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/* last-time.c: Part of GNU CSSC.
*
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007,
* 2008, 2009, 2010, 2001, 2014, 2019 Free Software Foundation, Inc.
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*
*
* This program is not installed as part of CSSC. It's just desinged
* to help you figure out the year-2038 date at which your C library
* gives out.
*
* No attempt has been made to make this program use the
* Autoconf-generated configuration information.
*/
#include <config.h>
#include <stdio.h>
#include <time.h>
static int*
next_field(struct tm *ptm,
int *current)
{
int *next;
if (current == &ptm->tm_year)
next = &ptm->tm_mon;
else if (current == &ptm->tm_mon)
next = &ptm->tm_mday;
else if (current == &ptm->tm_mday)
next = &ptm->tm_hour;
else if (current == &ptm->tm_hour)
next = &ptm->tm_min;
else if (current == &ptm->tm_min)
next = &ptm->tm_sec;
else
next = NULL;
return next;
}
int main()
{
struct tm tm_time;
struct tm *ptm;
time_t now;
time_t then;
long maxiters = 2000L;
int *pfield;
int old_field_val;
tm_time.tm_year = 97; /* 1997 */
tm_time.tm_mon = 0; /* counts from zero for some reason. */
tm_time.tm_mday = 1;
tm_time.tm_hour = 0;
tm_time.tm_min = 0;
tm_time.tm_sec = 0;
tm_time.tm_isdst = -1;
ptm = &tm_time;
pfield = &ptm->tm_year;
old_field_val = *pfield;
while (maxiters--)
{
now = mktime(ptm);
if ( (time_t)-1 == then )
{
perror("mktime error");
exit(1);
}
else if (difftime(now, then) < 0.0)
{
*pfield = old_field_val;
pfield = next_field(ptm, pfield);
if (NULL == pfield)
{
/* Print the "final" time */
printf("%s", ctime(&then));
exit(0); /* done. */
}
}
else
{
then = now;
}
old_field_val = *pfield;
++*pfield;
}
printf("The time representation doesn't seem to"
" break very easily; is this a 64-bit system (or more)?\n");
exit(0); /* this can happen too. */
}
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