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postgres/src/backend/utils/adt/xml.c
Peter Eisentraut 641459f269 Add xmlexists function 
by Mike Fowler, reviewed by Peter Eisentraut
2010-08-05 04:21:54 +00:00

3544 lines
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/*-------------------------------------------------------------------------
*
* xml.c
* XML data type support.
*
*
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.99 2010/08/05 04:21:54 petere Exp $
*
*-------------------------------------------------------------------------
*/
/*
* Generally, XML type support is only available when libxml use was
* configured during the build. But even if that is not done, the
* type and all the functions are available, but most of them will
* fail. For one thing, this avoids having to manage variant catalog
* installations. But it also has nice effects such as that you can
* dump a database containing XML type data even if the server is not
* linked with libxml. Thus, make sure xml_out() works even if nothing
* else does.
*/
/*
* Notes on memory management:
*
* Sometimes libxml allocates global structures in the hope that it can reuse
* them later on. This makes it impractical to change the xmlMemSetup
* functions on-the-fly; that is likely to lead to trying to pfree() chunks
* allocated with malloc() or vice versa. Since libxml might be used by
* loadable modules, eg libperl, our only safe choices are to change the
* functions at postmaster/backend launch or not at all. Since we'd rather
* not activate libxml in sessions that might never use it, the latter choice
* is the preferred one. However, for debugging purposes it can be awfully
* handy to constrain libxml's allocations to be done in a specific palloc
* context, where they're easy to track. Therefore there is code here that
* can be enabled in debug builds to redirect libxml's allocations into a
* special context LibxmlContext. It's not recommended to turn this on in
* a production build because of the possibility of bad interactions with
* external modules.
*/
/* #define USE_LIBXMLCONTEXT */
#include "postgres.h"
#ifdef USE_LIBXML
#include <libxml/chvalid.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
#include <libxml/uri.h>
#include <libxml/xmlerror.h>
#include <libxml/xmlwriter.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#endif /* USE_LIBXML */
#include "catalog/namespace.h"
#include "catalog/pg_type.h"
#include "commands/dbcommands.h"
#include "executor/executor.h"
#include "executor/spi.h"
#include "fmgr.h"
#include "lib/stringinfo.h"
#include "libpq/pqformat.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "nodes/execnodes.h"
#include "nodes/nodeFuncs.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/datetime.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/syscache.h"
#include "utils/xml.h"
/* GUC variables */
int xmlbinary;
int xmloption;
#ifdef USE_LIBXML
static StringInfo xml_err_buf = NULL;
static void xml_errorHandler(void *ctxt, const char *msg,...);
static void xml_ereport_by_code(int level, int sqlcode,
const char *msg, int errcode);
#ifdef USE_LIBXMLCONTEXT
static MemoryContext LibxmlContext = NULL;
static void xml_memory_init(void);
static void *xml_palloc(size_t size);
static void *xml_repalloc(void *ptr, size_t size);
static void xml_pfree(void *ptr);
static char *xml_pstrdup(const char *string);
#endif /* USE_LIBXMLCONTEXT */
static xmlChar *xml_text2xmlChar(text *in);
static int parse_xml_decl(const xmlChar *str, size_t *lenp,
xmlChar **version, xmlChar **encoding, int *standalone);
static bool print_xml_decl(StringInfo buf, const xmlChar *version,
pg_enc encoding, int standalone);
static xmlDocPtr xml_parse(text *data, XmlOptionType xmloption_arg,
bool preserve_whitespace, int encoding);
static text *xml_xmlnodetoxmltype(xmlNodePtr cur);
#endif /* USE_LIBXML */
static StringInfo query_to_xml_internal(const char *query, char *tablename,
const char *xmlschema, bool nulls, bool tableforest,
const char *targetns, bool top_level);
static const char *map_sql_table_to_xmlschema(TupleDesc tupdesc, Oid relid,
bool nulls, bool tableforest, const char *targetns);
static const char *map_sql_schema_to_xmlschema_types(Oid nspid,
List *relid_list, bool nulls,
bool tableforest, const char *targetns);
static const char *map_sql_catalog_to_xmlschema_types(List *nspid_list,
bool nulls, bool tableforest,
const char *targetns);
static const char *map_sql_type_to_xml_name(Oid typeoid, int typmod);
static const char *map_sql_typecoll_to_xmlschema_types(List *tupdesc_list);
static const char *map_sql_type_to_xmlschema_type(Oid typeoid, int typmod);
static void SPI_sql_row_to_xmlelement(int rownum, StringInfo result,
char *tablename, bool nulls, bool tableforest,
const char *targetns, bool top_level);
#define NO_XML_SUPPORT() \
ereport(ERROR, \
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED), \
errmsg("unsupported XML feature"), \
errdetail("This functionality requires the server to be built with libxml support."), \
errhint("You need to rebuild PostgreSQL using --with-libxml.")))
/* from SQL/XML:2003 section 4.7 */
#define NAMESPACE_XSD "http://www.w3.org/2001/XMLSchema"
#define NAMESPACE_XSI "http://www.w3.org/2001/XMLSchema-instance"
#define NAMESPACE_SQLXML "http://standards.iso.org/iso/9075/2003/sqlxml"
#ifdef USE_LIBXML
static int
xmlChar_to_encoding(const xmlChar *encoding_name)
{
int encoding = pg_char_to_encoding((const char *) encoding_name);
if (encoding < 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid encoding name \"%s\"",
(const char *) encoding_name)));
return encoding;
}
#endif
/*
* xml_in uses a plain C string to VARDATA conversion, so for the time being
* we use the conversion function for the text datatype.
*
* This is only acceptable so long as xmltype and text use the same
* representation.
*/
Datum
xml_in(PG_FUNCTION_ARGS)
{
#ifdef USE_LIBXML
char *s = PG_GETARG_CSTRING(0);
xmltype *vardata;
xmlDocPtr doc;
vardata = (xmltype *) cstring_to_text(s);
/*
* Parse the data to check if it is well-formed XML data. Assume that
* ERROR occurred if parsing failed.
*/
doc = xml_parse(vardata, xmloption, true, GetDatabaseEncoding());
xmlFreeDoc(doc);
PG_RETURN_XML_P(vardata);
#else
NO_XML_SUPPORT();
return 0;
#endif
}
#define PG_XML_DEFAULT_VERSION "1.0"
/*
* xml_out_internal uses a plain VARDATA to C string conversion, so for the
* time being we use the conversion function for the text datatype.
*
* This is only acceptable so long as xmltype and text use the same
* representation.
*/
static char *
xml_out_internal(xmltype *x, pg_enc target_encoding)
{
char *str = text_to_cstring((text *) x);
#ifdef USE_LIBXML
size_t len = strlen(str);
xmlChar *version;
int standalone;
int res_code;
if ((res_code = parse_xml_decl((xmlChar *) str,
&len, &version, NULL, &standalone)) == 0)
{
StringInfoData buf;
initStringInfo(&buf);
if (!print_xml_decl(&buf, version, target_encoding, standalone))
{
/*
* If we are not going to produce an XML declaration, eat a single
* newline in the original string to prevent empty first lines in
* the output.
*/
if (*(str + len) == '\n')
len += 1;
}
appendStringInfoString(&buf, str + len);
pfree(str);
return buf.data;
}
xml_ereport_by_code(WARNING, ERRCODE_INTERNAL_ERROR,
"could not parse XML declaration in stored value",
res_code);
#endif
return str;
}
Datum
xml_out(PG_FUNCTION_ARGS)
{
xmltype *x = PG_GETARG_XML_P(0);
/*
* xml_out removes the encoding property in all cases. This is because we
* cannot control from here whether the datum will be converted to a
* different client encoding, so we'd do more harm than good by including
* it.
*/
PG_RETURN_CSTRING(xml_out_internal(x, 0));
}
Datum
xml_recv(PG_FUNCTION_ARGS)
{
#ifdef USE_LIBXML
StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
xmltype *result;
char *str;
char *newstr;
int nbytes;
xmlDocPtr doc;
xmlChar *encodingStr = NULL;
int encoding;
/*
* Read the data in raw format. We don't know yet what the encoding is, as
* that information is embedded in the xml declaration; so we have to
* parse that before converting to server encoding.
*/
nbytes = buf->len - buf->cursor;
str = (char *) pq_getmsgbytes(buf, nbytes);
/*
* We need a null-terminated string to pass to parse_xml_decl(). Rather
* than make a separate copy, make the temporary result one byte bigger
* than it needs to be.
*/
result = palloc(nbytes + 1 + VARHDRSZ);
SET_VARSIZE(result, nbytes + VARHDRSZ);
memcpy(VARDATA(result), str, nbytes);
str = VARDATA(result);
str[nbytes] = '\0';
parse_xml_decl((xmlChar *) str, NULL, NULL, &encodingStr, NULL);
/*
* If encoding wasn't explicitly specified in the XML header, treat it as
* UTF-8, as that's the default in XML. This is different from xml_in(),
* where the input has to go through the normal client to server encoding
* conversion.
*/
encoding = encodingStr ? xmlChar_to_encoding(encodingStr) : PG_UTF8;
/*
* Parse the data to check if it is well-formed XML data. Assume that
* xml_parse will throw ERROR if not.
*/
doc = xml_parse(result, xmloption, true, encoding);
xmlFreeDoc(doc);
/* Now that we know what we're dealing with, convert to server encoding */
newstr = (char *) pg_do_encoding_conversion((unsigned char *) str,
nbytes,
encoding,
GetDatabaseEncoding());
if (newstr != str)
{
pfree(result);
result = (xmltype *) cstring_to_text(newstr);
pfree(newstr);
}
PG_RETURN_XML_P(result);
#else
NO_XML_SUPPORT();
return 0;
#endif
}
Datum
xml_send(PG_FUNCTION_ARGS)
{
xmltype *x = PG_GETARG_XML_P(0);
char *outval;
StringInfoData buf;
/*
* xml_out_internal doesn't convert the encoding, it just prints the right
* declaration. pq_sendtext will do the conversion.
*/
outval = xml_out_internal(x, pg_get_client_encoding());
pq_begintypsend(&buf);
pq_sendtext(&buf, outval, strlen(outval));
pfree(outval);
PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
#ifdef USE_LIBXML
static void
appendStringInfoText(StringInfo str, const text *t)
{
appendBinaryStringInfo(str, VARDATA(t), VARSIZE(t) - VARHDRSZ);
}
#endif
static xmltype *
stringinfo_to_xmltype(StringInfo buf)
{
return (xmltype *) cstring_to_text_with_len(buf->data, buf->len);
}
static xmltype *
cstring_to_xmltype(const char *string)
{
return (xmltype *) cstring_to_text(string);
}
#ifdef USE_LIBXML
static xmltype *
xmlBuffer_to_xmltype(xmlBufferPtr buf)
{
return (xmltype *) cstring_to_text_with_len((char *) xmlBufferContent(buf),
xmlBufferLength(buf));
}
#endif
Datum
xmlcomment(PG_FUNCTION_ARGS)
{
#ifdef USE_LIBXML
text *arg = PG_GETARG_TEXT_P(0);
char *argdata = VARDATA(arg);
int len = VARSIZE(arg) - VARHDRSZ;
StringInfoData buf;
int i;
/* check for "--" in string or "-" at the end */
for (i = 1; i < len; i++)
{
if (argdata[i] == '-' && argdata[i - 1] == '-')
ereport(ERROR,
(errcode(ERRCODE_INVALID_XML_COMMENT),
errmsg("invalid XML comment")));
}
if (len > 0 && argdata[len - 1] == '-')
ereport(ERROR,
(errcode(ERRCODE_INVALID_XML_COMMENT),
errmsg("invalid XML comment")));
initStringInfo(&buf);
appendStringInfo(&buf, "<!--");
appendStringInfoText(&buf, arg);
appendStringInfo(&buf, "-->");
PG_RETURN_XML_P(stringinfo_to_xmltype(&buf));
#else
NO_XML_SUPPORT();
return 0;
#endif
}
/*
* TODO: xmlconcat needs to merge the notations and unparsed entities
* of the argument values. Not very important in practice, though.
