Simplify and standardize conversions between TEXT datums and ordinary C

strings.  This patch introduces four support functions cstring_to_text,
cstring_to_text_with_len, text_to_cstring, and text_to_cstring_buffer, and
two macros CStringGetTextDatum and TextDatumGetCString.  A number of
existing macros that provided variants on these themes were removed.

Most of the places that need to make such conversions now require just one
function or macro call, in place of the multiple notational layers that used
to be needed.  There are no longer any direct calls of textout or textin,
and we got most of the places that were using handmade conversions via
memcpy (there may be a few still lurking, though).

This commit doesn't make any serious effort to eliminate transient memory
leaks caused by detoasting toasted text objects before they reach
text_to_cstring.  We changed PG_GETARG_TEXT_P to PG_GETARG_TEXT_PP in a few
places where it was easy, but much more could be done.

Brendan Jurd and Tom Lane

1 files changed, 30 insertions, 40 deletions

diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index 8ca6f998c98..8a0f37292dc 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.186 2008/03/21 01:31:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.187 2008/03/25 22:42:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3242,7 +3242,7 @@ timestamptz_age(PG_FUNCTION_ARGS)
 Datum
 timestamp_trunc(PG_FUNCTION_ARGS)
 {
-	text	   *units = PG_GETARG_TEXT_P(0);
+	text	   *units = PG_GETARG_TEXT_PP(0);
 	Timestamp	timestamp = PG_GETARG_TIMESTAMP(1);
 	Timestamp	result;
 	int			type,
@@ -3255,8 +3255,8 @@ timestamp_trunc(PG_FUNCTION_ARGS)
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_TIMESTAMP(timestamp);
 
-	lowunits = downcase_truncate_identifier(VARDATA(units),
-											VARSIZE(units) - VARHDRSZ,
+	lowunits = downcase_truncate_identifier(VARDATA_ANY(units),
+											VARSIZE_ANY_EXHDR(units),
 											false);
 
 	type = DecodeUnits(0, lowunits, &val);
@@ -3374,7 +3374,7 @@ timestamp_trunc(PG_FUNCTION_ARGS)
 Datum
 timestamptz_trunc(PG_FUNCTION_ARGS)
 {
-	text	   *units = PG_GETARG_TEXT_P(0);
+	text	   *units = PG_GETARG_TEXT_PP(0);
 	TimestampTz timestamp = PG_GETARG_TIMESTAMPTZ(1);
 	TimestampTz result;
 	int			tz;
@@ -3390,8 +3390,8 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_TIMESTAMPTZ(timestamp);
 
-	lowunits = downcase_truncate_identifier(VARDATA(units),
-											VARSIZE(units) - VARHDRSZ,
+	lowunits = downcase_truncate_identifier(VARDATA_ANY(units),
+											VARSIZE_ANY_EXHDR(units),
 											false);
 
 	type = DecodeUnits(0, lowunits, &val);
@@ -3532,7 +3532,7 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
 Datum
 interval_trunc(PG_FUNCTION_ARGS)
 {
-	text	   *units = PG_GETARG_TEXT_P(0);
+	text	   *units = PG_GETARG_TEXT_PP(0);
 	Interval   *interval = PG_GETARG_INTERVAL_P(1);
 	Interval   *result;
 	int			type,
@@ -3544,8 +3544,8 @@ interval_trunc(PG_FUNCTION_ARGS)
 
 	result = (Interval *) palloc(sizeof(Interval));
 
-	lowunits = downcase_truncate_identifier(VARDATA(units),
-											VARSIZE(units) - VARHDRSZ,
+	lowunits = downcase_truncate_identifier(VARDATA_ANY(units),
+											VARSIZE_ANY_EXHDR(units),
 											false);
 
 	type = DecodeUnits(0, lowunits, &val);
@@ -3615,9 +3615,7 @@ interval_trunc(PG_FUNCTION_ARGS)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 				 errmsg("interval units \"%s\" not recognized",
-						DatumGetCString(DirectFunctionCall1(textout,
-												 PointerGetDatum(units))))));
-		*result = *interval;
+						lowunits)));
 	}
 
 	PG_RETURN_INTERVAL_P(result);
@@ -3803,7 +3801,7 @@ date2isoyearday(int year, int mon, int mday)
 Datum
 timestamp_part(PG_FUNCTION_ARGS)
 {
-	text	   *units = PG_GETARG_TEXT_P(0);
+	text	   *units = PG_GETARG_TEXT_PP(0);
 	Timestamp	timestamp = PG_GETARG_TIMESTAMP(1);
 	float8		result;
 	int			type,
@@ -3819,8 +3817,8 @@ timestamp_part(PG_FUNCTION_ARGS)
 		PG_RETURN_FLOAT8(result);
 	}
 
-	lowunits = downcase_truncate_identifier(VARDATA(units),
-											VARSIZE(units) - VARHDRSZ,
+	lowunits = downcase_truncate_identifier(VARDATA_ANY(units),
+											VARSIZE_ANY_EXHDR(units),
 											false);
 
 	type = DecodeUnits(0, lowunits, &val);
@@ -4031,7 +4029,7 @@ timestamp_part(PG_FUNCTION_ARGS)
 Datum
 timestamptz_part(PG_FUNCTION_ARGS)
 {
-	text	   *units = PG_GETARG_TEXT_P(0);
+	text	   *units = PG_GETARG_TEXT_PP(0);
 	TimestampTz timestamp = PG_GETARG_TIMESTAMPTZ(1);
 	float8		result;
 	int			tz;
@@ -4050,8 +4048,8 @@ timestamptz_part(PG_FUNCTION_ARGS)
 		PG_RETURN_FLOAT8(result);
 	}
 
