Fixes in unescape routine

Changelog.md

@@ -22,9 +22,24 @@
 - [#773]: Fixed reporting incorrect end position in `Reader::read_to_end` family
   of methods and trimming of the trailing spaces in `Reader::read_text` when
   `trim_text_start` is set and the last event is not a `Text` event.
+- [#771]: Character references now allow any number of leading zeroes as it should.
+  As a result, the following variants of `quick_xml::escape::EscapeError` are removed:
+  - `TooLongDecimal`
+  - `TooLongHexadecimal`
+- [#771]: Fixed `Attribute::unescape_value` which does not unescape predefined values since 0.32.0.
 
 ### Misc Changes
 
+- [#771]: `EscapeError::UnrecognizedSymbol` renamed to `EscapeError::UnrecognizedEntity`.
+- [#771]: Implemented `PartialEq` for `EscapeError`.
+- [#771]: Replace the following variants of `EscapeError` by `InvalidCharRef` variant
+  with a new `ParseCharRefError` inside:
+  - `EntityWithNull`
+  - `InvalidDecimal`
+  - `InvalidHexadecimal`
+  - `InvalidCodepoint`
+
+[#771]: https://github.com/tafia/quick-xml/pull/771
 [#772]: https://github.com/tafia/quick-xml/pull/772
 [#773]: https://github.com/tafia/quick-xml/pull/773
 

src/de/mod.rs

@@ -2135,9 +2135,9 @@ struct XmlReader<'i, R: XmlRead<'i>, E: EntityResolver = PredefinedEntityResolve
     lookahead: Result<PayloadEvent<'i>, DeError>,
 
     /// Used to resolve unknown entities that would otherwise cause the parser
-    /// to return an [`EscapeError::UnrecognizedSymbol`] error.
+    /// to return an [`EscapeError::UnrecognizedEntity`] error.
     ///
-    /// [`EscapeError::UnrecognizedSymbol`]: crate::escape::EscapeError::UnrecognizedSymbol
+    /// [`EscapeError::UnrecognizedEntity`]: crate::escape::EscapeError::UnrecognizedEntity
     entity_resolver: E,
 }
 

src/de/resolver.rs

@@ -81,10 +81,10 @@ pub trait EntityResolver {
     /// Called when an entity needs to be resolved.
     ///
     /// `None` is returned if a suitable value can not be found.
-    /// In that case an [`EscapeError::UnrecognizedSymbol`] will be returned by
+    /// In that case an [`EscapeError::UnrecognizedEntity`] will be returned by
     /// a deserializer.
     ///
-    /// [`EscapeError::UnrecognizedSymbol`]: crate::escape::EscapeError::UnrecognizedSymbol
+    /// [`EscapeError::UnrecognizedEntity`]: crate::escape::EscapeError::UnrecognizedEntity
     fn resolve(&self, entity: &str) -> Option<&str>;
 }
 

src/encoding.rs

@@ -99,6 +99,15 @@ impl Decoder {
 
         Ok(())
     }
+
+    /// Decodes the `Cow` buffer, preserves the lifetime
+    pub(crate) fn decode_cow<'b>(&self, bytes: &Cow<'b, [u8]>) -> Result<Cow<'b, str>> {
+        match bytes {
+            Cow::Borrowed(bytes) => self.decode(bytes),
+            // Convert to owned, because otherwise Cow will be bound with wrong lifetime
+            Cow::Owned(bytes) => Ok(self.decode(bytes)?.into_owned().into()),
+        }
+    }
 }
 
 /// Decodes the provided bytes using the specified encoding.

src/escape.rs

@@ -2,62 +2,82 @@
 
 use memchr::memchr2_iter;
 use std::borrow::Cow;
+use std::num::ParseIntError;
 use std::ops::Range;
 
