/* Copyright (C) 1991-2018 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 Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <ctype.h>
#include <errno.h>
#include <libc-lock.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <timezone/tzfile.h>
#define SECSPERDAY ((time_t) 86400)
char *__tzname[2] = { (char *) "GMT", (char *) "GMT" };
int __daylight = 0;
long int __timezone = 0L;
weak_alias (__tzname, tzname)
weak_alias (__daylight, daylight)
weak_alias (__timezone, timezone)
/* This locks all the state variables in tzfile.c and this file. */
__libc_lock_define_initialized (static, tzset_lock)
/* This structure contains all the information about a
timezone given in the POSIX standard TZ envariable. */
typedef struct
{
const char *name;
/* When to change. */
enum { J0, J1, M } type; /* Interpretation of: */
unsigned short int m, n, d; /* Month, week, day. */
int secs; /* Time of day. */
long int offset; /* Seconds east of GMT (west if < 0). */
/* We cache the computed time of change for a
given year so we don't have to recompute it. */
time_t change; /* When to change to this zone. */
int computed_for; /* Year above is computed for. */
} tz_rule;
/* tz_rules[0] is standard, tz_rules[1] is daylight. */
static tz_rule tz_rules[2];
static void compute_change (tz_rule *rule, int year) __THROW;
static void tzset_internal (int always);
/* List of buffers containing time zone strings. */
struct tzstring_l
{
struct tzstring_l *next;
size_t len; /* strlen(data) - doesn't count terminating NUL! */
char data[0];
};
static struct tzstring_l *tzstring_list;
/* Allocate a permanent home for the first LEN characters of S. It
will never be moved or deallocated, but may share space with other
strings. Don't modify the returned string. */
static char *
__tzstring_len (const char *s, size_t len)
{
char *p;
struct tzstring_l *t, *u, *new;
/* Walk the list and look for a match. If this string is the same
as the end of an already-allocated string, it can share space. */
for (u = t = tzstring_list; t; u = t, t = t->next)
if (len <= t->len)
{
p = &t->data[t->len - len];
if (memcmp (s, p, len) == 0)
return p;
}
/* Not found; allocate a new buffer. */
new = malloc (sizeof (struct tzstring_l) + len + 1);
if (!new)
return NULL;
new->next = NULL;
new->len = len;
memcpy (new->data, s, len);
new->data[len] = '\0';
if (u)
u->next = new;
else
tzstring_list = new;
return new->data;
}
/* Allocate a permanent home for S. It will never be moved or
deallocated, but may share space with other strings. Don't modify
the returned string. */
char *
__tzstring (const char *s)
{
return __tzstring_len (s, strlen (s));
}
static char *old_tz;
static void
update_vars (void)
{
__daylight = tz_rules[0].offset != tz_rules[1].offset;
__timezone = -tz_rules[0].offset;
__tzname[0] = (char *) tz_rules[0].name;
__tzname[1] = (char *) tz_rules[1].name;
}
static unsigned int
compute_offset (unsigned int ss, unsigned int mm, unsigned int hh)
{
if (ss > 59)
ss = 59;
if (mm > 59)
mm = 59;
if (hh > 24)
hh = 24;
return ss + mm * 60 + hh * 60 * 60;
}
/* Parses the time zone name at *TZP, and writes a pointer to an
interned string to tz_rules[WHICHRULE].name. On success, advances
*TZP, and returns true. Returns false otherwise. */
static bool
parse_tzname (const char **tzp, int whichrule)
{
const char *start = *tzp;
const char *p = start;
while (('a' <= *p && *p <= 'z')
|| ('A' <= *p && *p <= 'Z'))
++p;
size_t len = p - start;
