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, 41 insertions, 37 deletions

diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index f0a668b2927..c4960bcecfb 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.70 2008/03/24 19:12:49 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.71 2008/03/25 22:42:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -141,10 +141,6 @@ static void SPI_sql_row_to_xmlelement(int rownum, StringInfo result,
 			 errhint("You need to rebuild PostgreSQL using --with-libxml.")))
 
 
-#define _textin(str) DirectFunctionCall1(textin, CStringGetDatum(str))
-#define _textout(x) DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(x)))
-
-
 /* from SQL/XML:2003 section 4.7 */
 #define NAMESPACE_XSD "http://www.w3.org/2001/XMLSchema"
 #define NAMESPACE_XSI "http://www.w3.org/2001/XMLSchema-instance"
@@ -168,19 +164,22 @@ xmlChar_to_encoding(xmlChar * encoding_name)
 #endif
 
 
+/*
+ * xml_in uses a plain C string to VARDATA conversion, so for the time being
+ * we use the conversion function for the text datatype.
+ *
+ * This is only acceptable so long as xmltype and text use the same
+ * representation.
+ */
 Datum
 xml_in(PG_FUNCTION_ARGS)
 {
 #ifdef USE_LIBXML
 	char	   *s = PG_GETARG_CSTRING(0);
-	size_t		len;
 	xmltype    *vardata;
 	xmlDocPtr	doc;
 
-	len = strlen(s);
-	vardata = palloc(len + VARHDRSZ);
-	SET_VARSIZE(vardata, len + VARHDRSZ);
-	memcpy(VARDATA(vardata), s, len);
+	vardata = (xmltype *) cstring_to_text(s);
 
 	/*
 	 * Parse the data to check if it is well-formed XML data.  Assume that
@@ -200,6 +199,13 @@ xml_in(PG_FUNCTION_ARGS)
 #define PG_XML_DEFAULT_VERSION "1.0"
 
 
+/*
+ * xml_out_internal uses a plain VARDATA to C string conversion, so for the
+ * time being we use the conversion function for the text datatype.
+ *
+ * This is only acceptable so long as xmltype and text use the same
+ * representation.
+ */
 static char *
 xml_out_internal(xmltype *x, pg_enc target_encoding)
 {
@@ -213,10 +219,8 @@ xml_out_internal(xmltype *x, pg_enc target_encoding)
 	int			res_code;
 #endif
 
-	len = VARSIZE(x) - VARHDRSZ;
-	str = palloc(len + 1);
-	memcpy(str, VARDATA(x), len);
-	str[len] = '\0';
+	str = text_to_cstring((text *) x);
+	len = strlen(str);
 
 #ifdef USE_LIBXML
 	if ((res_code = parse_xml_decl((xmlChar *) str,
@@ -713,7 +717,7 @@ xmlpi(char *target, text *arg, bool arg_is_null, bool *result_is_null)
 	{
 		char	   *string;
 
-		string = _textout(arg);
+		string = text_to_cstring(arg);
 		if (strstr(string, "?>") != NULL)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_XML_PROCESSING_INSTRUCTION),
@@ -1930,7 +1934,7 @@ table_to_xml(PG_FUNCTION_ARGS)
 	Oid			relid = PG_GETARG_OID(0);
 	bool		nulls = PG_GETARG_BOOL(1);
 	bool		tableforest = PG_GETARG_BOOL(2);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(3));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
 
 	PG_RETURN_XML_P(stringinfo_to_xmltype(table_to_xml_internal(relid, NULL,
 														  nulls, tableforest,
@@ -1941,10 +1945,10 @@ table_to_xml(PG_FUNCTION_ARGS)
 Datum
 query_to_xml(PG_FUNCTION_ARGS)
 {
-	char	   *query = _textout(PG_GETARG_TEXT_P(0));
+	char	   *query = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	bool		nulls = PG_GETARG_BOOL(1);
 	bool		tableforest = PG_GETARG_BOOL(2);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(3));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
 
 	PG_RETURN_XML_P(stringinfo_to_xmltype(query_to_xml_internal(query, NULL,
 													NULL, nulls, tableforest,
@@ -1955,11 +1959,11 @@ query_to_xml(PG_FUNCTION_ARGS)
 Datum
 cursor_to_xml(PG_FUNCTION_ARGS)
 {
-	char	   *name = _textout(PG_GETARG_TEXT_P(0));
+	char	   *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	int32		count = PG_GETARG_INT32(1);
 	bool		nulls = PG_GETARG_BOOL(2);
 	bool		tableforest = PG_GETARG_BOOL(3);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(4));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(4));
 
 	StringInfoData result;
 	Portal		portal;
@@ -2079,7 +2083,7 @@ table_to_xmlschema(PG_FUNCTION_ARGS)
 	Oid			relid = PG_GETARG_OID(0);
 	bool		nulls = PG_GETARG_BOOL(1);
 	bool		tableforest = PG_GETARG_BOOL(2);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(3));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
 	const char *result;
 	Relation	rel;
 
