@ -7,7 +7,7 @@
* Portions Copyright ( c ) 1996 - 2007 , PostgreSQL Global Development Group
* Portions Copyright ( c ) 1994 , Regents of the University of California
*
* $ PostgreSQL : pgsql / src / backend / utils / adt / xml . c , v 1.42 2007 / 04 / 06 04 : 21 : 43 tgl Exp $
* $ PostgreSQL : pgsql / src / backend / utils / adt / xml . c , v 1.43 2007 / 05 / 21 17 : 10 : 29 petere Exp $
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
@ -2991,90 +2991,94 @@ xml_xmlnodetoxmltype(xmlNodePtr cur)
}
# endif
/*
* Evaluate XPath expression and return array of XML values .
* As we have no support of XQuery sequences yet , this functions seems
* to be the most useful one ( array of XML functions plays a role of
* some kind of substritution for XQuery sequences ) .
*
* Workaround here : we parse XML data in different way to allow XPath for
* fragments ( see " XPath for fragment " TODO comment inside ) .
*/
Datum
xml path ( PG_FUNCTION_ARGS )
xpath ( PG_FUNCTION_ARGS )
{
# ifdef USE_LIBXML
ArrayBuildState * astate = NULL ;
text * xpath_expr_text = PG_GETARG_TEXT_P ( 0 ) ;
xmltype * data = PG_GETARG_XML_P ( 1 ) ;
ArrayType * namespaces = PG_GETARG_ARRAYTYPE_P ( 2 ) ;
ArrayBuildState * astate = NULL ;
xmlParserCtxtPtr ctxt = NULL ;
xmlDocPtr doc = NULL ;
xmlXPathContextPtr xpathctx = NULL ;
xmlXPathCompExprPtr xpathcomp = NULL ;
xmlXPathObjectPtr xpathobj = NULL ;
int32 len , xpath_len ;
xmlChar * string , * xpath_expr ;
bool res_is_null = FALSE ;
int i ;
xmltype * data ;
text * xpath_expr_text ;
ArrayType * namespaces ;
int * dims , ndims , ns_count = 0 , bitmask = 1 ;
char * ptr ;
bits8 * bitmap ;
char * * ns_names = NULL , * * ns_uris = NULL ;
int16 typlen ;
bool typbyval ;
char typalign ;
/* the function is not strict, we must check first two args */
if ( PG_ARGISNULL ( 0 ) | | PG_ARGISNULL ( 1 ) )
PG_RETURN_NULL ( ) ;
xpath_expr_text = PG_GETARG_TEXT_P ( 0 ) ;
data = PG_GETARG_XML_P ( 1 ) ;
/* Namespace mappings passed as text[].
* Assume that 2 - dimensional array has been passed ,
* the 1 st subarray is array of names , the 2 nd - - array of URIs ,
* example : ARRAY [ ARRAY [ ' myns ' , ' myns2 ' ] , ARRAY [ ' http : //example.com', 'http://example2.com']].
int32 len ;
int32 xpath_len ;
xmlChar * string ;
xmlChar * xpath_expr ;
int i ;
int res_nitems ;
int ndim ;
int ns_count ;
char * * ns_names ;
char * * ns_uris ;
/*
* Namespace mappings are passed as text [ ] . If an empty array is
* passed ( ndim = 0 , " 0-dimentional " ) , then there are no namespace
* mappings . Else , a 2 - dimentional array with length of the
* second axis being equal to 2 should be passed , i . e . , every
* subarray contains 2 elements , the first element defining the
* name , the second one the URI . Example : ARRAY [ ARRAY [ ' myns ' ,
* ' http : //example.com'], ARRAY['myns2', 'http://example2.com']].
