du: fix double-counting hard links across multiple arguments

src/uu/du/src/du.rs

@@ -1080,6 +1080,9 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     let (print_tx, rx) = mpsc::channel::<UResult<StatPrintInfo>>();
     let printing_thread = thread::spawn(move || stat_printer.print_stats(&rx));
 
+    // Track seen inodes across all arguments to avoid double-counting hard links
+    let mut seen_inodes: HashSet<FileInfo> = HashSet::new();
+
     'loop_file: for path in files {
         // Skip if we don't want to ignore anything
         if !&traversal_options.excludes.is_empty() {
@@ -1098,9 +1101,6 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
             }
         }
 
-        // Check existence of path provided in argument
-        let mut seen_inodes: HashSet<FileInfo> = HashSet::new();
-
         // Determine which traversal method to use
         #[cfg(all(unix, not(target_os = "redox")))]
         let use_safe_traversal = traversal_options.dereference != Deref::All;

tests/by-util/test_du.rs

@@ -532,6 +532,22 @@ fn du_hard_link(s: &str) {
     }
 }
 
+#[cfg(all(unix, not(target_os = "android")))]
+#[test]
+fn test_du_hard_link_multiple_args() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.mkdir("dir1");
+    at.mkdir("dir2");
+    at.write("dir1/file", &"x".repeat(10000));
+    at.hard_link("dir1/file", "dir2/file");
+
+    let result = ucmd.args(&["-b", "dir1", "dir2"]).succeeds();
+    let lines: Vec<&str> = result.stdout_str().lines().collect();
+    let size = |i: usize| lines[i].split('\t').next().unwrap().parse::<u64>().unwrap();
+    assert!(size(0) >= 10000);
+    assert!(size(1) < 1000);
+}
+
 #[test]
 #[cfg(not(target_os = "openbsd"))]
 fn test_du_d_flag() {