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glib/glib/gtimezone.c
Paul Eggert 137dd7789b gtimezone: port to tzcode 2014c 
Problem reported by Marien Zwart in:
https://gitlab.gnome.org/GNOME/glib/issues/878
Derived from a fix by John Ralls proposed in that bug report.
2018-06-11 14:30:16 +01:00

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/*
* 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 2.1 of the License, 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, see <http://www.gnu.org/licenses/>.
*
* Author: Ryan Lortie <desrt@desrt.ca>
*/
/* Prologue {{{1 */
#include "config.h"
#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"
#include "gdatetime.h"
#include "gdate.h"
#ifdef G_OS_WIN32
#define STRICT
#include <windows.h>
#endif
/**
* 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.
*
* Each time zone has an identifier (for example, ‘Europe/London’) which is
* platform dependent. See g_time_zone_new() for information on the identifier
* formats. The identifier of a time zone can be retrieved using
* g_time_zone_get_identifier().
*
* A time zone contains a number of intervals. Each interval has
* an abbreviation to describe it (for example, ‘PDT’), 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. Note
* that interval abbreviations are not the same as time zone identifiers
* (apart from ‘UTC’), and cannot be passed to g_time_zone_new().
*
* 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:
*
* #GTimeZone is an opaque structure whose members cannot be accessed
* directly.
*
* Since: 2.26
**/
/* IANA 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);
}
/* The layout of an IANA timezone file header */
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;
};
/* A Transition Date structure for TZ Rules, an intermediate structure
for parsing MSWindows and Environment-variable time zones. It
Generalizes MSWindows's SYSTEMTIME struct.
*/
typedef struct
{
gint year;
gint mon;
gint mday;
gint wday;
gint week;
gint hour;
gint min;
gint sec;
} TimeZoneDate;
/* POSIX Timezone abbreviations are typically 3 or 4 characters, but
Microsoft uses 32-character names. We'll use one larger to ensure
we have room for the terminating \0.
*/
#define NAME_SIZE 33
/* A MSWindows-style time zone transition rule. Generalizes the
MSWindows TIME_ZONE_INFORMATION struct. Also used to compose time
zones from tzset-style identifiers.
*/
typedef struct
{
gint start_year;
gint32 std_offset;
gint32 dlt_offset;
TimeZoneDate dlt_start;
TimeZoneDate dlt_end;
gchar std_name[NAME_SIZE];
gchar dlt_name[NAME_SIZE];
} TimeZoneRule;
/* GTimeZone's internal representation of a Daylight Savings (Summer)
time interval.
*/
typedef struct
{
gint32 gmt_offset;
gboolean is_dst;
gchar *abbrev;
} TransitionInfo;
/* GTimeZone's representation of a transition time to or from Daylight
Savings (Summer) time and Standard time for the zone. */
typedef struct
{
gint64 time;
gint info_index;
} Transition;
/* GTimeZone structure */
struct _GTimeZone
{
gchar *name;
GArray *t_info; /* Array of TransitionInfo */
GArray *transitions; /* Array of Transition */
gint ref_count;
};
G_LOCK_DEFINE_STATIC (time_zones);
static GHashTable/*<string?, GTimeZone>*/ *time_zones;
#define MIN_TZYEAR 1916 /* Daylight Savings started in WWI */
#define MAX_TZYEAR 2999 /* And it's not likely ever to go away, but
there's no point in getting carried
away. */
/**
* 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->t_info != NULL)
{
gint idx;
for (idx = 0; idx < tz->t_info->len; idx++)
{
TransitionInfo *info = &g_array_index (tz->t_info, TransitionInfo, idx);
g_free (info->abbrev);
}
g_array_free (tz->t_info, TRUE);
}
if (tz->transitions != NULL)
g_array_free (tz->transitions, TRUE);
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 h or hh[[:]mm[[[:]ss]]] where:
* - h[h] is 0 to 23
* - mm is 00 to 59
* - ss is 00 to 59
*/
static gboolean
parse_time (const gchar *time_,
gint32 *offset)
{
if (*time_ < '0' || '9' < *time_)
return FALSE;
*offset = 60 * 60 * (*time_++ - '0');
if (*time_ == '\0')
return TRUE;
if (*time_ != ':')
{
if (*time_ < '0' || '9' < *time_)
return FALSE;
*offset *= 10;
*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');
if (*time_ == '\0')
return TRUE;
if (*time_ == ':')
time_++;
if (*time_ < '0' || '5' < *time_)
return FALSE;
*offset += 10 * (*time_++ - '0');
if (*time_ < '0' || '9' < *time_)
return FALSE;
*offset += *time_++ - '0';
return *time_ == '\0';
}