-#[cfg(test)]
-use pretty_assertions::assert_eq;
+/// Error of parsing character reference (`&#<dec-number>;` or `&#x<hex-number>;`).
+#[derive(Clone, Debug, PartialEq)]
+pub enum ParseCharRefError {
+    /// Number contains sign character (`+` or `-`) which is not allowed.
+    UnexpectedSign,
+    /// Number cannot be parsed due to non-number characters or a numeric overflow.
+    InvalidNumber(ParseIntError),
+    /// Character reference represents not a valid unicode codepoint.
+    InvalidCodepoint(u32),
+    /// Character reference expanded to a not permitted character for an XML.
+    ///
+    /// Currently, only `0x0` character produces this error.
+    IllegalCharacter(u32),
+}
+
+impl std::fmt::Display for ParseCharRefError {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self {
+            Self::UnexpectedSign => f.write_str("unexpected number sign"),
+            Self::InvalidNumber(e) => e.fmt(f),
+            Self::InvalidCodepoint(n) => write!(f, "`{}` is not a valid codepoint", n),
+            Self::IllegalCharacter(n) => write!(f, "0x{:x} character is not permitted in XML", n),
+        }
+    }
+}
+
+impl std::error::Error for ParseCharRefError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::InvalidNumber(e) => Some(e),
+            _ => None,
+        }
+    }
+}
 
 /// Error for XML escape / unescape.
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub enum EscapeError {
-    /// Entity with Null character
-    EntityWithNull(Range<usize>),
-    /// Unrecognized escape symbol
-    UnrecognizedSymbol(Range<usize>, String),
+    /// Referenced entity in unknown to the parser.
+    UnrecognizedEntity(Range<usize>, String),
     /// Cannot find `;` after `&`
     UnterminatedEntity(Range<usize>),
-    /// Cannot convert Hexa to utf8
-    TooLongHexadecimal,
-    /// Character is not a valid hexadecimal value
-    InvalidHexadecimal(char),
-    /// Cannot convert decimal to hexa
-    TooLongDecimal,
-    /// Character is not a valid decimal value
-    InvalidDecimal(char),
-    /// Not a valid unicode codepoint
-    InvalidCodepoint(u32),
+    /// Attempt to parse character reference (`&#<dec-number>;` or `&#x<hex-number>;`)
+    /// was unsuccessful, not all characters are decimal or hexadecimal numbers.
+    InvalidCharRef(ParseCharRefError),
 }
 
 impl std::fmt::Display for EscapeError {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         match self {
-            EscapeError::EntityWithNull(e) => write!(
-                f,
-                "Error while escaping character at range {:?}: Null character entity not allowed",
-                e
-            ),
-            EscapeError::UnrecognizedSymbol(rge, res) => write!(
-                f,
-                "Error while escaping character at range {:?}: Unrecognized escape symbol: {:?}",
-                rge, res
-            ),
+            EscapeError::UnrecognizedEntity(rge, res) => {
+                write!(f, "at {:?}: unrecognized entity `{}`", rge, res)
+            }
             EscapeError::UnterminatedEntity(e) => write!(
                 f,
                 "Error while escaping character at range {:?}: Cannot find ';' after '&'",
                 e
             ),
-            EscapeError::TooLongHexadecimal => write!(f, "Cannot convert hexadecimal to utf8"),
-            EscapeError::InvalidHexadecimal(e) => {
-                write!(f, "'{}' is not a valid hexadecimal character", e)
+            EscapeError::InvalidCharRef(e) => {
+                write!(f, "invalid character reference: {}", e)
             }
-            EscapeError::TooLongDecimal => write!(f, "Cannot convert decimal to utf8"),
-            EscapeError::InvalidDecimal(e) => write!(f, "'{}' is not a valid decimal character", e),
-            EscapeError::InvalidCodepoint(n) => write!(f, "'{}' is not a valid codepoint", n),
         }
     }
 }
 
-impl std::error::Error for EscapeError {}
+impl std::error::Error for EscapeError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::InvalidCharRef(e) => Some(e),
+            _ => None,
+        }
+    }
+}
 