if (len < 3)
{
p = *tzp;
if (__glibc_unlikely (*p++ != '<'))
return false;
start = p;
while (('a' <= *p && *p <= 'z')
|| ('A' <= *p && *p <= 'Z')
|| ('0' <= *p && *p <= '9')
|| *p == '+' || *p == '-')
++p;
len = p - start;
if (*p++ != '>' || len < 3)
return false;
}
const char *name = __tzstring_len (start, len);
if (name == NULL)
return false;
tz_rules[whichrule].name = name;
*tzp = p;
return true;
}
/* Parses the time zone offset at *TZP, and writes it to
tz_rules[WHICHRULE].offset. Returns true if the parse was
successful. */
static bool
parse_offset (const char **tzp, int whichrule)
{
const char *tz = *tzp;
if (whichrule == 0
&& (*tz == '\0' || (*tz != '+' && *tz != '-' && !isdigit (*tz))))
return false;
long sign;
if (*tz == '-' || *tz == '+')
sign = *tz++ == '-' ? 1L : -1L;
else
sign = -1L;
*tzp = tz;
unsigned short int hh;
unsigned short mm = 0;
unsigned short ss = 0;
int consumed = 0;
if (sscanf (tz, "%hu%n:%hu%n:%hu%n",
&hh, &consumed, &mm, &consumed, &ss, &consumed) > 0)
tz_rules[whichrule].offset = sign * compute_offset (ss, mm, hh);
else
/* Nothing could be parsed. */
if (whichrule == 0)
{
/* Standard time defaults to offset zero. */
tz_rules[0].offset = 0;
return false;
}
else
/* DST defaults to one hour later than standard time. */
tz_rules[1].offset = tz_rules[0].offset + (60 * 60);
*tzp = tz + consumed;
return true;
}
/* Parses the standard <-> DST rules at *TZP. Updates
tz_rule[WHICHRULE]. On success, advances *TZP and returns true.
Otherwise, returns false. */
static bool
parse_rule (const char **tzp, int whichrule)
{
const char *tz = *tzp;
tz_rule *tzr = &tz_rules[whichrule];
/* Ignore comma to support string following the incorrect
specification in early POSIX.1 printings. */
tz += *tz == ',';
/* Get the date of the change. */
if (*tz == 'J' || isdigit (*tz))
{
char *end;
tzr->type = *tz == 'J' ? J1 : J0;
if (tzr->type == J1 && !isdigit (*++tz))
return false;
unsigned long int d = strtoul (tz, &end, 10);
if (end == tz || d > 365)
return false;
if (tzr->type == J1 && d == 0)
return false;
tzr->d = d;
tz = end;
}
else if (*tz == 'M')
{
tzr->type = M;
int consumed;
if (sscanf (tz, "M%hu.%hu.%hu%n",
&tzr->m, &tzr->n, &tzr->d, &consumed) != 3
|| tzr->m < 1 || tzr->m > 12
|| tzr->n < 1 || tzr->n > 5 || tzr->d > 6)
return false;
tz += consumed;
}
else if (*tz == '\0')
{
/* Daylight time rules in the U.S. are defined in the U.S. Code,
Title 15, Chapter 6, Subchapter IX - Standard Time. These
dates were established by Congress in the Energy Policy Act
of 2005 [Pub. L. no. 109-58, 119 Stat 594 (2005)].
Below is the equivalent of "M3.2.0,M11.1.0" [/2 not needed
since 2:00AM is the default]. */
tzr->type = M;
if (tzr == &tz_rules[0])
{
tzr->m = 3;
tzr->n = 2;
tzr->d = 0;
}
else
{
tzr->m = 11;
tzr->n = 1;
tzr->d = 0;
}
}
else
return false;
if (*tz != '\0' && *tz != '/' && *tz != ',')
return false;
else if (*tz == '/')
{
/* Get the time of day of the change. */
int negative;
++tz;
if (*tz == '\0')
return false;
negative = *tz == '-';
tz += negative;
/* Default to 2:00 AM. */
unsigned short hh = 2;
unsigned short mm = 0;
unsigned short ss = 0;
int consumed = 0;
sscanf (tz, "%hu%n:%hu%n:%hu%n",
&hh, &consumed, &mm, &consumed, &ss, &consumed);;
tz += consumed;
tzr->secs = (negative ? -1 : 1) * ((hh * 60 * 60) + (mm * 60) + ss);
}
else
/* Default to 2:00 AM. */
tzr->secs = 2 * 60 * 60;
tzr->computed_for = -1;
*tzp = tz;
return true;
}
/* Parse the POSIX TZ-style string. */