static gboolean
parse_constant_offset (const gchar *name,
gint32 *offset)
{
if (g_strcmp0 (name, "UTC") == 0)
{
*offset = 0;
return TRUE;
}
if (*name >= '0' && '9' >= *name)
return parse_time (name, 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 void
zone_for_constant_offset (GTimeZone *gtz, const gchar *name)
{
gint32 offset;
TransitionInfo info;
if (name == NULL || !parse_constant_offset (name, &offset))
return;
info.gmt_offset = offset;
info.is_dst = FALSE;
info.abbrev = g_strdup (name);
gtz->name = g_strdup (name);
gtz->t_info = g_array_sized_new (FALSE, TRUE, sizeof (TransitionInfo), 1);
g_array_append_val (gtz->t_info, info);
/* Constant offset, no transitions */
gtz->transitions = NULL;
}
#ifdef G_OS_UNIX
static GBytes*
zone_info_unix (const gchar *identifier,
gchar **out_identifier)
{
gchar *filename;
GMappedFile *file = NULL;
GBytes *zoneinfo = NULL;
gchar *resolved_identifier = NULL;
const gchar *tzdir;
tzdir = getenv ("TZDIR");
if (tzdir == NULL)
tzdir = "/usr/share/zoneinfo";
/* identifier can be a relative or absolute path name;
if relative, it is interpreted starting from /usr/share/zoneinfo
while the POSIX standard says it should start with :,
glibc allows both syntaxes, so we should too */
if (identifier != NULL)
{
resolved_identifier = g_strdup (identifier);
if (*identifier == ':')
identifier ++;
if (g_path_is_absolute (identifier))
filename = g_strdup (identifier);
else
filename = g_build_filename (tzdir, identifier, NULL);
}
else
{
gsize prefix_len = 0;
gchar *canonical_path = NULL;
GError *read_link_err = NULL;
filename = g_strdup ("/etc/localtime");
/* Resolve the actual timezone pointed to by /etc/localtime. */
resolved_identifier = g_file_read_link (filename, &read_link_err);
if (resolved_identifier == NULL)
{
gboolean not_a_symlink = g_error_matches (read_link_err,
G_FILE_ERROR,
G_FILE_ERROR_INVAL);
g_clear_error (&read_link_err);
/* Fallback to the content of /var/db/zoneinfo if /etc/localtime is
* not a symlink. This is where 'tzsetup' program on FreeBSD and
* DragonflyBSD stores the timezone chosen by the user. */
if (not_a_symlink && g_file_get_contents ("/var/db/zoneinfo",
&resolved_identifier,
NULL, NULL))
g_strchomp (resolved_identifier);
else
{
/* Error */
g_assert (resolved_identifier == NULL);
goto out;
}
}
else
{
/* Resolve relative path */
canonical_path = g_canonicalize_filename (resolved_identifier, "/etc");
g_free (resolved_identifier);
resolved_identifier = g_steal_pointer (&canonical_path);
}
/* Strip the prefix and slashes if possible. */
if (g_str_has_prefix (resolved_identifier, tzdir))
{
prefix_len = strlen (tzdir);
while (*(resolved_identifier + prefix_len) == '/')
prefix_len++;
}
if (prefix_len > 0)
memmove (resolved_identifier, resolved_identifier + prefix_len,
strlen (resolved_identifier) - prefix_len + 1 /* nul terminator */);
g_free (canonical_path);
}
file = g_mapped_file_new (filename, FALSE, NULL);
if (file != NULL)
{
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_assert (resolved_identifier != NULL);
out:
if (out_identifier != NULL)
*out_identifier = g_steal_pointer (&resolved_identifier);
g_free (resolved_identifier);
g_free (filename);
return zoneinfo;
}
static void
init_zone_from_iana_info (GTimeZone *gtz,
GBytes *zoneinfo,
gchar *identifier /* (transfer full) */)
{
gsize size;
guint index;
guint32 time_count, type_count;
guint8 *tz_transitions, *tz_type_index, *tz_ttinfo;
guint8 *tz_abbrs;
gsize timesize = sizeof (gint32);
const struct tzhead *header = g_bytes_get_data (zoneinfo, &size);
g_return_if_fail (size >= sizeof (struct tzhead) &&
memcmp (header, "TZif", 4) == 0);
if (header->tzh_version == '2')
{
/* Skip ahead to the newer 64-bit data if it's available. */
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));
timesize = sizeof (gint64);
}
time_count = guint32_from_be(header->tzh_timecnt);
type_count = guint32_from_be(header->tzh_typecnt);
tz_transitions = ((guint8 *) (header) + sizeof (*header));
tz_type_index = tz_transitions + timesize * time_count;
tz_ttinfo = tz_type_index + time_count;
tz_abbrs = tz_ttinfo + sizeof (struct ttinfo) * type_count;
gtz->name = g_steal_pointer (&identifier);
gtz->t_info = g_array_sized_new (FALSE, TRUE, sizeof (TransitionInfo),
type_count);
gtz->transitions = g_array_sized_new (FALSE, TRUE, sizeof (Transition),
time_count);
for (index = 0; index < type_count; index++)
{
TransitionInfo t_info;
struct ttinfo info = ((struct ttinfo*)tz_ttinfo)[index];
