du: ignore duplicate paths provided by user

src/uu/du/src/du.rs

@@ -605,7 +605,13 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     let excludes = build_exclude_patterns(&matches)?;
 
     let mut grand_total = 0;
+    let mut processed_paths = Vec::with_capacity(files.len());
     'loop_file: for path in files {
+        // filter duplicate paths
+        if processed_paths.contains(&path) {
+            continue 'loop_file;
+        }
+
         // Skip if we don't want to ignore anything
         if !&excludes.is_empty() {
             let path_string = path.to_string_lossy();
@@ -664,6 +670,7 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
                     // path_string.  We add it to the grand total.
                     grand_total += size;
                 }
+                processed_paths.push(path.clone());
             }
         } else {
             show_error!(

tests/by-util/test_du.rs

@@ -126,6 +126,33 @@ fn test_du_basics_bad_name() {
         .stderr_only("du: bad_name: No such file or directory\n");
 }
 
+#[test]
+fn test_du_basics_duplicate_bad_name() {
+    let bad_name = "bad_name";
+
+    new_ucmd!()
+        .arg(bad_name)
+        .arg(bad_name)
+        .fails()
+        .stderr_only(concat!(
+            "du: bad_name: No such file or directory\n",
+            "du: bad_name: No such file or directory\n"
+        ));
+}
+
+#[test]
+fn test_du_basics_duplicate_name() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let filename = "a";
+
+    at.touch(filename);
+
+    ucmd.arg(filename)
+        .arg(filename)
+        .succeeds()
+        .stdout_is(format!("0\t{filename}\n"));
+}
+
 #[test]
 fn test_du_soft_link() {
     let ts = TestScenario::new(util_name!());