/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ /* * This routine converts time as follows. * The epoch is 0000 Jan 1 1970 GMT. * The argument time is in seconds since then. * The localtime(t) entry returns a pointer to an array * containing * *	seconds (0-59) *	minutes (0-59) *	hours (0-23) *	day of month (1-31) *	month (0-11) *	year-1970 *	weekday (0-6, Sun is 0) *	day of the year *	daylight savings flag * * The routine gets the daylight savings time from the environment. * * asctime(tvec)) * where tvec is produced by localtime * returns a ptr to a character string * that has the ascii time in the form * *	                            \\ *	Thu Jan 01 00:00:00 GMT 1970n0 *	012345678901234567890123456789 *	0	  1	    2 * * ctime(t) just calls localtime, then asctime. */ #include <u.h>#include <libc.h> static	char	dmsize[12] ={	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; /* * The following table is used for 1974 and 1975 and * gives the day number of the first day after the Sunday of the * change. */ static	int	dysize(int);static	void	ct_numb(char*, int); #define	TZSIZE	150static	void	readtimezone(void);static	int	rd_name(char**, char*);static	int	rd_long(char**, long*);staticstruct{	char	stname[4];	char	dlname[4];	long	stdiff;	long	dldiff;	long	dlpairs[TZSIZE];} timezone; char*ctime(long t){	return asctime(localtime(t));} Tm*localtime(long tim){	Tm *ct;	long t, *p;	int dlflag; 	if(timezone.stname[0] == 0)		readtimezone();	t = tim + timezone.stdiff;	dlflag = 0;	for(p = timezone.dlpairs; *p; p += 2)		if(t >= p[0])		if(t < p[1]) {			t = tim + timezone.dldiff;			dlflag++;			break;		}	ct = gmtime(t);	if(dlflag){		strcpy(ct->zone, timezone.dlname);		ct->tzoff = timezone.dldiff;	} else {		strcpy(ct->zone, timezone.stname);		ct->tzoff = timezone.stdiff;	}	return ct;} Tm*gmtime(long tim){	int d0, d1;	long hms, day;	static Tm xtime; 	/*	 * break initial number into days	 */	hms = (ulong)tim % 86400L;	day = (ulong)tim / 86400L;	if(hms < 0) {		hms += 86400L;		day -= 1;	} 	/*	 * generate hours:minutes:seconds	 */	xtime.sec = hms % 60;	d1 = hms / 60;	xtime.min = d1 % 60;	d1 /= 60;	xtime.hour = d1; 	/*	 * day is the day number.	 * generate day of the week.	 * The addend is 4 mod 7 (1/1/1970 was Thursday)	 */ 	xtime.wday = (day + 7340036L) % 7; 	/*	 * year number	 */	if(day >= 0)		for(d1 = 1970; day >= dysize(d1); d1++)			day -= dysize(d1);	else		for (d1 = 1970; day < 0; d1--)			day += dysize(d1-1);	xtime.year = d1-1900;	xtime.yday = d0 = day; 	/*	 * generate month	 */ 	if(dysize(d1) == 366)		dmsize[1] = 29;	for(d1 = 0; d0 >= dmsize[d1]; d1++)		d0 -= dmsize[d1];	dmsize[1] = 28;	xtime.mday = d0 + 1;	xtime.mon = d1;	strcpy(xtime.zone, "GMT");	return &xtime;} char*asctime(Tm *t){	char *ncp;	static char cbuf[30]; 	strcpy(cbuf, "Thu Jan 01 00:00:00 GMT 1970\n");	ncp = &"SunMonTueWedThuFriSat"[t->wday*3];	cbuf[0] = *ncp++;	cbuf[1] = *ncp++;	cbuf[2] = *ncp;	ncp = &"JanFebMarAprMayJunJulAugSepOctNovDec"[t->mon*3];	cbuf[4] = *ncp++;	cbuf[5] = *ncp++;	cbuf[6] = *ncp;	ct_numb(cbuf+8, t->mday);	ct_numb(cbuf+11, t->hour+100);	ct_numb(cbuf+14, t->min+100);	ct_numb(cbuf+17, t->sec+100);	ncp = t->zone;	cbuf[20] = *ncp++;	cbuf[21] = *ncp++;	cbuf[22] = *ncp;	if(t->year >= 100) {		cbuf[24] = '2';		cbuf[25] = '0';	}	ct_numb(cbuf+26, t->year+100);	return cbuf;} staticdysize(int y){ 	if(y%4 == 0 && (y%100 != 0 || y%400 == 0))		return 366;	return 365;} staticvoidct_numb(char *cp, int n){ 	cp[0] = ' ';	if(n >= 10)		cp[0] = (n/10)%10 + '0';	cp[1] = n%10 + '0';} staticvoidreadtimezone(void){	char buf[TZSIZE*11+30], *p;	int i; 	memset(buf, 0, sizeof(buf));	i = open("/env/timezone", 0);	if(i < 0)		goto error;	if(read(i, buf, sizeof(buf)) >= sizeof(buf)){		close(i);		goto error;	}	close(i);	p = buf;	if(rd_name(&p, timezone.stname))		goto error;	if(rd_long(&p, &timezone.stdiff))		goto error;	if(rd_name(&p, timezone.dlname))		goto error;	if(rd_long(&p, &timezone.dldiff))		goto error;	for(i=0; i<TZSIZE; i++) {		if(rd_long(&p, &timezone.dlpairs[i]))			goto error;		if(timezone.dlpairs[i] == 0)			return;	} error:	timezone.stdiff = 0;	strcpy(timezone.stname, "GMT");	timezone.dlpairs[0] = 0;} staticrd_name(char **f, char *p){	int c, i; 	for(;;) {		c = *(*f)++;		if(c != ' ' && c != '\n')			break;	}	for(i=0; i<3; i++) {		if(c == ' ' || c == '\n')			return 1;		*p++ = c;		c = *(*f)++;	}	if(c != ' ' && c != '\n')		return 1;	*p = 0;	return 0;} staticrd_long(char **f, long *p){	int c, s;	long l; 	s = 0;	for(;;) {		c = *(*f)++;		if(c == '-') {			s++;			continue;		}		if(c != ' ' && c != '\n')			break;	}	if(c == 0) {		*p = 0;		return 0;	}	l = 0;	for(;;) {		if(c == ' ' || c == '\n')			break;		if(c < '0' || c > '9')			return 1;		l = l*10 + c-'0';		c = *(*f)++;	}	if(s)		l = -l;	*p = l;	return 0;}