t_info.gmt_offset = gint32_from_be (info.tt_gmtoff);
t_info.is_dst = info.tt_isdst ? TRUE : FALSE;
t_info.abbrev = g_strdup ((gchar *) &tz_abbrs[info.tt_abbrind]);
g_array_append_val (gtz->t_info, t_info);
}
for (index = 0; index < time_count; index++)
{
Transition trans;
if (header->tzh_version == '2')
trans.time = gint64_from_be (((gint64_be*)tz_transitions)[index]);
else
trans.time = gint32_from_be (((gint32_be*)tz_transitions)[index]);
trans.info_index = tz_type_index[index];
g_assert (trans.info_index >= 0);
g_assert (trans.info_index < gtz->t_info->len);
g_array_append_val (gtz->transitions, trans);
}
}
#elif defined (G_OS_WIN32)
static void
copy_windows_systemtime (SYSTEMTIME *s_time, TimeZoneDate *tzdate)
{
tzdate->sec = s_time->wSecond;
tzdate->min = s_time->wMinute;
tzdate->hour = s_time->wHour;
tzdate->mon = s_time->wMonth;
tzdate->year = s_time->wYear;
tzdate->wday = s_time->wDayOfWeek ? s_time->wDayOfWeek : 7;
if (s_time->wYear)
{
tzdate->mday = s_time->wDay;
tzdate->wday = 0;
}
else
tzdate->week = s_time->wDay;
}
/* UTC = local time + bias while local time = UTC + offset */
static void
rule_from_windows_time_zone_info (TimeZoneRule *rule,
TIME_ZONE_INFORMATION *tzi)
{
/* Set offset */
if (tzi->StandardDate.wMonth)
{
rule->std_offset = -(tzi->Bias + tzi->StandardBias) * 60;
rule->dlt_offset = -(tzi->Bias + tzi->DaylightBias) * 60;
copy_windows_systemtime (&(tzi->DaylightDate), &(rule->dlt_start));
copy_windows_systemtime (&(tzi->StandardDate), &(rule->dlt_end));
}
else
{
rule->std_offset = -tzi->Bias * 60;
rule->dlt_start.mon = 0;
}
strncpy (rule->std_name, (gchar*)tzi->StandardName, NAME_SIZE - 1);
strncpy (rule->dlt_name, (gchar*)tzi->DaylightName, NAME_SIZE - 1);
}
static gchar*
windows_default_tzname (void)
{
const gchar *subkey =
"SYSTEM\\CurrentControlSet\\Control\\TimeZoneInformation";
HKEY key;
gchar *key_name = NULL;
if (RegOpenKeyExA (HKEY_LOCAL_MACHINE, subkey, 0,
KEY_QUERY_VALUE, &key) == ERROR_SUCCESS)
{
DWORD size = 0;
if (RegQueryValueExA (key, "TimeZoneKeyName", NULL, NULL,
NULL, &size) == ERROR_SUCCESS)
{
key_name = g_malloc ((gint)size);
if (RegQueryValueExA (key, "TimeZoneKeyName", NULL, NULL,
(LPBYTE)key_name, &size) != ERROR_SUCCESS)
{
g_free (key_name);
key_name = NULL;
}
}
RegCloseKey (key);
}
return key_name;
}
typedef struct
{
LONG Bias;
LONG StandardBias;
LONG DaylightBias;
SYSTEMTIME StandardDate;
SYSTEMTIME DaylightDate;
} RegTZI;
static void
system_time_copy (SYSTEMTIME *orig, SYSTEMTIME *target)
{
g_return_if_fail (orig != NULL);
g_return_if_fail (target != NULL);
target->wYear = orig->wYear;
target->wMonth = orig->wMonth;
target->wDayOfWeek = orig->wDayOfWeek;
target->wDay = orig->wDay;
target->wHour = orig->wHour;
target->wMinute = orig->wMinute;
target->wSecond = orig->wSecond;
target->wMilliseconds = orig->wMilliseconds;
}
static void
register_tzi_to_tzi (RegTZI *reg, TIME_ZONE_INFORMATION *tzi)
{
g_return_if_fail (reg != NULL);
g_return_if_fail (tzi != NULL);
tzi->Bias = reg->Bias;
system_time_copy (&(reg->StandardDate), &(tzi->StandardDate));
tzi->StandardBias = reg->StandardBias;
system_time_copy (&(reg->DaylightDate), &(tzi->DaylightDate));
tzi->DaylightBias = reg->DaylightBias;
}
static gint
rules_from_windows_time_zone (const gchar *identifier,
gchar **out_identifier,
TimeZoneRule **rules)
{
HKEY key;
gchar *subkey, *subkey_dynamic;
gchar *key_name = NULL;
const gchar *reg_key =
"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones\\";
TIME_ZONE_INFORMATION tzi;
DWORD size;
gint rules_num = 0;
RegTZI regtzi, regtzi_prev;
g_assert (out_identifier != NULL);
g_assert (rules != NULL);
*out_identifier = NULL;
*rules = NULL;
key_name = NULL;
if (!identifier)
key_name = windows_default_tzname ();
else
key_name = g_strdup (identifier);
if (!key_name)
return 0;
subkey = g_strconcat (reg_key, key_name, NULL);
subkey_dynamic = g_strconcat (subkey, "\\Dynamic DST", NULL);
if (RegOpenKeyExA (HKEY_LOCAL_MACHINE, subkey, 0,
KEY_QUERY_VALUE, &key) != ERROR_SUCCESS)
return 0;
size = sizeof tzi.StandardName;
if (RegQueryValueExA (key, "Std", NULL, NULL,
(LPBYTE)&(tzi.StandardName), &size) != ERROR_SUCCESS)
goto failed;
size = sizeof tzi.DaylightName;
if (RegQueryValueExA (key, "Dlt", NULL, NULL,
(LPBYTE)&(tzi.DaylightName), &size) != ERROR_SUCCESS)
goto failed;
RegCloseKey (key);
if (RegOpenKeyExA (HKEY_LOCAL_MACHINE, subkey_dynamic, 0,
KEY_QUERY_VALUE, &key) == ERROR_SUCCESS)
{
DWORD first, last;
int year, i;
