chmod: modified no-op errors for parity with gnu

src/uu/chmod/locales/en-US.ftl

@@ -29,3 +29,4 @@ chmod-verbose-neither-changed = neither symbolic link {$file} nor referent has b
 chmod-verbose-mode-retained = mode of {$file} retained as {$mode_octal} ({$mode_display})
 chmod-verbose-failed-change = failed to change mode of file {$file} from {$old_mode} ({$old_mode_display}) to {$new_mode} ({$new_mode_display})
 chmod-verbose-mode-changed = mode of {$file} changed from {$old_mode} ({$old_mode_display}) to {$new_mode} ({$new_mode_display})
+chmod-permissions-changed = changing permissions of {$file}: {$errno}

src/uu/chmod/src/chmod.rs

@@ -13,7 +13,9 @@ use std::os::unix::fs::{MetadataExt, PermissionsExt};
 use std::path::{Path, PathBuf};
 use thiserror::Error;
 use uucore::display::Quotable;
-use uucore::error::{ExitCode, UError, UResult, USimpleError, UUsageError, set_exit_code};
+use uucore::error::{
+    ExitCode, UError, UResult, USimpleError, UUsageError, set_exit_code, strip_errno,
+};
 use uucore::fs::{FileInformation, display_permissions_unix};
 use uucore::mode;
 use uucore::perms::{TraverseSymlinks, configure_symlink_and_recursion};
@@ -772,13 +774,13 @@ impl Chmoder {
     }
 
     fn change_file(&self, fperm: u32, mode: u32, file: &Path) -> Result<(), i32> {
-        if fperm == mode {
-            // Use the helper method for consistent reporting
-            self.report_permission_change(file, fperm, mode);
-            Ok(())
-        } else if let Err(err) = fs::set_permissions(file, fs::Permissions::from_mode(mode)) {
+        // fs::set_permissions calls chmod which we need for the gnu test chmod/only-op.sh
+        if let Err(err) = fs::set_permissions(file, fs::Permissions::from_mode(mode)) {
             if !self.quiet {
-                show_error!("{err}");
+                show_error!(
+                    "{}",
+                    translate!("chmod-permissions-changed", "file" => file.quote(), "errno" => strip_errno(&err))
+                );
             }
             if self.verbose {
                 println!(

tests/by-util/test_chmod.rs

@@ -1500,3 +1500,14 @@ fn test_chmod_symlink_two_links_same_dir() {
         .stdout_contains("mode of 'base/link2/file'");
     // cSpell:enable
 }
+
+#[test]
+#[cfg(target_os = "linux")]
+fn test_chmod_permission_denied() {
+    let (_, mut ucmd) = at_and_ucmd!();
+
+    ucmd.args(&["+", "/"]).fails_with_code(1).stderr_is(
+        // spell-checker:disable-next-line
+        "chmod: changing permissions of '/': Operation not permitted\n",
+    );
+}