MDEV-37262 XMLISVALID() schema validation function by abarkov · Pull Request #5171 · MariaDB/server

abarkov · 2026-06-03T10:47:39Z

No description provided.

XMLTYPE column added. Type_handler::get_column_attributes() added so parser can check if unexpected attributes were specified for the UDT column.

XMLVALID function added to the XMLTYPE plugin.

CLAassistant · 2026-06-03T10:47:46Z

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Code Review

This pull request introduces a new 'xmltype' data type plugin and an 'XMLISVALID' function, alongside a validation mechanism to prevent unsupported attributes (like length, decimals, character set, or SRID) on various data types (e.g., 'vector', 'INET4', 'INET6', 'UUID'). While the changes are valuable, several critical issues must be addressed: the source file 'item_func_xml_isvalid.cc' is missing from the PR, causing compilation failures; the 'typeid' comparison in 'Item_char_typecast::eq' incorrectly compares pointer types instead of dereferenced objects; a potential null pointer dereference exists on 'last_field' in 'LEX::set_field_type_udt'; and there is a potential data race on the static 'xml_handler' initialization. Additionally, checking the string length before parsing in 'Item_xmltype_typecast::val_str' would improve consistency and robustness.

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gemini-code-assist · 2026-06-03T10:50:16Z

+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1335  USA
+
+MYSQL_ADD_PLUGIN(type_xmltype
+                 plugin.cc sql_type_xmltype.cc item_func_xml_isvalid.cc


The file item_func_xml_isvalid.cc is listed as a source file for the type_xmltype plugin, but it is missing from the pull request. This will cause compilation and linking to fail because the implementation of Item_func_xml_isvalid methods (such as val_bool and fix_length_and_dec) is not provided.

gemini-code-assist · 2026-06-03T10:50:16Z

    return 1;
-  if (item->type() != FUNC_ITEM ||
-      functype() != ((Item_func*)item)->functype())
+  if (typeid(this) != typeid(item))


Using typeid(this) != typeid(item) compares the pointer types (Item_char_typecast* vs const Item*) instead of the dynamic types of the objects themselves. Since these pointer types are statically different, this check will always evaluate to true (and return 0), breaking the correctness of the eq method. To compare the dynamic types of the polymorphic objects, you must dereference the pointers.

if (typeid(*this) != typeid(*item))

gemini-code-assist · 2026-06-03T10:50:16Z

+  if (!res)
+    return NULL;
+
+  if (check_parse_xml(res->ptr(), res->length(), res->charset()) != MY_XML_OK)


For consistency with Field_xmltype::store and to prevent potential null-pointer dereferences or unnecessary parsing of empty/too-short strings, check if res->length() < 4 before calling check_parse_xml.

if (res->length() < 4 || check_parse_xml(res->ptr(), res->length(), res->charset()) != MY_XML_OK)

gemini-code-assist · 2026-06-03T10:50:16Z

+  column_attributes|= last_field->get_attr_uint32(0) ?
+                        Type_handler::ATTR_SRID : 0;


Defensive programming: last_field can potentially be NULL in certain parser contexts or error states. It should be checked for NULL before calling get_attr_uint32(0) to avoid a potential null pointer dereference crash.

column_attributes|= (last_field && last_field->get_attr_uint32(0)) ? Type_handler::ATTR_SRID : 0;

gemini-code-assist · 2026-06-03T10:50:16Z

+  if (!xml_handler)
+    xml_handler= Type_handler::handler_by_name(thd, name);


There is a potential data race on the static member Item_func_xml_update::xml_handler when multiple threads concurrently execute fix_length_and_dec and initialize it. While the race might be benign (writing the same pointer), it is technically undefined behavior in C++ and can be flagged by TSAN. Consider making xml_handler a std::atomic<const Type_handler*> or using a thread-safe initialization pattern.

Copilot

Pull request overview

This PR introduces an XMLTYPE data type plugin and an XMLISVALID() function for XML Schema validation, while extending the SQL parser/type system to better control which column/type attributes are allowed for plugin-defined (UDT) types.

Changes:

Add a new type_xmltype plugin implementing XMLTYPE, including casting behavior and replication/type aggregation support.
Add XMLISVALID(xml, schema[, element]) as a native function with extensive mysql-test coverage for validation behavior.
Introduce attribute-allowlisting for UDTs via Type_handler::get_column_attributes() and enforce it in the parser, with a new ER_UNSUPPORTED_DATA_TYPE_ATTRIBUTE error.

