amiga-tz/localtime.c

#

/*LINTLIBRARY*/

#include "tzfile.h"
#include "time.h"

#ifdef OBJECTID
static char	sccsid[] = "%W%";
#endif

#ifndef TRUE
#define TRUE		1
#define FALSE		0
#endif

#ifndef MAXPATHLEN
#define MAXPATHLEN	1024
#endif

extern char *		getenv();
extern char *		strcpy();
extern char *		strcat();
extern char *		sprintf();

char *			asctime();
struct tm *		gmtime();

struct ttinfo {				/* time type information */
	long		tt_gmtoff;	/* GMT offset in seconds */
	int		tt_isdst;	/* used to set tm_isdst */
	int		tt_abbrind;	/* abbreviation list index */
};

struct state {
	int		timecnt;
	int		typecnt;
	int		charcnt;
	long		ats[TZ_MAX_TIMES];
	unsigned char	types[TZ_MAX_TIMES];
	struct ttinfo	ttis[TZ_MAX_TYPES];
	char		chars[TZ_MAX_CHARS + 1];
};

static struct state	s;

static char		isset;

char *			tzname[2] = { "GMT", "GMT" };

#ifdef TZ_ABBR
char *			tz_abbr;	/* compatibility w/older versions */
#endif

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

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

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

	if (name == 0 && (name = TZDEFAULT) == 0)
		return -1;
	{
		register char *	p;
		register int	doaccess;
		char		fullname[MAXPATHLEN];

		doaccess = name[0] == '/';
		if (!doaccess) {
			if ((p = TZDIR) == 0)
				return -1;
			if ((strlen(p) + strlen(name) + 1) >= sizeof fullname)
				return -1;
			(void) strcpy(fullname, p);
			(void) strcat(fullname, "/");
			(void) strcat(fullname, name);
			/*
			** Set doaccess if '.' (as in "../") shows up in name.
			*/
			while (*name != '\0')
				if (*name++ == '.')
					doaccess = TRUE;
			name = fullname;
		}
		if (doaccess && access(name, 4) != 0)
			return -1;
		if ((fid = open(name, 0)) == -1)
			return -1;
	}
	{
		register char *			p;
		register struct tzhead *	tzhp;
		char				buf[sizeof s];

		i = read(fid, buf, sizeof buf);
		if (close(fid) != 0 || i < sizeof *tzhp)
			return -1;
		tzhp = (struct tzhead *) buf;
		sp->timecnt = detzcode(tzhp->tzh_timecnt);
		sp->typecnt = detzcode(tzhp->tzh_typecnt);
		sp->charcnt = detzcode(tzhp->tzh_charcnt);
		if (sp->timecnt > TZ_MAX_TIMES ||
			sp->typecnt == 0 ||
			sp->typecnt > TZ_MAX_TYPES ||
			sp->charcnt > TZ_MAX_CHARS)
				return -1;
		if (i < sizeof *tzhp +
			sp->timecnt * (4 + sizeof (char)) +
			sp->typecnt * (4 + 2 * sizeof (char)) +
			sp->charcnt * sizeof (char))
				return -1;
		p = buf + sizeof *tzhp;
		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++;
		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++;
			ttisp->tt_abbrind = (unsigned char) *p++;
		}
		for (i = 0; i < sp->charcnt; ++i)
			sp->chars[i] = *p++;
		sp->chars[i] = '\0';	/* ensure '\0' at end */
	}
	/*
	** Check that all the local time type indices are valid.
	*/
	for (i = 0; i < sp->timecnt; ++i)
		if (sp->types[i] >= sp->typecnt)
			return -1;
	/*
	** Check that all abbreviation indices are valid.
	*/
	for (i = 0; i < sp->typecnt; ++i)
		if (sp->ttis[i].tt_abbrind >= sp->charcnt)
			return -1;
	/*
	** Set tzname elements to initial values.
	*/
	tzname[0] = tzname[1] = &sp->chars[0];
	for (i = 1; i < sp->typecnt; ++i) {
		register struct ttinfo *	ttisp;

		ttisp = &sp->ttis[i];
		tzname[ttisp->tt_isdst != 0] = &sp->chars[ttisp->tt_abbrind];
	}
	return 0;
}

