rebased due to recent changes in func-xml.sgml
Additionally, v19 now wraps the xmlC14NDocDumpMemory call in a
PG_TRY/PG_CATCH.
Best regards, Jim
From 64c37bc75a14dadf1ae3fc1daa2112dfa89efd06 Mon Sep 17 00:00:00 2001
From: Jim Jones <jim.jo...@uni-muenster.de>
Date: Wed, 6 Aug 2025 17:31:57 +0200
Subject: [PATCH v19] Add xmlcanonicalize function
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
This patch adds the xmlcanonicalize(xml, boolean) function, which
transforms a well-formed XML document into its canonical form
according to the W3C Canonical XML 1.1 (C14N 1.1) specification.
xmlcanonicalize(doc xml, keep_comments boolean DEFAULT true) RETURNS xml
- doc: the XML document to be canonicalized.
- keep_comments: whether to preserve XML comments (default: true).
This function is implemented using the xmlC14NDocDumpMemory()
function from libxml2’s Canonical XML (C14N) module.
---
doc/src/sgml/func/func-xml.sgml | 50 +++++++++++++++
src/backend/catalog/system_functions.sql | 6 ++
src/backend/utils/adt/xml.c | 81 +++++++++++++++++++++++
src/include/catalog/pg_proc.dat | 3 +
src/test/regress/expected/xml.out | 82 ++++++++++++++++++++++++
src/test/regress/expected/xml_1.out | 80 +++++++++++++++++++++++
src/test/regress/expected/xml_2.out | 82 ++++++++++++++++++++++++
src/test/regress/sql/xml.sql | 52 +++++++++++++++
8 files changed, 436 insertions(+)
diff --git a/doc/src/sgml/func/func-xml.sgml b/doc/src/sgml/func/func-xml.sgml
index 21f34467a4..0e958bda2e 100644
--- a/doc/src/sgml/func/func-xml.sgml
+++ b/doc/src/sgml/func/func-xml.sgml
@@ -61,6 +61,56 @@ SELECT xmltext('< foo & bar >');
</para>
</sect3>
+<sect3 id="functions-producing-xml-xmlcanonicalize">
+ <title><literal>xmlcanonicalize</literal></title>
+
+ <indexterm>
+ <primary>xmlcanonicalize</primary>
+ </indexterm>
+
+<synopsis>
+<function>xmlcanonicalize</function> ( <parameter>doc</parameter> <type>xml</type> [, <parameter>keep_comments</parameter> <type>boolean</type> DEFAULT <literal>true</literal>] ) <returnvalue>xml</returnvalue>
+
+</synopsis>
+
+ <para>
+ This function transforms a given XML document into its <ulink url="https://www.w3.org/TR/xml-c14n11/#Terminology";>canonical form</ulink>,
+ as defined by the <ulink url="https://www.w3.org/TR/xml-c14n11/";>W3C Canonical XML 1.1 Specification</ulink>, which standardizes the document's
+ structure and syntax to facilitate comparison and validation.
+ The <parameter>keep_comments</parameter> parameter controls whether XML comments from the input document are preserved or discarded.
+ If omitted, it defaults to <literal>true</literal>.