 /// Escapes an `&str` and replaces all xml special characters (`<`, `>`, `&`, `'`, `"`)
 /// with their corresponding xml escaped value.
@@ -251,12 +271,12 @@ where
                 // search for character correctness
                 let pat = &raw[start + 1..end];
                 if let Some(entity) = pat.strip_prefix('#') {
-                    let codepoint = parse_number(entity, start..end)?;
+                    let codepoint = parse_number(entity).map_err(EscapeError::InvalidCharRef)?;
                     unescaped.push_str(codepoint.encode_utf8(&mut [0u8; 4]));
                 } else if let Some(value) = resolve_entity(pat) {
                     unescaped.push_str(value);
                 } else {
-                    return Err(EscapeError::UnrecognizedSymbol(
+                    return Err(EscapeError::UnrecognizedEntity(
                         start + 1..end,
                         pat.to_string(),
                     ));
@@ -1796,141 +1816,27 @@ pub const fn resolve_html5_entity(entity: &str) -> Option<&'static str> {
     Some(s)
 }
 
-fn parse_number(bytes: &str, range: Range<usize>) -> Result<char, EscapeError> {
-    let code = if let Some(hex_digits) = bytes.strip_prefix('x') {
-        parse_hexadecimal(hex_digits)
+fn parse_number(num: &str) -> Result<char, ParseCharRefError> {
+    let code = if let Some(hex) = num.strip_prefix('x') {
+        from_str_radix(hex, 16)?
     } else {
-        parse_decimal(bytes)
-    }?;
+        from_str_radix(num, 10)?
+    };
     if code == 0 {
-        return Err(EscapeError::EntityWithNull(range));
+        return Err(ParseCharRefError::IllegalCharacter(code));
     }
     match std::char::from_u32(code) {
         Some(c) => Ok(c),
-        None => Err(EscapeError::InvalidCodepoint(code)),
-    }
-}
-
-fn parse_hexadecimal(bytes: &str) -> Result<u32, EscapeError> {
-    // maximum code is 0x10FFFF => 6 characters
-    if bytes.len() > 6 {
-        return Err(EscapeError::TooLongHexadecimal);
-    }
-    let mut code = 0;
-    for b in bytes.bytes() {
-        code <<= 4;
-        code += match b {
-            b'0'..=b'9' => b - b'0',
-            b'a'..=b'f' => b - b'a' + 10,
-            b'A'..=b'F' => b - b'A' + 10,
-            b => return Err(EscapeError::InvalidHexadecimal(b as char)),
-        } as u32;
+        None => Err(ParseCharRefError::InvalidCodepoint(code)),
     }
-    Ok(code)
 }
 
