glibc/time/localtime.c
1997-01-06 22:07:28 +00:00

123 lines
3.2 KiB
C

/* Convert `time_t' to `struct tm' in local time zone.
Copyright (C) 1991, 92, 93, 95, 96, 97 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <errno.h>
#include <time.h>
#include <libc-lock.h>
/* The C Standard says that localtime and gmtime return the same pointer. */
struct tm _tmbuf;
/* Prototype for the internal function to get information based on TZ. */
extern void __tzset_internal __P ((int always));
extern int __tz_compute __P ((time_t timer, struct tm *tp));
extern int __tzfile_compute __P ((time_t timer,
long int *leap_correct, int *leap_hit));
extern int __use_tzfile;
/* This lock is defined in tzset.c and locks all the data defined there
and in tzfile.c; the internal functions do no locking themselves.
This lock is only taken here and in `tzset'. */
__libc_lock_define (extern, __tzset_lock)
/* Return the `struct tm' representation of *TIMER in the local timezone. */
static struct tm *
localtime_internal (const time_t *timer, struct tm *tp)
{
long int leap_correction;
int leap_extra_secs;
if (timer == NULL)
{
__set_errno (EINVAL);
return NULL;
}
if (__use_tzfile)
{
if (! __tzfile_compute (*timer, &leap_correction, &leap_extra_secs))
tp = NULL;
}
else
{
tp = __gmtime_r (timer, tp);
if (tp && ! __tz_compute (*timer, tp))
tp = NULL;
leap_correction = 0L;
leap_extra_secs = 0;
}
if (tp)
{
__offtime (timer, __timezone - leap_correction, tp);
tp->tm_sec += leap_extra_secs;
tp->tm_isdst = __daylight;
tp->tm_gmtoff = __timezone;
tp->tm_zone = __tzname[__daylight];
}
return tp;
}
/* POSIX.1 8.3.7.2 says that localtime_r is not required to set
tzname. This is a good idea since this allows at least a bit more
parallelism. */
struct tm *
localtime (timer)
const time_t *timer;
{
struct tm *result;
__libc_lock_lock (__tzset_lock);
/* Update internal database according to current TZ setting. */
__tzset_internal (1);
result = localtime_internal (timer, &_tmbuf);
__libc_lock_unlock (__tzset_lock);
return result;
}
struct tm *
__localtime_r (timer, tp)
const time_t *timer;
struct tm *tp;
{
struct tm *result;
__libc_lock_lock (__tzset_lock);
/* Make sure the database is initialized. */
__tzset_internal (0);
result = localtime_internal (timer, tp);
__libc_lock_unlock (__tzset_lock);
return result;
}
weak_alias (__localtime_r, localtime_r)