*/
xmltype *
xmlconcat(List *args)
{
#ifdef USE_LIBXML
int global_standalone = 1;
xmlChar *global_version = NULL;
bool global_version_no_value = false;
StringInfoData buf;
ListCell *v;
initStringInfo(&buf);
foreach(v, args)
{
xmltype *x = DatumGetXmlP(PointerGetDatum(lfirst(v)));
size_t len;
xmlChar *version;
int standalone;
char *str;
len = VARSIZE(x) - VARHDRSZ;
str = text_to_cstring((text *) x);
parse_xml_decl((xmlChar *) str, &len, &version, NULL, &standalone);
if (standalone == 0 && global_standalone == 1)
global_standalone = 0;
if (standalone < 0)
global_standalone = -1;
if (!version)
global_version_no_value = true;
else if (!global_version)
global_version = version;
else if (xmlStrcmp(version, global_version) != 0)
global_version_no_value = true;
appendStringInfoString(&buf, str + len);
pfree(str);
}
if (!global_version_no_value || global_standalone >= 0)
{
StringInfoData buf2;
initStringInfo(&buf2);
print_xml_decl(&buf2,
(!global_version_no_value) ? global_version : NULL,
0,
global_standalone);
appendStringInfoString(&buf2, buf.data);
buf = buf2;
}
return stringinfo_to_xmltype(&buf);
#else
NO_XML_SUPPORT();
return NULL;
#endif
}
/*
* XMLAGG support
*/
Datum
xmlconcat2(PG_FUNCTION_ARGS)
{
if (PG_ARGISNULL(0))
{
if (PG_ARGISNULL(1))
PG_RETURN_NULL();
else
PG_RETURN_XML_P(PG_GETARG_XML_P(1));
}
else if (PG_ARGISNULL(1))
PG_RETURN_XML_P(PG_GETARG_XML_P(0));
else
PG_RETURN_XML_P(xmlconcat(list_make2(PG_GETARG_XML_P(0),
PG_GETARG_XML_P(1))));
}
Datum
texttoxml(PG_FUNCTION_ARGS)
{
text *data = PG_GETARG_TEXT_P(0);
PG_RETURN_XML_P(xmlparse(data, xmloption, true));
}
Datum
xmltotext(PG_FUNCTION_ARGS)
{
xmltype *data = PG_GETARG_XML_P(0);
/* It's actually binary compatible. */
PG_RETURN_TEXT_P((text *) data);
}
text *
xmltotext_with_xmloption(xmltype *data, XmlOptionType xmloption_arg)
{
if (xmloption_arg == XMLOPTION_DOCUMENT && !xml_is_document(data))
ereport(ERROR,
(errcode(ERRCODE_NOT_AN_XML_DOCUMENT),
errmsg("not an XML document")));
/* It's actually binary compatible, save for the above check. */
return (text *) data;
}
xmltype *
xmlelement(XmlExprState *xmlExpr, ExprContext *econtext)
{
#ifdef USE_LIBXML
XmlExpr *xexpr = (XmlExpr *) xmlExpr->xprstate.expr;
xmltype *result;
List *named_arg_strings;
List *arg_strings;
int i;
ListCell *arg;
ListCell *narg;
xmlBufferPtr buf = NULL;
xmlTextWriterPtr writer = NULL;
/*
* We first evaluate all the arguments, then start up libxml and create
* the result. This avoids issues if one of the arguments involves a call
* to some other function or subsystem that wants to use libxml on its own
* terms.
*/
named_arg_strings = NIL;
i = 0;
foreach(arg, xmlExpr->named_args)
{
ExprState *e = (ExprState *) lfirst(arg);
Datum value;
bool isnull;
char *str;
value = ExecEvalExpr(e, econtext, &isnull, NULL);
if (isnull)
str = NULL;
else
str = map_sql_value_to_xml_value(value, exprType((Node *) e->expr), false);
named_arg_strings = lappend(named_arg_strings, str);
i++;
}
arg_strings = NIL;
foreach(arg, xmlExpr->args)
{
ExprState *e = (ExprState *) lfirst(arg);
Datum value;
bool isnull;
char *str;
value = ExecEvalExpr(e, econtext, &isnull, NULL);
/* here we can just forget NULL elements immediately */
if (!isnull)
{
str = map_sql_value_to_xml_value(value,
exprType((Node *) e->expr), true);
arg_strings = lappend(arg_strings, str);
}
}
/* now safe to run libxml */
pg_xml_init();
PG_TRY();
{
buf = xmlBufferCreate();
if (!buf)
xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate xmlBuffer");
writer = xmlNewTextWriterMemory(buf, 0);
if (!writer)
xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate xmlTextWriter");
xmlTextWriterStartElement(writer, (xmlChar *) xexpr->name);
forboth(arg, named_arg_strings, narg, xexpr->arg_names)
{
char *str = (char *) lfirst(arg);
char *argname = strVal(lfirst(narg));
if (str)
xmlTextWriterWriteAttribute(writer,
(xmlChar *) argname,
(xmlChar *) str);
}
foreach(arg, arg_strings)
{
char *str = (char *) lfirst(arg);
xmlTextWriterWriteRaw(writer, (xmlChar *) str);
}
xmlTextWriterEndElement(writer);
/* we MUST do this now to flush data out to the buffer ... */
xmlFreeTextWriter(writer);
writer = NULL;
result = xmlBuffer_to_xmltype(buf);
}
PG_CATCH();
{
if (writer)
xmlFreeTextWriter(writer);
if (buf)
xmlBufferFree(buf);
PG_RE_THROW();
}
PG_END_TRY();
xmlBufferFree(buf);
return result;
#else
NO_XML_SUPPORT();
return NULL;
#endif
}
xmltype *
xmlparse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace)
{
#ifdef USE_LIBXML
xmlDocPtr doc;
doc = xml_parse(data, xmloption_arg, preserve_whitespace,
GetDatabaseEncoding());
xmlFreeDoc(doc);
return (xmltype *) data;
#else
NO_XML_SUPPORT();
return NULL;
#endif
}
xmltype *
xmlpi(char *target, text *arg, bool arg_is_null, bool *result_is_null)
{
#ifdef USE_LIBXML
xmltype *result;
StringInfoData buf;
if (pg_strcasecmp(target, "xml") == 0)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR), /* really */
errmsg("invalid XML processing instruction"),
errdetail("XML processing instruction target name cannot be \"%s\".", target)));
/*
* Following the SQL standard, the null check comes after the syntax check
* above.
*/
*result_is_null = arg_is_null;
if (*result_is_null)
return NULL;
initStringInfo(&buf);
appendStringInfo(&buf, "<?%s", target);
if (arg != NULL)
{
char *string;
string = text_to_cstring(arg);
if (strstr(string, "?>") != NULL)
ereport(ERROR,
(errcode(ERRCODE_INVALID_XML_PROCESSING_INSTRUCTION),
errmsg("invalid XML processing instruction"),
errdetail("XML processing instruction cannot contain \"?>\".")));
appendStringInfoChar(&buf, ' ');
appendStringInfoString(&buf, string + strspn(string, " "));
pfree(string);
}
appendStringInfoString(&buf, "?>");
result = stringinfo_to_xmltype(&buf);
pfree(buf.data);
return result;
#else
NO_XML_SUPPORT();
return NULL;
#endif
}
xmltype *
xmlroot(xmltype *data, text *version, int standalone)
{
#ifdef USE_LIBXML
char *str;
size_t len;
xmlChar *orig_version;
int orig_standalone;
StringInfoData buf;
len = VARSIZE(data) - VARHDRSZ;
str = text_to_cstring((text *) data);
parse_xml_decl((xmlChar *) str, &len, &orig_version, NULL, &orig_standalone);
if (version)
orig_version = xml_text2xmlChar(version);
else
orig_version = NULL;
switch (standalone)
{
case XML_STANDALONE_YES:
orig_standalone = 1;
break;
case XML_STANDALONE_NO:
orig_standalone = 0;
break;
case XML_STANDALONE_NO_VALUE:
orig_standalone = -1;
break;
case XML_STANDALONE_OMITTED:
/* leave original value */
break;
}
initStringInfo(&buf);
print_xml_decl(&buf, orig_version, 0, orig_standalone);
appendStringInfoString(&buf, str + len);
return stringinfo_to_xmltype(&buf);
#else
NO_XML_SUPPORT();
return NULL;
#endif
}
/*
* Validate document (given as string) against DTD (given as external link)
*
* This has been removed because it is a security hole: unprivileged users
* should not be able to use Postgres to fetch arbitrary external files,
* which unfortunately is exactly what libxml is willing to do with the DTD
* parameter.
*/
Datum
xmlvalidate(PG_FUNCTION_ARGS)
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("xmlvalidate is not implemented")));
return 0;
}
bool
xml_is_document(xmltype *arg)
{
#ifdef USE_LIBXML
bool result;
xmlDocPtr doc = NULL;
MemoryContext ccxt = CurrentMemoryContext;
/* We want to catch ereport(INVALID_XML_DOCUMENT) and return false */
PG_TRY();
{
doc = xml_parse((text *) arg, XMLOPTION_DOCUMENT, true,
GetDatabaseEncoding());
result = true;
}
PG_CATCH();
{
ErrorData *errdata;
MemoryContext ecxt;
ecxt = MemoryContextSwitchTo(ccxt);
errdata = CopyErrorData();
if (errdata->sqlerrcode == ERRCODE_INVALID_XML_DOCUMENT)
{
FlushErrorState();
result = false;
}
else
{
MemoryContextSwitchTo(ecxt);
PG_RE_THROW();
}
}
PG_END_TRY();
if (doc)
xmlFreeDoc(doc);
return result;
#else /* not USE_LIBXML */
NO_XML_SUPPORT();
return false;
#endif /* not USE_LIBXML */
}
#ifdef USE_LIBXML
/*
* pg_xml_init --- set up for use of libxml
*
* This should be called by each function that is about to use libxml
* facilities. It has two responsibilities: verify compatibility with the
* loaded libxml version (done on first call in a session) and establish
* or re-establish our libxml error handler. The latter needs to be done
* anytime we might have passed control to add-on modules (eg libperl) which
* might have set their own error handler for libxml.
*
* This is exported for use by contrib/xml2, as well as other code that might
* wish to share use of this module's libxml error handler.
*
* TODO: xmlChar is utf8-char, make proper tuning (initdb with enc!=utf8 and
* check)
*/
void
pg_xml_init(void)
{
static bool first_time = true;
if (first_time)
{
/* Stuff we need do only once per session */
MemoryContext oldcontext;
/*
* Currently, we have no pure UTF-8 support for internals -- check if
* we can work.
*/
if (sizeof(char) != sizeof(xmlChar))
ereport(ERROR,
(errmsg("could not initialize XML library"),
errdetail("libxml2 has incompatible char type: sizeof(char)=%u, sizeof(xmlChar)=%u.",
(int) sizeof(char), (int) sizeof(xmlChar))));
/* create error buffer in permanent context */
oldcontext = MemoryContextSwitchTo(TopMemoryContext);
xml_err_buf = makeStringInfo();
MemoryContextSwitchTo(oldcontext);
/* Now that xml_err_buf exists, safe to call xml_errorHandler */
xmlSetGenericErrorFunc(NULL, xml_errorHandler);
#ifdef USE_LIBXMLCONTEXT
/* Set up memory allocation our way, too */
xml_memory_init();
#endif
/* Check library compatibility */
LIBXML_TEST_VERSION;
first_time = false;
}
else
{
/* Reset pre-existing buffer to empty */
Assert(xml_err_buf != NULL);
resetStringInfo(xml_err_buf);
/*
* We re-establish the error callback function every time. This makes
* it safe for other subsystems (PL/Perl, say) to also use libxml with
* their own callbacks ... so long as they likewise set up the
* callbacks on every use. It's cheap enough to not be worth worrying
* about, anyway.