*/
if ( ! PG_ARGISNULL ( 2 ) )
ndim = ARR_NDIM ( namespaces ) ;
if ( ndim ! = 0 )
{
namespaces = PG_GETARG_ARRAYTYPE_P ( 2 ) ;
ndims = ARR_NDIM ( namespaces ) ;
bits8 * bitmap ;
int bitmask ;
int16 typlen ;
bool typbyval ;
char typalign ;
char * ptr ;
int * dims ;
dims = ARR_DIMS ( namespaces ) ;
/* Sanity check */
if ( ndims ! = 2 )
ereport ( ERROR , ( errmsg ( " invalid array passed for namespace mappings " ) ,
errdetail ( " Only 2-dimensional array may be used for namespace mappings. " ) ) ) ;
if ( ndim ! = 2 | | dims [ 1 ] ! = 2 )
ereport ( ERROR , ( errmsg ( " invalid array for XML namespace mapping " ) ,
errdetail ( " The array must be two-dimensional with length of the second axis equal to 2. " ) ,
errcode ( ERRCODE_DATA_EXCEPTION ) ) ) ;
Assert ( ARR_ELEMTYPE ( namespaces ) = = TEXTOID ) ;
ns_count = ArrayGetNItems ( ndims , dims ) / 2 ;
ns_count = ArrayGetNItems ( ndim , dims ) / 2 ; /* number of NS mappings */
get_typlenbyvalalign ( ARR_ELEMTYPE ( namespaces ) ,
& typlen , & typbyval , & typalign ) ;
ns_names = ( char * * ) palloc ( ns_count * sizeof ( char * ) ) ;
ns_uris = ( char * * ) palloc ( ns_count * sizeof ( char * ) ) ;
ns_names = palloc ( ns_count * sizeof ( char * ) ) ;
ns_uris = palloc ( ns_count * sizeof ( char * ) ) ;
ptr = ARR_DATA_PTR ( namespaces ) ;
bitmap = ARR_NULLBITMAP ( namespaces ) ;
bitmask = 1 ;
for ( i = 0 ; i < ns_count * 2 ; i + + )
{
if ( bitmap & & ( * bitmap & bitmask ) = = 0 )
ereport ( ERROR , ( errmsg ( " neither namespace nor URI may be NULL " ) ) ) ; /* TODO: better message */
ereport ( ERROR , ( errmsg ( " neither namespace name nor URI may be null " ) ) ) ;
else
{
if ( i < ns_count )
ns_names [ i ] = DatumGetCString ( DirectFunctionCall1 ( textout ,
PointerGetDatum ( ptr ) ) ) ;
if ( i % 2 = = 0 )
ns_names [ i / 2 ] = DatumGetCString ( DirectFunctionCall1 ( textout ,
PointerGetDatum ( ptr ) ) ) ;
else
ns_uris [ i - ns_count ] = DatumGetCString ( DirectFunctionCall1 ( textout ,
PointerGetDatum ( ptr ) ) ) ;
ns_uris [ i / 2 ] = DatumGetCString ( DirectFunctionCall1 ( textout ,
PointerGetDatum ( ptr ) ) ) ;
ptr = att_addlength_pointer ( ptr , typlen , ptr ) ;
ptr = ( char * ) att_align_nominal ( ptr , typalign ) ;
}
/* advance bitmap pointer if any */
if ( bitmap )
{
@ -3087,37 +3091,55 @@ xmlpath(PG_FUNCTION_ARGS)
}
}
}
else
{
ns_count = 0 ;
ns_names = NULL ;
ns_uris = NULL ;
}
len = VARSIZE ( data ) - VARHDRSZ ;
xpath_len = VARSIZE ( xpath_expr_text ) - VARHDRSZ ;
if ( xpath_len = = 0 )
ereport ( ERROR , ( errmsg ( " empty XPath expression " ) ) ) ;
if ( xmlStrncmp ( ( xmlChar * ) VARDATA ( data ) , ( xmlChar * ) " <?xml " , 5 ) = = 0 )
ereport ( ERROR , ( errmsg ( " empty XPath expression " ) ,
errcode ( ERRCODE_DATA_EXCEPTION ) ) ) ;
/*
* To handle both documents and fragments , regardless of the fact
* whether the XML datum has a single root ( XML well - formedness ) ,
* we wrap the XML datum in a dummy element ( < x > . . . < / x > ) and
* extend the XPath expression accordingly . To do it , throw away
* the XML prolog , if any .