gchar *s;
size = sizeof first;
if (RegQueryValueExA (key, "FirstEntry", NULL, NULL,
(LPBYTE) &first, &size) != ERROR_SUCCESS)
goto failed;
size = sizeof last;
if (RegQueryValueExA (key, "LastEntry", NULL, NULL,
(LPBYTE) &last, &size) != ERROR_SUCCESS)
goto failed;
rules_num = last - first + 2;
*rules = g_new0 (TimeZoneRule, rules_num);
for (year = first, i = 0; year <= last; year++)
{
s = g_strdup_printf ("%d", year);
size = sizeof regtzi;
if (RegQueryValueExA (key, s, NULL, NULL,
(LPBYTE) &regtzi, &size) != ERROR_SUCCESS)
{
g_free (*rules);
*rules = NULL;
break;
}
g_free (s);
if (year > first && memcmp (&regtzi_prev, &regtzi, sizeof regtzi) == 0)
continue;
else
memcpy (&regtzi_prev, &regtzi, sizeof regtzi);
register_tzi_to_tzi (&regtzi, &tzi);
rule_from_windows_time_zone_info (&(*rules)[i], &tzi);
(*rules)[i++].start_year = year;
}
rules_num = i + 1;
failed:
RegCloseKey (key);
}
else if (RegOpenKeyExA (HKEY_LOCAL_MACHINE, subkey, 0,
KEY_QUERY_VALUE, &key) == ERROR_SUCCESS)
{
size = sizeof regtzi;
if (RegQueryValueExA (key, "TZI", NULL, NULL,
(LPBYTE) &regtzi, &size) == ERROR_SUCCESS)
{
rules_num = 2;
*rules = g_new0 (TimeZoneRule, 2);
register_tzi_to_tzi (&regtzi, &tzi);
rule_from_windows_time_zone_info (&(*rules)[0], &tzi);
}
RegCloseKey (key);
}
g_free (subkey_dynamic);
g_free (subkey);
if (*rules)
{
(*rules)[0].start_year = MIN_TZYEAR;
if ((*rules)[rules_num - 2].start_year < MAX_TZYEAR)
(*rules)[rules_num - 1].start_year = MAX_TZYEAR;
else
(*rules)[rules_num - 1].start_year = (*rules)[rules_num - 2].start_year + 1;
*out_identifier = g_steal_pointer (&key_name);
return rules_num;
}
g_free (key_name);
return 0;
}
#endif
static void
find_relative_date (TimeZoneDate *buffer)
{
gint wday;
GDate date;
g_date_clear (&date, 1);
wday = buffer->wday;
/* Get last day if last is needed, first day otherwise */
if (buffer->mon == 13 || buffer->mon == 14) /* Julian Date */
{
g_date_set_dmy (&date, 1, 1, buffer->year);
if (wday >= 59 && buffer->mon == 13 && g_date_is_leap_year (buffer->year))
g_date_add_days (&date, wday);
else
g_date_add_days (&date, wday - 1);
buffer->mon = (int) g_date_get_month (&date);
buffer->mday = (int) g_date_get_day (&date);
buffer->wday = 0;
}
else /* M.W.D */
{
guint days;
guint days_in_month = g_date_days_in_month (buffer->mon, buffer->year);
GDateWeekday first_wday;
g_date_set_dmy (&date, 1, buffer->mon, buffer->year);
first_wday = g_date_get_weekday (&date);
if (first_wday > wday)
++(buffer->week);
/* week is 1 <= w <= 5, we need 0-based */
days = 7 * (buffer->week - 1) + wday - first_wday;
while (days > days_in_month)
days -= 7;
g_date_add_days (&date, days);
buffer->mday = g_date_get_day (&date);
}
}
/* Offset is previous offset of local time. Returns 0 if month is 0 */
static gint64
boundary_for_year (TimeZoneDate *boundary,
gint year,
gint32 offset)
{
TimeZoneDate buffer;
GDate date;
const guint64 unix_epoch_start = 719163L;
const guint64 seconds_per_day = 86400L;
if (!boundary->mon)
return 0;
buffer = *boundary;
if (boundary->year == 0)
{
buffer.year = year;
if (buffer.wday)
find_relative_date (&buffer);
}
g_assert (buffer.year == year);
g_date_clear (&date, 1);
g_date_set_dmy (&date, buffer.mday, buffer.mon, buffer.year);
return ((g_date_get_julian (&date) - unix_epoch_start) * seconds_per_day +
buffer.hour * 3600 + buffer.min * 60 + buffer.sec - offset);
}
static void
fill_transition_info_from_rule (TransitionInfo *info,
TimeZoneRule *rule,
gboolean is_dst)
{
gint offset = is_dst ? rule->dlt_offset : rule->std_offset;
gchar *name = is_dst ? rule->dlt_name : rule->std_name;
info->gmt_offset = offset;
info->is_dst = is_dst;
if (name)
info->abbrev = g_strdup (name);
else
info->abbrev = g_strdup_printf ("%+03d%02d",
(int) offset / 3600,
(int) abs (offset / 60) % 60);
}
static void
init_zone_from_rules (GTimeZone *gtz,
TimeZoneRule *rules,
gint rules_num,
gchar *identifier /* (transfer full) */)
{
guint type_count = 0, trans_count = 0, info_index = 0;
guint ri; /* rule index */
gboolean skip_first_std_trans = TRUE;
gint32 last_offset;
type_count = 0;
trans_count = 0;
/* Last rule only contains max year */
for (ri = 0; ri < rules_num - 1; ri++)
{
if (rules[ri].dlt_start.mon || rules[ri].dlt_end.mon)
{
guint rulespan = (rules[ri + 1].start_year - rules[ri].start_year);
guint transitions = rules[ri].dlt_start.mon > 0 ? 1 : 0;
transitions += rules[ri].dlt_end.mon > 0 ? 1 : 0;
type_count += rules[ri].dlt_start.mon > 0 ? 2 : 1;
