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/*
* Copyright (C) 1996-2000 Michael R. Elkins <me@mutt.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include "mutt.h"
#include <string.h>
/* returns the seconds east of UTC given `g' and its corresponding gmtime()
representation */
static time_t compute_tz (time_t g, struct tm *utc)
{
struct tm *lt = localtime (&g);
time_t t;
int yday;
t = (((lt->tm_hour - utc->tm_hour) * 60) + (lt->tm_min - utc->tm_min)) * 60;
if ((yday = (lt->tm_yday - utc->tm_yday)))
{
/* This code is optimized to negative timezones (West of Greenwich) */
if (yday == -1 || /* UTC passed midnight before localtime */
yday > 1) /* UTC passed new year before localtime */
t -= 24 * 60 * 60;
else
t += 24 * 60 * 60;
}
return t;
}
/* Returns the local timezone in seconds east of UTC for the time t,
* or for the current time if t is zero.
*/
time_t mutt_local_tz (time_t t)
{
struct tm *ptm;
struct tm utc;
if (!t)
t = time (NULL);
ptm = gmtime (&t);
/* need to make a copy because gmtime/localtime return a pointer to
static memory (grr!) */
memcpy (&utc, ptm, sizeof (utc));
return (compute_tz (t, &utc));
}
/* theoretically time_t can be float but it is integer on most (if not all) systems */
#define TIME_T_MAX ((((time_t) 1 << (sizeof(time_t) * 8 - 2)) - 1) * 2 + 1)
#define TM_YEAR_MAX (1970 + (((((TIME_T_MAX - 59) / 60) - 59) / 60) - 23) / 24 / 366)
/* converts struct tm to time_t, but does not take the local timezone into
account unless ``local'' is nonzero */
time_t mutt_mktime (struct tm *t, int local)
{
time_t g;
static const int AccumDaysPerMonth[12] = {
0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
};
/* Prevent an integer overflow.
* The time_t cast is an attempt to silence a clang range warning. */
if ((time_t)t->tm_year > TM_YEAR_MAX)
return TIME_T_MAX;
/* Compute the number of days since January 1 in the same year */
g = AccumDaysPerMonth [t->tm_mon % 12];
/* The leap years are 1972 and every 4. year until 2096,
* but this algorithm will fail after year 2099 */
g += t->tm_mday;
if ((t->tm_year % 4) || t->tm_mon < 2)
g--;
t->tm_yday = g;
/* Compute the number of days since January 1, 1970 */
g += (t->tm_year - 70) * (time_t)365;
g += (t->tm_year - 69) / 4;
/* Compute the number of hours */
g *= 24;
g += t->tm_hour;
/* Compute the number of minutes */
g *= 60;
g += t->tm_min;
/* Compute the number of seconds */
g *= 60;
g += t->tm_sec;
if (local)
g -= compute_tz (g, t);
return (g);
}
/* Return 1 if month is February of leap year, else 0 */
static int isLeapYearFeb (struct tm *tm)
{
if (tm->tm_mon == 1)
{
int y = tm->tm_year + 1900;
return (((y & 3) == 0) && (((y % 100) != 0) || ((y % 400) == 0)));
}
return (0);
}
void mutt_normalize_time (struct tm *tm)
{
static const char DaysPerMonth[12] = {
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
int nLeap;
while (tm->tm_sec < 0)
{
tm->tm_sec += 60;
tm->tm_min--;
}
while (tm->tm_sec >= 60)
{
tm->tm_sec -= 60;
tm->tm_min++;
}
while (tm->tm_min < 0)
{
tm->tm_min += 60;
tm->tm_hour--;
}
while (tm->tm_min >= 60)
{
tm->tm_min -= 60;
tm->tm_hour++;
}
while (tm->tm_hour < 0)
{
tm->tm_hour += 24;
tm->tm_mday--;
}
while (tm->tm_hour >= 24)
{
tm->tm_hour -= 24;
tm->tm_mday++;
}
/* use loops on NNNdwmy user input values? */
while (tm->tm_mon < 0)
{
tm->tm_mon += 12;
tm->tm_year--;
}
while (tm->tm_mon >= 12)
{
tm->tm_mon -= 12;
tm->tm_year++;
}
while (tm->tm_mday <= 0)
{
if (tm->tm_mon)
tm->tm_mon--;
else
{
tm->tm_mon = 11;
tm->tm_year--;
}
tm->tm_mday += DaysPerMonth[tm->tm_mon] + isLeapYearFeb (tm);
}
while (tm->tm_mday > (DaysPerMonth[tm->tm_mon] +
(nLeap = isLeapYearFeb (tm))))
{
tm->tm_mday -= DaysPerMonth[tm->tm_mon] + nLeap;
if (tm->tm_mon < 11)
tm->tm_mon++;
else
{
tm->tm_mon = 0;
tm->tm_year++;
}
}
}
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