shadow/libmisc/strtoday.c

/*
 * SPDX-FileCopyrightText: 1991 - 1994, Julianne Frances Haugh
 * SPDX-FileCopyrightText: 1996 - 1999, Marek Michałkiewicz
 * SPDX-FileCopyrightText: 2003 - 2005, Tomasz Kłoczko
 * SPDX-FileCopyrightText: 2008       , Nicolas François
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <config.h>

#include <ctype.h>

#ident "$Id$"

#include "defines.h"
#include "prototypes.h"

#ifndef USE_GETDATE
#define USE_GETDATE 1
#endif

#if USE_GETDATE
#include "getdate.h"
/*
 * strtoday() now uses get_date() (borrowed from GNU shellutils)
 * which can handle many date formats, for example:
 *	1970-09-17	# ISO 8601.
 *	70-9-17		# This century assumed by default.
 *	70-09-17	# Leading zeros are ignored.
 *	9/17/72		# Common U.S. writing.
 *	24 September 1972
 *	24 Sept 72	# September has a special abbreviation.
 *	24 Sep 72	# Three-letter abbreviations always allowed.
 *	Sep 24, 1972
 *	24-sep-72
 *	24sep72
 */
long strtoday (const char *str)
{
	time_t t;
	bool isnum = true;
	const char *s = str;

	/*
	 * get_date() interprets an empty string as the current date,
	 * which is not what we expect, unless you're a BOFH :-).
	 * (useradd sets sp_expire = current date for new lusers)
	 */
	if ((NULL == str) || ('\0' == *str)) {
		return -1;
	}

	/* If a numerical value is provided, this is already a number of
	 * days since EPOCH.
	 */
	if ('-' == *s) {
		s++;
	}
	while (' ' == *s) {
		s++;
	}
	while (isnum && ('\0' != *s)) {
		if (!isdigit (*s)) {
			isnum = false;
		}
		s++;
	}
	if (isnum) {
		long retdate;
		if (getlong (str, &retdate) == 0) {
			return -2;
		}
		return retdate;
	}

	t = get_date (str, NULL);
	if ((time_t) - 1 == t) {
		return -2;
	}
	/* convert seconds to days since 1970-01-01 */
	return (long) (t + DAY / 2) / DAY;
}

#else				/* !USE_GETDATE */
/*
 * Old code, just in case get_date() doesn't work as expected...
 */
#include <stdio.h>
#ifdef HAVE_STRPTIME
/*
 * for now we allow just one format, but we can define more later
 * (we try them all until one succeeds).  --marekm
 */
static const char *const date_formats[] = {
	"%Y-%m-%d",
	(char *) 0
};
#else
/*
 * days and juldays are used to compute the number of days in the
 * current month, and the cumulative number of days in the preceding
 * months.  they are declared so that january is 1, not 0.
 */
static const short days[13] = { 0,
	31, 28, 31, 30, 31, 30,	/* JAN - JUN */
	31, 31, 30, 31, 30, 31
};				/* JUL - DEC */

static const short juldays[13] = { 0,
	0, 31, 59, 90, 120, 151,	/* JAN - JUN */
	181, 212, 243, 273, 304, 334
};				/* JUL - DEC */
#endif

/*
 * strtoday - compute the number of days since 1970.
 *
 * the total number of days prior to the current date is
 * computed.  january 1, 1970 is used as the origin with
 * it having a day number of 0.
 */

long strtoday (const char *str)
{
#ifdef HAVE_STRPTIME
	struct tm tp;
	const char *const *fmt;
	char *cp;
	time_t result;

	memzero (&tp, sizeof tp);
	for (fmt = date_formats; *fmt; fmt++) {
		cp = strptime ((char *) str, *fmt, &tp);
		if ((NULL == cp) || ('\0' != *cp)) {
			continue;
		}

		result = mktime (&tp);
		if ((time_t) - 1 == result) {
			continue;
		}

		return (long) (result / DAY);	/* success */
	}
	return -1;
#else
	char slop[2];
	int month;
	int day;
	int year;
	long total;

	/*
	 * start by separating the month, day and year.  the order
	 * is compiled in ...
	 */

	if (sscanf (str, "%d/%d/%d%c", &year, &month, &day, slop) != 3) {
		return -1;
	}

	/*
	 * the month, day of the month, and year are checked for
	 * correctness and the year adjusted so it falls between
	 * 1970 and 2069.
	 */

	if ((month < 1) || (month > 12)) {
		return -1;
	}

	if (day < 1) {
		return -1;
	}

	if (   ((2 != month) || ((year % 4) != 0))
	    && (day > days[month])) {
		return -1;
	} else if ((month == 2) && ((year % 4) == 0) && (day > 29)) {
		return -1;
	}

	if (year < 0) {
		return -1;
	} else if (year <= 69) {
		year += 2000;
	} else if (year <= 99) {
		year += 1900;
	}

	/*
	 * On systems with 32-bit signed time_t, time wraps around in 2038
	 * - for now we just limit the year to 2037 (instead of 2069).
	 * This limit can be removed once no one is using 32-bit systems
	 * anymore :-).  --marekm
	 */
	if ((year < 1970) || (year > 2037)) {
		return -1;
	}

	/*
	 * the total number of days is the total number of days in all
	 * the whole years, plus the number of leap days, plus the
	 * number of days in the whole months preceding, plus the number
	 * of days so far in the month.
	 */

	total = (long) ((year - 1970) * 365L) + (((year + 1) - 1970) / 4);
	total += (long) juldays[month] + (month > 2 && (year % 4) == 0 ? 1 : 0);
	total += (long) day - 1;

	return total;
#endif				/* HAVE_STRPTIME */
}
#endif				/* !USE_GETDATE */