trans_count += transitions * rulespan;
}
else
type_count++;
}
gtz->name = g_steal_pointer (&identifier);
gtz->t_info = g_array_sized_new (FALSE, TRUE, sizeof (TransitionInfo), type_count);
gtz->transitions = g_array_sized_new (FALSE, TRUE, sizeof (Transition), trans_count);
last_offset = rules[0].std_offset;
for (ri = 0; ri < rules_num - 1; ri++)
{
if ((rules[ri].std_offset || rules[ri].dlt_offset) &&
rules[ri].dlt_start.mon == 0 && rules[ri].dlt_end.mon == 0)
{
TransitionInfo std_info;
/* Standard */
fill_transition_info_from_rule (&std_info, &(rules[ri]), FALSE);
g_array_append_val (gtz->t_info, std_info);
if (ri > 0 &&
((rules[ri - 1].dlt_start.mon > 12 &&
rules[ri - 1].dlt_start.wday > rules[ri - 1].dlt_end.wday) ||
rules[ri - 1].dlt_start.mon > rules[ri - 1].dlt_end.mon))
{
/* The previous rule was a southern hemisphere rule that
starts the year with DST, so we need to add a
transition to return to standard time */
guint year = rules[ri].start_year;
gint64 std_time = boundary_for_year (&rules[ri].dlt_end,
year, last_offset);
Transition std_trans = {std_time, info_index};
g_array_append_val (gtz->transitions, std_trans);
}
last_offset = rules[ri].std_offset;
++info_index;
skip_first_std_trans = TRUE;
}
else
{
const guint start_year = rules[ri].start_year;
const guint end_year = rules[ri + 1].start_year;
gboolean dlt_first;
guint year;
TransitionInfo std_info, dlt_info;
if (rules[ri].dlt_start.mon > 12)
dlt_first = rules[ri].dlt_start.wday > rules[ri].dlt_end.wday;
else
dlt_first = rules[ri].dlt_start.mon > rules[ri].dlt_end.mon;
/* Standard rules are always even, because before the first
transition is always standard time, and 0 is even. */
fill_transition_info_from_rule (&std_info, &(rules[ri]), FALSE);
fill_transition_info_from_rule (&dlt_info, &(rules[ri]), TRUE);
g_array_append_val (gtz->t_info, std_info);
g_array_append_val (gtz->t_info, dlt_info);
/* Transition dates. We hope that a year which ends daylight
time in a southern-hemisphere country (i.e., one that
begins the year in daylight time) will include a rule
which has only a dlt_end. */
for (year = start_year; year < end_year; year++)
{
gint32 dlt_offset = (dlt_first ? last_offset :
rules[ri].dlt_offset);
gint32 std_offset = (dlt_first ? rules[ri].std_offset :
last_offset);
/* NB: boundary_for_year returns 0 if mon == 0 */
gint64 std_time = boundary_for_year (&rules[ri].dlt_end,
year, dlt_offset);
gint64 dlt_time = boundary_for_year (&rules[ri].dlt_start,
year, std_offset);
Transition std_trans = {std_time, info_index};
Transition dlt_trans = {dlt_time, info_index + 1};
last_offset = (dlt_first ? rules[ri].dlt_offset :
rules[ri].std_offset);
if (dlt_first)
{
if (skip_first_std_trans)
skip_first_std_trans = FALSE;
else if (std_time)
g_array_append_val (gtz->transitions, std_trans);
if (dlt_time)
g_array_append_val (gtz->transitions, dlt_trans);
}
else
{
if (dlt_time)
g_array_append_val (gtz->transitions, dlt_trans);
if (std_time)
g_array_append_val (gtz->transitions, std_trans);
}
}
info_index += 2;
}
}
if (ri > 0 &&
((rules[ri - 1].dlt_start.mon > 12 &&
rules[ri - 1].dlt_start.wday > rules[ri - 1].dlt_end.wday) ||
rules[ri - 1].dlt_start.mon > rules[ri - 1].dlt_end.mon))
{
/* The previous rule was a southern hemisphere rule that
starts the year with DST, so we need to add a
transition to return to standard time */
TransitionInfo info;
guint year = rules[ri].start_year;
Transition trans;
fill_transition_info_from_rule (&info, &(rules[ri - 1]), FALSE);
g_array_append_val (gtz->t_info, info);
trans.time = boundary_for_year (&rules[ri - 1].dlt_end,
year, last_offset);
trans.info_index = info_index;
g_array_append_val (gtz->transitions, trans);
}
}
/*
* parses date[/time] for parsing TZ environment variable
*
* date is either Mm.w.d, Jn or N
* - m is 1 to 12
* - w is 1 to 5
* - d is 0 to 6
* - n is 1 to 365
* - N is 0 to 365
*
* time is either h or hh[[:]mm[[[:]ss]]]
* - h[h] is 0 to 23
* - mm is 00 to 59
* - ss is 00 to 59
*/
static gboolean
parse_mwd_boundary (gchar **pos, TimeZoneDate *boundary)
{
gint month, week, day;
if (**pos == '\0' || **pos < '0' || '9' < **pos)
return FALSE;
month = *(*pos)++ - '0';
if ((month == 1 && **pos >= '0' && '2' >= **pos) ||
(month == 0 && **pos >= '0' && '9' >= **pos))
{
month *= 10;
month += *(*pos)++ - '0';
}
if (*(*pos)++ != '.' || month == 0)
return FALSE;
if (**pos == '\0' || **pos < '1' || '5' < **pos)
return FALSE;
week = *(*pos)++ - '0';
if (*(*pos)++ != '.')
