/*
* Copyright © 2010 Codethink Limited
*
* This 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 of the licence, or (at your option) any later version.
*
* This 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 this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
* Author: Ryan Lortie <desrt@desrt.ca>
*/
/* Prologue {{{1 */
#include "gtimezone.h"
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include "gmappedfile.h"
#include "gtestutils.h"
#include "gfileutils.h"
#include "gstrfuncs.h"
#include "ghash.h"
#include "gthread.h"
#include "gbytes.h"
#include "gslice.h"
/**
* SECTION:timezone
* @title: GTimeZone
* @short_description: a structure representing a time zone
* @see_also: #GDateTime
*
* #GTimeZone is a structure that represents a time zone, at no
* particular point in time. It is refcounted and immutable.
*
* A time zone contains a number of intervals. Each interval has
* an abbreviation to describe it, an offet to UTC and a flag indicating
* if the daylight savings time is in effect during that interval. A
* time zone always has at least one interval -- interval 0.
*
* Every UTC time is contained within exactly one interval, but a given
* local time may be contained within zero, one or two intervals (due to
* incontinuities associated with daylight savings time).
*
* An interval may refer to a specific period of time (eg: the duration
* of daylight savings time during 2010) or it may refer to many periods
* of time that share the same properties (eg: all periods of daylight
* savings time). It is also possible (usually for political reasons)
* that some properties (like the abbreviation) change between intervals
* without other properties changing.
*
* #GTimeZone is available since GLib 2.26.
*/
/**
* GTimeZone:
*
* #GDateTime is an opaque structure whose members cannot be accessed
* directly.
*
* Since: 2.26
**/
/* zoneinfo file format {{{1 */
/* unaligned */
typedef struct { gchar bytes[8]; } gint64_be;
typedef struct { gchar bytes[4]; } gint32_be;
typedef struct { gchar bytes[4]; } guint32_be;
static inline gint64 gint64_from_be (const gint64_be be) {
gint64 tmp; memcpy (&tmp, &be, sizeof tmp); return GINT64_FROM_BE (tmp);
}
static inline gint32 gint32_from_be (const gint32_be be) {
gint32 tmp; memcpy (&tmp, &be, sizeof tmp); return GINT32_FROM_BE (tmp);
}
static inline guint32 guint32_from_be (const guint32_be be) {
guint32 tmp; memcpy (&tmp, &be, sizeof tmp); return GUINT32_FROM_BE (tmp);
}
struct tzhead
{
gchar tzh_magic[4];
gchar tzh_version;
guchar tzh_reserved[15];
guint32_be tzh_ttisgmtcnt;
guint32_be tzh_ttisstdcnt;
guint32_be tzh_leapcnt;
guint32_be tzh_timecnt;
guint32_be tzh_typecnt;
guint32_be tzh_charcnt;
};
struct ttinfo
{
gint32_be tt_gmtoff;
guint8 tt_isdst;
guint8 tt_abbrind;
};
/* GTimeZone structure and lifecycle {{{1 */
struct _GTimeZone
{
gchar *name;
GBytes *zoneinfo;
const struct tzhead *header;
const struct ttinfo *infos;
const gint64_be *trans;
const guint8 *indices;
const gchar *abbrs;
gint timecnt;
gint ref_count;
};
G_LOCK_DEFINE_STATIC (time_zones);
static GHashTable/*<string?, GTimeZone>*/ *time_zones;
/**
* g_time_zone_unref:
* @tz: a #GTimeZone
*
* Decreases the reference count on @tz.
*
* Since: 2.26
**/
void
g_time_zone_unref (GTimeZone *tz)
{
int ref_count;
again:
ref_count = g_atomic_int_get (&tz->ref_count);
g_assert (ref_count > 0);
if (ref_count == 1)
{
if (tz->name != NULL)
{
G_LOCK(time_zones);
/* someone else might have grabbed a ref in the meantime */
if G_UNLIKELY (g_atomic_int_get (&tz->ref_count) != 1)
{
G_UNLOCK(time_zones);
goto again;
}
g_hash_table_remove (time_zones, tz->name);
G_UNLOCK(time_zones);
}
if (tz->zoneinfo)
g_bytes_unref (tz->zoneinfo);
g_free (tz->name);
g_slice_free (GTimeZone, tz);
}
else if G_UNLIKELY (!g_atomic_int_compare_and_exchange (&tz->ref_count,
ref_count,
ref_count - 1))
goto again;
}
/**
* g_time_zone_ref:
* @tz: a #GTimeZone
*
* Increases the reference count on @tz.