*/
if ( ( len > 4 ) & & xmlStrncmp ( ( xmlChar * ) VARDATA ( data ) , ( xmlChar * ) " <?xml " , 5 ) = = 0 )
{
string = palloc ( len + 1 ) ;
memcpy ( string , VARDATA ( data ) , len ) ;
string [ len ] = ' \0 ' ;
xpath_expr = palloc ( xpath_len + 1 ) ;
memcpy ( xpath_expr , VARDATA ( xpath_expr_text ) , xpath_len ) ;
xpath_expr [ xpath_len ] = ' \0 ' ;
i = 5 ;
while ( ( i < len ) & & ( ( ' ? ' ! = ( VARDATA ( data ) ) [ i - 1 ] ) | | ( ' > ' ! = ( VARDATA ( data ) ) [ i ] ) ) )
i + + ;
if ( i = = len )
xml_ereport ( ERROR , ERRCODE_INTERNAL_ERROR ,
" could not parse XML data " ) ;
+ + i ;
string = xmlStrncatNew ( ( xmlChar * ) " <x> " , ( xmlChar * ) VARDATA ( data ) + i , len - i ) ;
}
else
{
/* use "<x>...</x>" as dummy root element to enable XPath for fragments */
/* TODO: (XPath for fragment) find better solution to work with XML fragment! */
string = xmlStrncatNew ( ( xmlChar * ) " <x> " , ( xmlChar * ) VARDATA ( data ) , len ) ;
string = xmlStrncat ( string , ( xmlChar * ) " </x> " , 5 ) ;
len + = 7 ;
xpath_expr = xmlStrncatNew ( ( xmlChar * ) " /x " , ( xmlChar * ) VARDATA ( xpath_expr_text ) , xpath_len ) ;
len + = 2 ;
}
string = xmlStrncat ( string , ( xmlChar * ) " </x> " , 5 ) ;
len + = 7 ;
xpath_expr = xmlStrncatNew ( ( xmlChar * ) " /x " , ( xmlChar * ) VARDATA ( xpath_expr_text ) , xpath_len ) ;
xpath_len + = 2 ;
xml_init ( ) ;
PG_TRY ( ) ;
{
/* redundant XML parsing (two parsings for the same value in the same session are possible) */
/*
* redundant XML parsing ( two parsings for the same value *
* during one command execution are possible )
*/
ctxt = xmlNewParserCtxt ( ) ;
if ( ctxt = = NULL )
xml_ereport ( ERROR , ERRCODE_INTERNAL_ERROR ,
@ -3133,34 +3155,33 @@ xmlpath(PG_FUNCTION_ARGS)
xpathctx - > node = xmlDocGetRootElement ( doc ) ;
if ( xpathctx - > node = = NULL )
xml_ereport ( ERROR , ERRCODE_INTERNAL_ERROR ,
" could not find root XML element " ) ;
" could not find root XML element " ) ;
/* register namespaces, if any */
if ( ( ns_count > 0 ) & & ns_names & & ns_uris )
for ( i = 0 ; i < ns_count ; i + + )
if ( 0 ! = xmlXPathRegisterNs ( xpathctx , ( xmlChar * ) ns_names [ i ] , ( xmlChar * ) ns_uris [ i ] ) )
ereport ( ERROR ,
( errmsg ( " could not register XML namespace with prefix= \" %s \" and href= \" %s \" " , ns_names [ i ] , ns_uris [ i ] ) ) ) ;
ereport ( ERROR ,
( errmsg ( " could not register XML namespace with name \" %s \" and URI \" %s \" " ,
ns_names [ i ] , ns_uris [ i ] ) ) ) ;
xpathcomp = xmlXPathCompile ( xpath_expr ) ;
if ( xpathcomp = = NULL )
xml_ereport ( ERROR , ERRCODE_INTERNAL_ERROR ,
" invalid XPath expression " ) ; /* TODO: show proper XPath error details */
xpathobj = xmlXPathCompiledEval ( xpathcomp , xpathctx ) ;
xmlXPathFreeCompExpr ( xpathcomp ) ;
if ( xpathobj = = NULL )
ereport ( ERROR , ( errmsg ( " could not create XPath object " ) ) ) ;
ereport ( ERROR , ( errmsg ( " could not create XPath object " ) ) ) ; /* TODO: reason? */
/* return empty array in cases when nothing is found */
if ( xpathobj - > nodesetval = = NULL )
res_is_null = TRUE ;
if ( ! res_is_null & & xpathobj - > nodesetval - > nodeNr = = 0 )
/* TODO maybe empty array should be here, not NULL? (if so -- fix segfault) */
/*PG_RETURN_ARRAYTYPE_P(makeArrayResult(astate, CurrentMemoryContext));*/
res_is_null = TRUE ;
if ( ! res_is_null )
res_nitems = 0 ;
else
res_nitems = xpathobj - > nodesetval - > nodeNr ;
if ( res_nitems )
for ( i = 0 ; i < xpathobj - > nodesetval - > nodeNr ; i + + )
{
Datum elem ;
@ -3170,7 +3191,7 @@ xmlpath(PG_FUNCTION_ARGS)
elemisnull , XMLOID ,
CurrentMemoryContext ) ;
}
xmlXPathFreeObject ( xpathobj ) ;
xmlXPathFreeContext ( xpathctx ) ;
xmlFreeParserCtxt ( ctxt ) ;
@ -3194,15 +3215,11 @@ xmlpath(PG_FUNCTION_ARGS)
PG_RE_THROW ( ) ;
}
PG_END_TRY ( ) ;
if ( res_is_null )
{
PG_RETURN_NULL ( ) ;
}
if ( res_nitems = = 0 )
PG_RETURN_ARRAYTYPE_P ( construct_empty_array ( XMLOID ) ) ;
else
{
PG_RETURN_ARRAYTYPE_P ( makeArrayResult ( astate , CurrentMemoryContext ) ) ;
}
# else
NO_XML_SUPPORT ( ) ;
return 0 ;
Peter Eisentraut
19 years ago