+ </para>
+
+ <para>
+ Example:
+<screen><![CDATA[
+SELECT
+ xmlcanonicalize(
+ '<foo>
+ <!-- a comment -->
+ <bar c="3" b="2" a="1">42</bar>
+ <empty/>
+ </foo>'::xml);
+ xmlcanonicalize
+-----------------------------------------------------------------------------
+ <foo><!-- a comment --><bar a="1" b="2" c="3">42</bar><empty></empty></foo>
+(1 row)
+
+SELECT
+ xmlcanonicalize(
+ '<foo>
+ <!-- a comment -->
+ <bar c="3" b="2" a="1">42</bar>
+ <empty/>
+ </foo>'::xml, false);
+ xmlcanonicalize
+-----------------------------------------------------------
+ <foo><bar a="1" b="2" c="3">42</bar><empty></empty></foo>
+(1 row)
+]]></screen>
+ </para>
+ </sect3>
+
<sect3 id="functions-producing-xml-xmlcomment">
<title><literal>xmlcomment</literal></title>
diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql
index 566f308e44..15c33335dc 100644
--- a/src/backend/catalog/system_functions.sql
+++ b/src/backend/catalog/system_functions.sql
@@ -268,6 +268,12 @@ CREATE OR REPLACE FUNCTION xpath_exists(text, xml)
IMMUTABLE PARALLEL SAFE STRICT COST 1
RETURN xpath_exists($1, $2, '{}'::text[]);
+CREATE OR REPLACE FUNCTION xmlcanonicalize(xml, boolean DEFAULT true)
+ RETURNS xml
+ LANGUAGE internal
+ IMMUTABLE PARALLEL SAFE STRICT
+AS 'xmlcanonicalize';
+
CREATE OR REPLACE FUNCTION pg_sleep_for(interval)
RETURNS void
LANGUAGE sql
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index 182e8f75db..0a4aa64ec2 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -58,6 +58,7 @@
#include <libxml/xmlwriter.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
+#include <libxml/c14n.h>
/*
* We used to check for xmlStructuredErrorContext via a configure test; but
@@ -566,6 +567,86 @@ xmltext(PG_FUNCTION_ARGS)
#endif /* not USE_LIBXML */
}
+/*
+ * Canonicalizes the given XML document according to the W3C Canonical XML 1.1
+ * specification, using libxml2's xmlC14NDocDumpMemory().
+ *
+ * The input XML must be a well-formed document (not a fragment). The
+ * canonical form is deterministic and useful for digital signatures and
+ * comparing logically equivalent XML.
+ *
+ * The second argument determines whether comments are preserved
+ * (true) or omitted (false) in the canonicalized output.
+ */
+Datum xmlcanonicalize(PG_FUNCTION_ARGS)
+{
+#ifdef USE_LIBXML
+ xmltype *arg = PG_GETARG_XML_P(0);
+ bool keep_comments = PG_GETARG_BOOL(1);
+ text *result;
+ volatile xmlChar *xmlbuf = NULL;
+ volatile int nbytes = 0;
+ volatile xmlDocPtr doc = NULL;
+ PgXmlErrorContext *xmlerrcxt;
+
+ /* Set up XML error context for proper libxml2 error integration */
+ xmlerrcxt = pg_xml_init(PG_XML_STRICTNESS_ALL);
+
+ PG_TRY();
+ {
+ /* Parse the input as a full XML document */
+ doc = xml_parse(arg, XMLOPTION_DOCUMENT, false,
+ GetDatabaseEncoding(), NULL, NULL, (Node *)xmlerrcxt);
+
+ /*
+ * xmlC14NDocDumpMemory arguments:
+ * - doc: the XML document to canonicalize (already parsed above)
+ * - nodes: NULL means the entire document is canonicalized
+ * - mode: 2 selects the Canonical XML 1.1 algorithm (xmlC14NMode enum)
+ * - inclusive_ns_prefixes: NULL includes all namespaces by default
+ * - with_comments: determined by keep_comments argument
+ * - doc_txt_ptr: output buffer receiving the canonicalized XML (xmlbuf)
+ *
+ * On success, xmlbuf points to the serialized canonical form, and nbytes
+ * holds its size.
