change!: fall back to the raw text when ansi-c unquoting fails

gix-attributes/src/parse.rs

@@ -26,8 +26,6 @@ mod error {
         AttributeName { line_number: usize, attribute: BString },
         #[error("Macro in line {line_number} has an invalid name: {macro_name}")]
         MacroName { line_number: usize, macro_name: BString },
-        #[error("Could not unquote attributes line")]
-        Unquote(#[from] gix_quote::ansi_c::undo::Error),
     }
 }
 pub use error::Error;
@@ -122,16 +120,16 @@ fn parse_line(line: &BStr, line_number: usize) -> Option<Result<(Kind, Iter<'_>,
         return None;
     }
 
-    let (line, attrs): (Cow<'_, _>, _) = if line.starts_with(b"\"") {
-        let (unquoted, consumed) = match gix_quote::ansi_c::undo(line) {
-            Ok(res) => res,
-            Err(err) => return Some(Err(err.into())),
-        };
-        (unquoted, &line[consumed..])
-    } else {
-        line.find_byteset(BLANKS)
+    let unquoted = line
+        .starts_with(b"\"")
+        .then(|| gix_quote::ansi_c::undo(line).ok())
+        .flatten();
+    let (line, attrs): (Cow<'_, _>, _) = match unquoted {
+        Some((unquoted, consumed)) => (unquoted, &line[consumed..]),
+        None => line
+            .find_byteset(BLANKS)
             .map(|pos| (line[..pos].as_bstr().into(), line[pos..].as_bstr()))
-            .unwrap_or((line.into(), [].as_bstr()))
+            .unwrap_or((line.into(), [].as_bstr())),
     };
 
     let kind_res = match line.strip_prefix(b"[attr]").filter(|name| !name.is_empty()) {

gix-attributes/tests/attributes/parse.rs

@@ -115,9 +115,23 @@ fn exclamation_marks_must_be_escaped_or_error_unlike_gitignore() {
 }
 
 #[test]
-fn invalid_escapes_in_quotes_are_an_error() {
-    assert!(matches!(try_line(r#""\!hello""#), Err(parse::Error::Unquote(_))));
-    assert!(lenient_lines(r#""\!hello""#).is_empty());
+fn broken_quoting_falls_back_to_the_raw_text() {
+    assert_eq!(
+        line(r#""\!hello""#),
+        (pattern(r#""\!hello""#, Mode::NO_SUB_DIR, Some(1)), vec![], 1),
+        "an invalid escape leaves the quotes in place, so the leading `!` no longer negates, \
+         and the backslash goes on to escape it for the matcher"
+    );
+    assert_eq!(
+        line(r#""abc"#),
+        (pattern(r#""abc"#, Mode::NO_SUB_DIR, None), vec![], 1),
+        "so does a quote that is never closed"
+    );
+    assert_eq!(
+        line(r#""abc def"#),
+        (pattern(r#""abc"#, Mode::NO_SUB_DIR, None), vec![set("def")], 1),
+        "the raw text is then split on blanks like any unquoted pattern"
+    );
 }
 
 #[test]

gix-odb/src/alternate/mod.rs

@@ -22,6 +22,7 @@ use gix_path::realpath::MAX_SYMLINKS;
 
 ///
 pub mod parse;
+pub use parse::function::parse;
 
 /// Returned by [`resolve()`]
 #[derive(thiserror::Error, Debug)]
@@ -67,7 +68,7 @@ pub fn resolve(objects_directory: PathBuf, current_dir: &std::path::Path) -> Res
         seen.push((dir_canonicalized, parent_idx));
         match fs::read(dir.join("info").join("alternates")) {
             Ok(input) => {
-                for path in parse::content(&input)?.into_iter().rev() {
+                for path in parse(&input)?.into_iter().rev() {
                     dirs.push((Some(idx), objects_directory.join(path)));
                 }
             }

gix-odb/src/alternate/parse.rs

@@ -1,33 +1,51 @@
-use std::{borrow::Cow, path::PathBuf};
-
-use gix_object::bstr::ByteSlice;
-
 /// Returned as part of [`crate::alternate::Error::Parse`]
 #[derive(thiserror::Error, Debug)]
 #[expect(missing_docs)]
 pub enum Error {
     #[error("Could not obtain an object path for the alternate directory '{}'", String::from_utf8_lossy(.0))]
     PathConversion(Vec<u8>),
-    #[error("Could not unquote alternate path")]
-    Unquote(#[from] gix_quote::ansi_c::undo::Error),
 }
 