/*
** settz("")		Use built-in GMT.
** settz((char *) 0)	Use TZDEFAULT.
** settz(otherwise)	Use otherwise.
*/

settz(name)
char *	name;
{
	register int	result;

	isset = TRUE;
	if (name != 0 && *name == '\0')
		result = 0;			/* Use built-in GMT */
	else {
		if (tzload(name, &s) == 0)
			return 0;
		/*
		** If we want to try for local time on errors. . .
		if (tzload((char *) 0, &s) == 0)
			return -1;
		*/
		result = -1;
	}
	s.timecnt = 0;
	s.ttis[0].tt_gmtoff = 0;
	s.ttis[0].tt_abbrind = 0;
	(void) strcpy(s.chars, "GMT");
	tzname[0] = tzname[1] = s.chars;
	return result;
}

static struct tm *
timesub(timep, sp)
register long *		timep;
register struct state *	sp;
{
	register struct ttinfo *	ttisp;
	register struct tm *		tmp;
	register int			i;
	long				t;

	t = *timep;
	if (sp->timecnt == 0 || t < sp->ats[0]) {
		i = 0;
		while (sp->ttis[i].tt_isdst)
			if (++i >= sp->timecnt) {
				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];
	t += ttisp->tt_gmtoff;
	tmp = gmtime(&t);
	tmp->tm_isdst = ttisp->tt_isdst;
#ifdef TZ_ABBR
	tz_abbr =
#endif
	tzname[tmp->tm_isdst] = &sp->chars[ttisp->tt_abbrind];
	return tmp;
}

struct tm *
localtime(timep)
long *	timep;
{
	if (!isset)
		(void) settz(getenv("TZ"));
	return timesub(timep, &s);
}

struct tm *
zonetime(timep, zone)
long *	timep;
char *	zone;
{
	/*
	** This struct needs to be static since tzname[i] may end up pointing
	** to it.  Alternately, localtime might copy time zone abbreviations
	** into small buffers.  We'll take the easy way out for now.
	*/
	static struct state	st;

	return (tzload(zone, &st) == 0) ? timesub(timep, &st) : 0;
}

char *
ctime(timep)
long *	timep;
{
	return asctime(localtime(timep));
}

/*
********************************************************************************
*/

#define SECS_PER_MIN	60
#define MINS_PER_HOUR	60
#define HOURS_PER_DAY	24
#define DAYS_PER_WEEK	7
#define SECS_PER_HOUR	(SECS_PER_MIN * MINS_PER_HOUR)
#define SECS_PER_DAY	((long) SECS_PER_HOUR * HOURS_PER_DAY)

#define TM_SUNDAY	0
#define TM_MONDAY	1
#define TM_TUESDAY	2
#define TM_WEDNESDAY	3
#define TM_THURSDAY	4
#define TM_FRIDAY	5
#define TM_SATURDAY	6

#define TM_YEAR_BASE	1900

#define EPOCH_YEAR	1970
#define EPOCH_WDAY	TM_THURSDAY

static int	mon_lengths[2][12] = {	/* ". . .knuckles are 31. . ." */
	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 int	year_lengths[2] = {
	365, 366
};

/*
** Since the times representable in a 32-bit signed integer
** run from 1901 to 2037, the define below works--2000 IS a leap year.
*/

#define isleap(y) (((y) % 4) == 0)

struct tm *
gmtime(clock)
long *	clock;
{
	register struct tm *	tmp;
	register long		days;
	register long		rem;
	register int		y;
	register int		yleap;
	register int *		ip;
	static struct tm	tm;

	tmp = &tm;
	y = EPOCH_YEAR;
	days = *clock / SECS_PER_DAY;
	rem = *clock % SECS_PER_DAY;
	if (rem < 0) {
		rem = rem + SECS_PER_DAY;
		--days;
	}
	tmp->tm_hour = (int) (rem / SECS_PER_HOUR);
	rem = rem % SECS_PER_HOUR;
	tmp->tm_min = (int) (rem / SECS_PER_MIN);
	tmp->tm_sec = (int) (rem % SECS_PER_MIN);
	tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYS_PER_WEEK);
	if (tmp->tm_wday < 0)
		tmp->tm_wday += DAYS_PER_WEEK;
	y = EPOCH_YEAR;
	if (days >= 0)
		for ( ; ; ) {
			yleap = isleap(y);
			if (days < (long) year_lengths[yleap])
				break;
			++y;
			days = days - (long) year_lengths[yleap];
		}
	else do {
		--y;
		yleap = isleap(y);
		days = days + (long) year_lengths[yleap];
	} while (days < 0);
	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;
	return tmp;
}

/*
** A la X3J11
*/

char *
asctime(timeptr)
register struct tm *	timeptr;
{
	static char	wday_name[7][3] = {
		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
	};
	static char	mon_name[12][3] = {
		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
	};
	static char	result[26];

	(void) sprintf(result, "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n",
		wday_name[timeptr->tm_wday],
		mon_name[timeptr->tm_mon],
		timeptr->tm_mday, timeptr->tm_hour,
		timeptr->tm_min, timeptr->tm_sec,
		TM_YEAR_BASE + timeptr->tm_year);
	return result;
}

/*
** System V compatability.
*/

void
tzset()
{
	(void) settz((char *) 0);
}