*/
xmlSetGenericErrorFunc(NULL, xml_errorHandler);
}
}
/*
* SQL/XML allows storing "XML documents" or "XML content". "XML
* documents" are specified by the XML specification and are parsed
* easily by libxml. "XML content" is specified by SQL/XML as the
* production "XMLDecl? content". But libxml can only parse the
* "content" part, so we have to parse the XML declaration ourselves
* to complete this.
*/
#define CHECK_XML_SPACE(p) \
do { \
if (!xmlIsBlank_ch(*(p))) \
return XML_ERR_SPACE_REQUIRED; \
} while (0)
#define SKIP_XML_SPACE(p) \
while (xmlIsBlank_ch(*(p))) (p)++
/* Letter | Digit | '.' | '-' | '_' | ':' | CombiningChar | Extender */
/* Beware of multiple evaluations of argument! */
#define PG_XMLISNAMECHAR(c) \
(xmlIsBaseChar_ch(c) || xmlIsIdeographicQ(c) \
|| xmlIsDigit_ch(c) \
|| c == '.' || c == '-' || c == '_' || c == ':' \
|| xmlIsCombiningQ(c) \
|| xmlIsExtender_ch(c))
/* pnstrdup, but deal with xmlChar not char; len is measured in xmlChars */
static xmlChar *
xml_pnstrdup(const xmlChar *str, size_t len)
{
xmlChar *result;
result = (xmlChar *) palloc((len + 1) * sizeof(xmlChar));
memcpy(result, str, len * sizeof(xmlChar));
result[len] = 0;
return result;
}
/*
* str is the null-terminated input string. Remaining arguments are
* output arguments; each can be NULL if value is not wanted.
* version and encoding are returned as locally-palloc'd strings.
* Result is 0 if OK, an error code if not.
*/
static int
parse_xml_decl(const xmlChar *str, size_t *lenp,
xmlChar **version, xmlChar **encoding, int *standalone)
{
const xmlChar *p;
const xmlChar *save_p;
size_t len;
int utf8char;
int utf8len;
pg_xml_init();
/* Initialize output arguments to "not present" */
if (version)
*version = NULL;
if (encoding)
*encoding = NULL;
if (standalone)
*standalone = -1;
p = str;
if (xmlStrncmp(p, (xmlChar *) "<?xml", 5) != 0)
goto finished;
/* if next char is name char, it's a PI like <?xml-stylesheet ...?> */
utf8len = strlen((const char *) (p + 5));
utf8char = xmlGetUTF8Char(p + 5, &utf8len);
if (PG_XMLISNAMECHAR(utf8char))
goto finished;
p += 5;
/* version */
CHECK_XML_SPACE(p);
SKIP_XML_SPACE(p);
if (xmlStrncmp(p, (xmlChar *) "version", 7) != 0)
return XML_ERR_VERSION_MISSING;
p += 7;
SKIP_XML_SPACE(p);
if (*p != '=')
return XML_ERR_VERSION_MISSING;
p += 1;
SKIP_XML_SPACE(p);
if (*p == '\'' || *p == '"')
{
const xmlChar *q;
q = xmlStrchr(p + 1, *p);
if (!q)
return XML_ERR_VERSION_MISSING;
if (version)
*version = xml_pnstrdup(p + 1, q - p - 1);
p = q + 1;
}
else
return XML_ERR_VERSION_MISSING;
/* encoding */
save_p = p;
SKIP_XML_SPACE(p);
if (xmlStrncmp(p, (xmlChar *) "encoding", 8) == 0)
{
CHECK_XML_SPACE(save_p);
p += 8;
SKIP_XML_SPACE(p);
if (*p != '=')
return XML_ERR_MISSING_ENCODING;
p += 1;
SKIP_XML_SPACE(p);
if (*p == '\'' || *p == '"')
{
const xmlChar *q;
q = xmlStrchr(p + 1, *p);
if (!q)
return XML_ERR_MISSING_ENCODING;
if (encoding)
*encoding = xml_pnstrdup(p + 1, q - p - 1);
p = q + 1;
}
else
return XML_ERR_MISSING_ENCODING;
}
else
{
p = save_p;
}
/* standalone */
save_p = p;
SKIP_XML_SPACE(p);
if (xmlStrncmp(p, (xmlChar *) "standalone", 10) == 0)
{
CHECK_XML_SPACE(save_p);
p += 10;
SKIP_XML_SPACE(p);
if (*p != '=')
return XML_ERR_STANDALONE_VALUE;
p += 1;
SKIP_XML_SPACE(p);
if (xmlStrncmp(p, (xmlChar *) "'yes'", 5) == 0 ||
xmlStrncmp(p, (xmlChar *) "\"yes\"", 5) == 0)
{
*standalone = 1;
p += 5;
}
else if (xmlStrncmp(p, (xmlChar *) "'no'", 4) == 0 ||
xmlStrncmp(p, (xmlChar *) "\"no\"", 4) == 0)
{
*standalone = 0;
p += 4;
}
else
return XML_ERR_STANDALONE_VALUE;
}
else
{
p = save_p;
}
SKIP_XML_SPACE(p);
if (xmlStrncmp(p, (xmlChar *) "?>", 2) != 0)
return XML_ERR_XMLDECL_NOT_FINISHED;
p += 2;
finished:
len = p - str;
for (p = str; p < str + len; p++)
if (*p > 127)
return XML_ERR_INVALID_CHAR;
if (lenp)
*lenp = len;
return XML_ERR_OK;
}
/*
* Write an XML declaration. On output, we adjust the XML declaration
* as follows. (These rules are the moral equivalent of the clause
* "Serialization of an XML value" in the SQL standard.)
*
* We try to avoid generating an XML declaration if possible. This is
* so that you don't get trivial things like xml '<foo/>' resulting in
* '<?xml version="1.0"?><foo/>', which would surely be annoying. We
* must provide a declaration if the standalone property is specified
* or if we include an encoding declaration. If we have a
* declaration, we must specify a version (XML requires this).
* Otherwise we only make a declaration if the version is not "1.0",
* which is the default version specified in SQL:2003.
*/
static bool
print_xml_decl(StringInfo buf, const xmlChar *version,
pg_enc encoding, int standalone)
{
pg_xml_init(); /* why is this here? */
if ((version && strcmp((char *) version, PG_XML_DEFAULT_VERSION) != 0)
|| (encoding && encoding != PG_UTF8)
|| standalone != -1)
{
appendStringInfoString(buf, "<?xml");
if (version)
appendStringInfo(buf, " version=\"%s\"", version);
else
appendStringInfo(buf, " version=\"%s\"", PG_XML_DEFAULT_VERSION);
if (encoding && encoding != PG_UTF8)
{
/*
* XXX might be useful to convert this to IANA names (ISO-8859-1
* instead of LATIN1 etc.); needs field experience
*/
appendStringInfo(buf, " encoding=\"%s\"",
pg_encoding_to_char(encoding));
}
if (standalone == 1)
appendStringInfoString(buf, " standalone=\"yes\"");
else if (standalone == 0)
appendStringInfoString(buf, " standalone=\"no\"");
appendStringInfoString(buf, "?>");
return true;
}
else
return false;
}
/*
* Convert a C string to XML internal representation
*
* Note: it is caller's responsibility to xmlFreeDoc() the result,
* else a permanent memory leak will ensue!
*
* TODO maybe libxml2's xmlreader is better? (do not construct DOM,
* yet do not use SAX - see xmlreader.c)
*/
static xmlDocPtr
xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
int encoding)
{
int32 len;
xmlChar *string;
xmlChar *utf8string;
xmlParserCtxtPtr ctxt;
xmlDocPtr doc;
len = VARSIZE(data) - VARHDRSZ; /* will be useful later */
string = xml_text2xmlChar(data);
utf8string = pg_do_encoding_conversion(string,
len,
encoding,
PG_UTF8);
/* Start up libxml and its parser (no-ops if already done) */
pg_xml_init();
xmlInitParser();
ctxt = xmlNewParserCtxt();
if (ctxt == NULL)
xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate parser context");
/* Use a TRY block to ensure the ctxt is released */
PG_TRY();
{
if (xmloption_arg == XMLOPTION_DOCUMENT)
{
/*
* Note, that here we try to apply DTD defaults
* (XML_PARSE_DTDATTR) according to SQL/XML:10.16.7.d: 'Default
* values defined by internal DTD are applied'. As for external
* DTDs, we try to support them too, (see SQL/XML:10.16.7.e)
*/
doc = xmlCtxtReadDoc(ctxt, utf8string,
NULL,
"UTF-8",
XML_PARSE_NOENT | XML_PARSE_DTDATTR
| (preserve_whitespace ? 0 : XML_PARSE_NOBLANKS));
if (doc == NULL)
xml_ereport(ERROR, ERRCODE_INVALID_XML_DOCUMENT,
"invalid XML document");
}
else
{
int res_code;
size_t count;
xmlChar *version = NULL;
int standalone = -1;
res_code = parse_xml_decl(utf8string,
&count, &version, NULL, &standalone);
if (res_code != 0)
xml_ereport_by_code(ERROR, ERRCODE_INVALID_XML_CONTENT,
"invalid XML content: invalid XML declaration",
res_code);
doc = xmlNewDoc(version);
Assert(doc->encoding == NULL);
doc->encoding = xmlStrdup((const xmlChar *) "UTF-8");
doc->standalone = standalone;
res_code = xmlParseBalancedChunkMemory(doc, NULL, NULL, 0,
utf8string + count, NULL);
if (res_code != 0)
{
xmlFreeDoc(doc);
xml_ereport(ERROR, ERRCODE_INVALID_XML_CONTENT,
"invalid XML content");
}
}
}
PG_CATCH();
{
xmlFreeParserCtxt(ctxt);
PG_RE_THROW();
}
PG_END_TRY();
xmlFreeParserCtxt(ctxt);
return doc;
}
/*
* xmlChar<->text conversions
*/
static xmlChar *
xml_text2xmlChar(text *in)
{
return (xmlChar *) text_to_cstring(in);
}
#ifdef USE_LIBXMLCONTEXT
/*
* Manage the special context used for all libxml allocations (but only
* in special debug builds; see notes at top of file)
*/
static void
xml_memory_init(void)
{
/* Create memory context if not there already */
if (LibxmlContext == NULL)
LibxmlContext = AllocSetContextCreate(TopMemoryContext,
"LibxmlContext",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/* Re-establish the callbacks even if already set */
xmlMemSetup(xml_pfree, xml_palloc, xml_repalloc, xml_pstrdup);
}
/*
* Wrappers for memory management functions
*/
static void *
xml_palloc(size_t size)
{
return MemoryContextAlloc(LibxmlContext, size);
}
static void *
xml_repalloc(void *ptr, size_t size)
{
return repalloc(ptr, size);
}
static void
xml_pfree(void *ptr)
{
/* At least some parts of libxml assume xmlFree(NULL) is allowed */
if (ptr)
pfree(ptr);
}
static char *
xml_pstrdup(const char *string)
{
return MemoryContextStrdup(LibxmlContext, string);
}
#endif /* USE_LIBXMLCONTEXT */
/*
* xml_ereport --- report an XML-related error
*
* The "msg" is the SQL-level message; some can be adopted from the SQL/XML
* standard. This function adds libxml's native error message, if any, as
* detail.
*
* This is exported for modules that want to share the core libxml error
* handler. Note that pg_xml_init() *must* have been called previously.
*/
void
xml_ereport(int level, int sqlcode, const char *msg)
{
char *detail;
/*
* It might seem that we should just pass xml_err_buf->data directly to
* errdetail. However, we want to clean out xml_err_buf before throwing
* error, in case there is another function using libxml further down the
* call stack.
