From d830b88ed345a631242708139854692de0e727b8 Mon Sep 17 00:00:00 2001 From: Jim Jones Date: Mon, 9 Nov 2026 09:59:02 +0100 Subject: [PATCH v1] Omit the XML declaration of xml values embedded as element content xmlelement(), xmlforest() and the query_to_xml() family copied the XML declaration of an xml argument into the element whenever xml_out() would print it, i.e. for a standalone property or a version other than 1.0. A declaration is only allowed at the start of a document, so the result could not be read back by xml_in(). Add a flag to xml_out_internal() to omit the declaration, and use it in map_sql_value_to_xml_value() for xml values used as element content. --- src/backend/utils/adt/xml.c | 20 +++++++++++++++----- src/test/regress/expected/xml.out | 19 +++++++++++++++++++ src/test/regress/sql/xml.sql | 4 ++++ 3 files changed, 38 insertions(+), 5 deletions(-) diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c index 44a3a21d135..91f0bba9766 100644 --- a/src/backend/utils/adt/xml.c +++ b/src/backend/utils/adt/xml.c @@ -305,9 +305,11 @@ xml_in(PG_FUNCTION_ARGS) * * This is only acceptable so long as xmltype and text use the same * representation. + * + * If omit_xmldecl is true, no XML declaration is printed. */ static char * -xml_out_internal(xmltype *x, pg_enc target_encoding) +xml_out_internal(xmltype *x, pg_enc target_encoding, bool omit_xmldecl) { char *str = text_to_cstring((text *) x); @@ -324,7 +326,8 @@ xml_out_internal(xmltype *x, pg_enc target_encoding) initStringInfo(&buf); - if (!print_xml_decl(&buf, version, target_encoding, standalone)) + if (omit_xmldecl || + !print_xml_decl(&buf, version, target_encoding, standalone)) { /* * If we are not going to produce an XML declaration, eat a single @@ -361,7 +364,7 @@ xml_out(PG_FUNCTION_ARGS) * different client encoding, so we'd do more harm than good by including * it. */ - PG_RETURN_CSTRING(xml_out_internal(x, 0)); + PG_RETURN_CSTRING(xml_out_internal(x, 0, false)); } @@ -444,7 +447,7 @@ xml_send(PG_FUNCTION_ARGS) * xml_out_internal doesn't convert the encoding, it just prints the right * declaration. pq_sendtext will do the conversion. */ - outval = xml_out_internal(x, pg_get_client_encoding()); + outval = xml_out_internal(x, pg_get_client_encoding(), false); pq_begintypsend(&buf); pq_sendtext(&buf, outval, strlen(outval)); @@ -2725,6 +2728,13 @@ map_sql_value_to_xml_value(Datum value, Oid type, bool xml_escape_strings) } + /* + * An XML declaration is only allowed at the start of a document, so + * omit it from xml values used as element content. + */ + if (type == XMLOID && xml_escape_strings) + return xml_out_internal(DatumGetXmlP(value), 0, true); + /* * otherwise, just use the type's native text representation */ @@ -4836,7 +4846,7 @@ XmlTableSetDocument(TableFuncScanState *state, Datum value) * Use out function for casting to string (remove encoding property). See * comment in xml_out. */ - str = xml_out_internal(xmlval, 0); + str = xml_out_internal(xmlval, 0, false); length = strlen(str); xstr = pg_xmlCharStrndup(str, length); diff --git a/src/test/regress/expected/xml.out b/src/test/regress/expected/xml.out index 6998745ee03..66c0ac763c7 100644 --- a/src/test/regress/expected/xml.out +++ b/src/test/regress/expected/xml.out @@ -190,6 +190,25 @@ SELECT xmlelement(name foo, xml 'br'); br (1 row) +-- an XML declaration is not kept when an xml value is embedded as content +SELECT xmlelement(name foo, ''::xml); + xmlelement +----------------- + +(1 row) + +SELECT xmlforest(''::xml AS foo); + xmlforest +----------------- + +(1 row) + +SELECT xmlelement(name foo, array[''::xml]); + xmlelement +------------------------------------ + +(1 row) + SELECT xmlelement(name foo, array[1, 2, 3]); xmlelement ------------------------------------------------------------------------- diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql index 0581d21b03f..ce38a19bafb 100644 --- a/src/test/regress/sql/xml.sql +++ b/src/test/regress/sql/xml.sql @@ -62,6 +62,10 @@ SELECT xmlelement(name foo, text 'bar'); SELECT xmlelement(name foo, xml 'bar'); SELECT xmlelement(name foo, text 'br'); SELECT xmlelement(name foo, xml 'br'); +-- an XML declaration is not kept when an xml value is embedded as content +SELECT xmlelement(name foo, ''::xml); +SELECT xmlforest(''::xml AS foo); +SELECT xmlelement(name foo, array[''::xml]); SELECT xmlelement(name foo, array[1, 2, 3]); SET xmlbinary TO base64; SELECT xmlelement(name foo, bytea 'bar'); -- 2.56.0