+ */
+ nbytes = xmlC14NDocDumpMemory(doc,
+ NULL, /* entire document */
+ 2, /* xmlC14NMode 1.1 */
+ NULL, /* all namespaces */
+ keep_comments,
+ (xmlChar **)&xmlbuf);
+
+ if (nbytes < 0 || xmlbuf == NULL || xmlerrcxt->err_occurred)
+ xml_ereport(xmlerrcxt, ERROR, ERRCODE_INTERNAL_ERROR,
+ "could not canonicalize XML document");
+
+ result = cstring_to_text_with_len((const char *)xmlbuf, nbytes);
+ }
+ PG_CATCH();
+ {
+ if (doc)
+ xmlFreeDoc((xmlDocPtr)doc);
+ if (xmlbuf)
+ xmlFree((xmlChar *)xmlbuf);
+
+ pg_xml_done(xmlerrcxt, true);
+ PG_RE_THROW();
+ }
+ PG_END_TRY();
+
+ if (doc)
+ xmlFreeDoc((xmlDocPtr)doc);
+ if (xmlbuf)
+ xmlFree((xmlChar *)xmlbuf);
+ pg_xml_done(xmlerrcxt, false);
+
+ 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 118d6da1ac..d16b118c7d 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -9159,6 +9159,9 @@
{ oid => '3813', descr => 'generate XML text node',
proname => 'xmltext', prorettype => 'xml', proargtypes => 'text',
prosrc => 'xmltext' },
+{ oid => '3814', descr => 'generate the canonical form of an XML document',
+ proname => 'xmlcanonicalize', prorettype => 'xml', proargtypes => 'xml bool',
+ prosrc => 'xmlcanonicalize' },
{ 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 103a22a3b1..688c0fc3e9 100644
--- a/src/test/regress/expected/xml.out
+++ b/src/test/regress/expected/xml.out
@@ -1881,3 +1881,85 @@ SELECT xmltext('x'|| '<P>73</P>'::xml || .42 || true || 'j'::char);
x<P>73</P>0.42truej
(1 row)
+-- xmlserialize: canonical
+CREATE TABLE xmlcanonicalize_test (doc xml);
+INSERT INTO xmlcanonicalize_test VALUES
+ ('<?xml version="1.0" encoding="ISO-8859-1"?>
+ <!DOCTYPE doc SYSTEM "doc.dtd" [
+ <!ENTITY val "42">
+ <!ATTLIST xyz attr CDATA "default">
+ ]>
+
+ <!-- attributes and namespces will be sorted -->
+ <foo a:attr="out" b:attr="sorted" attr2="all" attr="I am"
+ xmlns:b="http://www.ietf.org";
+ xmlns:a="http://www.w3.org";
+ xmlns="http://example.org";>
+
+ <!-- Normalization of whitespace in start and end tags -->
+ <!-- Elimination of superfluous namespace declarations, as already declared in <foo> -->
+ <bar xmlns="" xmlns:a="http://www.w3.org"; >&val;</bar >
+
+ <!-- empty element will be converted to start-end tag pair -->
+ <empty/>
+
+ <!-- text will be transcoded to UTF-8 -->
+ <transcode>1</transcode>
+
+ <!-- whitespace inside tag will be preserved -->
+ <whitespace> 321 </whitespace>
+
+ <!-- empty namespace will be removed of child tag -->
+ <emptyns xmlns="" >
+ <emptyns_child xmlns=""></emptyns_child>
+ </emptyns>
+
+ <!-- CDATA section will be replaced by its value -->
+ <compute><![CDATA[value>"0" && value<"10" ?"valid":"error"]]></compute>
+ </foo> <!-- comment outside root element --> ');
+SELECT xmlcanonicalize(doc, true) FROM xmlcanonicalize_test;
+ xmlcanonicalize
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ <!-- attributes and namespces will be sorted --> +
+ <foo xmlns="http://example.org"; xmlns:a="http://www.w3.org"; xmlns:b="http://www.ietf.org"; attr="I am" attr2="all" b:attr="sorted" a:attr="out"><!-- Normalization of whitespace in start and end tags --><!-- Elimination of superfluous namespace declarations, as already declared in <foo> --><bar xmlns="">42</bar><!-- empty element will be converted to start-end tag pair --><empty></empty><!-- text will be transcoded to UTF-8 --><transcode>1</transcode><!-- whitespace inside tag will be preserved --><whitespace> 321 </whitespace><!-- empty namespace will be removed of child tag --><emptyns xmlns=""><emptyns_child></emptyns_child></emptyns><!-- CDATA section will be replaced by its value --><compute>value>"0" && value<"10" ?"valid":"error"</compute></foo>+
+ <!-- comment outside root element -->
+(1 row)
+
+SELECT xmlcanonicalize(doc, false) FROM xmlcanonicalize_test;
+ xmlcanonicalize
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ <foo xmlns="http://example.org"; xmlns:a="http://www.w3.org"; xmlns:b="http://www.ietf.org"; attr="I am" attr2="all" b:attr="sorted" a:attr="out"><bar xmlns="">42</bar><empty></empty><transcode>1</transcode><whitespace> 321 </whitespace><emptyns xmlns=""><emptyns_child></emptyns_child></emptyns><compute>value>"0" && value<"10" ?"valid":"error"</compute></foo>
+(1 row)
+
+SELECT xmlcanonicalize(doc, true)::text = xmlcanonicalize(doc)::text FROM xmlcanonicalize_test;
+ ?column?
