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Fix xmlelement() to initialize libxml correctly before using it, and to avoid

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assuming that evaluation of its input expressions won't change the state of
libxml.  This requires refactoring xml_init() to not call xmlInitParser(),
since now not all of its callers want that.  I also tweaked things to avoid
repeated execution of one-time-only tests inside xml_init(), though this is
mostly for clarity rather than in hopes of saving any noticeable amount of
runtime.  Per report from Sheikh Amjad and subsequent discussion.
In passing, fix a couple of inadequately schema-qualified queries.
REL8_3_STABLE
Tom Lane 18 years ago
parent bcb3852c33
commit 85f807d782
1 changed files with 120 additions and 55 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 175
      src/backend/utils/adt/xml.c

175
src/backend/utils/adt/xml.c
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@ -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 1.49 2007/10/13 20:46:47 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.50 2007/11/05 22:23:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -73,6 +73,10 @@
#include "utils/xml.h"
/* GUC variables */
XmlBinaryType xmlbinary;
XmlOptionType xmloption;
#ifdef USE_LIBXML
static StringInfo xml_err_buf = NULL;
@ -104,11 +108,6 @@ 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);
XmlBinaryType xmlbinary;
XmlOptionType xmloption;
#define NO_XML_SUPPORT() \
ereport(ERROR, \
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED), \
@ -217,7 +216,8 @@ xml_out_internal(xmltype *x, pg_enc target_encoding)
}
xml_ereport_by_code(WARNING, ERRCODE_INTERNAL_ERROR,
"could not parse XML declaration in stored value", res_code);
"could not parse XML declaration in stored value",
res_code);
#endif
return str;
}
@ -540,45 +540,84 @@ 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;
bool isnull;
xmltype *result;
Datum value;
char *str;
xmlBufferPtr buf;
xmlTextWriterPtr writer;
buf = xmlBufferCreate();
writer = xmlNewTextWriterMemory(buf, 0);
xmlTextWriterStartElement(writer, (xmlChar *) xexpr->name);
/*
* 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;
forboth(arg, xmlExpr->named_args, narg, xexpr->arg_names)
foreach(arg, xmlExpr->named_args)
{
ExprState *e = (ExprState *) lfirst(arg);
char *argname = strVal(lfirst(narg));
Datum value;
bool isnull;
char *str;
value = ExecEvalExpr(e, econtext, &isnull, NULL);
if (!isnull)
{
if (isnull)
str = NULL;
else
str = OutputFunctionCall(&xmlExpr->named_outfuncs[i], value);
xmlTextWriterWriteAttribute(writer, (xmlChar *) argname, (xmlChar *) str);
pfree(str);
}
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)
xmlTextWriterWriteRaw(writer, (xmlChar *) map_sql_value_to_xml_value(value, exprType((Node *) e->expr)));
{
str = map_sql_value_to_xml_value(value,
exprType((Node *) e->expr));
arg_strings = lappend(arg_strings, str);
}
}
/* now safe to run libxml */
xml_init();
buf = xmlBufferCreate();
writer = xmlNewTextWriterMemory(buf, 0);
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);
pfree(str);
}
}
foreach(arg, arg_strings)
{
char *str = (char *) lfirst(arg);
xmlTextWriterWriteRaw(writer, (xmlChar *) str);
}
xmlTextWriterEndElement(writer);
@ -586,6 +625,7 @@ xmlelement(XmlExprState *xmlExpr, ExprContext *econtext)
result = xmlBuffer_to_xmltype(buf);
xmlBufferFree(buf);
return result;
#else
NO_XML_SUPPORT();
@ -733,9 +773,10 @@ xmlvalidate(PG_FUNCTION_ARGS)
xml_init();
/* We use a PG_TRY block to ensure libxml is cleaned up on error */
/* We use a PG_TRY block to ensure libxml parser is cleaned up on error */
PG_TRY();
{
xmlInitParser();
ctxt = xmlNewParserCtxt();
if (ctxt == NULL)
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
@ -860,43 +901,64 @@ xml_is_document(xmltype *arg)
#ifdef USE_LIBXML
/*
* Container for some init stuff (not good design!)
* TODO xmlChar is utf8-char, make proper tuning (initdb with enc!=utf8 and check)
* Set up for use of libxml --- this should be called by each function that
* is about to use libxml facilities.
*
* TODO: xmlChar is utf8-char, make proper tuning (initdb with enc!=utf8 and
* check)
*/
static void
xml_init(void)
{
/*
* 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))));
static bool first_time = true;
if (xml_err_buf == NULL)
if (first_time)
{
/* First time through: create error buffer in permanent context */
/* 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);
/* Set up memory allocation our way, too */
xmlMemSetup(xml_pfree, xml_palloc, xml_repalloc, xml_pstrdup);
/* 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);
}
/* Now that xml_err_buf exists, safe to call xml_errorHandler */
xmlSetGenericErrorFunc(NULL, xml_errorHandler);
xmlMemSetup(xml_pfree, xml_palloc, xml_repalloc, xml_pstrdup);
xmlInitParser();
LIBXML_TEST_VERSION;
/*
* We re-establish the callback functions 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);
xmlMemSetup(xml_pfree, xml_palloc, xml_repalloc, xml_pstrdup);
}
}
@ -1071,9 +1133,10 @@ print_xml_decl(StringInfo buf, const xmlChar *version, pg_enc encoding, int stan
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 */
/*
* 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)
@ -1115,9 +1178,10 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace, xml
xml_init();
/* We use a PG_TRY block to ensure libxml is cleaned up on error */
/* We use a PG_TRY block to ensure libxml parser is cleaned up on error */
PG_TRY();
{
xmlInitParser();
ctxt = xmlNewParserCtxt();
if (ctxt == NULL)
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
@ -1780,7 +1844,7 @@ schema_get_xml_visible_tables(Oid nspid)
StringInfoData query;
initStringInfo(&query);
appendStringInfo(&query, "SELECT oid FROM pg_class WHERE relnamespace = %u AND relkind IN ('r', 'v') AND has_table_privilege (oid, 'SELECT') ORDER BY relname;", nspid);
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);
}
@ -1792,7 +1856,7 @@ schema_get_xml_visible_tables(Oid nspid)
*/
#define XML_VISIBLE_SCHEMAS_EXCLUDE "nspname LIKE 'pg_%' ESCAPE '' OR nspname = 'information_schema'"
#define XML_VISIBLE_SCHEMAS "SELECT oid FROM pg_namespace WHERE has_schema_privilege (oid, 'USAGE') AND NOT (" XML_VISIBLE_SCHEMAS_EXCLUDE ")"
#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 *
@ -1806,7 +1870,7 @@ 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_class WHERE relkind IN ('r', 'v') AND has_table_privilege (pg_class.oid, 'SELECT') AND relnamespace IN (" XML_VISIBLE_SCHEMAS ");");
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 ");");
}
@ -2973,7 +3037,6 @@ SPI_sql_row_to_xmlelement(int rownum, StringInfo result, char *tablename, bool n
{
if (nulls)
appendStringInfo(result, " <%s xsi:nil='true'/>\n", colname);
}
else
appendStringInfo(result, " <%s>%s</%s>\n",
@ -3170,10 +3233,12 @@ xpath(PG_FUNCTION_ARGS)
xml_init();
/* We use a PG_TRY block to ensure libxml parser is cleaned up on error */
PG_TRY();
{
xmlInitParser();
/*
* redundant XML parsing (two parsings for the same value *
* redundant XML parsing (two parsings for the same value
* during one command execution are possible)
*/
ctxt = xmlNewParserCtxt();

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