/*

 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/.

 *

 * See the COPYRIGHT file distributed with this work for additional

 * information regarding copyright ownership.

 */

/*-

 * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.

 * All rights reserved.

 *

 * This code was contributed to The NetBSD Foundation by Klaus Klein.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS

 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED

 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS

 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGE.

 */

#include <config.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <time.h>

#include <ctype.h>

#include <isc/tm.h>

#include <isc/util.h>

/*

 * Portable conversion routines for struct tm, replacing

 * timegm() and strptime(), which are not available on all

 * platforms and don't always behave the same way when they

 * are.

 */

/*

 * We do not implement alternate representations. However, we always

 * check whether a given modifier is allowed for a certain conversion.

 */

#define ALT_E			0x01

#define ALT_O			0x02

#define	LEGAL_ALT(x)		{ if ((alt_format & ~(x)) != 0) return (0); }

#ifndef TM_YEAR_BASE

#define TM_YEAR_BASE 1900

#endif

static const char *day[7] = {

	"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",

	"Friday", "Saturday"

};

static const char *abday[7] = {

	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"

};

static const char *mon[12] = {

	"January", "February", "March", "April", "May", "June", "July",

	"August", "September", "October", "November", "December"

};

static const char *abmon[12] = {

	"Jan", "Feb", "Mar", "Apr", "May", "Jun",

	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"

};

static const char *am_pm[2] = {

	"AM", "PM"

};

static int

conv_num(const char **buf, int *dest, int llim, int ulim) {

	int result = 0;

	/* The limit also determines the number of valid digits. */

	int rulim = ulim;

	if (**buf < '0' || **buf > '9')

		return (0);

	do {

		result *= 10;

		result += *(*buf)++ - '0';

		rulim /= 10;

	} while ((result * 10 <= ulim) &&

		 rulim && **buf >= '0' && **buf <= '9');

	if (result < llim || result > ulim)

		return (0);

	*dest = result;

	return (1);

}

time_t

isc_tm_timegm(struct tm *tm) {

	time_t ret;

	int i, yday = 0, leapday;

	int mdays[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30 };

	leapday = ((((tm->tm_year + 1900 ) % 4) == 0 &&

		    ((tm->tm_year + 1900 ) % 100) != 0) ||

		   ((tm->tm_year + 1900 ) % 400) == 0) ? 1 : 0;

	mdays[1] += leapday;

	yday = tm->tm_mday - 1;

	for (i = 1; i <= tm->tm_mon; i++)

		yday += mdays[i - 1];

	ret = tm->tm_sec +

	      (60 * tm->tm_min) +

	      (3600 * tm->tm_hour) +

	      (86400 * (yday +

		       ((tm->tm_year - 70) * 365) +

		       ((tm->tm_year - 69) / 4) -

		       ((tm->tm_year - 1) / 100) +

		       ((tm->tm_year + 299) / 400)));

	return (ret);

}

char *

isc_tm_strptime(const char *buf, const char *fmt, struct tm *tm) {

	char c, *ret;

	const char *bp;

	size_t len = 0;

	int alt_format, i, split_year = 0;

	REQUIRE(buf != NULL);

	REQUIRE(fmt != NULL);

	REQUIRE(tm != NULL);

	memset(tm, 0, sizeof(struct tm));

	bp = buf;

	while ((c = *fmt) != '\0') {

		/* Clear `alternate' modifier prior to new conversion. */

		alt_format = 0;

		/* Eat up white-space. */

		if (isspace((unsigned char) c)) {

			while (isspace((unsigned char) *bp))

				bp++;

			fmt++;

			continue;

		}

		if ((c = *fmt++) != '%')

			goto literal;

again:		switch (c = *fmt++) {

		case '%':	/* "%%" is converted to "%". */

literal:

			if (c != *bp++)

				return (0);

			break;

		/*

		 * "Alternative" modifiers. Just set the appropriate flag

		 * and start over again.

		 */

		case 'E':	/* "%E?" alternative conversion modifier. */

			LEGAL_ALT(0);

			alt_format |= ALT_E;

			goto again;

		case 'O':	/* "%O?" alternative conversion modifier. */

			LEGAL_ALT(0);

			alt_format |= ALT_O;

			goto again;

		/*

		 * "Complex" conversion rules, implemented through recursion.

		 */

		case 'c':	/* Date and time, using the locale's format. */

			LEGAL_ALT(ALT_E);

			if (!(bp = isc_tm_strptime(bp, "%x %X", tm)))

				return (0);

			break;

		case 'D':	/* The date as "%m/%d/%y". */

			LEGAL_ALT(0);

			if (!(bp = isc_tm_strptime(bp, "%m/%d/%y", tm)))

				return (0);

			break;

		case 'R':	/* The time as "%H:%M". */

			LEGAL_ALT(0);

			if (!(bp = isc_tm_strptime(bp, "%H:%M", tm)))

				return (0);

			break;

		case 'r':	/* The time in 12-hour clock representation. */

			LEGAL_ALT(0);

			if (!(bp = isc_tm_strptime(bp, "%I:%M:%S %p", tm)))

				return (0);

			break;

		case 'T':	/* The time as "%H:%M:%S". */

			LEGAL_ALT(0);

			if (!(bp = isc_tm_strptime(bp, "%H:%M:%S", tm)))

				return (0);

			break;

		case 'X':	/* The time, using the locale's format. */

			LEGAL_ALT(ALT_E);

			if (!(bp = isc_tm_strptime(bp, "%H:%M:%S", tm)))

				return (0);

			break;

		case 'x':	/* The date, using the locale's format. */

			LEGAL_ALT(ALT_E);

			if (!(bp = isc_tm_strptime(bp, "%m/%d/%y", tm)))

				return (0);

			break;

		/*

		 * "Elementary" conversion rules.

