make parsing sl status output more strict

Summary: Make parsing more strict about format

Reviewed By: JakobDegen

Differential Revision: D68159083

fbshipit-source-id: a97f8ef180b32e13e0338a41aea0f7f465108ec0

app/buck2_file_watcher/src/edenfs/sapling.rs

@@ -133,16 +133,14 @@ pub(crate) async fn get_status<D: AsRef<Path>, F: AsRef<str>, S: AsRef<str>>(
 //   Paths can have spaces, but are not quoted.
 fn process_one_status_line(line: &str) -> buck2_error::Result<Option<(SaplingStatus, String)>> {
     // Must include a status and at least one char path.
-    if line.len() >= 3 {
-        let mut chars = line.chars();
-        let change = chars.next().unwrap();
-        let path = chars.skip(1).collect::<String>();
+    let mut parts = line.split_whitespace();
+    if let (Some(change), Some(path), None) = (parts.next(), parts.next(), parts.next()) {
         Ok(match change {
-            'M' => Some((SaplingStatus::Modified, path)),
-            'A' => Some((SaplingStatus::Added, path)),
-            'R' => Some((SaplingStatus::Removed, path)),
-            '!' => Some((SaplingStatus::Missing, path)),
-            '?' => Some((SaplingStatus::NotTracked, path)),
+            "M" => Some((SaplingStatus::Modified, path.to_owned())),
+            "A" => Some((SaplingStatus::Added, path.to_owned())),
+            "R" => Some((SaplingStatus::Removed, path.to_owned())),
+            "!" => Some((SaplingStatus::Missing, path.to_owned())),
+            "?" => Some((SaplingStatus::NotTracked, path.to_owned())),
             _ => None, // Skip all others
         })
     } else {
@@ -206,6 +204,11 @@ mod tests {
 
         assert!(process_one_status_line("NO").is_err());
 
+        assert!(
+            process_one_status_line("M:buck2/app/buck2_file_watcher/src/edenfs/sapling.rs")
+                .is_err()
+        );
+
         Ok(())
     }
 }