/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License, Version 1.0 only

 * (the "License").  You may not use this file except in compliance

 * with the License.

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

/*	Copyright (c) 1988 AT&T	*/

/*	  All Rights Reserved  	*/

/*

 * 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 corrects for daylight saving

 * time and will work in any time zone provided

 * "timezone" is adjusted to the difference between

 * Greenwich and local standard time (measured in seconds).

 * In places like Michigan "daylight" must

 * be initialized to 0 to prevent the conversion

 * to daylight time.

 * There is a table which accounts for the peculiarities

 * undergone by daylight time in 1974-1975.

 *

 * The routine does not work

 * in Saudi Arabia which runs on Solar time.

 *

 * 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 1970\n\0

 *	01234567890123456789012345

 *	0	  1	    2

 *

 * ctime(t) just calls localtime, then asctime.

 *

 * tzset() looks for an environment variable named

 * TZ.

 * If the variable is present, it will set the external

 * variables "timezone", "altzone", "daylight", and "tzname"

 * appropriately. It is called by localtime, and

 * may also be called explicitly by the user.

 */

#pragma weak asctime_r = _asctime_r

#include "synonyms.h"

#include <mtlib.h>

#include <sys/types.h>

#include <time.h>

#include <errno.h>

#include <thread.h>

#include <synch.h>

#include "libc.h"

#include "tsd.h"

#define	dysize(A) (((A)%4)? 365: 366)

#define	CBUFSIZ 26

static char *

ct_numb(char *cp, int n)

{

	cp++;

	if (n >= 10)

		*cp++ = (n / 10) % 10 + '0';

	else

		*cp++ = ' ';		/* Pad with blanks */

	*cp++ = n % 10 + '0';

	return (cp);

}

/*

 * POSIX.1c standard version of the function asctime_r.

 * User gets it via static asctime_r from the header file.

 */

char *

__posix_asctime_r(const struct tm *t, char *cbuf)

{

	char *cp;

	const char *ncp;

	const int *tp;

	const char *Date = "Day Mon 00 00:00:00 1900\n";

	const char *Day  = "SunMonTueWedThuFriSat";

	const char *Month = "JanFebMarAprMayJunJulAugSepOctNovDec";

	cp = cbuf;

	for (ncp = Date; *cp++ = *ncp++; /* */);

	ncp = Day + (3 * t->tm_wday);

	cp = cbuf;

	*cp++ = *ncp++;

	*cp++ = *ncp++;

	*cp++ = *ncp++;

	cp++;

	tp = &t->tm_mon;

	ncp = Month + ((*tp) * 3);

	*cp++ = *ncp++;

	*cp++ = *ncp++;

	*cp++ = *ncp++;

	cp = ct_numb(cp, *--tp);

	cp = ct_numb(cp, *--tp + 100);

	cp = ct_numb(cp, *--tp + 100);

	--tp;

	cp = ct_numb(cp, *tp + 100);

	if (t->tm_year < 100) {

		/* Common case: "19" already in buffer */

		cp += 2;

	} else if (t->tm_year < 8100) {

		cp = ct_numb(cp, (1900 + t->tm_year) / 100);

		cp--;

	} else {

		/* Only 4-digit years are supported */

		errno = EOVERFLOW;

		return (NULL);

	}

	(void) ct_numb(cp, t->tm_year + 100);

	return (cbuf);

}

/*

 * POSIX.1c Draft-6 version of the function asctime_r.

 * It was implemented by Solaris 2.3.

 */

char *

asctime_r(const struct tm *t, char *cbuf, int buflen)

{

	if (buflen < CBUFSIZ) {

		errno = ERANGE;

		return (NULL);

	}

	return (__posix_asctime_r(t, cbuf));

}

char *

ctime(const time_t *t)

{

	char *cbuf = tsdalloc(_T_CTIME, CBUFSIZ, NULL);

	struct tm *p;

	if (cbuf == NULL)

		return (NULL);

	p = localtime(t);

	if (p == NULL)

		return (NULL);

	return (__posix_asctime_r(p, cbuf));

}

char *

asctime(const struct tm *t)

{

	char *cbuf = tsdalloc(_T_CTIME, CBUFSIZ, NULL);

	if (cbuf == NULL)

		return (NULL);

	return (__posix_asctime_r(t, cbuf));

}