-	lowunits = downcase_truncate_identifier(VARDATA(units),
-											VARSIZE(units) - VARHDRSZ,
+	lowunits = downcase_truncate_identifier(VARDATA_ANY(units),
+											VARSIZE_ANY_EXHDR(units),
 											false);
 
 	type = DecodeUnits(0, lowunits, &val);
@@ -4246,7 +4244,7 @@ timestamptz_part(PG_FUNCTION_ARGS)
 Datum
 interval_part(PG_FUNCTION_ARGS)
 {
-	text	   *units = PG_GETARG_TEXT_P(0);
+	text	   *units = PG_GETARG_TEXT_PP(0);
 	Interval   *interval = PG_GETARG_INTERVAL_P(1);
 	float8		result;
 	int			type,
@@ -4256,8 +4254,8 @@ interval_part(PG_FUNCTION_ARGS)
 	struct pg_tm tt,
 			   *tm = &tt;
 
-	lowunits = downcase_truncate_identifier(VARDATA(units),
-											VARSIZE(units) - VARHDRSZ,
+	lowunits = downcase_truncate_identifier(VARDATA_ANY(units),
+											VARSIZE_ANY_EXHDR(units),
 											false);
 
 	type = DecodeUnits(0, lowunits, &val);
@@ -4337,8 +4335,7 @@ interval_part(PG_FUNCTION_ARGS)
 					ereport(ERROR,
 							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 							 errmsg("interval units \"%s\" not supported",
-								 DatumGetCString(DirectFunctionCall1(textout,
-												 PointerGetDatum(units))))));
+									lowunits)));
 					result = 0;
 			}
 
@@ -4365,8 +4362,7 @@ interval_part(PG_FUNCTION_ARGS)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 				 errmsg("interval units \"%s\" not recognized",
-						DatumGetCString(DirectFunctionCall1(textout,
-												 PointerGetDatum(units))))));
+						lowunits)));
 		result = 0;
 	}
 
@@ -4385,13 +4381,12 @@ interval_part(PG_FUNCTION_ARGS)
 Datum
 timestamp_zone(PG_FUNCTION_ARGS)
 {
-	text	   *zone = PG_GETARG_TEXT_P(0);
+	text	   *zone = PG_GETARG_TEXT_PP(0);
 	Timestamp	timestamp = PG_GETARG_TIMESTAMP(1);
 	TimestampTz result;
 	int			tz;
 	pg_tz	   *tzp;
 	char		tzname[TZ_STRLEN_MAX + 1];
-	int			len;
 
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_TIMESTAMPTZ(timestamp);
@@ -4401,9 +4396,7 @@ timestamp_zone(PG_FUNCTION_ARGS)
 	 * (to handle cases like "America/New_York"), and if that fails, we look
 	 * in the date token table (to handle cases like "EST").
 	 */
-	len = Min(VARSIZE(zone) - VARHDRSZ, TZ_STRLEN_MAX);
-	memcpy(tzname, VARDATA(zone), len);
-	tzname[len] = '\0';
+	text_to_cstring_buffer(zone, tzname, sizeof(tzname));
 	tzp = pg_tzset(tzname);
 	if (tzp)
 	{
@@ -4428,8 +4421,8 @@ timestamp_zone(PG_FUNCTION_ARGS)
 		int			type,
 					val;
 
-		lowzone = downcase_truncate_identifier(VARDATA(zone),
-											   VARSIZE(zone) - VARHDRSZ,
+		lowzone = downcase_truncate_identifier(tzname,
+											   strlen(tzname),
 											   false);
 		type = DecodeSpecial(0, lowzone, &val);
 
@@ -4558,13 +4551,12 @@ timestamptz_timestamp(PG_FUNCTION_ARGS)
 Datum
 timestamptz_zone(PG_FUNCTION_ARGS)
 {
-	text	   *zone = PG_GETARG_TEXT_P(0);
+	text	   *zone = PG_GETARG_TEXT_PP(0);
 	TimestampTz timestamp = PG_GETARG_TIMESTAMPTZ(1);
 	Timestamp	result;
 	int			tz;
 	pg_tz	   *tzp;
 	char		tzname[TZ_STRLEN_MAX + 1];
-	int			len;
 
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_TIMESTAMP(timestamp);
@@ -4574,9 +4566,7 @@ timestamptz_zone(PG_FUNCTION_ARGS)
 	 * (to handle cases like "America/New_York"), and if that fails, we look
 	 * in the date token table (to handle cases like "EST").
 	 */
-	len = Min(VARSIZE(zone) - VARHDRSZ, TZ_STRLEN_MAX);
-	memcpy(tzname, VARDATA(zone), len);
-	tzname[len] = '\0';
+	text_to_cstring_buffer(zone, tzname, sizeof(tzname));
 	tzp = pg_tzset(tzname);
 	if (tzp)
 	{
@@ -4600,8 +4590,8 @@ timestamptz_zone(PG_FUNCTION_ARGS)
 		int			type,
 					val;
 
-		lowzone = downcase_truncate_identifier(VARDATA(zone),
-											   VARSIZE(zone) - VARHDRSZ,
+		lowzone = downcase_truncate_identifier(tzname,
+											   strlen(tzname),
 											   false);
 		type = DecodeSpecial(0, lowzone, &val);