return FALSE;
if (**pos == '\0' || **pos < '0' || '6' < **pos)
return FALSE;
day = *(*pos)++ - '0';
if (!day)
day += 7;
boundary->year = 0;
boundary->mon = month;
boundary->week = week;
boundary->wday = day;
return TRUE;
}
/* Different implementations of tzset interpret the Julian day field
differently. For example, Linux specifies that it should be 1-based
(1 Jan is JD 1) for both Jn and n formats, while zOS and BSD
specify that a Jn JD is 1-based while an n JD is 0-based. Rather
than trying to follow different specs, we will follow GDate's
practice thatIn order to keep it simple, we will follow Linux's
practice. */
static gboolean
parse_julian_boundary (gchar** pos, TimeZoneDate *boundary,
gboolean ignore_leap)
{
gint day = 0;
GDate date;
while (**pos >= '0' && '9' >= **pos)
{
day *= 10;
day += *(*pos)++ - '0';
}
if (day < 1 || 365 < day)
return FALSE;
g_date_clear (&date, 1);
g_date_set_julian (&date, day);
boundary->year = 0;
boundary->mon = (int) g_date_get_month (&date);
boundary->mday = (int) g_date_get_day (&date);
boundary->wday = 0;
if (!ignore_leap && day >= 59)
boundary->mday++;
return TRUE;
}
static gboolean
parse_tz_boundary (const gchar *identifier,
TimeZoneDate *boundary)
{
gchar *pos;
pos = (gchar*)identifier;
/* Month-week-weekday */
if (*pos == 'M')
{
++pos;
if (!parse_mwd_boundary (&pos, boundary))
return FALSE;
}
/* Julian date which ignores Feb 29 in leap years */
else if (*pos == 'J')
{
++pos;
if (!parse_julian_boundary (&pos, boundary, FALSE))
return FALSE ;
}
/* Julian date which counts Feb 29 in leap years */
else if (*pos >= '0' && '9' >= *pos)
{
if (!parse_julian_boundary (&pos, boundary, TRUE))
return FALSE;
}
else
return FALSE;
/* Time */
if (*pos == '/')
{
gint32 offset;
if (!parse_time (++pos, &offset))
return FALSE;
boundary->hour = offset / 3600;
boundary->min = (offset / 60) % 60;
boundary->sec = offset % 3600;
return TRUE;
}
else
{
boundary->hour = 2;
boundary->min = 0;
boundary->sec = 0;
return *pos == '\0';
}
}
static gint
create_ruleset_from_rule (TimeZoneRule **rules, TimeZoneRule *rule)
{
*rules = g_new0 (TimeZoneRule, 2);
(*rules)[0].start_year = MIN_TZYEAR;
(*rules)[1].start_year = MAX_TZYEAR;
(*rules)[0].std_offset = -rule->std_offset;
(*rules)[0].dlt_offset = -rule->dlt_offset;
(*rules)[0].dlt_start = rule->dlt_start;
(*rules)[0].dlt_end = rule->dlt_end;
strcpy ((*rules)[0].std_name, rule->std_name);
strcpy ((*rules)[0].dlt_name, rule->dlt_name);
return 2;
}
static gboolean
parse_offset (gchar **pos, gint32 *target)
{
gchar *buffer;
gchar *target_pos = *pos;
gboolean ret;
while (**pos == '+' || **pos == '-' || **pos == ':' ||
(**pos >= '0' && '9' >= **pos))
++(*pos);
buffer = g_strndup (target_pos, *pos - target_pos);
ret = parse_constant_offset (buffer, target);
g_free (buffer);
return ret;
}
static gboolean
parse_identifier_boundary (gchar **pos, TimeZoneDate *target)
{
gchar *buffer;
gchar *target_pos = *pos;
gboolean ret;
while (**pos != ',' && **pos != '\0')
++(*pos);
buffer = g_strndup (target_pos, *pos - target_pos);
ret = parse_tz_boundary (buffer, target);
g_free (buffer);
return ret;
}
static gboolean
set_tz_name (gchar **pos, gchar *buffer, guint size)
{
gchar *name_pos = *pos;
guint len;
/* Name is ASCII alpha (Is this necessarily true?) */
while (g_ascii_isalpha (**pos))
++(*pos);
/* Name should be three or more alphabetic characters */
if (*pos - name_pos < 3)
return FALSE;
memset (buffer, 0, NAME_SIZE);
/* name_pos isn't 0-terminated, so we have to limit the length expressly */
len = *pos - name_pos > size - 1 ? size - 1 : *pos - name_pos;
strncpy (buffer, name_pos, len);
return TRUE;
}
static gboolean
parse_identifier_boundaries (gchar **pos, TimeZoneRule *tzr)
{
if (*(*pos)++ != ',')
return FALSE;
/* Start date */
if (!parse_identifier_boundary (pos, &(tzr->dlt_start)) || *(*pos)++ != ',')
return FALSE;
/* End date */
if (!parse_identifier_boundary (pos, &(tzr->dlt_end)))
return FALSE;
return TRUE;
}
/*
* Creates an array of TimeZoneRule from a TZ environment variable
* type of identifier. Should free rules afterwards
*/
static gint
rules_from_identifier (const gchar *identifier,
gchar **out_identifier,
TimeZoneRule **rules)
{
gchar *pos;
TimeZoneRule tzr;
g_assert (out_identifier != NULL);
g_assert (rules != NULL);
*out_identifier = NULL;
*rules = NULL;
if (!identifier)
return 0;
pos = (gchar*)identifier;
memset (&tzr, 0, sizeof (tzr));
/* Standard offset */
if (!(set_tz_name (&pos, tzr.std_name, NAME_SIZE)) ||
!parse_offset (&pos, &(tzr.std_offset)))
return 0;
if (*pos == 0)
{
*out_identifier = g_strdup (identifier);
return create_ruleset_from_rule (rules, &tzr);
}
/* Format 2 */
if (!(set_tz_name (&pos, tzr.dlt_name, NAME_SIZE)))
return 0;
parse_offset (&pos, &(tzr.dlt_offset));
if (tzr.dlt_offset == 0) /* No daylight offset given, assume it's 1
hour earlier that standard */
tzr.dlt_offset = tzr.std_offset - 3600;
if (*pos == '\0')
#ifdef G_OS_WIN32
/* Windows allows us to use the US DST boundaries if they're not given */
{
int i;
guint rules_num = 0;
/* Use US rules, Windows' default is Pacific Standard Time */
if ((rules_num = rules_from_windows_time_zone ("Pacific Standard Time",
out_identifier,
rules)))
{
for (i = 0; i < rules_num - 1; i++)
{
(*rules)[i].std_offset = - tzr.std_offset;
(*rules)[i].dlt_offset = - tzr.dlt_offset;
strcpy ((*rules)[i].std_name, tzr.std_name);
strcpy ((*rules)[i].dlt_name, tzr.dlt_name);
}
return rules_num;
}
else
return 0;
}
#else
return 0;
#endif
/* Start and end required (format 2) */
if (!parse_identifier_boundaries (&pos, &tzr))
return 0;
*out_identifier = g_strdup (identifier);
return create_ruleset_from_rule (rules, &tzr);
}
/* Construction {{{1 */
/**
* g_time_zone_new:
* @identifier: (nullable): 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 `TZ` environment
* variable (including %NULL).