*/
if (xml_err_buf->len > 0)
{
detail = pstrdup(xml_err_buf->data);
resetStringInfo(xml_err_buf);
}
else
detail = NULL;
if (detail)
{
size_t len;
/* libxml error messages end in '\n'; get rid of it */
len = strlen(detail);
if (len > 0 && detail[len - 1] == '\n')
detail[len - 1] = '\0';
ereport(level,
(errcode(sqlcode),
errmsg("%s", msg),
errdetail("%s", detail)));
}
else
{
ereport(level,
(errcode(sqlcode),
errmsg("%s", msg)));
}
}
/*
* Error handler for libxml error messages
*/
static void
xml_errorHandler(void *ctxt, const char *msg,...)
{
/* Append the formatted text to xml_err_buf */
for (;;)
{
va_list args;
bool success;
/* Try to format the data. */
va_start(args, msg);
success = appendStringInfoVA(xml_err_buf, msg, args);
va_end(args);
if (success)
break;
/* Double the buffer size and try again. */
enlargeStringInfo(xml_err_buf, xml_err_buf->maxlen);
}
}
/*
* Wrapper for "ereport" function for XML-related errors. The "msg"
* is the SQL-level message; some can be adopted from the SQL/XML
* standard. This function uses "code" to create a textual detail
* message. At the moment, we only need to cover those codes that we
* may raise in this file.
*/
static void
xml_ereport_by_code(int level, int sqlcode,
const char *msg, int code)
{
const char *det;
switch (code)
{
case XML_ERR_INVALID_CHAR:
det = gettext_noop("Invalid character value.");
break;
case XML_ERR_SPACE_REQUIRED:
det = gettext_noop("Space required.");
break;
case XML_ERR_STANDALONE_VALUE:
det = gettext_noop("standalone accepts only 'yes' or 'no'.");
break;
case XML_ERR_VERSION_MISSING:
det = gettext_noop("Malformed declaration: missing version.");
break;
case XML_ERR_MISSING_ENCODING:
det = gettext_noop("Missing encoding in text declaration.");
break;
case XML_ERR_XMLDECL_NOT_FINISHED:
det = gettext_noop("Parsing XML declaration: '?>' expected.");
break;
default:
det = gettext_noop("Unrecognized libxml error code: %d.");
break;
}
ereport(level,
(errcode(sqlcode),
errmsg("%s", msg),
errdetail(det, code)));
}
/*
* Convert one char in the current server encoding to a Unicode codepoint.
*/
static pg_wchar
sqlchar_to_unicode(char *s)
{
char *utf8string;
pg_wchar ret[2]; /* need space for trailing zero */
utf8string = (char *) pg_do_encoding_conversion((unsigned char *) s,
pg_mblen(s),
GetDatabaseEncoding(),
PG_UTF8);
pg_encoding_mb2wchar_with_len(PG_UTF8, utf8string, ret,
pg_encoding_mblen(PG_UTF8, utf8string));
if (utf8string != s)
pfree(utf8string);
return ret[0];
}
static bool
is_valid_xml_namefirst(pg_wchar c)
{
/* (Letter | '_' | ':') */
return (xmlIsBaseCharQ(c) || xmlIsIdeographicQ(c)
|| c == '_' || c == ':');
}
static bool
is_valid_xml_namechar(pg_wchar c)
{
/* Letter | Digit | '.' | '-' | '_' | ':' | CombiningChar | Extender */
return (xmlIsBaseCharQ(c) || xmlIsIdeographicQ(c)
|| xmlIsDigitQ(c)
|| c == '.' || c == '-' || c == '_' || c == ':'
|| xmlIsCombiningQ(c)
|| xmlIsExtenderQ(c));
}
#endif /* USE_LIBXML */
/*
* Map SQL identifier to XML name; see SQL/XML:2003 section 9.1.
*/
char *
map_sql_identifier_to_xml_name(char *ident, bool fully_escaped,
bool escape_period)
{
#ifdef USE_LIBXML
StringInfoData buf;
char *p;
/*
* SQL/XML doesn't make use of this case anywhere, so it's probably a
* mistake.
*/
Assert(fully_escaped || !escape_period);
initStringInfo(&buf);
for (p = ident; *p; p += pg_mblen(p))
{
if (*p == ':' && (p == ident || fully_escaped))
appendStringInfo(&buf, "_x003A_");
else if (*p == '_' && *(p + 1) == 'x')
appendStringInfo(&buf, "_x005F_");
else if (fully_escaped && p == ident &&
pg_strncasecmp(p, "xml", 3) == 0)
{
if (*p == 'x')
appendStringInfo(&buf, "_x0078_");
else
appendStringInfo(&buf, "_x0058_");
}
else if (escape_period && *p == '.')
appendStringInfo(&buf, "_x002E_");
else
{
pg_wchar u = sqlchar_to_unicode(p);
if ((p == ident)
? !is_valid_xml_namefirst(u)
: !is_valid_xml_namechar(u))
appendStringInfo(&buf, "_x%04X_", (unsigned int) u);
else
appendBinaryStringInfo(&buf, p, pg_mblen(p));
}
}
return buf.data;
#else /* not USE_LIBXML */
NO_XML_SUPPORT();
return NULL;
#endif /* not USE_LIBXML */
}
/*
* Map a Unicode codepoint into the current server encoding.
*/
static char *
unicode_to_sqlchar(pg_wchar c)
{
unsigned char utf8string[5]; /* need room for trailing zero */
char *result;
memset(utf8string, 0, sizeof(utf8string));
unicode_to_utf8(c, utf8string);
result = (char *) pg_do_encoding_conversion(utf8string,
pg_encoding_mblen(PG_UTF8,
(char *) utf8string),
PG_UTF8,
GetDatabaseEncoding());
/* if pg_do_encoding_conversion didn't strdup, we must */
if (result == (char *) utf8string)
result = pstrdup(result);
return result;
}
/*
* Map XML name to SQL identifier; see SQL/XML:2003 section 9.17.
*/
char *
map_xml_name_to_sql_identifier(char *name)
{
StringInfoData buf;
char *p;
initStringInfo(&buf);
for (p = name; *p; p += pg_mblen(p))
{
if (*p == '_' && *(p + 1) == 'x'
&& isxdigit((unsigned char) *(p + 2))
&& isxdigit((unsigned char) *(p + 3))
&& isxdigit((unsigned char) *(p + 4))
&& isxdigit((unsigned char) *(p + 5))
&& *(p + 6) == '_')
{
unsigned int u;
sscanf(p + 2, "%X", &u);
appendStringInfoString(&buf, unicode_to_sqlchar(u));
p += 6;
}
else
appendBinaryStringInfo(&buf, p, pg_mblen(p));
}
return buf.data;
}
/*
* Map SQL value to XML value; see SQL/XML:2003 section 9.16.
*
* When xml_escape_strings is true, then certain characters in string
* values are replaced by entity references (&lt; etc.), as specified
* in SQL/XML:2003 section 9.16 GR 8) ii). This is normally what is
* wanted. The false case is mainly useful when the resulting value
* is used with xmlTextWriterWriteAttribute() to write out an
* attribute, because that function does the escaping itself. The SQL
* standard of 2003 is somewhat buggy in this regard, so we do our
* best to make sense.
*/
char *
map_sql_value_to_xml_value(Datum value, Oid type, bool xml_escape_strings)
{
if (type_is_array(type))
{
ArrayType *array;
Oid elmtype;
int16 elmlen;
bool elmbyval;
char elmalign;
int num_elems;
Datum *elem_values;
bool *elem_nulls;
StringInfoData buf;
int i;
array = DatumGetArrayTypeP(value);
elmtype = ARR_ELEMTYPE(array);
get_typlenbyvalalign(elmtype, &elmlen, &elmbyval, &elmalign);
deconstruct_array(array, elmtype,
elmlen, elmbyval, elmalign,
&elem_values, &elem_nulls,
&num_elems);
initStringInfo(&buf);
for (i = 0; i < num_elems; i++)
{
if (elem_nulls[i])
continue;
appendStringInfoString(&buf, "<element>");
appendStringInfoString(&buf,
map_sql_value_to_xml_value(elem_values[i],
elmtype, true));
appendStringInfoString(&buf, "</element>");
}
pfree(elem_values);
pfree(elem_nulls);
return buf.data;
}
else
{
Oid typeOut;
bool isvarlena;
char *str;
/*
* Special XSD formatting for some data types
*/
switch (type)
{
case BOOLOID:
if (DatumGetBool(value))
return "true";
else
return "false";
case DATEOID:
{
DateADT date;
struct pg_tm tm;
char buf[MAXDATELEN + 1];
date = DatumGetDateADT(value);
/* XSD doesn't support infinite values */
if (DATE_NOT_FINITE(date))
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("date out of range"),
errdetail("XML does not support infinite date values.")));
j2date(date + POSTGRES_EPOCH_JDATE,
&(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
EncodeDateOnly(&tm, USE_XSD_DATES, buf);
return pstrdup(buf);
}
case TIMESTAMPOID:
{
Timestamp timestamp;
struct pg_tm tm;
fsec_t fsec;
char *tzn = NULL;
char buf[MAXDATELEN + 1];
timestamp = DatumGetTimestamp(value);
/* XSD doesn't support infinite values */
if (TIMESTAMP_NOT_FINITE(timestamp))
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("timestamp out of range"),
errdetail("XML does not support infinite timestamp values.")));
else if (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, NULL) == 0)
EncodeDateTime(&tm, fsec, NULL, &tzn, USE_XSD_DATES, buf);
else
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("timestamp out of range")));
return pstrdup(buf);
}
case TIMESTAMPTZOID:
{
TimestampTz timestamp;
struct pg_tm tm;
int tz;
fsec_t fsec;
char *tzn = NULL;
char buf[MAXDATELEN + 1];
timestamp = DatumGetTimestamp(value);
/* XSD doesn't support infinite values */
if (TIMESTAMP_NOT_FINITE(timestamp))
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("timestamp out of range"),
errdetail("XML does not support infinite timestamp values.")));
else if (timestamp2tm(timestamp, &tz, &tm, &fsec, &tzn, NULL) == 0)
EncodeDateTime(&tm, fsec, &tz, &tzn, USE_XSD_DATES, buf);
else
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("timestamp out of range")));
return pstrdup(buf);
}
#ifdef USE_LIBXML
case BYTEAOID:
{
bytea *bstr = DatumGetByteaPP(value);
xmlBufferPtr buf = NULL;
xmlTextWriterPtr writer = NULL;
char *result;
pg_xml_init();
PG_TRY();
{
buf = xmlBufferCreate();
if (!buf)
xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate xmlBuffer");
writer = xmlNewTextWriterMemory(buf, 0);
if (!writer)
xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate xmlTextWriter");
if (xmlbinary == XMLBINARY_BASE64)
xmlTextWriterWriteBase64(writer, VARDATA_ANY(bstr),
0, VARSIZE_ANY_EXHDR(bstr));
else
xmlTextWriterWriteBinHex(writer, VARDATA_ANY(bstr),
0, VARSIZE_ANY_EXHDR(bstr));
/* we MUST do this now to flush data out to the buffer */
xmlFreeTextWriter(writer);
writer = NULL;
result = pstrdup((const char *) xmlBufferContent(buf));
}
PG_CATCH();
{
if (writer)
xmlFreeTextWriter(writer);
if (buf)
xmlBufferFree(buf);
PG_RE_THROW();
}
PG_END_TRY();
xmlBufferFree(buf);
return result;
}
#endif /* USE_LIBXML */
}
/*
* otherwise, just use the type's native text representation
*/
getTypeOutputInfo(type, &typeOut, &isvarlena);
str = OidOutputFunctionCall(typeOut, value);
/* ... exactly as-is for XML, and when escaping is not wanted */
if (type == XMLOID || !xml_escape_strings)
return str;
/* otherwise, translate special characters as needed */
return escape_xml(str);
}
}
/*
* Escape characters in text that have special meanings in XML.