+----------
+ t
+(1 row)
+
+SELECT xmlcanonicalize(doc, NULL) FROM xmlcanonicalize_test;
+ xmlcanonicalize
+-----------------
+
+(1 row)
+
+SELECT xmlcanonicalize(NULL, true);
+ xmlcanonicalize
+-----------------
+
+(1 row)
+
+\set VERBOSITY terse
+SELECT xmlcanonicalize('', true);
+ERROR: invalid XML document
+SELECT xmlcanonicalize(' ', true);
+ERROR: invalid XML document
+SELECT xmlcanonicalize('foo', true);
+ERROR: invalid XML document
+SELECT xmlcanonicalize('');
+ERROR: invalid XML document
+SELECT xmlcanonicalize(' ');
+ERROR: invalid XML document
+SELECT xmlcanonicalize('foo');
+ERROR: invalid XML document
+\set VERBOSITY default
diff --git a/src/test/regress/expected/xml_1.out b/src/test/regress/expected/xml_1.out
index 73c411118a..8bc3ac1c96 100644
--- a/src/test/regress/expected/xml_1.out
+++ b/src/test/regress/expected/xml_1.out
@@ -1496,3 +1496,83 @@ ERROR: unsupported XML feature
LINE 1: SELECT xmltext('x'|| '<P>73</P>'::xml || .42 || true || 'j':...
^
DETAIL: This functionality requires the server to be built with libxml support.
+-- xmlserialize: canonical
+CREATE TABLE xmlcanonicalize_test (doc xml);
+INSERT INTO xmlcanonicalize_test VALUES
+ ('<?xml version="1.0" encoding="ISO-8859-1"?>
+ <!DOCTYPE doc SYSTEM "doc.dtd" [
+ <!ENTITY val "42">
+ <!ATTLIST xyz attr CDATA "default">
+ ]>
+
+ <!-- attributes and namespces will be sorted -->
+ <foo a:attr="out" b:attr="sorted" attr2="all" attr="I am"
+ xmlns:b="http://www.ietf.org";
+ xmlns:a="http://www.w3.org";
+ xmlns="http://example.org";>
+
+ <!-- Normalization of whitespace in start and end tags -->
+ <!-- Elimination of superfluous namespace declarations, as already declared in <foo> -->
+ <bar xmlns="" xmlns:a="http://www.w3.org"; >&val;</bar >
+
+ <!-- empty element will be converted to start-end tag pair -->
+ <empty/>
+
+ <!-- text will be transcoded to UTF-8 -->
+ <transcode>1</transcode>
+
+ <!-- whitespace inside tag will be preserved -->
+ <whitespace> 321 </whitespace>
+
+ <!-- empty namespace will be removed of child tag -->
+ <emptyns xmlns="" >
+ <emptyns_child xmlns=""></emptyns_child>
+ </emptyns>
+
+ <!-- CDATA section will be replaced by its value -->
+ <compute><![CDATA[value>"0" && value<"10" ?"valid":"error"]]></compute>
+ </foo> <!-- comment outside root element --> ');
+ERROR: unsupported XML feature
+LINE 2: ('<?xml version="1.0" encoding="ISO-8859-1"?>
+ ^
+DETAIL: This functionality requires the server to be built with libxml support.
+SELECT xmlcanonicalize(doc, true) FROM xmlcanonicalize_test;
+ xmlcanonicalize
+-----------------
+(0 rows)
+
+SELECT xmlcanonicalize(doc, false) FROM xmlcanonicalize_test;
+ xmlcanonicalize
+-----------------
+(0 rows)
+
+SELECT xmlcanonicalize(doc, true)::text = xmlcanonicalize(doc)::text FROM xmlcanonicalize_test;
+ ?column?
