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89dba59590
pgtime.h documented the PG interpretation of tm_mon right alongside the POSIX interpretation of tm_year, with no hint that neither comment was correct throughout our code. Perhaps someday we ought to switch to using two separate struct definitions to provide a clearer indication of which semantics are in use where. But I fear the tedium-versus-safety-gain tradeoff would not be very good. Discussion: https://postgr.es/m/CAJ7c6TOMG8zSNEZtCn5SPe+cCk3Lfxb71ZaQwT2F4T7PJ_t=KA@mail.gmail.com
92 lines
2.6 KiB
C
92 lines
2.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* pgtime.h
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* PostgreSQL internal timezone library
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*
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* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/include/pgtime.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef _PGTIME_H
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#define _PGTIME_H
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/*
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* The API of this library is generally similar to the corresponding
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* C library functions, except that we use pg_time_t which (we hope) is
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* 64 bits wide, and which is most definitely signed not unsigned.
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*/
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typedef int64 pg_time_t;
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/*
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* CAUTION: the IANA timezone library (src/timezone/) follows the POSIX
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* convention that tm_mon counts from 0 and tm_year is relative to 1900.
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* However, Postgres' datetime functions generally treat tm_mon as counting
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* from 1 and tm_year as relative to 1 BC. Be sure to make the appropriate
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* adjustments when moving from one code domain to the other.
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*/
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struct pg_tm
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{
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int tm_sec;
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int tm_min;
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int tm_hour;
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int tm_mday;
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int tm_mon; /* see above */
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int tm_year; /* see above */
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int tm_wday;
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int tm_yday;
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int tm_isdst;
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long int tm_gmtoff;
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const char *tm_zone;
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};
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typedef struct pg_tz pg_tz;
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typedef struct pg_tzenum pg_tzenum;
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/* Maximum length of a timezone name (not including trailing null) */
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#define TZ_STRLEN_MAX 255
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/* these functions are in localtime.c */
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extern struct pg_tm *pg_localtime(const pg_time_t *timep, const pg_tz *tz);
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extern struct pg_tm *pg_gmtime(const pg_time_t *timep);
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extern int pg_next_dst_boundary(const pg_time_t *timep,
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long int *before_gmtoff,
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int *before_isdst,
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pg_time_t *boundary,
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long int *after_gmtoff,
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int *after_isdst,
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const pg_tz *tz);
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extern bool pg_interpret_timezone_abbrev(const char *abbrev,
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const pg_time_t *timep,
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long int *gmtoff,
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int *isdst,
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const pg_tz *tz);
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extern bool pg_get_timezone_offset(const pg_tz *tz, long int *gmtoff);
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extern const char *pg_get_timezone_name(pg_tz *tz);
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extern bool pg_tz_acceptable(pg_tz *tz);
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/* these functions are in strftime.c */
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extern size_t pg_strftime(char *s, size_t max, const char *format,
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const struct pg_tm *tm);
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/* these functions and variables are in pgtz.c */
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extern PGDLLIMPORT pg_tz *session_timezone;
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extern pg_tz *log_timezone;
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extern void pg_timezone_initialize(void);
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extern pg_tz *pg_tzset(const char *tzname);
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extern pg_tz *pg_tzset_offset(long gmtoffset);
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extern pg_tzenum *pg_tzenumerate_start(void);
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extern pg_tz *pg_tzenumerate_next(pg_tzenum *dir);
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extern void pg_tzenumerate_end(pg_tzenum *dir);
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#endif /* _PGTIME_H */
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