Fix wrong disregarding of not closed markup, such as lone <

Changelog.md

@@ -23,6 +23,8 @@ configuration is serializable.
 
 ### Bug Fixes
 
+- [#622]: Fix wrong disregarding of not closed markup, such as lone `<`.
+
 ### Misc Changes
 
 - [#675]: Minimum supported version of serde raised to 1.0.139
@@ -36,6 +38,7 @@ configuration is serializable.
   - `Error::UnexpectedToken` replaced by `IllFormedError::DoubleHyphenInComment`
 
 [#513]: https://github.com/tafia/quick-xml/issues/513
+[#622]: https://github.com/tafia/quick-xml/issues/622
 [#675]: https://github.com/tafia/quick-xml/pull/675
 [#677]: https://github.com/tafia/quick-xml/pull/677
 

src/reader/async_tokio.rs

@@ -4,13 +4,13 @@
 
 use tokio::io::{self, AsyncBufRead, AsyncBufReadExt};
 
+use crate::errors::{Error, Result, SyntaxError};
 use crate::events::Event;
 use crate::name::{QName, ResolveResult};
 use crate::reader::buffered_reader::impl_buffered_source;
 use crate::reader::{
     is_whitespace, BangType, NsReader, ParseState, ReadElementState, Reader, Span,
 };
-use crate::{Error, Result};
 
 /// A struct for read XML asynchronously from an [`AsyncBufRead`].
 ///

src/reader/buffered_reader.rs

@@ -7,7 +7,7 @@ use std::path::Path;
 
 use memchr;
 
-use crate::errors::{Error, Result};
+use crate::errors::{Error, Result, SyntaxError};
 use crate::events::Event;
 use crate::name::QName;
 use crate::reader::{is_whitespace, BangType, ReadElementState, Reader, Span, XmlSource};
@@ -54,7 +54,7 @@ macro_rules! impl_buffered_source {
             byte: u8,
             buf: &'b mut Vec<u8>,
             position: &mut usize,
-        ) -> Result<Option<&'b [u8]>> {
+        ) -> Result<(&'b [u8], bool)> {
             // search byte must be within the ascii range
             debug_assert!(byte.is_ascii());
 
@@ -90,18 +90,14 @@ macro_rules! impl_buffered_source {
             }
             *position += read;
 
-            if read == 0 {
-                Ok(None)
-            } else {
-                Ok(Some(&buf[start..]))
-            }
+            Ok((&buf[start..], done))
         }
 
         $($async)? fn read_bang_element $(<$lf>)? (
             &mut self,
             buf: &'b mut Vec<u8>,
             position: &mut usize,
-        ) -> Result<Option<(BangType, &'b [u8])>> {
+        ) -> Result<(BangType, &'b [u8])> {
             // Peeked one bang ('!') before being called, so it's guaranteed to
             // start with it.
             let start = buf.len();
@@ -115,7 +111,7 @@ macro_rules! impl_buffered_source {
                 match self $(.$reader)? .fill_buf() $(.$await)? {
                     // Note: Do not update position, so the error points to
                     // somewhere sane rather than at the EOF
-                    Ok(n) if n.is_empty() => return Err(bang_type.to_err()),
+                    Ok(n) if n.is_empty() => break,
                     Ok(available) => {
                         // We only parse from start because we don't want to consider
                         // whatever is in the buffer before the bang element
@@ -126,7 +122,7 @@ macro_rules! impl_buffered_source {
                             read += used;
 
                             *position += read;
-                            break;
+                            return Ok((bang_type, &buf[start..]));
                         } else {
                             buf.extend_from_slice(available);
 
@@ -143,19 +139,15 @@ macro_rules! impl_buffered_source {
                 }
             }
 
-            if read == 0 {
-                Ok(None)
-            } else {
-                Ok(Some((bang_type, &buf[start..])))
-            }
+            Err(bang_type.to_err())
         }
 
         #[inline]
         $($async)? fn read_element $(<$lf>)? (
             &mut self,
             buf: &'b mut Vec<u8>,
             position: &mut usize,
-        ) -> Result<Option<&'b [u8]>> {
+        ) -> Result<&'b [u8]> {
             let mut state = ReadElementState::Elem;
             let mut read = 0;
 
@@ -172,7 +164,7 @@ macro_rules! impl_buffered_source {
 
                             // Position now just after the `>` symbol
                             *position += read;
-                            break;
+                            return Ok(&buf[start..]);
                         } else {
                             // The `>` symbol not yet found, continue reading
                             buf.extend_from_slice(available);
@@ -190,11 +182,7 @@ macro_rules! impl_buffered_source {
                 };
             }
 
-            if read == 0 {
-                Ok(None)
-            } else {
-                Ok(Some(&buf[start..]))
-            }
+            Err(Error::Syntax(SyntaxError::UnclosedTag))
         }
 
         $($async)? fn skip_whitespace(&mut self, position: &mut usize) -> Result<()> {