*
* In Windows, @identifier can also be the unlocalized name of a time
* zone for standard time, for example "Pacific Standard Time".
*
* Valid RFC3339 time offsets are `"Z"` (for UTC) or
* `"±hh:mm"`. ISO 8601 additionally specifies
* `"±hhmm"` and `"±hh"`. Offsets are
* time values to be added to Coordinated Universal Time (UTC) to get
* the local time.
*
* In UNIX, the `TZ` environment variable typically corresponds
* to the name of a file in the zoneinfo database, or string in
* "std offset [dst [offset],start[/time],end[/time]]" (POSIX) format.
* There are no spaces in the specification. The name of standard
* and daylight savings time zone must be three or more alphabetic
* characters. Offsets are time values to be added to local time to
* get Coordinated Universal Time (UTC) and should be
* `"[±]hh[[:]mm[:ss]]"`. Dates are either
* `"Jn"` (Julian day with n between 1 and 365, leap
* years not counted), `"n"` (zero-based Julian day
* with n between 0 and 365) or `"Mm.w.d"` (day d
* (0 <= d <= 6) of week w (1 <= w <= 5) of month m (1 <= m <= 12), day
* 0 is a Sunday). Times are in local wall clock time, the default is
* 02:00:00.
*
* In Windows, the "tzn[+|–]hh[:mm[:ss]][dzn]" format is used, but also
* accepts POSIX format. The Windows format uses US rules for all time
* zones; daylight savings time is 60 minutes behind the standard time
* with date and time of change taken from Pacific Standard Time.
* Offsets are time values to be added to the local time to get
* Coordinated Universal Time (UTC).
*
* g_time_zone_new_local() calls this function with the value of the
* `TZ` environment variable. This function itself is independent of
* the value of `TZ`, but if @identifier is %NULL then `/etc/localtime`
* will be consulted to discover the correct time zone on UNIX and the
* registry will be consulted or GetTimeZoneInformation() will be used
* to get the local time zone on Windows.
*
* If intervals are not available, only time zone rules from `TZ`
* environment variable or other means, then they will be computed
* from year 1900 to 2037. If the maximum year for the rules is
* available and it is greater than 2037, then it will followed
* instead.
*
* See
* [RFC3339 §5.6](http://tools.ietf.org/html/rfc3339#section-5.6)
* for a precise definition of valid RFC3339 time offsets
* (the `time-offset` expansion) and ISO 8601 for the
* full list of valid time offsets. See
* [The GNU C Library manual](http://www.gnu.org/s/libc/manual/html_node/TZ-Variable.html)
* for an explanation of the possible
* values of the `TZ` environment variable. See
* [Microsoft Time Zone Index Values](http://msdn.microsoft.com/en-us/library/ms912391%28v=winembedded.11%29.aspx)
* for the list of time zones on Windows.
*
* 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 = NULL;
TimeZoneRule *rules;
gint rules_num;
gchar *resolved_identifier = NULL;
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);
if (tz)
{
g_atomic_int_inc (&tz->ref_count);
G_UNLOCK (time_zones);
return tz;
}
}
tz = g_slice_new0 (GTimeZone);
tz->ref_count = 0;
zone_for_constant_offset (tz, identifier);
if (tz->t_info == NULL &&
(rules_num = rules_from_identifier (identifier, &resolved_identifier, &rules)))
{
init_zone_from_rules (tz, rules, rules_num, g_steal_pointer (&resolved_identifier));
g_free (rules);
}
if (tz->t_info == NULL)
{
#ifdef G_OS_UNIX
GBytes *zoneinfo = zone_info_unix (identifier, &resolved_identifier);
if (zoneinfo != NULL)
{
init_zone_from_iana_info (tz, zoneinfo, g_steal_pointer (&resolved_identifier));
g_bytes_unref (zoneinfo);
}
#elif defined (G_OS_WIN32)
if ((rules_num = rules_from_windows_time_zone (identifier,
&resolved_identifier,
&rules)))
{
init_zone_from_rules (tz, rules, rules_num, g_steal_pointer (&resolved_identifier));
g_free (rules);
}
#endif
}
#if defined (G_OS_WIN32)
if (tz->t_info == NULL)
{
if (identifier == NULL)
{
TIME_ZONE_INFORMATION tzi;
if (GetTimeZoneInformation (&tzi) != TIME_ZONE_ID_INVALID)
{
rules = g_new0 (TimeZoneRule, 2);
rule_from_windows_time_zone_info (&rules[0], &tzi);
memset (rules[0].std_name, 0, NAME_SIZE);
memset (rules[0].dlt_name, 0, NAME_SIZE);
rules[0].start_year = MIN_TZYEAR;
rules[1].start_year = MAX_TZYEAR;
init_zone_from_rules (tz, rules, 2, windows_default_tzname ());
g_free (rules);
}
}
}
#endif
g_free (resolved_identifier);
/* Always fall back to UTC. */
if (tz->t_info == NULL)
zone_for_constant_offset (tz, "UTC");
g_assert (tz->name != NULL);
g_assert (tz->t_info != NULL);
if (tz->t_info != NULL)
{
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 `TZ` 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"));
}
/**
* g_time_zone_new_offset:
* @seconds: offset to UTC, in seconds
*
* Creates a #GTimeZone corresponding to the given constant offset from UTC,
* in seconds.
