mv: symlink exponential walk fix

src/uu/mv/src/hardlink.rs

@@ -215,18 +215,16 @@ impl HardlinkGroupScanner {
     fn scan_single_path(&mut self, path: &Path) -> io::Result<()> {
         use std::os::unix::fs::MetadataExt;
 
-        if path.is_dir() {
+        let metadata = path.symlink_metadata()?;
+        if metadata.is_dir() {
             // Recursively scan directory contents
             self.scan_directory_recursive(path)?;
-        } else {
-            let metadata = path.symlink_metadata()?;
-            if metadata.is_file() && metadata.nlink() > 1 {
-                let key = (metadata.dev(), metadata.ino());
-                self.hardlink_groups
-                    .entry(key)
-                    .or_default()
-                    .push(path.to_path_buf());
-            }
+        } else if metadata.is_file() && metadata.nlink() > 1 {
+            let key = (metadata.dev(), metadata.ino());
+            self.hardlink_groups
+                .entry(key)
+                .or_default()
+                .push(path.to_path_buf());
         }
         Ok(())
     }
@@ -238,15 +236,17 @@ impl HardlinkGroupScanner {
         let entries = std::fs::read_dir(dir)?;
         for entry in entries {
             let entry = entry?;
-            let path = entry.path();
 
-            if path.is_dir() {
-                self.scan_directory_recursive(&path)?;
+            if entry.file_type()?.is_dir() {
+                self.scan_directory_recursive(&entry.path())?;
             } else {
-                let metadata = path.symlink_metadata()?;
+                let metadata = entry.metadata()?;
                 if metadata.is_file() && metadata.nlink() > 1 {
                     let key = (metadata.dev(), metadata.ino());
-                    self.hardlink_groups.entry(key).or_default().push(path);
+                    self.hardlink_groups
+                        .entry(key)
+                        .or_default()
+                        .push(entry.path());
                 }
             }
         }

tests/by-util/test_mv.rs

@@ -1988,6 +1988,28 @@ fn test_move_should_not_fallback_to_copy() {
     assert!(!at.file_exists(target_file));
 }
 
+// A directory containing two symlinks that point back at an ancestor must not
+// send the hardlink pre-scan into an exponential walk.
+#[test]
+#[cfg(unix)]
+fn test_mv_dir_with_symlink_cycles_terminates() {
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    at.mkdir("dir");
+    at.mkdir("dest");
+    at.write("dir/file", "content");
+    at.relative_symlink_dir(".", "dir/loop1");
+    at.relative_symlink_dir(".", "dir/loop2");
+
+    ucmd.arg("dir").arg("dest/").succeeds().no_output();
+
+    assert!(at.dir_exists("dest/dir"));
+    assert_eq!(at.read("dest/dir/file"), "content");
+    assert!(at.is_symlink("dest/dir/loop1"));
+    assert!(at.is_symlink("dest/dir/loop2"));
+    assert!(!at.dir_exists("dir"));
+}
+
 // Todo:
 
 // $ at.touch a b