*
* Returns: a new reference to @tz.
*
* Since: 2.26
**/
GTimeZone *
g_time_zone_ref (GTimeZone *tz)
{
g_assert (tz->ref_count > 0);
g_atomic_int_inc (&tz->ref_count);
return tz;
}
/* fake zoneinfo creation (for RFC3339/ISO 8601 timezones) {{{1 */
/*
* parses strings of the form 'hh' 'hhmm' or 'hh:mm' where:
* - hh is 00 to 23
* - mm is 00 to 59
*/
static gboolean
parse_time (const gchar *time_,
gint32 *offset)
{
if (*time_ < '0' || '2' < *time_)
return FALSE;
*offset = 10 * 60 * 60 * (*time_++ - '0');
if (*time_ < '0' || '9' < *time_)
return FALSE;
*offset += 60 * 60 * (*time_++ - '0');
if (*offset > 23 * 60 * 60)
return FALSE;
if (*time_ == '\0')
return TRUE;
if (*time_ == ':')
time_++;
if (*time_ < '0' || '5' < *time_)
return FALSE;
*offset += 10 * 60 * (*time_++ - '0');
if (*time_ < '0' || '9' < *time_)
return FALSE;
*offset += 60 * (*time_++ - '0');
return *time_ == '\0';
}
static gboolean
parse_constant_offset (const gchar *name,
gint32 *offset)
{
switch (*name++)
{
case 'Z':
*offset = 0;
return !*name;
case '+':
return parse_time (name, offset);
case '-':
if (parse_time (name, offset))
{
*offset = -*offset;
return TRUE;
}
default:
return FALSE;
}
}
static GBytes *
zone_for_constant_offset (const gchar *name)
{
const gchar fake_zoneinfo_headers[] =
"TZif" "2..." "...." "...." "...."
"\0\0\0\0" "\0\0\0\0" "\0\0\0\0" "\0\0\0\0" "\0\0\0\0" "\0\0\0\0"
"TZif" "2..." "...." "...." "...."
"\0\0\0\0" "\0\0\0\0" "\0\0\0\0" "\0\0\0\0" "\0\0\0\1" "\0\0\0\7";
struct {
struct tzhead headers[2];
struct ttinfo info;
gchar abbr[8];
} *fake;
gint32 offset;
if (name == NULL || !parse_constant_offset (name, &offset))
return NULL;
offset = GINT32_TO_BE (offset);
fake = g_malloc (sizeof *fake);
memcpy (fake, fake_zoneinfo_headers, sizeof fake_zoneinfo_headers);
memcpy (&fake->info.tt_gmtoff, &offset, sizeof offset);
fake->info.tt_isdst = FALSE;
fake->info.tt_abbrind = 0;
strcpy (fake->abbr, name);
return g_bytes_new_take (fake, sizeof *fake);
}
/* Construction {{{1 */
/**
* g_time_zone_new:
* @identifier: (allow-none): a timezone identifier
*
* Creates a #GTimeZone corresponding to @identifier.
*
* @identifier can either be an RFC3339/ISO 8601 time offset or
* something that would pass as a valid value for the
* <varname>TZ</varname> environment variable (including %NULL).
*
* Valid RFC3339 time offsets are <literal>"Z"</literal> (for UTC) or
* <literal>"±hh:mm"</literal>. ISO 8601 additionally specifies
* <literal>"±hhmm"</literal> and <literal>"±hh"</literal>.
*
* The <varname>TZ</varname> environment variable typically corresponds
* to the name of a file in the zoneinfo database, but there are many
* other possibilities. Note that those other possibilities are not
* currently implemented, but are planned.
*
* g_time_zone_new_local() calls this function with the value of the
* <varname>TZ</varname> environment variable. This function itself is
* independent of the value of <varname>TZ</varname>, but if @identifier
* is %NULL then <filename>/etc/localtime</filename> will be consulted
* to discover the correct timezone.
