Output error when ls into a file without permission (#3218)

* Output error when ls into a file without permission

* added test to check fails when ls into prohibited dir

* fix lint

* trigger wasm build

* Update filesystem_shell.rs

Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>

crates/nu-command/tests/commands/ls.rs

@@ -244,6 +244,27 @@ fn lists_all_hidden_files_when_glob_does_not_contain_dot() {
     })
 }
 
+#[test]
+#[cfg(unix)]
+fn fails_with_ls_to_dir_without_permission() {
+    Playground::setup("ls_test_1", |dirs, sandbox| {
+        sandbox.within("dir_a").with_files(vec![
+            EmptyFile("yehuda.11.txt"),
+            EmptyFile("jonathan.10.txt"),
+        ]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                chmod 000 dir_a; ls dir_a
+            "#
+        ));
+        assert!(actual
+            .err
+            .contains("The permissions of 0 do not allow access for this user"));
+    })
+}
+
 #[test]
 fn lists_files_including_starting_with_dot() {
     Playground::setup("ls_test_9", |dirs, sandbox| {

crates/nu-engine/src/filesystem/filesystem_shell.rs

@@ -125,6 +125,26 @@ impl Shell for FilesystemShell {
                 let p_tag = p.tag;
                 let mut p = p.item;
                 if p.is_dir() {
+                    if permission_denied(&p) {
+                        #[cfg(unix)]
+                        let error_msg = format!(
+                            "The permissions of {:o} do not allow access for this user",
+                            p.metadata()
+                                .expect(
+                                    "this shouldn't be called since we already know there is a dir"
+                                )
+                                .permissions()
+                                .mode()
+                                & 0o0777
+                        );
+                        #[cfg(not(unix))]
+                        let error_msg = String::from("Permission denied");
+                        return Err(ShellError::labeled_error(
+                            "Permission denied",
+                            error_msg,
+                            &p_tag,
+                        ));
+                    }
                     if is_empty_dir(&p) {
                         return Ok(OutputStream::empty());
                     }
@@ -915,6 +935,13 @@ fn is_empty_dir(dir: impl AsRef<Path>) -> bool {
     }
 }
 
+fn permission_denied(dir: impl AsRef<Path>) -> bool {
+    match dir.as_ref().read_dir() {
+        Err(e) => matches!(e.kind(), std::io::ErrorKind::PermissionDenied),
+        Ok(_) => false,
+    }
+}
+
 fn is_hidden_dir(dir: impl AsRef<Path>) -> bool {
     #[cfg(windows)]
     {