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Refactor datetime functions' timezone lookup code to reduce duplication.

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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
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51
src/backend/utils/adt/date.c
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@@ -3052,38 +3052,23 @@ timetz_zone(PG_FUNCTION_ARGS)
TimeTzADT *result;
int tz;
char tzname[TZ_STRLEN_MAX + 1];
char *lowzone;
int dterr,
type,
int type,
val;
pg_tz *tzp;
DateTimeErrorExtra extra;
/*
* Look up the requested timezone. 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.)
* Look up the requested timezone.
*/
text_to_cstring_buffer(zone, tzname, sizeof(tzname));
/* DecodeTimezoneAbbrev requires lowercase input */
lowzone = downcase_truncate_identifier(tzname,
strlen(tzname),
false);
type = DecodeTimezoneName(tzname, &val, &tzp);
dterr = DecodeTimezoneAbbrev(0, lowzone, &type, &val, &tzp, &extra);
if (dterr)
DateTimeParseError(dterr, &extra, NULL, NULL, NULL);
if (type == TZ || type == DTZ)
if (type == TZNAME_FIXED_OFFSET)
{
/* fixed-offset abbreviation */
tz = -val;
}
else if (type == DYNTZ)
else if (type == TZNAME_DYNTZ)
{
/* dynamic-offset abbreviation, resolve using transaction start time */
TimestampTz now = GetCurrentTransactionStartTimestamp();
@@ -3093,27 +3078,15 @@ timetz_zone(PG_FUNCTION_ARGS)
}
else
{
/* try it as a full zone name */
tzp = pg_tzset(tzname);
if (tzp)
{
/* Get the offset-from-GMT that is valid now for the zone */
TimestampTz now = GetCurrentTransactionStartTimestamp();
struct pg_tm tm;
fsec_t fsec;
/* Get the offset-from-GMT that is valid now for the zone name */
TimestampTz now = GetCurrentTransactionStartTimestamp();
struct pg_tm tm;
fsec_t fsec;
if (timestamp2tm(now, &tz, &tm, &fsec, NULL, tzp) != 0)
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("timestamp out of range")));
}
else
{
if (timestamp2tm(now, &tz, &tm, &fsec, NULL, tzp) != 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("time zone \"%s\" not recognized", tzname)));
tz = 0; /* keep compiler quiet */
}
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("timestamp out of range")));
}
result = (TimeTzADT *) palloc(sizeof(TimeTzADT));