mariadb/sql/tztime.h
Rucha Deodhar 94eb819296 MDEV-31684 Add timezone information to DATE_FORMAT
Before starting to go over the format string, prepare the current time
zone information incase '%z' or '%Z' is encountered.
This information can be obtained as given below:

A) If timezone is not set ( meaning we are working with system timezone):
Get the MYSQL_TIME representation for current time and GMT time using
current thread variable for timezone and timezone variable for UTC
respectively. This MYSQL_TIME variable will be used to calculate time
difference. Also convert current time in second to tm structure to
get system timezone information.

B) If timezone is set as offset:
Get timezone information using current timezone information and store
in appropriate variable.

C) If timezone is set as some place (example: Europe/Berlin)
Get timezone information by searching the timezone. During internal
timezone search, information like timeoffset from UTC and abbrevation
is stored in another relevant structure. Hence use the same information.
2023-10-11 21:49:13 +05:30

108 lines
3.6 KiB
C++

#ifndef TZTIME_INCLUDED
#define TZTIME_INCLUDED
/* Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
#ifdef USE_PRAGMA_INTERFACE
#pragma interface /* gcc class interface */
#endif
#include "my_time.h" /* my_time_t */
#include "mysql_time.h" /* MYSQL_TIME */
#include "sql_list.h" /* Sql_alloc */
#include "sql_string.h" /* String */
class THD;
#if !defined(TESTTIME) && !defined(TZINFO2SQL)
class THD;
/**
This class represents abstract time zone and provides
basic interface for MYSQL_TIME <-> my_time_t conversion.
Actual time zones which are specified by DB, or via offset
or use system functions are its descendants.
*/
/*
Has only offset from UTC, bool value to denote if it is
ahead (+), behind(-) of UTC and abbrevation.
*/
struct tz
{
long seconds_offset;
bool is_behind;
char abbrevation[8];
bool is_inited;
};
class Time_zone: public Sql_alloc
{
public:
Time_zone() = default; /* Remove gcc warning */
/**
Converts local time in broken down MYSQL_TIME representation to
my_time_t (UTC seconds since Epoch) represenation.
Returns 0 in case of error. May set error_code to ER_WARN_DATA_OUT_OF_RANGE
or ER_WARN_INVALID_TIMESTAMP, see TIME_to_timestamp())
*/
virtual my_time_t TIME_to_gmt_sec(const MYSQL_TIME *t,
uint *error_code) const = 0;
/**
Converts time in my_time_t representation to local time in
broken down MYSQL_TIME representation.
*/
virtual void gmt_sec_to_TIME(MYSQL_TIME *tmp, my_time_t t) const = 0;
/**
Because of constness of String returned by get_name() time zone name
have to be already zeroended to be able to use String::ptr() instead
of c_ptr().
*/
virtual const String * get_name() const = 0;
virtual void get_timezone_information(struct tz* curr_tz, const MYSQL_TIME *local_TIME) const = 0;
/**
We need this only for surpressing warnings, objects of this type are
allocated on MEM_ROOT and should not require destruction.
*/
virtual ~Time_zone() = default;
protected:
static inline void adjust_leap_second(MYSQL_TIME *t);
};
extern Time_zone * my_tz_UTC;
extern MYSQL_PLUGIN_IMPORT Time_zone * my_tz_SYSTEM;
extern Time_zone * my_tz_OFFSET0;
extern Time_zone * my_tz_find(THD *thd, const String *name);
extern my_bool my_tz_init(THD *org_thd, const char *default_tzname, my_bool bootstrap);
extern void my_tz_free();
extern my_time_t sec_since_epoch_TIME(MYSQL_TIME *t);
/**
Number of elements in table list produced by my_tz_get_table_list()
(this table list contains tables which are needed for dynamical loading
of time zone descriptions). Actually it is imlementation detail that
should not be used anywhere outside of tztime.h and tztime.cc.
*/
static const int MY_TZ_TABLES_COUNT= 4;
#endif /* !defined(TESTTIME) && !defined(TZINFO2SQL) */
#endif /* TZTIME_INCLUDED */