glibc/time/tzfile.c
1995-02-18 01:27:10 +00:00

333 lines
7.9 KiB
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/* Copyright (C) 1991, 1992, 1993 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., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <ansidecl.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <string.h>
#include <limits.h>
#define NOID
#include <tzfile.h>
#ifndef HAVE_GNU_LD
#define __tzname tzname
#define __daylight daylight
#define __timezone timezone
#endif
int __use_tzfile = 0;
struct ttinfo
{
long int offset; /* Seconds east of GMT. */
unsigned char isdst; /* Used to set tm_isdst. */
unsigned char idx; /* Index into `zone_names'. */
unsigned char isstd; /* Transition times are standard time. */
};
struct leap
{
time_t transition; /* Time the transition takes effect. */
long int change; /* Seconds of correction to apply. */
};
static void compute_tzname_max __P ((size_t));
static size_t num_transitions;
static time_t *transitions = NULL;
static unsigned char *type_idxs = NULL;
static size_t num_types;
static struct ttinfo *types = NULL;
static char *zone_names = NULL;
static size_t num_leaps;
static struct leap *leaps = NULL;
#define uc2ul(x) _uc2ul((unsigned char *) (x))
#define _uc2ul(x) \
((x)[3] + ((x)[2] << CHAR_BIT) + ((x)[1] << (2 * CHAR_BIT)) + \
((x)[0] << (3 * CHAR_BIT)))
void
DEFUN(__tzfile_read, (file), CONST char *file)
{
size_t num_isstd;
register FILE *f;
struct tzhead tzhead;
size_t chars;
register size_t i;
__use_tzfile = 0;
if (transitions != NULL)
free((PTR) transitions);
transitions = NULL;
if (type_idxs != NULL)
free((PTR) type_idxs);
type_idxs = NULL;
if (types != NULL)
free((PTR) types);
types = NULL;
if (zone_names != NULL)
free((PTR) zone_names);
zone_names = NULL;
if (leaps != NULL)
free((PTR) leaps);
leaps = NULL;
if (file == NULL || *file == '\0')
file = TZDEFAULT;
if (*file != '/')
{
static CONST char tzdir[] = TZDIR;
register CONST unsigned int len = strlen(file) + 1;
char *new = (char *) __alloca(sizeof(tzdir) + len);
memcpy(new, tzdir, sizeof(tzdir) - 1);
new[sizeof(tzdir) - 1] = '/';
memcpy(&new[sizeof(tzdir)], file, len);
file = new;
}
f = fopen(file, "r");
if (f == NULL)
return;
if (fread((PTR) &tzhead, sizeof(tzhead), 1, f) != 1)
goto lose;
num_transitions = (size_t) uc2ul(tzhead.tzh_timecnt);
num_types = (size_t) uc2ul(tzhead.tzh_typecnt);
chars = (size_t) uc2ul(tzhead.tzh_charcnt);
num_leaps = (size_t) uc2ul(tzhead.tzh_leapcnt);
num_isstd = (size_t) uc2ul(tzhead.tzh_ttisstdcnt);
if (num_transitions > 0)
{
transitions = (time_t *) malloc (num_transitions * sizeof(time_t));
if (transitions == NULL)
goto lose;
type_idxs = (unsigned char *) malloc (num_transitions);
if (type_idxs == NULL)
goto lose;
}
if (num_types > 0)
{
types = (struct ttinfo *) malloc (num_types * sizeof (struct ttinfo));
if (types == NULL)
goto lose;
}
if (chars > 0)
{
zone_names = (char *) malloc (chars);
if (zone_names == NULL)
goto lose;
}
if (num_leaps > 0)
{
leaps = (struct leap *) malloc (num_leaps * sizeof (struct leap));
if (leaps == NULL)
goto lose;
}
if (fread((PTR) transitions, sizeof(time_t),
num_transitions, f) != num_transitions ||
fread((PTR) type_idxs, 1, num_transitions, f) != num_transitions)
goto lose;
for (i = 0; i < num_transitions; ++i)
transitions[i] = uc2ul (&transitions[i]);
for (i = 0; i < num_types; ++i)