*
* See <ulink
* url='http://tools.ietf.org/html/rfc3339#section-5.6'>RFC3339
* §5.6</ulink> for a precise definition of valid RFC3339 time offsets
* (the <varname>time-offset</varname> expansion) and ISO 8601 for the
* full list of valid time offsets. See <ulink
* url='http://www.gnu.org/s/libc/manual/html_node/TZ-Variable.html'>The
* GNU C Library manual</ulink> for an explanation of the possible
* values of the <varname>TZ</varname> environment variable.
*
* You should release the return value by calling g_time_zone_unref()
* when you are done with it.
*
* Returns: the requested timezone
*
* Since: 2.26
**/
GTimeZone *
g_time_zone_new (const gchar *identifier)
{
GTimeZone *tz;
GMappedFile *file;
G_LOCK (time_zones);
if (time_zones == NULL)
time_zones = g_hash_table_new (g_str_hash, g_str_equal);
if (identifier)
tz = g_hash_table_lookup (time_zones, identifier);
else
tz = NULL;
if (tz == NULL)
{
tz = g_slice_new0 (GTimeZone);
tz->name = g_strdup (identifier);
tz->ref_count = 0;
tz->zoneinfo = zone_for_constant_offset (identifier);
if (tz->zoneinfo == NULL)
{
gchar *filename;
/* identifier can be a relative or absolute path name;
if relative, it is interpreted starting from /usr/share/timezone
while the POSIX standard says it should start with :,
glibc allows both syntaxes, so we should too */
if (identifier != NULL)
{
const gchar *tzdir;
tzdir = getenv ("TZDIR");
if (tzdir == NULL)
tzdir = "/usr/share/zoneinfo";
if (*identifier == ':')
identifier ++;
if (g_path_is_absolute (identifier))
filename = g_strdup (identifier);
else
filename = g_build_filename (tzdir, identifier, NULL);
}
else
filename = g_strdup ("/etc/localtime");
file = g_mapped_file_new (filename, FALSE, NULL);
if (file != NULL)
{
tz->zoneinfo = g_bytes_new_with_free_func (g_mapped_file_get_contents (file),
g_mapped_file_get_length (file),
(GDestroyNotify)g_mapped_file_unref,
g_mapped_file_ref (file));
g_mapped_file_unref (file);
}
g_free (filename);
}
if (tz->zoneinfo != NULL)
{
gsize size;
const struct tzhead *header = g_bytes_get_data (tz->zoneinfo, &size);
/* we only bother to support version 2 */
if (size < sizeof (struct tzhead) || memcmp (header, "TZif2", 5))
{
g_bytes_unref (tz->zoneinfo);
tz->zoneinfo = NULL;
}
else
{
gint typecnt;
/* we trust the file completely. */
tz->header = (const struct tzhead *)
(((const gchar *) (header + 1)) +
guint32_from_be(header->tzh_ttisgmtcnt) +
guint32_from_be(header->tzh_ttisstdcnt) +
8 * guint32_from_be(header->tzh_leapcnt) +
5 * guint32_from_be(header->tzh_timecnt) +
6 * guint32_from_be(header->tzh_typecnt) +
guint32_from_be(header->tzh_charcnt));
typecnt = guint32_from_be (tz->header->tzh_typecnt);
tz->timecnt = guint32_from_be (tz->header->tzh_timecnt);
tz->trans = (gconstpointer) (tz->header + 1);
tz->indices = (gconstpointer) (tz->trans + tz->timecnt);
tz->infos = (gconstpointer) (tz->indices + tz->timecnt);
tz->abbrs = (gconstpointer) (tz->infos + typecnt);
}
}
if (identifier)
g_hash_table_insert (time_zones, tz->name, tz);
}
g_atomic_int_inc (&tz->ref_count);
G_UNLOCK (time_zones);
return tz;
}
/**
* g_time_zone_new_utc:
*
* Creates a #GTimeZone corresponding to UTC.
*
* This is equivalent to calling g_time_zone_new() with a value like
* "Z", "UTC", "+00", etc.
*
* You should release the return value by calling g_time_zone_unref()
* when you are done with it.
*
* Returns: the universal timezone
*
* Since: 2.26
**/
GTimeZone *
g_time_zone_new_utc (void)
{
return g_time_zone_new ("UTC");
}
/**
* g_time_zone_new_local:
*
* Creates a #GTimeZone corresponding to local time. The local time
* zone may change between invocations to this function; for example,
* if the system administrator changes it.
