtime;
*typep++ = 0; /* DST ends */
*atp++ = starttime;
*typep++ = 1; /* DST begins */
} else {
*atp++ = starttime;
*typep++ = 1; /* DST begins */
*atp++ = endtime;
*typep++ = 0; /* DST ends */
}
janfirst += year_lengths[leap(year)] * SECSPERDAY;
}
}
static ZCONST char *getzname(strp)
ZCONST char *strp;
{
register char c;
while ((c = *strp) != '\0' && !isdigit(c) && c != ',' && c != '-' &&
c != '+')
++strp;
return strp;
}
static ZCONST char *getnum(strp, nump, min, max)
ZCONST char *strp;
int * ZCONST nump;
ZCONST int min;
ZCONST int max;
{
register char c;
register int num;
if (strp == NULL || !isdigit(c = *strp))
return NULL;
num = 0;
do {
num = num * 10 + (c - '0');
if (num > max)
return NULL; /* illegal value */
c = *++strp;
} while (isdigit(c));
if (num < min)
return NULL; /* illegal value */
*nump = num;
return strp;
}
static ZCONST char *getsecs(strp, secsp)
ZCONST char *strp;
long * ZCONST 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;
}
static ZCONST char *getoffset(strp, offsetp)
ZCONST char *strp;
long * ZCONST 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;
}
static ZCONST char *getrule(strp, rulep)
ZCONST char *strp;
struct rule * ZCONST 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 (isdigit(*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;
}
static int Parse_TZ(name, sp)
ZCONST char *name;
register struct state * ZCONST sp;
{
ZCONST char * stdname;
ZCONST char * dstname;
size_t stdlen;
size_t dstlen;
long stdoffset;
long dstoffset;
register char * cp;
dstname = NULL;
stdname = name;
name = getzname(name);
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 = 0; /* 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 */
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