{
unsigned char x[4];
if (fread((PTR) x, 1, 4, f) != 4 ||
fread((PTR) &types[i].isdst, 1, 1, f) != 1 ||
fread((PTR) &types[i].idx, 1, 1, f) != 1)
goto lose;
types[i].offset = (long int) uc2ul(x);
}
if (fread((PTR) zone_names, 1, chars, f) != chars)
goto lose;
for (i = 0; i < num_leaps; ++i)
{
unsigned char x[4];
if (fread((PTR) x, 1, sizeof(x), f) != sizeof(x))
goto lose;
leaps[i].transition = (time_t) uc2ul(x);
if (fread((PTR) x, 1, sizeof(x), f) != sizeof(x))
goto lose;
leaps[i].change = (long int) uc2ul(x);
}
for (i = 0; i < num_isstd; ++i)
{
char c = getc(f);
if (c == EOF)
goto lose;
types[i].isstd = c != 0;
}
while (i < num_types)
types[i++].isstd = 0;
(void) fclose(f);
compute_tzname_max (chars);
__use_tzfile = 1;
return;
lose:;
(void) fclose(f);
}
void
DEFUN(__tzfile_default, (std, dst, stdoff, dstoff),
char *std AND char *dst AND
long int stdoff AND long int dstoff)
{
size_t stdlen, dstlen, i;
__tzfile_read (TZDEFRULES);
if (!__use_tzfile)
return;
if (num_types < 2)
{
__use_tzfile = 0;
return;
}
free (zone_names);
stdlen = strlen (std) + 1;
dstlen = strlen (dst) + 1;
zone_names = malloc (stdlen + dstlen);
if (zone_names == NULL)
{
__use_tzfile = 0;
return;
}
memcpy (zone_names, std, stdlen);
memcpy (&zone_names[stdlen], dst, dstlen);
for (i = 0; i < num_types; ++i)
if (types[i].isdst)
{
types[i].idx = stdlen;
if (dst[0] != '\0')
types[i].offset = dstoff;
}
else
{
types[i].idx = 0;
if (dst[0] != '\0')
types[i].offset = stdoff;
}
compute_tzname_max (stdlen + dstlen);
}
int
DEFUN(__tzfile_compute, (timer, leap_correct, leap_hit),
time_t timer AND long int *leap_correct AND int *leap_hit)
{
struct ttinfo *info;
register size_t i;
if (num_transitions == 0 || timer < transitions[0])
{
/* TIMER is before any transition (or there are no transitions).
Choose the first non-DST type
(or the first if they're all DST types). */
i = 0;
while (i < num_types && types[i].isdst)
++i;
if (i == num_types)
i = 0;
}
else
{
/* Find the first transition after TIMER, and
then pick the type of the transition before it. */
for (i = 1; i < num_transitions; ++i)
if (timer < transitions[i])
break;
i = type_idxs[i - 1];
}
info = &types[i];
__daylight = info->isdst;
__timezone = info->offset;
for (i = 0; i < num_types && i < sizeof (__tzname) / sizeof (__tzname[0]);
++i)
__tzname[types[i].isdst] = &zone_names[types[i].idx];
if (info->isdst < sizeof (__tzname) / sizeof (__tzname[0]))
__tzname[info->isdst] = &zone_names[info->idx];
*leap_correct = 0L;
*leap_hit = 0;
/* Find the last leap second correction transition time before TIMER. */
i = num_leaps;
do
if (i-- == 0)
return 1;
while (timer < leaps[i].transition);
/* Apply its correction. */
*leap_correct = leaps[i].change;
if (timer == leaps[i].transition && /* Exactly at the transition time. */
((i == 0 && leaps[i].change > 0) ||
leaps[i].change > leaps[i - 1].change))
{
*leap_hit = 1;
while (i > 0 &&
leaps[i].transition == leaps[i - 1].transition + 1 &&
leaps[i].change == leaps[i - 1].change + 1)
{
++*leap_hit;
--i;
}
}
return 1;
}
void
DEFUN(compute_tzname_max, (chars), size_t chars)
{
extern long int __tzname_cur_max; /* Defined in __tzset.c. */
const char *p;
p = zone_names;
do
{
const char *start = p;
while (*p != '\0')
++p;
if (p - start > __tzname_cur_max)
__tzname_cur_max = p - start;
} while (++p < &zone_names[chars]);
}