*
* This is equivalent to calling g_time_zone_new() with the value of the
* <varname>TZ</varname> environment variable (including the possibility
* of %NULL).
*
* You should release the return value by calling g_time_zone_unref()
* when you are done with it.
*
* Returns: the local timezone
*
* Since: 2.26
**/
GTimeZone *
g_time_zone_new_local (void)
{
return g_time_zone_new (getenv ("TZ"));
}
/* Internal helpers {{{1 */
inline static const struct ttinfo *
interval_info (GTimeZone *tz,
gint interval)
{
if (interval)
return tz->infos + tz->indices[interval - 1];
return tz->infos;
}
inline static gint64
interval_start (GTimeZone *tz,
gint interval)
{
if (interval)
return gint64_from_be (tz->trans[interval - 1]);
return G_MININT64;
}
inline static gint64
interval_end (GTimeZone *tz,
gint interval)
{
if (interval < tz->timecnt)
return gint64_from_be (tz->trans[interval]) - 1;
return G_MAXINT64;
}
inline static gint32
interval_offset (GTimeZone *tz,
gint interval)
{
return gint32_from_be (interval_info (tz, interval)->tt_gmtoff);
}
inline static gboolean
interval_isdst (GTimeZone *tz,
gint interval)
{
return interval_info (tz, interval)->tt_isdst;
}
inline static guint8
interval_abbrind (GTimeZone *tz,
gint interval)
{
return interval_info (tz, interval)->tt_abbrind;
}
inline static gint64
interval_local_start (GTimeZone *tz,
gint interval)
{
if (interval)
return interval_start (tz, interval) + interval_offset (tz, interval);
return G_MININT64;
}
inline static gint64
interval_local_end (GTimeZone *tz,
gint interval)
{
if (interval < tz->timecnt)
return interval_end (tz, interval) + interval_offset (tz, interval);
return G_MAXINT64;
}
static gboolean
interval_valid (GTimeZone *tz,
gint interval)
{
return interval <= tz->timecnt;
}
/* g_time_zone_find_interval() {{{1 */
/**
* g_time_zone_adjust_time:
* @tz: a #GTimeZone
* @type: the #GTimeType of @time_
* @time_: a pointer to a number of seconds since January 1, 1970
*
* Finds an interval within @tz that corresponds to the given @time_,
* possibly adjusting @time_ if required to fit into an interval.
* The meaning of @time_ depends on @type.
*
* This function is similar to g_time_zone_find_interval(), with the
* difference that it always succeeds (by making the adjustments
* described below).
*
* In any of the cases where g_time_zone_find_interval() succeeds then
* this function returns the same value, without modifying @time_.
*
* This function may, however, modify @time_ in order to deal with
* non-existent times. If the non-existent local @time_ of 02:30 were
* requested on March 14th 2010 in Toronto then this function would
* adjust @time_ to be 03:00 and return the interval containing the
* adjusted time.
*
* Returns: the interval containing @time_, never -1
*
* Since: 2.26
**/
gint
g_time_zone_adjust_time (GTimeZone *tz,
GTimeType type,
gint64 *time_)
{
gint i;
if (tz->zoneinfo == NULL)
return 0;
/* find the interval containing *time UTC
* TODO: this could be binary searched (or better) */
for (i = 0; i < tz->timecnt; i++)
if (*time_ <= interval_end (tz, i))
break;
g_assert (interval_start (tz, i) <= *time_ && *time_ <= interval_end (tz, i));
if (type != G_TIME_TYPE_UNIVERSAL)
{
if (*time_ < interval_local_start (tz, i))
/* if time came before the start of this interval... */
{
i--;
/* if it's not in the previous interval... */
if (*time_ > interval_local_end (tz, i))
{
/* it doesn't exist. fast-forward it. */
i++;
*time_ = interval_local_start (tz, i);
}
}
else if (*time_ > interval_local_end (tz, i))
/* if time came after the end of this interval... */
{
i++;
/* if it's not in the next interval... */
if (*time_ < interval_local_start (tz, i))
/* it doesn't exist. fast-forward it. */
*time_ = interval_local_start (tz, i);
}
else if (interval_isdst (tz, i) != type)
/* it's in this interval, but dst flag doesn't match.