@@ -2095,10 +2099,10 @@ table_to_xmlschema(PG_FUNCTION_ARGS)
 Datum
 query_to_xmlschema(PG_FUNCTION_ARGS)
 {
-	char	   *query = _textout(PG_GETARG_TEXT_P(0));
+	char	   *query = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	bool		nulls = PG_GETARG_BOOL(1);
 	bool		tableforest = PG_GETARG_BOOL(2);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(3));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
 	const char *result;
 	SPIPlanPtr	plan;
 	Portal		portal;
@@ -2124,10 +2128,10 @@ query_to_xmlschema(PG_FUNCTION_ARGS)
 Datum
 cursor_to_xmlschema(PG_FUNCTION_ARGS)
 {
-	char	   *name = _textout(PG_GETARG_TEXT_P(0));
+	char	   *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	bool		nulls = PG_GETARG_BOOL(1);
 	bool		tableforest = PG_GETARG_BOOL(2);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(3));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
 	const char *xmlschema;
 	Portal		portal;
 
@@ -2153,7 +2157,7 @@ table_to_xml_and_xmlschema(PG_FUNCTION_ARGS)
 	Oid			relid = PG_GETARG_OID(0);
 	bool		nulls = PG_GETARG_BOOL(1);
 	bool		tableforest = PG_GETARG_BOOL(2);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(3));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
 	Relation	rel;
 	const char *xmlschema;
 
@@ -2171,10 +2175,10 @@ table_to_xml_and_xmlschema(PG_FUNCTION_ARGS)
 Datum
 query_to_xml_and_xmlschema(PG_FUNCTION_ARGS)
 {
-	char	   *query = _textout(PG_GETARG_TEXT_P(0));
+	char	   *query = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	bool		nulls = PG_GETARG_BOOL(1);
 	bool		tableforest = PG_GETARG_BOOL(2);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(3));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
 
 	const char *xmlschema;
 	SPIPlanPtr	plan;
@@ -2255,7 +2259,7 @@ schema_to_xml(PG_FUNCTION_ARGS)
 	Name		name = PG_GETARG_NAME(0);
 	bool		nulls = PG_GETARG_BOOL(1);
 	bool		tableforest = PG_GETARG_BOOL(2);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(3));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
 
 	char	   *schemaname;
 	Oid			nspid;
@@ -2346,7 +2350,7 @@ schema_to_xmlschema(PG_FUNCTION_ARGS)
 	Name		name = PG_GETARG_NAME(0);
 	bool		nulls = PG_GETARG_BOOL(1);
 	bool		tableforest = PG_GETARG_BOOL(2);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(3));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
 
 	PG_RETURN_XML_P(stringinfo_to_xmltype(schema_to_xmlschema_internal(NameStr(*name),
 											 nulls, tableforest, targetns)));
@@ -2359,7 +2363,7 @@ schema_to_xml_and_xmlschema(PG_FUNCTION_ARGS)
 	Name		name = PG_GETARG_NAME(0);
 	bool		nulls = PG_GETARG_BOOL(1);
 	bool		tableforest = PG_GETARG_BOOL(2);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(3));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
 	char	   *schemaname;
 	Oid			nspid;
 	StringInfo	xmlschema;
@@ -2431,7 +2435,7 @@ database_to_xml(PG_FUNCTION_ARGS)
 {
 	bool		nulls = PG_GETARG_BOOL(0);
 	bool		tableforest = PG_GETARG_BOOL(1);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(2));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(2));
 
 	PG_RETURN_XML_P(stringinfo_to_xmltype(database_to_xml_internal(NULL, nulls,
 													tableforest, targetns)));
@@ -2486,7 +2490,7 @@ database_to_xmlschema(PG_FUNCTION_ARGS)
 {
 	bool		nulls = PG_GETARG_BOOL(0);
 	bool		tableforest = PG_GETARG_BOOL(1);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(2));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(2));
 
 	PG_RETURN_XML_P(stringinfo_to_xmltype(database_to_xmlschema_internal(nulls,
 													tableforest, targetns)));
@@ -2498,7 +2502,7 @@ database_to_xml_and_xmlschema(PG_FUNCTION_ARGS)
 {
 	bool		nulls = PG_GETARG_BOOL(0);
 	bool		tableforest = PG_GETARG_BOOL(1);
-	const char *targetns = _textout(PG_GETARG_TEXT_P(2));
+	const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(2));
 	StringInfo	xmlschema;
 
 	xmlschema = database_to_xmlschema_internal(nulls, tableforest, targetns);
@@ -3198,7 +3202,7 @@ xml_xmlnodetoxmltype(xmlNodePtr cur)
 	{
 		str = xmlXPathCastNodeToString(cur);
 		len = strlen((char *) str);
-		result = (text *) palloc(len + VARHDRSZ);
+		result = (xmltype *) palloc(len + VARHDRSZ);
 		SET_VARSIZE(result, len + VARHDRSZ);
 		memcpy(VARDATA(result), str, len);
 	}
@@ -3363,8 +3367,8 @@ xpath(PG_FUNCTION_ARGS)
 				ereport(ERROR,
 						(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
 						 errmsg("neither namespace name nor URI may be null")));
-			ns_name = _textout(ns_names_uris[i * 2]);
-			ns_uri = _textout(ns_names_uris[i * 2 + 1]);
+			ns_name = TextDatumGetCString(ns_names_uris[i * 2]);
+			ns_uri = TextDatumGetCString(ns_names_uris[i * 2 + 1]);
 			if (xmlXPathRegisterNs(xpathctx,
 								   (xmlChar *) ns_name,
 								   (xmlChar *) ns_uri) != 0)