*
* Returns a palloc'd string.
*
* NB: this is intentionally not dependent on libxml.
*/
char *
escape_xml(const char *str)
{
StringInfoData buf;
const char *p;
initStringInfo(&buf);
for (p = str; *p; p++)
{
switch (*p)
{
case '&':
appendStringInfoString(&buf, "&amp;");
break;
case '<':
appendStringInfoString(&buf, "&lt;");
break;
case '>':
appendStringInfoString(&buf, "&gt;");
break;
case '\r':
appendStringInfoString(&buf, "&#x0d;");
break;
default:
appendStringInfoCharMacro(&buf, *p);
break;
}
}
return buf.data;
}
static char *
_SPI_strdup(const char *s)
{
size_t len = strlen(s) + 1;
char *ret = SPI_palloc(len);
memcpy(ret, s, len);
return ret;
}
/*
* SQL to XML mapping functions
*
* What follows below is intentionally organized so that you can read
* along in the SQL/XML:2003 standard. The functions are mostly split
* up and ordered they way the clauses lay out in the standards
* document, and the identifiers are also aligned with the standard
* text. (SQL/XML:2006 appears to be ordered differently,
* unfortunately.)
*
* There are many things going on there:
*
* There are two kinds of mappings: Mapping SQL data (table contents)
* to XML documents, and mapping SQL structure (the "schema") to XML
* Schema. And there are functions that do both at the same time.
*
* Then you can map a database, a schema, or a table, each in both
* ways. This breaks down recursively: Mapping a database invokes
* mapping schemas, which invokes mapping tables, which invokes
* mapping rows, which invokes mapping columns, although you can't
* call the last two from the outside. Because of this, there are a
* number of xyz_internal() functions which are to be called both from
* the function manager wrapper and from some upper layer in a
* recursive call.
*
* See the documentation about what the common function arguments
* nulls, tableforest, and targetns mean.
*
* Some style guidelines for XML output: Use double quotes for quoting
* XML attributes. Indent XML elements by two spaces, but remember
* that a lot of code is called recursively at different levels, so
* it's better not to indent rather than create output that indents
* and outdents weirdly. Add newlines to make the output look nice.
*/
/*
* Visibility of objects for XML mappings; see SQL/XML:2003 section
* 4.8.5.
*/
/*
* Given a query, which must return type oid as first column, produce
* a list of Oids with the query results.
*/
static List *
query_to_oid_list(const char *query)
{
int i;
List *list = NIL;
SPI_execute(query, true, 0);
for (i = 0; i < SPI_processed; i++)
{
Datum oid;
bool isnull;
oid = SPI_getbinval(SPI_tuptable->vals[i],
SPI_tuptable->tupdesc,
1,
&isnull);
if (!isnull)
list = lappend_oid(list, DatumGetObjectId(oid));
}
return list;
}
static List *
schema_get_xml_visible_tables(Oid nspid)
{
StringInfoData query;
initStringInfo(&query);
appendStringInfo(&query, "SELECT oid FROM pg_catalog.pg_class WHERE relnamespace = %u AND relkind IN ('r', 'v') AND pg_catalog.has_table_privilege (oid, 'SELECT') ORDER BY relname;", nspid);
return query_to_oid_list(query.data);
}
/*
* Including the system schemas is probably not useful for a database
* mapping.
*/
#define XML_VISIBLE_SCHEMAS_EXCLUDE "(nspname ~ '^pg_' OR nspname = 'information_schema')"
#define XML_VISIBLE_SCHEMAS "SELECT oid FROM pg_catalog.pg_namespace WHERE pg_catalog.has_schema_privilege (oid, 'USAGE') AND NOT " XML_VISIBLE_SCHEMAS_EXCLUDE
static List *
database_get_xml_visible_schemas(void)
{
return query_to_oid_list(XML_VISIBLE_SCHEMAS " ORDER BY nspname;");
}
static List *
database_get_xml_visible_tables(void)
{
/* At the moment there is no order required here. */
return query_to_oid_list("SELECT oid FROM pg_catalog.pg_class WHERE relkind IN ('r', 'v') AND pg_catalog.has_table_privilege (pg_class.oid, 'SELECT') AND relnamespace IN (" XML_VISIBLE_SCHEMAS ");");
}
/*
* Map SQL table to XML and/or XML Schema document; see SQL/XML:2003
* section 9.3.
*/
static StringInfo
table_to_xml_internal(Oid relid,
const char *xmlschema, bool nulls, bool tableforest,
const char *targetns, bool top_level)
{
StringInfoData query;
initStringInfo(&query);
appendStringInfo(&query, "SELECT * FROM %s",
DatumGetCString(DirectFunctionCall1(regclassout,
ObjectIdGetDatum(relid))));
return query_to_xml_internal(query.data, get_rel_name(relid),
xmlschema, nulls, tableforest,
targetns, top_level);
}
Datum
table_to_xml(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
bool nulls = PG_GETARG_BOOL(1);
bool tableforest = PG_GETARG_BOOL(2);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
PG_RETURN_XML_P(stringinfo_to_xmltype(table_to_xml_internal(relid, NULL,
nulls, tableforest,
targetns, true)));
}
Datum
query_to_xml(PG_FUNCTION_ARGS)
{
char *query = text_to_cstring(PG_GETARG_TEXT_PP(0));
bool nulls = PG_GETARG_BOOL(1);
bool tableforest = PG_GETARG_BOOL(2);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
PG_RETURN_XML_P(stringinfo_to_xmltype(query_to_xml_internal(query, NULL,
NULL, nulls, tableforest,
targetns, true)));
}
Datum
cursor_to_xml(PG_FUNCTION_ARGS)
{
char *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
int32 count = PG_GETARG_INT32(1);
bool nulls = PG_GETARG_BOOL(2);
bool tableforest = PG_GETARG_BOOL(3);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(4));
StringInfoData result;
Portal portal;
int i;
initStringInfo(&result);
SPI_connect();
portal = SPI_cursor_find(name);
if (portal == NULL)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_CURSOR),
errmsg("cursor \"%s\" does not exist", name)));
SPI_cursor_fetch(portal, true, count);
for (i = 0; i < SPI_processed; i++)
SPI_sql_row_to_xmlelement(i, &result, NULL, nulls,
tableforest, targetns, true);
SPI_finish();
PG_RETURN_XML_P(stringinfo_to_xmltype(&result));
}
/*
* Write the start tag of the root element of a data mapping.
*
* top_level means that this is the very top level of the eventual
* output. For example, when the user calls table_to_xml, then a call
* with a table name to this function is the top level. When the user
* calls database_to_xml, then a call with a schema name to this
* function is not the top level. If top_level is false, then the XML
* namespace declarations are omitted, because they supposedly already
* appeared earlier in the output. Repeating them is not wrong, but
* it looks ugly.
*/
static void
xmldata_root_element_start(StringInfo result, const char *eltname,
const char *xmlschema, const char *targetns,
bool top_level)
{
/* This isn't really wrong but currently makes no sense. */
Assert(top_level || !xmlschema);
appendStringInfo(result, "<%s", eltname);
if (top_level)
{
appendStringInfoString(result, " xmlns:xsi=\"" NAMESPACE_XSI "\"");
if (strlen(targetns) > 0)
appendStringInfo(result, " xmlns=\"%s\"", targetns);
}
if (xmlschema)
{
/* FIXME: better targets */
if (strlen(targetns) > 0)
appendStringInfo(result, " xsi:schemaLocation=\"%s #\"", targetns);
else
appendStringInfo(result, " xsi:noNamespaceSchemaLocation=\"#\"");
}
appendStringInfo(result, ">\n\n");
}
static void
xmldata_root_element_end(StringInfo result, const char *eltname)
{
appendStringInfo(result, "</%s>\n", eltname);
}
static StringInfo
query_to_xml_internal(const char *query, char *tablename,
const char *xmlschema, bool nulls, bool tableforest,
const char *targetns, bool top_level)
{
StringInfo result;
char *xmltn;
int i;
if (tablename)
xmltn = map_sql_identifier_to_xml_name(tablename, true, false);
else
xmltn = "table";
result = makeStringInfo();
SPI_connect();
if (SPI_execute(query, true, 0) != SPI_OK_SELECT)
ereport(ERROR,
(errcode(ERRCODE_DATA_EXCEPTION),
errmsg("invalid query")));
if (!tableforest)
xmldata_root_element_start(result, xmltn, xmlschema,
targetns, top_level);
if (xmlschema)
appendStringInfo(result, "%s\n\n", xmlschema);
for (i = 0; i < SPI_processed; i++)
SPI_sql_row_to_xmlelement(i, result, tablename, nulls,
tableforest, targetns, top_level);
if (!tableforest)
xmldata_root_element_end(result, xmltn);
SPI_finish();
return result;
}
Datum
table_to_xmlschema(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
bool nulls = PG_GETARG_BOOL(1);
bool tableforest = PG_GETARG_BOOL(2);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
const char *result;
Relation rel;
rel = heap_open(relid, AccessShareLock);
result = map_sql_table_to_xmlschema(rel->rd_att, relid, nulls,
tableforest, targetns);
heap_close(rel, NoLock);
PG_RETURN_XML_P(cstring_to_xmltype(result));
}
Datum
query_to_xmlschema(PG_FUNCTION_ARGS)
{
char *query = text_to_cstring(PG_GETARG_TEXT_PP(0));
bool nulls = PG_GETARG_BOOL(1);
bool tableforest = PG_GETARG_BOOL(2);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
const char *result;
SPIPlanPtr plan;
Portal portal;
SPI_connect();
if ((plan = SPI_prepare(query, 0, NULL)) == NULL)
elog(ERROR, "SPI_prepare(\"%s\") failed", query);
if ((portal = SPI_cursor_open(NULL, plan, NULL, NULL, true)) == NULL)
elog(ERROR, "SPI_cursor_open(\"%s\") failed", query);
result = _SPI_strdup(map_sql_table_to_xmlschema(portal->tupDesc,
InvalidOid, nulls,
tableforest, targetns));
SPI_cursor_close(portal);
SPI_finish();
PG_RETURN_XML_P(cstring_to_xmltype(result));
}
Datum
cursor_to_xmlschema(PG_FUNCTION_ARGS)
{
char *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
bool nulls = PG_GETARG_BOOL(1);
bool tableforest = PG_GETARG_BOOL(2);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
const char *xmlschema;
Portal portal;
SPI_connect();
portal = SPI_cursor_find(name);
if (portal == NULL)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_CURSOR),
errmsg("cursor \"%s\" does not exist", name)));
xmlschema = _SPI_strdup(map_sql_table_to_xmlschema(portal->tupDesc,
InvalidOid, nulls,
tableforest, targetns));
SPI_finish();
PG_RETURN_XML_P(cstring_to_xmltype(xmlschema));
}
Datum
table_to_xml_and_xmlschema(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
bool nulls = PG_GETARG_BOOL(1);
bool tableforest = PG_GETARG_BOOL(2);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
Relation rel;
const char *xmlschema;
rel = heap_open(relid, AccessShareLock);
xmlschema = map_sql_table_to_xmlschema(rel->rd_att, relid, nulls,
tableforest, targetns);
heap_close(rel, NoLock);
PG_RETURN_XML_P(stringinfo_to_xmltype(table_to_xml_internal(relid,
xmlschema, nulls, tableforest,
targetns, true)));
}
Datum
query_to_xml_and_xmlschema(PG_FUNCTION_ARGS)
{
char *query = text_to_cstring(PG_GETARG_TEXT_PP(0));
bool nulls = PG_GETARG_BOOL(1);
bool tableforest = PG_GETARG_BOOL(2);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
const char *xmlschema;
SPIPlanPtr plan;
Portal portal;
SPI_connect();
if ((plan = SPI_prepare(query, 0, NULL)) == NULL)
elog(ERROR, "SPI_prepare(\"%s\") failed", query);
if ((portal = SPI_cursor_open(NULL, plan, NULL, NULL, true)) == NULL)
elog(ERROR, "SPI_cursor_open(\"%s\") failed", query);
xmlschema = _SPI_strdup(map_sql_table_to_xmlschema(portal->tupDesc,
InvalidOid, nulls, tableforest, targetns));
SPI_cursor_close(portal);
SPI_finish();
PG_RETURN_XML_P(stringinfo_to_xmltype(query_to_xml_internal(query, NULL,
xmlschema, nulls, tableforest,
targetns, true)));
}
/*
* Map SQL schema to XML and/or XML Schema document; see SQL/XML:2003
* section 9.4.
