Synchronous calls in XsdValidatingReader #78802
Description
Description
When using an XmlReader with schema validation enabled in an async context, the underlying XsdValidatingReader still performs synchronous calls. This can lead to an exception when used on a HTTP request body in Kestrel, as it disallows sync IO access by default.
This is similar to #31737 and a bunch of other issues related to sync calls while doing XML (de-)serialization.
Reproduction Steps
Rough example:
var settings = new XmlReaderSettings();
settings.Async = true;
settings.ValidationType = ValidationType.Schema;
settings.Schemas = mySchemaSet;
settings.ValidationFlags |= XmlSchemaValidationFlags.ProcessInlineSchema;
settings.ValidationFlags |= XmlSchemaValidationFlags.ReportValidationWarnings;
settings.ValidationEventHandler += (ValidationEventHandler) ((_, args) =>
{
if (args.Severity == XmlSeverityType.Error)
throw args.Exception;
});
var reader = XmlReader.Create(stream, settings);
while (...)
{
await XNode.ReadFromAsync(reader, CancellationToken.None);
}
Stack trace:
at System.Xml.XmlTextReaderImpl.ReadData()
at System.Xml.XmlTextReaderImpl.ParseText(Int32& startPos, Int32& endPos, Int32& outOrChars)
at System.Xml.XmlTextReaderImpl.FinishPartialValue()
at System.Xml.XmlTextReaderImpl.get_Value()
at System.Xml.XsdValidatingReader.GetStringValue()
at System.Xml.Schema.XmlSchemaValidator.ValidateText(String elementStringValue, XmlValueGetter elementValueGetter)
at System.Xml.Schema.XmlSchemaValidator.ValidateText(XmlValueGetter elementValue)
at System.Xml.XsdValidatingReader.ProcessReaderEventAsync()
at System.Xml.XsdValidatingReader.ReadAsync_Read(Task`1 task)
at System.Xml.XsdValidatingReader.ReadAsync()
at System.Xml.XmlAsyncCheckReader.ReadAsync()
at System.Xml.Linq.XContainer.ReadContentFromAsync(XmlReader r, CancellationToken cancellationToken)
at System.Xml.Linq.XContainer.ReadContentFromAsync(XmlReader r, LoadOptions o, CancellationToken cancellationToken)
at System.Xml.Linq.XElement.ReadElementFromAsync(XmlReader r, LoadOptions o, CancellationToken cancellationTokentoken)
at System.Xml.Linq.XElement.CreateAsync(XmlReader r, CancellationToken cancellationToken)
at System.Xml.Linq.XNode.ReadFromAsyncInternal(XmlReader reader, CancellationToken cancellationToken)
Expected behavior
No synchronous calls (=no synchronous IO access) should be performed.
Actual behavior
Synchronous calls are being performed.
Regression?
No response
Known Workarounds
- Allow synchronous IO access
- Buffer the entire XML stream (XmlSerializerInputFormatter does this for example)
Configuration
No response
Other information
No response