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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* This code placed in the public domain by Mark W. Eichin */
#include <stdio.h>
#include "autoconf.h"
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#ifdef TIME_WITH_SYS_TIME
#include <time.h>
#endif
#else
#include <time.h>
#endif
#include "k5-gmt_mktime.h"
#if !HAVE_TIMEGM || TEST_LEAP
static time_t gmt_mktime(struct tm *t);
#endif
/*
* Use the nonstandard timegm() (if available) to convert broken-down
* UTC times into time_t values. Use our custom gmt_mktime() if
* timegm() is not available.
*
* We use gmtime() (or gmtime_r()) when encoding ASN.1 GeneralizedTime
* values. On systems where a "right" (leap-second-aware) time zone
* is configured, gmtime() adjusts for the presence of accumulated
* leap seconds in the input time_t value. POSIX requires that time_t
* values omit leap seconds; systems configured to include leap
* seconds in their time_t values are non-conforming and will have
* difficulties exchanging timestamp information with other systems.
*
* We use krb5int_gmt_mktime() for decoding ASN.1 GeneralizedTime
* values. If timegm() is not available, krb5int_gmt_mktime() won't
* be the inverse of gmtime() on a system that counts leap seconds. A
* system configured with a "right" time zone probably has timegm()
* available; without it, an application would have no reliable way of
* converting broken-down UTC times into time_t values.
*/
time_t
krb5int_gmt_mktime(struct tm *t)
{
#if HAVE_TIMEGM
return timegm(t);
#else
return gmt_mktime(t);
#endif
}
#if !HAVE_TIMEGM || TEST_LEAP
/* take a struct tm, return seconds from GMT epoch */
/* like mktime, this ignores tm_wday and tm_yday. */
/* unlike mktime, this does not set them... it only passes a return value. */
static const int days_in_month[12] = {
0, /* jan 31 */
31, /* feb 28 */
59, /* mar 31 */
90, /* apr 30 */
120, /* may 31 */
151, /* jun 30 */
181, /* jul 31 */
212, /* aug 31 */
243, /* sep 30 */
273, /* oct 31 */
304, /* nov 30 */
334 /* dec 31 */
};
#define hasleapday(year) (year%400?(year%100?(year%4?0:1):0):1)
static time_t
gmt_mktime(struct tm *t)
{
time_t accum;
#define assert_time(cnd) if(!(cnd)) return (time_t) -1
/*
* For 32-bit signed time_t centered on 1/1/1970, the range is:
* time 0x80000000 -> Fri Dec 13 16:45:52 1901
* time 0x7fffffff -> Mon Jan 18 22:14:07 2038
*
* So years 1901 and 2038 are allowable, but we can't encode all
* dates in those years, and we're not doing overflow/underflow
* checking for such cases.
*/
assert_time(t->tm_year>=1);
assert_time(t->tm_year<=138);
assert_time(t->tm_mon>=0);
assert_time(t->tm_mon<=11);
assert_time(t->tm_mday>=1);
assert_time(t->tm_mday<=31);
assert_time(t->tm_hour>=0);
assert_time(t->tm_hour<=23);
assert_time(t->tm_min>=0);
assert_time(t->tm_min<=59);
assert_time(t->tm_sec>=0);
assert_time(t->tm_sec<=62);
#undef assert_time
accum = t->tm_year - 70;
accum *= 365; /* 365 days/normal year */
/* add in leap day for all previous years */
if (t->tm_year >= 70)
accum += (t->tm_year - 69) / 4;
else
accum -= (72 - t->tm_year) / 4;
/* add in leap day for this year */
if(t->tm_mon >= 2) /* march or later */
if(hasleapday((t->tm_year + 1900))) accum += 1;
accum += days_in_month[t->tm_mon];
accum += t->tm_mday-1; /* days of month are the only 1-based field */
accum *= 24; /* 24 hour/day */
accum += t->tm_hour;
accum *= 60; /* 60 minute/hour */
accum += t->tm_min;
accum *= 60; /* 60 seconds/minute */
accum += t->tm_sec;
return accum;
}
#endif /* !HAVE_TIMEGM || TEST_LEAP */
#ifdef TEST_LEAP
int
main (int argc, char *argv[])
{
int yr;
time_t t;
struct tm tm = {
.tm_mon = 0, .tm_mday = 1,
.tm_hour = 0, .tm_min = 0, .tm_sec = 0,
};
for (yr = 60; yr <= 104; yr++)
{
printf ("1/1/%d%c -> ", 1900 + yr, hasleapday((1900+yr)) ? '*' : ' ');
tm.tm_year = yr;
t = gmt_mktime (&tm);
if (t == (time_t) -1)
printf ("-1\n");
else
{
long u;
if (t % (24 * 60 * 60))
printf ("(not integral multiple of days) ");
u = t / (24 * 60 * 60);
printf ("%3ld*365%+ld\t0x%08lx\n",
(long) (u / 365), (long) (u % 365),
(long) t);
}
}
t = 0x80000000, printf ("time 0x%lx -> %s", t, ctime (&t));
t = 0x7fffffff, printf ("time 0x%lx -> %s", t, ctime (&t));
return 0;
}
#endif
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