void
__tzset_parse_tz (const char *tz)
{
/* Clear out old state and reset to unnamed UTC. */
memset (tz_rules, '\0', sizeof tz_rules);
tz_rules[0].name = tz_rules[1].name = "";
/* Get the standard timezone name. */
if (parse_tzname (&tz, 0) && parse_offset (&tz, 0))
{
/* Get the DST timezone name (if any). */
if (*tz != '\0')
{
if (parse_tzname (&tz, 1))
{
parse_offset (&tz, 1);
if (*tz == '\0' || (tz[0] == ',' && tz[1] == '\0'))
{
/* There is no rule. See if there is a default rule
file. */
__tzfile_default (tz_rules[0].name, tz_rules[1].name,
tz_rules[0].offset, tz_rules[1].offset);
if (__use_tzfile)
{
free (old_tz);
old_tz = NULL;
return;
}
}
}
/* Figure out the standard <-> DST rules. */
if (parse_rule (&tz, 0))
parse_rule (&tz, 1);
}
else
{
/* There is no DST. */
tz_rules[1].name = tz_rules[0].name;
tz_rules[1].offset = tz_rules[0].offset;
}
}
update_vars ();
}
/* Interpret the TZ envariable. */
static void
tzset_internal (int always)
{
static int is_initialized;
const char *tz;
if (is_initialized && !always)
return;
is_initialized = 1;
/* Examine the TZ environment variable. */
tz = getenv ("TZ");
if (tz && *tz == '\0')
/* User specified the empty string; use UTC explicitly. */
tz = "Universal";
/* A leading colon means "implementation defined syntax".
We ignore the colon and always use the same algorithm:
try a data file, and if none exists parse the 1003.1 syntax. */
if (tz && *tz == ':')
++tz;
/* Check whether the value changed since the last run. */
if (old_tz != NULL && tz != NULL && strcmp (tz, old_tz) == 0)
/* No change, simply return. */
return;
if (tz == NULL)
/* No user specification; use the site-wide default. */
tz = TZDEFAULT;
tz_rules[0].name = NULL;
tz_rules[1].name = NULL;
/* Save the value of `tz'. */
free (old_tz);
old_tz = tz ? __strdup (tz) : NULL;
/* Try to read a data file. */
__tzfile_read (tz, 0, NULL);
if (__use_tzfile)
return;
/* No data file found. Default to UTC if nothing specified. */
if (tz == NULL || *tz == '\0'
|| (TZDEFAULT != NULL && strcmp (tz, TZDEFAULT) == 0))
{
memset (tz_rules, '\0', sizeof tz_rules);
tz_rules[0].name = tz_rules[1].name = "UTC";
if (J0 != 0)
tz_rules[0].type = tz_rules[1].type = J0;
tz_rules[0].change = tz_rules[1].change = (time_t) -1;
update_vars ();
return;
}
__tzset_parse_tz (tz);
}
/* Figure out the exact time (as a time_t) in YEAR
when the change described by RULE will occur and
put it in RULE->change, saving YEAR in RULE->computed_for. */
static void
compute_change (tz_rule *rule, int year)
{
time_t t;
if (year != -1 && rule->computed_for == year)
/* Operations on times in 2 BC will be slower. Oh well. */
return;
/* First set T to January 1st, 0:00:00 GMT in YEAR. */
if (year > 1970)
t = ((year - 1970) * 365
+ /* Compute the number of leapdays between 1970 and YEAR
(exclusive). There is a leapday every 4th year ... */
+ ((year - 1) / 4 - 1970 / 4)
/* ... except every 100th year ... */
- ((year - 1) / 100 - 1970 / 100)
/* ... but still every 400th year. */
+ ((year - 1) / 400 - 1970 / 400)) * SECSPERDAY;
else
t = 0;
switch (rule->type)
{
case J1:
/* Jn - Julian day, 1 == January 1, 60 == March 1 even in leap years.
In non-leap years, or if the day number is 59 or less, just
add SECSPERDAY times the day number-1 to the time of
January 1, midnight, to get the day. */
t += (rule->d - 1) * SECSPERDAY;
if (rule->d >= 60 && __isleap (year))
t += SECSPERDAY;
break;
case J0:
/* n - Day of year.