* check neighbours for a better fit. */
{
if (i && *time_ <= interval_local_end (tz, i - 1))
i--;
else if (i < tz->timecnt &&
*time_ >= interval_local_start (tz, i + 1))
i++;
}
}
return i;
}
/**
* g_time_zone_find_interval:
* @tz: a #GTimeZone
* @type: the #GTimeType of @time_
* @time_: a number of seconds since January 1, 1970
*
* Finds an the interval within @tz that corresponds to the given @time_.
* The meaning of @time_ depends on @type.
*
* If @type is %G_TIME_TYPE_UNIVERSAL then this function will always
* succeed (since universal time is monotonic and continuous).
*
* Otherwise @time_ is treated is local time. The distinction between
* %G_TIME_TYPE_STANDARD and %G_TIME_TYPE_DAYLIGHT is ignored except in
* the case that the given @time_ is ambiguous. In Toronto, for example,
* 01:30 on November 7th 2010 occurred twice (once inside of daylight
* savings time and the next, an hour later, outside of daylight savings
* time). In this case, the different value of @type would result in a
* different interval being returned.
*
* It is still possible for this function to fail. In Toronto, for
* example, 02:00 on March 14th 2010 does not exist (due to the leap
* forward to begin daylight savings time). -1 is returned in that
* case.
*
* Returns: the interval containing @time_, or -1 in case of failure
*
* Since: 2.26
*/
gint
g_time_zone_find_interval (GTimeZone *tz,
GTimeType type,
gint64 time_)
{
gint i;
if (tz->zoneinfo == NULL)
return 0;
for (i = 0; i < tz->timecnt; i++)
if (time_ <= interval_end (tz, i))
break;
if (type == G_TIME_TYPE_UNIVERSAL)
return i;
if (time_ < interval_local_start (tz, i))
{
if (time_ > interval_local_end (tz, --i))
return -1;
}
else if (time_ > interval_local_end (tz, i))
{
if (time_ < interval_local_start (tz, ++i))
return -1;
}
else if (interval_isdst (tz, i) != type)
{
if (i && time_ <= interval_local_end (tz, i - 1))
i--;
else if (i < tz->timecnt && time_ >= interval_local_start (tz, i + 1))
i++;
}
return i;
}
/* Public API accessors {{{1 */
/**
* g_time_zone_get_abbreviation:
* @tz: a #GTimeZone
* @interval: an interval within the timezone
*
* Determines the time zone abbreviation to be used during a particular
* @interval of time in the time zone @tz.
*
* For example, in Toronto this is currently "EST" during the winter
* months and "EDT" during the summer months when daylight savings time
* is in effect.
*
* Returns: the time zone abbreviation, which belongs to @tz
*
* Since: 2.26
**/
const gchar *
g_time_zone_get_abbreviation (GTimeZone *tz,
gint interval)
{
g_return_val_if_fail (interval_valid (tz, interval), NULL);
if (tz->header == NULL)
return "UTC";
return tz->abbrs + interval_abbrind (tz, interval);
}
/**
* g_time_zone_get_offset:
* @tz: a #GTimeZone
* @interval: an interval within the timezone
*
* Determines the offset to UTC in effect during a particular @interval
* of time in the time zone @tz.
*
* The offset is the number of seconds that you add to UTC time to
* arrive at local time for @tz (ie: negative numbers for time zones
* west of GMT, positive numbers for east).
*
* Returns: the number of seconds that should be added to UTC to get the
* local time in @tz
*
* Since: 2.26
**/
gint32
g_time_zone_get_offset (GTimeZone *tz,
gint interval)
{
g_return_val_if_fail (interval_valid (tz, interval), 0);
if (tz->header == NULL)
return 0;
return interval_offset (tz, interval);
}
/**
* g_time_zone_is_dst:
* @tz: a #GTimeZone
* @interval: an interval within the timezone
*
* Determines if daylight savings time is in effect during a particular
* @interval of time in the time zone @tz.
*
* Returns: %TRUE if daylight savings time is in effect
*
* Since: 2.26
**/
gboolean
g_time_zone_is_dst (GTimeZone *tz,
gint interval)
{
g_return_val_if_fail (interval_valid (tz, interval), FALSE);
if (tz->header == NULL)
return FALSE;
return interval_isdst (tz, interval);
}
/* Epilogue {{{1 */
/* vim:set foldmethod=marker: */