*/
static StringInfo
schema_to_xml_internal(Oid nspid, const char *xmlschema, bool nulls,
bool tableforest, const char *targetns, bool top_level)
{
StringInfo result;
char *xmlsn;
List *relid_list;
ListCell *cell;
xmlsn = map_sql_identifier_to_xml_name(get_namespace_name(nspid),
true, false);
result = makeStringInfo();
xmldata_root_element_start(result, xmlsn, xmlschema, targetns, top_level);
if (xmlschema)
appendStringInfo(result, "%s\n\n", xmlschema);
SPI_connect();
relid_list = schema_get_xml_visible_tables(nspid);
SPI_push();
foreach(cell, relid_list)
{
Oid relid = lfirst_oid(cell);
StringInfo subres;
subres = table_to_xml_internal(relid, NULL, nulls, tableforest,
targetns, false);
appendStringInfoString(result, subres->data);
appendStringInfoChar(result, '\n');
}
SPI_pop();
SPI_finish();
xmldata_root_element_end(result, xmlsn);
return result;
}
Datum
schema_to_xml(PG_FUNCTION_ARGS)
{
Name name = PG_GETARG_NAME(0);
bool nulls = PG_GETARG_BOOL(1);
bool tableforest = PG_GETARG_BOOL(2);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
char *schemaname;
Oid nspid;
schemaname = NameStr(*name);
nspid = LookupExplicitNamespace(schemaname);
PG_RETURN_XML_P(stringinfo_to_xmltype(schema_to_xml_internal(nspid, NULL,
nulls, tableforest, targetns, true)));
}
/*
* Write the start element of the root element of an XML Schema mapping.
*/
static void
xsd_schema_element_start(StringInfo result, const char *targetns)
{
appendStringInfoString(result,
"<xsd:schema\n"
" xmlns:xsd=\"" NAMESPACE_XSD "\"");
if (strlen(targetns) > 0)
appendStringInfo(result,
"\n"
" targetNamespace=\"%s\"\n"
" elementFormDefault=\"qualified\"",
targetns);
appendStringInfoString(result,
">\n\n");
}
static void
xsd_schema_element_end(StringInfo result)
{
appendStringInfoString(result, "</xsd:schema>");
}
static StringInfo
schema_to_xmlschema_internal(const char *schemaname, bool nulls,
bool tableforest, const char *targetns)
{
Oid nspid;
List *relid_list;
List *tupdesc_list;
ListCell *cell;
StringInfo result;
result = makeStringInfo();
nspid = LookupExplicitNamespace(schemaname);
xsd_schema_element_start(result, targetns);
SPI_connect();
relid_list = schema_get_xml_visible_tables(nspid);
tupdesc_list = NIL;
foreach(cell, relid_list)
{
Relation rel;
rel = heap_open(lfirst_oid(cell), AccessShareLock);
tupdesc_list = lappend(tupdesc_list, CreateTupleDescCopy(rel->rd_att));
heap_close(rel, NoLock);
}
appendStringInfoString(result,
map_sql_typecoll_to_xmlschema_types(tupdesc_list));
appendStringInfoString(result,
map_sql_schema_to_xmlschema_types(nspid, relid_list,
nulls, tableforest, targetns));
xsd_schema_element_end(result);
SPI_finish();
return result;
}
Datum
schema_to_xmlschema(PG_FUNCTION_ARGS)
{
Name name = PG_GETARG_NAME(0);
bool nulls = PG_GETARG_BOOL(1);
bool tableforest = PG_GETARG_BOOL(2);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
PG_RETURN_XML_P(stringinfo_to_xmltype(schema_to_xmlschema_internal(NameStr(*name),
nulls, tableforest, targetns)));
}
Datum
schema_to_xml_and_xmlschema(PG_FUNCTION_ARGS)
{
Name name = PG_GETARG_NAME(0);
bool nulls = PG_GETARG_BOOL(1);
bool tableforest = PG_GETARG_BOOL(2);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(3));
char *schemaname;
Oid nspid;
StringInfo xmlschema;
schemaname = NameStr(*name);
nspid = LookupExplicitNamespace(schemaname);
xmlschema = schema_to_xmlschema_internal(schemaname, nulls,
tableforest, targetns);
PG_RETURN_XML_P(stringinfo_to_xmltype(schema_to_xml_internal(nspid,
xmlschema->data, nulls,
tableforest, targetns, true)));
}
/*
* Map SQL database to XML and/or XML Schema document; see SQL/XML:2003
* section 9.5.
*/
static StringInfo
database_to_xml_internal(const char *xmlschema, bool nulls,
bool tableforest, const char *targetns)
{
StringInfo result;
List *nspid_list;
ListCell *cell;
char *xmlcn;
xmlcn = map_sql_identifier_to_xml_name(get_database_name(MyDatabaseId),
true, false);
result = makeStringInfo();
xmldata_root_element_start(result, xmlcn, xmlschema, targetns, true);
if (xmlschema)
appendStringInfo(result, "%s\n\n", xmlschema);
SPI_connect();
nspid_list = database_get_xml_visible_schemas();
SPI_push();
foreach(cell, nspid_list)
{
Oid nspid = lfirst_oid(cell);
StringInfo subres;
subres = schema_to_xml_internal(nspid, NULL, nulls,
tableforest, targetns, false);
appendStringInfoString(result, subres->data);
appendStringInfoChar(result, '\n');
}
SPI_pop();
SPI_finish();
xmldata_root_element_end(result, xmlcn);
return result;
}
Datum
database_to_xml(PG_FUNCTION_ARGS)
{
bool nulls = PG_GETARG_BOOL(0);
bool tableforest = PG_GETARG_BOOL(1);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(2));
PG_RETURN_XML_P(stringinfo_to_xmltype(database_to_xml_internal(NULL, nulls,
tableforest, targetns)));
}
static StringInfo
database_to_xmlschema_internal(bool nulls, bool tableforest,
const char *targetns)
{
List *relid_list;
List *nspid_list;
List *tupdesc_list;
ListCell *cell;
StringInfo result;
result = makeStringInfo();
xsd_schema_element_start(result, targetns);
SPI_connect();
relid_list = database_get_xml_visible_tables();
nspid_list = database_get_xml_visible_schemas();
tupdesc_list = NIL;
foreach(cell, relid_list)
{
Relation rel;
rel = heap_open(lfirst_oid(cell), AccessShareLock);
tupdesc_list = lappend(tupdesc_list, CreateTupleDescCopy(rel->rd_att));
heap_close(rel, NoLock);
}
appendStringInfoString(result,
map_sql_typecoll_to_xmlschema_types(tupdesc_list));
appendStringInfoString(result,
map_sql_catalog_to_xmlschema_types(nspid_list, nulls, tableforest, targetns));
xsd_schema_element_end(result);
SPI_finish();
return result;
}
Datum
database_to_xmlschema(PG_FUNCTION_ARGS)
{
bool nulls = PG_GETARG_BOOL(0);
bool tableforest = PG_GETARG_BOOL(1);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(2));
PG_RETURN_XML_P(stringinfo_to_xmltype(database_to_xmlschema_internal(nulls,
tableforest, targetns)));
}
Datum
database_to_xml_and_xmlschema(PG_FUNCTION_ARGS)
{
bool nulls = PG_GETARG_BOOL(0);
bool tableforest = PG_GETARG_BOOL(1);
const char *targetns = text_to_cstring(PG_GETARG_TEXT_PP(2));
StringInfo xmlschema;
xmlschema = database_to_xmlschema_internal(nulls, tableforest, targetns);
PG_RETURN_XML_P(stringinfo_to_xmltype(database_to_xml_internal(xmlschema->data,
nulls, tableforest, targetns)));
}
/*
* Map a multi-part SQL name to an XML name; see SQL/XML:2003 section
* 9.2.
*/
static char *
map_multipart_sql_identifier_to_xml_name(char *a, char *b, char *c, char *d)
{
StringInfoData result;
initStringInfo(&result);
if (a)
appendStringInfo(&result, "%s",
map_sql_identifier_to_xml_name(a, true, true));
if (b)
appendStringInfo(&result, ".%s",
map_sql_identifier_to_xml_name(b, true, true));
if (c)
appendStringInfo(&result, ".%s",
map_sql_identifier_to_xml_name(c, true, true));
if (d)
appendStringInfo(&result, ".%s",
map_sql_identifier_to_xml_name(d, true, true));
return result.data;
}
/*
* Map an SQL table to an XML Schema document; see SQL/XML:2003
* section 9.3.
*
* Map an SQL table to XML Schema data types; see SQL/XML:2003 section
* 9.6.
*/
static const char *
map_sql_table_to_xmlschema(TupleDesc tupdesc, Oid relid, bool nulls,
bool tableforest, const char *targetns)
{
int i;
char *xmltn;
char *tabletypename;
char *rowtypename;
StringInfoData result;
initStringInfo(&result);
if (OidIsValid(relid))
{
HeapTuple tuple;
Form_pg_class reltuple;
tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for relation %u", relid);
reltuple = (Form_pg_class) GETSTRUCT(tuple);
xmltn = map_sql_identifier_to_xml_name(NameStr(reltuple->relname),
true, false);
tabletypename = map_multipart_sql_identifier_to_xml_name("TableType",
get_database_name(MyDatabaseId),
get_namespace_name(reltuple->relnamespace),
NameStr(reltuple->relname));
rowtypename = map_multipart_sql_identifier_to_xml_name("RowType",
get_database_name(MyDatabaseId),
get_namespace_name(reltuple->relnamespace),
NameStr(reltuple->relname));
ReleaseSysCache(tuple);
}
else
{
if (tableforest)
xmltn = "row";
else
xmltn = "table";
tabletypename = "TableType";
rowtypename = "RowType";
}
xsd_schema_element_start(&result, targetns);
appendStringInfoString(&result,
map_sql_typecoll_to_xmlschema_types(list_make1(tupdesc)));
appendStringInfo(&result,
"<xsd:complexType name=\"%s\">\n"
" <xsd:sequence>\n",
rowtypename);
for (i = 0; i < tupdesc->natts; i++)
{
if (tupdesc->attrs[i]->attisdropped)
continue;
appendStringInfo(&result,
" <xsd:element name=\"%s\" type=\"%s\"%s></xsd:element>\n",
map_sql_identifier_to_xml_name(NameStr(tupdesc->attrs[i]->attname),
true, false),
map_sql_type_to_xml_name(tupdesc->attrs[i]->atttypid, -1),
nulls ? " nillable=\"true\"" : " minOccurs=\"0\"");
}
appendStringInfoString(&result,
" </xsd:sequence>\n"
"</xsd:complexType>\n\n");
if (!tableforest)
{
appendStringInfo(&result,
"<xsd:complexType name=\"%s\">\n"
" <xsd:sequence>\n"
" <xsd:element name=\"row\" type=\"%s\" minOccurs=\"0\" maxOccurs=\"unbounded\"/>\n"
" </xsd:sequence>\n"
"</xsd:complexType>\n\n",
tabletypename, rowtypename);
appendStringInfo(&result,
"<xsd:element name=\"%s\" type=\"%s\"/>\n\n",
xmltn, tabletypename);
}
else
appendStringInfo(&result,
"<xsd:element name=\"%s\" type=\"%s\"/>\n\n",
xmltn, rowtypename);
xsd_schema_element_end(&result);
return result.data;
}
/*
* Map an SQL schema to XML Schema data types; see SQL/XML section
* 9.7.
