Fix handling of namespace nodes in xpath() (xml)

xpath() attempted to call xmlCopyNode() and xmlNodeDump() on a
XML_NAMESPACE_DECL, finishing with a confusing error:
=# SELECT xpath('//namespace::foo', '<root xmlns:foo="http://127.0.0.1"/>');
ERROR:  53200: could not copy node
CONTEXT:  SQL function "xpath" statement 1

xpath() is changed so as it goes through xmlXPathCastNodeToString()
instead, that is able to handle namespace nodes.  xml2 uses the same
solution.  This issue has been discovered while digging into
9d33a5a804db.

Author: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/aioT7ui_ZJ9RMlfM@paquier.xyz
Backpatch-through: 14

diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index 3dd6cc037abed7582d399cc4f26ffbc6d715a171..b07f2d186d86aa9d152f1da33b14f305164488ec 100644 (file)
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -3854,7 +3854,9 @@ xml_xmlnodetoxmltype(xmlNodePtr cur, PgXmlErrorContext *xmlerrcxt)
 {
        xmltype    *result = NULL;
 
-       if (cur->type != XML_ATTRIBUTE_NODE && cur->type != XML_TEXT_NODE)
+       if (cur->type != XML_ATTRIBUTE_NODE &&
+               cur->type != XML_TEXT_NODE &&
+               cur->type != XML_NAMESPACE_DECL)
        {
                void            (*volatile nodefree) (xmlNodePtr) = NULL;
                volatile xmlBufferPtr buf = NULL;

diff --git a/src/test/regress/expected/xml.out b/src/test/regress/expected/xml.out
index 79054b753114b7acead32d6cc5fd3668f0e589eb..ec30cb76ce49ce09ee205f32830a79016afbb990 100644 (file)
--- a/src/test/regress/expected/xml.out
+++ b/src/test/regress/expected/xml.out
@@ -710,6 +710,12 @@ SELECT xpath('root', '<root/>');
  {<root/>}
 (1 row)
 
+SELECT xpath('//namespace::foo', '<root xmlns:foo="http://127.0.0.1"/>');
+       xpath        
+--------------------
+ {http://127.0.0.1}
+(1 row)
+
 -- Round-trip non-ASCII data through xpath().
 DO $$
 DECLARE

diff --git a/src/test/regress/expected/xml_1.out b/src/test/regress/expected/xml_1.out
index abf27626a215ed7f40cad7a73667e572d410f7b9..684fa070fe4157dbe690ebeecaf2a66f75cd1630 100644 (file)
--- a/src/test/regress/expected/xml_1.out
+++ b/src/test/regress/expected/xml_1.out
@@ -516,6 +516,11 @@ ERROR:  unsupported XML feature
 LINE 1: SELECT xpath('root', '<root/>');
                              ^
 DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xpath('//namespace::foo', '<root xmlns:foo="http://127.0.0.1"/>');
+ERROR:  unsupported XML feature
+LINE 1: SELECT xpath('//namespace::foo', '<root xmlns:foo="http://12...
+                                         ^
+DETAIL:  This functionality requires the server to be built with libxml support.
 -- Round-trip non-ASCII data through xpath().
 DO $$
 DECLARE

diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql
index 83c5b73d8d3e469ec983535a4b84ee6438cde3a8..57c3412d743b7911a567abe8666d950468c75e03 100644 (file)
--- a/src/test/regress/sql/xml.sql
+++ b/src/test/regress/sql/xml.sql
@@ -196,6 +196,7 @@ SELECT xpath('count(//*)=3', '<root><sub/><sub/></root>');
 SELECT xpath('name(/*)', '<root><sub/><sub/></root>');
 SELECT xpath('/nosuchtag', '<root/>');
 SELECT xpath('root', '<root/>');
+SELECT xpath('//namespace::foo', '<root xmlns:foo="http://127.0.0.1"/>');
 
 -- Round-trip non-ASCII data through xpath().
 DO $$