Function xml_in 

pub fn xml_in(
    text: &[u8],
    document: bool,
    warn: &mut dyn FnMut(String),
) -> Result<(), TypeError>

xml_in, which checks that the text is a well formed document when document is true, or well formed content when it is false. The text ends at the first zero byte, as libxml2 sees it. warn gets the text of each warning of libxml2, which PostgreSQL reports with the SQLSTATE 01000 before the error.

Errors

2200M for a document and 2200N for content that is not well formed, with the messages of libxml2 as the detail.