		 */

		case 'A':	/* The day of week, using the locale's form. */

		case 'a':

			LEGAL_ALT(0);

			for (i = 0; i < 7; i++) {

				/* Full name. */

				len = strlen(day[i]);

				if (strncasecmp(day[i], bp, len) == 0)

					break;

				/* Abbreviated name. */

				len = strlen(abday[i]);

				if (strncasecmp(abday[i], bp, len) == 0)

					break;

			}

			/* Nothing matched. */

			if (i == 7)

				return (0);

			tm->tm_wday = i;

			bp += len;

			break;

		case 'B':	/* The month, using the locale's form. */

		case 'b':

		case 'h':

			LEGAL_ALT(0);

			for (i = 0; i < 12; i++) {

				/* Full name. */

				len = strlen(mon[i]);

				if (strncasecmp(mon[i], bp, len) == 0)

					break;

				/* Abbreviated name. */

				len = strlen(abmon[i]);

				if (strncasecmp(abmon[i], bp, len) == 0)

					break;

			}

			/* Nothing matched. */

			if (i == 12)

				return (0);

			tm->tm_mon = i;

			bp += len;

			break;

		case 'C':	/* The century number. */

			LEGAL_ALT(ALT_E);

			if (!(conv_num(&bp, &i, 0, 99)))

				return (0);

			if (split_year) {

				tm->tm_year = (tm->tm_year % 100) + (i * 100);

			} else {

				tm->tm_year = i * 100;

				split_year = 1;

			}

			break;

		case 'd':	/* The day of month. */

		case 'e':

			LEGAL_ALT(ALT_O);

			if (!(conv_num(&bp, &tm->tm_mday, 1, 31)))

				return (0);

			break;

		case 'k':	/* The hour (24-hour clock representation). */

			LEGAL_ALT(0);

			/* FALLTHROUGH */

		case 'H':

			LEGAL_ALT(ALT_O);

			if (!(conv_num(&bp, &tm->tm_hour, 0, 23)))

				return (0);

			break;

		case 'l':	/* The hour (12-hour clock representation). */

			LEGAL_ALT(0);

			/* FALLTHROUGH */

		case 'I':

			LEGAL_ALT(ALT_O);

			if (!(conv_num(&bp, &tm->tm_hour, 1, 12)))

				return (0);

			if (tm->tm_hour == 12)

				tm->tm_hour = 0;

			break;

		case 'j':	/* The day of year. */

			LEGAL_ALT(0);

			if (!(conv_num(&bp, &i, 1, 366)))

				return (0);

			tm->tm_yday = i - 1;

			break;

		case 'M':	/* The minute. */

			LEGAL_ALT(ALT_O);

			if (!(conv_num(&bp, &tm->tm_min, 0, 59)))

				return (0);

			break;

		case 'm':	/* The month. */

			LEGAL_ALT(ALT_O);

			if (!(conv_num(&bp, &i, 1, 12)))

				return (0);

			tm->tm_mon = i - 1;

			break;

		case 'p':	/* The locale's equivalent of AM/PM. */

			LEGAL_ALT(0);

			/* AM? */

			if (strcasecmp(am_pm[0], bp) == 0) {

				if (tm->tm_hour > 11)

					return (0);

				bp += strlen(am_pm[0]);

				break;

			}

			/* PM? */

			else if (strcasecmp(am_pm[1], bp) == 0) {

				if (tm->tm_hour > 11)

					return (0);

				tm->tm_hour += 12;

				bp += strlen(am_pm[1]);

				break;

			}

			/* Nothing matched. */

			return (0);

		case 'S':	/* The seconds. */

			LEGAL_ALT(ALT_O);

			if (!(conv_num(&bp, &tm->tm_sec, 0, 61)))

				return (0);

			break;

		case 'U':	/* The week of year, beginning on sunday. */

		case 'W':	/* The week of year, beginning on monday. */

			LEGAL_ALT(ALT_O);

			/*

			 * XXX This is bogus, as we can not assume any valid

			 * information present in the tm structure at this

			 * point to calculate a real value, so just check the

			 * range for now.

			 */

			 if (!(conv_num(&bp, &i, 0, 53)))

				return (0);

			 break;

		case 'w':	/* The day of week, beginning on sunday. */

			LEGAL_ALT(ALT_O);

			if (!(conv_num(&bp, &tm->tm_wday, 0, 6)))

				return (0);

			break;

		case 'Y':	/* The year. */

			LEGAL_ALT(ALT_E);

			if (!(conv_num(&bp, &i, 0, 9999)))

				return (0);

			tm->tm_year = i - TM_YEAR_BASE;

			break;

		case 'y':	/* The year within 100 years of the epoch. */

			LEGAL_ALT(ALT_E | ALT_O);

			if (!(conv_num(&bp, &i, 0, 99)))

				return (0);

			if (split_year) {

				tm->tm_year = ((tm->tm_year / 100) * 100) + i;

				break;

			}

			split_year = 1;

			if (i <= 68)

				tm->tm_year = i + 2000 - TM_YEAR_BASE;

			else

				tm->tm_year = i + 1900 - TM_YEAR_BASE;

			break;

		/*

		 * Miscellaneous conversions.

		 */

		case 'n':	/* Any kind of white-space. */

		case 't':

			LEGAL_ALT(0);

			while (isspace((unsigned char) *bp))

				bp++;

			break;

		default:	/* Unknown/unsupported conversion. */

			return (0);

		}

	}

	/* LINTED functional specification */

	DE_CONST(bp, ret);

	return (ret);

}