gmtoff.c   [plain text]

/*
 * SPDX-License-Identifier: ISC
 *
 * Copyright (c) 2017 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>

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#include "sudo_compat.h"
#include "sudoers_debug.h"
#include "parse.h"

/*
 * Returns the offset from GMT in seconds (algorithm taken from sendmail).
 * Warning: clobbers the static storage used by localtime() and gmtime().
 */
#ifdef HAVE_STRUCT_TM_TM_GMTOFF
long
get_gmtoff(time_t *clock)
{
	struct tm *local;

	local = localtime(clock);
	return local->tm_gmtoff;
}
#else
long
get_gmtoff(time_t *clock)
{
	struct tm *gm, gmt, *local;
	long offset;

	if ((gm = gmtime(clock)) == NULL)
	    return 0;
	gmt = *gm;
	if ((local = localtime(clock)) == 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;

	return offset;
}
#endif /* HAVE_TM_GMTOFF */