-pub(crate) fn content(input: &[u8]) -> Result<Vec<PathBuf>, Error> {
-    let mut out = Vec::new();
-    for line in input.split(|b| *b == b'\n') {
-        let line = line.as_bstr();
-        if line.is_empty() || line.starts_with(b"#") {
-            continue;
-        }
-        out.push(
-            gix_path::try_from_bstr(if line.starts_with(b"\"") {
-                gix_quote::ansi_c::undo(line)?.0
+pub(super) mod function {
+    use super::Error;
+    use std::{borrow::Cow, path::PathBuf};
+
+    use gix_object::bstr::ByteSlice;
+
+    /// Parse the raw contents of an `objects/info/alternates` file from `input` into paths.
+    ///
+    /// Empty entries and comments are ignored. Entries beginning with `"` use Git's C-style quoting,
+    /// which permits literal newlines in paths. Invalid quoting falls back to the raw entry.
+    pub fn parse(mut input: &[u8]) -> Result<Vec<PathBuf>, Error> {
+        let mut out = Vec::new();
+        while !input.is_empty() {
+            let entry = input.as_bstr();
+            let end_of_line = || entry.find_byte(b'\n').unwrap_or(entry.len());
+            let (path, consumed) = if entry.starts_with(b"#") {
+                (None, end_of_line())
             } else {
-                Cow::Borrowed(line)
-            })
-            .map_err(|_| Error::PathConversion(line.to_vec()))?
-            .into_owned(),
-        );
+                // Like Git, try unquoting before treating a newline as the next separator.
+                match entry.starts_with(b"\"").then(|| gix_quote::ansi_c::undo(entry)) {
+                    Some(Ok((unquoted, consumed))) => (Some(unquoted), consumed),
+                    _ => {
+                        let consumed = end_of_line();
+                        (Some(Cow::Borrowed(entry[..consumed].as_bstr())), consumed)
+                    }
+                }
+            };
+            let original = &entry[..consumed];
+            let maybe_nl = usize::from(consumed < input.len());
+            input = &input[consumed + maybe_nl..];
+
+            let Some(path) = path.filter(|path| !path.is_empty()) else {
+                continue;
+            };
+            out.push(
+                gix_path::try_from_bstr(path)
+                    .map_err(|_| Error::PathConversion(original.to_vec()))?
+                    .into_owned(),
+            );
+        }
+        Ok(out)
     }
-    Ok(out)
 }

gix-odb/tests/odb/alternate.rs

@@ -5,6 +5,37 @@ use std::{
 
 use gix_odb::alternate;
 
+mod parse {
+    use std::path::PathBuf;
+
+    use gix_odb::alternate;
+
+    #[test]
+    fn a_quote_that_is_never_closed_is_used_as_a_literal_path() {
+        assert_eq!(
+            alternate::parse(br#""unterminated"#).expect("no path conversion issue"),
+            vec![PathBuf::from(r#""unterminated"#)],
+            "broken quoting falls back to the raw line"
+        );
+    }
+
+    #[test]
+    fn a_properly_quoted_path_is_unquoted() {
+        assert_eq!(
+            alternate::parse(br#""quoted\tpath""#).expect("no path conversion issue"),
+            vec![PathBuf::from("quoted\tpath")]
+        );
+    }
+
+    #[test]
+    fn a_quoted_path_may_contain_the_line_separator() {
+        assert_eq!(
+            alternate::parse(b"\"quoted\npath\"\nnext").expect("no path conversion issue"),
+            vec![PathBuf::from("quoted\npath"), PathBuf::from("next")],
+            "Git looks for a closing quote before treating a newline as the next separator"
+        );
+    }
+}
 pub fn alternate(
     objects_at: impl Into<PathBuf>,
     objects_to: impl Into<PathBuf>,

gix-quote/src/ansi_c.rs

@@ -15,6 +15,7 @@ use gix_error::{ErrorExt, OptionExt, ResultExt, ValidationError};
 /// quotation, otherwise a new unquoted string will always be allocated.
 /// The amount of consumed bytes allow to pass strings that start with a quote, and skip all quoted text for additional processing
 ///
+/// A quote that is never closed is an error.
 /// See [the tests][tests] for quotation examples.
 ///
 /// [tests]: https://github.com/GitoxideLabs/gitoxide/blob/64872690e60efdd9267d517f4d9971eecd3b875c/gix-quote/tests/quote.rs#L57-L74
@@ -93,9 +94,9 @@ pub fn undo(input: &BStr) -> Result<(Cow<'_, BStr>, usize), undo::Error> {
                 }
             }
             None => {
-                out.extend_from_slice(input);
-                consumed += input.len();
-                break;
+                return Err(
+                    ValidationError::new_with_input("Missing closing quote in quoted string", original).raise(),
+                );
             }
         }
     }

gix-quote/tests/quote.rs

@@ -81,6 +81,16 @@ mod ansi_c {
             assert_eq!(&input[consumed..], " out of quote");
         }
 
+        #[test]
+        fn a_quote_that_is_never_closed_is_an_error() {
+            for unterminated in [r#"""#, r#""abc"#, r#""abc def"#, r#""abc\"#, r#""\""#] {
+                assert!(
+                    ansi_c::undo(unterminated.into()).is_err(),
+                    "{unterminated:?} should not parse"
+                );
+            }
+        }
+
         #[test]
         fn fuzzed() {
             for invalid in ["\"\\", "\"Q\u{2}QT\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\0\0\\"] {