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peterepetere
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Fix namespace handling in xpath function
Previously, the xml value resulting from an xpath query would not have namespace declarations if the namespace declarations were attached to an ancestor element in the input xml value. That means the output value was not correct XML. Fix that by running the result value through xmlCopyNode(), which produces the correct namespace declarations. Author: Ali Akbar <the.apaan@gmail.com>
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+55
-8
lines changed

4 files changed

+55
-8
lines changed

‎src/backend/utils/adt/xml.c‎

Lines changed: 26 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -141,9 +141,10 @@ static bool print_xml_decl(StringInfo buf, const xmlChar *version,
141141
pg_enc encoding, int standalone);
142142
static xmlDocPtr xml_parse(text *data, XmlOptionType xmloption_arg,
143143
bool preserve_whitespace, int encoding);
144-
static text *xml_xmlnodetoxmltype(xmlNodePtr cur);
144+
static text *xml_xmlnodetoxmltype(xmlNodePtr cur, PgXmlErrorContext *xmlerrcxt);
145145
static int xml_xpathobjtoxmlarray(xmlXPathObjectPtr xpathobj,
146-
ArrayBuildState *astate);
146+
ArrayBuildState *astate,
147+
PgXmlErrorContext *xmlerrcxt);
147148
#endif /* USE_LIBXML */
148149

149150
static StringInfo query_to_xml_internal(const char *query, char *tablename,
@@ -3599,26 +3600,41 @@ SPI_sql_row_to_xmlelement(int rownum, StringInfo result, char *tablename,
35993600
* return value otherwise)
36003601
*/
36013602
static text *
3602-
xml_xmlnodetoxmltype(xmlNodePtr cur)
3603+
xml_xmlnodetoxmltype(xmlNodePtr cur, PgXmlErrorContext *xmlerrcxt)
36033604
{
36043605
xmltype *result;
36053606

36063607
if (cur->type == XML_ELEMENT_NODE)
36073608
{
36083609
xmlBufferPtr buf;
3610+
xmlNodePtr cur_copy;
36093611

36103612
buf = xmlBufferCreate();
3613+
3614+
/*
3615+
* The result of xmlNodeDump() won't contain namespace definitions
3616+
* from parent nodes, but xmlCopyNode() duplicates a node along with
3617+
* its required namespace definitions.
3618+
*/
3619+
cur_copy = xmlCopyNode(cur, 1);
3620+
3621+
if (cur_copy == NULL)
3622+
xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
3623+
"could not copy node");
3624+
36113625
PG_TRY();
36123626
{
3613-
xmlNodeDump(buf, NULL, cur, 0, 1);
3627+
xmlNodeDump(buf, NULL, cur_copy, 0, 1);
36143628
result = xmlBuffer_to_xmltype(buf);
36153629
}
36163630
PG_CATCH();
36173631
{
3632+
xmlFreeNode(cur_copy);
36183633
xmlBufferFree(buf);
36193634
PG_RE_THROW();
36203635
}
36213636
PG_END_TRY();
3637+
xmlFreeNode(cur_copy);
36223638
xmlBufferFree(buf);
36233639
}
36243640
else
@@ -3660,7 +3676,8 @@ xml_xmlnodetoxmltype(xmlNodePtr cur)
36603676
*/
36613677
static int
36623678
xml_xpathobjtoxmlarray(xmlXPathObjectPtr xpathobj,
3663-
ArrayBuildState *astate)
3679+
ArrayBuildState *astate,
3680+
PgXmlErrorContext *xmlerrcxt)
36643681
{
36653682
int result = 0;
36663683
Datum datum;
@@ -3679,7 +3696,8 @@ xml_xpathobjtoxmlarray(xmlXPathObjectPtr xpathobj,
36793696

36803697
for (i = 0; i < result; i++)
36813698
{
3682-
datum = PointerGetDatum(xml_xmlnodetoxmltype(xpathobj->nodesetval->nodeTab[i]));
3699+
datum = PointerGetDatum(xml_xmlnodetoxmltype(xpathobj->nodesetval->nodeTab[i],
3700+
xmlerrcxt));
36833701
(void) accumArrayResult(astate, datum, false,
36843702
XMLOID, CurrentMemoryContext);
36853703
}
@@ -3881,9 +3899,9 @@ xpath_internal(text *xpath_expr_text, xmltype *data, ArrayType *namespaces,
38813899
* Extract the results as requested.
38823900
*/
38833901
if (res_nitems != NULL)
3884-
*res_nitems = xml_xpathobjtoxmlarray(xpathobj, astate);
3902+
*res_nitems = xml_xpathobjtoxmlarray(xpathobj, astate, xmlerrcxt);
38853903
else
3886-
(void) xml_xpathobjtoxmlarray(xpathobj, astate);
3904+
(void) xml_xpathobjtoxmlarray(xpathobj, astate, xmlerrcxt);
38873905
}
38883906
PG_CATCH();
38893907
{