-fn parse_decimal(bytes: &str) -> Result<u32, EscapeError> {
-    // maximum code is 0x10FFFF = 1114111 => 7 characters
-    if bytes.len() > 7 {
-        return Err(EscapeError::TooLongDecimal);
-    }
-    let mut code = 0;
-    for b in bytes.bytes() {
-        code *= 10;
-        code += match b {
-            b'0'..=b'9' => b - b'0',
-            b => return Err(EscapeError::InvalidDecimal(b as char)),
-        } as u32;
+#[inline]
+fn from_str_radix(src: &str, radix: u32) -> Result<u32, ParseCharRefError> {
+    match src.as_bytes().first().copied() {
+        // We should not allow sign numbers, but u32::from_str_radix will accept `+`.
+        // We also handle `-` to be consistent in returned errors
+        Some(b'+') | Some(b'-') => Err(ParseCharRefError::UnexpectedSign),
+        _ => u32::from_str_radix(src, radix).map_err(ParseCharRefError::InvalidNumber),
     }
-    Ok(code)
-}
-
-#[test]
-fn test_unescape() {
-    let unchanged = unescape("test").unwrap();
-    // assert_eq does not check that Cow is borrowed, but we explicitly use Cow
-    // because it influences diff
-    // TODO: use assert_matches! when stabilized and other features will bump MSRV
-    assert_eq!(unchanged, Cow::Borrowed("test"));
-    assert!(matches!(unchanged, Cow::Borrowed(_)));
-
-    assert_eq!(
-        unescape("&lt;&amp;test&apos;&quot;&gt;").unwrap(),
-        "<&test'\">"
-    );
-    assert_eq!(unescape("&#x30;").unwrap(), "0");
-    assert_eq!(unescape("&#48;").unwrap(), "0");
-    assert!(unescape("&foo;").is_err());
-}
-
-#[test]
-fn test_unescape_with() {
-    let custom_entities = |ent: &str| match ent {
-        "foo" => Some("BAR"),
-        _ => None,
-    };
-
-    let unchanged = unescape_with("test", custom_entities).unwrap();
-    // assert_eq does not check that Cow is borrowed, but we explicitly use Cow
-    // because it influences diff
-    // TODO: use assert_matches! when stabilized and other features will bump MSRV
-    assert_eq!(unchanged, Cow::Borrowed("test"));
-    assert!(matches!(unchanged, Cow::Borrowed(_)));
-
-    assert!(unescape_with("&lt;", custom_entities).is_err());
-    assert_eq!(unescape_with("&#x30;", custom_entities).unwrap(), "0");
-    assert_eq!(unescape_with("&#48;", custom_entities).unwrap(), "0");
-    assert_eq!(unescape_with("&foo;", custom_entities).unwrap(), "BAR");
-    assert!(unescape_with("&fop;", custom_entities).is_err());
-}
-
-#[test]
-fn test_escape() {
-    let unchanged = escape("test");
-    // assert_eq does not check that Cow is borrowed, but we explicitly use Cow
-    // because it influences diff
-    // TODO: use assert_matches! when stabilized and other features will bump MSRV
-    assert_eq!(unchanged, Cow::Borrowed("test"));
-    assert!(matches!(unchanged, Cow::Borrowed(_)));
-
-    assert_eq!(escape("<&\"'>"), "&lt;&amp;&quot;&apos;&gt;");
-    assert_eq!(escape("<test>"), "&lt;test&gt;");
-    assert_eq!(escape("\"a\"bc"), "&quot;a&quot;bc");
-    assert_eq!(escape("\"a\"b&c"), "&quot;a&quot;b&amp;c");
-    assert_eq!(
-        escape("prefix_\"a\"b&<>c"),
-        "prefix_&quot;a&quot;b&amp;&lt;&gt;c"
-    );
-}
-
-#[test]
-fn test_partial_escape() {
-    let unchanged = partial_escape("test");
-    // assert_eq does not check that Cow is borrowed, but we explicitly use Cow
-    // because it influences diff
-    // TODO: use assert_matches! when stabilized and other features will bump MSRV
-    assert_eq!(unchanged, Cow::Borrowed("test"));
-    assert!(matches!(unchanged, Cow::Borrowed(_)));
-
-    assert_eq!(partial_escape("<&\"'>"), "&lt;&amp;\"'&gt;");
-    assert_eq!(partial_escape("<test>"), "&lt;test&gt;");
-    assert_eq!(partial_escape("\"a\"bc"), "\"a\"bc");
-    assert_eq!(partial_escape("\"a\"b&c"), "\"a\"b&amp;c");
-    assert_eq!(
-        partial_escape("prefix_\"a\"b&<>c"),
-        "prefix_\"a\"b&amp;&lt;&gt;c"
-    );
-}
-
-#[test]
-fn test_minimal_escape() {
-    assert_eq!(minimal_escape("test"), Cow::Borrowed("test"));
-    assert_eq!(minimal_escape("<&\"'>"), "&lt;&amp;\"'>");
-    assert_eq!(minimal_escape("<test>"), "&lt;test>");
-    assert_eq!(minimal_escape("\"a\"bc"), "\"a\"bc");
-    assert_eq!(minimal_escape("\"a\"b&c"), "\"a\"b&amp;c");
-    assert_eq!(
-        minimal_escape("prefix_\"a\"b&<>c"),
-        "prefix_\"a\"b&amp;&lt;>c"
-    );
 }