ls: force fetching metadata when called with -L -Z

The metadata are not used but it permits to check the symlink is valid.
We then return 1 on invalid symlinks when ls is invoked with ls -L -Z

Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>

src/uu/ls/src/ls.rs

@@ -3008,6 +3008,20 @@ fn display_inode(metadata: &Metadata) -> String {
 #[allow(unused_variables)]
 fn get_security_context(config: &Config, p_buf: &Path, must_dereference: bool) -> String {
     let substitute_string = "?".to_string();
+    // If we must dereference, ensure that the symlink is actually valid even if the system
+    // does not support SELinux.
+    // Conforms to the GNU coreutils where a dangling symlink results in exit code 1.
+    if must_dereference {
+        match get_metadata(p_buf, must_dereference) {
+            Err(err) => {
+                // The Path couldn't be dereferenced, so return early and set exit code 1
+                // to indicate a minor error
+                show!(LsError::IOErrorContext(err, p_buf.to_path_buf(), false));
+                return substitute_string;
+            }
+            Ok(md) => (),
+        }
+    }
     if config.selinux_supported {
         #[cfg(feature = "selinux")]
         {

tests/by-util/test_ls.rs

@@ -3137,6 +3137,16 @@ fn test_ls_dangling_symlinks() {
         .stderr_contains("No such file or directory")
         .stdout_contains(if cfg!(windows) { "dangle" } else { "? dangle" });
 
+    scene
+        .ucmd()
+        .arg("-LZ")
+        .arg("temp_dir")
+        .fails()
+        .code_is(1)
+        .stderr_contains("cannot access")
+        .stderr_contains("No such file or directory")
+        .stdout_contains(if cfg!(windows) { "dangle" } else { "? dangle" });
+
     scene
         .ucmd()
         .arg("-Ll")