database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-19 13:42:17 +03:00
Code Activity

Refactor datetime functions' timezone lookup code to reduce duplication.

Browse Source 
We already had five copies of essentially the same logic, and an
upcoming patch introduces yet another use-case.  That's past my
threshold of pain, so introduce a common subroutine.  There's not
that much net code savings, but the chance of typos should go down.

Inspired by a patch from Przemysław Sztoch, but different in detail.

Discussion: https://postgr.es/m/01a84551-48dd-1359-bf7e-f6b0203a6bd0@sztoch.pl
This commit is contained in:
Tom Lane
2023-03-17 17:47:15 -04:00
parent cc1392d4aa
commit 3e59e5048d
4 changed files with 142 additions and 180 deletions
Download Patch File Download Diff File Expand all files Collapse all files

85
src/backend/utils/adt/datetime.c
View File

@@ -26,6 +26,7 @@
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "parser/scansup.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/datetime.h"
@@ -3162,6 +3163,90 @@ DecodeSpecial(int field, const char *lowtoken, int *val)
}
/* DecodeTimezoneName()
* Interpret string as a timezone abbreviation or name.
* Throw error if the name is not recognized.
*
* The return value indicates what kind of zone identifier it is:
* TZNAME_FIXED_OFFSET: fixed offset from UTC
* TZNAME_DYNTZ: dynamic timezone abbreviation
* TZNAME_ZONE: full tzdb zone name
*
* For TZNAME_FIXED_OFFSET, *offset receives the UTC offset (in seconds,
* with ISO sign convention: positive is east of Greenwich).
* For the other two cases, *tz receives the timezone struct representing
* the zone name or the abbreviation's underlying zone.
*/
int
DecodeTimezoneName(const char *tzname, int *offset, pg_tz **tz)
{
char *lowzone;
int dterr,
type;
DateTimeErrorExtra extra;
/*
* First we look in the timezone abbreviation table (to handle cases like
* "EST"), and if that fails, we look in the timezone database (to handle
* cases like "America/New_York"). This matches the order in which
* timestamp input checks the cases; it's important because the timezone
* database unwisely uses a few zone names that are identical to offset
* abbreviations.
*/
/* DecodeTimezoneAbbrev requires lowercase input */
lowzone = downcase_truncate_identifier(tzname,
strlen(tzname),
false);
dterr = DecodeTimezoneAbbrev(0, lowzone, &type, offset, tz, &extra);
if (dterr)
DateTimeParseError(dterr, &extra, NULL, NULL, NULL);
if (type == TZ || type == DTZ)
{
/* fixed-offset abbreviation, return the offset */
return TZNAME_FIXED_OFFSET;
}
else if (type == DYNTZ)
{
/* dynamic-offset abbreviation, return its referenced timezone */
return TZNAME_DYNTZ;
}
else
{
/* try it as a full zone name */
*tz = pg_tzset(tzname);
if (*tz == NULL)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("time zone \"%s\" not recognized", tzname)));
return TZNAME_ZONE;
}
}
/* DecodeTimezoneNameToTz()
* Interpret string as a timezone abbreviation or name.
* Throw error if the name is not recognized.
*
* This is a simple wrapper for DecodeTimezoneName that produces a pg_tz *
* result in all cases.
*/
pg_tz *
DecodeTimezoneNameToTz(const char *tzname)
{
pg_tz *result;
int offset;
if (DecodeTimezoneName(tzname, &offset, &result) == TZNAME_FIXED_OFFSET)
{
/* fixed-offset abbreviation, get a pg_tz descriptor for that */
result = pg_tzset_offset(-offset); /* flip to POSIX sign convention */
}
return result;
}
/* ClearPgItmIn
*
* Zero out a pg_itm_in