Just add SECSPERDAY times the day number to the time of Jan 1st. */
t += rule->d * SECSPERDAY;
break;
case M:
/* Mm.n.d - Nth "Dth day" of month M. */
{
unsigned int i;
int d, m1, yy0, yy1, yy2, dow;
const unsigned short int *myday =
&__mon_yday[__isleap (year)][rule->m];
/* First add SECSPERDAY for each day in months before M. */
t += myday[-1] * SECSPERDAY;
/* Use Zeller's Congruence to get day-of-week of first day of month. */
m1 = (rule->m + 9) % 12 + 1;
yy0 = (rule->m <= 2) ? (year - 1) : year;
yy1 = yy0 / 100;
yy2 = yy0 % 100;
dow = ((26 * m1 - 2) / 10 + 1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
if (dow < 0)
dow += 7;
/* DOW is the day-of-week of the first day of the month. Get the
day-of-month (zero-origin) of the first DOW day of the month. */
d = rule->d - dow;
if (d < 0)
d += 7;
for (i = 1; i < rule->n; ++i)
{
if (d + 7 >= (int) myday[0] - myday[-1])
break;
d += 7;
}
/* D is the day-of-month (zero-origin) of the day we want. */
t += d * SECSPERDAY;
}
break;
}
/* T is now the Epoch-relative time of 0:00:00 GMT on the day we want.
Just add the time of day and local offset from GMT, and we're done. */
rule->change = t - rule->offset + rule->secs;
rule->computed_for = year;
}
/* Figure out the correct timezone for TM and set `__tzname',
`__timezone', and `__daylight' accordingly. */
void
__tz_compute (time_t timer, struct tm *tm, int use_localtime)
{
compute_change (&tz_rules[0], 1900 + tm->tm_year);
compute_change (&tz_rules[1], 1900 + tm->tm_year);
if (use_localtime)
{
int isdst;
/* We have to distinguish between northern and southern
hemisphere. For the latter the daylight saving time
ends in the next year. */
if (__builtin_expect (tz_rules[0].change
> tz_rules[1].change, 0))
isdst = (timer < tz_rules[1].change
|| timer >= tz_rules[0].change);
else
isdst = (timer >= tz_rules[0].change
&& timer < tz_rules[1].change);
tm->tm_isdst = isdst;
tm->tm_zone = __tzname[isdst];
tm->tm_gmtoff = tz_rules[isdst].offset;
}
}
/* Reinterpret the TZ environment variable and set `tzname'. */
#undef tzset
void
__tzset (void)
{
__libc_lock_lock (tzset_lock);
tzset_internal (1);
if (!__use_tzfile)
{
/* Set `tzname'. */
__tzname[0] = (char *) tz_rules[0].name;
__tzname[1] = (char *) tz_rules[1].name;
}
__libc_lock_unlock (tzset_lock);
}
weak_alias (__tzset, tzset)
/* Return the `struct tm' representation of *TIMER in the local timezone.
Use local time if USE_LOCALTIME is nonzero, UTC otherwise. */
struct tm *
__tz_convert (const time_t *timer, int use_localtime, struct tm *tp)
{
long int leap_correction;
int leap_extra_secs;
if (timer == NULL)
{
__set_errno (EINVAL);
return NULL;
}
__libc_lock_lock (tzset_lock);
/* Update internal database according to current TZ setting.
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. */
tzset_internal (tp == &_tmbuf && use_localtime);
if (__use_tzfile)
__tzfile_compute (*timer, use_localtime, &leap_correction,
&leap_extra_secs, tp);
else
{
if (! __offtime (timer, 0, tp))
tp = NULL;
else
__tz_compute (*timer, tp, use_localtime);
leap_correction = 0L;
leap_extra_secs = 0;
}
__libc_lock_unlock (tzset_lock);
if (tp)
{
if (! use_localtime)
{
tp->tm_isdst = 0;
tp->tm_zone = "GMT";
tp->tm_gmtoff = 0L;
}
if (__offtime (timer, tp->tm_gmtoff - leap_correction, tp))
tp->tm_sec += leap_extra_secs;
else
tp = NULL;
}
return tp;
}
libc_freeres_fn (free_mem)
{
while (tzstring_list != NULL)
{
struct tzstring_l *old = tzstring_list;
tzstring_list = tzstring_list->next;
free (old);
}
free (old_tz);
old_tz = NULL;
}