+----------
+(0 rows)
+
+SELECT xmlcanonicalize(doc, NULL) FROM xmlcanonicalize_test;
+ xmlcanonicalize
+-----------------
+(0 rows)
+
+SELECT xmlcanonicalize(NULL, true);
+ xmlcanonicalize
+-----------------
+
+(1 row)
+
+\set VERBOSITY terse
+SELECT xmlcanonicalize('', true);
+ERROR: unsupported XML feature at character 24
+SELECT xmlcanonicalize(' ', true);
+ERROR: unsupported XML feature at character 24
+SELECT xmlcanonicalize('foo', true);
+ERROR: unsupported XML feature at character 24
+SELECT xmlcanonicalize('');
+ERROR: unsupported XML feature at character 24
+SELECT xmlcanonicalize(' ');
+ERROR: unsupported XML feature at character 24
+SELECT xmlcanonicalize('foo');
+ERROR: unsupported XML feature at character 24
+\set VERBOSITY default
diff --git a/src/test/regress/expected/xml_2.out b/src/test/regress/expected/xml_2.out
index a85d95358d..4ce36ff825 100644
--- a/src/test/regress/expected/xml_2.out
+++ b/src/test/regress/expected/xml_2.out
@@ -1867,3 +1867,85 @@ SELECT xmltext('x'|| '<P>73</P>'::xml || .42 || true || 'j'::char);
x<P>73</P>0.42truej
(1 row)
+-- xmlserialize: canonical
+CREATE TABLE xmlcanonicalize_test (doc xml);
+INSERT INTO xmlcanonicalize_test VALUES
+ ('<?xml version="1.0" encoding="ISO-8859-1"?>
+ <!DOCTYPE doc SYSTEM "doc.dtd" [
+ <!ENTITY val "42">
+ <!ATTLIST xyz attr CDATA "default">
+ ]>
+
+ <!-- attributes and namespces will be sorted -->
+ <foo a:attr="out" b:attr="sorted" attr2="all" attr="I am"
+ xmlns:b="http://www.ietf.org";
+ xmlns:a="http://www.w3.org";
+ xmlns="http://example.org";>
+
+ <!-- Normalization of whitespace in start and end tags -->
+ <!-- Elimination of superfluous namespace declarations, as already declared in <foo> -->
+ <bar xmlns="" xmlns:a="http://www.w3.org"; >&val;</bar >
+
+ <!-- empty element will be converted to start-end tag pair -->
+ <empty/>
+
+ <!-- text will be transcoded to UTF-8 -->
+ <transcode>1</transcode>
+
+ <!-- whitespace inside tag will be preserved -->
+ <whitespace> 321 </whitespace>
+
+ <!-- empty namespace will be removed of child tag -->
+ <emptyns xmlns="" >
+ <emptyns_child xmlns=""></emptyns_child>
+ </emptyns>
+
+ <!-- CDATA section will be replaced by its value -->
+ <compute><![CDATA[value>"0" && value<"10" ?"valid":"error"]]></compute>
+ </foo> <!-- comment outside root element --> ');
+SELECT xmlcanonicalize(doc, true) FROM xmlcanonicalize_test;
+ xmlcanonicalize
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ <!-- attributes and namespces will be sorted --> +
+ <foo xmlns="http://example.org"; xmlns:a="http://www.w3.org"; xmlns:b="http://www.ietf.org"; attr="I am" attr2="all" b:attr="sorted" a:attr="out"><!-- Normalization of whitespace in start and end tags --><!-- Elimination of superfluous namespace declarations, as already declared in <foo> --><bar xmlns="">42</bar><!-- empty element will be converted to start-end tag pair --><empty></empty><!-- text will be transcoded to UTF-8 --><transcode>1</transcode><!-- whitespace inside tag will be preserved --><whitespace> 321 </whitespace><!-- empty namespace will be removed of child tag --><emptyns xmlns=""><emptyns_child></emptyns_child></emptyns><!-- CDATA section will be replaced by its value --><compute>value>"0" && value<"10" ?"valid":"error"</compute></foo>+
+ <!-- comment outside root element -->
+(1 row)
+
+SELECT xmlcanonicalize(doc, false) FROM xmlcanonicalize_test;
+ xmlcanonicalize
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ <foo xmlns="http://example.org"; xmlns:a="http://www.w3.org"; xmlns:b="http://www.ietf.org"; attr="I am" attr2="all" b:attr="sorted" a:attr="out"><bar xmlns="">42</bar><empty></empty><transcode>1</transcode><whitespace> 321 </whitespace><emptyns xmlns=""><emptyns_child></emptyns_child></emptyns><compute>value>"0" && value<"10" ?"valid":"error"</compute></foo>
+(1 row)
+
+SELECT xmlcanonicalize(doc, true)::text = xmlcanonicalize(doc)::text FROM xmlcanonicalize_test;
+ ?column?
