Commit c05b7fdf authored by Rémi Denis-Courmont's avatar Rémi Denis-Courmont

gmtime_r: rewrite, now truly thread-safe

parent c086f181
/*****************************************************************************
* gmtime_r.c: POSIX gmtime_r() replacement
*****************************************************************************
* Copyright © 1998-2008 VLC authors and VideoLAN
* Copyright © 2011-2012 Rémi Denis-Courmont
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
......@@ -23,13 +23,73 @@
#endif
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
struct tm *gmtime_r (const time_t *timep, struct tm *result)
struct tm *gmtime_r (const time_t *timep, struct tm *tm)
{
struct tm *s = gmtime (timep);
if (s == NULL)
return NULL;
static const unsigned short normal[12] =
{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
static const unsigned short leap[12] =
{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
lldiv_t d;
const unsigned short *months;
*result = *s;
return result;
/* Rebase from 1970 Unix epoch to fictitious year 0 (i.e. would-be
* year 1 BC had the Gregorian calendar already existed then) */
d.quot = 60LL * 60 * 24 * (4 * 146097 + 135140) + *timep;
d = lldiv (d.quot, 60); /* 60 seconds per minute */
if (*timep < 0)
{
d.rem += 60;
d.quot--;
}
tm->tm_sec = d.rem;
d = lldiv (d.quot, 60); /* 60 minutes per hour */
tm->tm_min = d.rem;
d = lldiv (d.quot, 24); /* 24 hours per day */
tm->tm_hour = d.rem;
tm->tm_wday = (d.quot + 6) % 7; /* 7 days per week */
d = lldiv (d.quot, 146097); /* 146097 days per 4 centuries */
tm->tm_year = 400 * d.quot;
if (d.rem >= 36525)
{ /* Century with 24 leap years */
d.rem -= 36525;
tm->tm_year += 100;
d = lldiv (d.rem, 36524); /* 36524 days per normal century */
tm->tm_year += d.quot * 100;
if (d.rem >= 59) /* not in January or February of year 00 */
d.rem++; /* insert missing February 29th 00*/
}
tm->tm_year -= 1900; /* Rebase to 1900 for struct tm */
d = lldiv (d.rem, 1461); /* 1461 days per 4 years */
tm->tm_year += 4 * d.quot;
if (d.rem >= 366)
{ /* Non-leap year */
d.rem -= 366;
tm->tm_year++;
d = lldiv (d.rem, 365); /* 365 days per normal year */
tm->tm_year += d.quot;
months = normal;
}
else
months = leap;
tm->tm_yday = d.rem;
for (tm->tm_mon = 0; d.rem >= months[tm->tm_mon]; tm->tm_mon++)
d.rem -= months[tm->tm_mon]; /* 28 to 31 days in a month */
tm->tm_mday = d.rem + 1;
tm->tm_isdst = 0; /* UTC time */
return tm;
}
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