ls: On Windows don't display files hidden by NTFS (#1662)

This little check, allows us to hide the files that
shouldn't be shown on the listing on Windows operating
systems.

Just like the "dot" in UNIX based operating systems
Windows uses its own file attributes to determine if a file
is hidden or not.

The lack of support for this option is normally an annoyance
for many users, this commit adds full support for this feature

src/uu/ls/src/ls.rs

@@ -255,6 +255,18 @@ fn sort_entries(entries: &mut Vec<PathBuf>, options: &getopts::Matches) {
     }
 }
 
+#[cfg(windows)]
+fn is_hidden(file_path: &DirEntry) -> std::io::Result<bool> {
+    let metadata = fs::metadata(file_path.path())?;
+    let attr = metadata.file_attributes();
+    Ok(((attr & 0x2) > 0) || file_path.file_name().to_string_lossy().starts_with('.'))
+}
+
+#[cfg(unix)]
+fn is_hidden(file_path: &DirEntry) -> std::io::Result<bool> {
+    Ok(file_path.file_name().to_string_lossy().starts_with('.'))
+}
+
 #[cfg(windows)]
 fn sort_entries(entries: &mut Vec<PathBuf>, options: &getopts::Matches) {
     let mut reverse = options.opt_present("r");
@@ -286,7 +298,7 @@ fn sort_entries(entries: &mut Vec<PathBuf>, options: &getopts::Matches) {
 fn should_display(entry: &DirEntry, options: &getopts::Matches) -> bool {
     let ffi_name = entry.file_name();
     let name = ffi_name.to_string_lossy();
-    if !options.opt_present("a") && !options.opt_present("A") && name.starts_with('.') {
+    if !options.opt_present("a") && !options.opt_present("A") && is_hidden(entry).unwrap() {
         return false;
     }
     if options.opt_present("B") && name.ends_with('~') {

tests/by-util/test_ls.rs

@@ -310,3 +310,29 @@ fn test_ls_human() {
     assert!(result.success);
     assert!(result.stdout.contains("1.02M"));
 }
+
+#[cfg(windows)]
+#[test]
+fn test_ls_hidden_windows() {
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+    let file = "hiddenWindowsFileNoDot";
+    at.touch(file);
+    // hide the file
+    scene
+        .cmd("attrib")
+        .arg("+h")
+        .arg("+S")
+        .arg("+r")
+        .arg(file)
+        .run();
+    let result = scene.ucmd().run();
+    println!("stderr = {:?}", result.stderr);
+    println!("stdout = {:?}", result.stdout);
+    assert!(result.success);
+    let result = scene.ucmd().arg("-a").run();
+    println!("stderr = {:?}", result.stderr);
+    println!("stdout = {:?}", result.stdout);
+    assert!(result.success);
+    assert!(result.stdout.contains(file));
+}