*/
static const char *
map_sql_schema_to_xmlschema_types(Oid nspid, List *relid_list, bool nulls,
bool tableforest, const char *targetns)
{
char *dbname;
char *nspname;
char *xmlsn;
char *schematypename;
StringInfoData result;
ListCell *cell;
dbname = get_database_name(MyDatabaseId);
nspname = get_namespace_name(nspid);
initStringInfo(&result);
xmlsn = map_sql_identifier_to_xml_name(nspname, true, false);
schematypename = map_multipart_sql_identifier_to_xml_name("SchemaType",
dbname,
nspname,
NULL);
appendStringInfo(&result,
"<xsd:complexType name=\"%s\">\n", schematypename);
if (!tableforest)
appendStringInfoString(&result,
" <xsd:all>\n");
else
appendStringInfoString(&result,
" <xsd:sequence>\n");
foreach(cell, relid_list)
{
Oid relid = lfirst_oid(cell);
char *relname = get_rel_name(relid);
char *xmltn = map_sql_identifier_to_xml_name(relname, true, false);
char *tabletypename = map_multipart_sql_identifier_to_xml_name(tableforest ? "RowType" : "TableType",
dbname,
nspname,
relname);
if (!tableforest)
appendStringInfo(&result,
" <xsd:element name=\"%s\" type=\"%s\"/>\n",
xmltn, tabletypename);
else
appendStringInfo(&result,
" <xsd:element name=\"%s\" type=\"%s\" minOccurs=\"0\" maxOccurs=\"unbounded\"/>\n",
xmltn, tabletypename);
}
if (!tableforest)
appendStringInfoString(&result,
" </xsd:all>\n");
else
appendStringInfoString(&result,
" </xsd:sequence>\n");
appendStringInfoString(&result,
"</xsd:complexType>\n\n");
appendStringInfo(&result,
"<xsd:element name=\"%s\" type=\"%s\"/>\n\n",
xmlsn, schematypename);
return result.data;
}
/*
* Map an SQL catalog to XML Schema data types; see SQL/XML section
* 9.8.
*/
static const char *
map_sql_catalog_to_xmlschema_types(List *nspid_list, bool nulls,
bool tableforest, const char *targetns)
{
char *dbname;
char *xmlcn;
char *catalogtypename;
StringInfoData result;
ListCell *cell;
dbname = get_database_name(MyDatabaseId);
initStringInfo(&result);
xmlcn = map_sql_identifier_to_xml_name(dbname, true, false);
catalogtypename = map_multipart_sql_identifier_to_xml_name("CatalogType",
dbname,
NULL,
NULL);
appendStringInfo(&result,
"<xsd:complexType name=\"%s\">\n", catalogtypename);
appendStringInfoString(&result,
" <xsd:all>\n");
foreach(cell, nspid_list)
{
Oid nspid = lfirst_oid(cell);
char *nspname = get_namespace_name(nspid);
char *xmlsn = map_sql_identifier_to_xml_name(nspname, true, false);
char *schematypename = map_multipart_sql_identifier_to_xml_name("SchemaType",
dbname,
nspname,
NULL);
appendStringInfo(&result,
" <xsd:element name=\"%s\" type=\"%s\"/>\n",
xmlsn, schematypename);
}
appendStringInfoString(&result,
" </xsd:all>\n");
appendStringInfoString(&result,
"</xsd:complexType>\n\n");
appendStringInfo(&result,
"<xsd:element name=\"%s\" type=\"%s\"/>\n\n",
xmlcn, catalogtypename);
return result.data;
}
/*
* Map an SQL data type to an XML name; see SQL/XML:2003 section 9.9.
*/
static const char *
map_sql_type_to_xml_name(Oid typeoid, int typmod)
{
StringInfoData result;
initStringInfo(&result);
switch (typeoid)
{
case BPCHAROID:
if (typmod == -1)
appendStringInfo(&result, "CHAR");
else
appendStringInfo(&result, "CHAR_%d", typmod - VARHDRSZ);
break;
case VARCHAROID:
if (typmod == -1)
appendStringInfo(&result, "VARCHAR");
else
appendStringInfo(&result, "VARCHAR_%d", typmod - VARHDRSZ);
break;
case NUMERICOID:
if (typmod == -1)
appendStringInfo(&result, "NUMERIC");
else
appendStringInfo(&result, "NUMERIC_%d_%d",
((typmod - VARHDRSZ) >> 16) & 0xffff,
(typmod - VARHDRSZ) & 0xffff);
break;
case INT4OID:
appendStringInfo(&result, "INTEGER");
break;
case INT2OID:
appendStringInfo(&result, "SMALLINT");
break;
case INT8OID:
appendStringInfo(&result, "BIGINT");
break;
case FLOAT4OID:
appendStringInfo(&result, "REAL");
break;
case FLOAT8OID:
appendStringInfo(&result, "DOUBLE");
break;
case BOOLOID:
appendStringInfo(&result, "BOOLEAN");
break;
case TIMEOID:
if (typmod == -1)
appendStringInfo(&result, "TIME");
else
appendStringInfo(&result, "TIME_%d", typmod);
break;
case TIMETZOID:
if (typmod == -1)
appendStringInfo(&result, "TIME_WTZ");
else
appendStringInfo(&result, "TIME_WTZ_%d", typmod);
break;
case TIMESTAMPOID:
if (typmod == -1)
appendStringInfo(&result, "TIMESTAMP");
else
appendStringInfo(&result, "TIMESTAMP_%d", typmod);
break;
case TIMESTAMPTZOID:
if (typmod == -1)
appendStringInfo(&result, "TIMESTAMP_WTZ");
else
appendStringInfo(&result, "TIMESTAMP_WTZ_%d", typmod);
break;
case DATEOID:
appendStringInfo(&result, "DATE");
break;
case XMLOID:
appendStringInfo(&result, "XML");
break;
default:
{
HeapTuple tuple;
Form_pg_type typtuple;
tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typeoid));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for type %u", typeoid);
typtuple = (Form_pg_type) GETSTRUCT(tuple);
appendStringInfoString(&result,
map_multipart_sql_identifier_to_xml_name((typtuple->typtype == TYPTYPE_DOMAIN) ? "Domain" : "UDT",
get_database_name(MyDatabaseId),
get_namespace_name(typtuple->typnamespace),
NameStr(typtuple->typname)));
ReleaseSysCache(tuple);
}
}
return result.data;
}
/*
* Map a collection of SQL data types to XML Schema data types; see
* SQL/XML:2002 section 9.10.
*/
static const char *
map_sql_typecoll_to_xmlschema_types(List *tupdesc_list)
{
List *uniquetypes = NIL;
int i;
StringInfoData result;
ListCell *cell0;
/* extract all column types used in the set of TupleDescs */
foreach(cell0, tupdesc_list)
{
TupleDesc tupdesc = (TupleDesc) lfirst(cell0);
for (i = 0; i < tupdesc->natts; i++)
{
if (tupdesc->attrs[i]->attisdropped)
continue;
uniquetypes = list_append_unique_oid(uniquetypes,
tupdesc->attrs[i]->atttypid);
}
}
/* add base types of domains */
foreach(cell0, uniquetypes)
{
Oid typid = lfirst_oid(cell0);
Oid basetypid = getBaseType(typid);
if (basetypid != typid)
uniquetypes = list_append_unique_oid(uniquetypes, basetypid);
}
/* Convert to textual form */
initStringInfo(&result);
foreach(cell0, uniquetypes)
{
appendStringInfo(&result, "%s\n",
map_sql_type_to_xmlschema_type(lfirst_oid(cell0),
-1));
}
return result.data;
}
/*
* Map an SQL data type to a named XML Schema data type; see SQL/XML
* sections 9.11 and 9.15.
*
* (The distinction between 9.11 and 9.15 is basically that 9.15 adds
* a name attribute, which this function does. The name-less version
* 9.11 doesn't appear to be required anywhere.)
*/
static const char *
map_sql_type_to_xmlschema_type(Oid typeoid, int typmod)
{
StringInfoData result;
const char *typename = map_sql_type_to_xml_name(typeoid, typmod);
initStringInfo(&result);
if (typeoid == XMLOID)
{
appendStringInfo(&result,
"<xsd:complexType mixed=\"true\">\n"
" <xsd:sequence>\n"
" <xsd:any name=\"element\" minOccurs=\"0\" maxOccurs=\"unbounded\" processContents=\"skip\"/>\n"
" </xsd:sequence>\n"
"</xsd:complexType>\n");
}
else
{
appendStringInfo(&result,
"<xsd:simpleType name=\"%s\">\n", typename);
switch (typeoid)
{
case BPCHAROID:
case VARCHAROID:
case TEXTOID:
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:string\">\n");
if (typmod != -1)
appendStringInfo(&result,
" <xsd:maxLength value=\"%d\"/>\n",
typmod - VARHDRSZ);
appendStringInfo(&result,
" </xsd:restriction>\n");
break;
case BYTEAOID:
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:%s\">\n"
" </xsd:restriction>\n",
xmlbinary == XMLBINARY_BASE64 ? "base64Binary" : "hexBinary");
break;
case NUMERICOID:
if (typmod != -1)
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:decimal\">\n"
" <xsd:totalDigits value=\"%d\"/>\n"
" <xsd:fractionDigits value=\"%d\"/>\n"
" </xsd:restriction>\n",
((typmod - VARHDRSZ) >> 16) & 0xffff,
(typmod - VARHDRSZ) & 0xffff);
break;
case INT2OID:
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:short\">\n"
" <xsd:maxInclusive value=\"%d\"/>\n"
" <xsd:minInclusive value=\"%d\"/>\n"
" </xsd:restriction>\n",
SHRT_MAX, SHRT_MIN);
break;
case INT4OID:
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:int\">\n"
" <xsd:maxInclusive value=\"%d\"/>\n"
" <xsd:minInclusive value=\"%d\"/>\n"
" </xsd:restriction>\n",
INT_MAX, INT_MIN);
break;
case INT8OID:
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:long\">\n"
" <xsd:maxInclusive value=\"" INT64_FORMAT "\"/>\n"
" <xsd:minInclusive value=\"" INT64_FORMAT "\"/>\n"
" </xsd:restriction>\n",
(((uint64) 1) << (sizeof(int64) * 8 - 1)) - 1,
(((uint64) 1) << (sizeof(int64) * 8 - 1)));
break;
case FLOAT4OID:
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:float\"></xsd:restriction>\n");
break;
case FLOAT8OID:
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:double\"></xsd:restriction>\n");
break;
case BOOLOID:
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:boolean\"></xsd:restriction>\n");
break;
case TIMEOID:
case TIMETZOID:
{
const char *tz = (typeoid == TIMETZOID ? "(+|-)\\p{Nd}{2}:\\p{Nd}{2}" : "");
if (typmod == -1)
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:time\">\n"
" <xsd:pattern value=\"\\p{Nd}{2}:\\p{Nd}{2}:\\p{Nd}{2}(.\\p{Nd}+)?%s\"/>\n"
" </xsd:restriction>\n", tz);
else if (typmod == 0)
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:time\">\n"
" <xsd:pattern value=\"\\p{Nd}{2}:\\p{Nd}{2}:\\p{Nd}{2}%s\"/>\n"
" </xsd:restriction>\n", tz);
else
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:time\">\n"
" <xsd:pattern value=\"\\p{Nd}{2}:\\p{Nd}{2}:\\p{Nd}{2}.\\p{Nd}{%d}%s\"/>\n"
" </xsd:restriction>\n", typmod - VARHDRSZ, tz);
break;
}
case TIMESTAMPOID:
case TIMESTAMPTZOID:
{
const char *tz = (typeoid == TIMESTAMPTZOID ? "(+|-)\\p{Nd}{2}:\\p{Nd}{2}" : "");
if (typmod == -1)
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:dateTime\">\n"
" <xsd:pattern value=\"\\p{Nd}{4}-\\p{Nd}{2}-\\p{Nd}{2}T\\p{Nd}{2}:\\p{Nd}{2}:\\p{Nd}{2}(.\\p{Nd}+)?%s\"/>\n"
" </xsd:restriction>\n", tz);
else if (typmod == 0)
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:dateTime\">\n"
" <xsd:pattern value=\"\\p{Nd}{4}-\\p{Nd}{2}-\\p{Nd}{2}T\\p{Nd}{2}:\\p{Nd}{2}:\\p{Nd}{2}%s\"/>\n"
" </xsd:restriction>\n", tz);
else
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:dateTime\">\n"
" <xsd:pattern value=\"\\p{Nd}{4}-\\p{Nd}{2}-\\p{Nd}{2}T\\p{Nd}{2}:\\p{Nd}{2}:\\p{Nd}{2}.\\p{Nd}{%d}%s\"/>\n"
" </xsd:restriction>\n", typmod - VARHDRSZ, tz);
break;
}
case DATEOID:
appendStringInfo(&result,
" <xsd:restriction base=\"xsd:date\">\n"
" <xsd:pattern value=\"\\p{Nd}{4}-\\p{Nd}{2}-\\p{Nd}{2}\"/>\n"
" </xsd:restriction>\n");
break;
default:
if (get_typtype(typeoid) == TYPTYPE_DOMAIN)
{
Oid base_typeoid;
int32 base_typmod = -1;
base_typeoid = getBaseTypeAndTypmod(typeoid, &base_typmod);
appendStringInfo(&result,
" <xsd:restriction base=\"%s\"/>\n",
map_sql_type_to_xml_name(base_typeoid, base_typmod));
}
break;
}
appendStringInfo(&result,
"</xsd:simpleType>\n");
}
return result.data;
}
/*
* Map an SQL row to an XML element, taking the row from the active
* SPI cursor. See also SQL/XML:2003 section 9.12.