*
* This is equivalent to calling g_time_zone_new() with a string in the form
* `[+|-]hh[:mm[:ss]]`.
*
* Returns: (transfer full): a timezone at the given offset from UTC
* Since: 2.58
*/
GTimeZone *
g_time_zone_new_offset (gint32 seconds)
{
GTimeZone *tz = NULL;
gchar *identifier = NULL;
/* Seemingly, we should be using @seconds directly to set the
* #TransitionInfo.gmt_offset to avoid all this string building and parsing.
* However, we always need to set the #GTimeZone.name to a constructed
* string anyway, so we might as well reuse its code. */
identifier = g_strdup_printf ("%c%02u:%02u:%02u",
(seconds >= 0) ? '+' : '-',
(ABS (seconds) / 60) / 60,
(ABS (seconds) / 60) % 60,
ABS (seconds) % 60);
tz = g_time_zone_new (identifier);
g_free (identifier);
g_assert (g_time_zone_get_offset (tz, 0) == seconds);
return tz;
}
#define TRANSITION(n) g_array_index (tz->transitions, Transition, n)
#define TRANSITION_INFO(n) g_array_index (tz->t_info, TransitionInfo, n)
/* Internal helpers {{{1 */
/* NB: Interval 0 is before the first transition, so there's no
* transition structure to point to which TransitionInfo to
* use. Rule-based zones are set up so that TI 0 is always standard
* time (which is what's in effect before Daylight time got started
* in the early 20th century), but IANA tzfiles don't follow that
* convention. The tzfile documentation says to use the first
* standard-time (i.e., non-DST) tinfo, so that's what we do.
*/
inline static const TransitionInfo*
interval_info (GTimeZone *tz,
guint interval)
{
guint index;
g_return_val_if_fail (tz->t_info != NULL, NULL);
if (interval && tz->transitions && interval <= tz->transitions->len)
index = (TRANSITION(interval - 1)).info_index;
else
{
for (index = 0; index < tz->t_info->len; index++)
{
TransitionInfo *tzinfo = &(TRANSITION_INFO(index));
if (!tzinfo->is_dst)
return tzinfo;
}
index = 0;
}
return &(TRANSITION_INFO(index));
}
inline static gint64
interval_start (GTimeZone *tz,
guint interval)
{
if (!interval || tz->transitions == NULL || tz->transitions->len == 0)
return G_MININT64;
if (interval > tz->transitions->len)
interval = tz->transitions->len;
return (TRANSITION(interval - 1)).time;
}
inline static gint64
interval_end (GTimeZone *tz,
guint interval)
{
if (tz->transitions && interval < tz->transitions->len)
{
gint64 lim = (TRANSITION(interval)).time;
return lim - (lim != G_MININT64);
}
return G_MAXINT64;
}
inline static gint32
interval_offset (GTimeZone *tz,
guint interval)
{
g_return_val_if_fail (tz->t_info != NULL, 0);
return interval_info (tz, interval)->gmt_offset;
}
inline static gboolean
interval_isdst (GTimeZone *tz,
guint interval)
{
g_return_val_if_fail (tz->t_info != NULL, 0);
return interval_info (tz, interval)->is_dst;
}
inline static gchar*
interval_abbrev (GTimeZone *tz,
guint interval)
{
g_return_val_if_fail (tz->t_info != NULL, 0);
return interval_info (tz, interval)->abbrev;
}
inline static gint64
interval_local_start (GTimeZone *tz,
guint interval)
{
if (interval)
return interval_start (tz, interval) + interval_offset (tz, interval);
return G_MININT64;
}
inline static gint64
interval_local_end (GTimeZone *tz,
guint interval)
{
if (tz->transitions && interval < tz->transitions->len)
return interval_end (tz, interval) + interval_offset (tz, interval);
return G_MAXINT64;
}
static gboolean
interval_valid (GTimeZone *tz,
guint interval)
{
if ( tz->transitions == NULL)
return interval == 0;
return interval <= tz->transitions->len;
}
/* 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;
guint intervals;
if (tz->transitions == NULL)
return 0;
intervals = tz->transitions->len;
/* find the interval containing *time UTC
* TODO: this could be binary searched (or better) */
for (i = 0; i <= intervals; 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 < intervals &&
*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 as 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;
guint intervals;
if (tz->transitions == NULL)
return 0;
intervals = tz->transitions->len;
for (i = 0; i <= intervals; 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 < intervals && 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, (guint)interval), NULL);
return interval_abbrev (tz, (guint)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, (guint)interval), 0);
return interval_offset (tz, (guint)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->transitions == NULL)
return FALSE;
return interval_isdst (tz, (guint)interval);
}
/**
* g_time_zone_get_identifier:
* @tz: a #GTimeZone
*
* Get the identifier of this #GTimeZone, as passed to g_time_zone_new().
* If the identifier passed at construction time was not recognised, `UTC` will
* be returned. If it was %NULL, the identifier of the local timezone at
* construction time will be returned.
*
* The identifier will be returned in the same format as provided at
* construction time: if provided as a time offset, that will be returned by
* this function.
*
* Returns: identifier for this timezone
* Since: 2.58
*/
const gchar *
g_time_zone_get_identifier (GTimeZone *tz)
{
g_return_val_if_fail (tz != NULL, NULL);
return tz->name;
}
/* Epilogue {{{1 */
/* vim:set foldmethod=marker: */
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