Fix encoding handling in xml binary input function. If the XML header didn't

specify an encoding explicitly, we used to treat it as being in database
encoding when we parsed it, but then perform a UTF-8 -> database encoding
conversion on it, which was completely bogus. It's now consistently treated as
UTF-8.

Author: hlinnaka

src/backend/utils/adt/xml.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.93 2009/08/10 05:46:50 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.94 2009/09/04 10:49:29 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -109,7 +109,7 @@ static int parse_xml_decl(const xmlChar *str, size_t *lenp,
 static bool print_xml_decl(StringInfo buf, const xmlChar *version,
 			   pg_enc encoding, int standalone);
 static xmlDocPtr xml_parse(text *data, XmlOptionType xmloption_arg,
-		  bool preserve_whitespace, xmlChar *encoding);
+		  bool preserve_whitespace, int encoding);
 static text *xml_xmlnodetoxmltype(xmlNodePtr cur);
 #endif   /* USE_LIBXML */
 
@@ -183,7 +183,7 @@ xml_in(PG_FUNCTION_ARGS)
 	 * Parse the data to check if it is well-formed XML data.  Assume that
 	 * ERROR occurred if parsing failed.
 	 */
-	doc = xml_parse(vardata, xmloption, true, NULL);
+	doc = xml_parse(vardata, xmloption, true, GetDatabaseEncoding());
 	xmlFreeDoc(doc);
 
 	PG_RETURN_XML_P(vardata);
@@ -272,7 +272,8 @@ xml_recv(PG_FUNCTION_ARGS)
 	char	   *newstr;
 	int			nbytes;
 	xmlDocPtr	doc;
-	xmlChar    *encoding = NULL;
+	xmlChar    *encodingStr = NULL;
+	int			encoding;
 
 	/*
 	 * Read the data in raw format. We don't know yet what the encoding is, as
@@ -293,7 +294,15 @@ xml_recv(PG_FUNCTION_ARGS)
 	str = VARDATA(result);
 	str[nbytes] = '\0';
 
-	parse_xml_decl((xmlChar *) str, NULL, NULL, &encoding, NULL);
+	parse_xml_decl((xmlChar *) str, NULL, NULL, &encodingStr, NULL);
+
+	/*
+	 * If encoding wasn't explicitly specified in the XML header, treat it as
+	 * UTF-8, as that's the default in XML. This is different from xml_in(),
+	 * where the input has to go through the normal client to server encoding
+	 * conversion.
+	 */
+	encoding = encodingStr ? xmlChar_to_encoding(encodingStr) : PG_UTF8;
 
 	/*
 	 * Parse the data to check if it is well-formed XML data.  Assume that
@@ -305,9 +314,7 @@ xml_recv(PG_FUNCTION_ARGS)
 	/* Now that we know what we're dealing with, convert to server encoding */
 	newstr = (char *) pg_do_encoding_conversion((unsigned char *) str,
 												nbytes,
-												encoding ?
-											  xmlChar_to_encoding(encoding) :
-												PG_UTF8,
+												encoding,
 												GetDatabaseEncoding());
 
 	if (newstr != str)
@@ -659,7 +666,8 @@ xmlparse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace)
 #ifdef USE_LIBXML
 	xmlDocPtr	doc;
 
-	doc = xml_parse(data, xmloption_arg, preserve_whitespace, NULL);
+	doc = xml_parse(data, xmloption_arg, preserve_whitespace,
+					GetDatabaseEncoding());
 	xmlFreeDoc(doc);
 
 	return (xmltype *) data;
@@ -799,7 +807,8 @@ xml_is_document(xmltype *arg)
 	/* We want to catch ereport(INVALID_XML_DOCUMENT) and return false */
 	PG_TRY();
 	{
-		doc = xml_parse((text *) arg, XMLOPTION_DOCUMENT, true, NULL);
+		doc = xml_parse((text *) arg, XMLOPTION_DOCUMENT, true,
+						GetDatabaseEncoding());
 		result = true;
 	}
 	PG_CATCH();
@@ -1152,7 +1161,7 @@ print_xml_decl(StringInfo buf, const xmlChar *version,
  */
 static xmlDocPtr
 xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
-		  xmlChar *encoding)
+		  int encoding)
 {
 	int32		len;
 	xmlChar    *string;
@@ -1165,9 +1174,7 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
 
 	utf8string = pg_do_encoding_conversion(string,
 										   len,
-										   encoding ?
-										   xmlChar_to_encoding(encoding) :
-										   GetDatabaseEncoding(),
+										   encoding,
 										   PG_UTF8);
 
 	/* Start up libxml and its parser (no-ops if already done) */