chmod: keep operand order with --reference

src/uu/chmod/src/chmod.rs

@@ -177,9 +177,10 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
         .unwrap_or_default();
     let cmode = if fmode.is_some() {
         // "--reference" and MODE are mutually exclusive
-        // if "--reference" was used MODE needs to be interpreted as another FILE
+        // if "--reference" was used MODE needs to be interpreted as another FILE,
+        // it is the first FILE, keep the command-line order
         // it wasn't possible to implement this behavior directly with clap
-        files.push(OsString::from(cmode));
+        files.insert(0, OsString::from(cmode));
         None
     } else {
         Some(cmode)

tests/by-util/test_chmod.rs

@@ -411,6 +411,51 @@ fn test_chmod_reference_file() {
     run_single_test(&tests[0], &at, ucmd);
 }
 
+#[test]
+fn test_chmod_reference_keeps_operand_order() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.touch("ref");
+    at.set_mode("ref", 0o644);
+    for name in ["a", "b", "c"] {
+        at.touch(name);
+        at.set_mode(name, 0o600);
+    }
+
+    ucmd.args(&["-v", "--reference=ref", "a", "b", "c"])
+        .succeeds()
+        .stdout_is(
+            "mode of 'a' changed from 0600 (rw-------) to 0644 (rw-r--r--)\n\
+             mode of 'b' changed from 0600 (rw-------) to 0644 (rw-r--r--)\n\
+             mode of 'c' changed from 0600 (rw-------) to 0644 (rw-r--r--)\n",
+        );
+}
+
+#[test]
+fn test_chmod_reference_first_operand_before_its_parent_dir() {
+    use rustix::process::geteuid;
+
+    // The reference mode drops the search bit of `dir`, so `dir/file` is only
+    // reachable if it is handled first. root ignores directory permissions.
+    if geteuid().is_root() {
+        return;
+    }
+
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.touch("ref");
+    at.set_mode("ref", 0o644);
+    at.mkdir("dir");
+    at.touch("dir/file");
+    at.set_mode("dir/file", 0o600);
+    at.set_mode("dir", 0o755);
+
+    ucmd.args(&["--reference=ref", "dir/file", "dir"])
+        .succeeds();
+
+    assert_eq!(at.metadata("dir").permissions().mode() & 0o7777, 0o644);
+    at.set_mode("dir", 0o755);
+    assert_eq!(at.metadata("dir/file").permissions().mode() & 0o7777, 0o644);
+}
+
 #[test]
 fn test_permission_denied() {
     let scene = TestScenario::new(util_name!());