From 526fe0d79914b2dfcfd79effd1ab26ff62469248 Mon Sep 17 00:00:00 2001 From: Daniel Gustafsson Date: Mon, 6 Nov 2023 09:38:29 +0100 Subject: [PATCH] Add XMLText function (SQL/XML X038) This function implements the standard XMLTest function, which converts text into xml text nodes. It uses the libxml2 function xmlEncodeSpecialChars to escape predefined entities (&"<>), so that those do not cause any conflict when concatenating the text node output with existing xml documents. This also adds a note in features.sgml about not supporting XML(SEQUENCE). The SQL specification defines a RETURNING clause to a set of XML functions, where RETURNING CONTENT or RETURNING SEQUENCE can be defined. Since PostgreSQL doesn't support XML(SEQUENCE) all of these functions operate with an implicit RETURNING CONTENT. Author: Jim Jones Reviewed-by: Vik Fearing Discussion: https://postgr.es/m/86617a66-ec95-581f-8d54-08059cca8885@uni-muenster.de --- doc/src/sgml/features.sgml | 9 +++++++ doc/src/sgml/func.sgml | 30 +++++++++++++++++++++++ src/backend/catalog/sql_features.txt | 2 +- src/backend/utils/adt/xml.c | 22 +++++++++++++++++ src/include/catalog/pg_proc.dat | 3 +++ src/test/regress/expected/xml.out | 36 ++++++++++++++++++++++++++++ src/test/regress/expected/xml_1.out | 23 ++++++++++++++++++ src/test/regress/expected/xml_2.out | 36 ++++++++++++++++++++++++++++ src/test/regress/sql/xml.sql | 7 ++++++ 9 files changed, 167 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/features.sgml b/doc/src/sgml/features.sgml index 575afa3476..966fd39882 100644 --- a/doc/src/sgml/features.sgml +++ b/doc/src/sgml/features.sgml @@ -199,6 +199,15 @@ standard. + + + + PostgreSQL does not support the + RETURNING CONTENT or RETURNING SEQUENCE + clauses, functions which are defined to have these in the specification + are implicitly returning content. + + diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index a6fcac0824..d963f0a0a0 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -14180,6 +14180,36 @@ CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple documents for processing in client applications. + + <literal>xmltext</literal> + + + xmltext + + + +xmltext ( text ) xml + + + + The function xmltext returns an XML value with a single + text node containing the input argument as its content. Predefined entities + like ampersand (), left and right angle brackets + (]]>), and quotation marks () + are escaped. + + + + Example: +'); + xmltext +------------------------- + < foo & bar > +]]> + + + <literal>xmlcomment</literal> diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt index b33065d7bf..80c40eaf57 100644 --- a/src/backend/catalog/sql_features.txt +++ b/src/backend/catalog/sql_features.txt @@ -633,7 +633,7 @@ X034 XMLAgg YES X035 XMLAgg: ORDER BY option YES X036 XMLComment YES X037 XMLPI YES -X038 XMLText NO +X038 XMLText YES supported except for RETURNING X040 Basic table mapping YES X041 Basic table mapping: null absent YES X042 Basic table mapping: null as nil YES diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c index 2300c7ebf3..c401e7b821 100644 --- a/src/backend/utils/adt/xml.c +++ b/src/backend/utils/adt/xml.c @@ -47,6 +47,7 @@ #ifdef USE_LIBXML #include +#include #include #include #include @@ -513,6 +514,27 @@ xmlcomment(PG_FUNCTION_ARGS) } +Datum +xmltext(PG_FUNCTION_ARGS) +{ +#ifdef USE_LIBXML + text *arg = PG_GETARG_TEXT_PP(0); + text *result; + xmlChar *xmlbuf = NULL; + + xmlbuf = xmlEncodeSpecialChars(NULL, xml_text2xmlChar(arg)); + + Assert(xmlbuf); + + result = cstring_to_text_with_len((const char *) xmlbuf, xmlStrlen(xmlbuf)); + xmlFree(xmlbuf); + PG_RETURN_XML_P(result); +#else + NO_XML_SUPPORT(); + return 0; +#endif /* not USE_LIBXML */ +} + /* * TODO: xmlconcat needs to merge the notations and unparsed entities diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 091f7e343c..f14aed422a 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -8793,6 +8793,9 @@ { oid => '2922', descr => 'serialize an XML value to a character string', proname => 'text', prorettype => 'text', proargtypes => 'xml', prosrc => 'xmltotext' }, +{ oid => '3813', descr => 'generate XML text node', + proname => 'xmltext', proisstrict => 't', prorettype => 'xml', + proargtypes => 'text', prosrc => 'xmltext' }, { oid => '2923', descr => 'map table contents to XML', proname => 'table_to_xml', procost => '100', provolatile => 's', diff --git a/src/test/regress/expected/xml.out b/src/test/regress/expected/xml.out index 398345ca67..13e4296bf8 100644 --- a/src/test/regress/expected/xml.out +++ b/src/test/regress/expected/xml.out @@ -1785,3 +1785,39 @@ SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH | <foo/> (1 row) +SELECT xmltext(NULL); + xmltext +--------- + +(1 row) + +SELECT xmltext(''); + xmltext +--------- + +(1 row) + +SELECT xmltext(' '); + xmltext +--------- + +(1 row) + +SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}'); + xmltext +-------------------------- + foo `$_-+?=*^%!|/\()[]{} +(1 row) + +SELECT xmltext('foo & <"bar">'); + xmltext +----------------------------------- + foo & <"bar"> +(1 row) + +SELECT xmltext('x'|| '