Reviewed changes

Copilot reviewed 36 out of 37 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
strings/xml.c	Propagate XML value-handler failures for text nodes during parsing.
sql/table.cc	Validate assignability of VCOL default expressions when unpacking from FRM.
sql/sql_yacc.yy	Extend UDT grammar to accept `opt_binary` and adjust parser expectations.
sql/sql_type.h	Add `column_attributes` flags and default `get_column_attributes()` API.
sql/sql_type_vector.h	Restrict VECTOR UDT attributes to length-only.
sql/sql_type_vector.cc	Tighten VECTOR attribute handling and enforce binary charset internally.
sql/sql_type_geom.h	Restrict GEOMETRY attributes (length/dec/srid).
sql/sql_type_fixedbin.h	Restrict fixed binary type bundle attributes (none).
sql/sql_lex.h	Extend LEX APIs to pass charset/collation attributes into UDT type setup.
sql/sql_lex.cc	Enforce UDT attribute allowlist and add CAST UDT charset validation.
sql/share/errmsg-utf8.txt	Add `ER_UNSUPPORTED_DATA_TYPE_ATTRIBUTE` message.
sql/item_xmlfunc.h	Adjust UpdateXML item typing to support XMLTYPE result typing.
sql/item_xmlfunc.cc	Implement UpdateXML result type handler lookup/caching.
sql/item_timefunc.h	Expose `Item_char_typecast::print_charset()` for reuse by XMLTYPE cast printing.
sql/item_timefunc.cc	Refactor charset-printing out of Item_char_typecast::print().
plugin/type_xmltype/CMakeLists.txt	Build definition for new XMLTYPE plugin sources.
plugin/type_xmltype/plugin.cc	Register `xmltype` data type plugin and `XMLISVALID` function plugin.
plugin/type_xmltype/sql_type_xmltype.h	Declare `Type_handler_xmltype`, `Field_xmltype`, and XMLISVALID item types.
plugin/type_xmltype/sql_type_xmltype.cc	Implement XMLTYPE handler/field/typecast logic and XML well-formedness checks.
plugin/type_xmltype/item_func_xml_isvalid.cc	Implement XML Schema parsing and XML validation execution for XMLISVALID().
plugin/type_xmltype/mysql-test/type_xmltype/type_xmltype.test	Add test coverage for XMLTYPE DDL/DML, casting, and basic validation.
plugin/type_xmltype/mysql-test/type_xmltype/type_xmltype.result	Expected results for XMLTYPE test suite.
plugin/type_xmltype/mysql-test/type_xmltype/type_xmltype_validation.test	Extensive XMLISVALID schema validation test cases.
plugin/type_xmltype/mysql-test/type_xmltype/type_xmltype_validation.result	Expected results for validation suite.
plugin/type_xmltype/mysql-test/type_xmltype/suite.pm	Register the new mysql-test suite for XMLTYPE as default.
plugin/type_uuid/mysql-test/type_uuid/type_uuid.test	Add attribute-rejection tests using new error code for UUID UDT.
plugin/type_uuid/mysql-test/type_uuid/type_uuid.result	Expected results for UUID attribute-rejection tests.
plugin/type_test/plugin.cc	Declare allowed attributes for test UDT handlers.
plugin/type_test/mysql-test/type_test/type_test_int8.test	Add attribute-rejection tests for TEST_INT8 UDT.
plugin/type_test/mysql-test/type_test/type_test_int8.result	Expected results for TEST_INT8 attribute-rejection tests.
plugin/type_inet/mysql-test/type_inet/type_inet6.test	Add attribute-rejection tests for INET6 and adjust a prior test to new behavior.
plugin/type_inet/mysql-test/type_inet/type_inet6.result	Expected results for INET6 attribute-rejection tests.
plugin/type_inet/mysql-test/type_inet/type_inet4.test	Add attribute-rejection tests for INET4.
plugin/type_inet/mysql-test/type_inet/type_inet4.result	Expected results for INET4 attribute-rejection tests.
mysql-test/main/vector2.test	Update VECTOR attribute error expectation to new error code.
mysql-test/main/vector2.result	Expected results reflecting new VECTOR attribute error message.
include/my_xml.h	Add a new parser flag constant intended for “assert well formed” behavior.

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  \r, \n, \t characters.
 */
 #define MY_XML_FLAG_SKIP_TEXT_NORMALIZATION 2
+#define MY_XML_FLAG_ASSERT_WELL_FORMED 4



+const Type_handler *Item_func_xml_update::xml_handler= NULL;
+
+
+bool Item_func_xml_update::fix_length_and_dec(THD *thd)
+{
+  static LEX_CSTRING name= {STRING_WITH_LEN("XMLTYPE")};
+
+  if (!xml_handler)
+    xml_handler= Type_handler::handler_by_name(thd, name);
+
+  return Item_xml_str_func::fix_length_and_dec(thd);
+}
+
+
+const Type_handler *Item_func_xml_update::type_handler() const
+{
+  return xml_handler ? xml_handler : Item_xml_str_func::type_handler();
 }


+  if (!args[1]->const_item())
+  {
+    my_printf_error(ER_UNKNOWN_ERROR,
+                    "Only constant XML Schema-s are supported.", MYF(0));
+    return TRUE;


      if (!(p->flags & MY_XML_FLAG_SKIP_TEXT_NORMALIZATION))
        my_xml_norm_text(&a);
      if (a.beg != a.end)
      {
-        my_xml_value(p,a.beg,(size_t) (a.end-a.beg));
+        if (MY_XML_OK != my_xml_value(p,a.beg,(size_t) (a.end-a.beg)))
+          return MY_XML_ERROR;
      }


Alexey Botchkov added 5 commits February 22, 2026 22:52

MDEV-37261 Basic XML data type.

e82e30b

XMLTYPE column added. Type_handler::get_column_attributes() added so parser can check if unexpected attributes were specified for the UDT column.

fix to the XMLTYPE.

37b3c44

Fix for XMLTYPE.

a0a289b

fix.

20b7507

MDEV-37262 XMLISVALID() schema validation function.

f0f5cf5

XMLVALID function added to the XMLTYPE plugin.

gemini-code-assist Bot reviewed Jun 3, 2026

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MDEV-37262 XMLISVALID() schema validation function#5171

MDEV-37262 XMLISVALID() schema validation function#5171
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		column_attributes\|= last_field->get_attr_uint32(0) ?
		Type_handler::ATTR_SRID : 0;

		if (!xml_handler)
		xml_handler= Type_handler::handler_by_name(thd, name);

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