‎src/test/regress/expected/xml.out‎

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -612,6 +612,21 @@ SELECT xpath('//loc:piece/@id', '<local:data xmlns:local="http://127.0.0.1"><loc
612612
{1,2}
613613
(1 row)
614614

615+
SELECT xpath('//loc:piece', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>', ARRAY[ARRAY['loc', 'http://127.0.0.1']]);
616+
xpath
617+
------------------------------------------------------------------------------------------------------------------------------------------------
618+
{"<local:piece xmlns:local=\"http://127.0.0.1\" id=\"1\">number one</local:piece>","<local:piece xmlns:local=\"http://127.0.0.1\" id=\"2\"/>"}
619+
(1 row)
620+
621+
SELECT xpath('//loc:piece', '<local:data xmlns:local="http://127.0.0.1" xmlns="http://127.0.0.2"><local:piece id="1"><internal>number one</internal><internal2/></local:piece><local:piece id="2" /></local:data>', ARRAY[ARRAY['loc', 'http://127.0.0.1']]);
622+
xpath
623+
--------------------------------------------------------------------------------------
624+
{"<local:piece xmlns:local=\"http://127.0.0.1\" xmlns=\"http://127.0.0.2\" id=\"1\">+
625+
<internal>number one</internal> +
626+
<internal2/> +
627+
</local:piece>","<local:piece xmlns:local=\"http://127.0.0.1\" id=\"2\"/>"}
628+
(1 row)
629+
615630
SELECT xpath('//b', '<a>one <b>two</b> three <b>etc</b></a>');
616631
xpath
617632
-------------------------

‎src/test/regress/expected/xml_1.out‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -514,6 +514,18 @@ LINE 1: SELECT xpath('//loc:piece/@id', '<local:data xmlns:local="ht...
514514
^
515515
DETAIL: This functionality requires the server to be built with libxml support.
516516
HINT: You need to rebuild PostgreSQL using --with-libxml.
517+
SELECT xpath('//loc:piece', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>', ARRAY[ARRAY['loc', 'http://127.0.0.1']]);
518+
ERROR: unsupported XML feature
519+
LINE 1: SELECT xpath('//loc:piece', '<local:data xmlns:local="http:/...
520+
^
521+
DETAIL: This functionality requires the server to be built with libxml support.
522+
HINT: You need to rebuild PostgreSQL using --with-libxml.
523+
SELECT xpath('//loc:piece', '<local:data xmlns:local="http://127.0.0.1" xmlns="http://127.0.0.2"><local:piece id="1"><internal>number one</internal><internal2/></local:piece><local:piece id="2" /></local:data>', ARRAY[ARRAY['loc', 'http://127.0.0.1']]);
524+
ERROR: unsupported XML feature
525+
LINE 1: SELECT xpath('//loc:piece', '<local:data xmlns:local="http:/...
526+
^
527+
DETAIL: This functionality requires the server to be built with libxml support.
528+
HINT: You need to rebuild PostgreSQL using --with-libxml.
517529
SELECT xpath('//b', '<a>one <b>two</b> three <b>etc</b></a>');
518530
ERROR: unsupported XML feature
519531
LINE 1: SELECT xpath('//b', '<a>one <b>two</b> three <b>etc</b></a>'...

‎src/test/regress/sql/xml.sql‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -178,6 +178,8 @@ SELECT xpath(NULL, NULL) IS NULL FROM xmltest;
178178
SELECT xpath('', '<!-- error -->');
179179
SELECT xpath('//text()', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>');
180180
SELECT xpath('//loc:piece/@id', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>', ARRAY[ARRAY['loc', 'http://127.0.0.1']]);
181+
SELECT xpath('//loc:piece', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>', ARRAY[ARRAY['loc', 'http://127.0.0.1']]);
182+
SELECT xpath('//loc:piece', '<local:data xmlns:local="http://127.0.0.1" xmlns="http://127.0.0.2"><local:piece id="1"><internal>number one</internal><internal2/></local:piece><local:piece id="2" /></local:data>', ARRAY[ARRAY['loc', 'http://127.0.0.1']]);
181183
SELECT xpath('//b', '<a>one <b>two</b> three <b>etc</b></a>');
182184
SELECT xpath('//text()', '<root>&lt;</root>');
183185
SELECT xpath('//@value', '<root value="&lt;"/>');

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