rust: Reject empty name

Corresponding to the C change.

Signed-off-by: Colin Walters <[email protected]>

rust/composefs/src/dumpfile.rs

@@ -163,7 +163,13 @@ fn unescape_to_osstr(s: &str) -> Result<Cow<OsStr>> {
 /// Unescape a string into a Rust `Path` which is really just an alias for a byte array,
 /// although there is an implicit assumption that there are no embedded `NUL` bytes.
 fn unescape_to_path(s: &str) -> Result<Cow<Path>> {
-    let r = match unescape_to_osstr(s)? {
+    let v = unescape_to_osstr(s).and_then(|v| {
+        if v.is_empty() {
+            anyhow::bail!("Invalid empty path");
+        }
+        Ok(v)
+    })?;
+    let r = match v {
         Cow::Borrowed(v) => Cow::Borrowed(Path::new(v)),
         Cow::Owned(v) => Cow::Owned(PathBuf::from(v)),
     };
@@ -255,7 +261,7 @@ impl<'p> Entry<'p> {
     pub fn parse(s: &'p str) -> Result<Entry<'p>> {
         let mut components = s.split(' ');
         let mut next = |name: &str| components.next().ok_or_else(|| anyhow!("Missing {name}"));
-        let path = unescape_to_path(next("path")?)?;
+        let path = unescape_to_path((next("path")?)?;
         let size = u64::from_str(next("size")?)?;
         let modeval = next("mode")?;
         let (is_hardlink, mode) = if let Some((_, rest)) = modeval.split_once('@') {
@@ -484,6 +490,11 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn test_unescape_path() {
+        assert!(unescape_to_path("").is_err());
+    }
+
     #[test]
     fn test_should_fail() {
         const CASES: &[(&str, &str)] = &[