sudo/lib/util/timegm.c

100 lines
2.4 KiB
C

/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2017, 2021 Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#ifndef HAVE_TIMEGM
#include <stdio.h>
#include <time.h>
#include <sudo_compat.h>
#include <sudo_debug.h>
/*
* Returns the offset from GMT in seconds (algorithm taken from sendmail).
*/
#ifdef HAVE_STRUCT_TM_TM_GMTOFF
static long
get_gmtoff(time_t *when)
{
struct tm local;
if (localtime_r(when, &local) == NULL)
return 0;
/* Adjust for DST. */
if (local.tm_isdst != 0)
local.tm_gmtoff -= local.tm_isdst * 3600;
return local.tm_gmtoff;
}
#else
static long
get_gmtoff(time_t *when)
{
struct tm gmt, local;
long offset;
if (gmtime_r(when, &gmt) == NULL)
return 0;
if (localtime_r(when, &local) == NULL)
return 0;
offset = (local.tm_sec - gmt.tm_sec) +
((local.tm_min - gmt.tm_min) * 60) +
((local.tm_hour - gmt.tm_hour) * 3600);
/* Timezone may cause year rollover to happen on a different day. */
if (local.tm_year < gmt.tm_year)
offset -= 24 * 3600;
else if (local.tm_year > gmt.tm_year)
offset -= 24 * 3600;
else if (local.tm_yday < gmt.tm_yday)
offset -= 24 * 3600;
else if (local.tm_yday > gmt.tm_yday)
offset += 24 * 3600;
/* Adjust for DST. */
if (local.tm_isdst != 0)
offset -= local.tm_isdst * 3600;
return offset;
}
#endif /* HAVE_TM_GMTOFF */
time_t
sudo_timegm(struct tm *tm)
{
time_t result;
tm->tm_isdst = 0;
result = mktime(tm);
if (result != -1)
result += get_gmtoff(&result);
return result;
}
#endif /* HAVE_TIMEGM */