73

'::xml || .42 || true || 'j'::char); + xmltext +--------------------------------- + x<P>73</P>0.42truej +(1 row) + diff --git a/src/test/regress/expected/xml_1.out b/src/test/regress/expected/xml_1.out index 63b779470f..eb9c6f2ed4 100644 --- a/src/test/regress/expected/xml_1.out +++ b/src/test/regress/expected/xml_1.out @@ -1402,3 +1402,26 @@ DETAIL: This functionality requires the server to be built with libxml support. SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH '""', b xml PATH '""'); ERROR: unsupported XML feature DETAIL: This functionality requires the server to be built with libxml support. +SELECT xmltext(NULL); + xmltext +--------- + +(1 row) + +SELECT xmltext(''); +ERROR: unsupported XML feature +DETAIL: This functionality requires the server to be built with libxml support. +SELECT xmltext(' '); +ERROR: unsupported XML feature +DETAIL: This functionality requires the server to be built with libxml support. +SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}'); +ERROR: unsupported XML feature +DETAIL: This functionality requires the server to be built with libxml support. +SELECT xmltext('foo & <"bar">'); +ERROR: unsupported XML feature +DETAIL: This functionality requires the server to be built with libxml support. +SELECT xmltext('x'|| '

73

'::xml || .42 || true || 'j'::char); +ERROR: unsupported XML feature +LINE 1: SELECT xmltext('x'|| '

73

'::xml || .42 || true || 'j':... + ^ +DETAIL: This functionality requires the server to be built with libxml support. diff --git a/src/test/regress/expected/xml_2.out b/src/test/regress/expected/xml_2.out index 43c2558352..c8ed8e0cfa 100644 --- a/src/test/regress/expected/xml_2.out +++ b/src/test/regress/expected/xml_2.out @@ -1765,3 +1765,39 @@ SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH | <foo/> (1 row) +SELECT xmltext(NULL); + xmltext +--------- + +(1 row) + +SELECT xmltext(''); + xmltext +--------- + +(1 row) + +SELECT xmltext(' '); + xmltext +--------- + +(1 row) + +SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}'); + xmltext +-------------------------- + foo `$_-+?=*^%!|/\()[]{} +(1 row) + +SELECT xmltext('foo & <"bar">'); + xmltext +----------------------------------- + foo & <"bar"> +(1 row) + +SELECT xmltext('x'|| '

73

'::xml || .42 || true || 'j'::char); + xmltext +--------------------------------- + x<P>73</P>0.42truej +(1 row) + diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql index a591eea2e5..bd4a4e7acd 100644 --- a/src/test/regress/sql/xml.sql +++ b/src/test/regress/sql/xml.sql @@ -660,3 +660,10 @@ SELECT * FROM XMLTABLE('*' PASSING 'pre"', b xml PATH '""'); + +SELECT xmltext(NULL); +SELECT xmltext(''); +SELECT xmltext(' '); +SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}'); +SELECT xmltext('foo & <"bar">'); +SELECT xmltext('x'|| '

73

'::xml || .42 || true || 'j'::char); \ No newline at end of file