*/
static void
SPI_sql_row_to_xmlelement(int rownum, StringInfo result, char *tablename,
bool nulls, bool tableforest,
const char *targetns, bool top_level)
{
int i;
char *xmltn;
if (tablename)
xmltn = map_sql_identifier_to_xml_name(tablename, true, false);
else
{
if (tableforest)
xmltn = "row";
else
xmltn = "table";
}
if (tableforest)
xmldata_root_element_start(result, xmltn, NULL, targetns, top_level);
else
appendStringInfoString(result, "<row>\n");
for (i = 1; i <= SPI_tuptable->tupdesc->natts; i++)
{
char *colname;
Datum colval;
bool isnull;
colname = map_sql_identifier_to_xml_name(SPI_fname(SPI_tuptable->tupdesc, i),
true, false);
colval = SPI_getbinval(SPI_tuptable->vals[rownum],
SPI_tuptable->tupdesc,
i,
&isnull);
if (isnull)
{
if (nulls)
appendStringInfo(result, " <%s xsi:nil=\"true\"/>\n", colname);
}
else
appendStringInfo(result, " <%s>%s</%s>\n",
colname,
map_sql_value_to_xml_value(colval,
SPI_gettypeid(SPI_tuptable->tupdesc, i), true),
colname);
}
if (tableforest)
{
xmldata_root_element_end(result, xmltn);
appendStringInfoChar(result, '\n');
}
else
appendStringInfoString(result, "</row>\n\n");
}
/*
* XPath related functions
*/
#ifdef USE_LIBXML
/*
* Convert XML node to text (dump subtree in case of element,
* return value otherwise)
*/
static text *
xml_xmlnodetoxmltype(xmlNodePtr cur)
{
xmltype *result;
if (cur->type == XML_ELEMENT_NODE)
{
xmlBufferPtr buf;
buf = xmlBufferCreate();
PG_TRY();
{
xmlNodeDump(buf, NULL, cur, 0, 1);
result = xmlBuffer_to_xmltype(buf);
}
PG_CATCH();
{
xmlBufferFree(buf);
PG_RE_THROW();
}
PG_END_TRY();
xmlBufferFree(buf);
}
else
{
xmlChar *str;
str = xmlXPathCastNodeToString(cur);
PG_TRY();
{
result = (xmltype *) cstring_to_text((char *) str);
}
PG_CATCH();
{
xmlFree(str);
PG_RE_THROW();
}
PG_END_TRY();
xmlFree(str);
}
return result;
}
#endif
/*
* Common code for xpath() and xmlexists()
*
* Evaluate XPath expression and return number of nodes in res_items
* and array of XML values in astate.
*
* It is up to the user to ensure that the XML passed is in fact
* an XML document - XPath doesn't work easily on fragments without
* a context node being known.
*/
#ifdef USE_LIBXML
static void
xpath_internal(text *xpath_expr_text, xmltype *data, ArrayType *namespaces,
int *res_nitems, ArrayBuildState **astate)
{
xmlParserCtxtPtr ctxt = NULL;
xmlDocPtr doc = NULL;
xmlXPathContextPtr xpathctx = NULL;
xmlXPathCompExprPtr xpathcomp = NULL;
xmlXPathObjectPtr xpathobj = NULL;
char *datastr;
int32 len;
int32 xpath_len;
xmlChar *string;
xmlChar *xpath_expr;
int i;
int ndim;
Datum *ns_names_uris;
bool *ns_names_uris_nulls;
int ns_count;
/*
* Namespace mappings are passed as text[]. If an empty array is passed
* (ndim = 0, "0-dimensional"), then there are no namespace mappings.
* Else, a 2-dimensional 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']].
*/
ndim = namespaces ? ARR_NDIM(namespaces) : 0;
if (ndim != 0)
{
int *dims;
dims = ARR_DIMS(namespaces);
if (ndim != 2 || dims[1] != 2)
ereport(ERROR,
(errcode(ERRCODE_DATA_EXCEPTION),
errmsg("invalid array for XML namespace mapping"),
errdetail("The array must be two-dimensional with length of the second axis equal to 2.")));
Assert(ARR_ELEMTYPE(namespaces) == TEXTOID);
deconstruct_array(namespaces, TEXTOID, -1, false, 'i',
&ns_names_uris, &ns_names_uris_nulls,
&ns_count);
Assert((ns_count % 2) == 0); /* checked above */
ns_count /= 2; /* count pairs only */
}
else
{
ns_names_uris = NULL;
ns_names_uris_nulls = NULL;
ns_count = 0;
}
datastr = VARDATA(data);
len = VARSIZE(data) - VARHDRSZ;
xpath_len = VARSIZE(xpath_expr_text) - VARHDRSZ;
if (xpath_len == 0)
ereport(ERROR,
(errcode(ERRCODE_DATA_EXCEPTION),
errmsg("empty XPath expression")));
string = (xmlChar *) palloc((len + 1) * sizeof(xmlChar));
memcpy(string, datastr, len);
string[len] = '\0';
xpath_expr = (xmlChar *) palloc((xpath_len + 1) * sizeof(xmlChar));
memcpy(xpath_expr, VARDATA(xpath_expr_text), xpath_len);
xpath_expr[xpath_len] = '\0';
pg_xml_init();
xmlInitParser();
PG_TRY();
{
/*
* redundant XML parsing (two parsings for the same value during one
* command execution are possible)
*/
ctxt = xmlNewParserCtxt();
if (ctxt == NULL)
xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate parser context");
doc = xmlCtxtReadMemory(ctxt, (char *) string, len, NULL, NULL, 0);
if (doc == NULL)
xml_ereport(ERROR, ERRCODE_INVALID_XML_DOCUMENT,
"could not parse XML document");
xpathctx = xmlXPathNewContext(doc);
if (xpathctx == NULL)
xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
"could not allocate XPath context");
xpathctx->node = xmlDocGetRootElement(doc);
if (xpathctx->node == NULL)
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
"could not find root XML element");
/* register namespaces, if any */
if (ns_count > 0)
{
for (i = 0; i < ns_count; i++)
{
char *ns_name;
char *ns_uri;
if (ns_names_uris_nulls[i * 2] ||
ns_names_uris_nulls[i * 2 + 1])
ereport(ERROR,
(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
errmsg("neither namespace name nor URI may be null")));
ns_name = TextDatumGetCString(ns_names_uris[i * 2]);
ns_uri = TextDatumGetCString(ns_names_uris[i * 2 + 1]);
if (xmlXPathRegisterNs(xpathctx,
(xmlChar *) ns_name,
(xmlChar *) ns_uri) != 0)
ereport(ERROR, /* is this an internal error??? */
(errmsg("could not register XML namespace with name \"%s\" and URI \"%s\"",
ns_name, ns_uri)));
}
}
xpathcomp = xmlXPathCompile(xpath_expr);
if (xpathcomp == NULL) /* TODO: show proper XPath error details */
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
"invalid XPath expression");
/*
* Version 2.6.27 introduces a function named
* xmlXPathCompiledEvalToBoolean, which would be enough for
* xmlexists, but we can derive the existence by whether any
* nodes are returned, thereby preventing a library version
* upgrade and keeping the code the same.
*/
xpathobj = xmlXPathCompiledEval(xpathcomp, xpathctx);
if (xpathobj == NULL) /* TODO: reason? */
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
"could not create XPath object");
/* return empty array in cases when nothing is found */
if (xpathobj->nodesetval == NULL)
*res_nitems = 0;
else
*res_nitems = xpathobj->nodesetval->nodeNr;
if (*res_nitems && astate)
{
*astate = NULL;
for (i = 0; i < xpathobj->nodesetval->nodeNr; i++)
{
Datum elem;
bool elemisnull = false;
elem = PointerGetDatum(xml_xmlnodetoxmltype(xpathobj->nodesetval->nodeTab[i]));
*astate = accumArrayResult(*astate, elem,
elemisnull, XMLOID,
CurrentMemoryContext);
}
}
}
PG_CATCH();
{
if (xpathobj)
xmlXPathFreeObject(xpathobj);
if (xpathcomp)
xmlXPathFreeCompExpr(xpathcomp);
if (xpathctx)
xmlXPathFreeContext(xpathctx);
if (doc)
xmlFreeDoc(doc);
if (ctxt)
xmlFreeParserCtxt(ctxt);
PG_RE_THROW();
}
PG_END_TRY();
xmlXPathFreeObject(xpathobj);
xmlXPathFreeCompExpr(xpathcomp);
xmlXPathFreeContext(xpathctx);
xmlFreeDoc(doc);
xmlFreeParserCtxt(ctxt);
}
#endif /* USE_LIBXML */
/*
* Evaluate XPath expression and return array of XML values.
*
* As we have no support of XQuery sequences yet, this function seems
* to be the most useful one (array of XML functions plays a role of
* some kind of substitution for XQuery sequences).
*/
Datum
xpath(PG_FUNCTION_ARGS)
{
#ifdef USE_LIBXML
text *xpath_expr_text = PG_GETARG_TEXT_P(0);
xmltype *data = PG_GETARG_XML_P(1);
ArrayType *namespaces = PG_GETARG_ARRAYTYPE_P(2);
int res_nitems;
ArrayBuildState *astate;
xpath_internal(xpath_expr_text, data, namespaces,
&res_nitems, &astate);
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;
#endif
}
/*
* Determines if the node specified by the supplied XPath exists
* in a given XML document, returning a boolean.
*/
Datum xmlexists(PG_FUNCTION_ARGS)
{
#ifdef USE_LIBXML
text *xpath_expr_text = PG_GETARG_TEXT_P(0);
xmltype *data = PG_GETARG_XML_P(1);
int res_nitems;
xpath_internal(xpath_expr_text, data, NULL,
&res_nitems, NULL);
PG_RETURN_BOOL(res_nitems > 0);
#else
NO_XML_SUPPORT();
return 0;
#endif
}
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