+----------
+ t
+(1 row)
+
+SELECT xmlcanonicalize(doc, NULL) FROM xmlcanonicalize_test;
+ xmlcanonicalize
+-----------------
+
+(1 row)
+
+SELECT xmlcanonicalize(NULL, true);
+ xmlcanonicalize
+-----------------
+
+(1 row)
+
+\set VERBOSITY terse
+SELECT xmlcanonicalize('', true);
+ERROR: invalid XML document
+SELECT xmlcanonicalize(' ', true);
+ERROR: invalid XML document
+SELECT xmlcanonicalize('foo', true);
+ERROR: invalid XML document
+SELECT xmlcanonicalize('');
+ERROR: invalid XML document
+SELECT xmlcanonicalize(' ');
+ERROR: invalid XML document
+SELECT xmlcanonicalize('foo');
+ERROR: invalid XML document
+\set VERBOSITY default
diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql
index 0ea4f50883..4af51a9908 100644
--- a/src/test/regress/sql/xml.sql
+++ b/src/test/regress/sql/xml.sql
@@ -679,3 +679,55 @@ SELECT xmltext(' ');
SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}');
SELECT xmltext('foo & <"bar">');
SELECT xmltext('x'|| '<P>73</P>'::xml || .42 || true || 'j'::char);
+
+-- xmlserialize: canonical
+CREATE TABLE xmlcanonicalize_test (doc xml);
+INSERT INTO xmlcanonicalize_test VALUES
+ ('<?xml version="1.0" encoding="ISO-8859-1"?>
+ <!DOCTYPE doc SYSTEM "doc.dtd" [
+ <!ENTITY val "42">
+ <!ATTLIST xyz attr CDATA "default">
+ ]>
+
+ <!-- attributes and namespces will be sorted -->
+ <foo a:attr="out" b:attr="sorted" attr2="all" attr="I am"
+ xmlns:b="http://www.ietf.org";
+ xmlns:a="http://www.w3.org";
+ xmlns="http://example.org";>
+
+ <!-- Normalization of whitespace in start and end tags -->
+ <!-- Elimination of superfluous namespace declarations, as already declared in <foo> -->
+ <bar xmlns="" xmlns:a="http://www.w3.org"; >&val;</bar >
+
+ <!-- empty element will be converted to start-end tag pair -->
+ <empty/>
+
+ <!-- text will be transcoded to UTF-8 -->
+ <transcode>1</transcode>
+
+ <!-- whitespace inside tag will be preserved -->
+ <whitespace> 321 </whitespace>
+
+ <!-- empty namespace will be removed of child tag -->
+ <emptyns xmlns="" >
+ <emptyns_child xmlns=""></emptyns_child>
+ </emptyns>
+
+ <!-- CDATA section will be replaced by its value -->
+ <compute><![CDATA[value>"0" && value<"10" ?"valid":"error"]]></compute>
+ </foo> <!-- comment outside root element --> ');
+
+SELECT xmlcanonicalize(doc, true) FROM xmlcanonicalize_test;
+SELECT xmlcanonicalize(doc, false) FROM xmlcanonicalize_test;
+SELECT xmlcanonicalize(doc, true)::text = xmlcanonicalize(doc)::text FROM xmlcanonicalize_test;
+SELECT xmlcanonicalize(doc, NULL) FROM xmlcanonicalize_test;
+SELECT xmlcanonicalize(NULL, true);
+
+\set VERBOSITY terse
+SELECT xmlcanonicalize('', true);
+SELECT xmlcanonicalize(' ', true);
+SELECT xmlcanonicalize('foo', true);
+SELECT xmlcanonicalize('');
+SELECT xmlcanonicalize(' ');
+SELECT xmlcanonicalize('foo');
+\set VERBOSITY default
\ No newline at end of file
--
2.43.0
